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Sample records for removal carbon sources

  1. Enhanced biological phosphorus removal with different carbon sources.

    PubMed

    Shen, Nan; Zhou, Yan

    2016-06-01

    Enhanced biological phosphorus removal (EBPR) process is one of the most economical and sustainable methods for phosphorus removal from wastewater. However, the performance of EBPR can be affected by available carbon sources types in the wastewater that may induce different functional microbial communities in the process. Glycogen accumulating organisms (GAOs) and polyphosphate accumulating organisms (PAOs) are commonly found by coexisting in the EBPR process. Predominance of GAO population may lead to EBPR failure due to the competition on carbon source with PAO without contributing phosphorus removal. Carbon sources indeed play an important role in alteration of PAOs and GAOs in EBPR processes. Various types of carbon sources have been investigated for EBPR performance. Certain carbon sources tend to enrich specific groups of GAOs and/or PAOs. This review summarizes the types of carbon sources applied in EBPR systems and highlights the roles of these carbon sources in PAO and GAO competition. Both single (e.g., acetate, propionate, glucose, ethanol, and amino acid) and complex carbon sources (e.g., yeast extract, peptone, and mixed carbon sources) are discussed in this review. Meanwhile, the environmental friendly and economical carbon sources that are derived from waste materials, such as crude glycerol and wasted sludge, are also discussed and compared. PMID:27087523

  2. Enhancement of post-anoxic denitrification for biological nutrient removal: effect of different carbon sources.

    PubMed

    Chen, Hong-bo; Wang, Dong-bo; Li, Xiao-ming; Yang, Qi; Zeng, Guang-ming

    2015-04-01

    Previous research has demonstrated that post-anoxic denitrification and biological nutrient removal could be achieved in the oxic/anoxic/extended-idle wastewater treatment regime. This study further investigated the effect of different carbon sources on post-anoxic denitrification and biological nutrient removal. Acetate, propionate (volatile fatty acids (VFAs)), glucose (carbohydrate), methanol, and ethanol (alcohol) were used as the sole carbon source, respectively. The experimental results showed that VFA substrates led to an improvement in nitrogen and phosphorus removal. The total nitrogen and phosphorus removal efficiency values driven by acetate achieved 93 and 99%, respectively. In contrast, glucose present in mixed liquor deteriorated total nitrogen and phosphorus removal efficiency values to 72 and 54%. In the reactors cultured with methanol and ethanol, 66 and 63% of the total nitrogen were removed, and phosphorus removal efficiency values were 78 and 71%, respectively. The mechanism studies revealed that different carbon sources affected the transformations of intracellular polyhydroxyalkanoates (PHAs) and glycogen. PHAs are the dominant storages for microorganisms cultured with VFA substrates. Though glycogen is not the favorable energy and carbon source for polyphosphate-accumulating organisms, it can be consumed by microorganisms related to biological nitrogen removal and is able to serve as the electron donor for post-anoxic denitrification. PMID:25354439

  3. [Nitrate removal from recirculating aquaculture system using polyhydroxybutyrate-co-hydroxyvalerate as carbon source ].

    PubMed

    Zhang, Lanhe; Liu, Lili; Qiu, Tianlei; Gao, Min; Han, Meilin; Yuan, Ding; Wang, Xuming

    2014-09-01

    [ OBJECTIVE] Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) was used as solid carbon source and biofilm carrier to remove nitrate from recirculating aquaculture system (RAS). Dynamics of microbial community structure in biofilm coating on carbon source packed into denitrification reactor were investigated. [METHODS] Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community in biofilm from denitrifiation reactor. Bacteria degrading PHBV were isolated from the reactor using pure culture method. [RESULTS] Nitrate decreased remarkably in the RAS connected with dentrification reactor. In contrast, Nitrate increased continuously in the conventional RAS without dentrification reactor. According to the phylogenetic analysis, the microbes in the biofilm samples from denitrification reactor were divided into Proteobacteria ( p-proteobacteria, γ-proteobacteria and δ- proteobacteria) , Firmicutes and Bacteroidetes. The major advantageous populations were Acidovorax and Bacillus in the 40-day reactor. The advantageous populations in the 150-day reactor were in order of Clostridium, Desulfitobacterium, Dechloromonas, Pseudoxanthomonas and Flavobacterium. Pure cultures of bacteria degrading PHBV isolated from denitrification reactor were classified into Acidovorax, Methylibium, Pseudoxanthomonas and Dechloromonas. [CONCLUSION] Nitrate could be removed effectively from RAS using PHBV as carbon source. Advantageous bacteria and their dynamic changes were ascertained in biofilm from denitrification reactor packed with PHBV. PMID:25522594

  4. Cassava stillage and its anaerobic fermentation liquid as external carbon sources in biological nutrient removal.

    PubMed

    Bu, Fan; Hu, Xiang; Xie, Li; Zhou, Qi

    2015-04-01

    The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal (BNR) from municipal wastewater in anaerobic-anoxic-aerobic sequencing batch reactors (SBRs). Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound (sodium acetate) served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-β-hydroxyalkanoates (PHAs), and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating organisms (PAOs) and denitrifying phosphorus accumulating organisms (DPAOs) demonstrated that the proportion of DPAOs to PAOs reached 62.6% (Day 86) and 61.8% (Day 65) when using cassava stillage and its anaerobic fermentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates (NURs) of the cassava by-products were in the range of 5.49-5.99 g N/(kg MLVSS⋅h) (MLVSS is mixed liquor volatile suspended solids) and 6.63-6.81 g N/(kg MLVSS⋅h), respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes. PMID:25845364

  5. Cassava stillage and its anaerobic fermentation liquid as external carbon sources in biological nutrient removal*

    PubMed Central

    Bu, Fan; Hu, Xiang; Xie, Li; Zhou, Qi

    2015-01-01

    The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal (BNR) from municipal wastewater in anaerobic-anoxic-aerobic sequencing batch reactors (SBRs). Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound (sodium acetate) served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-β-hydroxyalkanoates (PHAs), and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating organisms (PAOs) and denitrifying phosphorus accumulating organisms (DPAOs) demonstrated that the proportion of DPAOs to PAOs reached 62.6% (Day 86) and 61.8% (Day 65) when using cassava stillage and its anaerobic fermentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates (NURs) of the cassava by-products were in the range of 5.49–5.99 g N/(kg MLVSS∙h) (MLVSS is mixed liquor volatile suspended solids) and 6.63–6.81 g N/(kg MLVSS∙h), respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes. PMID:25845364

  6. High-rate nitrogen removal by the Anammox process with a sufficient inorganic carbon source.

    PubMed

    Yang, Jiachun; Zhang, Li; Fukuzaki, Yasuhiro; Hira, Daisuke; Furukawa, Kenji

    2010-12-01

    This study focused on high-rate nitrogen removal by the anaerobic ammonium oxidation (Anammox) process with a sufficient inorganic carbon (IC) source. Experiments were carried out in an up-flow column Anammox reactor fed with synthetic inorganic wastewater for 110 days. The IC source was added into the influent tank in the form of bicarbonate. The results confirmed the positive impact of inorganic matter on stimulating Anammox activity. After the addition of sufficient IC, the nitrogen removal rate sharply increased from 5.2 to 11.8 kg-Nm(-3)day(-1) within only 32 days. NO(2)-N inhibition was not observed even at NO(2)-N concentrations greater than 460 mgN/L, indicating the enriched Anammox consortium adapted to high NO(2)-N concentrations. The ratio of NO(2)-N removal, NO(3)-N production and NH(4)-N removal for the reactor was correspondingly changed from 1.21:0.21:1 to 1.24:0.18:1. Simultaneously, the sludge volume index of the Anammox granules decreased markedly from 36.8 to 21.5 mL/g, which was attributed to the implementation of proper operational strategy. In addition, DNA analysis revealed that a shift from the KSU-1 strain to the KU2 strain occurred in the Anammox community. PMID:20709538

  7. [Advanced nitrogen removal using innovative denitrification biofilter with sustained-release carbon source material].

    PubMed

    Tang, Lei; Li, Peng; Zuo, Jian-e; Yuan, Lin; Li, Zai-xing

    2013-09-01

    An innovative denitrification biofilter was developed with polycaprolactone (PCL) as the carbon source and biofilm carrier. The performance of nitrogen removal was investigated with biologically treated effluent from secondary clarifier, and the results indicated that a maximum TN removal efficiency of 98.9% was achieved under the following conditions: influent total nitrogen (TN) concentration 30.0 mg x L(-1), denitrification load 54.0 mg (L x h)(-1), operating temperature 20. 1-22.0 degrees C, hydraulic retention time 0. 5 h; the total organic carbon (TOC) in effluent was 6.5-8.4 mg x L(-1), which was increased by 2.0-3.0 mg x L(-1) compared with that in the influent; the suspended solids (SS) concentration was less than 4.0 mg x L(-1) during operation; nearly 84.2% of the total released organic carbon which was used as electron donor in the denitrification process, was derived in the presence of microbes. The surface of the PCL pellets was observed by scanning electron microscope (SEM), it was shown that thick biofilm was formed on the surface of pellets, and the main microbial species were Bacillus and Trichobacteria. PMID:24289000

  8. Effects of macrophytes and external carbon sources on nitrate removal from groundwater in constructed wetlands.

    PubMed

    Lin, Ying-Feng; Jing, Shuh-Ren; Wang, Tze-Wen; Lee, Der-Yuan

    2002-01-01

    Several microcosm wetlands unplanted and planted with five macrophytes (Phragmites australis, Commelina communis, Penniserum purpureum, Ipomoea aquatica, and Pistia stratiotes) were employed to remove nitrate from groundwater at a concentration of 21-47 mg NO3-N/l. In the absence of external carbon, nitrate removal rates ranged from 0.63 to 1.26 g NO3-N/m2/day for planted wetlands. Planted wetlands exhibited significantly greater nitrate removal than unplanted wetlands (P<0.01), indicating that macrophytes are essential to efficient nitrate removal. Additionally, a wetland planted with Penniserum showed consistently higher nitrate removal than those planted with the other four macrophytes, suggesting that macrophytes present species-specific nitrate removal efficiency possibly depending on their ability to produce carbon for denitrification. Although adding external carbon to the influent improved nitrate removal, a significant fraction of the added carbon was lost via microbial oxidation in the wetlands. Planting a wetland with macrophytes with high productivity may be an economic way for removing nitrate from groundwater. According to the harvest result, 4-11% of nitrogen removed by the planted wetland was due to vegetation uptake, and 89-96% was due to denitrification. PMID:12166674

  9. Innovative use of activated carbon for the removal of heavy metals from ground water sources

    SciTech Connect

    Lewis, T. III

    1996-12-31

    This report discusses the evaluation of the ENVIRO-CLEAN PROCESS, a technology developed by Lewis Environmental Services, Inc. for the recovery of metals such as chromium, mercury, copper, cadmium, lead, and zinc from surface and groundwater streams. This new heavy metal removal process (patent-pending) utilizes granular activated carbon with a proprietary conditioning pretreatment to enhance heavy metal adsorption combined with electrolytic metal recovery to produce a saleable metallic product. The process generates no sludge or hazardous waste and the effluent meets EPA limits. A 50 gpm system was installed for recovering hexavalent chromium from a ground water stream at a site located in Fresno, California. The effluent from the activated carbon system was reinjected into the ground water table with the hexavalent chromium concentration < 10 ppb. The system simultaneously removed trichloroethylene (TCE) to concentrations levels < 05 ppb. The activated carbon is regenerated off-site and the chromium electrolytically recovered. The full scale system has treated over 5 million gallons of ground water since installation. 5 refs., 1 fig., 3 tabs.

  10. [Optimization Study on the Nitrogen and Phosphorus Removal of Modified Two- sludge System Under the Condition of Low Carbon Source].

    PubMed

    Yang, Wei-qiang; Wang, Dong-bo; Li, Xiao-ming; Yang, Qi; Xu, Qiu-xiang; Zhang, Zhi-bei; Li, Zhi-jun; Xiang, Hai-hong; Wang, Ya-li; Sun, Jian

    2016-04-15

    This paper explored the method of resolving insufficient carbon source in urban sewage by comparing and analyzing denitrification and phosphorus removal (NPR) effect between modified two-sludge system and traditional anaerobic-aerobic-anoxic process under the condition of low carbon source wastewater. The modified two-sludge system was the experimental reactor, which was optimized by adding two stages of micro-aeration (aeration rate 0.5 L · mm⁻¹) in the anoxic period of the original two-sludge system, and multi-stage anaerobic-aerobic-anoxic SBR was the control reactor. When the influent COD, ammonia nitrogen, SOP concentration were respectively 200, 35, 10 mg · L⁻¹, the NPR effect of the experimental reactor was hetter than that of thecontrol reactor with the removal efficiency of TN being 94.8% vs 60.9%, and TP removal being 96.5% vs 75%, respectively. The effluent SOP, ammonia, TN concentration of the experimental reactor were 0.35, 0.50, 1.82 mg · L⁻¹, respectively, which could fully meet the first class of A standard of the Pollutants Emission Standard of Urban Wastewater Treatment Firm (GB 18918-2002). Using the optimized treatment process, the largest amounts of nitrogen and phosphorus removal per unit carbon source (as COD) were 0.17 g · g⁻¹ and 0.048 g · g⁻¹ respectively, which could furthest solve the lower carbon concentration in current municipal wastewater. PMID:27548974

  11. [Effects of carbon sources, temperature and electron acceptors on biological phosphorus removal].

    PubMed

    Han, Yun; Xu, Song; Dong, Tao; Wang, Bin-Fan; Wang, Xian-Yao; Peng, Dang-Cong

    2015-02-01

    Effects of carbon sources, temperature and electron acceptors on phosphorus uptake and release were investigated in a pilot-scale oxidation ditch. Phosphorus uptake and release rates were measured with different carbon sources (domestic sewage, sodium acetate, glucose) at 25 degrees C. The results showed that the minimum phosphorus uptake and release rates of glucose were 5.12 mg x (g x h)(-1) and 6.43 mg x (g x h)(-1), respectively, and those of domestic sewage are similar to those of sodium acetate. Phosphorus uptake and release rates increased with the increase of temperature (12, 16, 20 and 25 degrees C) using sodium acetate as carbon sources. Anoxic phosphorus uptake rate decreased with added COD. Electron acceptors (oxygen, nitrate, nitrite) had significant effects on phosphorus uptake rate and their order was in accordance with oxygen > nitrate > nitrite. The mass ratio of anoxic P uptake and N consumption (P(uptake)/N (consumption)) of nitrate and nitrite were 0.96 and 0.65, respectively. PMID:26031087

  12. Biological nitrate removal using a food waste-derived carbon source in synthetic wastewater and real sewage.

    PubMed

    Zhang, Haowei; Jiang, Jianguo; Li, Menglu; Yan, Feng; Gong, Changxiu; Wang, Quan

    2016-01-15

    The production of volatile fatty acids (VFAs) from food waste to improve biological nutrient removal has drawn much attention. In this study, acidogenic liquid from food waste was used as an alternative carbon source for synthetic wastewater treatment. C/N ratios of 5 and 6 were suitable for denitrification, and the change in acidogenic liquid composition had no negative effect on denitrification. The denitrification rates using optimal carbon-to-nitrate ratios of acidogenic liquid were more than 25 mg NO3-N/(gVSS·h). At the same time, acidogenic liquid was used to improve nutrient removal from summer and winter sewage. C/N ratios of 5 and 6 were acceptable for summer sewage treatment. Total nitrogen in the final effluent was less than 7 mg/L. Two additional hours were required for winter sewage treatment, and the C/N ratio had to be >6. PMID:26547269

  13. Influence of carbon source on nutrient removal performance and physical-chemical characteristics of aerobic granular sludge.

    PubMed

    Lashkarizadeh, Monireh; Yuan, Qiuyan; Oleszkiewicz, Jan A

    2015-01-01

    The impact of carbon source variation on the physical and chemical characteristics of aerobic granular sludge and its biological nutrient (nitrogen and phosphorus) removal performance was investigated. Two identical sequencing batch reactors, R1 and R2, were set up. Granular biomass was cultivated to maturity using acetate-based synthetic wastewater. After mature granules in both reactors with simultaneous chemical oxygen demand (COD), ammonium and phosphorus removal capability were achieved, the feed of R2 was changed to municipal wastewater and R1 was continued on synthetic feed as control. Biological phosphorus removal was completely inhibited in R2 due to lack of readily biodegradable COD; however, the biomass maintained high ammonium and COD removal efficiencies. The disintegration of the granules in R2 occurred during the first two weeks after the change of feed, but it did not have significant impacts on settling properties of the sludge. Re-granulation of the biomass in R2 was then observed within 30 d after granules' disintegration when the biomass acclimated to the new substrate. The granular biomass in R1 and R2 maintained a Sludge Volume Index close to 60 and 47 mL g(-1), respectively, during the experimental period. It was concluded that changing the carbon source from readily biodegradable acetate to the more complex ones present in municipal wastewater did not have significant impacts on aerobic granular sludge characteristics; it particularly did not affect its settling properties. However, sufficient readily biodegradable carbon would have to be provided to maintain simultaneous biological nitrate and phosphorus removal. PMID:25719420

  14. [Shortcut Nitrosation-Denitrifying Phosphorus Removal Based on High-quality Carbon Source in Combined Process of CAMBR].

    PubMed

    Cheng, Ji-hui; Wu, Peng; Cheng, Chao-yang; Shen, Yao-liang

    2015-12-01

    The volatile fatty acids (VFAs) are high-quality carbon source which can be utilized in the process of denitrifying phosphorus removal. Therefore, a combined process of anaerobic baffled reactor (ABR) with microbial phase separation and membrane bioreactor (MBR), i. e. CAMBR, with high-quality effluent was investigated in this experiment for highly efficient denitrifying phosphorus removal through providing high-quality carbon source by optimizing operational conditions such as hydraulic retention time (HRT) in the ABR. The results indicated that sufficient high-quality carbon source VFA could be acquired when the HRT of ABR was 4.8 h. The consumption of VFA was 56. 1 mg · L⁻¹ while the release of phosphorus was 10.43 mg · L⁻¹ showing that 5.38 mg of VFA was required to release 1 mg PO₄³⁻-P. Meanwhile, the uptake of phosphorus was 12. 35 mg · L⁻¹, while the uptake of phosphorus of MBR tank was 1.33 mg · L⁻¹. In the process of shortcut nitrification, 0.62 mg NOx⁻-N was needed when 1 mg PO₄³⁻-P was taken up, and 1.67 to 2.04 mg NO₂⁻-N was required when 1 mg PO₄³⁻-P was taken up, and the combined system achieved stable effluent quality. The average removal rates of COD, TN and soluble PO₄³⁻-P were 91%, 84% and 93%, respectively, correspondingly the average effluent concentrations were 30, 7.15 and 0.55 mg · L⁻¹, respectively. The results stated that the CAMBR achieved stable and highly efficient denitrifying phosphorus removal in domestic sewage treatment. PMID:27011991

  15. Modeling the Effect of External Carbon Source Addition under Different Electron Acceptor Conditions in Biological Nutrient Removal Activated Sludge Systems.

    PubMed

    Hu, Xiang; Wisniewski, Kamil; Czerwionka, Krzysztof; Zhou, Qi; Xie, Li; Makinia, Jacek

    2016-02-16

    The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to predict the aerobic/anoxic behavior of polyphosphate accumulating organisms (PAOs) and "ordinary" heterotrophs in the presence of different external carbon sources and electron acceptors. The following new aspects were considered: (1) a new type of the readily biodegradable substrate, not available for the anaerobic activity of PAOs, (2) nitrite as an electron acceptor, and (3) acclimation of "ordinary" heterotrophs to the new external substrate via enzyme synthesis. The expanded model incorporated 30 new or modified process rate equations. The model was evaluated against data from several, especially designed laboratory experiments which focused on the combined effects of different types of external carbon sources (acetate, ethanol and fusel oil) and electron acceptors (dissolved oxygen, nitrate and nitrite) on the behavior of PAOs and "ordinary" heterotrophs. With the proposed expansions, it was possible to improve some deficiencies of the ASM2d in predicting the behavior of biological nutrient removal (BNR) systems with the addition of external carbon sources, including the effect of acclimation to the new carbon source. PMID:26783836

  16. Molasses as an efficient low-cost carbon source for biological Cr(VI) removal.

    PubMed

    Michailides, Michail K; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Coles, Sandra; Pavlou, Stavros; Vayenas, Dimitrios V

    2015-01-01

    In the present study, indigenous microorganisms from industrial sludge were used to reduce the activity of Cr(VI). Molasses, a by-product of sugar processing, was selected as the carbon source (instead of sugar used in a previous work) as it is a low-cost energy source for bioprocesses. Initially, experiments were carried out in suspended growth batch reactors for Cr(VI) concentrations of 1.5-110 mg/L. The time required for complete Cr(VI) reduction increased with initial Cr(VI) concentration. Initial molasses concentration was also found to influence the Cr(VI) reduction rate. The optimal concentration for all initial Cr(VI) concentrations tested was 0.8 gC/L. Experiments were also carried out in packed-bed reactors. Three different operating modes were used to investigate the optimal performance and efficiency of the filter, i.e. batch, continuous and SBR with recirculation. The latter mode with a recirculation rate of 0.5L/min lead to significantly high Cr(VI) reduction rates (up to 135 g/m(2)d). The results of this work were compared with those of a similar work using sugar as the carbon source and indicate that molasses could prove a feasible technological solution to a serious environmental problem. PMID:25160055

  17. Simultaneous ammonia and nitrate removal in an airlift reactor using poly(butylene succinate) as carbon source and biofilm carrier.

    PubMed

    Ruan, Yun-Jie; Deng, Ya-Le; Guo, Xi-Shan; Timmons, Michael B; Lu, Hui-Feng; Han, Zhi-Ying; Ye, Zhang-Ying; Shi, Ming-Ming; Zhu, Song-Ming

    2016-09-01

    In this study, an airlift inner-loop sequencing batch reactor using poly(butylene succinate) as the biofilm carrier and carbon source was operated under an alternant aerobic/anoxic strategy for nitrogen removal in recirculating aquaculture system. The average TAN and nitrate removal rates of 47.35±15.62gNH4-Nm(-3)d(-1) and 0.64±0.14kgNO3-Nm(-3)d(-1) were achieved with no obvious nitrite accumulation (0.70±0.76mg/L) and the dissolved organic carbon in effluents was maintained at 148.38±39.06mg/L. Besides, the activities of dissimilatory nitrate reduction to ammonium and sulfate reduction activities were successfully inhibited. The proteome KEGG analysis illustrated that ammonia might be removed through heterotrophic nitrification, while the activities of nitrate and nitrite reductases were enhanced through aeration treatment. The microbial community analysis revealed that denitrifiers of Azoarcus and Simplicispira occupied the dominate abundance which accounted for the high nitrate removal performance. Overall, this study broadened our understanding of simultaneous nitrification and denitrification using biodegradable material as biofilm carrier. PMID:27343453

  18. Industrial wastewater as an external carbon source for optimization of nitrogen removal at the Wschod WWTP in Gdansk (Poland).

    PubMed

    Swinarski, M; Makinia, J; Czerwionka, K; Chrzanowska, M

    2009-01-01

    Carbon source alternatives for denitrification belong to the highest research area priorities as they allow to optimize N removal within the existing capacities. In particular, some food industry effluents appear to be good candidates for such alternatives due to their high C/N ratios and high content of readily biodegradable organic fraction. The aim of this study was to determine the immediate effects of dosing different types of industrial wastewater on the denitrification capability of process biomass originating from the "Wschod" WWTP in Gdansk (northern Poland). Three types of industrial wastewater (effluents from a distillery, brewery and fish-pickling factory) were tested in two kinds of batch experiments. The results of this study revealed that the investigated industrial wastewater can be a potential external carbon source to improve denitrification efficiency. The observed single nitrate utilization rates (NURs) were ranging from 2.4 to 6.0 g N/(kg VSS.h) and were comparable to the rates associated with the utilization of readily biodegradable COD in the settled wastewater. When the NURs were measured during anoxic P uptake, the P uptake rates did not appear to be adversely affected by the addition of any carbon source. PMID:19151486

  19. Use of external carbon sources derived from biowaste for short-cut nutrient removal from anaerobic effluents.

    PubMed

    Katsou, Evina; Frison, Nicola; Malamis, Simos; Fatone, Francesco

    2014-01-01

    This work evaluated the use of different external carbon sources to promote the via-nitrite nutrient removal from anaerobic effluents. The carbon sources consisted of fermentation liquid produced from the organic fraction of municipal solid waste (OFMSW FL), drainage liquid produced from OFMSW, fermentation liquid produced from vegetable and fruit waste (VFW FL) and acetic acid. Denitritation and phosphorus uptake via nitrite were evaluated in two sequencing batch reactors, one treating the anaerobic supernatant produced from the co-digestion of OFMSW and activated sludge (highly nitrogenous anaerobic effluent - HNAE), and the other one treating the weakly nitrogenous anaerobic effluent (WNAE) from an upflow anaerobic sludge blanket reactor. The use of OFMSW FL to treat HNAE resulted in high nitrite (27 mgN/(gVSS·h) (VSS - volatile suspended solids) and phosphate uptake (15 mgP/gVSS·h). In the WNAE, nutrient kinetics were much slower. The use of acetic acid and VFW FL performed poorly, while the use of OFMSW FL, which was rich in butyric acid and propionic acid, resulted in significant nutrient removal (7 mgN/gVSS·h and 6 mgP/gVSS·h). The economic evaluation showed that the use of OFMSW FL is a less expensive option than the acetic acid use. PMID:24804659

  20. Influence of carbon source on nitrate removal by nitrate-tolerant Klebsiella oxytoca CECT 4460 in batch and chemostat cultures

    SciTech Connect

    Pinar, G.; Ramos, J.L.; Kovarova, K.; Egli, T.

    1998-08-01

    The nitrate-tolerant organism Klebsiella oxytoca CECT-4460 tolerates nitrate at concentrations up to 1 M and is used to treat wastewater with high nitrate loads in industrial wastewater treatment plants. The authors studied the influence of the C source (glycerol or sucrose or both) on the growth rate and the efficiency of nitrate removal under laboratory conditions. With sucrose as the sole C source the maximum specific growth rate was 0.3 h{sup {minus}1}, whereas with glycerol it was 0.45 h{sup {minus}1}. In batch cultures K. oxytoca cells grown on sucrose or glycerol were able to immediately use sucrose as a sole C source, suggesting that sucrose uptake and metabolism were constitutive. In contrast, glycerol uptake occurred preferentially in glycerol-grown cells. Independent of the preculture conditions, when sucrose and glycerol were added simultaneously to batch cultures, the sucrose was used first, and once the supply of sucrose was exhausted, the glycerol was consumed. Utilization of nitrate as an N source occurred without nitrite of ammonium accumulation when glycerol was used, but nitrite accumulated when sucrose was used. In chemostat cultures K. oxytoca CECT 4460 efficiently removed nitrate without accumulation of nitrite or ammonium when sucrose, glycerol, or mixtures of these two C sources were used. The growth yields and the efficiencies of C and N utilization were determined at different growth rates in chemostat cultures. Regardless of the C source, yield carbon (Y{sub C}) ranged between 1.3 and 1.0 g (dry weight) per g of sucrose C or glycerol C consumed. Regardless of the specific growth rate and the C source, yield nitrogen (Y{sub N}) ranged from 17.2 to 12.5 g (dry weight) per g of nitrate N consumed.

  1. Improved biological phosphorus removal performance driven by the aerobic/extended-idle regime with propionate as the sole carbon source.

    PubMed

    Wang, Dongbo; Li, Xiaoming; Yang, Qi; Zheng, Wei; Wu, Yan; Zeng, Tianjing; Zeng, Guangming

    2012-08-01

    Our previous studies proved that biological phosphorus removal (BPR) could be achieved in an aerobic/extended-idle (AEI) process employing two typical substrates of glucose and acetate as the carbon sources. This paper further evaluated the feasibility of another important substrate, propionate, serving as the carbon source for BPR in the AEI process, and compared the BPR performance between the AEI and anaerobic/oxic (A/O) processes. Two sequencing batch reactors (SBRs) were operated, respectively, as the AEI and A/O regimes for BPR using propionate as the sole substrate. The results showed that the AEI-reactor removed 2.98 ± 0.04-4.06 ± 0.06 mg of phosphorus per g of total suspended solids during the course of the steady operational trial, and the phosphorus content of the dried sludge was reached 8.0 ± 0.4% after 56-day operation, demonstrating the good performance of phosphorus removal. Then, the efficiencies of BPR and the transformations of the intracellular storages were compared between two SBRs. It was observed that the phosphorus removal efficiency was maintained around 95% in the AEI-reactor, and about 83% in the A/O-reactor, although the latter showed much greater transformations of both polyhydroxyalkanoates and glycogen. The facts clearly showed that BPR could be enhanced by the AEI regime using propionate as the carbon source. Finally, the mechanisms for the propionate fed AEI-reactor improving BPR were investigated. It was found that the sludge cultured by the AEI regime had more polyphosphate containing cells than that by the A/O regime. Further investigation revealed that the residual nitrate generated in the last aerobic period was readily deteriorated BPR in the A/O-SBR, but a slight deterioration was observed in the AEI-SBR. Moreover, the lower glycogen transformation measured in the AEI-SBR indicated that the biomass cultured by the AEI regime contained less glycogen accumulating organisms activities than that by the A/O regime. PMID

  2. ENHANCED SOURCE REMOVAL

    EPA Science Inventory

    Two physically and hydraulically isolated test cells have been constructed at the Groundwater Remediation Field Laboratory at Dover Air Force Base, Delaware. The effectiveness of five in-situ techniques for removing DNAPL from soils and aquifers will be evaluated in these cells u...

  3. Influence of COD/N ratio and carbon source on nitrogen removal in a structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA).

    PubMed

    Santos, Carla E D; Moura, Rafael B; Damianovic, Márcia H R Z; Foresti, Eugenio

    2016-01-15

    This study aimed to evaluate the influence of COD/N ratio and carbon source on simultaneous nitrogen and carbon removal processes. A continuous up-flow structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) was operated with hydraulic retention time (HRT) of 11.2 ± 0.6 h. The carbon sources were meat peptone and sucrose. The COD/N ratio varied by maintaining the organic loading rate fixed at 1.07 kg COD m(-3) d(-1) and changing the total-N concentration. The COD/N ratios tested were 9.7 ± 1 (sucrose); 7.6 ± 1 (meat peptone); 2.9 ± 1 (meat peptone) and 2.9 ± 0.4 (sucrose). COD removal efficiencies remained above 90% in all experimental phases. At lower COD/N ratios, NH4(+)-N oxidation efficiencies were higher than 90%. An autotrophic metabolism by anammox process was observed in Phases III and IV, which was responsible for 35% and 27% of total-N loading removal rates, respectively. Therefore, the system achieved total nitrogen removal efficiencies of 84.6 ± 10.1 and 81.5 ± 5.3%, under low availability of organic electron donors. PMID:26595179

  4. Effect of carbon source on biomass growth and nutrients removal of Scenedesmus obliquus for wastewater advanced treatment and lipid production.

    PubMed

    Shen, Qiao-Hui; Jiang, Jia-Wei; Chen, Li-Ping; Cheng, Li-Hua; Xu, Xin-Hua; Chen, Huan-Lin

    2015-08-01

    The combination of tertiary wastewater treatment and microalgal lipid production is considered to be a promising approach to water eutrophication as well as energy crisis. To intensify wastewater treatment and microalgal biofuel production, the effect of organic and inorganic carbon on algal growth and nutrient removal of Scenedesmus obliquus were examined by varying TOC (total organic carbon) concentrations of 20-120mgL(-1) in wastewater and feeding CO2 concentrations in the range of 0.03-15%, respectively. The results showed that the maximal biomass and average lipid productivity were 577.6 and 16.7mgL(-1)d(-1) with 5% CO2 aeration. The total nitrogen, total phosphorus and TOC removal efficiencies were 97.8%, 95.6% and 59.1% respectively within 6days when cultured with real secondary municipal wastewater. This work further showed that S. obliquus could be utilized for simultaneous organic pollutants reduction, N, P removal and lipid accumulation. PMID:25958150

  5. Carbon dioxide removal process

    DOEpatents

    Baker, Richard W.; Da Costa, Andre R.; Lokhandwala, Kaaeid A.

    2003-11-18

    A process and apparatus for separating carbon dioxide from gas, especially natural gas, that also contains C.sub.3+ hydrocarbons. The invention uses two or three membrane separation steps, optionally in conjunction with cooling/condensation under pressure, to yield a lighter, sweeter product natural gas stream, and/or a carbon dioxide stream of reinjection quality and/or a natural gas liquids (NGL) stream.

  6. Long-term natural attenuation of carbon and nitrogen within a groundwater plume after removal of the treated wastewater source

    USGS Publications Warehouse

    Repert, D.A.; Barber, L.B.; Hess, K.M.; Keefe, S.H.; Kent, D.B.; LeBlanc, D.R.; Smith, R.L.

    2006-01-01

    Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1-4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen in groundwater were relatively constant with time and distance, but substantially elevated above background. The contaminant plume core remained anoxic for the entire 10-year study period; temporal patterns of integrated oxygen deficit decreased slowly at all sites. In 2004, substantial amounts of total dissolved carbon (7 mol C m-2) and fixed (dissolved plus sorbed) inorganic nitrogen (0.5 mol N m-2) were still present in a 28-m vertical interval at the disposal site. Sorbed constituents have contributed substantially to the dissolved carbon and nitrogen pools and are responsible for the long-term persistence of the contaminant plume. Natural aquifer restoration at the discharge location will take at least several decades, even though groundwater flow rates and the potential for contaminant flushing are relatively high.

  7. Tertiary nitrogen removal for municipal wastewater using a solid-phase denitrifying biofilter with polycaprolactone as the carbon source and filtration medium.

    PubMed

    Li, Peng; Zuo, Jiane; Wang, Yajiao; Zhao, Jian; Tang, Lei; Li, Zaixing

    2016-04-15

    Tertiary nitrogen removal technologies are needed to reduce the excess nitrogen that is discharged into sensitive aquatic ecosystems. An integrated solid-phase denitrification biofilter (SDNF) was developed with dual media to remove nitrate and suspended solids (SS) from the secondary effluent of municipal wastewater treatment plants. Biodegradable polymer pellets of polycaprolactone (PCL) served as the biofiltration medium and carbon source for denitrification. Long-term continuous operation of the SDNF was conducted with real secondary effluent to evaluate the denitrification performance and effects of influent nitrate loading rates (NLR) and operating temperatures. The results indicated that both nitrate and SS were effectively removed. The SDNF had a strong tolerance for fluctuations in influent NLR, and a maximum denitrification rate of 3.80 g N/(L·d) was achieved. The low temperature had a significant impact on nitrogen removal, yet the denitrification rate was still maintained at a relative high level to as much as 1.23 g N/(L·d) even at approximately 8.0 °C in winter. Nitrite accumulation and excessive organics residue in the effluent were avoided throughout the whole experiment, except on occasional days in the lag phase. The observed biomass yield was calculated to be 0.44 kgVSS/kgPCL. The microbial diversity and community structure of the biofilm in the SDNF were revealed by Illumina high-throughput sequencing. The special carbon source led to an obvious succession of microbial community from the initial inoculum (activated sludge from aerobic tanks), and included a decrease in microbial diversity and a shift in the dominant groups, which were identified to be members of the family Comamonadaceae in the SDNF. The SDNF developed in this study was verified to be an efficient technology for tertiary nitrogen removal from secondary effluent. PMID:26897042

  8. Investigation of the Makeup, Source, and Removal Strategies for Total Organic Carbon in the Oxygen Generation System Recirculation Loop

    NASA Technical Reports Server (NTRS)

    Bowman, Elizabeth M.; Carpenter, Joyce; Roy, Robert J.; Van Keuren, Steve; Wilson, Mark E.

    2015-01-01

    Since 2007, the Oxygen Generation System (OGS) on board the International Space Station (ISS) has been producing oxygen for crew respiration via water electrolysis. As water is consumed in the OGS recirculating water loop, make-up water is furnished by the ISS potable water bus. A rise in Total Organic Carbon (TOC) was observed beginning in February, 2011, which continues through the present date. Increasing TOC is of concern because the organic constituents responsible for the TOC were unknown and had not been identified; hence their impacts on the operation of the electrolytic cell stack components and on microorganism growth rates and types are unknown. Identification of the compounds responsible for the TOC increase, their sources, and estimates of their loadings in the OGA as well as possible mitigation strategies are presented.

  9. Effect of dissolved oxygen on nitrate removal using polycaprolactone as an organic carbon source and biofilm carrier in fixed-film denitrifying reactors.

    PubMed

    Luo, Guozhi; Xu, Guimei; Gao, Jinfang; Tan, Hongxin

    2016-05-01

    Nitrate-nitrogen (NO3(-)-N) always accumulates in commercial recirculating aquaculture systems (RASs) with aerobic nitrification units. The ability to reduce NO3(-)-N consistently and confidently could help RASs to become more sustainable. The rich dissolved oxygen (DO) content and sensitive organisms stocked in RASs increase the difficulty of denitrifying technology. A denitrifying process using biologically degradable polymers as an organic carbon source and biofilm carrier was proposed because of its space-efficient nature and strong ability to remove NO3(-)-N from RASs. The effect of dissolved oxygen (DO) levels on heterotrophic denitrification in fixed-film reactors filled with polycaprolactone (PCL) was explored in the current experiment. DO conditions in the influent of the denitrifying reactors were set up as follows: the anoxic treatment group (Group A, average DO concentration of 0.28±0.05mg/L), the low-oxygen treatment DO group (Group B, average DO concentration of 2.50±0.24mg/L) and the aerated treatment group (Group C, average DO concentration of 5.63±0.57mg/L). Feeding with 200mg/L of NO3(-)-N, the NO3(-)-N removal rates were 1.53, 1.60 and 1.42kg/m(3) PCL/day in Groups A, B and C, respectively. No significant difference in NO3(-)-N removal rates was observed among the three treatments. It was concluded that the inhibitory effects of DO concentrations lower than 6mg/L on heterotrophic denitrification in the fixed-film reactors filled with PCL can be mitigated. PMID:27155419

  10. Investigation into cyclic utilization of carbon source in an advanced sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal (SIPER) wastewater treatment process.

    PubMed

    Yan, Peng; Ji, Fang-Ying; Wang, Jing; Chen, You-Peng; Shen, Yu; Fang, Fang; Guo, Jin-Song

    2015-01-01

    An advanced wastewater treatment process (SIPER) was developed to simultaneously reduce sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The ability to recover organic substance from excess sludge to enhance nutrient removal (especially nitrogen) and its performance as a C-source were evaluated in this study. The chemical oxygen demand/total nitrogen (COD/TN) and volatile fatty acids/total phosphorus (VFA/TP) ratios for the supernatant of the alkaline-treated sludge were 3.1 times and 2.7 times those of the influent, respectively. The biodegradability of the supernatant was much better than that of the influent. The system COD was increased by 91 mg/L, and nitrogen removal was improved by 19.6% (the removal rate for TN reached 80.4%) after the return of the alkaline-treated sludge as an internal C-source. The C-source recovered from the excess sludge was successfully used to enhance nitrogen removal. The internal C-source contributed 24.1% of the total C-source, and the cyclic utilization of the system C-source was achieved by recirculation of alkaline-treated sludge in the sludge reduction, inorganic solids separation, phosphorus recovery (SIPER) process. PMID:26524455

  11. Simultaneous removal of chromate and nitrate in a packed-bed bioreactor using biodegradable meal box as carbon source and biofilm carriers.

    PubMed

    Li, Jie; Jin, Ruofei; Liu, Guangfei; Tian, Tian; Wang, Jing; Zhou, Jiti

    2016-05-01

    An up-flow packed-bed bioreactor was constructed to investigate the simultaneous removal of chromate and nitrate using biodegradable meal box as carbon source and biofilm carriers. The bioreactor was operated for 164days with varying influent Cr(VI) concentrations (2.0-50.0mg/L) and hydraulic retention times (HRT, 10-24h). It was shown that complete denitrification and Cr(VI) reduction could be achieved when influent Cr(VI) concentrations were lower than 20mg/L with a HRT of 17h. Shortening the HRT could significantly reduce the effluent CODcr. It was also observed that Cr(III) was mainly immobilized on the biofilm. Further investigation on Cr distribution in the biofilm compartments indicated that Cr(VI) reduction occurred in all compartments and the intercellular Cr was dominant. High-throughput sequencing analysis showed that Proteobacteria, Bacteroidetes and Firmicutes were the dominant phyla in the biofilm and Cr(VI) stress had a negative effect on the abundance of most bacteria. PMID:26896715

  12. Process for removing carbon from uranium

    DOEpatents

    Powell, George L.; Holcombe, Jr., Cressie E.

    1976-01-01

    Carbon contamination is removed from uranium and uranium alloys by heating in inert atmosphere to 700.degree.-1900.degree.C in effective contact with yttrium to cause carbon in the uranium to react with the yttrium. The yttrium is either in direct contact with the contaminated uranium or in indirect contact by means of an intermediate transport medium.

  13. Process for removing carbonate from wells

    SciTech Connect

    Derowisch, R.W.

    1989-11-14

    This patent describes a method of removing carbonate deposited in a water supply well by inflowing groundwater. It comprises: treating a supply of water by means of a membrane system for desalinization which places the water in an aggressive state of chemical inequilibrium and ion imbalance having a keen affinity for carbonate; pumping a fluid comprising the treated supply of water, without restabilization, into the well to react with the deposited carbonate; and flushing the product of the reaction from the well.

  14. Carbon Dioxide Removal via Passive Thermal Approaches

    NASA Technical Reports Server (NTRS)

    Lawson, Michael; Hanford, Anthony; Conger, Bruce; Anderson, Molly

    2011-01-01

    A paper describes a regenerable approach to separate carbon dioxide from other cabin gases by means of cooling until the carbon dioxide forms carbon dioxide ice on the walls of the physical device. Currently, NASA space vehicles remove carbon dioxide by reaction with lithium hydroxide (LiOH) or by adsorption to an amine, a zeolite, or other sorbent. Use of lithium hydroxide, though reliable and well-understood, requires significant mass for all but the shortest missions in the form of lithium hydroxide pellets, because the reaction of carbon dioxide with lithium hydroxide is essentially irreversible. This approach is regenerable, uses less power than other historical approaches, and it is almost entirely passive, so it is more economical to operate and potentially maintenance- free for long-duration missions. In carbon dioxide removal mode, this approach passes a bone-dry stream of crew cabin atmospheric gas through a metal channel in thermal contact with a radiator. The radiator is pointed to reject thermal loads only to space. Within the channel, the working stream is cooled to the sublimation temperature of carbon dioxide at the prevailing cabin pressure, leading to formation of carbon dioxide ice on the channel walls. After a prescribed time or accumulation of carbon dioxide ice, for regeneration of the device, the channel is closed off from the crew cabin and the carbon dioxide ice is sublimed and either vented to the environment or accumulated for recovery of oxygen in a fully regenerative life support system.

  15. Carbon dioxide removal with inorganic membranes

    SciTech Connect

    Judkins, R.R.; Fain, D.E.

    1993-12-31

    The increasing concentrations of greenhouse gases, particularly carbon dioxide, in the atmosphere has sparked a great deal of interest in the removal of CO{sub 2} from flue gases of fossil fueled plants. Presently, several techniques for the removal of CO{sub 2} are considered to have potential, but are lacking in practicality. For example, amine scrubbing of flue gas streams is potential, but are lacking in practically. For example, amine scrubbing of flue gas streams is effective in removing CO{sub 2}, but costs are high; efficiency suffers; and other acid gases must be removed prior to amine stripping. Membrane systems for CO{sub 2} removal are held in high regard, and inorganic, particularly ceramic, membranes offer the potential for high temperature, thus energy saving, removal.

  16. Tritium Removal from Carbon Plasma Facing Components

    SciTech Connect

    C.H. Skinner; J.P. Coad; G. Federici

    2003-11-24

    Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating.

  17. SOURCE ASSESSMENT: CARBON BLACK MANUFACTURE

    EPA Science Inventory

    The report summarizes the assessment of air emissions from the manufacture of carbon black, currently manufactured in the U.S. by two major processes: thermal and oil furnace. Sources of atmospheric emissions within oil furnace plants (about 90% of the 30 U.S. carbon black plants...

  18. Mechanism of SO2 removal by carbon

    USGS Publications Warehouse

    Lizzio, A.A.; DeBarr, J.A.

    1997-01-01

    The reaction of SO2 with carbon (C) in the presence of O2 and H2O involves a series of reactions that leads to the formation of sulfuric acid as the final product. The rate-determining step in the overall process is the oxidation of SO2 to SO3. Three SO2 oxidation reactions are possible. Adsorbed SO2 (C-SO2) can react either with gas phase O2 or with adsorbed oxygen (C-O complex) to form sulfur trioxide (SO3), or gas phase SO2 can react directly with the C-O complex. In optimizing the SO2 removal capabilities of carbon, most studies only assume a given mechanism for SO2 adsorption and conversion to H2SO4 to be operable. The appropriate SO2 oxidation step and role of the C-O complex in this mechanism remain to be determined. The ultimate goal of this study was to prepare activated char from Illinois coal with optimal properties for low-temperature (80-150 ??C) removal of sulfur dioxide from coal combustion flue gas. The SO2 adsorption capacity of activated char was found to be inversely proportional to the amount of oxygen adsorbed on its surface. A temperature-programmed desorption technique was developed to titrate those sites responsible for adsorption of SO2 and conversion to H2SO4. On the basis of these results, a mechanism for SO2 removal by carbon was proposed. The derived rate expression showed SO2 adsorption to be dependent only on the fundamental rate constant and concentration of carbon atoms designated as free sites. Recent studies indicate a similar relationship exists between the rate of carbon gasification (in CO2 or H2O) and the number of reactive sites as determined by transient kinetics experiments. Utilizing the concept of active or free sites, it was possible to produce a char from Illinois coal having an SO2 adsorption capacity surpassing that of a commercial catalytic activated carbon.

  19. Biochemical Capture and Removal of Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Trachtenberg, Michael C.

    1998-01-01

    We devised an enzyme-based facilitated transport membrane bioreactor system to selectively remove carbon dioxide (CO2) from the space station environment. We developed and expressed site-directed enzyme mutants for CO2 capture. Enzyme kinetics showed the mutants to be almost identical to the wild type save at higher pH. Both native enzyme and mutant enzymes were immobilized to different supports including nylons, glasses, sepharose, methacrylate, titanium and nickel. Mutant enzyme could be attached and removed from metal ligand supports and the supports reused at least five times. Membrane systems were constructed to test CO2 selectivity. These included proteic membranes, thin liquid films and enzyme-immobilized teflon membranes. Selectivity ratios of more than 200:1 were obtained for CO2 versus oxygen with CO2 at 0.1%. The data indicate that a membrane based bioreactor can be constructed which could bring CO2 levels close to Earth.

  20. Trace elements removal from water using modified activated carbon.

    PubMed

    Campos, V; Buchler, P M

    2008-02-01

    This paper present the possible alternative options for the remove of trace elements from drinking water supplies in the trace. Arsenic and chromium are two of the most toxic pollutants, introduced into natural waters from a variety of sources and causing various adverse effects on living bodies. The performance of three filter bed methods was evaluated in the laboratory. Experiments were conducted to investigate the sorption of arsenic and chromium on carbon steel and removal of trace elements from drinking water with a household filtration process. The affinity of the arsenic and chromium species for Fe/Fe3C (iron/iron carbide) sites is the key factor controlling the removal of the elements. The method is based on the use of powdered block carbon, powder carbon steel and ceramic spheres in the ion-sorption columns as a cleaning process. The modified powdered block carbon is a satisfactory and economical sorbent for trace elements (arsenite and chromate) dissolved in water due to its low unit cost of about $23 and compatibility with the traditional household filtration system. PMID:18613611

  1. Removal of carbon-14 from irradiated graphite

    NASA Astrophysics Data System (ADS)

    Dunzik-Gougar, Mary Lou; Smith, Tara E.

    2014-08-01

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. On of the isotopes of great concern for long-term disposal of irradiated graphite is carbon-14 (14C), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates 14C is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented here is to develop a practical method by which 14C can be removed. In parallel with these efforts, the same irradiated graphite material is being characterized to identify the chemical form of 14C in irradiated graphite. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoam®, were exposed to liquid nitrogen (to increase the quantity of 14C precursor) and neutron-irradiated (1013 neutrons/cm2/s). During post-irradiation thermal treatment, graphite samples were heated in the presence of an inert carrier gas (with or without the addition of an oxidant gas), which carries off gaseous products released during treatment. Graphite gasification occurs via interaction with adsorbed oxygen complexes. Experiments in argon only were performed at 900 °C and 1400 °C to evaluate the selective removal of 14C. Thermal treatment also was performed with the addition of 3 and 5 vol% oxygen at temperatures 700 °C and 1400 °C. Thermal treatment experiments were evaluated for the effective selective removal of 14C. Lower temperatures and oxygen levels correlated to more efficient 14C removal.

  2. Removal of Volatile Organic Contaminants (VOCs) from the Groundwater Sources of Drinking Water via Granular Activated Carbon Treatment (WaterRF Report 4440)

    EPA Science Inventory

    The overall goal of this project was to assess the feasibility of granular activated carbon (GAC) for the treatment of selected carcinogenic volatile organic compounds (cVOC) to sub-μg/L levels. The project consisted of three tasks. The task objectives are: Task I - determine c...

  3. International Space Station Carbon Dioxide Removal Assembly Testing

    NASA Technical Reports Server (NTRS)

    Knox, James C.

    2000-01-01

    Performance testing of the International Space Station Carbon Dioxide Removal Assembly flight hardware in the United States Laboratory during 1999 is described. The CDRA exceeded carbon dioxide performance specifications and operated flawlessly. Data from this test is presented.

  4. Gas diffusion cell removes carbon dioxide from occupied airtight enclosures

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Small, lightweight permeable cell package separates and removes carbon dioxide from respiratory gas mixtures. The cell is regenerative while chemically inert in the presence of carbon dioxide so that only adsorption takes place.

  5. Ozone Removal by Filters Containing Activated Carbon: A Pilot Study

    SciTech Connect

    Fisk, William; Spears, Mike; Sullivan, Douglas; Mendell, Mark

    2009-09-01

    This study evaluated the ozone removal performance of moderate-cost particle filters containing activated carbon when installed in a commercial building heating, ventilating, and air conditioning (HVAC) system. Filters containing 300 g of activated carbon per 0.09 m2 of filter face area were installed in two 'experimental' filter banks within an office building located in Sacramento, CA. The ozone removal performance of the filters was assessed through periodic measurements of ozone concentrations in the air upstream and downstream of the filters. Ozone concentrations were also measured upstream and downstream of a 'reference' filter bank containing filters without any activated carbon. The filter banks with prefilters containing activated carbon were removing 60percent to 70percent of the ozone 67 and 81 days after filter installation. In contrast, there was negligible ozone removal by the reference filter bank without activated carbon.

  6. Method of removing carbon monoxide from gases

    DOEpatents

    Gerstein, Bernard C.; Macaulay, David B.

    1976-06-01

    A process and catalyst are disclosed for purifying an atmosphere containing carbon monoxide by passing the atmosphere through a bed of a catalyst of TbO.sub.x, where x = 1.8 to 1.5, which oxidizes the carbon monoxide to carbon dioxide.

  7. Removable well in reaction flask facilitates carbon dioxide collection

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Removable plastic well with a flange that seats on the rim of an Erlenmeyer screwcap flask aids quantitative collection of carbon dioxide liberated in the flask. The well can be removed without danger of cross-contamination. It can collect other gases using appropriate absorbents.

  8. Carbon injection proves effective in removing dioxins

    SciTech Connect

    Roeck, D.R.; Sigg, A.

    1996-01-01

    The last several years concerns have grown about the emission of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, both byproducts of the combustion effluent-gas stream. In Europe carbon injection is widley used to effectively control dioxin emissions from hazardous-waste incinerators. Waste Technologies Industries, a hazardous waste incinerator in Ohio, recently completed extensive testing of the effectiveness of carbon injection technology. This article discusses the testing. 1 tab.

  9. Charcoal bed operation for optimal organic carbon removal

    SciTech Connect

    Merritt, C.M.; Scala, F.R.

    1995-05-01

    Historically, evaporation, reverse osmosis or charcoal-demineralizer systems have been used to remove impurities in liquid radwaste processing systems. At Nine Mile point, we recently replaced our evaporators with charcoal-demineralizer systems to purify floor drain water. A comparison of the evaporator to the charcoal-demineralizer system has shown that the charcoal-demineralizer system is more effective in organic carbon removal. We also show the performance data of the Granulated Activated Charcoal (GAC) vessel as a mechanical filter. Actual data showing that frequent backflushing and controlled flow rates through the GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. Recommendations are provided for operating the GAC vessel to ensure optimal performance.

  10. Enhancement of nitrate removal at the sediment-water interface by carbon addition plus vertical mixing.

    PubMed

    Chen, Xuechu; He, Shengbing; Zhang, Yueping; Huang, Xiaobo; Huang, Yingying; Chen, Danyue; Huang, Xiaochen; Tang, Jianwu

    2015-10-01

    Wetlands and ponds are frequently used to remove nitrate from effluents or runoffs. However, the efficiency of this approach is limited. Based on the assumption that introducing vertical mixing to water column plus carbon addition would benefit the diffusion across the sediment-water interface, we conducted simulation experiments to identify a method for enhancing nitrate removal. The results suggested that the sediment-water interface has a great potential for nitrate removal, and the potential can be activated after several days of acclimation. Adding additional carbon plus mixing significantly increases the nitrate removal capacity, and the removal of total nitrogen (TN) and nitrate-nitrogen (NO3(-)-N) is well fitted to a first-order reaction model. Adding Hydrilla verticillata debris as a carbon source increased nitrate removal, whereas adding Eichhornia crassipe decreased it. Adding ethanol plus mixing greatly improved the removal performance, with the removal rate of NO3(-)-N and TN reaching 15.0-16.5 g m(-2) d(-1). The feasibility of this enhancement method was further confirmed with a wetland microcosm, and the NO3(-)-N removal rate maintained at 10.0-12.0 g m(-2) d(-1) at a hydraulic loading rate of 0.5 m d(-1). PMID:25556005

  11. Selective Oxidizer For Removal Of Carbon Monoxide

    NASA Technical Reports Server (NTRS)

    Trocciola, John C.; Schroll, Craig R.; Lesieur, Roger R.

    1996-01-01

    Catalytic apparatus selectively oxidizes most of carbon monoxide (without oxidizing hydrogen) in stream of reformed fuel gas fed to low-temperature fuel cell. Multiple catalytic stages at progressively lower temperatures operate without becoming poisoned. Catalysts used to oxidize CO selectively include platinum on alumina and commercial catalyst known as "Selectoxo."

  12. Adsorptive removal of antibiotics from aqueous solution using carbon materials.

    PubMed

    Yu, Fei; Li, Yong; Han, Sheng; Ma, Jie

    2016-06-01

    Antibiotics, an important type of environmental contamination, have attracted many researchers to the study of their removal from aqueous solutions. Adsorption technology is a fast, efficient, and economical physicochemical method that is extensively used in wastewater treatment. From original activated carbon and carbon nanotubes to the latest graphene-based materials, carbon-based materials have been widely used as highly effective adsorbents for contaminant removal from aqueous solution because of their large specific surface area, high porosity, and high reaction activity. In this article, adsorption removal methods for four major types of antibiotic (tetracyclines, sulfonamides, macrolides, and quinolones) are reviewed. We also provide an overview of the application development of carbon materials as adsorbents for antibiotic removal from aqueous solution. The most promising works are discussed, and the main challenges in preparing high-performance adsorbents and the development tendency of adsorbents are also analyzed. This work provides theoretical guidance for subsequent research in the design and modification of carbon materials for applications in the adsorption removal of antibiotics from aqueous solution. PMID:27031800

  13. Comparison of pre- and post-combustion carbon removal

    SciTech Connect

    Morris, S.C.; Lee, J.; Goldstein, G.; Steinberg, M.

    1992-06-01

    Conventional approaches to reduce CO{sub 2} emissions, including fuel switching among fossil fuels, renewables, nuclear, end-use conservation, and increased efficiency, nearly all lead to reduction in coal use. Carbon removal technologies along have the potential to allow continued use of coal. All approaches must compete economically, technically, and environmentally for market share within the context of the total energy system. MARKAL, a dynamic energy systems model, was used to simulate this competition through 2025 for the US energy system. Three carbon removal technologies were evaluated: CO{sub 2} scrubbing from coal-fired power plant flue gas, CO{sub 2} separation during coal gasification, and carbon separation in the Hydrocarb process. CO{sub 2} was sequestered in depleted gas wells and the deep ocean, and solid carbon in depleted coal mines. All three technologies evaluated offer a more cost-effective path to CO{sub 2} emission reduction than the reference case. Moreover, the ability of pre-combustion methods of carbon removal can be combined with producing motor fuels as well as electric power fuels, a combination that provided greater opportunity for carbon removal.

  14. Comparison of pre- and post-combustion carbon removal

    SciTech Connect

    Morris, S.C.; Lee, J.; Goldstein, G.; Steinberg, M.

    1992-01-01

    Conventional approaches to reduce CO{sub 2} emissions, including fuel switching among fossil fuels, renewables, nuclear, end-use conservation, and increased efficiency, nearly all lead to reduction in coal use. Carbon removal technologies along have the potential to allow continued use of coal. All approaches must compete economically, technically, and environmentally for market share within the context of the total energy system. MARKAL, a dynamic energy systems model, was used to simulate this competition through 2025 for the US energy system. Three carbon removal technologies were evaluated: CO{sub 2} scrubbing from coal-fired power plant flue gas, CO{sub 2} separation during coal gasification, and carbon separation in the Hydrocarb process. CO{sub 2} was sequestered in depleted gas wells and the deep ocean, and solid carbon in depleted coal mines. All three technologies evaluated offer a more cost-effective path to CO{sub 2} emission reduction than the reference case. Moreover, the ability of pre-combustion methods of carbon removal can be combined with producing motor fuels as well as electric power fuels, a combination that provided greater opportunity for carbon removal.

  15. Removal of benzocaine from water by filtration with activated carbon

    USGS Publications Warehouse

    Howe, G.E.; Bills, T.D.; Marking, L.L.

    1990-01-01

    Benzocaine is a promising candidate for registration with the U.S. Food and Drug Administration for use as an anesthetic in fish culture, management, and research. A method for the removal of benzocaine from hatchery effluents could speed registration of this drug by eliminating requirements for data on its residues, tolerances, detoxification, and environmental hazards. Carbon filtration effectively removes many organic compounds from water. This study tested the effectiveness of three types of activated carbon for removing benzocaine from water by column filtration under controlled laboratory conditions. An adsorptive capacity was calculated for each type of activated carbon. Filtrasorb 400 (12 x 40 mesh; U.S. standard sieve series) showed the greatest capacity for benzocaine adsorption (76.12 mg benzocaine/g carbon); Filtrasorb 300 (8 x 30 mesh) ranked next (31.93 mg/g); and Filtrasorb 816 (8 x 16 mesh) absorbed the least (1.0 mg/g). Increased adsorptive capacity was associated with smaller carbon particle size; however, smaller particle size also impeded column flow. Carbon filtration is a practical means for removing benzocaine from treated water.

  16. Ammonium removal in constructed wetland microcosms as influenced by season and organic carbon load.

    PubMed

    Riley, Kate A; Stein, Otto R; Hook, Paul B

    2005-01-01

    We evaluated ammonium nitrogen removal and nitrogen transformations in three-year-old, batch-operated, subsurface wetland microcosms. Treatments included replicates of Typha latifolia, Carex rostrata, and unplanted controls when influent carbon was excluded, and C. rostrata with an influent containing organic carbon. A series of 10-day batch incubations were conducted over a simulated yearlong cycle of seasons. The presence of plants significantly enhanced ammonium removal during both summer (24 degrees C, active plant growth) and winter (4 degrees C, plant dormancy) conditions, but significant differences between plant species were evident only in summer when C. rostrata outperformed T. latifolia. The effect of organic carbon load was distinctly seasonal, enhancing C. rostrata ammonium removal in winter but having an inhibitory effect in summer. Season did not influence ammonium removal in T. latifolia or unplanted columns. Net production of organic carbon was evident year-round in units without an influent organic carbon source, but was enhanced in summer, especially for C. rostrata, which produced significantly more than T. latifolia and unplanted controls. No differences in production were evident between species in winter. COD values for C. rostrata microcosms with and without influent organic carbon converged within 24 hours in winter and 7 days in summer. Gravel sorption, microbial immobilization and sequential nitrification/denitrification appear to be the major nitrogen removal mechanisms. All evidence suggests differences between season and species are due to differences in seasonal variation of root-zone oxidation. PMID:15921269

  17. Removal of H2S using molten carbonate at high temperature.

    PubMed

    Kawase, Makoto; Otaka, Maromu

    2013-12-01

    Gasification is considered to be an effective process for energy conversion from various sources such as coal, biomass, and waste. Cleanup of the hot syngas produced by such a process may improve the thermal efficiency of the overall gasification system. Therefore, the cleanup of hot syngas from biomass gasification using molten carbonate is investigated in bench-scale tests. Molten carbonate acts as an absorbent during desulfurization and dechlorination and as a thermal catalyst for tar cracking. In this study, the performance of molten carbonate for removing H2S was evaluated. The temperature of the molten carbonate was set within the range from 800 to 1000 °C. It is found that the removal of H2S is significantly affected by the concentration of CO2 in the syngas. When only a small percentage of CO2 is present, desulfurization using molten carbonate is inadequate. However, when carbon elements, such as char and tar, are continuously supplied, H2S removal can be maintained at a high level. To confirm the performance of the molten carbonate gas-cleaning system, purified biogas was used as a fuel in power generation tests with a molten carbonate fuel cell (MCFC). The fuel cell is a high-performance sensor for detecting gaseous impurities. When purified gas from a gas-cleaning reactor was continuously supplied to the fuel cell, the cell voltage remained stable. Thus, the molten carbonate gas-cleaning reactor was found to afford good gas-cleaning performance. PMID:24035726

  18. Removal of phenolic estrogen pollutants from different sources of water using molecularly imprinted polymeric microspheres.

    PubMed

    Lin, Yi; Shi, Yun; Jiang, Ming; Jin, Yuan; Peng, Yan; Lu, Bin; Dai, Kang

    2008-05-01

    The efficiency and effects of using Bisphenol A-molecularly imprinted polymeric microspheres (MIPMs) to remove phenolic estrogens from different sources of water were evaluated. MIPMs prepared by precipitation polymerization removed a group of phenolic estrogens from different kinds of water selectively and effectively. The highest removal efficiency was observed at pH=5. Fifty millimoles per litre ions or 10mg/L humid acid improved removal efficiency. MIPMs were more suitable to remove trace estrogens in large volume than high concentration of estrogens in small volume. The removal efficiency of spiked tap water, lake water and river water were better than that of distilled water. Hundred milligrams of MIPMs had higher removal selectivity and efficiency than those of 100mg or 300mg activated carbons. Moreover, MIPMs can be re-used for at least 30 times without losing any removal efficiency. MIPMs provided a selective, simple, reliable and practicable solution to remove trace phenolic estrogens from different sources of water. PMID:17870222

  19. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    2014-08-19

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  20. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    2010-11-09

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  1. Enriching blast furnace gas by removing carbon dioxide.

    PubMed

    Zhang, Chongmin; Sun, Zhimin; Chen, Shuwen; Wang, Baohai

    2013-12-01

    Blast furnace gas (BF gas) produced in the iron making process is an essential energy resource for a steel making work. As compared with coke oven gas, the caloric value of BF gas is too low to be used alone as fuel in hot stove because of its high concentrations of carbon dioxide and nitrogen. If the carbon dioxide in BF gas could be captured efficiently, it would meet the increasing need of high caloric BF gas, and develop methods to reusing and/or recycling the separated carbon dioxide further. Focused on this, investigations were done with simple evaluation on possible methods of removing carbon dioxide from BF gas and basic experiments on carbon dioxide capture by chemical absorption. The experimental results showed that in 100 minutes, the maximum absorbed doses of carbon dioxide reached 20 g/100 g with ionic liquid as absorbent. PMID:25078829

  2. Source of released carbon fibers

    NASA Technical Reports Server (NTRS)

    Bell, V. L.

    1979-01-01

    The potential for the release of carbon fibers from aircraft crashes/fires is addressed. Simulation of the conditions of aircraft crash fires in order to predict the quantities and forms of fibrous materials which might be released from civilian aircraft crashes/fires is considered. Figures are presented which describe some typical fiber release test activities together with some very preliminary results of those activities. The state of the art of carbon fiber release is summarized as well as some of the uncertainties concerning accidental fiber release.

  3. Are Glaciers and Ice Sheets Carbon Sources or Carbon Sinks?

    NASA Astrophysics Data System (ADS)

    Graly, J. A.; Drever, J. I.; Humphrey, N. F.

    2014-12-01

    Subglacial waters typically contain considerable quantities of HCO3-. Where this HCO3- is coupled with Ca2+ and Mg2+, it will ultimately precipitate as (Ca, Mg)CO3 in the oceans. If the glacial HCO3- is derived from atmospheric CO2, this pathway represents a long-term CO2 sink. If the HCO3- is derived from carbonate minerals, precipitation is equal to dissolution and there is no net effect on the CO2 balance of the atmosphere. Only the weathering of Ca or Mg-bearing silicates can potentially draw CO2 out of the ocean/atmosphere system. Subglacial environments are potential habitats for a range of microbes that may generate CO2 from organic C. If the production of CO2 from organic sources exceeds the weathering of Ca and Mg from silicates, the subglacial environment is a long-term CO2 source. In order to determine whether ice bodies typically act as CO2 sources or sinks, we modeled the evolution of pH and alkalinity through a range of typical subglacial weathering reactions, considering both the case in which CO2 and O2 can openly exchange with the atmosphere and the case in which the subglacial environment is closed from atmospheric interaction. We find that in the closed system scenario, subglacial waters cannot reach atmospheric PCO2 levels under typical conditions. Initial open system weathering followed by closed system weathering can allow CO2 supersaturation when sulfide oxidation is considered. We use this result to analyze pH and alkalinity measurements from a geographically and geologically diverse selection of subglacial waters. The PCO2 of most of the subglacial waters is near or above atmospheric values. This implies that exchange of gases between subglacial waters and the atmosphere is typical and widespread. This input of atmospheric CO2 into the glacial weathering environment implies that about 5 mg of CO2 are typically removed from the atmosphere per l of glacial discharge water. Similar PCO2 values can be produced in an entirely closed system if

  4. Biotechnology for removal of carbon disulfide emissions. Final report

    SciTech Connect

    McIntosh, M.J.

    1995-07-01

    Biological removal in a ``biofilter`` plant of carbon disulfide and hydrogen sulfide from the air effluent of a viscose plant at Teepak, Inc., is analyzed from process and economic standpoints by use of the Aspen Plus simulation program. The metabolic product from the biofilter, 3% sulfuric acid, must be transformed at the source into either a marketable or recyclable commodity (such as 95% sulfuric acid, high-quality sulfur, or high-quality gypsum) or a material with reasonable landfill costs (such as sulfur or gypsum). The simulations indicate that the total capital requirement for production of concentrated sulfuric acid is $48.9 million; for high-quality gypsum, $40.4 million; and for high-quality sulfur, $29.4 million. Production of concentrated sulfur for landfill is not economically practical. The process to neutralize the 3% acid effluent with limestone and landfill the resulting low-quality gypsum requires the lowest total investment of the processes simulated, $8.7 million, including the biofilter plant.

  5. TRIHALOMETHANE PRECURSOR REMOVAL BY THE MAGNESIUM CARBONATE PROCESS

    EPA Science Inventory

    A project was conducted to determine and improve the ability of the magnesium carbonate process to remove trihalomethane (THM) precursors in treated drinking water. The project was conducted at a drinking water treatment plant in Melbourne, FL, which had been developed and instal...

  6. Copper crystallite in carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1993-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfurfuryl alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  7. Copper modified carbon molecular sieves for selective oxygen removal

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Seshan, Panchalam K. (Inventor)

    1992-01-01

    Carbon molecular sieves modified by the incorporation of finely divided elemental copper useful for the selective sorption of oxygen at elevated temperatures. The carbon molecular sieves can be regenerated by reduction with hydrogen. The copper modified carbon molecular sieves are prepared by pyrolysis of a mixture of a copper-containing material and polyfunctional alcohol to form a sorbent precursor. The sorbent precursors are then heated and reduced to produce copper modified carbon molecular sieves. The copper modified carbon molecular sieves are useful for sorption of all concentrations of oxygen at temperatures up to about 200.degree. C. They are also useful for removal of trace amount of oxygen from gases at temperatures up to about 600.degree. C.

  8. Aqueous adsorption and removal of organic contaminants by carbon nanotubes.

    PubMed

    Yu, Jin-Gang; Zhao, Xiu-Hui; Yang, Hua; Chen, Xiao-Hong; Yang, Qiaoqin; Yu, Lin-Yan; Jiang, Jian-Hui; Chen, Xiao-Qing

    2014-06-01

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. PMID:24657369

  9. Removal of dissolved natural organic matter from source water with alum coagulation.

    PubMed

    Wang, C S; Kang, S F; Yang, H J; Pa, S Y; Chen, H W

    2002-12-01

    In this study, the effectiveness of enhanced alum coagulation for removal of natural organic matter (NOM) at various alum dosages and pH conditions was assessed for three source waters. Results from the laboratory jar tests at various conditions were compared. Tested pH ranged from 5.0 to 8.0, with alum dosages ranging from 60-120 mg l(-1) for removal of dissolved NOM with various concentration of dissolved organic carbon (DOC) and alkalinity. Alum coagulation profiles of the three source waters were also compared. For Cheng-Kung Water Treatment Plant (high DOC, high alkalinity), laboratory tests showed 50% DOC removal with alum dosage of 70-110 mg (-1). after acidifying the raw water to pH = 6. For Tai Lake Water Treatment Plant (high DOC, low alkalinity), laboratory tests showed that the highest DOC removal (approximately 50%) was achieved at an alum dosage of 80 mg l(-1) at pH = 8 (natural condition). However, alum coagulation showed little DOC removal for source water from Kee-Lung River (low DOC, low alkalinity). Higher alkalinity in Cheng-Kung Reservoir accounts for the necessity to acidify the raw water before enhanced coagulation for optimum DOC removal. PMID:12523512

  10. Removal of H{sub 2}S using molten carbonate at high temperature

    SciTech Connect

    Kawase, Makoto Otaka, Maromu

    2013-12-15

    Highlights: • The performance of molten carbonate for the removal of H{sub 2}S improves at higher temperatures. • The degree of H{sub 2}S removal is significantly affected by the CO{sub 2} concentration in syngas. • Addition of carbon elements, such as char and tar, decrease the negative effects of CO{sub 2}. • Continuous addition of carbon elements into molten carbonate enables continuous desulfurization. • Desulfurization using molten carbonate is suitable for gasification gas. - Abstract: Gasification is considered to be an effective process for energy conversion from various sources such as coal, biomass, and waste. Cleanup of the hot syngas produced by such a process may improve the thermal efficiency of the overall gasification system. Therefore, the cleanup of hot syngas from biomass gasification using molten carbonate is investigated in bench-scale tests. Molten carbonate acts as an absorbent during desulfurization and dechlorination and as a thermal catalyst for tar cracking. In this study, the performance of molten carbonate for removing H{sub 2}S was evaluated. The temperature of the molten carbonate was set within the range from 800 to 1000 °C. It is found that the removal of H{sub 2}S is significantly affected by the concentration of CO{sub 2} in the syngas. When only a small percentage of CO{sub 2} is present, desulfurization using molten carbonate is inadequate. However, when carbon elements, such as char and tar, are continuously supplied, H{sub 2}S removal can be maintained at a high level. To confirm the performance of the molten carbonate gas-cleaning system, purified biogas was used as a fuel in power generation tests with a molten carbonate fuel cell (MCFC). The fuel cell is a high-performance sensor for detecting gaseous impurities. When purified gas from a gas-cleaning reactor was continuously supplied to the fuel cell, the cell voltage remained stable. Thus, the molten carbonate gas-cleaning reactor was found to afford good gas

  11. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film.

    PubMed

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong

    2016-09-01

    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone. PMID:27501513

  12. Experimental study for carbon dioxide removal system in space station

    SciTech Connect

    Etoh, T.; Nihei, T.; Otsuji, K.; Satoh, S.; Hatano, S.

    1987-01-01

    As the result of the human metabolism in the space station, the carbon dioxide is discharged into the cabin atmosphere. It is indispensable to remove the carbon dioxide and keep it below the allowable level for the life support in a closed environment. The regenerative carbon dioxide removal system is necessary for the space station to decrease the life-cycle cost. The Solid Amine Water Desorbed (SAWD) system is considered as a competitive option among several candidate systems. In the SAWD process, the carbon dioxide gas is adsorbed by the ion-exchange-type solid amine, which is bedded in the canisters, and desorbed by heating the solid amine with the direct steam flow. The adsorption and desorption stage of the canisters are proceeded alternatively by the automatic control. For the application in the space station, the SAWD system shall embody less resources as well as high performance and reliability. In the space station operated on the orbit for long periods of time, the replenishment cost of the resupplies using the Space Transportation System (STS) is very expensive. Therefore, the self-sufficient system should be developed by making the material cycle closed in the space station. Especially, the closed cycle of the materials such as H/sub 2/0, O/sub 2/, N/sub 2/ and Carbon (i.e., foods) should be studied. For the extended operational capability of the Japanese Experimental Module (JEM), the closed cycle of oxygen is investigated. The system combined with CO/sub 2/ removal, CO/sub 2/ reduction and O/sub 2/ generation is studied as the candidate technology for the oxygen closed cycle. The fundamental investigation and testing regarding CO/sub 2/ removal system were performed. As the result, it was confirmed that the solid amine water desorbed (SAWD) system is very excellent.

  13. Role of HF in oxygen removal from carbon nanotubes: implications for high performance carbon electronics.

    PubMed

    Li, Xiaokai; Huang, Jing-Shun; Nejati, Siamak; McMillon, Lyndsey; Huang, Su; Osuji, Chinedum O; Hazari, Nilay; Taylor, André D

    2014-11-12

    Oxygen removal from SWNTs is crucial for many carbon electronic devices. This work shows that HF treatment followed by current stimulation is a very effective method for oxygen removal. Using a procedure involving HF treatment, current stimulation and spin-casting AgNWs onto a SWNT thin film, record high efficiency SWNT/p-Si solar cells have been developed. PMID:25286024

  14. Method for removal of nitrogen oxides from stationary combustion sources

    NASA Technical Reports Server (NTRS)

    Cooper, Charles D. (Inventor); Clausen, III, Christian A. (Inventor); Collins, Michelle M. (Inventor)

    2004-01-01

    A method for removing NO.sub.X from gas streams emanating from stationary combustion sources and manufacturing plants utilizes the injection of hydrogen peroxide into the gas stream for rapid gas-phase oxidation of NO to NO.sub.2 and water-soluble nitrogen acids HNO.sub.2 and HNO.sub.3. The nitrogen acids may be removed from the oxidized gas stream by wet scrubbing or by contact with a particulate alkaline material to form a nitrite/nitrate salt.

  15. A Fluorescent Source NDIR Carbon Monoxide Analyzer

    NASA Technical Reports Server (NTRS)

    Link, W. T.; McClatchie, E. A.; Watson, D. A.; Compher, A. B.

    1971-01-01

    This paper describes a new technique for measuring trace quantities of carbon monoxide by the nondispersive infrared (NDIR) methods. The technique uses the property of infrared fluorescence in a gas to generate a specific source of radiation which is an exact match of the absorption spectrum of the fundamental band of carbon monoxide. This results in an instrument with high sensitivity and specificity for CO. A novel method of referencing using an isotopic species of CO confers great stability on the instrument.

  16. Estimating organic micro-pollutant removal potential of activated carbons using UV absorption and carbon characteristics.

    PubMed

    Zietzschmann, Frederik; Altmann, Johannes; Ruhl, Aki Sebastian; Dünnbier, Uwe; Dommisch, Ingvild; Sperlich, Alexander; Meinel, Felix; Jekel, Martin

    2014-06-01

    Eight commercially available powdered activated carbons (PAC) were examined regarding organic micro-pollutant (OMP) removal efficiencies in wastewater treatment plant (WWTP) effluent. PAC characteristic numbers such as B.E.T. surface, iodine number and nitrobenzene number were checked for their potential to predict the OMP removal of the PAC products. Furthermore, the PAC-induced removal of UV254 nm absorption (UVA254) in WWTP effluent was determined and also correlated with OMP removal. None of the PAC characteristic numbers can satisfactorily describe OMP removal and accordingly, these characteristics have little informative value on the reduction of OMP concentrations in WWTP effluent. In contrast, UVA254 removal and OMP removal correlate well for carbamazepine, diclofenac, and several iodinated x-ray contrast media. Also, UVA254 removal can roughly describe the average OMP removal of all measured OMP, and can accordingly predict PAC performance in OMP removal. We therefore suggest UVA254 as a handy indicator for the approximation of OMP removal in practical applications where direct OMP concentration quantification is not always available. In continuous operation of large-scale plants, this approach allows for the efficient adjustment of PAC dosing to UVA254, in order to ensure reliable OMP removal whilst minimizing PAC consumption. PMID:24651017

  17. Ecological Limits to Terrestrial Biological Carbon Dioxide Removal

    NASA Astrophysics Data System (ADS)

    Torn, M. S.; Smith, L. J.; Mishra, U.; Sanchez, D.; Williams, J.

    2014-12-01

    Many climate change mitigation scenarios include terrestrial atmospheric carbon dioxide removal (BCDR) or carbon neutral bioenergy production through bioenergy with carbon capture and storage (BECS) or afforestation/reforestation. Very high sequestration potentials for these strategies have been reported, and we evaluate the potential ecological limits (e.g., land and resource requirements) to implementation at the 1 Pg C y-1 scale relevant to climate change mitigation for U.S. and global scenarios. We estimate that removing 1 Pg C y-1 via tropical afforestation would require at least 7×106 ha y-1 of land, 0.09 Tg y-1 of nitrogen, and 0.2 Tg y-1 of phosphorous, and would increase evapotranspiration from those lands by almost 50%. Because of improved carbon capture technologies, we are updating (and reducing) our previous estimates for switchgrass BECS (previous estimate was 2×108 ha land and 20 Tg y-1 of nitrogen (20 % of global fertilizer nitrogen production)). Miscanthus could meet the same biomass production with much lower N demand. Moreover, transitioning the U.S land currently under corn- ethanol production to no-till perennial grasses for bioenergy would meet U.S. needs and have additional environmental benefits (such as improved wildlife habitat and soil restoration). Thus, there are both signficant ecological limits to BCDR as well as potential ecological benefits, depending on implementation.

  18. Application of plant carbon source for denitrification by constructed wetland and bioreactor: review of recent development.

    PubMed

    Hang, Qianyu; Wang, Haiyan; Chu, Zhaosheng; Ye, Bibi; Li, Chunmei; Hou, Zeying

    2016-05-01

    Water quality standard for nitrate becomes more and more strict, and the plant carbon source is widely used for denitrification by constructed wetland (CW) and bioreactor. However, the nitrate removal efficiency by different types of plant carbon source are not evaluated comprehensively. Denitrification performance of different plant carbon sources, and the influence of dosing method and pretreatment are thoroughly reviewed in this paper, which aims to investigate the accurate utilization of plant carbon source for nitrogen (as nitrate) removal. It is concluded that plant carbon source addition for all types of CWs and bioreactors can improve the nitrate removal efficiency to some extent, and the dosing method of plant carbon source for denitrification should be further studied and optimized in the future. The popular carbon sources for CW and bioreactor denitrification enhancement are woodchip, chopped macrophytes, crop plants, macrophytes litters, etc. The recommended optimum C:N ratios for CW and bioreactor are 4.0:5.0 and 1.8:3.0, respectively. The physical and biological pretreatments are selected to supply organic carbon for long-term denitrification. PMID:26971521

  19. Carbon source dependent promoters in yeasts

    PubMed Central

    2014-01-01

    Budding yeasts are important expression hosts for the production of recombinant proteins. The choice of the right promoter is a crucial point for efficient gene expression, as most regulations take place at the transcriptional level. A wide and constantly increasing range of inducible, derepressed and constitutive promoters have been applied for gene expression in yeasts in the past; their different behaviours were a reflection of the different needs of individual processes. Within this review we summarize the majority of the large available set of carbon source dependent promoters for protein expression in yeasts, either induced or derepressed by the particular carbon source provided. We examined the most common derepressed promoters for Saccharomyces cerevisiae and other yeasts, and described carbon source inducible promoters and promoters induced by non-sugar carbon sources. A special focus is given to promoters that are activated as soon as glucose is depleted, since such promoters can be very effective and offer an uncomplicated and scalable cultivation procedure. PMID:24401081

  20. Carbon source in the future chemical industries

    NASA Astrophysics Data System (ADS)

    Hofmann, Peter; Heinrich Krauch, Carl

    1982-11-01

    Rising crude oil prices favour the exploitation of hitherto unutilised energy carriers and the realisation of new technologies in all sectors where carbon is used. These changed economic constraints necessitate both savings in conventional petrochemistry and a change to oil-independent carbon sources in the chemical industry. While, in coal chemistry, the synthesis and process principles of petrochemistry — fragmentation of the raw material and subsequent buildup of molecular structures — can be maintained, the raw material structure largely remains unchanged in the chemistry of renewable raw materials. This lecture is to demonstrate the structural as well as the technological and energy criteria of the chemistry of alternative carbon sources, to forecast the chances of commercial realization and to discuss some promising fields of research and development.

  1. Comparison of aerobic denitrifying activity among three cultural species with various carbon sources.

    PubMed

    Otani, Y; Hasegawa, K; Hanaki, K

    2004-01-01

    Abilities of three aerobic denitrifiers such as Alcaligenes faecalis, Microvirgula aerodenitrificans and Paracoccus pantotrophus were compared from the viewpoints of nitrate removal efficiency and organic matter utilization. First, the effect of carbon source was investigated. Although nitrate reduction was observed in all strains under aerobic conditions, a change of carbon source considerably affected the denitrification ability. In the case of P. pantotrophus, nitrate and nitrite were completely removed in three days under sodium acetate or leucine as a carbon source. In the case of A. faecalis, sufficient nitrate removal was observed only when sodium acetate or ethanol was added. P. pantotrophus and A. faecalis showed a higher ability of nitrate removal than that of M. aerodenitrificans. Therefore, P. pantotrophus was selected in order to investigate the effects of concentration and repetitive addition of carbon. Sodium acetate was used as a sole carbon source. Nitrate was not reduced when the carbon concentration was below 500 mgC/L. However, when carbon source was added repeatedly, nitrate was reduced under 100 mgC/L after the optical density of the bacterium reached above 1.0. This result indicated that a high enough level of bacterial density was necessary to express aerobic denitrification activity. PMID:15566182

  2. Removal of toxic chemicals from water with activated carbon

    USGS Publications Warehouse

    Dawson, V.K.; Marking, L.L.; Bills, T.D.

    1976-01-01

    Activated carbon was effective in removing fish toxicants and anesthetics from water solutions. Its capacity to adsorb 3-trifluoromethyl-4-nitrophenol (TFM), antimycin, NoxfishA? (5% rotenone), Dibrorms, juglone, MSa??222, and benzocaine ranged from 0.1 to 64 mg per gram of carbon. The adsorptive capacity (end point considered as a significant discharge) of activated carbon for removal of TFM was determined at column depths of 15, 30, and 60 cm; temperatures of 7, 12, 17, and 22 C; pH's of 6.5, 7.5, 8.5, and 9.5; and flow rates of 50, 78, 100, 200, and 940 ml/min. Adsorptive capacity increased when the contact time was increased by reducing the flow rate or increasing the column depth. The adsorptive capacity was not significantly influenced by temperature but was substantially higher at pH 6.5 than at the other pH's tested. A practical and efficient filter for purifying chemically treated water was developed.

  3. Removal of organic impurities from liquid carbon dioxide

    NASA Astrophysics Data System (ADS)

    Zito, Richard R.

    2002-09-01

    The use of a high velocity stream of carbon dioxide snowflakes to clean large optics is well known, and has gained widespread acceptance in the astronomical community as a telescope maintenance technique. Ultimately, however, the success of carbon dioxide snow cleaning depends on the availability of high purity carbon dioxide. The higher the purity of the carbon dioxide, the longer will be the time interval between required mirror washings. The highest grades of commercially produced liquid carbon dioxide are often not available in the more remote regions of the world - such as where major astronomical observatories are often located. Furthermore, the purity of even the highest grades of carbon dioxide are only nominal, and wide variations are known to occur from tank to tank. Occasionally, visible deposits of organic impurities are left behind during cleaning with carbon dioxide that is believed to be 99.999% pure. A zeolite molecular sieve based filtration system has proven to be very effective in removing these organic impurities. A zeolite is a complex alumino-silicate. One example has an empirical formula of Na2O(Al2O3)(SiO2)2yH2O, where y=0 to 8. The zeolites have an open crystal structure and are capable of trapping impurities like 8-methylheptadecane (an oil) and 2,6-octadine-1-ol,3,7- dimethyl-,(E)- (a fatty acid). In fact, a zeolite can trap 29.5% of its own weight in SAE 20 lubricant at 25 degree(s)C. After filtration of liquid CO2 through zeolites, the concentration of measured impurities was below the detection limit for state-of-the-art gas chromatography systems.

  4. 10 CFR 35.404 - Surveys after source implant and removal.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Surveys after source implant and removal. 35.404 Section... § 35.404 Surveys after source implant and removal. (a) Immediately after implanting sources in a... sources that have not been implanted. (b) Immediately after removing the last temporary implant...

  5. 10 CFR 35.404 - Surveys after source implant and removal.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Surveys after source implant and removal. 35.404 Section... § 35.404 Surveys after source implant and removal. (a) Immediately after implanting sources in a... sources that have not been implanted. (b) Immediately after removing the last temporary implant...

  6. 10 CFR 35.404 - Surveys after source implant and removal.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Surveys after source implant and removal. 35.404 Section... § 35.404 Surveys after source implant and removal. (a) Immediately after implanting sources in a... sources that have not been implanted. (b) Immediately after removing the last temporary implant...

  7. 10 CFR 35.404 - Surveys after source implant and removal.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Surveys after source implant and removal. 35.404 Section... § 35.404 Surveys after source implant and removal. (a) Immediately after implanting sources in a... sources that have not been implanted. (b) Immediately after removing the last temporary implant...

  8. 10 CFR 35.404 - Surveys after source implant and removal.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Surveys after source implant and removal. 35.404 Section... § 35.404 Surveys after source implant and removal. (a) Immediately after implanting sources in a... sources that have not been implanted. (b) Immediately after removing the last temporary implant...

  9. Removal of dispersant-stabilized carbon nanotubes by regular coagulants.

    PubMed

    Liu, Ni; Liu, Changli; Zhang, Jing; Lin, Daohui

    2012-01-01

    Coagulation followed by sedimentation, as a conventional technique in the water treatment plant, can be the first line of defense against exposures of carbon nanotubes (CNTs) to aquatic organisms and human beings, which has been rarely documented. This study investigated the removal of dispersant-stabilized CNT suspensions by poly aluminum chloride (PACl) and KAl(SO4)2 x 12H2O (alum), with a focus on the effects of dispersant type, coagulant type and dosage. PACl performed better than alum in the removal of tannic acid-, humic acid-, and sodium dodecyl benzenesulfonate-stabilized CNTs, but worse for polyethylene glycol octylphenyl ether (TX100)-stabilized CNTs. Neither coagulant could effectively precipitate cetyltrimethyl ammonium bromide-stabilized CNTs. The removal by PACl first increased up to a plateau and then decreased with the continued increase of coagulant dosage. However, the removal rates leveled off but did not decrease after achieving their highest level with the continued addition of alum. The coagulation and flocculation of the CNT suspensions by PACl could be regulated mainly by the mechanism of adsorption charge neutralization, whereas the coagulation by alum mainly involved electrical double-layer compression. PMID:23513676

  10. Removal of mercury from stack gases by activated carbon

    SciTech Connect

    Vidic, R.D.

    1995-10-01

    On combustion, the trace elements in the incinerator feed stream are partitioned between the bottom ash (slag) stream, and a flue gas stream containing suspended fly ash and vapors of volatile elements or compounds. A further partitioning of the flue gas stream takes place in the particulate emission control devices that efficiently remove larger fly ash particles but are less efficient for vapors and finer particles. Environmental control agencies, researchers, and general public have become increasingly concerned with the mobilization of trace elements to the environment from solid and hazardous waste incinerators. Mercury is the trace element of particular concern since, during combustion, most of the mercury present in the influent stream is transferred into the vapor phase due to its high volatility. There is a considerable evidence in the literature that currently used pollution abatement technologies (flue gas clean-up and particulate control devices) are not capable of controlling gas phase mercury emissions. Activated carbon adsorption is a unit process that offers great promise for achieving high quality air emissions with respect to mercury and other trace elements that might be present in gases emitted from solid and hazardous waste incinerators. This study is designed to evaluate the rate of vapor-phase mercury removal by virgin and sulfur impregnated activated carbons under various process conditions. The specific process conditions that will be evaluated for their effect on the rate and mechanism of mercury uptake include temperature, moisture content, oxygen partial pressure, and presence of other compounds and trace elements in the vapor-phase. Accurate description of the kinetics of mercury removal by activated carbon is an essential component in establishing design procedures that would ensure successful application of this efficient technology for mercury control.

  11. Geolocating Russian sources for Arctic black carbon

    NASA Astrophysics Data System (ADS)

    Cheng, Meng-Dawn

    2014-08-01

    To design and implement an effective emission control strategy for black carbon (BC), the locations and strength of BC sources must be identified. Lack of accurate source information from the Russian Federation has created difficulty for a range of research and policy activities in the Arctic because Russia occupies the largest landmass in the Arctic Circle. A project was initiated to resolve emission sources of BC in the Russian Federation by using the Potential Source Contribution Function (PSCF). It used atmospheric BC data from two Arctic sampling stations at Alert Nunavut, Canada, and Tiksi Bay, Russia. The geographical regions of BC emission sources in Russia were identified and summarized as follows: (1) a region surrounding Moscow, (2) regions in Eurasia stretching along the Ural Mountains from the White Sea to the Black Sea, and (3) a number of scattered areas from western Siberia to the Russian Far East. Particulate potassium ions, non-marine sulfate, and vanadium were used to assist in resolving the source types: forest fire/biomass burning, coal-fired power plant, and oil combustion. Correlating these maps with the BC map helped to resolve source regions of BC emissions and connect them to their corresponding source types. The results imply that a region south of Moscow and another north of the Ural Mountains could be significant BC sources, but none of the grid cells in these regions could be linked to forest fires, oil combustion, or coal-fired power plants based on these three markers.

  12. Carbon nanotube electron sources for electron microscopes

    SciTech Connect

    De Jonge, Niels

    2009-01-01

    Electron sources were made from individual multi-walled carbon nanotubes with closed caps and thoroughly cleaned surfaces. Nanotubes from both chemical vapor deposition growth and arc discharge growth were investigated. These emitters provide a highly stable emission current up to a threshold current of a few microamperes. At too large currents several processes take place such as splitting, breaking and cap closing. The emission process is field emission for a workfunction of 5 eV. The electron optical per-formance is highly beneficial for their use as high-brightness point sources in electron microscopes and advantageous with respect to state-of-the-art electron sources. The life-time is at least two years. We have tested the source successfully in a scanning electron microscope.

  13. Rapid removal of bisphenol A on highly ordered mesoporous carbon.

    PubMed

    Sui, Qian; Huang, Jun; Liu, Yousong; Chang, Xiaofeng; Ji, Guangbin; Deng, Shubo; Xie, Tao; Yu, Gang

    2011-01-01

    Bisphenol A (BPA) is of global concern due to its disruption of endocrine systems and ubiquity in the aquatic environment. It is important, therefore, that efforts are made to remove it from the aqueous phase. A novel adsorbent, mesoporous carbon CMK-3, prepared from hexagonal SBA-15 mesoporous silica was studied for BPA removal from aqueous phase, and compared with conventional powdered activated carbon (PAC). Characterization of CMK-3 by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption indicated that prepared CMK-3 had an ordered mesoporous structure with a high specific surface area of 920 m2/g and a pore-size of about 4.9 nm. The adsorption of BPA on CMK-3 followed a pseudo second-order kinetic model. The kinetic constant was 0.00049 g/(mg x min), much higher than the adsorption of BPA on PAC. The adsorption isotherm fitted slightly better with the Freundlich model than the Langmuir model, and adsorption capacity decreased as temperature increased from 10 to 40 degrees C. No significant influence of pH on adsorption was observed at pH 3 to 9; however, adsorption capacity decreased dramatically from pH 9 to 13. PMID:21516989

  14. Ethylbenzene Removal by Carbon Nanotubes from Aqueous Solution

    PubMed Central

    Bina, Bijan; Pourzamani, Hamidreza; Rashidi, Alimorad; Amin, Mohammad Mehdi

    2012-01-01

    The removal of ethylbenzene (E) from aqueous solution by multiwalled, single-walled, and hybrid carbon nanotubes (MWCNTs, SWCNTs, and HCNTs) was evaluated for a nanomaterial dose of 1 g/L, concentration of 10–100 mg/L, and pH 7. The equilibrium amount removed by SWCNTs (E: 9.98 mg/g) was higher than by MWCNTs and HCNTs. Ethylbenzene has a higher adsorption tendency on CNTs, so that more than 98% of it adsorbed in first 14 min, which is related to the low water solubility and the high molecular weight. The SWCNTs performed better for ethylbenzene sorption than the HCNTs and MWCNTs. Isotherms study indicates that the BET isotherm expression provides the best fit for ethylbenzene sorption by SWCNTs. Carbon nanotubes, specially SWCNTs, are efficient and rapid adsorbents for ethylbenzene which possess good potential applications to maintain high-quality water. Therefore, it could be used for cleaning up environmental pollution to prevent ethylbenzene borne diseases. PMID:22187576

  15. Nitrate removal performance of Diaphorobacter nitroreducens using biodegradable plastics as the source of reducing power

    NASA Astrophysics Data System (ADS)

    Khan, S. T.; Nagao, Y.; Hiraishi, A.

    2015-02-01

    Strain NA10BT and other two strains of the denitrifying betaproteobacterium Diaphorobacter nitroreducens were studied for the performance of solid-phase denitrification (SPD) using poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and some other biodegradable plastics as the source of reducing power in wastewater treatment. Sequencing-batch SPD reactors with these organisms and PHBV granules or flakes as the substrate exhibited good nitrate removal performance. Vial tests using cultures from these parent reactors showed higher nitrate removal rates with PHBV granules (ca. 20 mg-NO3-- N g-1 [dry wt cells] h-1) than with PHBV pellets and flakes. In continuous-flow SPD reactors using strain NA10BT and PHBV flakes, nitrate was not detected even at a loading rate of 21 mg-NO3-- N L-1 h-1. This corresponded to a nitrate removal rate of 47 mg-NO3-- N g-1 (dry wt cells) h-1. In the continuous-flow reactor, the transcription level of the phaZ gene, coding for PHB depolymerase, decreased with time, while that of the nosZ gene, involved in denitrificaiton, was relatively constant. These results suggest that the bioavailability of soluble metabolites as electron donor and carbon sources increases with time in the continuous-flow SPD process, thereby having much higher nitrate removal rates than the process with fresh PHBV as the substrate.

  16. Effect of carbon source type on intracellular stored polymers during endogenous denitritation (ED) treating landfill leachate.

    PubMed

    Miao, Lei; Wang, Shuying; Li, Baikun; Cao, Tianhao; Zhang, Fangzhai; Wang, Zhong; Peng, Yongzhen

    2016-09-01

    Glycogen accumulating organisms (GAOs) capable of storing organic compounds as polyhydroxyalkanoate (PHA) have been used for endogenous denitritation (ED), but the effect of carbon sources type on nitrogen removal performance of GAOs treating landfill leachate is unclear. In this study, a successful ED system treating landfill leachate (COD/NH4(+)-N (C/N): 4) without external carbon source addition was applied. The mature leachate with C/N of 1 was used as the feeding base solution, with acetate, propionate, and glucose examined as the carbon sources, and their effects on yields and compositions of PHA produced by GAOs were determined and associated with nitrogen removal performance. In the case of sole carbon source, acetate was much easier to be stored than propionate and glucose, which led to a higher nitrogen removal efficiency. Glucose had the lowest amount of PHA storage and led to the lowest performance. In the case of composite carbon sources (two scenarios: acetate + propionate; acetate + propionate + glucose), GAOs stored sufficient PHA and exhibited similar nitrogen removal efficiencies. Moreover, type of carbon source influenced the compositions of PHA. The polyhydroxybutyrate (PHB) fraction in PHA was far more than polyhydroxyvalerate (PHV) in all tests. PHV was synthesized only when acetate existed in carbon source. The microbial diversity analysis revealed that Proteobacteria was the most abundant phylum. Among the 108 genera detected in this ED system, the genera responsible for denitritation were Thauera, Paracoccus, Ottowia and Comamonadaceae_unclassified, accounting for 46.21% of total bacteria. Especially, Paracoccus and Comamonadaceae_unclassified transformed the carbon source into PHA for denitritation, and carried out endogenous denitritation. PMID:27232984

  17. Methods of Boron-carbon Deposited Film Removal

    NASA Astrophysics Data System (ADS)

    Airapetov, A.; Terentiev, V.; Voituk, A.; Zakharov, A.

    Boron carbide was proposed as a material for in-situ renewable protecting coating for tungsten tiles of the ITER divertor. It is necessary to develop a method of gasification of boron-carbon film which deposits during B4C sputtering. In this paper the results of the first stage investigation of gasification methods of boron-carbon films are presented. Two gasification methods of films are investigated: interaction with the ozone-oxygen mixture and irradiation in plasma with the working gas composed of oxygen, ethanol, and, in some cases, helium. The gasification rate in the ozone-oxygen mixture at 250 °C for B/C films with different B/C ratio and carbon fiber composite (CFC), was measured. For B/C films the gasification rate decreased with increasing B/C ratio (from 45 nm/h at B/C=0.7 to 4 nm/h at B/C=2.1; for CFC - 15 μm/h). Films gasification rates were measured under ion irradiation from ethanol-oxygen-helium plasma at different temperatures, with different ion energies and different gas mixtures. The maximum obtained removal rate was near 230 nm/h in case of ethanol-oxygen plasma and at 150°C of the sample temperature.

  18. Removal of Zinc Form Carbonic Anhydrase: A Kinetics Experiment for Upper-Level Chemistry Laboratories

    ERIC Educational Resources Information Center

    Williams, Kathryn R.; Adhyaru, Bhavin

    2004-01-01

    An experiment on kinetics of deactivation of carbonic anhydrase by removal of zinc is demonstrated. Carbonic anhydrase, the enzyme that catalyzes the interconversion of carbon dioxide and bicarbonate, requires on Zn(II) ion in its active site, and removal of the zinc cofactor by complexion to another ligand leaves the apoenzyme, which is totally…

  19. Systemic effects of geoengineering by terrestrial carbon dioxide removal on carbon related planetary boundaries

    NASA Astrophysics Data System (ADS)

    Heck, Vera; Donges, Jonathan; Lucht, Wolfgang

    2015-04-01

    The planetary boundaries framework as proposed by Rockström et al. (2009) provides guidelines for ecological boundaries, the transgression of which is likely to result in a shift of Earth system functioning away from the relatively stable Holocene state. As the climate change boundary is already close to be transgressed, several geoengineering (GE) methods are discussed, aiming at a reduction of atmospheric carbon concentrations to control the Earth's energy balance. One of the proposed GE methods is carbon extraction from the atmosphere via biological carbon sequestration. In case mitigation efforts fail to substantially reduce greenhouse gas emissions, this form of GE could act as potential measure to reduce atmospheric carbon dioxide concentrations. We here study the possible influences of human interactions in the Earth system on carbon related planetary boundaries in the form of geoengineering (terrestrial carbon dioxide removal). We use a conceptual model specifically designed to investigate fundamental carbon feedbacks between land, ocean and atmosphere (Anderies et al., 2013) and modify it to include an additional geoengineering component. With that we analyze the existence and stability of a safe operating space for humanity, which is here conceptualized in three of the 9 proposed dimensions, namely climate change, ocean acidification and land-use. References: J. M. Anderies et al., The topology of non-linear global carbon dynamics: from tipping points to planetary boundaries. Environ. Res. Lett., 8(4):044048 (2013) J. Rockström et al., A safe operating space for humanity. Nature 461 (7263), 472-475 (2009)

  20. Ecological Limits to Terrestrial Carbon Dioxide Removal Strategies

    NASA Astrophysics Data System (ADS)

    Smith, L. J.; Torn, M. S.; Jones, A. D.

    2011-12-01

    Carbon dioxide removal from the atmosphere through terrestrial carbon sequestration and bioenergy (biological CDR) is a proposed climate change mitigation strategy. Biological CDR increases the carbon storage capacity of soils and biomass through changes in land cover and use, including reforestation, afforestation, conversion of land to agriculture for biofuels, conversion of degraded land to grassland, and alternative management practices such as conservation tillage. While biological CDR may play a valuable role in future climate change mitigation, many of its proponents fail to account for the full range of biological, biophysical, hydrologic, and economic complexities associated with proposed land use changes. In this analysis, we identify and discuss a set of ecological limits and impacts associated with terrestrial CDR. The capacity of biofuels, soils, and other living biomass to sequester carbon may be constrained by nutrient and water availability, soil dynamics, and local climate effects, all of which can change spatially and temporally in unpredictable ways. Even if CDR is effective at sequestering CO2, its associated land use and land cover changes may negatively impact ecological resources by compromising water quality and availability, degrading soils, reducing biodiversity, displacing agriculture, and altering local climate through albedo and evapotranspiration changes. Measures taken to overcome ecological limitations, such as fertilizer addition and irrigation, may exacerbate these impacts even further. The ecological considerations and quantitative analyses that we present highlight uncertainties introduced by ecological complexity, disagreements between models, perverse economic incentives, and changing environmental factors. We do not reject CDR as a potentially valuable strategy for climate change mitigation; ecosystem protection, restoration, and improved management practices could enhance soil fertility and protect biodiversity while reducing

  1. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    PubMed Central

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-01-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

  2. Removal of Uranium From Aqueous Solution by Carbon Nanotubes.

    PubMed

    Yu, Jing; Wang, Jianlong

    2016-10-01

    The adsorption of uranium onto carbon nanotubes (CNTs) was investigated. The effect of solution pH, contact time, initial uranium concentration, and temperature on the adsorption capacity of uranium was determined. CNTs were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD), Raman spectra, and the Fourier infrared spectra (FTIR). The diameters of the CNTs varied from 10 to 50 nm in diameter and 1 ~ 2 μm in length. FTIR spectra analysis indicated that carboxyl groups were involved in adsorption of U(VI) by CNTs. The experimental results showed that U(VI) adsorption onto CNTs reached equilibrium within 10 min, and the removal efficiency was 95% at pH = 5. The adsorption kinetics of U(VI) could be described by a pseudo first-order kinetic model. The adsorption isotherm conformed to the Slips model. The adsorption process was spontaneous and endothermic. PMID:27575349

  3. Plasma Treatment to Remove Carbon from Indium UV Filters

    NASA Technical Reports Server (NTRS)

    Greer, Harold F.; Nikzad, Shouleh; Beasley, Matthew; Gantner, Brennan

    2012-01-01

    The sounding rocket experiment FIRE (Far-ultraviolet Imaging Rocket Experiment) will improve the science community fs ability to image a spectral region hitherto unexplored astronomically. The imaging band of FIRE (.900 to 1,100 Angstroms) will help fill the current wavelength imaging observation hole existing from approximately equal to 620 Angstroms to the GALEX band near 1,350 Angstroms. FIRE is a single-optic prime focus telescope with a 1.75-m focal length. The bandpass of 900 to 1100 Angstroms is set by a combination of the mirror coating, the indium filter in front of the detector, and the salt coating on the front of the detector fs microchannel plates. Critical to this is the indium filter that must reduce the flux from Lymanalpha at 1,216 Angstroms by a minimum factor of 10(exp -4). The cost of this Lyman-alpha removal is that the filter is not fully transparent at the desired wavelengths of 900 to 1,100 Angstroms. Recently, in a project to improve the performance of optical and solar blind detectors, JPL developed a plasma process capable of removing carbon contamination from indium metal. In this work, a low-power, low-temperature hydrogen plasma reacts with the carbon contaminants in the indium to form methane, but leaves the indium metal surface undisturbed. This process was recently tested in a proof-of-concept experiment with a filter provided by the University of Colorado. This initial test on a test filter showed improvement in transmission from 7 to 9 percent near 900 with no process optimization applied. Further improvements in this performance were readily achieved to bring the total transmission to 12% with optimization to JPL's existing process.

  4. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds.

    PubMed

    Warneke, Sören; Schipper, Louis A; Matiasek, Michael G; Scow, Kate M; Cameron, Stewart; Bruesewitz, Denise A; McDonald, Ian R

    2011-11-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate (NO(3)(-)) from point source discharges into non-reactive dinitrogen (N(2)) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO(3)(-) removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m(3)) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO(3)(-) enriched water (14.38 mg N L(-1) and 17.15 mg N L(-1)). After 2.5 years of incubation measurements were made of NO(3)(-)-N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO(3)(-), nitrite and ammonia), copy number of nitrite reductase (nirS and nirK) and nitrous oxide reductase (nosZ) genes, and greenhouse gas production (dissolved nitrous oxide (N(2)O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO(3)(-)-N removal. Nitrate-N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m(-3) d(-1) (maize cobs), and were predominantly limited by C availability and temperature (Q(10) = 1.2) when NO(3)(-)-N outlet concentrations remained above 1 mg L(-1). The NO(3)(-)-N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N(2)O emission in

  5. Removal of Selenium and Nitrate in Groundwater Using Organic Carbon-Based Reactive Mixtures

    NASA Astrophysics Data System (ADS)

    An, Hyeonsil; Jeen, Sung-Wook

    2016-04-01

    Treatment of selenium and nitrate in groundwater was evaluated through column experiments. Four columns consisting of reactive mixtures, either organic carbon-limestone (OC-LS) or organic carbon-zero valent iron (OC-ZVI), were used to determine the removal efficiency of selenium with different concentrations of nitrate. The source waters were collected from a mine site in Korea or were prepared artificially based on the mine drainage water or deionized water, followed by spiking of elevated concentrations of Se (40 mg/L) and nitrate (100 or 10 mg/L as NO3-N). The results for the aqueous chemistry showed that selenium and nitrate were effectively removed both in the mine drainage water and deionized water-based artificial input solution. However, the removal of selenium was delayed when selenium and nitrate coexisted in the OC-LS columns. The removal of selenium was not significant when the influent nitrate concentration was 100 mg/L as NO3-N, while most of nitrate was gradually removed within the columns. In contrast, 94% of selenium was removed when the influent nitrate concentration was reduced to 10 mg/L as NO3-N. In the OC-ZVI column, selenium and nitrate was removed almost simultaneously and completely even with the high nitrate concentration; however, a high concentration of ammonia was produced as a by-product of abiotic reaction between ZVI and nitrate. The elemental analysis for the solid samples after the termination of the experiments showed that selenium was accumulated in the reactive materials where removal of aqueous-phase selenium mostly occurred. The X-ray absorption near-edge structure (XANES) study indicated that selenium existed in the forms of SeS2 and Se(0) in the OC-LS column, while selenium was present in the forms of FeSe, SeS2 and absorbed Se(IV) in the OC-ZVI column. This study shows that OC-based reactive mixtures have an ability to remove selenium and nitrate in groundwater. However, the removal of selenium was influenced by the high

  6. Testing a Regenerative Carbon Dioxide and Moisture Removal Technology

    NASA Technical Reports Server (NTRS)

    Barta, Daniel J.; Button, Amy; Sweterlitsch, Jeffrey J.; Curley, Suzanne

    2010-01-01

    The National Aeronautics and Space Administration supported the development of a new vacuum-desorbed regenerative carbon dioxide and humidity control technology for use in short duration human spacecraft. The technology was baselined for use in the Orion Crew Exploration Vehicle s Environmental Control and Life Support System (ECLSS). Termed the Carbon Dioxide And Moisture Removal Amine Swing-bed (CAMRAS), the unit was developed by Hamilton Sundstrand and has undergone extensive testing at Johnson Space Center. The tests were performed to evaluate performance characteristics under range of operating conditions and human loads expected in future spacecraft applications, as part of maturation to increase its readiness for flight. Early tests, conducted at nominal atmospheric pressure, used human metabolic simulators to generate loads, with later tests making us of human test subjects. During these tests many different test cases were performed, involving from 1 to 6 test subjects, with different activity profiles (sleep, nominal and exercise). These tests were conducted within the airlock portion of a human rated test chamber sized to simulate the Orion cabin free air volume. More recently, a test was completed that integrated the CAMRAS with a simulated suit loop using prototype umbilicals and was conducted at reduced atmospheric pressure and elevated oxygen levels. This paper will describe the facilities and procedures used to conduct these and future tests, and provide a summary of findings.

  7. Rhodamine B removal with activated carbons obtained from lignocellulosic waste.

    PubMed

    da Silva Lacerda, Viviane; López-Sotelo, Juan B; Correa-Guimarães, Adriana; Hernández-Navarro, Salvador; Sánchez-Báscones, Mercedes; Navas-Gracia, Luis M; Martín-Ramos, Pablo; Martín-Gil, Jesús

    2015-05-15

    By-products from the wax production process from carnauba palm (leaves), from the extraction of oil from macauba seeds (endocarp) and from pine nut production (shell) have been assessed for activated carbon production, using H3PO4 or CaCl2 for their chemical activation. The resulting activated charcoals have been thoroughly characterized by elemental and thermal analysis, X-ray diffraction, infrared spectroscopy, electron scanning microscopy and N2 adsorption behavior. Subsequently, their adsorption capacity for the removal of rhodamine B (RhB) from aqueous solutions has been evaluated by studying different parameters: contact time, pH, adsorbent dose, initial dye concentration and solution temperature. The adsorption of RhB followed Freundlich's model in all cases. Kinetic studies indicate that the pseudo-second order model can be used for describing the dynamics of the adsorption process. Thermodynamic parameters have also been evaluated, indicating its endothermic and spontaneous nature. Finally, a preliminary analysis of the impact of cellulose content in the carbon precursor materials has been conducted, by using a mixture of native cellulose with one of the lignocellulosic materials. PMID:25770964

  8. Testing a Regenerative Carbon Dioxide and Moisture Removal Technology

    NASA Astrophysics Data System (ADS)

    Barta, Daniel J.; Button, Amy; Sweterlitsch, Jeffrey; Curley, Suzanne

    The National Aeronautics and Space Administration supported the development of a new vacuum-desorbed regenerative carbon dioxide and humidity control technology for use in short duration human spacecraft. The technology was baselined for use in the Orion Crew Exploration Vehicle's Environmental Control and Life Support System (ECLSS). Termed the Carbon Diox-ide And Moisture Removal Amine Swing-bed (CAMRAS), the unit was developed by Hamilton Sundstrand and has undergone extensive testing at Johnson Space Center. The tests were per-formed to evaluate performance characteristics under range of operating conditions and human loads expected in future spacecraft applications, as part of maturation to increase its readiness for flight. Early tests, conducted at nominal atmospheric pressure, used human metabolic sim-ulators to generate loads, with later tests making us of human test subjects. During these tests many different test cases were performed, involving from 1 to 6 test subjects, with different activity profiles (sleep, nominal and exercise). These tests were conducted within the airlock portion of a human rated test chamber sized to simulate the Orion cabin free air volume. More recently, a test was completed that integrated the CAMRAS with a simulated suit loop using prototype umbilicals and was conducted at reduced atmospheric pressure and elevated oxygen levels. This paper will describe the facilities and procedures used to conduct these and future tests, and provide a summary of findings.

  9. Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Ruiz, B.; Cabrita, I.; Mestre, A. S.; Parra, J. B.; Pires, J.; Carvalho, A. P.; Ania, C. O.

    2010-06-01

    The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.

  10. Comparing a silver-impregnated activated carbon with an unmodified activated carbon for disinfection by-product minimisation and precursor removal.

    PubMed

    Watson, Kalinda; Farré, Maria José; Knight, Nicole

    2016-01-15

    During disinfection, bromide, iodide and natural organic matter (NOM) in source waters can lead to the formation of brominated and/or iodinated disinfection by-products (DBPs), which are often more toxic than their chlorinated analogues. The objective of this study was to compare the efficiency of a silver-impregnated activated carbon (SIAC) with the equivalent unimpregnated granular activated carbon (GAC) for the removal of bromide, iodide and NOM from a matrix of synthetic waters with variable NOM, halide, and alkalinity concentrations, and to investigate the impact on DBP formation. An enhanced coagulation (EC) pre-treatment was employed prior to sample exposure to either carbon adsorbent. Excellent halide removals were observed by the SIAC treatment across the sample matrix, with iodide concentrations consistently reduced to below the method reporting limit (<2 μg/L) from as high as 25 μg/L, and 95±4% removal of bromide achieved. Bromide removal by unimpregnated GAC was poor, however iodide removal was comparable to that achieved by SIAC. The combination of EC with SIAC treatment removed 77±8% of the dissolved organic carbon (DOC) present, across the sample matrix, which was similar to removals by EC/GAC (67±14%). Combined EC/SIAC treatment reduced both total trihalomethanes (tTHMs) and total dihaloacetonitriles (tDHANs) formation by 97±3%, while also achieving a greater than 74% removal of two chloropropanones and a 92±8% decrease in chloral hydrate (CH), compared to untreated samples, regardless of the sample's starting water quality (bromide, alkalinity and NOM concentration). Combined EC/GAC treatment led to similar DBP removals to EC/SIAC for the fully chlorinated DBPs, however, brominated DBPs were less efficiently removed, or experienced concentration increases. PMID:26546763

  11. Direct comparison of ozonation and adsorption onto powdered activated carbon for micropollutant removal in advanced wastewater treatment.

    PubMed

    Altmann, Johannes; Ruhl, Aki Sebastian; Zietzschmann, Frederik; Jekel, Martin

    2014-05-15

    Organic micropollutants (OMPs) may occur ubiquitously in the aquatic environment. In order to protect the ecosystem and drinking water sources from potentially toxic effects, discharges of an increasing number of OMPs are being regulated. OMP removal from wastewater treatment plant (WWTP) effluents as a point source is a preferred option with removal by adsorption onto powdered activated carbon (PAC) and OMP transformation to presumably harmless compounds by ozonation as the most promising techniques. In this study, effluents of four WWTPs were treated with PAC and ozone in bench-scale experiments to compare the removal efficiencies of seven relevant OMPs. Concentrations of carbamazepine and diclofenac were reduced by more than 90% with 20 mg/L PAC or 5-7 mg/L ozone (0.5 mg O3 per mg dissolved organic carbon (DOC)). Comparing typical doses for practical applications ozonation proved to be more efficient for abatement of sulfamethoxazole, while removal of benzotriazole and iomeprol was comparatively more efficient with activated carbon. While well known for ozonation, DOC-normalized doses were also applied to PAC and correlated better to relative OMP removal than volume proportional PAC addition. Furthermore, OMP removal efficiencies corresponded well with the reduction of ultraviolet light absorption at 254 nm for both treatment options. PMID:24607314

  12. Double-walled carbon nanotubes synthesized using carbon black as the dot carbon source

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Gang; Li, Feng; Ren, Wen-Cai; Cong, Hongtao; Liu, Chang; Qing Lu, Gao; Cheng, Hui-Ming

    2006-07-01

    Double-walled carbon nanotubes (DWNTs) were synthesized used carbon black as the dot carbon source by a semi-continuous hydrogen arc discharge process. High-resolution transmission electron microscopy (HRTEM) observations revealed that most of the tubes were DWNTs with outer and inner diameters in the range of 2.67-4 nm and 1.96-3.21 nm, respectively. Most of the DWNTs were in a bundle form of about 10-30 nm in diameter with high purity (about 70%) from thermal gravimetric analysis (TGA), resonant laser Raman spectroscopy, scanning electron microscopy (SEM) and TEM characterizations. It was found that carbon black as the dot carbon source could be easy controlled to synthesize one type of nanotube. A simple process combining oxidation and acid treatment to purify the DWNT bundles was used without damaging the bundles. The structure of carbon black, as the key element for influencing purity, bundle formation and purification of DWNTs, is discussed.

  13. REMOVAL OF ORGANIC POLLUTANTS FROM SUBCRITICAL WATER WITH ACTIVATED CARBON

    SciTech Connect

    Steven B. Hawthorne; Arnaud J. Lagadec

    1999-08-01

    The Energy & Environmental Research Center (EERC) has demonstrated that controlling the temperature (and to a lesser extent, the pressure) of water can dramatically change its ability to extract organics and inorganics from matrices ranging from soils and sediments to waste sludges and coal. The dielectric constant of water can be changed from about 80 (a very polar solvent) to <5 (similar to a nonpolar organic solvent) by controlling the temperature (from ambient to about 400 C) and pressure (from about 5 to 350 bar). The EERC has shown that hazardous organic pollutants such as pesticides, PACS (polycyclic aromatic hydrocarbons), and PCBs (polychlorinated biphenyls) can be completely removed from soils, sludges, and sediments at temperatures (250 C) and pressures (<50 atm) that are much milder than typically used for supercritical water processes (temperature >374 C, pressure >221 atm). In addition, the process has been demonstrated to be particularly effective for samples containing very high levels of contaminants (e.g., part per thousand). Current projects include demonstrating the subcritical water remediation process at the pilot scale using an 8-liter system constructed under separate funding during 1997. To date, subcritical water has been shown to be an effective extraction fluid for removing a variety of organic pollutants from soils and sludges contaminated with fossil fuel products and waste products, including PACS from soil (e.g., town gas sites), refining catalysts, and petroleum tank bottom sludges; PCBs from soil and sediments; toxic gasoline components (e.g., benzene) from soil and waste sludge; and phenols from petroleum refinery sludges. The obvious need to clean the wastewater from subcritical water processes led to preliminary experiments with activated carbon placed in line after the extractor. Initial experiments were performed before and after cooling the extractant water (e.g., with water at 200 C and with water cooled to 25 C

  14. Removal of microcystin-LR from spiked water using either activated carbon or anthracite as filter material.

    PubMed

    Drogui, Patrick; Daghrir, Rimeh; Simard, Marie-Christine; Sauvageau, Christine; Blais, Jean François

    2012-01-01

    The occurrence of cyanobacterial toxins (blue-green algae) in drinking water sources is a big concern for human health. Removal of microcystin-LR (MC-LR) from drinking water was evaluated at the laboratory pilot scale using either granular activated carbon (GAC) or powdered activated carbon (PAC) and compared with the treatment using anthracite as filter material. Virgin GAC was more effective at removing MC-LR (initial concentration ranging from 9 to 47 microg L(-1)) to reach the World Health Organization recommended level (1.0 microg L(-1)). When the GAC filter was colonized by bacteria, the filter became less effective at removing MC-LR owing to competitive reactions occurring between protein adsorption (released by bacteria) and MC-LR adsorption. Using PAC, the concentration of MC-LR decreased from 22 to 3 microg L(-1) (removal of 86% of MC-LR) by the addition of 100 mg PAC L(-1). PMID:22629609

  15. New Potential Sources for Black Onaping Carbon

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, L.; Schultz, P. H.; Wolbach, W. S.

    1997-01-01

    One intriguing and important issue of the Sudbury Structure concerns the source of the relatively large amount of C in the Onaping Formation Black member. This dilemma was recently addressed, and the conclusion was reached that an impactor could not have delivered all of the requisite C. Becker et al. have suggested that much of the C came from the impactor and reported the presence of interstellar He "caged" inside some fullerenes that may have survived the impact. So, conceivably, the C inventory in the Sudbury Structure comes from both target and impactor materials, although the known target rocks have little C. We discuss here the possibility of two terrestrial sources for at least some of the C: (1) impact evaporation/dissociation of C from carbonate target rocks and (2) the presence of heretofore-unrecognized C-rich (up to 26 wt%) siliceous "shale," fragments, which are found in the upper, reworked Black member. Experimental: Hypervelocity impact of a 0.635-diameter Al projectile into dolomite at 5.03 km/s (performed at the Ames Research Center vertical gun range) produced a thin, black layer (= 0.05 mm thick) that partially lined the crater and coated impactor remnants. Scanning electronic microscope (SEM) imagery shows this layer to be spongelike on a submicron scale and Auger spectroscopic analyses yield: 33% C, 22% Mg, 19% 0, and 9% Al (from the projectile). Elemental mapping shows that all of the available 0 is combined with Ca and Mg, Al is not oxidized, and C is in elemental form. Dissociation efficiency of C from CO2 is estimated to be <10% of crater volume. Raman spectroscopy indicates that the C is highly disorganized graphite. Another impact experiment [4] also produced highly disordered graphite from a limestone target (reducing collector), in addition to small amounts of diamond/lonsdaleite/chaoite (oxidizing collector). These experiments confirm the reduction of C from carbonates in impact vapor plumes. Observational: SEM observations and

  16. Treatment of hydroponic wastewater by denitrification filters using plant prunings as the organic carbon source.

    PubMed

    Park, J B K; Craggs, R J; Sukias, J P S

    2008-05-01

    This study investigated the feasibility of using pre-treated plant liquors as organic carbon sources for the treatment of hydroponic wastewater containing high nitrate-N (>300 mg N/L). The waste plant material was pre-treated to extract organic carbon-rich liquors. When this plant liquor was used as an organic carbon source in denitrification filters at the organic carbon:nitrogen dose rate of 3C:N, nitrate removal efficiencies were >95% and final effluent nitrate concentrations were consistently <20mg N/L. However, at this dose rate, relatively high concentrations (>140 mg/L) of organic carbon (fBOD5) remained in the final effluents. Therefore, a 'compromise' organic carbon:nitrogen dose rate (2C:N) was trialled, at which nitrate removal efficiencies were maintained at >85%, final effluent nitrate concentrations were consistently below 45 mg N/L, and effluent fBOD5 concentrations were <25mg/L. This study has demonstrated that waste plant material is a suitable carbon source for the removal of nitrate from hydroponic wastewater in a denitrification filter. PMID:17714940

  17. Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

    PubMed

    Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

    2015-11-25

    Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II). PMID:26540557

  18. Nitrogen removal from coal gasification wastewater by activated carbon technologies combined with short-cut nitrogen removal process.

    PubMed

    Zhao, Qian; Han, Hongjun; Hou, Baolin; Zhuang, Haifeng; Jia, Shengyong; Fang, Fang

    2014-11-01

    A system combining granular activated carbon and powdered activated carbon technologies along with shortcut biological nitrogen removal (GAC-PACT-SBNR) was developed to enhance total nitrogen (TN) removal for anaerobically treated coal gasification wastewater with less need for external carbon resources. The TN removal efficiency in SBNR was significantly improved by introducing the effluent from the GAC process into SBNR during the anoxic stage, with removal percentage increasing from 43.8%-49.6% to 68.8%-75.8%. However, the TN removal rate decreased with the progressive deterioration of GAC adsorption. After adding activated sludge to the GAC compartment, the granular carbon had a longer service-life and the demand for external carbon resources became lower. Eventually, the TN removal rate in SBNR was almost constant at approx. 43.3%, as compared to approx. 20.0% before seeding with sludge. In addition, the production of some alkalinity during the denitrification resulted in a net savings in alkalinity requirements for the nitrification reaction and refractory chemical oxygen demand (COD) degradation by autotrophic bacteria in SBNR under oxic conditions. PACT showed excellent resilience to increasing organic loadings. The microbial community analysis revealed that the PACT had a greater variety of bacterial taxons and the dominant species associated with the three compartments were in good agreement with the removal of typical pollutants. The study demonstrated that pre-adsorption by the GAC-sludge process could be a technically and economically feasible method to enhance TN removal in coal gasification wastewater (CGW). PMID:25458677

  19. Made-to-order metal-organic frameworks for trace carbon dioxide removal and air capture

    PubMed Central

    Shekhah, Osama; Belmabkhout, Youssef; Chen, Zhijie; Guillerm, Vincent; Cairns, Amy; Adil, Karim; Eddaoudi, Mohamed

    2014-01-01

    Direct air capture is regarded as a plausible alternate approach that, if economically practical, can mitigate the increasing carbon dioxide emissions associated with two of the main carbon polluting sources, namely stationary power plants and transportation. Here we show that metal-organic framework crystal chemistry permits the construction of an isostructural metal-organic framework (SIFSIX-3-Cu) based on pyrazine/copper(II) two-dimensional periodic 44 square grids pillared by silicon hexafluoride anions and thus allows further contraction of the pore system to 3.5 versus 3.84 Å for the parent zinc(II) derivative. This enhances the adsorption energetics and subsequently displays carbon dioxide uptake and selectivity at very low partial pressures relevant to air capture and trace carbon dioxide removal. The resultant SIFSIX-3-Cu exhibits uniformly distributed adsorption energetics and offers enhanced carbon dioxide physical adsorption properties, uptake and selectivity in highly diluted gas streams, a performance, to the best of our knowledge, unachievable with other classes of porous materials. PMID:24964404

  20. Made-to-order metal-organic frameworks for trace carbon dioxide removal and air capture

    NASA Astrophysics Data System (ADS)

    Shekhah, Osama; Belmabkhout, Youssef; Chen, Zhijie; Guillerm, Vincent; Cairns, Amy; Adil, Karim; Eddaoudi, Mohamed

    2014-06-01

    Direct air capture is regarded as a plausible alternate approach that, if economically practical, can mitigate the increasing carbon dioxide emissions associated with two of the main carbon polluting sources, namely stationary power plants and transportation. Here we show that metal-organic framework crystal chemistry permits the construction of an isostructural metal-organic framework (SIFSIX-3-Cu) based on pyrazine/copper(II) two-dimensional periodic 44 square grids pillared by silicon hexafluoride anions and thus allows further contraction of the pore system to 3.5 versus 3.84 Å for the parent zinc(II) derivative. This enhances the adsorption energetics and subsequently displays carbon dioxide uptake and selectivity at very low partial pressures relevant to air capture and trace carbon dioxide removal. The resultant SIFSIX-3-Cu exhibits uniformly distributed adsorption energetics and offers enhanced carbon dioxide physical adsorption properties, uptake and selectivity in highly diluted gas streams, a performance, to the best of our knowledge, unachievable with other classes of porous materials.

  1. Surface modification of coconut shell based activated carbon for the improvement of hydrophobic VOC removal.

    PubMed

    Li, Lin; Liu, Suqin; Liu, Junxin

    2011-08-30

    In this study, coconut shell based carbons were chemically treated by ammonia, sodium hydroxide, nitric acid, sulphuric acid, and phosphoric acid to determine suitable modification for improving adsorption ability of hydrophobic volatile organic compounds (VOCs) on granular activated carbons (GAC). The saturated adsorption capacities of o-xylene, a hydrophobic volatile organic compound, were measured and adsorption effects of the original and modified activated carbons were compared. Results showed that GAC modified by alkalis had better o-xylene adsorption capacity. Uptake amount was enhanced by 26.5% and reduced by 21.6% after modification by NH(3)H(2)O and H(2)SO(4), respectively. Compared with the original, GAC modified by acid had less adsorption capacity. Both SEM/EDAX and BET were used to identify the structural characteristics of the tested GAC, while IR spectroscopy and Boehm's titration were applied to analysis the surface functional groups. Relationships between physicochemical characteristics of GAC and their adsorption performances demonstrated that o-xylene adsorption capacity was related to surface area, pore volume, and functional groups of the GAC surface. Removing surface oxygen groups, which constitute the source of surface acidity, and reducing hydrophilic carbon surface favors adsorption capacity of hydrophobic VOCs on carbons. The performances of modified GACs were also investigated in the purification of gases containing complex components (o-xylene and steam) in the stream. PMID:21683520

  2. Utilization of carbon nanotubes for the removal of rhodamine B dye from aqueous solutions.

    PubMed

    Kumar, Sandeep; Bhanjana, Gaurav; Jangra, Kavita; Dilbaghi, Neeraj; Umar, Ahmad

    2014-06-01

    Carbon nanotubes (CNTs) are attracting increasing research interest as promising adsorbents for harmful cations, anions, and other organic and inorganic impurities present in natural sources of water. This study examined the feasibility of removing Rhodamine B dye from aqueous solutions using multi walled carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition (CVD) method. The effects of dye concentration, pH and contact time on adsorption of direct dye by CNTs were also evaluated. The study used the Langmuir and Temkin isotherms to describe equilibrium adsorption. Additionally, pseudo second-order model was adopted to evaluate experimental data and thereby elucidate the kinetic adsorption process. The adsorption percentage of dye increased as contact time increased. Conversely, the adsorption percentage of dye decreased as dye concentration increased. The pseudo second-order model best represented adsorption kinetics. The capacity of CNTs to adsorb Rhodamine B was 65-90% at different pH values. PMID:24738392

  3. Development of Carbon Dioxide Removal Systems for Advanced Exploration Systems

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Trinh, Diep; Gostowski, Rudy; King, Eric; Mattox, Emily M.; Watson, David; Thomas, John

    2012-01-01

    "NASA's Advanced Exploration Systems (AES) program is pioneering new approaches for rapidly developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit" (NASA 2012). These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must not only blast out of earth's gravity well as during the Apollo moon missions, but also launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by seeking more robust pelletized sorbents, evaluating structured sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach, which is then implemented in a full-scale integrated atmosphere revitalization test. This paper describes the carbon dioxide (CO2) removal hardware design and sorbent screening and characterization effort in support of the Atmosphere Resource Recovery and Environmental Monitoring (ARREM) project within the AES program. A companion paper discusses development of atmosphere revitalization models and simulations for this project.

  4. Early Implementation of Large Scale Carbon Dioxide Removal Projects through the Cement Industry

    NASA Astrophysics Data System (ADS)

    Zeman, F. S.

    2014-12-01

    The development of large-scale carbon dioxide reduction projects requires high purity CO2and a reactive cation source. A project seeking to provide both of these requirements will likely face cost barriers with current carbon prices. The cement industry is a suitable early implementation site for such projects by virtue of the properties of its exhaust gases and those of waste concrete. Cement plants are the second largest source of industrial CO2 emissions, globally. It is also the second largest commodity after water, has no ready substitute and is literally the foundation of society. Finally, half of the CO2 emissions originate from process reactions rather than fossil fuel combustion resulting in higher flue gas CO2concentrations. These properties, with the co-benefits of oxygen combustion, create a favorable environment for spatially suitable projects. Oxygen combustion involves substituting produced oxygen for air in a combustion reaction. The absence of gaseous N2 necessitates the recirculation of exhaust gases to maintain kiln temperatures, which increase the CO2 concentrations from 28% to 80% or more. Gas exit temperatures are also elevated (>300oC) and can reach higher temperatures if the multi stage pre-heater towers, that recover heat, are re-designed in light of FGR. A ready source of cations can be found in waste concrete, a by-product of construction and demolition activities. These wastes can be processed to remove cations and then reacted with atmospheric CO2 to produce carbonate minerals. While not carbon negative, they represent a demonstration opportunity for binding atmospheric CO2while producing a saleable product (precipitated calcium carbonate). This paper will present experimental results on PCC production from waste concrete along with modeling results for oxygen combustion at cement facilities. The results will be presented with a view to mineral sequestration process design and implementation.

  5. [Effect of PLA/starch slow-release carbon source on biological denitrification].

    PubMed

    Tang, Dan-Qi; Wang, Juan; Zheng, Tian-Long; Liu, Jian-Guo; Wang, Qun-Hui

    2014-06-01

    We used polylactic acid (PLA) and starch to develop a slow-release carbon source and biofilm carrier by blending and fusing techniques for removing nitrate contamination from groundwater, investigated the changes of nitrate, nitrite concentrations and COD in denitrification process supplied by the slow-release carbon source in different mass ratios [PLA/starch (P: S) were 8:2, 7:3, 6:4, 5:5, respectively]. The experimental results demonstrated that the best mass ratio of PLA/starch was 5:5, resulting in a nitrate removal rate of more than 99%. A high denitrification performance was achieved in continuous fixed-bed reactor, the effluent nitrate concentration was below 2 mg x L(-1). These experiments provide scientific basis for the development of environmentally-friendly and controllable slow-release carbon source. PMID:25158501

  6. Controlled epitaxial graphene growth within removable amorphous carbon corrals

    SciTech Connect

    Palmer, James; Hu, Yike; Hankinson, John; Guo, Zelei; Heer, Walt A. de; Kunc, Jan; Berger, Claire

    2014-07-14

    We address the question of control of the silicon carbide (SiC) steps and terraces under epitaxial graphene on SiC and demonstrate amorphous carbon (aC) corrals as an ideal method to pin SiC surface steps. aC is compatible with graphene growth, structurally stable at high temperatures, and can be removed after graphene growth. For this, aC is first evaporated and patterned on SiC, then annealed in the graphene growth furnace. There at temperatures above 1200 °C, mobile SiC steps accumulate at the aC corral that provide effective step flow barriers. Aligned step free regions are thereby formed for subsequent graphene growth at temperatures above 1330 °C. Atomic force microscopy imaging supports the formation of step-free terraces on SiC with the step morphology aligned to the aC corrals. Raman spectroscopy indicates the presence of good graphene sheets on the step-free terraces.

  7. Controlled epitaxial graphene growth within removable amorphous carbon corrals

    NASA Astrophysics Data System (ADS)

    Palmer, James; Kunc, Jan; Hu, Yike; Hankinson, John; Guo, Zelei; Berger, Claire; de Heer, Walt A.

    2014-07-01

    We address the question of control of the silicon carbide (SiC) steps and terraces under epitaxial graphene on SiC and demonstrate amorphous carbon (aC) corrals as an ideal method to pin SiC surface steps. aC is compatible with graphene growth, structurally stable at high temperatures, and can be removed after graphene growth. For this, aC is first evaporated and patterned on SiC, then annealed in the graphene growth furnace. There at temperatures above 1200 °C, mobile SiC steps accumulate at the aC corral that provide effective step flow barriers. Aligned step free regions are thereby formed for subsequent graphene growth at temperatures above 1330 °C. Atomic force microscopy imaging supports the formation of step-free terraces on SiC with the step morphology aligned to the aC corrals. Raman spectroscopy indicates the presence of good graphene sheets on the step-free terraces.

  8. Nitrate removal performance of Diaphorobacter nitroreducens using biodegradable plastics as the source of reducing power

    SciTech Connect

    Khan, S. T.; Nagao, Y.; Hiraishi, A.

    2015-02-27

    Strain NA10B{sup T} and other two strains of the denitrifying betaproteobacterium Diaphorobacter nitroreducens were studied for the performance of solid-phase denitrification (SPD) using poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and some other biodegradable plastics as the source of reducing power in wastewater treatment. Sequencing-batch SPD reactors with these organisms and PHBV granules or flakes as the substrate exhibited good nitrate removal performance. Vial tests using cultures from these parent reactors showed higher nitrate removal rates with PHBV granules (ca. 20 mg-NO{sub 3}{sup −}‐N g{sup −1} [dry wt cells] h{sup −1}) than with PHBV pellets and flakes. In continuous-flow SPD reactors using strain NA10B{sup T} and PHBV flakes, nitrate was not detected even at a loading rate of 21 mg-NO{sub 3}{sup −}‐N L{sup −1} h{sup −1}. This corresponded to a nitrate removal rate of 47 mg-NO{sub 3}{sup −}‐N g{sup −1} (dry wt cells) h{sup −1}. In the continuous-flow reactor, the transcription level of the phaZ gene, coding for PHB depolymerase, decreased with time, while that of the nosZ gene, involved in denitrificaiton, was relatively constant. These results suggest that the bioavailability of soluble metabolites as electron donor and carbon sources increases with time in the continuous-flow SPD process, thereby having much higher nitrate removal rates than the process with fresh PHBV as the substrate.

  9. Intensified nitrogen removal in immobilized nitrifier enhanced constructed wetlands with external carbon addition.

    PubMed

    Wang, Wei; Ding, Yi; Wang, Yuhui; Song, Xinshan; Ambrose, Richard F; Ullman, Jeffrey L

    2016-10-01

    Nitrogen removal performance response of twelve constructed wetlands (CWs) to immobilized nitrifier pellets and different influent COD/N ratios (chemical oxygen demand: total nitrogen in influent) were investigated via 7-month experiments. Nitrifier was immobilized on a carrier pellet containing 10% polyvinyl alcohol (PVA), 2.0% sodium alginate (SA) and 2.0% calcium chloride (CaCl2). A batch experiment demonstrated that 73% COD and 85% ammonia nitrogen (NH4-N) were degraded using the pellets with immobilized nitrifier cells. In addition, different carbon source supplement strategies were applied to remove the nitrate (NO3-N) transformed from NH4-N. An increase in COD/N ratio led to increasing reduction in NO3-N. Efficient nitrification and denitrification promoted total nitrogen (TN) removal in immobilized nitrifier biofortified constructed wetlands (INB-CWs). The results suggested that immobilized nitrifier pellets combined with high influent COD/N ratios could effectively improve the nitrogen removal performance in CWs. PMID:27396293

  10. Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source

    NASA Astrophysics Data System (ADS)

    Nauta, Ake L.; Heijmans, Monique M. P. D.; Blok, Daan; Limpens, Juul; Elberling, Bo; Gallagher, Angela; Li, Bingxi; Petrov, Roman E.; Maximov, Trofim C.; van Huissteden, Jacobus; Berendse, Frank

    2015-01-01

    Arctic tundra ecosystems are warming almost twice as fast as the global average. Permafrost thaw and the resulting release of greenhouse gases from decomposing soil organic carbon have the potential to accelerate climate warming. In recent decades, Arctic tundra ecosystems have changed rapidly, including expansion of woody vegetation, in response to changing climate conditions. How such vegetation changes contribute to stabilization or destabilization of the permafrost is unknown. Here we present six years of field observations in a shrub removal experiment at a Siberian tundra site. Removing the shrub part of the vegetation initiated thawing of ice-rich permafrost, resulting in collapse of the originally elevated shrub patches into waterlogged depressions within five years. This thaw pond development shifted the plots from a methane sink into a methane source. The results of our field experiment demonstrate the importance of the vegetation cover for protection of the massive carbon reservoirs stored in the permafrost and illustrate the strong vulnerability of these tundra ecosystems to perturbations. If permafrost thawing can more frequently trigger such local permafrost collapse, methane-emitting wet depressions could become more abundant in the lowland tundra landscape, at the cost of permafrost-stabilizing low shrub vegetation.

  11. Characterization and restoration of performance of {open_quotes}aged{close_quotes} radioiodine removing activated carbons

    SciTech Connect

    Freeman, W.P.

    1997-08-01

    The degradation of radioiodine removal performance for impregnated activated carbons because of ageing is well established. However, the causes for this degradation remain unclear. One theory is that this reduction in performance from the ageing process results from an oxidation of the surface of the carbon. Radioiodine removing activated carbons that failed radioiodine removal tests showed an oxidized surface that had become hydrophilic compared with new carbons. We attempted to restore the performance of these {open_quotes}failed{close_quotes} carbons with a combination of thermal and chemical treatment. The results of these investigations are presented and discussed with the view of extending the life of radioiodine removing activated carbons. 4 refs., 2 tabs.

  12. Simultaneous removal of nitrate and arsenic from drinking water sources utilizing a fixed-bed bioreactor system.

    PubMed

    Upadhyaya, Giridhar; Jackson, Jeff; Clancy, Tara M; Hyun, Sung Pil; Brown, Jess; Hayes, Kim F; Raskin, Lutgarde

    2010-09-01

    A novel bioreactor system, consisting of two biologically active carbon (BAC) reactors in series, was developed for the simultaneous removal of nitrate and arsenic from a synthetic groundwater supplemented with acetic acid. A mixed biofilm microbial community that developed on the BAC was capable of utilizing dissolved oxygen, nitrate, arsenate, and sulfate as the electron acceptors. Nitrate was removed from a concentration of approximately 50 mg/L in the influent to below the detection limit of 0.2 mg/L. Biologically generated sulfides resulted in the precipitation of the iron sulfides mackinawite and greigite, which concomitantly removed arsenic from an influent concentration of approximately 200 ug/L to below 20 ug/L through arsenic sulfide precipitation and surface precipitation on iron sulfides. This study showed for the first time that arsenic and nitrate can be simultaneously removed from drinking water sources utilizing a bioreactor system. PMID:20732708

  13. Effect of Carbon and Energy Source on Bacterial Chromate Reduction

    SciTech Connect

    Smith, William Aaron; Apel, William Arnold; Petersen, J. N.; Peyton, Brent Michael

    2002-07-01

    Studies were conducted to evaluate carbon and energy sources suitable to support hexavalent chromium (Cr(VI)) reduction by a bacterial consortium enriched from dichromate-contaminated aquifer sediments. The consortium was cultured under denitrifying conditions in a minimal, synthetic groundwater medium that was amended with various individual potential carbon and energy sources. The effects of these individual carbon and energy sources on Cr(VI) reduction and growth were measured. The consortium was found to readily reduce Cr(VI) with sucrose, acetate, L-asparagine, hydrogen plus carbon dioxide, ethanol, glycerol, glycolate, propylene glycol, or D-xylose as a carbon and energy source. Minimal Cr(VI) reduction was observed when the consortium was cultured with citrate, 2-ketoglutarate, L-lactate, pyruvate, succinate, or thiosulfate plus carbon dioxide as a carbon and energy source when compared with abiotic controls. The consortium grew on all of the above carbon and energy sources, with the highest cell densities reached using D-xylose and sucrose, demonstrating that the consortium is metabolically diverse and can reduce Cr(VI) using a variety of different carbon and energy sources. The results suggest that the potential exists for the enrichment of Cr(VI)-reducing microbial populations in situ by the addition of a sucrose-containing feedstock such as molasses, which is an economical and readily available carbon and energy source.

  14. New Potential Sources for Black Onaping Carbon

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, L.; Schultz, P. H.; Wolbach, W. S.

    1997-01-01

    One intriguing and important issue of the Sudbury Structure concerns the source of the relatively large amount of C in the Onaping Formation Black member. This dilemma was recently addressed, and the conclusion was reached that an impactor could not have delivered all of the requisite C. Becker et al. have suggested that much of the C came from the impactor and reported the presence of interstellar He "caged" inside some fullerenes that may have survived the impact. So, conceivably, the C inventory in the Sudbury Structure comes from both target and impactor materials, although the known target rocks have little C. We discuss here the possibility of two terrestrial sources for at least some of the C: (1) impact evaporation/dissociation of C from carbonate target rocks and (2) the presence of heretofore-unrecognized C-rich (up to 26 wt%) siliceous "shale," fragments, which are found in the upper, reworked Black member. Experimental: Hypervelocity impact of a 0.635-diameter Al projectile into dolomite at 5.03 km/s (performed at the Ames Research Center vertical gun range) produced a thin, black layer (= 0.05 mm thick) that partially lined the crater and coated impactor remnants. Scanning electronic microscope (SEM) imagery shows this layer to be spongelike on a submicron scale and Auger spectroscopic analyses yield: 33% C, 22% Mg, 19% 0, and 9% Al (from the projectile). Elemental mapping shows that all of the available 0 is combined with Ca and Mg, Al is not oxidized, and C is in elemental form. Dissociation efficiency of C from CO2 is estimated to be <10% of crater volume. Raman spectroscopy indicates that the C is highly disorganized graphite. Another impact experiment [4] also produced highly disordered graphite from a limestone target (reducing collector), in addition to small amounts of diamond/lonsdaleite/chaoite (oxidizing collector). These experiments confirm the reduction of C from carbonates in impact vapor plumes. Observational: SEM observations and

  15. Removal of As(V) using iron oxide impregnated carbon prepared from Tamarind hull.

    PubMed

    Maiti, Abhijit; Agarwal, Vaibhav; De, Sirshendu; Basu, Jayanta K

    2010-08-01

    Iron oxide impregnated tamarind hull carbon (IOITHC) was developed for use as an adsorbent for the removal of As(V) from water. Tamarind hull was used as the source of carbonaceous material, which was first treated with ferric chloride and ammonium hydroxide solutions with successive calcination at 873-974 K in a muffle furnace for 1 h to prepare an arsenic adsorbent. The B.E.T surface area of IOITHC was found to be 304.6 m(2) g(-1) and the average iron content in the adsorbent was found to be 7 wt%. The point of zero charge (pH(zpc)) of IOITHC was found to be 6.9. As(V) and arsenic (as total) adsorption on IOITHC were investigated in batch mode using As(V) spiked distilled water and real contaminated groundwater (CGW). The effects of speed of agitation, adsorbent particle size, temperature, pH of the solution, and concentration of the adsorbate on the adsorption process were investigated. The maximum adsorption capacity of about 1.2 mg g(-1) As(V) was achieved. The removal of As(V) on IOITHC was compared with the untreated tamarind hull carbon as well as with the activated commercial carbon and IOITHC was found to be better adsorbent. Arsenic adsorption from arsenic contaminated groundwater (CGW) on IOITHC in batch mode indicates that 98% removal was achieved for adsorbent loading of 3.0 g L(-1) with initial arsenic concentration of 264 microg L(-1). Desorption study of arsenic from As(V)-loaded IOITHC was performed using aqueous solution in the pH range of 3 to 12. PMID:20563914

  16. A three step approach for removing organic matter from South African water sources and treatment plants

    NASA Astrophysics Data System (ADS)

    Nkambule, T. I.; Krause, R. W. M.; Haarhoff, J.; Mamba, B. B.

    The high variability in the levels and composition of natural organic matter (NOM) in South-African water sources in different regions means that no single treatment process can be prescribed for each water treatment plant operating in the country. In order to remove NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, especially as it may not necessarily be uniform since the composition is dependent on local environmental situation. The primary objective of this study was to characterise the NOM present in South African source waters through an extensive sampling of representative water types across the country and then develop a rapid NOM characterisation protocol. Water samples were thus collected from eight different water treatment plants located throughout the country at different sites of their water treatment trains. Raw water samples, the intermediate samples before filtration and water samples before disinfection were collected at these drinking water treatment plants. The fluorescence excitation-emission matrices (FEEMs), biodegradable dissolved organic carbon (BDOC), ultraviolet (UV) characterisation (200-900 nm) and dissolved organic carbon (DOC) analysis were used to characterise the NOM in the water samples. The FEEM and UV results revealed that the samples were composed mainly of humic substances with a high UV-254 absorbance, while some samples had marine humic substances and non-humic substances. The sample’s DOC results were within the range of 3.25-21.44 mg C/L, which was indicative of the varying nature of the NOM composition in the regions where samples were obtained. The BDOC fraction of the NOM, on the other hand, ranged from 20% to 65%, depending on the geographical location of the sampling site. It is evident from the results obtained that the NOM composition varied per sampling site which would eventually have a bearing on its treatability. The various water treatment

  17. Binderless carbon nanotube/carbon fibre composites for electrochemical micropower sources.

    PubMed

    Bordjiba, Tarik; Mohamedi, Mohamed; Dao, Lê H

    2007-01-24

    Interesting architectures built with electrically conductive substrates of interest for microelectrochemical power sources were obtained by directly growing carbon nanotubes on each microfibre constituting a carbon paper. The carbon nanotubes were fabricated by the chemical vapour deposition technique. Results of electrochemical tests showed high-resolution responses in different chemical media, which indicate good electrical contact between the carbon nanotubes and the carbon paper substrate. These architectures hold great promise for incorporation into microelectrochemical power sources. PMID:19636112

  18. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  19. Diagnostic Evaluation of Carbon Sources in CMAQ

    EPA Science Inventory

    Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed di...

  20. Anaerobic biogranulation using phenol as the sole carbon source

    SciTech Connect

    Tay, J.H.; He, Y.X.; Yan, Y.G.

    2000-04-01

    The granulation process was extensively examined using phenol as sole carbon source in a 2-L laboratory upflow anaerobic sludge blanket (UASB) reactor. The study was conducted mesophilically at 35 C. Anaerobically digested sludge was used as seed after a 14-day activation period with glucose feed. Massive initial granules were developed after 3 months of startup, grew at an accelerated pace for 6 months, then became fully grown. The granulation process can be broken into three phases: acclimation, granulation, and maturation. However, granulation with phenol proceeded more slowly than it did in UASB reactors fed with readily biodegradable carbohydrates studied previously. The granular sludge cultivated had a median diameter of 1.8 mm, phenol-degrading activity of 0.65 g chemical oxygen demand (COD)/g volatile suspended solids (VSS){sm_bullet}d, and a sludge volume index of 14 mL/g. Phenol COD removal efficiency of 86% was achieved when the reactor was operating at an influent phenol concentration of 1,260 mg/L (corresponding to 3,000 mg COD/L), hydraulic retention time of 12 hours, and volumetric loading rate of 6 g COD/L{sm_bullet}d. However, the lower-than-expected phenol COD removal efficiency could be attributed to inhibition by the high influent phenol concentration or loading. The batch test demonstrated that the sludge methanogenic activity was reduced by 52 and 75% at phenol concentrations of 420 and 840 mg/L, respectively.

  1. Treating low carbon/nitrogen (C/N) wastewater in simultaneous nitrification-endogenous denitrification and phosphorous removal (SNDPR) systems by strengthening anaerobic intracellular carbon storage.

    PubMed

    Wang, Xiaoxia; Wang, Shuying; Xue, Tonglai; Li, Baikun; Dai, Xian; Peng, Yongzhen

    2015-06-15

    A novel simultaneous nitrification denitrification and phosphorous removal-sequencing batch reactor (SNDPR-SBR) enriched with PAOs (phosphorus accumulating organisms), DPAOs (denitrifying PAOs), and GAOs (glycogen accumulating organisms) at the ratio of 2:1:1 was developed to achieve the simultaneous nutrient and carbon removal treating domestic wastewater with low carbon/nitrogen ratio (≤3.5). The SNDPR system was operated for 120 days at extended anaerobic stage (3 h) and short aerobic stage at low oxygen concentration (2.5 h) with short sludge retention time (SRT) of 10.9 d and hydraulic retention time (HRT) of 14.6 h. The results showed that at the stable operating stage, the average effluent chemical oxygen demand (COD) and PO4(3-)-P concentrations were 47.2 and 0.2 mg L(-1), respectively, the total nitrogen (TN) removal efficiency was 77.7%, and the SND efficiency reached 49.3%. Extended anaerobic stage strengthened the intracellular carbon (mainly poly-β-hydroxybutyrate, PHB) storage, efficiently utilized the organic substances in wastewater, and provided sufficient carbon sources for denitrification and phosphorus uptake without external carbon addition. Short aerobic stage at low oxygen concentration (dissolved oxygen (DO): 1 ± 0.3 mg L(-1)) achieved a concurrence of nitrification, endogenous denitrification, denitrifying and aerobic phosphorus uptake, and saved about 65% energy consumption for aeration. Microbial community analysis demonstrated that P removal was mainly performed by aerobic PAOs while N removal was mainly carried out by denitrifying GAOs (DGAOs), even though DPAOs were also participated in both N and P removal. PMID:25875928

  2. 10 CFR 35.2404 - Records of surveys after source implant and removal.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of surveys after source implant and removal. 35.2404 Section 35.2404 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2404 Records of surveys after source implant and removal. A licensee shall maintain a record...

  3. 10 CFR 35.2404 - Records of surveys after source implant and removal.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Records of surveys after source implant and removal. 35.2404 Section 35.2404 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2404 Records of surveys after source implant and removal. A licensee shall maintain a record...

  4. 10 CFR 35.2404 - Records of surveys after source implant and removal.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Records of surveys after source implant and removal. 35.2404 Section 35.2404 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2404 Records of surveys after source implant and removal. A licensee shall maintain a record...

  5. 10 CFR 35.2404 - Records of surveys after source implant and removal.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Records of surveys after source implant and removal. 35.2404 Section 35.2404 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2404 Records of surveys after source implant and removal. A licensee shall maintain a record...

  6. 10 CFR 35.2404 - Records of surveys after source implant and removal.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Records of surveys after source implant and removal. 35.2404 Section 35.2404 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2404 Records of surveys after source implant and removal. A licensee shall maintain a record...

  7. Method and apparatus for selective removal of carbon monoxide

    DOEpatents

    Borup, Rodney L.; Skala, Glenn W.; Brundage, Mark A.; LaBarge, William J.

    2000-01-01

    There is provided a method and apparatus for treatment of a hydrogen-rich gas to reduce the carbon monoxide content thereof by reacting the carbon monoxide in the gas with an amount of oxygen sufficient to oxidize at least a portion of the carbon monoxide in the presence of a catalyst in a desired temperature range without substantial reaction of hydrogen. The catalyst is an iridium-based catalyst dispersed on, and supported on, a carrier. In the presence of the catalyst, carbon monoxide in a hydrogen-rich feed gas is selectively oxidized such that a product stream is produced with a very low carbon monoxide content.

  8. Apparatus and method for removing solvent from carbon dioxide in resin recycling system

    DOEpatents

    Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

    2009-01-06

    A two-step resin recycling system and method solvent that produces essentially contaminant-free synthetic resin material. The system and method includes one or more solvent wash vessels to expose resin particles to a solvent, the solvent contacting the resin particles in the one or more solvent wash vessels to substantially remove contaminants on the resin particles. A separator is provided to separate the solvent from the resin particles after removal from the one or more solvent wash vessels. The resin particles are next exposed to carbon dioxide in a closed loop carbon dioxide system. The closed loop system includes a carbon dioxide vessel where the carbon dioxide is exposed to the resin, substantially removing any residual solvent remaining on the resin particles after separation. A separation vessel is also provided to separate the solvent from the solvent laden carbon dioxide. Both the carbon dioxide and the solvent are reused after separation in the separation vessel.

  9. Treatment System for Removing Halogenated Compounds from Contaminated Sources

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Yestrebsky, Cherie L. (Inventor)

    2015-01-01

    A treatment system and a method for removal of at least one halogenated compound, such as PCBs, found in contaminated systems are provided. The treatment system includes a polymer blanket for receiving at least one non-polar solvent. The halogenated compound permeates into or through a wall of the polymer blanket where it is solubilized with at least one non-polar solvent received by said polymer blanket forming a halogenated solvent mixture. This treatment system and method provides for the in situ removal of halogenated compounds from the contaminated system. In one embodiment, the halogenated solvent mixture is subjected to subsequent processes which destroy and/or degrade the halogenated compound.

  10. Body Parts Removed during Surgery: A Useful Training Source

    ERIC Educational Resources Information Center

    Macchi, Veronica; Porzionato, Andrea; Stecco, Carla; Tiengo, Cesare; Parenti, Anna; Cestrone, Adriano; De Caro, Raffaele

    2011-01-01

    Current undergraduate medical curricula provides relatively little time for cadaver dissection. The Department of Human Anatomy and Physiology at the University of Padova has organized a pilot project with the University Hospital for the donation of body parts that are surgically removed for therapeutic purposes and destined under Italian law for…

  11. North America carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

    SciTech Connect

    King, Anthony W.; Hayes, Daniel J.; Huntzinger, Deborah N.; West, Tristram O.; Post, W. M.

    2012-12-01

    North America is both a source and sink of atmospheric CO2. Sources, predominately fossil-fuel combustion in the United States along with contributions from deforestation in Mexico, add CO2 to the atmosphere. Most North America ecosystems, particularly regrowing forests in the United States, are sinks for atmospheric CO2. CO2 is removed from the atmosphere in photosynthesis, converted into biomass and stored as carbon in vegetation, soil and wood products. Fossil-fuel emissions dominate the North American source-sink balance. North America is a net source of atmospheric CO2 with ecosystem sinks balancing approximately 35% of fossil-fuel CO2 emissions from North America.

  12. Carbon and nutrient removal from centrates and domestic wastewater using algal-bacterial biofilm bioreactors.

    PubMed

    Posadas, Esther; García-Encina, Pedro-Antonio; Soltau, Anna; Domínguez, Antonio; Díaz, Ignacio; Muñoz, Raúl

    2013-07-01

    The mechanisms of carbon and nutrient removal in an open algal-bacterial biofilm reactor and an open bacterial biofilm reactor were comparatively evaluated during the treatment of centrates and domestic wastewater. Comparable carbon removals (>80%) were recorded in both bioreactors, despite the algal-bacterial biofilm supported twice higher nutrient removals than the bacterial biofilm. The main carbon and nitrogen removal mechanisms in the algal-bacterial photobioreactor were assimilation into algal biomass and stripping, while stripping accounted for most carbon and nitrogen removal in the bacterial biofilm. Phosphorus was removed by assimilation into algal-bacterial biomass while no effective phosphorous removal was observed in the bacterial biofilm. Carbon, nitrogen and phosphorus removals of 91 ± 3%, 70 ± 8% and 85 ± 9%, respectively, were recorded in the algal-bacterial bioreactor at 10d of hydraulic retention time when treating domestic wastewater. However, the high water footprint recorded (0.5-6.7 Lm(-2)d(-1)) could eventually compromise the environmental sustainability of this microalgae-based technology. PMID:23644070

  13. Cyclic process for producing methane from carbon monoxide with heat removal

    DOEpatents

    Frost, Albert C.; Yang, Chang-lee

    1982-01-01

    Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

  14. Source attribution of black carbon in Arctic snow.

    PubMed

    Hegg, Dean A; Warren, Stephen G; Grenfell, Thomas C; Doherty, Sarah J; Larson, Timothy V; Clarke, Antony D

    2009-06-01

    Snow samples obtained at 36 sites in Alaska, Canada, Greenland, Russia, and the Arctic Ocean in early 2007 were analyzed for light-absorbing aerosol concentration together with a suite of associated chemical species. The light absorption data, interpreted as black carbon concentrations, and other chemical data were input into the EPA PMF 1.1 receptor model to explore the sources for black carbon in the snow. The analysis found four factors or sources: two distinct biomass burning sources, a pollution source, and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources (encompassing both open and closed combustion) together accounting for >90% of the black carbon. PMID:19569324

  15. Performance of Spent Mushroom Farming Waste (SMFW) Activated Carbon for Ni (II) Removal

    NASA Astrophysics Data System (ADS)

    Desa, N. S. Md; Ghani, Z. Ab; Talib, S. Abdul; Tay, C. C.

    2016-07-01

    The feasibility of a low cost agricultural waste of spent mushroom farming waste (SMFW) activated carbon for Ni(II) removal was investigated. The batch adsorption experiments of adsorbent dosage, pH, contact time, metal concentration, and temperature were determined. The samples were shaken at 125 rpm, filtered and analyzed using ICP-OES. The fifty percent of Ni(II) removal was obtained at 0.63 g of adsorbent dosage, pH 5-6 (unadjusted), 60 min contact time, 50 mg/L Ni(II) concentration and 25 °C temperature. The evaluated SMFW activated carbon showed the highest performance on Ni(II) removal compared to commercial Amberlite IRC86 resin and zeolite NK3. The result indicated that SMFW activated carbon is a high potential cation exchange adsorbent and suitable for adsorption process for metal removal. The obtained results contribute toward application of developed SMFW activated carbon in industrial pilot study.

  16. Stability Of A Carbon-Dioxide-Removing Resin

    NASA Technical Reports Server (NTRS)

    Wydeven, Theodore; Wood, Peter

    1990-01-01

    Report describes experiments determing long-term chemical stability of IRA-45, commerical ion-exchange resin candidate for use in removing CO2 from atmosphere of Space Station. In proposed system, cabin air passes through resin, and acidic CO2 absorbed by weakly-basic hydrated diethylenetriamine bonded to porous resin substrate. When resin absorbs all CO2, disconnects from airstream and heated with steam to desorb CO2. Resin reuseable. Removed by post-treating process air with phosphoric acid on charcoal. Other chemicals removed by trace-contaminant-control subsystem of Space Station.

  17. Adsorptive removal of Zn(II) ion from aqueous solution using rice husk-based activated carbon

    NASA Astrophysics Data System (ADS)

    Taha, Mohd F.; Ibrahim, Muhammad H. C.; Shaharun, Maizatul S.; Chong, F. K.

    2012-09-01

    The study of rice husk-based activated carbon as a potential low-cost adsorbent for the removal of Zn(II) ion from aqueous solution was investigated. Rice husk, an agricultural waste, is a good alternative source for cheap precursor of activated carbon due to its abundance and constant availability. In this work, rice husk-based activated carbon was prepared via chemical treatment using NaOH as an activation agent prior the carbonization process. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon carbonized at 650°C, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). Other analyses were also conducted on these samples using fourier transmitter infrared spectroscopy (FTIR), CHN elemental analyzer and X-ray diffraction (XRD) for characterization study. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were found to be 255 m2/g and 0.17 cm2/g, respectively. The adsorption studies for the removal of Zn(II) ion from aqueous solution were carried out as a function of varied contact time at room temperature. The concentration of Zn(II) ion was analyzed using atomic absorption spectrophotometer (AAS). The results obtained from adsorption studies indicate the potential of rice husk as an economically promising precursor for the preparation of activated carbon for removal of Zn(II) ion from aqueous solution.

  18. Wine wastes as carbon source for biological treatment of acid mine drainage.

    PubMed

    Costa, M C; Santos, E S; Barros, R J; Pires, C; Martins, M

    2009-05-01

    Possible use of wine wastes containing ethanol as carbon and energy source for sulphate-reducing bacteria (SRB) growth and activity in the treatment of acid mine drainage (AMD) is studied for the first time. The experiments were performed using anaerobic down-flow packed bed reactors in semi-continuous systems. The performance of two bioreactors fed with wine wastes or ethanol as carbon sources is compared in terms of sulphate reduction, metals removal and neutralization. The results show that efficient neutralization and high sulphate removal (>90%) were attained with the use of wine wastes as substrate allowing the production of effluents with concentrations below the required local legislation for irrigation waters. This is only possible provided that the AMD and wine wastes are contacted with calcite tailing, a waste material that neutralizes and provides buffer capacity to the medium. The removal of metals using wine wastes as carbon source was 61-91% for Fe and 97% for both Zn and Cu. The lower removal of iron, when wine waste is used instead of ethanol, may be due to the presence of iron-chelating compounds in the waste, which prevent the formation of iron sulphide, and partial unavailability of sulphide because of re-oxidation to elemental sulphur. However, that did not affect significantly the quality of the effluent for irrigation. This work demonstrates that wine wastes are a potential alternative to traditional SRB substrates. This finding has direct implication to sustainable operation of SRB bioreactors for AMD treatment. PMID:19201010

  19. Sulphate reduction and the removal of carbon and ammonia in a laboratory-scale constructed wetland.

    PubMed

    Wiessner, A; Kappelmeyer, U; Kuschk, P; Kästner, M

    2005-11-01

    Sulphate is a normal constituent of domestic wastewater and reduced sulphur compounds are known to be potent inhibitors of plant growth and certain microbial activities. However, the knowledge about sulphate reduction and the effect on the removal of C and N in constructed wetlands is still limited. Investigations in laboratory-scale constructed wetland reactors were performed to evaluate the interrelation of carbon and nitrogen removal with the sulphate reduction by use of artificial domestic wastewater. Carbon removal was found to be only slightly affected and remained at high levels of efficiency (75-90%). Only at sulphate reduction intensities above 75 mgl(-1) (50% removal), a decrease of carbon removal of up to 20% was observed. A highly contrary behaviour of ammonia removal was found in general, which decreased exponentially from 75% to 35% related to a linear increase of sulphate reduction up to 75 mgl(-1) (50% removal). Since sulphate removal is considered to be dependant on the load of electron donors, the carbon load of the system was varied. Variation of the load changed the intensities of sulphate reduction immediately, but did not influence the carbon removal effectiveness. Doubling of the carbon concentration of 200 mgl(-1) BOD(5) for domestic wastewater usually led to sulphate reduction of up to 150 mgl(-1) (100% removal). The findings show that, particularly in constructed wetland systems, the sulphur cycle in the rhizosphere is of high importance for performance of the waste water treatment and may initiate a reconsideration of the amount of sulphate present in the tap water systems. PMID:16246395

  20. Dopamine as a Carbon Source: The Controlled Synthesis of Hollow Carbon Spheres and Yolk-Structured Carbon Nanocomposites

    SciTech Connect

    Dai, Sheng; Liu, Rui; Mahurin, Shannon Mark; Li, Chen; Unocic, Raymond R; Idrobo Tapia, Juan C; Gao, Hongjun; Pennycook, Stephen J

    2011-01-01

    A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au{at}Carbon nanocomposites. The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au{at}C nanocomposites are catalytically active.

  1. PERFORMANCE AND MODELING OF A HOT POTASSIUM CARBONATE ACID GAS REMOVAL SYSTEM IN TREATING COAL GAS

    EPA Science Inventory

    The report discusses the performance and modeling of a hot potassium carbonate (K2CO3) acid gas removal system (AGRS) in treating coal gas. Aqueous solutions of K2CO3, with and without amine additive, were used as the acid gas removal solvent in the Coal Gasification/Gas Cleaning...

  2. REMOVING WATER-SOLUBLE HAZARDOUS MATERIAL SPILLS FROM WATERWAYS WITH CARBON

    EPA Science Inventory

    A model for the removal of water-soluble organic materials from water by carbon-filled, buoyant packets and panels is described. Based on this model, equations are derived for the removal of dissolved organic compounds from waterways by buoyant packets that are either (a) cycled ...

  3. A comparison of black carbon measurement methods for combustion sources

    NASA Astrophysics Data System (ADS)

    Holder, A. L.; Pavlovic, J.; Yelverton, T.; Hagler, G.; Aurell, J.; Ebersviller, S.; Seay, B.; Jetter, J.; Gullett, B.; Hays, M. D.

    2015-12-01

    Black carbon is an important short-term climate forcer that has been linked with adverse health effects. Multiple black carbon measurement methodologies exist, but no standard measurement method or calibration material has been agreed upon. Moreover, the U.S. Environmental Protection Agency uses elemental carbon in its ambient monitoring networks and in its emissions inventory, assuming that elemental carbon is equivalent to black carbon. Instrument comparisons with ambient aerosols have demonstrated considerable differences between black carbon and elemental carbon, as well as among different black carbon measurements. However, there have been few published comparable studies for source emissions. We used multiple measurement methods to quantify black carbon and elemental carbon emissions from a range of combustion sources (diesel gensets, coal fired boilers, prescribed fires and cookstoves) emitting particles of varying composition and physical characteristics. The ratio of black carbon to elemental carbon (BC/EC) ranged from 0.50 to 2.8 and depended upon the combustion source. The greatest agreement was observed for emissions from cookstoves (BC/EC = 1.1 ± 0.3). The largest differences were seen for emissions from large stationary diesel genset (BC/EC = 2.3 ± 0.5) and were most pronounced when a diesel particulate filter was used (BC/EC 2.5 ± 0.6). This suggests that this source category may be underrepresented in emissions inventories based on elemental carbon. Black carbon concentrations derived from filter-based attenuation were highly correlated with photo-acoustic absorption measurements, but were generally 50% greater. This is likely due to the choice of calibration factor, which is currently ambiguously defined. These results highlight the importance of developing a standard calibration material to improve comparability among measurements.

  4. Comparison of NOx Removal Efficiencies in Compost Based Biofilters Using Four Different Compost Sources

    SciTech Connect

    Lacey, Jeffrey Alan; Lee, Brady Douglas; Apel, William Arnold

    2001-06-01

    In 1998, 3.6 trillion kilowatt-hours of electricity were generated in the United States. Over half of this was from coal-fired power plants, resulting in more than 8.3 million tons of nitrogen oxide (NOx) compounds being released into the environment. Over 95% of the NOx compounds produced during coal combustion are in the form of nitric oxide (NO). NOx emission regulations are becoming increasingly stringent, leading to the need for new, cost effective NOx treatment technologies. Biofiltration is such a technology. NO removal efficiencies were compared in compost based biofilters using four different composts. In previous experiments, removal efficiencies were typically highest at the beginning of the experiment, and decreased as the experiments proceeded. This work tested different types of compost in an effort to find a compost that could maintain NO removal efficiencies comparable to those seen early in the previous experiments. One of the composts was wood based with manure, two were wood based with high nitrogen content sludge, and one was dairy compost. The wood based with manure and one of the wood based with sludge composts were taken directly from an active compost pile while the other two composts were received in retail packaging which had been out of active piles for an indeterminate amount of time. A high temperature (55-60°C) off-gas stream was treated in biofilters operated under denitrifying conditions. Biofilters were operated at an empty bed residence time of 13 seconds with target inlet NO concentrations of 500 ppmv. Lactate was the carbon and energy source. Compost was sampled at 10-day intervals to determine aerobic and anaerobic microbial densities. Compost was mixed at a 1:1 ratio with lava rock and calcite was added at 100g/kg of compost. In each compost tested, the highest removal efficiencies occurred within the first 10 days of the experiment. The wood based with manure peaked at day 3 (77.14%), the dairy compost at day 1 (80.74%), the

  5. Optimization of VFAs and ethanol production with waste sludge used as the denitrification carbon source.

    PubMed

    Guo, Liang; Zhang, Jiawen; Yin, Li; Zhao, Yangguo; Gao, Mengchun; She, Zonglian

    2015-01-01

    An acidification metabolite such as volatile fatty acids (VFAs) and ethanol could be used as denitrification carbon sources for solving the difficult problem of carbon source shortages and low nitrogen removal efficiency. A proper control of environmental factors could be essential for obtaining the optimal contents of VFAs and ethanol. In this study, suspended solids (SS), oxidation reduction potential (ORP) and shaking rate were chosen to investigate the interactive effects on VFAs and ethanol production with waste sludge. It was indicated that T-VFA yield could be enhanced at lower ORP and shaking rate. Changing the SS, ORP and shaking rate could influence the distribution of acetic, propionic, butyric, valeric acids and ethanol. The optimal conditions for VFAs and ethanol production used as a denitrification carbon source were predicted by analyzing response surface methodology (RSM). PMID:26465305

  6. A new activated primary tank developed for recovering carbon source and its application.

    PubMed

    Jin, Pengkang; Wang, Xianbao; Zhang, Qionghua; Wang, Xiaochang; Ngo, Huu Hao; Yang, Lei

    2016-01-01

    A novel activated primary tank process (APT) was developed for recovering carbon source by fermentation and elutriation of primary sludge. The effects of solids retention time (SRT), elutriation intensity (G) and return sludge ratio (RSR) on this recovery were evaluated in a pilot scale reactor. Results indicated that SRT significantly influenced carbon source recovery, and mechanical elutriation could promote soluble COD (SCOD) and VFA yields. The optimal conditions of APT were SRT=5d, G=152s(-1) and RSR=10%, SCOD and VFA production were 57.0mg/L and 21.7mg/L. Particulate organic matter in sludge was converted into SCOD and VFAs as fermentative bacteria were significantly enriched in APT. Moreover, the APT process was applied in a wastewater treatment plant to solve the problem of insufficient carbon source. The outcomes demonstrated that influent SCOD of biological tank increased by 31.1%, which improved the efficiency of removing nitrogen and phosphorus. PMID:26562688

  7. Growth of graphene films from non-gaseous carbon sources

    DOEpatents

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  8. Removing the effects of metamorphism from the Neoproterozoic carbon isotope record: a case study on Islay, western Scotland

    NASA Astrophysics Data System (ADS)

    Skelton, Alasdair

    2016-04-01

    The Port Askaig Formation on Islay, western Scotland is the first discovered tillite (glacial sediment) of Neoproterozoic age. This formation is sandwiched between carbonate rocks which preserve an extreme negative carbon isotope excursion. This so called "Islay anomaly" has been correlated with other such anomalies worldwide and together with the tillites has been cited as evidence of major (worldwide) glaciation events. During subsequent mountain building, this carbonate-tillite- carbonate sequence has been folded, producing a major en-echelon anticlinal fold system. Folding was accompanied by metamorphism at greenschist facies conditions which was, in turn, accompanied by metamorphic fluid flow. Mapping of the δ18O and δ13C values of these carbonate rocks reveals that metamorphic fluids were channelled through the axial region of the anticlinal fold. The metamorphic fluid was found to have a highly negative δ13C value, which was found to be in equilibrium with metamorphosed graphitic mudstones beneath the carbonate-tillite-carbonate sequence. Devolatilisation of these mudstones is therefore a likely source of this metamorphic fluid. Removal of the effects of metamorphic fluid flow on δ13C values recorded by metamorphosed carbonate rocks on Islay allows us to re-evaluate the isotopic evidence used to reconstruct Neoproterozoic climate. We are able to show that extreme negative δ13C values can partly be attributed to metamorphic fluid flow.

  9. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse. PMID:22380206

  10. Shunting arc plasma source for pure carbon ion beama)

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm2 at the peak of the pulse.

  11. Nitrate removal, communities of denitrifiers and adverse effects in different carbon substrates for use in denitrification beds

    PubMed Central

    Warneke, Sören; Schipper, Louis A.; Matiasek, Michael G.; Scow, Kate M.; Cameron, Stewart; Bruesewitz, Denise A.; McDonald, Ian R.

    2012-01-01

    Denitrification beds are containers filled with wood by-products that serve as a carbon and energy source to denitrifiers, which reduce nitrate ( NO3−) from point source discharges into non-reactive dinitrogen (N2) gas. This study investigates a range of alternative carbon sources and determines rates, mechanisms and factors controlling NO3− removal, denitrifying bacterial community, and the adverse effects of these substrates. Experimental barrels (0.2 m3) filled with either maize cobs, wheat straw, green waste, sawdust, pine woodchips or eucalyptus woodchips were incubated at 16.8 °C or 27.1 °C (outlet temperature), and received NO3− enriched water (14.38 mg N L−1 and 17.15 mg N L−1). After 2.5 years of incubation measurements were made of NO3−−N removal rates, in vitro denitrification rates (DR), factors limiting denitrification (carbon and nitrate availability, dissolved oxygen, temperature, pH, and concentrations of NO3−, nitrite and ammonia), copy number of nitrite reductase (nirS and nirK ) and nitrous oxide reductase (nosZ ) genes, and greenhouse gas production (dissolved nitrous oxide (N2O) and methane), and carbon (TOC) loss. Microbial denitrification was the main mechanism for NO3−−N removal. Nitrate–N removal rates ranged from 1.3 (pine woodchips) to 6.2 g N m−3 d−1 (maize cobs), and were predominantly limited by C availability and temperature (Q10 = 1.2) when NO3−−N outlet concentrations remained above 1 mg L−1. The NO3−−N removal rate did not depend directly on substrate type, but on the quantity of microbially available carbon, which differed between carbon sources. The abundance of denitrifying genes (nirS, nirK and nosZ ) was similar in replicate barrels under cold incubation, but varied substantially under warm incubation, and between substrates. Warm incubation enhanced growth of nirS containing bacteria and bacteria that lacked the nosZ gene, potentially explaining the greater N2O emission in warmer

  12. Removal of carbon dioxide by a spray dryer.

    PubMed

    Chen, Jyh-Cherng; Fang, Guor-Cheng; Tang, Jun-Tian; Liu, Li-Ping

    2005-03-01

    With the global warming due to greenhouse effects becoming serious, many efforts are carried out to decrease the emissions of CO2 from the combustion of carbonaceous materials. In Taiwan, there are 19 large-scale municipal solid waste incinerators running and their total emission of CO2 is about 16,950 kton y-1. Spray dryer is the most prevailing air pollution control devise for removing acid gas in waste incineration; however, the performance of spray dryer on the removal of CO2 is seldom studied. This study employs a laboratory-scale spray dryer to investigate the removal efficiency of CO2 under different operating conditions. The evaluated parameters include different absorbents mixed with CaOH2, operating temperature, the concentration of absorbent, and the inlet concentration of CO2. Experimental results show that the best removal efficiency of CO2 by a spray dryer is 48% as the absorbent is 10%NaOH+5%CaOH2 and the operating temperature is 150 degrees C. Comparing this result with previous study shows that the performance of spray dryer is better than traditional NaOH wet scrubber. For NaOH+CaOH2 spray dryer, the removal efficiency of CO2 is decreased with the inlet concentration of CO2 increased and the optimum operating temperature is 150 degrees C. Except NaOH+CaOH2, absorbents DEA+CaOH2, TEA+CaOH2, and single CaOH2 are not effective in removing CO2 by a spray dryer. PMID:15698650

  13. Performance and recent improvement in microbial fuel cells for simultaneous carbon and nitrogen removal: A review.

    PubMed

    Sun, Haishu; Xu, Shengjun; Zhuang, Guoqiang; Zhuang, Xuliang

    2016-01-01

    Microbial fuel cells (MFCs) have become a promising technology for wastewater treatment accompanying electricity generation. Carbon and nitrogen removal can be achieved by utilizing the electron transfer between the anode and cathode in an MFC. However, large-scale power production and high removal efficiency must be achieved at a low cost to make MFCs practical and economically competitive in the future. This article reviews the principles, feasibility and bottlenecks of MFCs for simultaneous carbon and nitrogen removal, the recent advances and prospective strategies for performance improvement, as well as the involved microbes and electron transfer mechanisms. PMID:26899662

  14. Removal of Technetium, Carbon Tetrachloride, and Metals from DOE Properties.

    SciTech Connect

    Mallouk, Thomas E.; Ponder, Sherman M.; Darab, John

    2000-06-01

    The objective of this research is to prepare, characterize, and evaluate new materials for the removal of technetium (Tc) compounds, halogenated organics, and other troublesome metals from DOE waste streams and contaminated areas. This work follows the discovery that a nanoscale form of zero-valent iron, dispersed on high surface area supports, reduces metal ions (Cr, Hg, Pb, Cd) and Re (as a surrogate for Tc) to insoluble forms faster and with higher efficiency than does unsupported iron. Liquid-liquid extraction methods are also being developed for quantitative removal of Cs from tetraphenylborate salt mixtures, which are generated in waste processing at Savannah River, and conversion to vitrifiable inorganic Cs salts.

  15. Arsenic Removal Technologies and the Effect of Source Water Quality on Performance

    SciTech Connect

    KHANDAKER, NADIM R.; BRADY, PATRICK V.

    2002-07-01

    Arsenic removal technologies that are effective at the tens of ppb level include coagulation, followed by settling/microfiltration, ion exchange by mineral surfaces,and pressure-driven membrane processes (reverse osmosis, nanofiltration and ultrafiltration). This report describes the fundamental mechanisms of operation of the arsenic removal systems and addresses the critical issues of arsenic speciation, source water quality on the performance of the arsenic removal systems and costs associated with the different treatment technology categories.

  16. Performances of toluene removal by activated carbon derived from durian shell.

    PubMed

    Tham, Y J; Latif, Puziah Abdul; Abdullah, A M; Shamala-Devi, A; Taufiq-Yap, Y H

    2011-01-01

    In the effort to find alternative low cost adsorbent for volatile organic vapors has prompted this research in assessing the effectiveness of activated carbon produced from durian shell in removing toluene vapors. Durian shells were impregnated with different concentrations of H3PO4 followed by carbonization at 500 °C for 20 min under nitrogen atmosphere. The prepared durian shell activated carbon (DSAC) was characterized for its physical and chemical properties. The removal efficiency of toluene by DSAC was performed using different toluene concentrations. Results showed that the highest BET surface area of the produced DSAC was 1404 m2/g. Highest removal efficiency of toluene vapors was achieved by using DSAC impregnated with 30% of acid concentration heated at 500 °C for 20 min heating duration. However, there is insignificant difference between removal efficiency of toluene by DSAC and different toluene concentrations. The toluene adsorption by DSAC was better fitted into Freundlich model. PMID:20884200

  17. Granular activated carbon for removal of organic matter and turbidity from secondary wastewater.

    PubMed

    Hatt, J W; Germain, E; Judd, S J

    2013-01-01

    A range of commercial granular activated carbon (GAC) media have been assessed as pretreatment technologies for a downstream microfiltration (MF) process. Media were assessed on the basis of reduction in both organic matter and turbidity, since these are known to cause fouling in MF membranes. Isotherm adsorption analysis through jar testing with supplementary column trials revealed a wide variation between the different adsorbent materials with regard to organics removal and adsorption kinetics. Comparison with previous work using powdered activated carbon (PAC) revealed that for organic removal above 60% the use of GAC media incurs a significantly lower carbon usage rate than PAC. All GACs tested achieved a minimum of 80% turbidity removal. This combination of turbidity and organic removal suggests that GAC would be expected to provide a significant reduction in fouling of a downstream MF process with improved product water quality. PMID:23306264

  18. Effect of powdered activated carbon technology on short-cut nitrogen removal for coal gasification wastewater.

    PubMed

    Zhao, Qian; Han, Hongjun; Xu, Chunyan; Zhuang, Haifeng; Fang, Fang; Zhang, Linghan

    2013-08-01

    A combined process consisting of a powdered activated carbon technology (PACT) and short-cut biological nitrogen removal reactor (SBNR) was developed to enhance the removal efficiency of the total nitrogen (TN) from the effluent of an upflow anaerobic sludge bed (UASB) reactor, which was used to treat coal gasification wastewater (CGW). The SBNR performance was improved with the increasing of COD and TP removal efficiency via PACT. The average removal efficiencies of COD and TP in PACT were respectively 85.80% and 90.30%. Meanwhile, the NH3-N to NO2-N conversion rate was achieved 86.89% in SBNR and the total nitrogen (TN) removal efficiency was 75.54%. In contrast, the AOB in SBNR was significantly inhibited without PACT or with poor performance of PACT in advance, which rendered the removal of TN. Furthermore, PAC was demonstrated to remove some refractory compounds, which therefore improved the biodegradability of the coal gasification wastewater. PMID:23735800

  19. Activated carbon from leather shaving wastes and its application in removal of toxic materials.

    PubMed

    Kantarli, Ismail Cem; Yanik, Jale

    2010-07-15

    In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass. PMID:20382474

  20. Removal of toxic Cr(VI) by the adsorption of activated carbons prepared from Simarouba shells.

    PubMed

    Neelavathi, A; Sekhar, K B Chandra; Babu, C Ramesh; Jayaveera, K N

    2004-04-01

    Removal of toxic Cr(VI) in aqueous medium was investigated using activated carbon adsorbents prepared from Simarouba glauca seed shells. The pH effect, Cr(VI) concentration, adsorbent dosage and contact time period were studied in batch experiment. The removal of Cr(VI) was in general most effective at pH range 2.0-4.0 and high Cr(VI) concentrations. Activated carbons are prepared at 80050 degrees C temperature. One is non-impregnated and the remaining three are impregnated with zinc chloride in 1:1,1:2,1:3 ratio. Important characteristics of activated carbons are also investigated. The data for all the adsorbents fit well to the Freundlich adsorption isotherm. The removal of Cr(VI) is around 97% was observed with 1:2 impregnated activated carbon at pH 3.0 where as other adsorbents showed much lower activities. PMID:16649604

  1. Performance evaluation of waste activated carbon on atrazine removal from contaminated water.

    PubMed

    Ghosh, Pranab Kumar; Philip, Ligy

    2005-01-01

    In this study, the potential of spent activated carbon from water purifier (Aqua Guard, India) for the removal of atrazine (2 chloro-4 ethylamino-6-isopropylamino-1, 3, 5 triazine) from wastewaters was evaluated. Different grades of spent activated carbon were prepared by various pretreatments. Based on kinetic and equilibrium study results, spent activated carbon with a grain size of 0.3-0.5 mm and washed with distilled water (designated as WAC) was selected for fixed column studies. Batch adsorption equilibrium data followed both Freundlich and Langmuir isotherm. Fixed bed adsorption column with spent activated carbon as adsorbent was used as a polishing unit for the removal of atrazine from the effluent of an upflow anaerobic sludge blanket (UASB) reactor treating atrazine bearing domestic wastewater. Growth of bacteria on the surface of WAC was observed during column study and bacterial activity enhanced the effectiveness of adsorbent on atrazine removal from wastewater. PMID:15913015

  2. METHOD FOR MEASURING CARBON FIBER EMISSIONS FROM STATIONARY SOURCES

    EPA Science Inventory

    Carbon fibers are highly conductive, lightweight and of small dimensions. When released as emissions from production, manufacturing, processing and disposal sources they may become airborne and disperse over wide areas. If they settle onto electronic or electrical components they...

  3. Carbon Dioxide Removal Troubleshooting aboard the International Space Station (ISS) during Space Shuttle (STS) Docked Operations

    NASA Technical Reports Server (NTRS)

    Matty, Christopher M.; Cover, John M.

    2009-01-01

    The International Space Station (ISS) represents a largely closed-system habitable volume which requires active control of atmospheric constituents, including removal of exhaled Carbon Dioxide (CO2). The ISS provides a unique opportunity to observe system requirements for (CO2) removal. CO2 removal is managed by the Carbon Dioxide Removal Assembly (CDRA) aboard the US segment of ISS and by Lithium Hydroxide (LiOH) aboard the Space Shuttle (STS). While the ISS and STS are docked, various methods are used to balance the CO2 levels between the two vehicles, including mechanical air handling and management of general crew locations. Over the course of ISS operation, several unexpected anomalies have occurred which have required troubleshooting, including possible compromised performance of the CDRA and LiOH systems, and possible imbalance in CO2 levels between the ISS and STS while docked. This paper will cover efforts to troubleshoot the CO2 removal systems aboard the ISS and docked STS.

  4. Net removal of dissolved organic carbon in the subsurface Black Sea

    NASA Astrophysics Data System (ADS)

    Margolin, A. R.; Gerringa, L. J.; Hansell, D. A.; Rijkenberg, M. J. A.

    2015-12-01

    Dissolved organic carbon (DOC) concentrations in the deep Black Sea are ~2.5 times higher than found in the global ocean. The two major external sources of DOC are rivers and the Mediterranean, while expansive phytoplankton blooms contribute autochthonous carbon to the Black Sea's ~800 Tg C DOC reservoir. Here, a basin-wide zonal section of DOC is explored using data from the 2013 Dutch GEOTRACES GA04-N "MedBlack" cruise 64PE373. DOC distributions are interpreted with respect to well-described hydrographic and biogeochemical layers of the Black Sea. DOC concentrations were >180 µmol kg-1 at the surface, decreasing to ~125 µmol kg-1 at the base of the oxic layer and reaching a minimum of ~113 µmol kg-1 in the upper anoxic layer between ~150 and 500 m. Maximum anoxic layer concentrations of 122 µmol kg-1 were found in the homogeneous benthic bottom layer (>1775 m). Determined from the relationship of DOC with salinity, we found that ~34-41 µmol kg-1 was removed from the basin's oxic layer in <5 years, and an additional 13 ± 5 µmol kg-1 was removed from the anoxic layer during its ~300-600 years residence time, given steady state. We find no evidence for DOC accumulation in the anoxic Black Sea, and suggest that concentrations are elevated relative to the ocean due to input of terrigenous DOC from rivers. The Black Sea's relatively elevated DOC pool may be analogous to the previously hypothesized anoxic Eocene ocean's elevated reservoir if the Eocene ocean received a substantial amount of terrigenous DOC from rivers.

  5. Enhanced life ion source for germanium and carbon ion implantation

    SciTech Connect

    Hsieh, Tseh-Jen; Colvin, Neil; Kondratenko, Serguei

    2012-11-06

    Germanium and carbon ions represent a significant portion of total ion implantation steps in the process flow. Very often ion source materials that used to produce ions are chemically aggressive, especially at higher temperatures, and result in fast ion source performance degradation and a very limited lifetime [B.S. Freer, et. al., 2002 14th Intl. Conf. on Ion Implantation Technology Proc, IEEE Conf. Proc., p. 420 (2003)]. GeF{sub 4} and CO{sub 2} are commonly used to generate germanium and carbon beams. In the case of GeF{sub 4} controlling the tungsten deposition due to the de-composition of WF{sub 6} (halogen cycle) is critical to ion source life. With CO{sub 2}, the materials oxidation and carbon deposition must be controlled as both will affect cathode thermionic emission and anti-cathode (repeller) efficiencies due to the formation of volatile metal oxides. The improved ion source design Extended Life Source 3 (Eterna ELS3) together with its proprietary co-gas material implementation has demonstrated >300 hours of stable continuous operation when using carbon and germanium ion beams. Optimizing cogas chemistries retard the cathode erosion rate for germanium and carbon minimizes the adverse effects of oxygen when reducing gas is introduced for carbon. The proprietary combination of hardware and co-gas has improved source stability and the results of the hardware and co-gas development are discussed.

  6. Seaweeds and halophytes to remove carbon from the atmosphere

    SciTech Connect

    Glenn, E.P.; Kent, K.J.; Thompson, T.L.; Frye, R.J. . Environmental Research Lab.)

    1991-02-01

    The utility industry and other interested parties have investigated strategies to mitigate the buildup of atmospheric CO{sub 2}. One option that has been considered is the planting of trees on a massive scale to absorb carbon through photosynthesis. A dilemma of using tree plantations, however, is that they might occupy land that will be needed for food production or other needs for an expected doubling of human population in the tropical regions. We evaluated seaweeds and salt-tolerant terrestrial plants (halophytes) to be grown on the coastal shelves and salt deserts of the world as possible alternatives to tree plantations. An estimated 1.3 {times} 10{sup 6} km{sup 2} of continental shelf and 1.3 {times} 10{sup 6} km{sup 2} of salt desert may be usable for seaweed and halophyte plantations. The production rates of managed seaweed and halophyte plantings are similar to managed tree plantations. Seaweeds and halophytes could conceivably absorb 10--20% of annual fossil fuel carbon emissions through biomass production, similar to estimates made for tree plantations. Present costs of halophyte biomass production are similar to costs of tree biomass production, whereas seaweed biomass is much more expensive to produce using existing technologies. Storage of seaweed carbon might be accomplished by allowing it to enter the sediment detritus chain whereas halophyte carbon might be sequestered in the soil, or used as biomass fuel. As has been concluded for reforestation, these saline biomass crops could at best help delay rather than solve the carbon dioxide build-up problem. 1 fig., 13 tabs.

  7. Removal of benzene and toluene by carbonized bamboo materials modified with TiO2.

    PubMed

    Chuang, Chih Shen; Wang, Ming-Kuang; Ko, Chun-Han; Ou, Chia-Chih; Wu, Chien-Hou

    2008-03-01

    Carbonized moso bamboo (Phyllostachys pubescens) was coated with TiO(2) nanoparticles to enhance its removal efficiency of harmful gases. Carbonized bamboo-TiO(2) composite (CBC) was prepared by heating mixtures of carbonized bamboo powder (CB) and TiO(2) nanoparticles, denoted as CBM, under nitrogen condition. TiO(2) nanoparticle and carbonized bamboo powder were mixed with the mass ratios of 1/1 and 2/1, respectively. At the same mass ratio of TiO(2) to CB, the benzene and toluene removal efficiencies follow the trend: CBC>CBM>CB, which is consistent with the amount of TiO(2) validated by elemental analysis. Sorption mechanism of benzene and toluene by CB, CBM and CBC might belong to hydrophobic-hydrophobic interaction, observed by depletion of untreated bamboo (UB) carbohydrates during carbonization. Sorption kinetics was further analyzed, and optimal correlation was found by fitting with the Elovich kinetic equation. PMID:17459699

  8. Simultaneous removal of dissolved organic matter and bromide from drinking water source by anion exchange resins for controlling disinfection by-products.

    PubMed

    Phetrak, Athit; Lohwacharin, Jenyuk; Sakai, Hiroshi; Murakami, Michio; Oguma, Kumiko; Takizawa, Satoshi

    2014-06-01

    Anion exchange resins (AERs) with different properties were evaluated for their ability to remove dissolved organic matter (DOM) and bromide, and to reduce disinfection by-product (DBP) formation potentials of water collected from a eutrophic surface water source in Japan. DOM and bromide were simultaneously removed by all selected AERs in batch adsorption experiments. A polyacrylic magnetic ion exchange resin (MIEX®) showed faster dissolved organic carbon (DOC) removal than other AERs because it had the smallest resin bead size. Aromatic DOM fractions with molecular weight larger than 1600 Da and fluorescent organic fractions of fulvic acid- and humic acid-like compounds were efficiently removed by all AERs. Polystyrene AERs were more effective in bromide removal than polyacrylic AERs. This result implied that the properties of AERs, i.e. material and resin size, influenced not only DOM removal but also bromide removal efficiency. MIEX® showed significant chlorinated DBP removal because it had the highest DOC removal within 30 min, whereas polystyrene AERs efficiently removed brominated DBPs, especially brominated trihalomethane species. The results suggested that, depending on source water DOM and bromide concentration, selecting a suitable AER is a key factor in effective control of chlorinated and brominated DBPs in drinking water. PMID:25079839

  9. MASKING VERSUS REMOVING POINT SOURCES IN CMB DATA: THE SOURCE-CORRECTED WMAP POWER SPECTRUM FROM NEW EXTENDED CATALOG

    SciTech Connect

    Scodeller, Sandro; Hansen, Frode K. E-mail: frodekh@astro.uio.no

    2012-12-20

    In Scodeller et al., a new and extended point source catalog obtained from the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year data was presented. It includes most of the sources included in the standard WMAP seven-year point source catalogs as well as a large number of new detections. Here, we study the effects on the estimated CMB power spectrum when taking the newly detected point sources into consideration. We create point source masks for all the 2102 sources that we detected as well as a smaller one for the 665 sources detected in the Q, V, and W bands. We also create WMAP7 maps with point sources subtracted in order to compare with the spectrum obtained with source masks. The extended point source masks and point source cleaned WMAP7 maps are made publicly available. Using the proper residual correction, we find that the CMB power spectrum obtained from the point source cleaned map without any source mask is fully consistent with the spectrum obtained from the masked map. We further find that the spectrum obtained masking all 2102 sources is consistent with the results obtained using the standard WMAP seven-year point source mask (KQ85y7). We also verify that the removal of point sources does not introduce any skewness.

  10. A regenerable carbon dioxide removal and oxygen recovery system for the Japanese experiment module

    NASA Astrophysics Data System (ADS)

    Otsuji, K.; Hirao, M.; Satoh, S.

    The Japanese Space Station Program is now under Phase B study by the National Space Development Agency of Japan in participation with the U.S. Space Station Program. A Japanese Space Station participation will be a dedicated pressurized module to be attached to the U.S. Space Station, and is called Japanese Experiment Module (JEM). Astronaut scientists will conduct various experimental operations there. Thus an environment control and life support system is required. Regenerable carbon dioxide removal and collection technique as well as oxygen recovery technique has been studied and investigated for several years. A regenerable carbon dioxide removal subsystem using steam desorbed solid amine and an oxygen recovery subsystem using Sabatier methane cracking have a good possibility for the application to the Japanese Experiment Module. Basic performance characteristics of the carbon dioxide removal and oxygen recovery subsystem are presented according to the results of a fundamental performance test program. The trace contaminant removal process is also investigated and discussed. The solvent recovery plant for the regeneration of various industrial solvents, such as hydrocarbons, alcohols and so on, utilizes the multi-bed solvent adsorption and steam desorption process, which is very similar to the carbon dioxide removal subsystem. Therefore, to develop essential components including adsorption tank (bed), condensor, process controller and energy saving system, the technology obtained from the experience to construct solvent recovery plant can be easily and effectively applicable to the carbon dioxide removal subsystem. The energy saving efficiency is evaluated for blower power reduction, steam reduction and waste heat utilization technique. According to the above background, the entire environment control and life support system for the Japanese Experiment Module including the carbon dioxide removal and oxygen recovery subsystem is evaluated and proposed.

  11. Removal of N-nitrosodimethylamine precursors with powdered activated carbon adsorption.

    PubMed

    Beita-Sandí, Wilson; Ersan, Mahmut Selim; Uzun, Habibullah; Karanfil, Tanju

    2016-01-01

    The main objective of this study was to examine the roles of powdered activated carbon (PAC) characteristics (i.e., surface chemistry, pore size distribution, and surface area) in the removal of N-nitrosodimethylamine (NDMA) formation potential (FP) in surface and wastewater-impacted waters. Also, the effects of natural attenuation of NDMA precursors in surface waters, NDMA FP concentration, and carbon dose on the removal of NDMA FP by PAC were evaluated. Finally, the removal of NDMA FP by PAC at two full-scale DWTPs was monitored. Wastewater-impacted and surface water samples were collected to conduct adsorption experiments using different PACs and activated carbon fibers (ACFs) with a wide range of physicochemical characteristics. The removal efficiency of NDMA FP by PAC was significantly higher in wastewater-impacted than surface waters. Adsorbable NDMA precursors showed a size distribution in the waters tested; the adsorbable fraction included precursors accessing the pore size regions of 10-20 Å and <10 Å. Basic carbons showed higher removal of NDMA FP than acidic carbons on a surface area basis. The overall removal of NDMA FP by PAC on a mass basis depended on the surface area, pore size distribution and pHPZC. Thus, PACs with hybrid characteristics (micro and mesoporous), higher surface areas, and basic surface chemistry are more likely to be effective for NDMA precursor control by PAC adsorption. The application of PAC in DWTPs for taste and odor control resulted in an additional 20% removal of NDMA FP for the PAC doses of 7-10 mg/L. The natural attenuation of NDMA precursors through a combination of processes (biodegradation, photolysis and adsorption) decreased their adsorbability and removal by PAC adsorption. PMID:26584342

  12. Static and dynamic removal of aquatic natural organic matter by carbon nanotubes.

    PubMed

    Ajmani, Gaurav S; Cho, Hyun-Hee; Abbott Chalew, Talia E; Schwab, Kellogg J; Jacangelo, Joseph G; Huang, Haiou

    2014-08-01

    Carbon nanotubes (CNTs) were investigated for their capability and mechanisms to simultaneously remove colloidal natural organic matter (NOM) and humic substances from natural surface water. Static removal testing was conducted via adsorption experiments while dynamic removal was evaluated by layering CNTs onto substrate membranes and filtering natural water through the CNT-layered membranes. Analyses of treated water samples showed that removal of humic substances occurred via adsorption under both static and dynamic conditions. Removal of colloidal NOM occurred at a moderate level of 36-66% in static conditions, independent of the specific surface area (SSA) of CNTs. Dynamic removal of colloidal NOM increased from approximately 15% with the unmodified membrane to 80-100% with the CNT-modified membranes. Depth filtration played an important role in colloidal NOM removal. A comparison of the static and dynamic removal of humic substances showed that equilibrium static removal was higher than dynamic (p < 0.01), but there was also a significant linear relationship between static and dynamic removal (p < 0.05). Accounting for contact time of CNTs with NOM during filtration, it appeared that CNT mat structure was an important determinant of removal efficiencies for colloidal NOM and humic substances during CNT membrane filtration. PMID:24810742

  13. CO2 Removal using a Synthetic Analogue of Carbonic Anhydrase

    SciTech Connect

    Cordatos, Harry

    2010-09-14

    Project attempts to develop a synthetic analogue for carbonic anhydrase and incorporate it in a membrane for separation of CO2 from coal power plant flue gas. Conference poster presents result of first 9 months of project progress including concept, basic system architecture and membrane properties target, results of molecular modeling for analogue - CO2 interaction, and next steps of testing analogue resistance to flue gas contaminants.

  14. Reductions in contaminant mass discharge following partial mass removal from DNAPL source zones.

    PubMed

    Suchomel, Eric J; Pennell, Kurt D

    2006-10-01

    Although in situ remediation technologies have been used to aggressively treat dense nonaqueous phase liquid (DNAPL) source zones, complete contaminant removal or destruction is rarely achieved. To evaluate the effects of partial source zone mass removal on dissolved-phase contaminant flux, four experiments were conducted in a two-dimensional aquifer cell that contained a tetrachloroethene (PCE) source zone and down-gradient plume region. Initial source zone PCE saturation distributions, quantified using a light transmission system, were expressed in terms of a ganglia-to-pool ratio (GTP), which ranged from 0.16 (13.8% ganglia) to 1.6 (61.5% ganglia). The cells were flushed sequentially with a 4% (wt.) Tween 80 surfactant solution to achieve incremental PCE mass removal, followed by water flooding until steady-state mass discharge and plume concentrations were established. In all cases, the GTP ratio decreased with increasing mass removal, consistent with the observed preferential dissolution of PCE ganglia and persistence of high-saturation pools. In the ganglia-dominated system (GTP = 1.6), greater than 70% mass removal was required before measurable reductions in plume concentrations and mass discharge were observed. For pool-dominated source zones (GTP < 0.3), substantial reductions (>50%) in mass discharge were realized after only 50% mass removal. PMID:17051808

  15. Source contributions to atmospheric fine carbon particle concentrations

    NASA Astrophysics Data System (ADS)

    Andrew Gray, H.; Cass, Glen R.

    A Lagrangian particle-in-cell air quality model has been developed that facilitates the study of source contributions to atmospheric fine elemental carbon and fine primary total carbon particle concentrations. Model performance was tested using spatially and temporally resolved emissions and air quality data gathered for this purpose in the Los Angeles area for the year 1982. It was shown that black elemental carbon (EC) particle concentrations in that city were dominated by emissions from diesel engines including both on-highway and off-highway applications. Fine primary total carbon particle concentrations (TC=EC+organic carbon) resulted from the accumulation of small increments from a great variety of emission source types including both gasoline and diesel powered highway vehicles, stationary source fuel oil and gas combustion, industrial processes, paved road dust, fireplaces, cigarettes and food cooking (e.g. charbroilers). Strategies for black elemental carbon particle concentration control will of necessity need to focus on diesel engines, while controls directed at total carbon particle concentrations will have to be diversified over a great many source types.

  16. Bench to bedside review: Extracorporeal carbon dioxide removal, past present and future

    PubMed Central

    2012-01-01

    Acute respiratory distress syndrome (ARDS) has a substantial mortality rate and annually affects more than 140,000 people in the USA alone. Standard management includes lung protective ventilation but this impairs carbon dioxide clearance and may lead to right heart dysfunction or increased intracranial pressure. Extracorporeal carbon dioxide removal has the potential to optimize lung protective ventilation by uncoupling oxygenation and carbon dioxide clearance. The aim of this article is to review the carbon dioxide removal strategies that are likely to be widely available in the near future. Relevant published literature was identified using PubMed and Medline searches. Queries were performed by using the search terms ECCOR, AVCO2R, VVCO2R, respiratory dialysis, and by combining carbon dioxide removal and ARDS. The only search limitation imposed was English language. Additional articles were identified from reference lists in the studies that were reviewed. Several novel strategies to achieve carbon dioxide removal were identified, some of which are already commercially available whereas others are in advanced stages of development. PMID:23014710

  17. Removal of chromium from tannery industry effluents with (activated carbon and fly ash) adsorbents.

    PubMed

    Rao, S; Lade, H S; Kadam, T A; Ramana, T V; Krishnamacharyulu, S K G; Deshmukh, S; Gyananath, G

    2007-10-01

    Adsorption is a strong choice for removal operations as it is very simple to recover a high quality product from waste sludge. The efficiency of adsorbents like fly ash and activated carbon are tested based on their performance to remove chrome at various pH values, bed heights, and concentration of adsorbents. The removal efficiency was also tested for wastewater characteristics in a pilot plant in addition to the use of adsorbents. The concentration of chromium was determined by atomic absorption spectrophotometer (Perkin Elmer). The results depicted that the efficiency of removal increased with increasing pH and bed height and decreased with increasing concentration. The removal efficiency with fly ash as an adsorbent was comparatively better than activatedcarbon. Thus, adsorbents can be used for chromium removal from tannery industry effluent. PMID:18476371

  18. Denitrification using PBS as carbon source and biofilm support in a packed-bed bioreactor.

    PubMed

    Wu, Weizhong; Yang, Luhua; Wang, Jianlong

    2013-01-01

    Biodegradable polymer was used as carbon source and biofilm support for nitrate removal from aqueous solution as an attractive alternative for biological denitrification. The objective of this paper was to investigate the denitrification performance and microbial community of a packed-bed bioreactor using poly (butanediol succinate) (PBS), a biodegradable polymer, as carbon source and biofilm support. NO(3)-N concentration was determined by UV spectrophotometer. NO(2)-N concentration was assayed by hydrochloric acid naphthyl ethylenediamine spectrophotometry method. Total organic carbon (TOC) was measured using a TOC analyzer. The morphology of the samples was observed using an environmental scanning electron microscope (ESEM). The microbial community was analyzed by pyrosequencing method. The experimental results showed that an average removal efficiency of nitrate was 95 %. ESEM observation and FTIR analysis indicated the changes of PBS granules before and after microbial utilization. Pyrosequencing results showed that Betaproteobacteria predominated, and most of PBS-degrading denitrifying bacteria were assigned to the family Comamonadaceae. Denitrifying bacteria accounted for 13.02 % in total population. The PBS granules were suitable support and carbon source for denitrifying bacteria. PMID:22562343

  19. Biological removal of carbon disulfide from waste air streams

    SciTech Connect

    Hugler, W.; Acosta, C.; Revah, S.

    1999-09-30

    A pilot-scale biological control system for the treatment of 3,400 m{sup 3} h{sup {minus}1} of a gaseous stream containing up to 7.8 g CS{sub 2} m{sup {minus}3} and trace amounts of hydrogen sulfide (H{sub 2}S) was installed in a cellulose sponge manufacturing facility. The objective was to demonstrate the capability of the process to attain sustained removal efficiencies of 90% for CS{sub 2} and 99% for H{sub 2}S. The system consisted of two sequential biotrickling reactors, which had been previously inoculated with an adapted microbial consortium. During the pilot test, stable removal efficiency and elimination capacity of +90% and 220g CS{sub 2} m{sup {minus}3} h{sup {minus}1}, respectively, were attained with an empty bed residence time (EBTR) of 33 seconds for a period of several weeks. Efficiencies greater than 99% were always obtained for H{sub 2}S. Based on the results, the system was determined to be an effective process to remediate waste air streams containing reduced sulfur compounds generated at cellulose sponge facilities.

  20. Sources of carbon in inclusion bearing diamonds

    NASA Astrophysics Data System (ADS)

    Stachel, Thomas; Harris, Jeff W.; Muehlenbachs, Karlis

    2009-11-01

    The carbon isotopic composition ( δ13C) of diamonds containing peridotitic, eclogitic, websteritic and ultra-deep inclusions is re-evaluated on a detailed level. Applying a binning interval of 0.25‰, the previously recognized mode of peridotitic and eclogitic diamonds at about - 5‰ is shown to reflect at least two subpopulations with abundance peaks at ˜ - 5.75 to - 4.75‰ and ˜ - 4.50 to - 3.50‰. Within the peridotitic suite, diamonds with lherzolitic inclusions overall show higher δ13C values. Evolution away from a δ13C value of ˜ - 5‰, towards both 13C depleted and enriched compositions, is accompanied by decreasing maximum nitrogen contents of peridotitic diamonds. In combination with data on diamonds synthesized under reducing (metal melts) and more oxidizing conditions (carbonate-silicate interactions), this is taken to indicate that nitrogen is a compatible element in diamond that becomes depleted in the growth medium during progressive diamond precipitation. The observed co-variations of nitrogen content and δ13C around - 5‰ can then be modelled as reflecting closed system Rayleigh fractionation during crystallization of diamond from fluids/melts that are both reducing (i.e. methane bearing; evolution from ˜ - 5 to - 10‰) and oxidizing (i.e. CO 32- bearing; evolution from starting points varying between ˜ - 9 to - 5‰ and extending to about 0‰). Lherzolitic diamonds are believed to be mainly derived from diamond forming events subsequent to precipitation of predominantly Mesoarchean harzburgitic diamonds. The shift of lherzolitic diamonds towards higher δ13C values thus may relate to a temporal evolution, with carbonate bearing fluids with an initial isotopic composition ranging between about - 5.5 and - 1.5‰, derived from subducting oceanic crust, becoming increasingly important subsequent to the Mesoarchean. Devolatilization of marine carbonates ( δ13C ˜ 0‰) drives their isotopic composition towards mantle like values and

  1. Copper ions removal from water using functionalized carbon nanotubes–mullite composite as adsorbent

    SciTech Connect

    Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj

    2015-08-15

    Highlights: • CNTs–mullite composite was prepared via chemical vapor deposition (CVD) method. • The prepared composite was modified with concentrated nitric acid and chitosan. • The modified CNTs–mullite composites were used as novel adsorbents. • Copper ion removal from water by the prepared adsorbents was performed. • Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. - Abstract: Carbon nanotubes–mullite composite was synthesized by direct growth of carbon nanotubes on mullite particles via chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively. The carbon nanotubes–mullite composite was oxidized with concentrated nitric acid and functionalized with chitosan and then used as a novel adsorbent for copper ions removal from water. The results demonstrated that modification with concentrated nitric acid and chitosan improves copper ions adsorption capacity of the prepared composite, significantly. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. The carbon nanotubes growth on mullite particles to form the carbon nanotubes–mullite composite with further modification is an inherently safe approach for many promising environmental applications to avoid some concerns regarding environment, health and safety. It was found that the modified carbon nanotubes–mullite composite can be considered as an excellent adsorbent for copper ions removal from water.

  2. Mechanistic investigation of industrial wastewater naphthenic acids removal using granular activated carbon (GAC) biofilm based processes.

    PubMed

    Islam, Md Shahinoor; Zhang, Yanyan; McPhedran, Kerry N; Liu, Yang; Gamal El-Din, Mohamed

    2016-01-15

    Naphthenic acids (NAs) found in oil sands process-affected waters (OSPW) have known environmental toxicity and are resistant to conventional wastewater treatments. The granular activated carbon (GAC) biofilm treatment process has been shown to effectively treat OSPW NAs via combined adsorption/biodegradation processes despite the lack of research investigating their individual contributions. Presently, the NAs removals due to the individual processes of adsorption and biodegradation in OSPW bioreactors were determined using sodium azide to inhibit biodegradation. For raw OSPW, after 28 days biodegradation and adsorption contributed 14% and 63% of NA removal, respectively. For ozonated OSPW, biodegradation removed 18% of NAs while adsorption reduced NAs by 73%. Microbial community 454-pyrosequencing of bioreactor matrices indicated the importance of biodegradation given the diverse carbon degrading families including Acidobacteriaceae, Ectothiorhodospiraceae, and Comamonadaceae. Overall, results highlight the ability to determine specific processes of NAs removals in the combined treatment process in the presence of diverse bacteria metabolic groups found in GAC bioreactors. PMID:26410699

  3. AGRICULTURAL CONTAMINANTS REMOVAL FROM GROUNDWATER BY CARBON AND REVERSE OSMOSIS

    EPA Science Inventory

    The groundwater of Suffolk County, New York, is designated as a sole source aquifer and in recent years there have been increasing concerns about the contamination of this water by agricultural chemicals. Two parallel treatment systems were evaluated for a one-year period: granul...

  4. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO.

    PubMed

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. PMID:27245319

  5. International Space Station Carbon Dioxide Removal Assembly (ISS CDRA) Concepts and Advancements

    NASA Technical Reports Server (NTRS)

    ElSherif, Dina; Knox, James C.

    2005-01-01

    An important aspect of air revitalization for life support in spacecraft is the removal of carbon dioxide from cabin air. Several types of carbon dioxide removal systems are in use in spacecraft life support. These systems rely on various removal techniques that employ different architectures and media for scrubbing CO2, such as permeable membranes, liquid amine, adsorbents, and absorbents. Sorbent systems have been used since the first manned missions. The current state of key technology is the existing International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA), a system that selectively removes carbon dioxide from the cabin atmosphere. The CDRA system was launched aboard UF-2 in February 2001 and resides in the U.S. Destiny Laboratory module. During the past four years, the CDRA system has operated with varying degrees of success. There have been several approaches to troubleshooting the CDRA system aimed at developing work-around solutions that would minimize the impact on astronaut time required to implement interim solutions. The paper discusses some of the short-term fixes applied to promote hardware life and restore functionality, as well as long-term plans and solutions for improving operability and reliability. The CDRA is a critical piece of life support equipment in the air revitalization system of the ISS, and is demonstrated technology that may ultimately prove well-suited for use in lunar or Mars base, and Mars transit life support applications.

  6. Role of the surface chemistry of activated carbons in dye removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhou, Hua-lei; Zhen, Wen-juan; Zhu, Qian; Wu, Xiao-bin; Chang, Zhi-dong; Li, Wen-jun

    2015-07-01

    Commercial activated carbons were modified by a series of chemical or physical treatments using H2O2, NH3, and heating under N2 flow without notably changing their pore structures. The resultant carbons were characterized by N2 adsorption and Bohem titration and then used to remove Ponceau 4R, methyl orange and brilliant blue from aqueous solutions. Surface chemistry was found to play a significantly different role in removing these three compounds. The removal of anionic Ponceau 4R increases with increasing carbon surface basicity due to the predominant dispersive interaction mechanism. In contrast, surface chemistry has little effect on the removal of anionic methyl orange, which can be explained by two parallel mechanisms involving electrostatic and dispersive interactions due to the basic amine group in a dye molecule. The influence of surface chemistry on the removal of amphoteric brilliant blue dye can also be ignored due to a weak interaction between the carbons and dye molecules, which is resulted from strong cohesive energy from electrostatic forces inside amphoteric dye molecules.

  7. Source of silicate and carbonate cements during deep burial diagenesis

    SciTech Connect

    Dutta, P.K.

    1986-05-01

    Detrital silicate minerals and silicate cements (formed during shallow burial) of siliciclastic sandstones commonly dissolve during deep burial diagenesis. Quartz, feldspars, mica, and garnet among detrital silicate minerals, and quartz and kaolinite among authigenic silicate minerals show extensive dissolution features during deep burial diagenesis of siliciclastic sandstones of the Gondwana Supergroup, India. No dissolution features were observed in zircon, tourmalene, and rutile among detrital minerals or in chlorite and smectite among early formed authigenic minerals. Dissolution enriched the pore fluids in silica, potassium, sodium, calcium, magnesium, iron, and aluminum. Authigenic cements formed during this stage are illite, quartz, feldspar, iron oxide, and carbonates of calcium, magnesium, and iron. Mass-balance calculations show that the source of all silicate cements formed during deep burial diagenesis was internally derived from the dissolution of both detrital and early formed authigenic cements. However, a considerable gap exists between the amounts of cations (calcium, magnesium, and iron) derived internally and the respective amounts of these cations needed to form the various carbonate cements at this stage. Therefore, an outside source for these cations is needed to explain the formation of carbonate cements. A large mass transfer of cations from outside the sediment source seems remote since ground-water movement, which probably carried cement from an external source, is extremely restricted at great burial depths. Therefore, carbonate cements may have been major constituents during shallow burial diagenesis in Gondwana sandstones. Subsequently, these early formed carbonates were completely dissolved and remobilized as late-stage carbonate cement.

  8. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO

    NASA Astrophysics Data System (ADS)

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability.With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. Electronic supplementary information

  9. Metal Ion Removal from Wastewaters by Sorption on Activated Carbon, Cement Kiln Dust, and Sawdust.

    PubMed

    Shaheen, Sabry M; Eissa, Fawzy I; Ghanem, Khaled M; El-Din, Hala M Gamal; Al Anany, Fathia S

    2015-06-01

    This study assessed the efficiency of activated carbon, cement kiln dust (CKD), and sawdust for the removal of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) from aqueous solutions under mono-metal and competitive sorption systems and the removal of Cd, Cu, and Zn from different industrial wastewaters. Batch equilibrium experiments were conducted in a mono-metal and competitive sorption system. The efficiency of the sorbents in the removal of Cd, Cu, and Zn from industrial wastewaters was also investigated. Cement kiln dust expressed the highest affinity for the metals followed by activated carbon and sawdust. Competition among the metals changed their distribution coefficient (Kd) with the sorbents. Sorption of Pb and Cu was higher than Cd and Zn. The average metal removal from the wastewaters varied from 74, 61, and 60% for Cd, Cu, and Zn, respectively, to nearly 100%. The efficiencies of CKD and activated carbon in removing metals were higher than sawdust, suggesting their potential as low-cost sorbents for the removal of toxic metals from wastewaters. PMID:26459819

  10. Removal of cadmium ion from wastewater by carbon-based nanosorbents: a review.

    PubMed

    Kumar, Rajeev; Chawla, Jyoti; Kaur, Inderpreet

    2015-03-01

    A green environment and a healthy life are dream projects of today's science and technology to save the world. Heavy metal ions in water affect both environment and human health. Cadmium has been identified as one of the heavy metals that causes acute or chronic toxic effects if ingested. Increasing use of cadmium in different technological fields has raised concern about its presence and removal from water/wastewater. Researchers have made many systematic efforts to remove heavy metals from water to reduce their impact on human beings and the environment. Adsorption is one of the best methods to remove heavy metals from water among the different proposed methods. This study explores carbon-based nanosorbents which have been proved as effective adsorbents for removal of cadmium ions from water. The adsorption efficiency of carbon-based nanosorbents is the main criterion to rank and select them for removal of cadmium ions from water. Toxicity, reusability and environmentally friendly characteristics of sorbents are also taken considered while ranking the suitable carbon-based nanosorbents for removal of cadmium ions from water. PMID:25719462

  11. Removal of sulfur compounds from petroleum refinery wastewater through adsorption on modified activated carbon.

    PubMed

    Ben Hariz, Ichrak; Al Ayni, Foued; Monser, Lotfi

    2014-01-01

    The adsorption of sulfur compounds from petroleum refinery wastewater on a chemically modified activated carbon (MAC) was investigated. The modification technique (nitric acid, hydrogen peroxide and thermal modification) enhanced the removal capacity of carbon and therefore decreases cost-effective removal of sulfide from refinery wastewater. Adsorption equilibrium and kinetics data were determined for sulfur removal from real refinery wastewater. The data were evaluated according to several adsorption isotherm and kinetics models. The Freundlich isotherm fitted well with the equilibrium data of sulfur on different adsorbents, whereas the kinetics data were best fitted by the pseudo-second-order model. Insights of sulfide removal mechanisms indicated that the sorption was controlled through the intraparticle diffusion mechanism with a significant contribution of film diffusion. The MAC adsorbent was found to have an effective removal capacity of approximately 2.5 times that of non-modified carbon. Using different MAC, sulfides were eliminated with a removal capacity of 52 mg g(-1). Therefore, MAC can be utilized as an effective and less expensive adsorbent for the reduction of sulfur in refinery wastewater. PMID:25353943

  12. Preparation of Bamboo Chars and Bamboo Activated Carbons to Remove Color and COD from Ink Wastewater.

    PubMed

    Hata, Motohide; Amano, Yoshimasa; Thiravetyan, Paitip; Machida, Motoi

    2016-01-01

    Bamboo chars and bamboo activated carbons prepared by steam activation were applied for ink wastewater treatment. Bamboo char at 800 °C was the best for the removal of color and chemical oxygen demand (COD) from ink wastewater compared to bamboo chars at 300 to 700 °C due to higher surface area and mesopore volume. Bamboo activated carbon at 600 °C (S600) was the best compared to bamboo activated carbon at 800 °C (S800), although S800 had larger surface area (1108 m(2)/g) than S600 (734 m(2)/g). S600 had higher mesopore volume (0.20 cm(3)/g) than S800 (0.16 cm(3)/g) and therefore achieved higher color and COD removal. All bamboo activated carbons showed higher color and COD removal efficiency than commercial activated carbon. In addition, S600 had the superior adsorption capacity for methylene blue (0.89 mmol/g). Therefore, bamboo is a suitable material to prepare adsorbents for removal of organic pollutants. PMID:26803031

  13. Modulation of Candida albicans Biofilm by Different Carbon Sources.

    PubMed

    Pemmaraju, Suma C; Pruthi, Parul A; Prasad, R; Pruthi, Vikas

    2016-06-01

    In the present investigation, the role of carbon sources (glucose, lactate, sucrose, and arabinose) on Candida albicans biofilm development and virulence factors was studied on polystyrene microtiter plates. Besides this, structural changes in cell wall component β-glucan in presence of different carbon sources have also been highlighted. Biofilm formation was analyzed by XTT (2,3-bis[2-Methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay. Glucose-grown cells exhibited the highest metabolic activity during adhesion among all carbon sources tested (p < 0.05). However, cells exposed to sucrose exhibited highest biofilm formation and matrix polysaccharides secretion after 48 h. The results also correlated with the biofilm height and roughness measurements by atomic force microscopy. Exposure to lactate induced hyphal structures with the highest proteinase activity while arabinose-grown cells formed pseudohyphal structures possessing the highest phospholipase activity. Structural changes in β-glucan characterized by Fourier transform infrared (FTIR) spectroscopy displayed characteristic band of β-glucan at 892 cm(-1) in all carbon sources tested. The β(1→6) to β(1→3) glucan ratio calculated as per the band area of the peak was less in lactate (1.15) as compared to glucose (1.73), sucrose (1.62), and arabinose (2.85). These results signify that carbon sources influence C. albicans biofilm development and modulate virulence factors and structural organization of cell wall component β-glucan. PMID:26899861

  14. Denitrification of high nitrate concentration wastewater using alternative carbon sources.

    PubMed

    Fernández-Nava, Y; Marañón, E; Soons, J; Castrillón, L

    2010-01-15

    The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar-rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO(3)-N/g VSS h were obtained. The effluents were nitrate-free and very low COD concentrations were obtained in 4-6h reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS(formed)/g NO(x)-N(reduced)). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5-6.5 for the sugar-rich carbon sources. PMID:19782470

  15. Treating vacuum-carbonate sulfur removal wastewater by electrochemical methods

    SciTech Connect

    Kovalenko, V.S.; Levi, E.V.; Panasenko, L.A.

    1982-11-06

    The feasibility of treating coke plant waste water which has been desulfurized by the vacuum-carbonate process, by electrochemical methods has been studied in the laboratory. Model systems (potassium formate, potassium ferrocyanide, potassium thiocyanate, potassium thiosulfate) and coke plant wash liquor were electrolyzed using four steel cathodes and 3 anodes (graphite, steel, and nickel); titanium-ruthenium oxide or manganese oxide; lead oxide on a titanium base with a ruthenium sublayer. Products for the model media were respectively, CO/sub 2/(K/sub 2/CO/sub 3/)/H/sub 2/; K/sub 3/Fe(CN)/sub 6/(Fe/sup +3/(Fe(OH)/sub 3/) + CNO/sup -/(N/sub 2/,NH/sub 4/ + CO/sub 2/, K/sub 2/CO/sub 3/))/H/sub 2/; SO/sub 4//sup -2/; CNO/sup -/ + H/sup +/ and CN/sup -/ + H/sub 2/S + H/sup +/; H/sub 2/S + OH (cathode) + SO/sub 4/ + H/sup +/ (anode). Electrolysis of plant waste water produced a decrease in alkalinity, sulfates, carbonates and bicarbonates. Minor amounts of gaseous materials (H/sub 2/S, CO, CO/sub 2/) and prussic acid are produced and should be discharged to the coke oven gas system. The process is efficient, cost effective, requires low cost engineering and provides recyclable wash liquor. Due to their high initial concentration, decomposition of thiocyanates determines the time for full neutraliztion of the waste water. Graphite is the best anode material.

  16. Methods and compositions for removing carbon dioxide from a gaseous mixture

    SciTech Connect

    Li, Jing; Wu, Haohan

    2014-06-24

    Provided is a method for adsorbing or separating carbon dioxide from a mixture of gases by passing the gas mixture through a porous three-dimensional polymeric coordination compound having a plurality of layers of two-dimensional arrays of repeating structural units, which results in a lower carbon dioxide content in the gas mixture. Thus, this invention provides useful compositions and methods for removal of greenhouse gases, in particular CO.sub.2, from industrial flue gases or from the atmosphere.

  17. A 1-D Model of the 4 Bed Molecular Sieve of the Carbon Dioxide Removal Assembly

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, Jim

    2015-01-01

    Developments to improve system efficiency and reliability for water and carbon dioxide separation systems on crewed vehicles combine sub-scale systems testing and multi-physics simulations. This paper describes the development of COMSOL simulations in support of the Life Support Systems (LSS) project within NASA's Advanced Exploration Systems (AES) program. Specifically, we model the 4 Bed Molecular Sieve (4BMS) of the Carbon Dioxide Removal Assembly (CDRA) operating on the International Space Station (ISS).

  18. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Astrophysics Data System (ADS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-07-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  19. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Technical Reports Server (NTRS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-01-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  20. Brines as Possible Cation Sources for Biomimetic Carbon Dioxide Sequestration

    NASA Astrophysics Data System (ADS)

    Bond, G. M.; Abel, A.; McPherson, B. J.; Stringer, J.

    2002-12-01

    The utility industry is currently producing 2.1 x 109 tonnes of CO2 per year from burning coal. The amounts of CO2 produced by a single coal-burning station are typically around 0.1 tonnes/MW/h for a coal burn of 0.04 tonnes/MW/h. These large fixed sources of CO2 constitute an obvious target for carbon sequestration to minimize greenhouse-gas emissions. The generally favored approach in present sequestration research is to achieve a CO2 stream that is highly concentrated, compress it, and transport it to geologic sequestration sites, such as deep saline aquifers. The volume of the CO2 is of some interest here. Supercritical CO2, as supplied for example from natural wells to enhanced oil recovery (EOR) sites, has a density of approximately 0.9, and is relatively incompressible, which means that the volume of sequestered supercritical CO2 will be somewhat greater than that of the coal from which it was formed. The volume of water displaced by CO2 injection into aquifers would be closely comparable to the volume of the CO2 itself. An alternative path, which we have been following, would capture the gas as calcium carbonate, CaCO3, in a biomimetic approach that offers some obvious advantages. Sequestration, in this case, is in the form of a safe, stable, environmentally benign product. On a geologic timeframe, considerable amounts of CO2 have been sequestered as, for example, oolitic limestone deposits and dolomite deposits, suggesting that very long-lived or even permanent sequestration is possible in solid carbonate form. Not only would our approach remove the costly steps of concentrating and compressing the CO2, but also it is anticipated that it would remove the need for long-term monitoring to check for CO2 leakage. In a separate collaborative study detailed by Abel and others (this volume), ramifications of geologic sequestration of CO2 and/or bicarbonate-enriched brines are evaluated with laboratory flow experiments and computer model simulations. Porosity and

  1. IMPROVING SOURCE PROFILES AND APPORTIONMENT OF COMBUSTION SOURCES USING THERMAL CARBON FRACTIONS IN MULTIVARIATE RECEPTOR MODELS

    EPA Science Inventory

    The purpose of this study was to improve combustion source profiles and apportionment of a PM2.5 urban aerosol by using 7 individual organic and elemental carbon thermal fractions in place of total organic and elemental carbon. This study used 3 years (96-99) of speciated data...

  2. Model-based diagnosis of a carbon dioxide removal assembly

    NASA Astrophysics Data System (ADS)

    Throop, David R.; Scarl, Ethan A.

    1992-03-01

    Model-based diagnosis (MBD) has been applied to a variety of mechanisms, but few of these have been in fluid flow domains. Important mechanism variables in these domains are continuous, and the mechanisms commonly contain complex recycle patterns. These properties violate some of the common assumptions for MBD. The CO2 removal assembly (CDRA) for the cabin atmosphere aboard NASA's Space Station Freedom is such a mechanism. Early work on diagnosing similar mechanisms showed that purely associative diagnostic systems could not adequately handle these mechanisms' frequent reconfigurations. This suggested a model-based approach and KATE was adapted to the domain. KATE is a constraint-based MBD shell. It has been successfully applied to liquid flow problems in handling liquid oxygen. However, that domain does not involve complex recycle streams, but the CDRA does. KATE had solved constraint sets by propagating parameter values through constraints; this method often fails on constraints sets which describe recycle systems. KATE was therefore extended to allow it to use external algebraic programs to solve its constraint sets. This paper describes the representational challenges involved in that extension, and describes adaptions which allowed KATE to work within the representational limitations imposed by those algebraic programs. It also presents preliminary results of the CDRA modeling.

  3. Removal of Technetium, Carbon Tetrachloride, and Metals from DOE Properties

    SciTech Connect

    Mallouk, Thomas E.; Darab, John G.

    1999-06-01

    The objective of this research is to prepare, characterize, and evaluate new materials for the removal of technetium (Tc) compounds, halogenated organics, and other troublesome metals from DOE waste streams and contaminated areas. This work follows the discovery that a nanoscale form of zero-valent iron, dispersed on high surface area supports, reduces metal ions (Cr, Hg, Pb, Cd) and Re (as a surrogate for Tc) to insoluble forms much faster than does unsupported iron. The scientific goals of the project are to better understand the mechanism of the reduction process, to develop supports that are compatible with a variety of mixed waste compositions, and to develop surface modifiers for supported iron that will optimize selectivity for the contaminants of interest. The support composition is of particular interest in the case of Tc separation and stabilization in the Hanford tank wastes. While tests with tank waste simulants have shown that pertechnetate is reduced insoluble TcO2, the support material must be compatible with the vitrification process used in the final waste disposition. The surface modifications are also a focal point for Hanford applications because of the complex and variable makeup of the tank wastes.

  4. Implications of biocrust removal on soil organic carbon losses by water erosion in a badlands area

    NASA Astrophysics Data System (ADS)

    Chamizo, Sonia; Raúl Román, José; Miralles, Isabel; Rodríguez-Caballero, Emilio; Cantón, Yolanda

    2015-04-01

    In arid and semiarid ecosystems, soils are characterized by having low organic carbon (OC) content and low fertility. In these systems, runoff, often generated in interplant soils, plays a crucial role in OC redistribution from source (interplant) areas to sink (vegetation) patches. Far from being bare, interplant soils in most arid and semiarid ecosystems are commonly covered by communities of cyanobacteria, algae, lichens and mosses, known as biocrusts, which may reach up to 80% of soil cover. Biocrusts fix atmospheric C and increase the soil OC pool by several folds respect bare soils. In addition, biocrusts form a film on the surface that strongly protects soils against water erosion and prevents from OC losses. However, the role of BSCs in reducing OC losses associated to runoff and erosion may depend on the type and development of biocrust. On the other hand, loss of BSCs provoked by frequent disturbances in arid and semiarid areas leads to an increase in runoff and erosion, which may have important effects on OC losses and nutrient impoverishment in interplant areas. Despite their recognized role, very few studies have explicitly evaluated OC losses from runoff and erosion in soils covered by different types of biocrusts and, more importantly, the effects of biocrust disturbance on OC losses. The aim of this study was to analyse the influence of two biocrust types (cyanobacteria and lichens) as well as of biocrust removal on dissolved and sediment OC losses, in a badlands site of southeastern Spain. Runoff and erosion after rain were measured in small field plots (1 m2) during one hydrological year and water samples collected for determination of dissolved OC and OC bonded to sediments. Our results showed that total OC losses decreased with biocrust development and that biocrust removal caused a dramatic increase in OC losses. The first rain after biocrust removal contributed the most to OC losses as runoff and, more noticeable, erosion greatly increased

  5. Development of a carbon filter system for removing malachite green from hatchery effluents

    SciTech Connect

    Marking, L.L. ); Leith, D. ); Davis, J. )

    1990-04-01

    The US Fish and Wildlife Service was granted an investigational New Animal Drug permit by the US Food and Drug Administration for the use of malachite green as a fungicide at selected state and federal fish hatcheries. However, the permit required that the fungicide be removed from all treated water after March 1989. A study was designed to (1) determine the type of filter and kind of carbon that was most efficient for removal of malachite green and (2) demonstrate that carbon filters can be used to remove malachite green from water used for egg incubation or to hold adult salmon before spawning. Minicolumn simulation studies showed that 8 {times} 30-mesh granular carbon was effective for continuously removing malachite green from water for 230 d at a flow rate of 500 gal/min and for only 62 d at a flow rate of 1,000 gal/min. The removal capacity at the slower flow rate was 1.1 oz of malachite green per pound of carbon. A filter system that contained 20,000 lb of activated carbon in each of two chambers was effective for removal of malachite green from treated water in adult salmon holding ponds at flows of 500 gal/min (6.4 gal/min per ft{sup 2}) and greater. The removal efficiency was 99.8% after 105 h of operation, and the adsorption capacity of the system was projected to be sufficient for 20 or more years of routine hatchery operation. A filter system that contained 2,000 lb of activated carbon in each of two chambers was effective for removal of malachite green from treated water in salmon egg incubation units at the designated flow rate of 50 gal/min (4.0 gal/min per ft{sup 2}) and also at faster flow rates. Removal efficiency decreased only slightly for faster flows in both filter systems, and the efficiency improved when treated water was passed through two filter chambers in series.

  6. RELATIONSHIP BETWEEN MASS FLUX REDUCTION AND SOURCE-ZONE MASS REMOVAL: ANALYSIS OF FIELD DATA

    PubMed Central

    DiFilippo, Erica L.

    2010-01-01

    The magnitude of contaminant mass flux reduction associated with a specific amount of contaminant mass removed is a key consideration for evaluating the effectiveness of a source-zone remediation effort. Thus, there is great interest in characterizing, estimating, and predicting relationships between mass flux reduction and mass removal. Published data collected for several field studies were examined to evaluate relationships between mass flux reduction and source-zone mass removal. The studies analyzed herein represent a variety of source-zone architectures, immiscible-liquid compositions, and implemented remediation technologies. There are two general approaches to characterizing the mass-flux-reduction/mass-removal relationship, end-point analysis and time-continuous analysis. End-point analysis, based on comparing masses and mass fluxes measured before and after a source-zone remediation effort, was conducted for 21 remediation projects. Mass removals were greater than 60% for all but three of the studies. Mass flux reductions ranging from slightly less than to slightly greater than one-to-one were observed for the majority of the sites. However, these single-snapshot characterizations are limited in that the antecedent behavior is indeterminate. Time-continuous analysis, based on continuous monitoring of mass removal and mass flux, was performed for two sites, both for which data were obtained under water-flushing conditions. The reductions in mass flux were significantly different for the two sites (90% vs. ~8%) for similar mass removals (~40%). These results illustrate the dependence of the mass-flux-reduction/mass-removal relationship on source-zone architecture and associated mass-transfer processes. Minimal mass flux reduction was observed for a system wherein mass removal was relatively efficient (ideal mass transfer and displacement). Conversely, a significant degree of mass flux reduction was observed for a site wherein mass removal was inefficient

  7. Production of polyhydroxyalkanoates (PHAs) with canola oil as carbon source.

    PubMed

    López-Cuellar, M R; Alba-Flores, J; Rodríguez, J N Gracida; Pérez-Guevara, F

    2011-01-01

    Wautersia eutropha was able to synthesize medium chain length polyhydroxyalkanoates (PHAs) when canola oil was used as carbon source. W. eutropha was cultivated using fructose and ammonium sulphate as carbon and nitrogen sources, respectively, for growth and inoculum development. The experiments were done in a laboratory scale bioreactor in three stages. Initially, the biomass was adapted in a batch culture. Secondly, a fed-batch was used to increase the cell dry weight and PHA concentration to 4.36 g L(-1) and 0.36 g L(-1), respectively. Finally, after the addition of canola oil as carbon source a final concentration of 18.27 g L(-1) PHA was obtained after 40 h of fermentation. With canola oil as carbon source, the polymer content of the cell dry matter was 90%. The polymer was purified from dried cells and analyzed by FTIR, NMR and DSC using PHB as reference. The polymer produced by W. eutropha from canola oil had four carbon monomers in the structure of the PHA and identified by 1H and 13C NMR analysis as 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxyoctanoate (3HO), and 3-hydroxydodecanoate (3HDD). PMID:20933541

  8. Laser Patterning of Diamond. Part II. Surface Nondiamond Carbon Formation and its Removal

    SciTech Connect

    Smedley, J.; Jaye, C; Bohon, J; Rao, T; Fischer, D

    2009-01-01

    As diamond becomes more prevalent for electronic and research applications, methods of patterning diamond will be required. One such method, laser ablation, has been investigated in a related work. We report on the formation of surface nondiamond carbon during laser ablation of both polycrystalline and single-crystal synthetic diamonds. Near edge x-ray absorption fine structure spectroscopy was used to confirm that the nondiamond carbon layer formed during the ablation was amorphous, and Fourier transform infrared absorption spectroscopy (FTIR) was used to estimate the thickness of this layer to be {approx} 60 nm. Ozone cleaning was used to remove the nondiamond carbon layer.

  9. Black carbon and carbon monoxide over Bay of Bengal during W_ICARB: Source characteristics

    NASA Astrophysics Data System (ADS)

    Girach, I. A.; Nair, Vijayakumar S.; Babu, S. Suresh; Nair, Prabha R.

    2014-09-01

    The ship borne measurements of near-surface black carbon (BC) and carbon monoxide (CO) were carried out over Bay of Bengal (BoB) during the winter period of 2009 under W_ICARB, the second phase of ‘Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)'. The CO mixing ratio and BC mass concentration varied in the ranges of 80-480 ppbv and 75-10,000 ng m-3, respectively over this marine region. The BC and CO showed similar variations over northern BoB where airmass from Indo-Gangetic Plain (IGP) region prevailed during the observations period leading to a very strong positive correlation. The association of BC and CO was poor over the eastern and southern part of BoB could be due to the removal of BC aerosols by rain and/or processes of dilution and mixing while transported over to BoB. The highest value of CO observed over eastern BoB was partially due to biomass burning over East Asia. The BC/CO ratio for IGP airmass found to be 20.3 ng m-3 ppb-1 and ∼16 ng m-3 ppb-1 during winter and pre-monsoon, respectively which indicate the role of biomass burning as the source of BC over the region. Based on the emission flux of CO from various inventories and observed BC/CO ratios during pre-monsoon and winter, the BC emission for India is estimated to be in the range of 0.78-1.23 Tg year-1. The analysis of scavenging of BC revealed the loss rate of BC due to relative humidity 0.39 ± 0.08 ng m-3 ppb-1 RH (%)-1 over northern BoB and 0.53 ± 0.04 ng m-3 ppb-1 RH (%)-1 over the southern-BoB during winter.

  10. Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation.

    PubMed

    Beurskens, Charlotte J; Brevoord, Daniel; Lagrand, Wim K; van den Bergh, Walter M; Vroom, Margreeth B; Preckel, Benedikt; Horn, Janneke; Juffermans, Nicole P

    2014-01-01

    Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO2) diffusion capacity. This allows lower driving pressures in mechanical ventilation and increased CO2 diffusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes. Methods. This is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted after a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A fixed protective ventilation protocol (6 mL/kg) was used, with prospective observation for changes in lung mechanics and gas exchange. Statistics was by Bonferroni post-hoc correction with statistical significance set at P < 0.017. Results. During heliox ventilation, respiratory rate decreased (25 ± 4 versus 23 ± 5 breaths min(-1), P = 0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1 ± 1.9 versus 9.9 ± 2.1 L min(-1), P = 0.026), while reducing PaCO2 levels (5.0 ± 0.6 versus 4.5 ± 0.6 kPa, P = 0.011) and peak pressures (21.1 ± 3.3 versus 19.8 ± 3.2 cm H2O, P = 0.024). Conclusions. Heliox improved CO2 elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation. PMID:25548660

  11. Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation

    PubMed Central

    Beurskens, Charlotte J.; Brevoord, Daniel; Lagrand, Wim K.; van den Bergh, Walter M.; Vroom, Margreeth B.; Preckel, Benedikt; Horn, Janneke; Juffermans, Nicole P.

    2014-01-01

    Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO2) diffusion capacity. This allows lower driving pressures in mechanical ventilation and increased CO2 diffusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes. Methods. This is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted after a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A fixed protective ventilation protocol (6 mL/kg) was used, with prospective observation for changes in lung mechanics and gas exchange. Statistics was by Bonferroni post-hoc correction with statistical significance set at P < 0.017. Results. During heliox ventilation, respiratory rate decreased (25 ± 4 versus 23 ± 5 breaths min−1, P = 0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1 ± 1.9 versus 9.9 ± 2.1 L min−1, P = 0.026), while reducing PaCO2 levels (5.0 ± 0.6 versus 4.5 ± 0.6 kPa, P = 0.011) and peak pressures (21.1 ± 3.3 versus 19.8 ± 3.2 cm H2O, P = 0.024). Conclusions. Heliox improved CO2 elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation. PMID:25548660

  12. Production of biodiesel from carbon sources of macroalgae, Laminaria japonica.

    PubMed

    Xu, Xu; Kim, Ji Young; Oh, Yu Ri; Park, Jong Moon

    2014-10-01

    As aquatic biomass which is called "the third generation biomass", Laminaria japonica (also known as Saccharina japonica) consists of mannitol and alginate which are the main polysaccharides of algal carbohydrates. In this study, oleaginous yeast (Cryptococcus curvatus) was used to produce lipid from carbon sources derived from Laminaria japonica. Volatile fatty acids (VFAs) were produced by fermentation of alginate extracted from L. japonica. Thereafter, mannitol was mixed with VFAs to culture the oleaginous yeast. The highest lipid content was 48.30%. The composition of the fatty acids was similar to vegetable oils. This is the first confirmation of the feasibility of using macroalgae as a carbon source for biodiesel production. PMID:25084043

  13. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  14. Pd/RGO modified carbon felt cathode for electro-Fenton removing of EDTA-Ni.

    PubMed

    Zhang, Zhen; Zhang, Junya; Ye, Xiaokun; Hu, Yongyou; Chen, Yuancai

    2016-01-01

    Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel due to its strong chelation. The electro-Fenton (EF) process using a cathode made from palladium (Pd), reduced graphene oxide (RGO) and carbon felt, fed with air, exhibited high activities and stability for the removal of 10 mg L(-1) EDTA-Ni solution. Pd/RGO catalyst was prepared by one-pot synthesis; the scanning electron microscopy and X-ray diffraction analysis indicated nanoparticles and RGO were well distributed on carbon felt, forming three dimensional architecture with both large macropores and a mesoporous structure. The cyclic voltammetric results showed that the presence of RGO in Pd/RGO/carbon felt significantly increased the current response of two-electron reduction of O2 (0.45 V). The key factors influencing the removal efficiency of EDTA-Ni, such as pH, current and Fe(2+) concentration, were investigated. Under the optimum conditions, the removal efficiency of EDTA-Ni reached 83.8% after 100 min EF treatment. Mechanism analysis indicated that the introduction of RGO in Pd/RGO/carbon felt significantly enhanced the electrocatalytic activities by inducing •OH in the EF process; direct H2O2 oxidation still accounted for a large amount of EDTA-Ni removal efficiency. PMID:27508368

  15. Regenerable metallic oxide systems for removal of carbon dioxide: A concept

    NASA Technical Reports Server (NTRS)

    Sutton, J. G.; Heimlich, P. F.; Tepper, E. H.

    1972-01-01

    Design concepts for portable canisters for removal of carbon dioxide are described. One is screen pack configuration consisting of brazed rectangular canister with four metal oxide packs inserted. Other is radial flow canister with perforated central tube. Methods of production and operating principles are presented.

  16. Influence and efficiency of catalytic stripper in organic carbon removal from laboratory generated soot aerosols

    EPA Science Inventory

    A catalytic stripper (CS) is a device used to remove the semi-volatile, typically organic carbon, fraction by passing raw or diluted exhaust over an oxidation catalyst heated to 300˚C. The oxidation catalyst used in this study is a commercially available diesel oxidation ca...

  17. Residue removal and climatic effects on soil carbon content of no-till soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While no-till management practices usually result in increased soil organic carbon (SOC) contents, the effect of residue removal with no-till is not well understood, especially in warmer climates. A multi-year study was conducted at six locations having a wide range of climatic conditions in centra...

  18. Removal of anaerobic soluble microbial products in a biological activated carbon reactor.

    PubMed

    Dong, Xiaojing; Zhou, Weili; He, Shengbing

    2013-09-01

    The soluble microbial products (SMP) in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon (BAC) was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket (UASB) reactors. The high strength organics were degraded in the first UASB reactor (UASB1) and the second UASB (UASB2, i.e., BAC) functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand (COD) was 10,000 mg/L and the organic loading rate achieved 10 kg COD/(m3 x day), the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L. PMID:24520716

  19. Removal efficiencies for 136 tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofuran congeners with activated carbons.

    PubMed

    Zhou, Xu-Jian; Li, Xiao-Dong; Ni, Ming-Jiang; Cen, Ke-Fa

    2015-11-01

    In this study, the removal efficiency of 136 tetra- to octa-chlorinated dibenzo-p-dioxin (CDD)/furan (F) congeners from a nitrogen + oxygen carrier gas was studied using a laboratory-scale, fixed bed adsorption system. Two kinds of activated carbon with dissimilar pore structures were used as adsorbents. The total concentration of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) in the source gas was 541 ng/Nm(3) and that of the 17 toxic 2,3,7,8-substituted PCDD/Fs 96.35 ng/Nm(3), accounting for 17.8% of the total original weight amount. Their toxic equivalent quantity (TEQ) was 8.31 ng I-TEQ/Nm(3). For both activated carbons, the removal efficiencies of the ten PCDD/F homologue groups rise with chlorine substitution number. The removal efficiencies vary approximately as a power function of vapor pressure (correlation coefficients r(2) = 0.93 and 0.81, respectively). Competitive adsorption and desorption occur as adsorption time went on, causing elution of the lower chlorinated homologues, i.e. tetra-CDD/F and Penta-CDD/F congeners. In addition, there are significantly different concentration distributions for isomers in the same homologue groups. However, their removal efficiencies have weak correlation with their initial concentrations. The correlation coefficients are from -0.47 to 0.32 and from -0.57 to 0.46 respectively for the two kinds of activated carbons. PMID:26154037

  20. Arsenic removal from groundwater using low-cost carbon composite electrodes for capacitive deionization.

    PubMed

    Lee, Ju-Young; Chaimongkalayon, Nantanee; Lim, Jinho; Ha, Heung Yong; Moon, Seung-Hyeon

    2016-01-01

    Affordable carbon composite electrodes were developed to treat low-concentrated groundwater using capacitive deionization (CDI). A carbon slurry prepared using activated carbon powder (ACP), poly(vinylidene fluoride), and N-methyl-2-pyrrolidone was employed as a casting solution to soak in a low-cost porous substrate. The surface morphology of the carbon composite electrodes was investigated using a video microscope and scanning electron microscopy. The capacitance and electrical conductivity of the carbon composite electrodes were then examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. According to the CV and EIS measurements, the capacitances and electrical conductivities of the carbon composite electrodes were in the range of 8.35-63.41 F g(-1) and 0.298-0.401 S cm(-1), respectively, depending on ACP contents. A CDI cell was assembled with the carbon composite electrodes instead of with electrodes and current collectors. The arsenate removal test included an investigation of the optimization of several important operating parameters, such as applied voltage and solution pH, and it achieved 98.8% removal efficiency using a 1 mg L(-1) arsenate solution at a voltage of 2 V and under a pH 9 condition. PMID:27332854

  1. Removal of cationic heavy metal from aqueous solution by activated carbon impregnated with anionic surfactants.

    PubMed

    Ahn, Chi K; Park, Donghee; Woo, Seung H; Park, Jong M

    2009-05-30

    To increase their capacity to adsorb heavy metals, activated carbons were impregnated with the anionic surfactants sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), or dioctyl sulfosuccinate sodium (DSS). Surfactant-impregnated activated carbons removed Cd(II) at up to 0.198 mmol g(-1), which was more than an order of magnitude better than the Cd(II) removal performance of activated carbon without surfactant (i.e., 0.016 mmol g(-1)) even at optimal pH (i.e., pH 6). The capacity of the activated carbon to adsorb Cd(II) increased in proportion to the quantity of surfactant with which they were impregnated. The kinetics of the adsorption of Cd(II) onto the surfactant-impregnated activated carbon was best described by a pseudo-second-order model, and was described better by the Freundlich adsorption isotherm than by the Langmuir isotherm. The surface charge of activated carbon was negative in all pH ranges tested (2-6). These results indicate that surface modification with anionic surfactant could be used to significantly enhance the capacity of activated carbon to adsorb cations. PMID:19022570

  2. Maximising biohydrogen yields via continuous electrochemical hydrogen removal and carbon dioxide scrubbing.

    PubMed

    Massanet-Nicolau, Jaime; Jones, Rhys Jon; Guwy, Alan; Dinsdale, Richard; Premier, Giuliano; Mulder, Martijn J J

    2016-10-01

    The use of electrochemical hydrogen removal (EHR) together with carbon dioxide removal (CDR) was demonstrated for the first time using a continuous hydrogen producing fermenter. CDR alone was found to increase hydrogen yields from 0.07molH2molhexose to 0.72molH2molhexose. When CDR was combined with EHR, hydrogen yields increased further to 1.79molH2molhexose. The pattern of carbohydrate utilisation and volatile fatty acid (VFA) production are consistent with the hypothesis that increased yields are the result of relieving end product inhibition and inhibition of microbial hydrogen consumption. In situ removal of hydrogen and carbon dioxide as demonstrated here not only increase hydrogen yield but also produces a relatively pure product gas and unlike other approaches can be used to enhance conventional, mesophilic, CSTR type fermentation of low grade/high solids biomass. PMID:27394998

  3. Vinca Institute safety and licensing actions for carbon steel structure removal from RA research reactor SNF pool

    SciTech Connect

    Pesic, M.; Sotic, O.; Pavlovic, S.; Ljubenov, V.; Nikolic, A.

    2008-07-15

    Carbon steel structure, inserted in water of the spent nuclear fuel pool of the RA research reactor in 1960 for decontamination of primary cooling circuit components, was recognized as the main source of corrosion in the pool. Inappropriate water chemical parameters have initiated corrosion of aluminum cladding of spent fuel elements stored in aluminum barrels. It was confirmed by measuring of activity of {sup 137}Cs nuclide in the pool water samples. A complex project was developed with the IAEA assistance and R and D Company OEC NIKIMT (RF) to remove the carbon steel structure from the pool, since 2004. After long preparation process, including safety analysis of the operation and Serbian regulatory authority approval, the structure was removed, packed and stored at the Vinca radioactive waste storage from November 2006 to February 2007. This paper underlines major safety and licensing actions taken by the Vinca Institute to safely remove the structure and make a room in the pool basin for future spent nuclear fuel repackage operation. (author)

  4. Effects of activated carbon fibre-supported metal oxide characteristics on toluene removal.

    PubMed

    Liu, Zhen-Shu; Peng, Yu-Hui; Li, Wen-Kai

    2014-01-01

    Few studies have investigated the use of activated carbon fibres (ACFs) impregnated with metal oxides for the catalytic oxidation of volatile organic compounds (VOCs). Thus, the effects of the ACF-supported metal oxides on toluene removal are determined in this study. Three catalysts, namely, Ce, Mn, and Cu, two pretreatment solutions NaOH and H2O2, and three reaction temperatures of 250 degrees C, 300 degrees C, and 350 degrees C, were employed to determine toluene removal. The composition and morphology of the catalysts were analysed using Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectrometer (FTIR), and thermo-gravimetric analyser (TGA) to study the effects of the catalyst's characteristics on toluene removal. The results demonstrated that the metal catalysts supported on the ACFs could significantly increase toluene removal. The Mn/ACFs and Cu/ACFs were observed to be most active in toluene removal at a reaction temperature of 250 degrees C with 10% oxygen content. Moreover, the data also indicated that toluene removal was slightly improved after pretreating the ACFs with NaOH and H2O2. The results suggested that surface-metal loading and the surface characteristics of the ACFs were the determinant parameters for toluene removal. Furthermore, the removal of toluene over Mn/ACFs-H202 decreased when the reaction temperature considered was > 300 degrees C. PMID:24701949

  5. Selective Removal of Dental Composite using a Rapidly Scanned Carbon Dioxide Laser.

    PubMed

    Chan, Kenneth H; Fried, Daniel

    2011-01-01

    Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel. PMID:21927546

  6. Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process.

    PubMed

    Regmi, Pusker; Garcia Moscoso, Jose Luis; Kumar, Sandeep; Cao, Xiaoyan; Mao, Jingdong; Schafran, Gary

    2012-10-30

    Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g). PMID:22687632

  7. Selective removal of dental composite using a rapidly scanned carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    Dental restorative materials are color matched to the tooth and are difficult to remove by mechanical means without excessive removal or damage to peripheral enamel and dentin. Lasers are ideally suited for selective ablation to minimize healthy tissue loss when replacing existing restorations, sealants or removing composite adhesives such as residual composite left after debonding orthodontic brackets. In this study a carbon dioxide laser operating at high laser pulse repetition rates integrated with a galvanometer based scanner was used to selectively remove composite from tooth surfaces. A diode array spectrometer was used to measure the plume emission after each laser pulse and determine if the ablated material was tooth mineral or composite. The composite was placed on tooth buccal and occlusal surfaces and the carbon dioxide laser was scanned across the surface to selectively remove the composite without excessive damage to the underlying sound enamel. The residual composite and the damage to the underlying enamel was evaluated using optical microscopy. The laser was able to rapidly remove the composites rapidly from both surfaces with minimal damage to the underlying sound enamel.

  8. Source Separation of Urine as an Alternative Solution to Nutrient Management in Biological Nutrient Removal Treatment Plants.

    PubMed

    Jimenez, Jose; Bott, Charles; Love, Nancy; Bratby, John

    2015-12-01

    Municipal wastewater contains a mixture of brown (feces and toilet paper), yellow (urine), and gray (kitchen, bathroom and wash) waters. Urine contributes approximately 70-80% of the nitrogen (N), 50-70% of the phosphorus (P) load and 60-70% of the pharmaceutical residues in normal domestic sewage. This study evaluated the impact of different levels of source separation of urine on an existing biological nutrient removal (BNR) process. A process model of an existing biological nutrient removal (BNR) plant was used. Increasing the amount of urine diverted from the water reclamation facilities, has little impact on effluent ammonia (NH₃-N) concentration, but effluent nitrate (NO₃-N) concentration decreases. If nitrification is necessary then no reduction in the sludge age can be realized. However, a point is reached where the remaining influent nitrogen load matches the nitrogen requirements for biomass growth, and no residual nitrogen needs to be nitrified. That allows a significant reduction in sludge age, implying reduced process volume requirements. In situations where nitrification is required, lower effluent nitrate (NO₃-N) concentrations were realized due to both the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The external carbon requirement for denitrification decreases as the urine separation efficiency increases due to the lower influent nitrogen content in the wastewater and a more favorable nitrogen-to-carbon ratio for denitrification. The effluent phosphorus concentration decreases when the amount of urine sent to water reclamation facilities is decreased due to lower influent phosphorus concentrations. In the case of chemical phosphate removal, urine separation reduces the amount of chemicals required. PMID:26652123

  9. An innovative carbonate coprecipitation process for the removal of zinc and manganese from mining impacted waters

    USGS Publications Warehouse

    Sibrell, P.L.; Chambers, M.A.; Deaguero, A.L.; Wildeman, T.R.; Reisman, D.J.

    2007-01-01

    Although mine drainage is usually thought of as acidic, there are many cases where the water is of neutral pH, but still contains metal species that can be harmful to human or aquatic animal health, such as manganese (Mn) and zinc (Zn). Typical treatment of mine drainage waters involves pH adjustment, but this often results in excessive sludge formation and removal of nontoxic species such as magnesium and calcium. Theoretical consideration of the stability of metal carbonate species suggests that the target metals could be removed from solution by coprecipitation with calcium carbonate. The U.S. Geological Survey has developed a limestone-based process for remediation of acid mine drainage that increases calcium carbonate saturation. This treatment could then be coupled with carbonate coprecipitation as an innovative method for removal of toxic metals from circumneutral mine drainage waters. The new process was termed the carbonate coprecipitation (CCP) process. The CCP process was tested at the laboratory scale using a synthetic mine water containing 50 mg/L each of Mn and Zn. Best results showed over 95% removal of both Mn and Zn in less than 2 h of contact in a limestone channel. The process was then tested on a sample of water from the Palmerton zinc superfund site, near Palmerton, Pennsylvania, containing over 300 mg/L Zn and 60 mg/L Mn. Treatment of this water resulted in removal of over 95% of the Zn and 40% of the Mn in the limestone channel configuration. Because of the potential economic advantages of the CCP process, further research is recommended for refinement of the process for the Palmerton water and for application to other mining impacted waters as well. ?? Mary Ann Liebert, Inc.

  10. Carbon Dioxide Removal and Conversion to Ocean Alkalinity: Why and How

    NASA Astrophysics Data System (ADS)

    Rau, G. H.

    2014-12-01

    Drastic reduction in anthropogenic CO2 emissions is the most obvious way to stabilize atmospheric CO2. However, there is growing risk that effective emissions reduction policies and technologies will not engage soon enough to avoid significant CO2-induced climate and ocean acidification impacts. This realization has lead to increased interest (e.g., IPCC AR5, 2014; NRC/NAS, 2014) in the possibility of pro-actively increasing CO2 removal (CDR) from the atmosphere above the 55% of our emissions that are already removed from air by natural land and ocean processes. While a variety of biotic, abiotic, and hybrid CDR methods have been proposed, those involving geochemistry have much to recommend them. These methods employ the same geochemical reactions that naturally and effectively remove excess planetary CO2 and neutralize ocean acidity on geologic time scales. These reactions proceed when the hydrosphere, acidified by excess air CO2, contacts and reacts with carbonate and silicate minerals (>90% of the Earth's crust), producing dissolved bicarbonates and carbonates, i.e., ocean alkalinity. This alkalinity is eventually removed and the excess carbon stored via carbonate precipitation. So while the importance and global effectiveness of such reactions are not in question, it remains to be seen if this very slow, natural CDR could be safely and cost-effectively accelerated to help manage air CO2 levels on human rather than geologic time scales. Various terrestrial and marine, geochemistry-based CDR methods will be reviewed including: 1) the addition of minerals to soils and the ocean, 2) removal of CO2 from waste streams, esp. from biomass energy, via wet mineral contacting, and 3) the production and use of mineral derivatives, e.g. oxides or hydroxides, as CDR agents. The additional potential environmental benefits (e.g., reversal of ocean carbonate saturation loss) and impacts (e.g., increased mineral extraction), as well as potential economics will also be discussed.

  11. [Calculus removal efficiency and injury potential of vertically oscillating metallic and carbon ultrasonic tips].

    PubMed

    Naef, Felix H F; Sener, Beatrice; Bürgi-Tiedemann, Christine; Schmidlin, Patrick R

    2004-01-01

    This laboratory study investigated the efficiency and aggressiveness of metallic and carbonic inserts of a vertically oscillating ultrasonic device (Vector-system) at different power settings. The following parameters concerning periodontal treatment were assessed under standardized conditions: calculus and tooth substance removal, mean surface roughness and micro morphological appearance of the treated roots. Concerning the calculus removal potential, no significant differences were found between the types of insert used. The carbon fibre inserts, however, showed significantly more tooth substance loss than the metallic inserts. These findings were confirmed by micromorphological SEM analysis. In view of these results, the repeated use of these carbon fiber inserts during periodonatal sustaining therapy cannot be recommended. PMID:15587598

  12. Growth of carbon structures on chrysotile surface for organic contaminants removal from wastewater.

    PubMed

    Lemos, Bruno R S; Soares, Érico A R; Teixeira, Ana Paula C; Ardisson, José D; Fernandez-Outon, Luis E; Amorim, Camila C; Lago, Rochel M; Moura, Flávia C C

    2016-09-01

    Amphiphilic magnetic composites were produced based on chrysotile mineral and carbon structures by chemical vapor deposition at different temperatures (600-900 °C) and cobalt as catalyst. The materials were characterized by elemental analysis, X-ray diffraction, vibrating sample magnetometry, adsorption and desorption of N2, Raman spectroscopy, scanning electronic microscopy, and thermal analysis showed an effective growth of carbon structures in all temperatures. It was observed that at 800 and 900 °C, a large amount of carbon structures are formed with fewer defects than at 600 and 700 °C, what contributes to their stability. In addition, the materials present magnetic phases that are important for their application as catalysts and adsorbents. The materials have shown to be very active to remove the oil dispersed in a real sample of emulsified wastewater from biodiesel production and to remove methylene blue by adsorption and oxidation via heterogeneous Fenton mechanism. PMID:27343867

  13. Micropollutant removal in an algal treatment system fed with source separated wastewater streams.

    PubMed

    de Wilt, Arnoud; Butkovskyi, Andrii; Tuantet, Kanjana; Leal, Lucia Hernandez; Fernandes, Tânia V; Langenhoff, Alette; Zeeman, Grietje

    2016-03-01

    Micropollutant removal in an algal treatment system fed with source separated wastewater streams was studied. Batch experiments with the microalgae Chlorella sorokiniana grown on urine, anaerobically treated black water and synthetic urine were performed to assess the removal of six spiked pharmaceuticals (diclofenac, ibuprofen, paracetamol, metoprolol, carbamazepine and trimethoprim). Additionally, incorporation of these pharmaceuticals and three estrogens (estrone, 17β-estradiol and ethinylestradiol) into algal biomass was studied. Biodegradation and photolysis led to 60-100% removal of diclofenac, ibuprofen, paracetamol and metoprolol. Removal of carbamazepine and trimethoprim was incomplete and did not exceed 30% and 60%, respectively. Sorption to algal biomass accounted for less than 20% of the micropollutant removal. Furthermore, the presence of micropollutants did not inhibit C. sorokiniana growth at applied concentrations. Algal treatment systems allow simultaneous removal of micropollutants and recovery of nutrients from source separated wastewater. Nutrient rich algal biomass can be harvested and applied as fertilizer in agriculture, as lower input of micropollutants to soil is achieved when algal biomass is applied as fertilizer instead of urine. PMID:26546707

  14. A Review on Alternative Carbon Sources for Biological Treatment of Nitrate Waste

    NASA Astrophysics Data System (ADS)

    Dhamole, Pradip B.; D'Souza, S. F.; Lele, S. S.

    2015-04-01

    Huge amount of wastewater containing nitrogen is produced by various chemical and biological industries. Nitrogen is present in the form of ammonia, nitrate and nitrite. This review deals with treatment of nitrate based effluent using biological denitrification. Because of its adverse effect on aquatic life and human health, treatment of nitrate bearing effluents has become mandatory before discharge. Treatment of such wastes is a liability for the industries and incurs cost. However, the economics of the process can be controlled by selection of proper method and reduction in the operating cost. This paper reviews the advantages and disadvantages of different methods of nitrate removal with emphasis on biological denitrification. The cost of biological denitrification is controlled by the carbon source. Hence, use of alternative carbon sources such as agricultural wastes, industrial effluent or by products is reviewed in this paper. Policies for reducing the cost of nitrate treatment and enhancing the efficiency have been recommended.

  15. Tamarind (Tamarindus indica) fruit shell carbon: A calcium-rich promising adsorbent for fluoride removal from groundwater.

    PubMed

    Sivasankar, V; Rajkumar, S; Murugesh, S; Darchen, A

    2012-07-30

    Tamarindus indica fruit shells (TIFSs) are naturally calcium rich compounds. They were impregnated with ammonium carbonate and then carbonized, leading to ammonium carbonate activated ACA-TIFS carbon. The resulting materials and carbon arising from virgin fruit shells V-TIFS were characterized and assayed as adsorbent for the removal of fluoride anions from groundwater. The fluoride scavenging ability of TIFS carbons was due to naturally dispersed calcium compounds. X-ray diffraction (XRD) showed that TIFS carbon contained a mixture of calcium oxalate and calcium carbonate. Batch studies on the fluoride removal efficiency of TIFS carbons with respect to contact time, pH, initial fluoride concentration, and co-ion interference were conducted. Applicability of various kinetic models (viz., pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich) and sorption isotherms were tested for batch techniques. The fluoride removal capacity of TIFS carbons was found to be 91% and 83% at a pH of 7.05 for V-TIFS and ACA-TIFS carbons, respectively. The practical applicability of TIFS carbons using groundwater samples was approved. The fluoride removal was greater in groundwater without hydrogen carbonate ions than those containing these ions. The characterizations of fluoride unloaded and loaded TIFS carbons were done by SEM and XRD studies. PMID:22626627

  16. Bisphenol A removal by combination of powdered activated carbon adsorption and ultrafiltration

    NASA Astrophysics Data System (ADS)

    Wang, Rongchang; Tong, Hao; Xia, Siqing; Zhang, Yalei; Zhao, Jianfu

    2010-11-01

    Bisphenol A (BPA) removal from surface water in the presence of natural organic matter (NOM) by combination of powdered activated carbon (PAC) adsorption and ultrafiltration (UF) was investigated in this study. It was especially focused on the effects of various factors on BPA removal, such as PAC dosage, NOM concentration and pH value. BPA removal by UF+PAC process increased sharply from 4% to 92%, when PAC dosage increased from 0 to 120 mg/L. The optimal PAC dosage was determined to be 30 mg/L. The results also showed that BPA retention was slightly favored in the presence of NOM. As pH increased from 7.0 to 10.5, BPA removal substantially decreased from 90% to 59%. PAC+UF process is recommended to be used as an emergence facility in drinking water treatment, especially when an accidental spilling of deleterious substance, e.g., BPA, in the water resources happens.

  17. Chemoselective Synthesis of Carbamates using CO2 as Carbon Source.

    PubMed

    Riemer, Daniel; Hirapara, Pradipbhai; Das, Shoubhik

    2016-08-01

    Synthesis of carbamates directly from amines using CO2 as the carbon source is a straightforward and sustainable approach. Herein, we describe a highly effective and chemoselective methodology for the synthesis of carbamates at room temperature and atmospheric pressure. This methodology can also be applied to protect the amino group in amino acids and peptides, and also to synthesize important pharmaceuticals. PMID:27376902

  18. A mobile light source for carbon/nitrogen cameras

    NASA Astrophysics Data System (ADS)

    Trower, W. P.; Karev, A. I.; Melekhin, V. N.; Shvedunov, V. I.; Sobenin, N. P.

    1995-05-01

    The pulsed light source for carbon/nitrogen cameras developed to image concealed narcotics/explosives is described. This race-track microtron will produce 40 mA pulses of 70 MeV electrons, have minimal size and weight, and maximal ruggedness and reliability, so that it can be transported on a truck.

  19. MBBR system performance improvement for petroleum hydrocarbon removal using modified media with activated carbon.

    PubMed

    Sayyahzadeh, Amir Hossein; Ganjidoust, Hossein; Ayati, Bita

    2016-01-01

    Moving bed biofilm reactor (MBBR) system has a successful operation in the treatment of different types of wastewater. Since the media, i.e. the place of growth and formation of biofilm, play the main role in the treatment in this system, MBBR systems were operated in the present research with modified Bee-cell media. Activated carbon granules of almond or walnut shells were placed in media pores to improve the treatment of refinery oil wastewater and their operation with MBBR system was compared with the conventional Bee-cell media. In these experiments, the effects of organic loading rate, hydraulic retention time (HRT), media filling ratio (MFR), and activated carbon concentration (ACC) used in the media were investigated on the operation of MBBR systems. The analysis of results estimated the optimal values of HRT, MFR, and ACC used in the media between the studied levels, being equal to 22 h, 50%, and 7.5 g/L, respectively. Under these conditions, total petroleum hydrocarbons removal efficiencies for MBBR systems using Bee-cell media with carbon of almond, carbon of walnut shells, and a carbon-free system were 95 ± 1.17%, 91 ± 1.11%, and 57 ± 1.7%, respectively, which confirms the adsorption ability of systems with the media containing activated carbon in the removal of petroleum compounds from wastewater. PMID:27148731

  20. Arsenate removal from water by zero-valent iron/activated carbon galvanic couples.

    PubMed

    Dou, Xiaomin; Li, Rui; Zhao, Bei; Liang, Wenyan

    2010-10-15

    Galvanic couples composed of zero-valent iron and activated carbon (Fe(0)/AC) were investigated for As(V) removal from water. The effects of Fe(0) to AC mass ratio (FCR), solution pH, ionic strength and co-existing anions (phosphate, carbonate, silicate, nitrate, chloride and sulfate) and humic acid (HA) on As(V) removal were evaluated. The results showed that the optimum mass ratio was 1:1, and Fe(0)/AC with this ratio was more effective for As(V) removal than Fe(0) and AC alone at pH of 7 and ion strength of 0.03 M NaCl. The enhanced performance for As(V) removal was fulfilled through an accelerated corrosion process of Fe(0), which meant more corrosion products for efficient As(V) removal. The As(V) removal followed a pseudo-first order reaction. The rate constants (k) for 1:1 Fe(0)/AC and Fe(0) alone were 0.802 and 0.330 h(-1), respectively. Potentiodynamic polarization scans further confirmed that Fe(0) corrosion was promoted when Fe(0) was coupled with AC. Except silicates, other co-existing anions promoted As(V) removal. No reduction form of As (As(III) or As(0)) could be detected on iron corrosion products (ICPs) and in solutions. Identified ICPs included poorly crystallized lepidocrocite (gamma-FeOOH) and magnetite/maghemite (Fe(3)O(4)/gamma-Fe(2)O(3)) for both of Fe(0)/AC and Fe(0) systems. In conclusion, the Fe(0)/AC couple exhibited higher As removal performance than that of Fe(0) alone from water. PMID:20599323

  1. Selective Removal of Residual Orthodontic Composite Using a Rapidly Scanned Carbon Dioxide Laser with Spectral Feedback

    NASA Astrophysics Data System (ADS)

    Hirasuna, Krista

    Background and Objective: Excessive heat accumulation within the tooth, incomplete removal of composite, and variable damage to the enamel are shortcomings of using conventional burs to remove residual orthodontic composite after debonding fixed appliances. The objective of this study was to determine if composite could be selectively removed from the enamel surface using a rapidly scanned carbon dioxide laser controlled by spectral feedback. Materials and Methods: A carbon dioxide laser operating at a wavelength of 9.3 microm with a pulse duration of 10-15 micros and a pulse repetition rate of ˜ 200 Hz was used to selectively remove composite from the buccal surfaces of 21 extracted teeth. GrenGloo(TM) composite was used to better visualize residual composite and the amount of enamel lost was measured with optical microscopy. A spectral feedback system utilizing a miniature spectrometer was used to control the laser scanning system. Pulpal temperature measurements were performed during composite removal to determine if there was excessive heat accumulation. Results: The amount of enamel lost averaged 22.7microm +/- 8.9 and 25.3 microm +/- 9.4 for removal at 3.8 and 4.2 J/cm2, respectively. An average maximum temperature rise of 1.9°C +/- 1.5 was recorded, with no teeth approaching the critical value of 5.5°C. The average time of composite removal was 19.3 +/- 4.1 seconds. Conclusions: Residual orthodontic composite can be rapidly removed from the tooth surface using a rapidly scanned CO2 laser with spectral feedback, with minimal temperature rise within the pulp and with minimal damage to the underlying enamel surface.

  2. Removal of perfluorinated surfactants by sorption onto granular activated carbon, zeolite and sludge.

    PubMed

    Ochoa-Herrera, Valeria; Sierra-Alvarez, Reyes

    2008-08-01

    Perfluorinated surfactants are emerging pollutants of increasing public health and environmental concern due to recent reports of their world-wide distribution, environmental persistence and bioaccumulation potential. Treatment methods for the removal of anionic perfluorochemical (PFC) surfactants from industrial effluents are needed to minimize the environmental release of these pollutants. Removal of PFC surfactants from aqueous solutions by sorption onto various types of granular activated carbon was investigated. Three anionic PFC surfactants, i.e., perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS), were evaluated for the ability to adsorb onto activated carbon. Additionally, the sorptive capacity of zeolites and sludge for PFOS was compared to that of granular activated carbon. Adsorption isotherms were determined at constant ionic strength in a pH 7.2 phosphate buffer at 30 degrees C. Sorption of PFOS onto activated carbon was stronger than PFOA and PFBS, suggesting that the length of the fluorocarbon chain and the nature of the functional group influenced sorption of the anionic surfactants. Among all adsorbents evaluated in this study, activated carbon (Freundlich K(F) values=36.7-60.9) showed the highest affinity for PFOS at low aqueous equilibrium concentrations, followed by the hydrophobic, high-silica zeolite NaY (Si/Al 80, K(F)=31.8), and anaerobic sludge (K(F)=0.95-1.85). Activated carbon also displayed a superior sorptive capacity at high soluble concentrations of the surfactant (up to 80 mg l(-1)). These findings indicate that activated carbon adsorption is a promising treatment technique for the removal of PFOS from dilute aqueous streams. PMID:18511099

  3. Reduction of nitrous oxide emissions from partial nitrification process by using innovative carbon source (mannitol).

    PubMed

    Zhang, Xinwen; Wang, Xiaoqing; Zhang, Jian; Huang, Xiaoyu; Wei, Dong; Lan, Wei; Hu, Zhen

    2016-10-01

    The purpose of this study was to evaluate the effect of mannitol as carbon source on nitrogen removal and nitrous oxide (N2O) emission during partial nitrification (PN) process. Laboratory-scale PN sequencing batch reactors (SBRs) were operated with mannitol and sodium acetate as carbon sources, respectively. Results showed that mannitol could remarkably reduce N2O-N emission by 41.03%, without influencing the removal efficiency of NH4(+)-N. However, it has a significant influence on nitrite accumulation ratio (NAR) and TN removal, which were 19.97% and 13.59% lower than that in PN with sodium acetate, respectively. Microbial analysis showed that the introduction of mannitol could increase the abundance of bacteria encoding nosZ genes. In addition, anti-oxidant enzymes (T-SOD, POD and CAT) activities were significantly reduced and the dehydrogenase activity had an obvious increase in mannitol system, indicating that mannitol could alleviate the inhibition of N2O reductase (N2OR) activities caused by high NO2(-)-N concentration. PMID:27423546

  4. Carbon mass balance and microbial ecology in a laboratory scale reactor achieving simultaneous sludge reduction and nutrient removal.

    PubMed

    Huang, Pei; Li, Liang; Kotay, Shireen Meher; Goel, Ramesh

    2014-04-15

    Solids reduction in activated sludge processes (ASP) at source using process manipulation has been researched widely over the last two-decades. However, the absence of nutrient removal component, lack of understanding on the organic carbon, and limited information on key microbial community in solids minimizing ASP preclude the widespread acceptance of sludge minimizing processes. In this manuscript, we report simultaneous solids reduction through anaerobiosis along with nitrogen and phosphorus removals. The manuscript also reports carbon mass balance using stable isotope of carbon, microbial ecology of nitrifiers and polyphosphate accumulating organisms (PAOs). Two laboratory scale reactors were operated in anaerobic-aerobic-anoxic (A(2)O) mode. One reactor was run in the standard mode (hereafter called the control-SBR) simulating conventional A(2)O type of activated sludge process and the second reactor was run in the sludge minimizing mode (called the modified-SBR). Unlike other research efforts where the sludge minimizing reactor was maintained at nearly infinite solids retention time (SRT). To sustain the efficient nutrient removal, the modified-SBR in this research was operated at a very small solids yield rather than at infinite SRT. Both reactors showed consistent NH3-N, phosphorus and COD removals over a period of 263 days. Both reactors also showed active denitrification during the anoxic phase even if there was no organic carbon source available during this phase, suggesting the presence of denitrifying PAOs (DNPAOs). The observed solids yield in the modified-SBR was 60% less than the observed solids yield in the control-SBR. Specific oxygen uptake rate (SOUR) for the modified-SBR was almost 44% more than the control-SBR under identical feeding conditions, but was nearly the same for both reactors under fasting conditions. The modified-SBR showed greater diversity of ammonia oxidizing bacteria and PAOs compared to the control-SBR. The diversity of PAOs

  5. Removal of acid orange 7 by guava seed carbon: a four parameter optimization study.

    PubMed

    Elizalde-González, María P; Hernández-Montoya, Virginia

    2009-08-30

    The preparation of carbon from waste materials is a recent and economic alternative for the removal of dyes. In this study four samples of carbon were obtained by thermal treatment at 1000 degrees C using as precursor the guava seed with different particle sizes. The Taguchi method was applied as an experimental design to establish the optimum conditions for the removal of acid orange 7 in batch experiments. The chosen experimental factors and their ranges were: pH (2-12), temperature (15-35 degrees C), specific surface area (50-600 m(2)g(-1)) and adsorbent dosage (16-50 mg ml(-1)). The orthogonal array L(9) and the larger the better response category were selected to determine the optimum removal conditions: pH 2, temperature 15 degrees C, S(esp) 600 m(2)g(-1) and dosage 30 mg ml(-1). Under these conditions a total removal of acid orange 7 was achieved. Moreover, the most significant factors were the carbon specific surface area and the pH. The influence of the different factors on the adsorption of acid orange 7 from solution is explained in terms of electrostatic interactions by considering the dye species and the character of the surface. PMID:19285803

  6. Optimization of magnetic powdered activated carbon for aqueous Hg(II) removal and magnetic recovery.

    PubMed

    Faulconer, Emily K; von Reitzenstein, Natalia V Hoogesteijn; Mazyck, David W

    2012-01-15

    Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 μg/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury-carbon contact chamber with mixing and constant N(2) (g) headspace flow to an oxidizing trap. Mercury adsorption was performed using spiked ultrapure water (100 μg/L Hg). Mercury concentrations were obtained using EPA method 245.1 and cold vapor atomic absorption spectroscopy. MPAC synthesis was optimized for Hg removal and sorbent recovery according to the variables: C:Fe, thermal oxidation temperature and time. The 3:1 C:Fe preserved most of the original sorbent surface area. As indicated by XRD patterns, thermal oxidation reduced the amorphous characteristic of the iron oxides but did not improve sorbent recovery and damaged porosity at higher oxidation temperatures. Therefore, the optimal synthesis variables, 3:1 C:Fe mass ratio without thermal oxidation, which can achieve 92.5% (± 8.3%) sorbent recovery and 96.3% (± 9%) Hg removal. The mass balance has been closed to within approximately ± 15%. PMID:22104766

  7. Removal of terrestrial dissolved organic carbon in aquatic ecosystems of a temperate river network.

    NASA Astrophysics Data System (ADS)

    Wollheim, W. M.; Stewart, R. J.; Aiken, G.; Butler, K. D.; Morse, N.; Salisbury, J.

    2015-12-01

    Surface waters play an important role in the global carbon balance. Dissolved organic carbon (DOC) fluxes are a major transfer of terrestrial carbon to river systems, and the net removal of terrestrial DOC in aquatic systems is poorly constrained. We used a combination of spatially distributed sampling of three DOC fractions, nitrate, and chloride in streams of different size throughout a river network and modeling to quantify the net removal of terrestrial DOC relative to other constituents during a summer base flow period. The approach was applied to the 400 km2 Ipswich River watershed, MA, USA. We found that aquatic reactivity of terrestrial DOC leading to net loss is low, closer to conservative chloride than to reactive nitrogen. Net removal of DOC occurred mainly from the hydrophobic organic acid fraction, while hydrophilic and transphilic acids showed no net change. Model fits were improved using the different DOC fractions than when using bulk DOC, indicating that partitioning of bulk DOC into different fractions is critical for understanding terrestrial DOC removal. These findings suggest that river systems may have only a modest ability to alter the amounts of terrestrial DOC delivered to coastal zones.

  8. Different carbon sources affect PCB accumulation by marine bivalves.

    PubMed

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems. PMID:26606107

  9. Photocatalytic removal of polychlorinated biphenyls (PCBs) using carbon-modified titanium oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Shaban, Yasser A.; El Sayed, Mohamed A.; El Maradny, Amr A.; Al Farawati, Radwan Kh.; Al Zobidi, Mosa I.; Khan, Shahed U. M.

    2016-03-01

    In this work, the sonicated sol-gel method was used for synthesizing carbon-modified titanium oxide nanoparticles. Carbon incorporation was achieved by using titanium (IV) isopropoxide as a titanium and carbon-containing precursor. The photocatalytic efficiency of the synthesized photocatalyst was assessed by examining the photocatalytic removal of polychlorinated biphenyls (PCBs) from aqueous solution. For comparison, unmodified (regular) titanium dioxide (n-TiO2) was used as a reference catalyst. To confirm the carbon incorporation in CM-n-TiO2 nanoparticles, energy dispersive spectroscopy (EDS) analysis was used. Significantly, the bandgap energy was found to be reduced from 2.99 eV for n-TiO2 to 1.8 eV for CM-n-TiO2, which in turn improved the performance of CM-n-TiO2 toward the photocatalytic removal of PCBs. The effects of CM-n-TiO2 loading, PCBs concentration, and pH of the solution on the photodegradation rate of PCBs were investigated. The highest removal rate was found to be at pH 5 and CM-n-TiO2 loading of 0.5 g L-1. According to Langmuir-Hinshelwood model, the photodegradation of PCBs using CM-n-TiO2 followed a pseudo-first order reaction kinetics.

  10. Coal fly ash based carbons for SO2 removal from flue gases.

    PubMed

    Rubio, B; Izquierdo, M T

    2010-07-01

    Two different coal fly ashes coming from the burning of two coals of different rank have been used as a precursor for the preparation of steam activated carbons. The performance of these activated carbons in the SO(2) removal was evaluated at flue gas conditions (100 degrees C, 1000 ppmv SO(2), 5% O(2), 6% H(2)O). Different techniques were used to determine the physical and chemical characteristics of the samples in order to explain the differences found in their behaviour. A superior SO(2) removal capacity was shown by the activated carbon obtained using the fly ash coming from a sub-bituminous-lignite blend. Experimental results indicated that the presence of higher amount of certain metallic oxides (Ca, Fe) in the carbon-rich fraction of this fly ash probably has promoted a deeper gasification in the activation with steam. A more suitable surface chemistry and textural properties have been obtained in this case which explains the higher efficiency shown by this sample in the SO(2) removal. PMID:20167465

  11. Tracking Nonpoint Source Nitrogen and Carbon in Watersheds of Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Kaushal, S.; Pennino, M. J.; Duan, S.; Blomquist, J.

    2012-12-01

    Humans have altered nitrogen and carbon cycles in rivers regionally with important impacts on coastal ecosystems. Nonpoint source nitrogen pollution is a leading contributor to coastal eutrophication and hypoxia. Shifts in sources of carbon impact downstream ecosystem metabolism and fate and transport of contaminants in coastal zones. We used a combination of stable isotopes and optical tracers to investigate fate and transport of nitrogen and carbon sources in tributaries of the largest estuary in the U.S., the Chesapeake Bay. We analyzed isotopic composition of water samples from major tributaries including the Potomac River, Susquehanna River, Patuxent River, and Choptank River during routine and storm event sampling over multiple years. A positive correlation between δ15N-NO3- and δ18O-NO3- in the Potomac River above Washington D.C. suggested denitrification or biological uptake in the watershed was removing agriculturally-derived N during summer months. In contrast, the Patuxent River in Maryland showed elevated δ15N-NO3- (5 - 12 per mil) with no relationship to δ18O-NO3- suggesting the importance of wastewater sources. From the perspective of carbon sources, there were distinct isotopic values of the δ13C-POM of particulate organic matter and fluorescence excitation emission matrices (EEMS) for rivers influenced by their dominant watershed land use. EEMS showed that there were increases in the humic and fulvic fractions of dissolved organic matter during spring floods, particularly in the Potomac River. Stable isotopic values of δ13C-POM also showed rapid depletion suggesting terrestrial carbon "pulses" in the Potomac River each spring. The δ15N-POM peaked to 10 - 15 per mil each spring suggested a potential manure source or result of biological processing within the watershed. Overall, there were considerable changes in sources and transformations of nitrogen and carbon that varied across rivers and that contribute to nitrogen and carbon loads

  12. [Removal of fluorescent whitening agent by hydrogen peroxide oxidation catalyzed by activated carbon].

    PubMed

    Liu, Hai-Long; Zhang, Zhong-Min; Zhao, Xia; Jiao, Ru-Yuan

    2014-06-01

    Degradation of fluorescent whitening agent VBL in the processes of activated carbon (AC) and activated carbon modified (ACM) adsorptions, hydrogen peroxide (H2O2) oxidation, and hydrogen peroxide oxidation catalyzed by activated carbon were studied. Mechanism of the above catalytic oxidation was also investigated by adding tert-Butyl alcohol (TBA), the free radical scavenger, and detecting the released gases. The results showed that: the activated carbon modified by Fe (NO3)3 (ACM)exhibited better adsorption removal than AC. Catalytic oxidation showed efficient removal of VBL, and the catalytic removal of AC (up to 95%) was significantly higher than that of ACM (58% only). Catalytic oxidation was inhibited by TBA, which indicates that the above reaction involved *OH radicals and atom oxygen generated by hydrogen peroxide with the presence of AC. The results of H2O2 decomposition and released gases detection involved in the process showed that activated carbon enhanced the decomposition of H2O2 which released oxygen and heat. More O2 was produced and higher temperature of the reactor was achieved, which indicated that H2O2 decomposition catalyzed by ACM was significantly faster than that of AC. Combining the results of VBL removal, it could be concluded that the rate of active intermediates (*OH radicals and atom oxygen) production by ACM catalytic reaction was faster than that of AC. These intermediates consumed themselves and produced O2 instead of degrading VBL. It seemed that the improper mutual matching of the forming rate of activating intermediates and the supply rate of reactants was an important reason for the lower efficiency of ACM catalytic reaction comparing with AC. PMID:25158496

  13. Study on the removal of pesticide in agricultural run off by granular activated carbon.

    PubMed

    Jusoh, Ahmad; Hartini, W J H; Ali, Nora'aini; Endut, A

    2011-05-01

    In this batch study, the adsorption of malathion by using granular activated carbon with different parameters due to the particle size, dosage of carbons, as well as the initial concentration of malathion was investigated. Batch tests were carried out to determine the potential and the effectiveness of granular activated carbon (GAC) in removal of pesticide in agricultural run off. The granular activated carbon; coconut shell and palm shells were used and analyzed as the adsorbent material. The Langmuir and Freundlich adsorption isotherms models were applied to describe the characteristics of adsorption behavior. Equilibrium data fitted well with the Langmuir model and Freundlich model with maximum adsorption capacity of 909.1mg/g. The results indicate that the GAC could be used to effectively adsorb pesticide (malathion) from agricultural runoff. PMID:21232934

  14. A comparison of simultaneous organic carbon and nitrogen removal in microbial fuel cells and microbial electrolysis cells.

    PubMed

    Hussain, Abid; Manuel, Michelle; Tartakovsky, Boris

    2016-05-15

    This study demonstrates simultaneous carbon and nitrogen removal in laboratory-scale continuous flow microbial fuel cell (MFC) and microbial electrolysis cell (MEC) and provides side-by side comparison of these bioelectrochemical systems. The maximum organic carbon removal rates in MFC and MEC tests were similar at 5.1 g L(-1) d(-1) and 4.16 g L(-1) d(-1), respectively, with a near 100% carbon removal efficiency at an organic load of 3.3 g L(-1) d(-1). An ammonium removal efficiency of 30-55% with near-zero nitrite and nitrate concentrations was observed in the MFC operated at an optimal external resistance, while open-circuit MFC operation resulted in a reduced carbon and ammonium removal of 53% and 21%, respectively. In the MEC ammonium removal was limited to 7-12% under anaerobic conditions, while micro-aerobic conditions increased the removal efficiency to 31%. Also, at zero applied voltage both carbon and ammonium removal efficiencies were reduced to 42% and 4%, respectively. Based on the observed performance under different operating conditions, it was concluded that simultaneous carbon and nitrogen removal was facilitated by concurrent anaerobic and aerobic biotransformation pathways at the anode and cathode, which balanced bioelectrochemical nitrification and denitrification reactions. PMID:26950500

  15. Application of Vacuum Swing Adsorption for Carbon Dioxide and Water Vapor Removal from Manned Spacecraft Atmospheres

    NASA Technical Reports Server (NTRS)

    Knox, J.; Fulda, P.; Howard, D.; Ritter, J.; Levan, M.

    2007-01-01

    The design and testing of a vacuum-swing adsorption process to remove metabolic 'water and carbon dioxide gases from NASA's Orion crew exploration vehicle atmosphere is presented. For the Orion spacecraft, the sorbent-based atmosphere revitalization (SBAR) system must remove all metabolic water, a technology approach 1Lhathas not been used in previous spacecraft life support systems. Design and testing of a prototype SBAR in sub-scale and full-scale configurations is discussed. Experimental and analytical investigations of dual-ended and single-ended vacuum desorption are presented. An experimental investigation of thermal linking between adsorbing and desorbing columns is also presented.

  16. Full System Modeling and Validation of the Carbon Dioxide Removal Assembly

    NASA Technical Reports Server (NTRS)

    Coker, Robert; Knox, James; Gauto, Hernando; Gomez, Carlos

    2014-01-01

    The Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Advanced Exploration Systems (AES) program. Under the ARREM project, testing of sub-scale and full-scale systems has been combined with multiphysics computer simulations for evaluation and optimization of subsystem approaches. In particular, this paper describes the testing and modeling of various subsystems of the carbon dioxide removal assembly (CDRA). The goal is a full system predictive model of CDRA to guide system optimization and development. The development of the CO2 removal and associated air-drying subsystem hardware under the ARREM project is discussed in a companion paper.

  17. Photoautotrophic microorganisms as a carbon source for temperate soil invertebrates.

    PubMed

    Schmidt, Olaf; Dyckmans, Jens; Schrader, Stefan

    2016-01-01

    We tested experimentally if photoautotrophic microorganisms are a carbon source for invertebrates in temperate soils. We exposed forest or arable soils to a (13)CO2-enriched atmosphere and quantified (13)C assimilation by three common animal groups: earthworms (Oligochaeta), springtails (Hexapoda) and slugs (Gastropoda). Endogeic earthworms (Allolobophora chlorotica) and hemiedaphic springtails (Ceratophysella denticulata) were highly (13)C enriched when incubated under light, deriving up to 3.0 and 17.0%, respectively, of their body carbon from the microbial source in 7 days. Earthworms assimilated more (13)C in undisturbed soil than when the microbial material was mixed into the soil, presumably reflecting selective surface grazing. By contrast, neither adult nor newly hatched terrestrial slugs (Deroceras reticulatum) grazed on algal mats. Non-photosynthetic (13)CO2 fixation in the dark was negligible. We conclude from these preliminary laboratory experiments that, in addition to litter and root-derived carbon from vascular plants, photoautotrophic soil surface microorganisms (cyanobacteria, algae) may be an ecologically important carbon input route for temperate soil animals that are traditionally assigned to the decomposer channel in soil food web models and carbon cycling studies. PMID:26740559

  18. Effect of geological carbon sources on eddy covariance measurements: analysis and possible correction approaches

    NASA Astrophysics Data System (ADS)

    Papale, D.; Rey, A.; Belelli-Marchesini, L.; Etiope, G.; Pegoraro, E.

    2013-12-01

    A recent set of studies carried out in the SE of Spain highlighted the need to consider geological carbon sources when estimating the net ecosystem carbon balance (NECB) of terrestrial ecosystems located in areas potentially affected by geofluid circulation. In this study we present the mechanisms and propose a new methodology using physical parameters of the atmospheric boundary layer to quantify the CO2 coming from deep origin. To test our approach, we compare NECB estimates with seasonal patterns of soil CO2 efflux and vegetation activity measured by satellite images (NDVI) over two-year period at this site (2007/2008). According with the eddy covariance measurements the alpha grass ecosystem was a net carbon source (93.7 and 145.0 g C m-2, for the years 2007 and 2008, respectively) particularly as a result of large amounts of carbon released over the dry period. This relevant CO2 emission (reaching up to 15 umol m-2 s-1) was however not related to ecosystem activities as confirmed by measurements of soil CO2 efflux using chambers (ca. 0.5 umol m-2 s-1) and plant productivity that was minimal during this period. A simple correction based on a linear relationship between NECB and wind speed for different stability conditions and wind sectors has been used to estimate the geological flux FGEO and subtracted it from the NECB to obtain the biological flux FBIO. We then partitioned FBIO into gross primary productivity and ecosystem respiration and proved that, after removing FGEO, ecosystem and soil respiration followed similar temporal patterns. The annual contribution of the geological component to NECB was 49.6 and 46.7 % for the year 2007 and 2008, respectively. Therefore, potential contribution of geological carbon sources should be tested and quantified in those ecosystems located in areas with potential natural emission of geologic gases to the surface. References: REY A., BELELLI MARCHESINI L., WERE A., SERRANO ORTIZ P., ETIOPE G., PAPALE D, DOMINGO F

  19. A method for preparing ferric activated carbon composites adsorbents to remove arsenic from drinking water.

    PubMed

    Zhang, Qiao Li; Lin, Y C; Chen, X; Gao, Nai Yun

    2007-09-30

    Iron oxide/activated carbon (FeO/AC) composite adsorbent material, which was used to modify the coal-based activated carbon (AC) 12 x 40, was prepared by the special ferric oxide microcrystal in this study. This composite can be used as the adsorbent to remove arsenic from drinking water, and Langmuir isotherm adsorption equation well describes the experimental adsorption isotherms. Then, the arsenic desorption can subsequently be separated from the medium by using a 1% aqueous NaOH solution. The apparent characters and physical chemistry performances of FeO/AC composite were investigated by X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Batch and column adsorption experiments were carried out to investigate and compare the arsenic removal capability of the prepared FeO/AC composite material and virgin activated carbon. It can be concluded that: (1) the main phase present in this composite are magnetite (Fe(3)O(4)), maghemite (gamma-Fe(2)O(3)), hematite (alpha-Fe(2)O(3)) and goethite (alpha-FeO(OH)); (2) the presence of iron oxides did not significantly affect the surface area or the pore structure of the activated carbon; (3) the comparisons between the adsorption isotherms of arsenic from aqueous solution onto the composite and virgin activated carbon showed that the FeO/AC composite behave an excellent capacity of adsorption arsenic than the virgin activated carbon; (4) column adsorption experiments with FeO/AC composite adsorbent showed that the arsenic could be removed to below 0.01 mg/L within 1250 mL empty bed volume when influent concentration was 0.5mg/L. PMID:17434260

  20. Removal of micropollutants from aerobically treated grey water via ozone and activated carbon.

    PubMed

    Hernández-Leal, L; Temmink, H; Zeeman, G; Buisman, C J N

    2011-04-01

    Ozonation and adsorption onto activated carbon were tested for the removal micropollutants of personal care products from aerobically treated grey water. MilliQ water spiked with micropollutants (100-1600 μgL(-1)) was ozonated at a dosing rate of 1.22. In 45 min, this effectively removed (>99%): Four parabens, bisphenol-A, hexylcinnamic aldehyde, 4-methylbenzylidene-camphor (4MBC), benzophenone-3 (BP3), triclosan, galaxolide and ethylhexyl methoxycinnamate. After 60 min, the removal efficiency of benzalkonium chloride was 98%, tonalide and nonylphenol 95%, octocrylene 92% and 2-phenyl-5-benzimidazolesulfonic acid (PBSA) 84%. Ozonation of aerobically treated grey water at an applied ozone dose of 15 mgL(-1), reduced the concentrations of octocrylene, nonylphenol, triclosan, galaxolide, tonalide and 4-methylbenzylidene-camphor to below limits of quantification, with removal efficiencies of at least 79%. Complete adsorption of all studied micropollutants onto powdered activated carbon (PAC) was observed in batch tests with milliQ water spiked with 100-1600 μgL(-1) at a PAC dose of 1.25 gL(-1) and a contact time of 5 min. Three granular activated carbon (GAC) column experiments were operated to treat aerobically treated grey water. The operation of a GAC column with aerobically treated grey water spiked with micropollutants in the range of 0.1-10 μgL(-1) at a flow of 0.5 bed volumes (BV)h(-1) showed micropollutant removal efficiencies higher than 72%. During the operation time of 1728 BV, no breakthrough of TOC or micropollutants was observed. Removal of micropollutants from aerobically treated grey water was tested in a GAC column at a flow of 2 BVh(-1). Bisphenol-A, triclosan, tonalide, BP3, galaxolide, nonylphenol and PBSA were effectively removed even after a stable TOC breakthrough of 65% had been reached. After spiking the aerobically treated effluent with micropollutants to concentrations of 10-100 μgL(-1), efficient removal to below limits of quantification

  1. A nanofilter composed of carbon nanotube-silver composites for virus removal and antibacterial activity improvement.

    PubMed

    Kim, Jun Pyo; Kim, Jae Ha; Kim, Jieun; Lee, Soo No; Park, Han-Oh

    2016-04-01

    We have developed a new nanofilter using a carbon nanotube-silver composite material that is capable of efficiently removing waterborne viruses and bacteria. The nanofilter was subjected to plasma surface treatment to enhance its flow rate, which was improved by approximately 62%. Nanoscale pores were obtained by fabricating a carbon nanotube network and using nanoparticle fixation technology for the removal of viruses. The pore size of the nanofilter was approximately 38 nm and the measured flow rate ranged from 21.0 to 97.2L/(min·m(2)) under a pressure of 1-6 kgf/cm(2) when the amount of loaded carbon nanotube-silver composite was 1.0 mg/cm(2). The nanofilter was tested against Polio-, Noro-, and Coxsackie viruses using a sensitive real-time polymerase chain reaction assay to detect the presence of viral particles within the outflow. No trace of viruses was found to flow through the nanofilter with carbon nanotube-silver composite loaded above 0.8 mg/cm(2). Moreover, the surface of the filter has antibacterial properties to prevent bacterial clogging due to the presence of 20-nm silver nanoparticles, which were synthesized on the carbon nanotube surface. PMID:27090720

  2. Fluoride removal in water by a hybrid adsorbent lanthanum-carbon.

    PubMed

    Vences-Alvarez, Esmeralda; Velazquez-Jimenez, Litza Halla; Chazaro-Ruiz, Luis Felipe; Diaz-Flores, Paola E; Rangel-Mendez, Jose Rene

    2015-10-01

    Various health problems associated with drinking water containing high fluoride levels, have motivated researchers to develop more efficient adsorbents to remove fluoride from water for beneficial concentrations to human health. The objective of this research was to anchor lanthanum oxyhydroxides on a commercial granular activated carbon (GAC) to remove fluoride from water considering the effect of the solution pH, and the presence of co-existing anions and organic matter. The activated carbon was modified with lanthanum oxyhydroxides by impregnation. SEM and XRD were performed in order to determine the crystal structure and morphology of the La(III) particles anchored on the GAC surface. FT-IR and pK(a)'s distribution were determined in order to elucidate both the possible mechanism of the lanthanum anchorage on the activated carbon surface and the fluoride adsorption mechanism on the modified material. The results showed that lanthanum ions prefer binding to carboxyl and phenolic groups on the activated carbon surface. Potentiometric titrations revealed that the modified carbon (GAC-La) possesses positive charge at a pH lower than 9. The adsorption capacity of the modified GAC increased five times in contrast to an unmodified GAC adsorption capacity at an initial F(-) concentration of 20 mg L(-1). Moreover, the presence of co-existing anions had no effect on the fluoride adsorption capacity at concentrations below 30 mg L(-1), that indicated high F(-) affinity by the modified adsorbent material (GAG-La). PMID:26070190

  3. Removal of reactive dyes from wastewater by adsorption on coir pith activated carbon.

    PubMed

    Santhy, K; Selvapathy, P

    2006-07-01

    The removal efficiency of activated carbon prepared from coir pith towards three highly used reactive dyes in textile industry was investigated. Batch experiments showed that the adsorption of dyes increased with an increase in contact time and carbon dose. Maximum de-colorisation of all the dyes was observed at acidic pH. Adsorption of dyes was found to follow the Freundlich model. Kinetic studies indicated that the adsorption followed first order and the values of the Lagergren rate constants of the dyes were in the range of 1.77 x 10(-2)-2.69 x 10(-2)min(-1). The column experiments using granular form of the carbon (obtained by agglomeration with polyvinyl acetate) showed that adsorption efficiency increased with an increase in bed depth and decrease of flow rate. The bed depth service time (BDST) analysis carried out for the dyes indicated a linear relationship between bed depth and service time. The exhausted carbon could be completely regenerated and put to repeated use by elution with 1.0M NaOH. The coir pith activated carbon was not only effective in removal of colour but also significantly reduced COD levels of the textile wastewater. PMID:16040240

  4. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal

    NASA Astrophysics Data System (ADS)

    Johnston, C. D.; Davis, G. B.; Bastow, T. P.; Woodbury, R. J.; Rao, P. S. C.; Annable, M. D.; Rhodes, S.

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L3/L2/T) and mass fluxes (Jc; M/L2/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104 g day- 1 to 24-31 g day- 1 (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions also

  5. Mass discharge assessment at a brominated DNAPL site: Effects of known DNAPL source mass removal.

    PubMed

    Johnston, C D; Davis, G B; Bastow, T P; Woodbury, R J; Rao, P S C; Annable, M D; Rhodes, S

    2014-08-01

    Management and closure of contaminated sites is increasingly being proposed on the basis of mass flux of dissolved contaminants in groundwater. Better understanding of the links between source mass removal and contaminant mass fluxes in groundwater would allow greater acceptance of this metric in dealing with contaminated sites. Our objectives here were to show how measurements of the distribution of contaminant mass flux and the overall mass discharge emanating from the source under undisturbed groundwater conditions could be related to the processes and extent of source mass depletion. In addition, these estimates of mass discharge were sought in the application of agreed remediation targets set in terms of pumped groundwater quality from offsite wells. Results are reported from field studies conducted over a 5-year period at a brominated DNAPL (tetrabromoethane, TBA; and tribromoethene, TriBE) site located in suburban Perth, Western Australia. Groundwater fluxes (qw; L(3)/L(2)/T) and mass fluxes (Jc; M/L(2)/T) of dissolved brominated compounds were simultaneously estimated by deploying Passive Flux Meters (PFMs) in wells in a heterogeneous layered aquifer. PFMs were deployed in control plane (CP) wells immediately down-gradient of the source zone, before (2006) and after (2011) 69-85% of the source mass was removed, mainly by groundwater pumping from the source zone. The high-resolution (26-cm depth interval) measures of qw and Jc along the source CP allowed investigation of the DNAPL source-zone architecture and impacts of source mass removal. Comparable estimates of total mass discharge (MD; M/T) across the source zone CP reduced from 104gday(-1) to 24-31gday(-1) (70-77% reductions). Importantly, this mass discharge reduction was consistent with the estimated proportion of source mass remaining at the site (15-31%). That is, a linear relationship between mass discharge and source mass is suggested. The spatial detail of groundwater and mass flux distributions

  6. Enhanced coagulation with powdered activated carbon or MIEX secondary treatment: a comparison of disinfection by-product formation and precursor removal.

    PubMed

    Watson, Kalinda; Farré, Maria José; Knight, Nicole

    2015-01-01

    The removal of both organic and inorganic disinfection by-product (DBP) precursors prior to disinfection is important in mitigating DBP formation, with halide removal being particularly important in salinity-impacted water sources. A matrix of waters of variable alkalinity, halide concentration and dissolved organic carbon (DOC) concentration were treated with enhanced coagulation (EC) followed by anion exchange (MIEX resin) or powdered activated carbon (PAC) and the subsequent disinfection by-product formation potentials (DBP-FPs) assessed and compared to DBP-FPs for untreated samples. Halide and DOC removal were also monitored for both treatment processes. Bromide and iodide adsorption by MIEX treatment ranged from 0 to 53% and 4-78%, respectively. As expected, EC and PAC treatments did not remove halides. DOC removal by EC/PAC was 70 ± 10%, while EC/MIEX enabled a DOC removal of 66 ± 12%. Despite the halide removals achieved by MIEX, increases in brominated disinfection by-product (Br-DBP) formation were observed relative to untreated samples, when favourable Br:DOC ratios were created by the treatment. However, the increases in formation were less than what was observed for the EC/PAC treated waters, which caused large increases in Br-DBP formation when high Br-DBP-forming water quality conditions occurred. The formation potential of fully chlorinated DBPs decreased after treatment in all cases. PMID:25462752

  7. Carbon Dioxide Adsorption on a 5A Zeolite Designed for CO2 Removal in Spacecraft Cabins

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Finn, John E.

    1998-01-01

    Carbon dioxide adsorption data were obtained for a 5A zeolite manufactured by AlliedSignal Inc. (Des Plaines, Illinois). The material is planned for use in the Carbon Dioxide Removal Assembly (CDRA) for U.S. elements of the International Space Station. The family of adsorption isotherms covers a temperature range of O to 250 C, and a pressure range of 0.001 to 800 torr. Coefficients of the Toth equation are fit to the data. Isosteric heats of adsorption are derived from the equilibrium loading data.

  8. Multi walled carbon nanotubes as sorbent for removal of crystal violet.

    PubMed

    Kumar, Sandeep; Bhanjana, Gaurav; Dilbaghi, Neeraj; Umar, Ahmad

    2014-09-01

    Carbon nanotubes (CNTs) possess high surface active site to volume ratio as well as controlled pore size distribution that make them high profile material with an exceptional sorption capability and high sorption efficiency compared to conventional adsorbents. In the present paper, multi walled carbon nanotubes were synthesized by chemical vapor deposition (CVD) method and were further used for the removal of dye crystal violet. Microscopic and spectroscopic techniques were used for characterization. The systematic assessments of the pH and effect of adsorbent on different concentrations of dye with respect to contact time were examined. Langmuir and Temkin models were used to describe the isotherm studies. PMID:25924370

  9. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery

    PubMed Central

    Jiang, Guozhan; Hill, David J.; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs’ biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels’ production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs. PMID:27447619

  10. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery.

    PubMed

    Jiang, Guozhan; Hill, David J; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs' biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels' production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs. PMID:27447619

  11. Removal of organic dyes using Cr-containing activated carbon prepared from leather waste.

    PubMed

    Oliveira, Luiz C A; Coura, Camila Van Zanten; Guimarães, Iara R; Gonçalves, Maraisa

    2011-09-15

    In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO(2) flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m(2)g(-1)). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H(2)O(2) to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes. PMID:21752544

  12. Removal of perfluorinated carboxylates from washing wastewater of perfluorooctanesulfonyl fluoride using activated carbons and resins.

    PubMed

    Du, Ziwen; Deng, Shubo; Chen, Youguang; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang

    2015-04-01

    Perfluorooctanesulfonyl fluoride (PFOSF) washing wastewater contains high concentrations of perfluorinated carboxylates (PFCAs) including perfluorohexanoate (PFHxA, 0.10 mmol/L), perfluoroheptanoate (PFHpA, 0.11 mmol/L), and perfluorooctanoate (PFOA, 0.29 mmol/L). For the first time, we investigated the removal of these PFCAs from actual wastewater using the bamboo-derived activated carbon (BAC) and resin IRA67. Adsorption kinetics, effects of adsorbent dose, solution pH, and inorganic ions, as well as regeneration and reuse experiments were studied. The removal percents of three PFCAs by BAC and IRA67 followed the increasing order of PFHxA < PFHpA < PFOA, but the adsorption equilibrium time conformed to the reverse trend. PFCAs removal on IRA67 decreased with increasing pH, but BAC almost kept stable PFCAs removal at pH above 5.0. Among competitive adsorption of three PFCAs, PFOA was preferentially adsorbed on both BAC and IRA67. PFCAs removal from actual wastewater by BAC was higher than that in simulated solution, due to the presence of high concentration of inorganic ions in the wastewater. However, the co-existing organic compounds in wastewater significantly suppressed the adsorption of PFCAs. Both spent BAC and IRA67 were successfully regenerated by ethanol solution or NaCl/methanol mixture, and IRA67 showed the stable removal of PFCAs in five adsorption cycles. PMID:25585266

  13. Removal of virus and toxin using heatable multi-walled carbon nanotube web filters

    NASA Astrophysics Data System (ADS)

    Jang, Hoon-Sik; Jeon, Sang Koo; Ryu, Kwon-Sang; Nahm, Seung Hoon

    2016-02-01

    Many studies have used a carbon nanotube (CNT) filter for pathogen removal and/or inactivation by means of electrochemical or electrochlorination. The large surface area, fine pore size and high electrical and thermal conductivity of CNTs make them suitable and distinct to use for the filtering and removal of pathogens. Here, we grew spin-capable multi-walled CNTs (MWCNTs) and manufactured a web filter using the spun MWCNTs. Botulinum toxin type E light chain (BoT/E-LC) and vaccinia virus (VV) were filtered using the MWCNT web filters and were evaporated and removed by applying direct current (DC) voltage to both sides of the MWCNT webs, excluding electrochemical or electrochlorination. The filtering and removal of BoT/E-LC and VV were performed after seven layers of the MWCNT sheets were coated onto a silicon oxide porous plate. The electrical resistance of the webs in the seven layer sheet was 293 Ω. The temperature of MWCNTs webs was linearly increased to ˜300 °C at 210 V of DC voltage. This temperature was enough to remove BoT/E-LC and VV. From the SEM and XPS results, we confirmed that BoT/E-LC and VV on the MWCNT webs were almost removed by applying a DC voltage and that some element (N, Na, Cl, etc.) as residues on the MWCNT webs remained.

  14. Phosphonate removal from discharged circulating cooling water using iron-carbon micro-electrolysis.

    PubMed

    Zhou, Zhen; Qiao, Weimin; Lin, Yangbo; Shen, Xuelian; Hu, Dalong; Zhang, Jianqiao; Jiang, Lu-Man; Wang, Luochun

    2014-01-01

    Phosphonate is a commonly used corrosion and scale inhibitor for a circulating cooling water (CCW) system. Its discharge could cause eutrophication of receiving waters. The iron-carbon (Fe/C) micro-electrolysis technology was used to degrade and remove phosphonate from discharged CCW. The influences of initial pH, Fe/C ratio (FCR) and temperature on phosphonate removal were investigated in a series of batch tests and optimized by response surface methodology. The quadratic model of phosphonate removal was obtained with satisfactory degrees of fitness. The optimum conditions with total phosphorus removal efficiency of 95% were obtained at pH 7.0, FCR of 1.25, and temperature of 45 °C. The phosphonate removal mechanisms were also studied. Phosphonate removal occurred predominantly via two consecutive reactive phases: the degradation of phosphonate complexes (Ca-phosphonate) and the precipitation of Fe/C micro-electrolysis products (PO₄(3-), Ca²⁺ and Fe³⁺). PMID:25098884

  15. Simultaneous activated carbon adsorption within a membrane bioreactor for an enhanced micropollutant removal.

    PubMed

    Li, Xueqing; Hai, Faisal I; Nghiem, Long D

    2011-05-01

    Significant adsorption of sulfamethoxazole and carbamazepine to powdered activated carbon (PAC) was confirmed by a series of adsorption tests. In contrast, adsorption of these micropollutants to the sludge was negligible. The removal of these compounds in membrane bioreactor (MBR) was dependent on their hydrophobicity and loading as well as the PAC dosage. Sulfamethoxazole exhibited better removal rate during operation under no or low (0.1g/L) PAC dosage. When the PAC concentration in MBR was raised to 1.0 g/L, a sustainable and significantly improved performance in the removal of both compounds was observed - the removal efficiencies of sulfamethoxazole and carbamazepine increased to 82 ± 11% and 92 ± 15% from the levels of 64 ± 7%, and negligible removal, respectively. The higher removal efficiency of carbamazepine at high (1.0 g/L) PAC dosage could be attributed to the fact that carbamazepine is relatively more hydrophobic than sulfamethoxazole, which subsequently resulted in its higher adsorption affinity toward PAC. PMID:21145232

  16. Measurement of Trace Water Vapor in a Carbon Dioxide Removal Assembly Product Stream

    NASA Technical Reports Server (NTRS)

    Wormhoudt, Joda; Shorter, Joanne H.; McManus, J. Barry; Nelson, David D.; Zahniser, Mark S.; Freedman, Andrew; Campbell, Melissa; Chang, Clarence T.; Smith, Frederick D.

    2004-01-01

    The International Space Station Carbon Dioxide Removal Assembly (CDRA) uses regenerable adsorption technology to remove carbon dioxide (COP) from cabin air. Product water vapor measurements from a CDRA test bed at the NASA Marshall Space Flight Center were made using a tunable infrared diode laser differential absorption spectrometer (TILDAS) provided by NASA Glenn Research Center. The TILDAS instrument exceeded all the test specifications, including sensitivity, dynamic range, time response, and unattended operation. During the COP desorption phase, water vapor concentrations as low as 5 ppmv were observed near the peak of CO2 evolution, rising to levels of approx. 40 ppmv at the end of a cycle. Periods of high water concentration (>100 ppmv) were detected and shown to be caused by an experimental artifact. Measured values of total water vapor evolved during a single desorption cycle were as low as 1 mg.

  17. Current Applications for the Use of Extracorporeal Carbon Dioxide Removal in Critically Ill Patients

    PubMed Central

    Camporota, Luigi; Barrett, Nicholas

    2016-01-01

    Mechanical ventilation in patients with respiratory failure has been associated with secondary lung injury, termed ventilator-induced lung injury. Extracorporeal venovenous carbon dioxide removal (ECCO2R) appears to be a feasible means to facilitate more protective mechanical ventilation or potentially avoid mechanical ventilation in select patient groups. With this expanding role of ECCO2R, we aim to describe the technology and the main indications of ECCO2R. PMID:26966691

  18. Synthesis of Large Pore Carbon Nanoparticles for Removal of Malachite Green.

    PubMed

    Tripathi, Pranav K; Gan, Lihua; Liu, Mingxian

    2016-01-01

    In this work, we have synthesized high surface area and large pore volume carbon nanoparticles (CNP) by a simple and easy sol-gel approach. The sol was prepared by mixing Pluronic F127 and phloroglucinol-terephthalaldehyde in acidic ethanol solution and the gel was formed after the vacuum removal of ethanol. In the sol-gel process, hydrophobic segments of Pluronic F127 forms enhanced hydrogen bonding with trihydroxyl groups of phloroglucinol. A polymeric network of carbon precursor was also prepared by making the interconnectivity between four phloroglucinol and one terephthalaldehyde molecules. After thermal polymerization and carbonization of the gel, the CNP had a very high surface area (1441 m² g⁻¹) and large pore volume (1.7 cm³ g⁻¹) with narrow micropore (1.0 nm) and mesopore (2.3 nm) diameters. The mesopore was developed due to the enhanced hydrogen bonding between Pluronic F127 and phloroglucinol, while the micropores were generated due to hydrocarbon polymeric network of phloroglucinol-terephthalaldehyde. The CNP had a size about ca. 20 nm. The CNP were applied for the removal of the highly hazardous water pollutant malachite green (MG) and achieved a very high adsorption capacity (1892 mg g⁻¹). The commercials powder activated carbon (PAC) was also applied for the removal of MG and achieved an adsorption capacity of PAC was 1390 mg g⁻¹. It believes that shape and size of CNP and PAC played an important role in the adsorptive removal of MG. PMID:27398542

  19. Comparison between two forms of granular activated carbon for the removal of pharmaceuticals from different waters.

    PubMed

    Lima, Lisandra; Baêta, Bruno E L; Lima, Diego R S; Afonso, Robson J C F; de Aquino, Sérgio F; Libânio, Marcelo

    2016-06-01

    The aim of this study was to evaluate the performance of two forms of basic granular activated carbon (GAC), mineral (pH = 10.5) and vegetal (pH = 9), for the removal of three pharmaceuticals, as sulphamethoxazole (SMX), diclofenac (DCF) and 17β-estradiol (E2), from two different matrices: fortified distilled (2.4-3.0 mg L(-1) and pH from 5.5 to 6.5) and natural (∼1.0 mg L(-1) and pH from 7.1 to 7.2) water in a bench scale. The Rapid Small-Scale Column Test used to assess the ability of mineral and vegetal GAC on removal of such pharmaceuticals led to removal capacities varying from 14.9 to 23.5 mg g(-1) for E2, from 23.7 to 24.2 mg g(-1) for DCF and from 20.5 to 20.6 mg g(-1) for SMX. Removal efficiencies of 71%, 88% and 74% for DCF, SMX and E2, respectively, were obtained at breakthrough point when using mineral GAC, whereas for the vegetal GAC the figures were 76%, 77% and 65%, respectively. The carbon usage rate at the breakthrough point varied from 11.9 to 14.5 L g(-1) for mineral GAC and from 8.8 to 14.8 L g(-1) for vegetal GAC. Mineral CAG also exhibited the best performance when treating fortified natural water, since nearly complete removal was observed for all contaminants in the column operated for 22 h at a carbon usage rate of 2.9 L g(-1). PMID:26584017

  20. Carbon-14 in methane sources and in atmospheric methane: The contribution from fossil carbon

    SciTech Connect

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J. ); Vogel, J.S.; Southon, J. ); Shemesh, A.; Fairbanks, R.; Broecker, W. )

    1989-07-21

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra is somewhat, depleted in carbon-14. Atmospheric {sup 14}CH{sub 4} seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 {plus minus} 0.8% modern carbon (pMC) in the Northern Hemisphere and 120.0 {plus minus} 0.7 pMC in the Southern Hemisphere. Model calculations of source partitioning based on the carbon-14 data, CH{sub 4} concentrations, and {delta}{sup 13}C in CH{sub 4} indicate that 21 {plus minus} 3% of atmospheric CH{sub 4} was derived from fossil carbon at the end of 1987. The data also indicate that pressurized water reactors are an increasingly important source of {sup 14}CH{sub 4}. 38 refs., 3 figs., 2 tabs.

  1. Removal of dyes from aqueous solutions using activated carbon prepared from rice husk residue.

    PubMed

    Li, Yaxin; Zhang, Xian; Yang, Ruiguang; Li, Guiying; Hu, Changwei

    2016-01-01

    The treatment of dye wastewater by activated carbon (AC) prepared from rice husk residue wastes was studied. Batch adsorption studies were conducted to investigate the effects of contact time, initial concentration (50-450 mg/L), pH (3-11) and temperature (30-70 °C) on the removal of methylene blue (MB), neutral red, and methyl orange. Kinetic investigation revealed that the adsorption of dyes followed pseudo-second-order kinetics. The results suggested that AC was effective to remove dyes, especially MB, from aqueous solutions. Desorption studies found that chemisorption by the adsorbent might be the major mode of dye removal. Fourier transform infrared results suggested that dye molecules were likely to combine with the O-H and P=OOH groups of AC. PMID:26942535

  2. Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution.

    PubMed

    López-Bernabeu, S; Ruiz-Rosas, R; Quijada, C; Montilla, F; Morallón, E

    2016-02-01

    The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential. PMID:26433936

  3. Lead and copper removal from aqueous solutions using carbon foam derived from phenol resin.

    PubMed

    Lee, Chang-Gu; Jeon, Jun-Woo; Hwang, Min-Jin; Ahn, Kyu-Hong; Park, Chanhyuk; Choi, Jae-Woo; Lee, Sang-Hyup

    2015-07-01

    Phenolic resin-based carbon foam was prepared as an adsorbent for removing heavy metals from aqueous solutions. The surface of the produced carbon foam had a well-developed open cell structure and the specific surface area according to the BET model was 458.59m(2)g(-1). Batch experiments showed that removal ratio increased in the order of copper (19.83%), zinc (34.35%), cadmium (59.82%), and lead (73.99%) in mixed solutions with the same initial concentration (50mgL(-1)). The results indicated that the Sips isotherm model was the most suitable for describing the experimental data of lead and copper. The maximum adsorption capacity of lead and copper determined to Sips model were 491mgg(-1) and 247mgg(-1). The obtained pore diffusion coefficients for lead and copper were found to be 1.02×10(-6) and 2.42×10(-7)m(2)s(-1), respectively. Post-sorption characteristics indicated that surface precipitation was the primary mechanism of lead and copper removal by the carbon foam, while the functional groups on the surface of the foam did not affect metal adsorption. PMID:25819762

  4. Organic micropollutant removal from wastewater effluent-impacted drinking water sources during bank filtration and artificial recharge.

    PubMed

    Maeng, Sung Kyu; Ameda, Emmanuel; Sharma, Saroj K; Grützmacher, Gesche; Amy, Gary L

    2010-07-01

    Natural treatment systems such as bank filtration (BF) and artificial recharge (via an infiltration basin) are a robust barrier for many organic micropollutants (OMPs) and may represent a low-cost alternative compared to advanced drinking water treatment systems. This study analyzes a comprehensive database of OMPs at BF and artificial recharge (AR) sites located near Lake Tegel in Berlin (Germany). The focus of the study was on the derivation of correlations between the removal efficiencies of OMPs and key factors influencing the performance of BF and AR. At the BF site, shallow monitoring wells located close to the Lake Tegel source exhibited oxic conditions followed by prolonged anoxic conditions in deep monitoring wells and a production well. At the AR site, oxic conditions prevailed from the recharge pond along monitoring wells to the production well. Long residence times of up to 4.5 months at the BF site reduced the temperature variation during soil passage between summer and winter. The temperature variations were greater at the AR site as a consequence of shorter residence times. Deep monitoring wells and the production well located at the BF site were under the influence of ambient groundwater and old bank filtrate (up to several years of age). Thus, it is important to account for mixing with native groundwater and other sources (e.g., old bank filtrate) when estimating the performance of BF with respect to removal of OMPs. Principal component analysis (PCA) was used to investigate correlations between OMP removals and hydrogeochemical conditions with spatial and temporal parameters (e.g., well distance, residence time and depth) from both sites. Principal component-1 (PC1) embodied redox conditions (oxidation-reduction potential and dissolved oxygen), and principal component-2 (PC2) embodied degradation potential (e.g., total organic carbon and dissolved organic carbon) with the calcium carbonate dissolution potential (Ca(2+) and HCO(3)(-)) for the BF

  5. Carbon nitride films formed using sputtering and negative carbon ion sources

    SciTech Connect

    Murzin, I.H.; Tompa, G.S.; Wei, J.; Muratov, V.; Fischer, T.E.; Yakovlev, V.

    1997-12-01

    The authors report the results of using sputtering and negative carbon ion sources to prepare thin films of carbon nitride. In this work, they compare the structural, tribological, and optical properties of the carbon nitride films that were prepared by two different ion assisted techniques. In the first approach they used a magnetron gun to sputter deposit carbon in a nitrogen atmosphere. The second method utilized a beam of negatively charged carbon ions of 1 to 5 {micro}A/cm{sup 2} current density impinging the substrate simultaneously with a positive nitrogen ion beam produced by a Kaufman source. They were able to synthesize microscopically smooth coatings with the carbon to nitrogen ratio of 1:0.47. These films possess wear rates lower than 5 {times} 10{sup {minus}7} mm{sup 3}/Nm and friction coefficients in the range of 0.16 to 0.6. Raman spectroscopy revealed that the magnetron sputtered films are more structurally disordered than those formed with the negative carbon ion gun. FTIR showed the presence of the C{triple_bond}N stretching mode in both types of films. Finally, spectroscopic ellipsometry produced films with dielectric constants as low as 2.3 in the photon energy range from 1.2 to 5 eV.

  6. Removal of diclofenac by conventional drinking water treatment processes and granular activated carbon filtration.

    PubMed

    Rigobello, Eliane Sloboda; Dantas, Angela Di Bernardo; Di Bernardo, Luiz; Vieira, Eny Maria

    2013-06-01

    This study was carried out to evaluate the efficiency of conventional drinking water treatment processes with and without pre-oxidation with chlorine and chlorine dioxide and the use of granular activated carbon (GAC) filtration for the removal of diclofenac (DCF). Water treatment was performed using the Jar test with filters on a lab scale, employing nonchlorinated artesian well water prepared with aquatic humic substances to yield 20HU true color, kaolin turbidity of 70 NTU and 1mgL(-1) DCF. For the quantification of DCF in water samples, solid phase extraction and HPLC-DAD methods were developed and validated. There was no removal of DCF in coagulation with aluminum sulfate (3.47mgAlL(-1) and pH=6.5), flocculation, sedimentation and sand filtration. In the treatment with pre-oxidation and disinfection, DCF was partially removed, but the concentration of dissolved organic carbon (DOC) was unchanged and byproducts of DCF were observed. Chlorine dioxide was more effective than chorine in oxidizing DCF. In conclusion, the identification of DCF and DOC in finished water indicated the incomplete elimination of DCF through conventional treatments. Nevertheless, conventional drinking water treatment followed by GAC filtration was effective in removing DCF (⩾99.7%). In the oxidation with chlorine, three byproducts were tentatively identified, corresponding to a hydroxylation, aromatic substitution of one hydrogen by chlorine and a decarboxylation/hydroxylation. Oxidation with chlorine dioxide resulted in only one byproduct (hydroxylation). PMID:23540811

  7. Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor.

    PubMed

    Patel, Ajay; Zhu, Jesse; Nakhla, George

    2006-11-01

    In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading. PMID:16762392

  8. Sorbent Structural Testing on Carbon Dioxide Removal Sorbents for Advanced Exploration Systems

    NASA Technical Reports Server (NTRS)

    Watson, David; Knox, James C.; West, Phillip; Bush, Richard

    2016-01-01

    Long term space missions require carbon dioxide removal systems that can function with minimal downtime required for maintenance, low power consumption and maximum efficiency for CO2 removal. A major component of such a system are the sorbents used for the CO2 and desiccant beds. Sorbents must not only have adequate CO2 and H2O removal properties, but they must have the mechanical strength to prevent structural breakdown due to pressure and temperature changes during operation and regeneration, as well as resistance to breakdown due to moisture in the system from cabin air. As part of the studies used to select future CO2 sorbent materials, mechanical tests are performed on various zeolite sorbents to determine mechanical performance while dry and at various humidified states. Tests include single pellet crush, bulk crush and attrition tests. We have established a protocol for testing sorbents under dry and humid conditions, and previously tested the sorbents used on the International Space Station carbon dioxide removal assembly. This paper reports on the testing of a series of commercial sorbents considered as candidates for use on future exploration missions.

  9. Removal of micropollutants in WWTP effluent by biological assisted membrane carbon filtration (BioMAC).

    PubMed

    Weemaes, M; Fink, G; Lachmund, C; Magdeburg, A; Stalter, D; Thoeye, C; De Gueldre, G; Van De Steene, B

    2011-01-01

    In the frame of the European FP6 project Neptune, a combination of biological activated carbon with ultrafiltration (BioMAC) was investigated for micropollutant, pathogen and ecotoxicity removal. One pilot scale set-up and two lab-scale set-ups, of which in one set-up the granular activated carbon (GAC) was replaced by sand, were followed up during a period of 11 months. It was found that a combination of GAC and ultrafiltration led to an almost complete removal of antibiotics and a high removal (>80%) of most of the investigated acidic pharmaceuticals and iodinated contrast media. The duration of the tests did however not allow to conclude that the biological activation was able to extend the lifetime of the GAC. Furthermore, a significant decrease in estrogenic and anti-androgenic activity could be illustrated. The set-up in which GAC was replaced by sand showed a considerably lower removal efficiency for micropollutants, especially for antibiotics but no influence on steroid activity. PMID:21245556

  10. The Ultimate Electron Sources Using Millimeter Long Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Perea, N.; Rebollo, B.; Briones, J. A.; Morelos, A.; Hernandez, D.; Munoz, E.; Lopez-Urias, F.; Botello, A. R.; Charlier, J. C.; Meunier, V.; Hirata, G. A.; Maruyama, B.; Terrones, M.; Terrones, H.

    2012-02-01

    We are reporting the fabrication of a very efficient electron source using long and crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.10 V/μm and reach threshold emission at 0.164 V/μm. In addition, these electron sources are very stable for long operation periods up to 200 hrs and can achieve peak current density of 2 Acm-2 at only 0.28 V/μm. To demonstrate intense electron beam generation, these devices were used to produce white light by cathodoluminescence. Finally, to rational the measured properties in open carbon nanotubes of different lengths we used density functional theory. The modeling establishes a clear correlation between length and field enhancement factor.

  11. Combination of herbivore removal and nitrogen deposition increases upland carbon storage.

    PubMed

    Smith, Stuart W; Johnson, David; Quin, Samuel L O; Munro, Kyle; Pakeman, Robin J; van der Wal, René; Woodin, Sarah J

    2015-08-01

    Ecosystem carbon (C) accrual and storage can be enhanced by removing large herbivores as well as by the fertilizing effect of atmospheric nitrogen (N) deposition. These drivers are unlikely to operate independently, yet their combined effect on aboveground and belowground C storage remains largely unexplored. We sampled inside and outside 19 upland grazing exclosures, established for up to 80 years, across an N deposition gradient (5-24 kg N ha(-1) yr(-1) ) and found that herbivore removal increased aboveground plant C stocks, particularly in moss, shrubs and litter. Soil C storage increased with atmospheric N deposition, and this was moderated by the presence or absence of herbivores. In exclosures receiving above 11 kg N ha(-1) year(-1) , herbivore removal resulted in increased soil C stocks. This effect was typically greater for exclosures dominated by dwarf shrubs (Calluna vulgaris) than by grasses (Molinia caerulea). The same pattern was observed for ecosystem C storage. We used our data to predict C storage for a scenario of removing all large herbivores from UK heathlands. Predictions were made considering herbivore removal only (ignoring N deposition) and the combined effects of herbivore removal and current N deposition rates. Predictions including N deposition resulted in a smaller increase in UK heathland C storage than predictions using herbivore removal only. This finding was driven by the fact that the majority of UK heathlands receive low N deposition rates at which herbivore removal has little effect on C storage. Our findings demonstrate the crucial link between herbivory by large mammals and atmospheric N deposition, and this interaction needs to be considered in models of biogeochemical cycling. PMID:25930662

  12. Removal of micropollutants in municipal wastewater treatment plants by powder-activated carbon.

    PubMed

    Boehler, M; Zwickenpflug, B; Hollender, J; Ternes, T; Joss, A; Siegrist, H

    2012-01-01

    Micropollutants (MP) are only partly removed from municipal wastewater by nutrient removal plants and are seen increasingly as a threat to aquatic ecosystems and to the safety of drinking water resources. The addition of powder activated carbon (PAC) is a promising technology to complement municipal nutrient removal plants in order to achieve a significant reduction of MPs and ecotoxicity in receiving waters. This paper presents the salient outcomes of pilot- and full-scale applications of PAC addition in different flow schemes for micropollutant removal in municipal wastewater treatment plants (WWTPs). The sorption efficiency of PAC is reduced with increasing dissolved organic carbon (DOC). Adequate treatment of secondary effluent with 5-10 g DOC m(-3) requires 10-20 g PAC m(-3) of effluent. Counter-current use of PAC by recycling waste PAC from post-treatment in a contact tank with an additional clarifier to the biology tank improved the overall MP removal by 10 to 50% compared with effluent PAC application alone. A dosage of 15 g PAC m(-3) to a full-scale flocculation sand filtration system and recycling the backwash water to the biology tank showed similar MP elimination. Due to an adequate mixing regime and the addition of adapted flocculants, a good retention of the fine fraction of the PAC in the deep-bed filter were observed (1-3 g TSS m(-3); TSS: total suspended solids). With double use of PAC, only half of the PAC was required to reach MP removal efficiencies similar to the direct single dosage of PAC to the biology tank. Overall, the application of PAC in WWTPs seems to be an adequate and feasible technology for efficient MP elimination (>80%) from wastewater comparable with post ozonation. PMID:22949241

  13. Ceria modified activated carbon: an efficient arsenic removal adsorbent for drinking water purification

    NASA Astrophysics Data System (ADS)

    Sawana, Radha; Somasundar, Yogesh; Iyer, Venkatesh Shankar; Baruwati, Babita

    2016-03-01

    Ceria (CeO2) coated powdered activated carbon was synthesized by a single step chemical process and demonstrated to be a highly efficient adsorbent for the removal of both As(III) and As(V) from water without any pre-oxidation process. The formation of CeO2 on the surface of powdered activated carbon was confirmed by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The percentage of Ce in the adsorbent was confirmed to be 3.5 % by ICP-OES. The maximum removal capacity for As(III) and As(V) was found to be 10.3 and 12.2 mg/g, respectively. These values are comparable to most of the commercially available adsorbents. 80 % of the removal process was completed within 15 min of contact time in a batch process. More than 95 % removal of both As(III) and As(V) was achieved within an hour. The efficiency of removal was not affected by change in pH (5-9), salinity, hardness, organic (1-4 ppm of humic acid) and inorganic anions (sulphate, nitrate, chloride, bicarbonate and fluoride) excluding phosphate. Presence of 100 ppm phosphate reduced the removal significantly from 90 to 18 %. The equilibrium adsorption pattern of both As(III) and As(V) fitted well with the Freundlich model with R 2 values 0.99 and 0.97, respectively. The material shows reusability greater than three times in a batch process (arsenic concentration reduced below 10 ppb from 330 ppb) and a life of at least 100 L in a column study with 80 g material when tested under natural hard water (TDS 1000 ppm, pH 7.8, hardness 600 ppm as CaCO3) spiked with 330 ppb of arsenic.

  14. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    SciTech Connect

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu E-mail: zouguifu@suda.edu.cn; Gao, Peng; Zhang, Ke-Qin E-mail: zouguifu@suda.edu.cn; Du, Dezhuang; Guo, Jun

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  15. Methane and carbon at equilibrium in source rocks

    PubMed Central

    2013-01-01

    Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized. PMID:24330266

  16. Use of magnesit as a magnesium source for ammonium removal from leachate.

    PubMed

    Gunay, Ahmet; Karadag, Dogan; Tosun, Ismail; Ozturk, Mustafa

    2008-08-15

    Using magnesit (MgCO(3)) as a low cost source of magnesium ions in the struvite precipitation for the removal of high ammonium content of leachate was evaluated. Optimum molar concentration and pH conditions were analyzed to minimize the struvite solubility. Since solubility of magnesit in water is low, HCl was used to obtain soluble Mg. Maximum soluble Mg was obtained for the addition of 2 M HCl to the 1 M MgCO(3). Struvite precipitation with magnesit was effective for the removal of ammonium, suspended solid, phosphate and turbidity. Economical evaluation was made comparing the costs of two magnesium sources, MgCl(2) and MgCO(3). The economical analysis has shown that operation cost of struvite precipitation can be reduced about 18% by using MgCO(3) instead of MgCl(2). High salt concentration after struvite precipitation has no inhibitory effect on the anaerobic reactor performance. PMID:18243541

  17. Removal of two waterborne pathogenic bacterial strains by activated carbon particles prior to and after charge modification.

    PubMed

    Busscher, Henk J; Dijkstra, Rene J B; Engels, Eefje; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C

    2006-11-01

    Waterborne diseases constitute a threat to public health despite costly treatment measures aimed at removing pathogenic microorganisms from potable water supplies. This paper compared the removal of Raoultella terrigena ATCC 33257 and Escherichia coli ATCC 25922 by negatively and positively charged types of activated carbon particles. Both strains display bimodal negative zeta-potential distributions in stabilized water. Carbon particles were suspended to an equivalent external geometric surface area of 700 cm2 in 250 mL of a bacterial suspension, with shaking. Samples were taken after different durations for plate counting. Initial removal rates were less elevated for the positively charged carbon particle than expected, yielding the conclusion that bacterial adhesion under shaking is mass-transport limited. After 360 min, however, the log-reduction of the more negatively charged R. terrigena in suspension was largest for the positively charged carbon particles as compared with the negatively charged ones, although conditioning in ultrapure or tap water of positively charged carbon particles for 21 days eliminated the favorable effect of the positive charge due to counterion adsorption from the water. Removal of the less negatively charged E. coli was less affected by aging of the (positively charged) carbon particles, confirming the role of electrostatic interactions in bacterial removal by activated carbon particles. The microporous, negatively charged coconut carbon performed less than the mesoporous, positively charged carbon particle prior to conditioning but did not suffer from loss of effect after conditioning in ultrapure or tap water. PMID:17144313

  18. Ultrasonically enhanced leaching: removal and destruction of cyanide and other ions from used carbon cathodes.

    PubMed

    Saterlay, A J; Hong, Q; Compton, R G; Clarkson, J

    2000-01-01

    The used carbon cathodes ('Spent Pot Lining', SPL) from aluminium smelting are typically contaminated with F-, CN- and Na+ which must be removed before disposal to produce material which satisfies environmental guidelines in respect of maximum rates of ion release. Leaching of powdered and crushed carbon samples in aqueous solution were studied in the presence and absence of ultrasound. First, it was demonstrated that the total leaching of F-, CN- and Na+ from the carbon powder could be accomplished after approximately 20 min of sonication using ultrasound. Second, carbon particles (< 5 mm) showed leaching characteristics under ultrasound which were in good quantitative agreement with the National River Authority (NRA) test under silent conditions; the former being a much more rapid (approximately 1 h compared to 24 h for the NRA test) but equivalent method to the latter standard test. Third, the removed CN- ions were found to be destroyed in the presence of ultrasound, possibly via the oxidative action of hydrogen peroxide generated by the sonication of water. PMID:10643631

  19. Terrestrial sources and sinks of carbon inferred from terrestrial data

    NASA Astrophysics Data System (ADS)

    Houghton, R. A.

    1996-09-01

    Two approaches have been used to calculate changes in terrestrial carbon storage with data obtained from terrestrial ecosystems, rather than with atmospheric or oceanographic data. One approach is based on the changes in carbon that result from changes in land use (conversion of forest to agricultural land, abandonment of agricultural land, harvest and regrowth). The other approach uses measurements of forest biomass obtained through forests inventories to determine change directly. These latter studies may also calculate changes in the amount of carbon stored in wood products and soil, but in this respect the two approaches are similar. If a significant fraction of the missing carbon sink is to be found in mid-latitude forests, one would expect direct measurement of biomass to show greater accumulations of carbon than analyses in which calculated accumulations result only from regrowth following previous harvests or abandonment of agricultural land. Data from Canada, the conterminous US, Europe, and the former USSR show this circumstance to be correct. Accumulations of carbon in biomass and soil are 0.8 PgC yr-1 greater than expected from past management practices (land-use change). In the tropics (where forest inventories are rare), the total net flux of carbon from changes in land use (1.6 PgC yr-1) is consistent with recent estimates of flux based on atmospheric data, but the geographic distribution of the flux is not the same. Globally, terrestrial ecosystems are calculated to have been a net source of 0.8±0.6 PgC yr-1 during the 1980s.

  20. Bisphenol A removal by a Pseudomonas aeruginosa immobilized on granular activated carbon and operating in a fluidized bed reactor.

    PubMed

    Mita, Luigi; Grumiro, Laura; Rossi, Sergio; Bianco, Carmen; Defez, Roberto; Gallo, Pasquale; Mita, Damiano Gustavo; Diano, Nadia

    2015-06-30

    Serratia rubidiae, Pseudomonas aeruginosa and Escherichia coli K12 have been studied for their ability of Bisphenol A removal from aqueous systems and biofilm formation on activated granule carbon. Mathematical equations for biodegradation process have been elaborated and discussed. P. aeruginosa was found the best strain to be employed in the process of Bisphenol A removal. The yield in BPA removal of a P. aeruginosa biofilm grown on GAC and operating in a fluidized bed reactor has been evaluated. The results confirm the usefulness in using biological activated carbon (BAC process) to remove phenol compounds from aqueous systems. PMID:25781217

  1. CO2 Compressor Requirements for Integration of Space Station Carbon Dioxide Removal and Carbon Dioxide Reduction Assemblies

    NASA Technical Reports Server (NTRS)

    Jeng, Frank F.; Lewis, John F.; Graf, John; LaFuse, Sharon; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    This paper describes the analysis on integration requirements, CO2 compressor in particular, for integration of Carbon Dioxide Removal Assembly (CDRA) and CO2 Reduction Assembly (CRA) as a part of the Node 3 project previously conducted at JSC/NASA. A system analysis on the volume and operation pressure range of the CO2 accumulator was conducted. The hardware and operational configurations of the CO2 compressor were developed. The performance and interface requirements of the compressor were specified. An existing Four-Bed Molecular Sieve CO2 removal computer model was modified into a CDRA model and used in analyzing the requirements of the CDRA CO2 compressor. This CDRA model was also used in analyzing CDRA operation parameters that dictate CO2 pump sizing. Strategy for the pump activation was also analyzed.

  2. Removal of carbon contaminations by RF plasma generated reactive species and subsequent effects on optical surface

    SciTech Connect

    Yadav, P. K. Rai, S. K.; Modi, M. H.; Nayak, M.; Lodha, G. S.; Kumar, M.; Chakera, J. A.; Naik, P. A.

    2015-06-24

    Carbon contamination on optical elements is a serious issue in synchrotron beam lines for several decades. The basic mechanism of carbon deposition on optics and cleaning strategies are not fully understood. Carbon growth mechanism and optimized cleaning procedures are worldwide under development stage. Optimized RF plasma cleaning is considered an active remedy for the same. In present study carbon contaminated optical test surfaces (carbon capped tungsten thin film) are exposed for 30 minutes to four different gases, rf plasma at constant power and constant dynamic pressure. Structural characterization (thickness, roughness and density) of virgin samples and plasma exposed samples was done by soft x-ray (λ=80 Å) reflectivity measurements at Indus-1 reflectivity beam line. Different gas plasma removes carbon with different rate (0.4 to 0.65 nm /min). A thin layer 2 to 9 nm of different roughness and density is observed at the top surface of tungsten film. Ar gas plasma is found more suitable for cleaning of tungsten surface.

  3. Enhanced Salt Removal in an Inverted Capacitive Deionization Cell Using Amine Modified Microporous Carbon Cathodes.

    PubMed

    Gao, Xin; Omosebi, Ayokunle; Landon, James; Liu, Kunlei

    2015-09-15

    Microporous SpectraCarb carbon cloth was treated using nitric acid to enhance negative surface charges of COO(-) in a neutral solution. This acid-treated carbon was further modified by ethylenediamine to attach -NH2 surface functional groups, resulting in positive surface charges of -NH3(+) via pronation in a neutral solution. Through multiple characterizations, in comparison to pristine SpectraCarb carbon, amine-treated SpectraCarb carbon displays a decreased potential of zero charge but an increased point of zero charge, which is opposed to the effect obtained for acid-treated SpectraCarb carbon. An inverted capacitive deionization cell was constructed using amine-treated cathodes and acid-treated anodes, where the cathode is the negatively polarized electrode and the anode is the positively polarized electrode. Constant-voltage switching operation using NaCl solution showed that the salt removal capacity was approximately 5.3 mg g(-1) at a maximum working voltage of 1.1/0 V, which is an expansion in both the salt capacity and potential window from previous i-CDI results demonstrated for carbon xerogel materials. This improved performance is accounted for by the enlarged cathodic working voltage window through ethylenediamine-derived functional groups, and the enhanced microporosity of the SpectraCarb electrodes for salt adsorption. These results expand the use of i-CDI for efficient desalination applications. PMID:26302134

  4. Removal of carbon contaminations by RF plasma generated reactive species and subsequent effects on optical surface

    NASA Astrophysics Data System (ADS)

    Yadav, P. K.; Kumar, M.; Rai, S. K.; Modi, M. H.; Chakera, J. A.; Nayak, M.; Naik, P. A.; Lodha, G. S.

    2015-06-01

    Carbon contamination on optical elements is a serious issue in synchrotron beam lines for several decades. The basic mechanism of carbon deposition on optics and cleaning strategies are not fully understood. Carbon growth mechanism and optimized cleaning procedures are worldwide under development stage. Optimized RF plasma cleaning is considered an active remedy for the same. In present study carbon contaminated optical test surfaces (carbon capped tungsten thin film) are exposed for 30 minutes to four different gases, rf plasma at constant power and constant dynamic pressure. Structural characterization (thickness, roughness and density) of virgin samples and plasma exposed samples was done by soft x-ray (λ=80 Å) reflectivity measurements at Indus-1 reflectivity beam line. Different gas plasma removes carbon with different rate (0.4 to 0.65 nm /min). A thin layer 2 to 9 nm of different roughness and density is observed at the top surface of tungsten film. Ar gas plasma is found more suitable for cleaning of tungsten surface.

  5. The removal of organic pollutants by ultrafiltration and adsorption onto fibrous activated carbon

    SciTech Connect

    Le Cloirec, P.; Brasquet, C.; Subrenat, E.

    1996-10-01

    The adsorption of micropollutants in aqueous solutions showed a high adsorption velocity of fiber activated carbon (FAC) compared to granular activated carbon (GAC), and was similar to that of powder activated carbon (PAC). A selectivity of FAC was also found. From these results an ultrafiltration (LTF) membrane is coupled with FAC to remove successively macromolecules (humic substances) and phenols present together in an aqueous solution. This new and original approach to a water treatment compact process is successfully put to use. The influence of operating parameters such as water velocities, between 0.6 and 2.07 m. h{sup -1} and FAC thickness in the range 4 to 16 mm is investigated. Industrial developments are put forward.

  6. Removal of Lead (II) Ions from Aqueous Solutions onto Activated Carbon Derived from Waste Biomass

    PubMed Central

    Erdem, Murat; Ucar, Suat; Karagöz, Selhan; Tay, Turgay

    2013-01-01

    The removal of lead (II) ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II) ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS) analysis after adsorption reveals the accumulation of lead (II) ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2 mg g−1. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous. PMID:23853528

  7. [Removal characters of ozone-biological activated carbon process for typical pollutants in southern brooky regions of China].

    PubMed

    Lin, Tao; Chen, Wei; Wang, Lei-Lei

    2009-05-15

    The products of relative molecular weight (Mr) distribution, bromate (BrO3(-)) and trihalomethanes (THMs) were studied by ozone-biological activated carbon (O3-BAC) process for treating organic matters and bromide (Br(-)) in water source of southern brooky regions of China. The experimental results showed that dissolved organic matters (DOC) with Mr lower than 10(3) accounted for 80% of the total. The removal rate of DOC and SUVA (UV254/DOC) were 8% and 14% respectively by traditional treatment process with main removalonly for ones with Mr higher than 100 x 10(3). Only 30% of DOC and 31% of SUVA were decreased by O3-BAC process for the removal of ones with Mr between 10(3) and 5 x 10(3), in which the biotic degradation was certainly restricted by predominant organic matters of hydrophilic and Mr was lower than 1000. An obvious increase of BrO3(-) occurred in the effluent from ozone oxidation process when the dose of ozone beyond 2 mg/L which increased Br(-) concentration. This could increase the product of BrO3(-). A poor and unstable removal effect of BrO3(-) was observed in the effluent of BAC process during the experiment. Each species of THMs, decreasing 40% of total, was reduced by O3-BAC treatment compared with the traditional treatment process. But the products of brominated trihalomethanes, especially CHBr3 would be markedly increased by enhanced chlorine dosage and Br(-) concentration. PMID:19558108

  8. Removal of iodide from water by chlorination and subsequent adsorption on powdered activated carbon.

    PubMed

    Ikari, Mariya; Matsui, Yoshihiko; Suzuki, Yuta; Matsushita, Taku; Shirasaki, Nobutaka

    2015-01-01

    Chlorine oxidation followed by treatment with activated carbon was studied as a possible method for removing radioactive iodine from water. Chlorination time, chlorine dose, the presence of natural organic matter (NOM), the presence of bromide ion (Br⁻), and carbon particle size strongly affected iodine removal. Treatment with superfine powdered activated carbon (SPAC) after 10-min oxidation with chlorine (1 mg-Cl₂/L) removed 90% of the iodine in NOM-containing water (dissolved organic carbon concentration, 1.5 mg-C/L). Iodine removal in NOM-containing water increased with increasing chlorine dose up to 0.1 mg-Cl₂/L but decreased at chlorine doses of >1.0 mg-Cl₂/L. At a low chlorine dose, nonadsorbable iodide ion (I⁻) was oxidized to adsorbable hypoiodous acid (HOI). When the chlorine dose was increased, some of the HOI reacted with NOM to form adsorbable organic iodine (organic-I). Increasing the chlorine dose further did not enhance iodine removal, owing to the formation of nonadsorbable iodate ion (IO₃⁻). Co-existing Br⁻ depressed iodine removal, particularly in NOM-free water, because hypobromous acid (HOBr) formed and catalyzed the oxidation of HOI to IO₃⁻. However, the effect of Br⁻ was small in the NOM-containing water because organic-I formed instead of IO₃⁻. SPAC (median particle diameter, 0.62 μm) had a higher equilibrium adsorption capacity for organic-I than did conventional PAC (median diameter, 18.9 μm), but the capacities of PAC and SPAC for HOI were similar. The reason for the higher equilibrium adsorption capacity for organic-I was that organic-I was adsorbed principally on the exterior of the PAC particles and not inside the PAC particles, as indicated by direct visualization of the solid-phase iodine concentration profiles in PAC particles by field emission electron probe microanalysis. In contrast, HOI was adsorbed evenly throughout the entire PAC particle. PMID:25462731

  9. Oxygen and carbon requirements for biological nitrogen removal processes accomplishing nitrification, nitritation, and anammox.

    PubMed

    Daigger, Glen T

    2014-03-01

    The oxygen and carbon savings associated with novel nitrogen removal processes for the treatment of high ammonia, low biodegradable organic matter waste streams such as the recycle streams from the dewatering of anaerobically digested sludges are well documented.This understanding may lead some to think that similar oxygen savings are possible if novel processes such as nitritation/ denitritation and partial nitritation-deammonification are incorporated into main liquid stream processes where influent biodegradable organic matter is used to denitrify residual oxidized nitrogen (nitrite and nitrate). It is demonstrated that the net oxygen required for nitrogen removal is 1.71 mg O2/mg ammonia-nitrogen converted to nitrogen gas as long as influent biodegradable organic matter is used to denitrify residual oxidized nitrogen. Less oxygen is required to produce oxidized nitrogen with these novel processes, but less biodegradable organic matter is also required for oxidized nitrogen reduction to nitrogen gas, resulting in reduced oxygen savings for the oxidation of biodegradable organic matter. The net oxygen requirement is the same since the net electron transfer for the conversion of ammonia-nitrogen to nitrogen gas is the same. The biodegradable organic matter required to reduce the oxidized nitrogen to nitrogen gas is estimated for these processes based on standard biological process calculations. It is estimated to be in the range of 3.5 to 4.0 mg biodegradable COD/mg ammonia-nitrogen reduced to nitrogen gas for nitrification-denitrification, 2.0 to 2.5 for nitritation-denitritation, and 0.5 for partial nitritation-deammonification. The resulting limiting influent wastewater carbon-to-nitrogen ratios are estimated and can be used to guide the appropriate selection of biological nitrogen removal process given knowledge of the biological process influent wastewater carbon-to-nitrogen ratio. Energy savings possible for mainstream processes incorporating these novel

  10. A novel control strategy for efficient biological phosphorus removal with carbon-limited wastewaters.

    PubMed

    Guerrero, Javier; Guisasola, Albert; Baeza, Juan A

    2014-01-01

    This work shows the development and the in silico evaluation of a novel control strategy aiming at successful biological phosphorus removal in a wastewater treatment plant operating in an A(2)/O configuration with carbon-limited influent. The principle of this novel approach is that the phosphorus in the effluent can be controlled with the nitrate setpoint in the anoxic reactor as manipulated variable. The theoretical background behind this control strategy is that reducing nitrate entrance to the anoxic reactor would result in more organic matter available for biological phosphorus removal. Thus, phosphorus removal would be enhanced at the expense of increasing nitrate in the effluent (but always below legal limits). The work shows the control development, tuning and performance in comparison to open-loop conditions and to two other conventional control strategies for phosphorus removal based on organic matter and metal addition. It is shown that the novel proposed strategy achieves positive nutrient removal results with similar operational costs to the other control strategies and open-loop operation. PMID:25116500

  11. Comparative performance of cement kiln dust and activated carbon in removal of cadmium from aqueous solutions.

    PubMed

    El-Refaey, Ahmed A

    2016-01-01

    This study compared the performance of cement kiln dust (CKD) as industrial byproduct and commercially activated carbon (AC) as adsorbent derived from agricultural waste for the removal of cadmium (Cd(2+)) from aqueous solutions. CKD and AC were characterized by Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) and surface areas demonstrate the differences of physicochemical properties. Batch equilibrium experiments were conducted for various intervals extended to 96 h at 20, 25 and 30°C to investigate the efficiency of the sorbents in the removal of Cd(2+). CKD expressed high affinity for removal of Cd(2+) and was not affected by temperature, while AC was significantly affected, which reflects dissimilarity in the retention mechanisms defendant in CKD and those pursued by AC. The results were explained by changes of FTIR and SEM images before and after sorption experiments. The suggestion is that electrostatic ion exchange and complex reactions are the main mechanisms for Cd(2+) removal. The kinetic data were evaluated by fractional power, Elovich, pseudo-first order and pseudo-second-order kinetic models. The pseudo-second-order kinetic model was found to correlate with the experimental data well. These results revealed that CKD can be used as a cost-effective and efficient sorbent for Cd(2+) removal in comparison with AC. PMID:27054742

  12. [Rice straw and sewage sludge as carbon sources for sulfate-reducing bacteria treating acid mine drainage].

    PubMed

    Su, Yu; Wang, Jin; Peng, Shu-chuan; Yue, Zheng-bo; Chen, Tian-hu; Jin, Jie

    2010-08-01

    The performance of three organic carbon sources was assessed in terms of sulfate reduction and main metal removal, by using sewage sludge as the source of sulfate-reducing bacteria (SRB) and adding rice straw and ethanol with equal quantity. Results indicated that sewage sludge which contained certain amount of alkaline material could neutralize acidity of acid mine drainage(AMD) on the first day of experiment, elevating pH value from the initial 2.5 to around 5.4-6.3 and achieving suitable pH condition for SRB growth. Sewage sludge contained fewer biodegradable organic substance, reactive mixture with single sewage sludge showed the lowest sulfate reduction (65.9%). When the single sewage sludge was supplemented with rice straw, SRB reducing sulfate was enhanced (79.2%), because the degradation rate of rice straw was accelerated by the specific bacteria in sewage sludge, providing relatively abundant carbon source for SRB. Control experiment with ethanol was most effective in promoting sulfate reduction (97.9%). Metal removal efficiency in all three reactors was as high as 99% for copper, early copper removal was mainly attributed to the adsorption capacity of sewage sludge prior to SRB acclimation. It is feasible for using rice straw and sewage sludge as carbon sources for SRB treating acid mine drainage at a low cost, this may have significant implication for in situ bioremediation of mine environment. PMID:21090305

  13. Comparative Study of Carbon Materials Synthesized “Greenly” for 2-CP Removal

    PubMed Central

    Ma, Ying; Lu, Nan; Lu, Ying; Guan, Jiu-nian; Qu, Jiao; Liu, Hai-yang; Cong, Qiao; Yuan, Xing

    2016-01-01

    Carbon nanotubes (CNTs), graphene (GA) and carbon nanospheres (CNSs) were prepared respectively using grass (Festucaarundinace) as the sole carbon resource by solvothermal method and characterized as adsorbent and photocatalyst for 2-chlorophenol (2-CP) removal in water. With H2O2/HNO3/H2SO4, the CNTs were firstly produced from grass (Festucaarundinace) at 300 °C by hydrolysis and oxidization, the CNTs were secondly opened to form the GA by oxidization at 400 °C, and the GA was lastly rolled-up to form the CNSs by oxidization at 500 °C. All adsorption equilibration of the CNTs, GA, and CNSs for 2-CP were achieved within 120 min, and 60.35%, 20.12%, and 76.22% of 2-CP (5 mg L−1, pH = 6.3) were adsorbed, respectively. Furthermore, the high removal rates of 2-CP were about 88.23%, 92.90%, and 79.64% by the CNTs, GA, and CNSs, after 120 min adsorption and 160 min irradiation. On the basis of these results, the CNSs were suitable for removal 2-CP as adsorbent, and the GA was suitable as photocatalyst. The photooxidation of 2-CP was mainly initiated by O2·− or ·OH which was generated from the combine with simulated sunlight and the CNTs or GA, respectively. However, the CNTs was not suitable for removal 2-CP owing to the increasing toxicity. PMID:27374997

  14. Comparative Study of Carbon Materials Synthesized “Greenly” for 2-CP Removal

    NASA Astrophysics Data System (ADS)

    Ma, Ying; Lu, Nan; Lu, Ying; Guan, Jiu-Nian; Qu, Jiao; Liu, Hai-Yang; Cong, Qiao; Yuan, Xing

    2016-07-01

    Carbon nanotubes (CNTs), graphene (GA) and carbon nanospheres (CNSs) were prepared respectively using grass (Festucaarundinace) as the sole carbon resource by solvothermal method and characterized as adsorbent and photocatalyst for 2-chlorophenol (2-CP) removal in water. With H2O2/HNO3/H2SO4, the CNTs were firstly produced from grass (Festucaarundinace) at 300 °C by hydrolysis and oxidization, the CNTs were secondly opened to form the GA by oxidization at 400 °C, and the GA was lastly rolled-up to form the CNSs by oxidization at 500 °C. All adsorption equilibration of the CNTs, GA, and CNSs for 2-CP were achieved within 120 min, and 60.35%, 20.12%, and 76.22% of 2-CP (5 mg L‑1, pH = 6.3) were adsorbed, respectively. Furthermore, the high removal rates of 2-CP were about 88.23%, 92.90%, and 79.64% by the CNTs, GA, and CNSs, after 120 min adsorption and 160 min irradiation. On the basis of these results, the CNSs were suitable for removal 2-CP as adsorbent, and the GA was suitable as photocatalyst. The photooxidation of 2-CP was mainly initiated by O2·‑ or ·OH which was generated from the combine with simulated sunlight and the CNTs or GA, respectively. However, the CNTs was not suitable for removal 2-CP owing to the increasing toxicity.

  15. Comparative Study of Carbon Materials Synthesized "Greenly" for 2-CP Removal.

    PubMed

    Ma, Ying; Lu, Nan; Lu, Ying; Guan, Jiu-Nian; Qu, Jiao; Liu, Hai-Yang; Cong, Qiao; Yuan, Xing

    2016-01-01

    Carbon nanotubes (CNTs), graphene (GA) and carbon nanospheres (CNSs) were prepared respectively using grass (Festucaarundinace) as the sole carbon resource by solvothermal method and characterized as adsorbent and photocatalyst for 2-chlorophenol (2-CP) removal in water. With H2O2/HNO3/H2SO4, the CNTs were firstly produced from grass (Festucaarundinace) at 300 °C by hydrolysis and oxidization, the CNTs were secondly opened to form the GA by oxidization at 400 °C, and the GA was lastly rolled-up to form the CNSs by oxidization at 500 °C. All adsorption equilibration of the CNTs, GA, and CNSs for 2-CP were achieved within 120 min, and 60.35%, 20.12%, and 76.22% of 2-CP (5 mg L(-1), pH = 6.3) were adsorbed, respectively. Furthermore, the high removal rates of 2-CP were about 88.23%, 92.90%, and 79.64% by the CNTs, GA, and CNSs, after 120 min adsorption and 160 min irradiation. On the basis of these results, the CNSs were suitable for removal 2-CP as adsorbent, and the GA was suitable as photocatalyst. The photooxidation of 2-CP was mainly initiated by O2(·-) or ·OH which was generated from the combine with simulated sunlight and the CNTs or GA, respectively. However, the CNTs was not suitable for removal 2-CP owing to the increasing toxicity. PMID:27374997

  16. Role of metabolite transporters in source-sink carbon allocation

    PubMed Central

    Ludewig, Frank; Flügge, Ulf-Ingo

    2013-01-01

    Plants assimilate carbon dioxide during photosynthesis in chloroplasts. Assimilated carbon is subsequently allocated throughout the plant. Generally, two types of organs can be distinguished, mature green source leaves as net photoassimilate exporters, and net importers, the sinks, e.g., roots, flowers, small leaves, and storage organs like tubers. Within these organs, different tissue types developed according to their respective function, and cells of either tissue type are highly compartmentalized. Photoassimilates are allocated to distinct compartments of these tissues in all organs, requiring a set of metabolite transporters mediating this intercompartmental transfer. The general route of photoassimilates can be briefly described as follows. Upon fixation of carbon dioxide in chloroplasts of mesophyll cells, triose phosphates either enter the cytosol for mainly sucrose formation or remain in the stroma to form transiently stored starch which is degraded during the night and enters the cytosol as maltose or glucose to be further metabolized to sucrose. In both cases, sucrose enters the phloem for long distance transport or is transiently stored in the vacuole, or can be degraded to hexoses which also can be stored in the vacuole. In the majority of plant species, sucrose is actively loaded into the phloem via the apoplast. Following long distance transport, it is released into sink organs, where it enters cells as source of carbon and energy. In storage organs, sucrose can be stored, or carbon derived from sucrose can be stored as starch in plastids, or as oil in oil bodies, or – in combination with nitrogen – as protein in protein storage vacuoles and protein bodies. Here, we focus on transport proteins known for either of these steps, and discuss the implications for yield increase in plants upon genetic engineering of respective transporters. PMID:23847636

  17. Trace metal source terms in carbon sequestration environments.

    PubMed

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2013-01-01

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO(2) or CO(2)-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO(2). Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs by an order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality. PMID:23215015

  18. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios; Torres, Sharon G.; Hakala, Jacqueline A.; Shao, Hongbo; Cantrell, Kirk J.; Carroll, Susan A.

    2013-01-01

    ABSTRACT: Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO2 or CO2-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define to provide a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO2. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs byan order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality.

  19. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2012-02-05

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising, however, possible CO₂ or CO₂-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define trace metal source terms from the reaction of supercritical CO₂, storage reservoir brines, reservoir and cap rocks. Storage reservoir source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from sandstones, shales, carbonates, evaporites, basalts and cements from the Frio, In Salah, Illinois Basin – Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution is tracked by measuring solution concentrations over time under conditions (e.g. pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for Maximum Contaminant Levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments due to the presence of CO₂. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rock exceed the MCLs by an order of magnitude while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the reservoir and caprock source term to further evaluate the impact of leakage on groundwater quality.

  20. Cytotoxicity screening of single-walled carbon nanotubes: detection and removal of cytotoxic contaminants from carboxylated carbon nanotubes.

    PubMed

    Wang, Ruhung; Mikoryak, Carole; Li, Synyoung; Bushdiecker, David; Musselman, Inga H; Pantano, Paul; Draper, Rockford K

    2011-08-01

    This study compares the cytotoxicity to cultured mammalian cells of nine different single-walled carbon nanotube (SWNT) products synthesized by a variety of methods and obtained from a cross section of vendors. A standard procedure involving sonication and centrifugation in buffered bovine serum albumin was developed to disperse all the SWNTs in a biocompatible solution to facilitate comparisons. The effect of the SWNTs on the proliferative ability of a standard cell line was then assessed. Of the nine different SWNT materials tested, only two were significantly toxic, and both were functionalized by carboxylation from different vendors. This was unexpected because carboxylation makes SWNTs more water-soluble, which would presumably correlate with better biocompatibility. However, additional purification work demonstrated that the toxic material in the carboxylated SWNT preparations could be separated from the SWNTs by filtration. The filtrate that contained the toxic activity also contained abundant small carbon fragments that had Raman signatures characteristic of amorphous carbon species, suggesting a correlation between toxicity and oxidized carbon fragments. The removal of a toxic contaminant associated with carboxylated SWNTs is important in the development of carboxylated SWNTs for pharmacological applications. PMID:21688794

  1. Direct membrane-carbonation photobioreactor producing photoautotrophic biomass via carbon dioxide transfer and nutrient removal.

    PubMed

    Kim, Hyun-Woo; Cheng, Jing; Rittmann, Bruce E

    2016-03-01

    An advanced-material photobioreactor, the direct membrane-carbonation photobioreactor (DMCPBR), was tested to investigate the impact of directly submerging a membrane carbonation (MC) module of hollow-fiber membranes inside the photobioreactor. Results demonstrate that the DMCPBR utilized over 90% of the supplied CO2 by matching the CO2 flux to the C demand of photoautotrophic biomass growth. The surface area of the submerged MC module was the key to control CO2 delivery and biomass productivity. Tracking the fate of supplied CO2 explained how the DMCPBR reduced loss of gaseous CO2 while matching the inorganic carbon (IC) demand to its supply. Accurate fate analysis required that the biomass-associated C include soluble microbial products as a sink for captured CO2. With the CO2 supply matched to the photosynthetic demand, light attenuation limited the rate microalgal photosynthesis. The DMCPBR presents an opportunity to improve CO2-deliver efficiency and make microalgae a more effective strategy for C-neutral resource recovery. PMID:26771923

  2. Strategies for the removal of halides from drinking water sources, and their applicability in disinfection by-product minimisation: a critical review.

    PubMed

    Watson, K; Farré, M J; Knight, N

    2012-11-15

    The presence of bromide (Br(-)) and iodide (I(-)) in source waters leads to the formation of brominated and iodinated disinfection by-products (DBPs), which are often more toxic than their chlorinated analogues. The increasing scarcity of water resources in Australia is leading to use of impaired and alternative water supplies with high bromide and iodide levels, which may result in the production of more brominated and iodinated DBPs. This review aims to provide a summary of research into bromide and iodide removal from drinking water sources. Bromide and iodide removal techniques have been broadly classified into three categories, namely; membrane, electrochemical and adsorptive techniques. Reverse osmosis, nanofiltration and electrodialysis membrane techniques are reviewed. The electrochemical techniques discussed are electrolysis, capacitive deionization and membrane capacitive deionization. Studies on bromide and iodide removal using adsorptive techniques including; layered double hydroxides, impregnated activated carbons, carbon aerogels, ion exchange resins, aluminium coagulation and soils are also assessed. Halide removal techniques have been compared, and areas for future research have been identified. PMID:22810000

  3. Sources and sinks of carbon dioxide in the Arctic regions

    SciTech Connect

    Gosink, T. A.; Kelley, J. J.

    1982-01-01

    The data base required to adequately ascertain seasonal source and sink strengths in the arctic regions is difficult to obtain. However, there are now a reasonable quantity of data for this polar region to estimate sources and sinks within the Arctic which may contribute significantly to the annual tropospheric CO/sub 2/ concentration fluctuation. The sea-ice-air and the sea-air interfaces account for most of the contribution to the sources and sinks for carbon dioxide. Although the arctic and subarctic region is small in extent, it certainly is not impervious and ice sealed. Our estimate, based on historical data and current research, indicates that the Arctic, which is about 4% of the earth's surface, is an annual net sink for approx. 10/sup 15/ g CO/sub 2/ accounting for an equivalent of approx. 3% of the annual anthropogenic contribution of CO/sub 2/ to the troposphere.

  4. A Carbon Nanotube Electron Source Based Ionization Vacuum Gauge

    SciTech Connect

    Changkun Dong; Ganapati Myneni

    2003-10-01

    The results of fabrication and performance of an ionization vacuum gauge using a carbon nanotube (CNT) electron source are presented. The electron source was constructed with multi-wall nanotubes (MWNT), which were grown using thermal chemical vapor deposition (CVD) process. The electron emission of the source was stable in vacuum pressure up to 10-7 Torr, which is better than the metal field emitters. The measurement linearity of the gauge was better than {+-}10% from 10-6 to 10-10 Torr. The gauge sensitivity of 4 Torr-1 was achieved under 50 {micro}A electron emission in nitrogen. The gauge is expected to find applications in vacuum measurements from 10-7 Torr to below 10-11 Torr.

  5. Utilization of carbon sources in a northern Brazilian mangrove ecosystem

    NASA Astrophysics Data System (ADS)

    Giarrizzo, Tommaso; Schwamborn, Ralf; Saint-Paul, Ulrich

    2011-12-01

    Carbon and nitrogen stable isotope ratios ( 13C and 15N) and trophic level (TL) estimates based on stomach content analysis and published data were used to assess the contribution of autotrophic sources to 55 consumers in an intertidal mangrove creek of the Curuçá estuary, northern Brazil. Primary producers showed δ 13C signatures ranging between -29.2 and -19.5‰ and δ 15N from 3.0 to 6.3‰. The wide range of the isotopic composition of carbon of consumers (-28.6 to -17.1‰) indicated that different autotrophic sources are important in the intertidal mangrove food webs. Food web segregation structures the ecosystem into three relatively distinct food webs: (i) mangrove food web, where vascular plants contribute directly or indirectly via POM to the most 13C-depleted consumers (e.g. Ucides cordatus and zooplanktivorous food chains); (ii) algal food web, where benthic algae are eaten directly by consumers (e.g. Uca maracoani, mullets, polychaetes, several fishes); (iii) mixed food web where the consumers use the carbon from different primary sources (mainly benthivorous fishes). An IsoError mixing model was used to determine the contributions of primary sources to consumers, based on δ 13C values. Model outputs were very sensitive to the magnitude of trophic isotope fractionation and to the variability in 13C data. Nevertheless, the simplification of the system by a priori aggregation of primary producers allowed interpretable results for several taxa, revealing the segregation into different food webs.

  6. Effect of inorganic carbon on the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor.

    PubMed

    Chen, You-Peng; Li, Shan; Fang, Fang; Guo, Jin-Song; Zhang, Qiang; Gao, Xu

    2012-12-01

    Ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) are autotrophic microorganisms. Inorganic carbon (IC) is their main carbon source. The effects of IC limitation on AOB and AnAOB in the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor (SBBR) were examined. The optimal IC concentration in the influent was investigated. The start-up time of the CANON process from the activated sludge in the SBBR was 80 d under controlled free ammonia (FA) conditions and sufficient IC source. The AOB and AnAOB activities were limited by an IC concentration of 50 mg-C-L(-1) in the influent, whilst the nitrogen loading rate (NLR) was 200 mg-N x L(-1) x d(-1). The experiment on recovering the influent IC showed that AOB and AnAOB activities were affected by the IC limitation, and not by the pH or FA, at 200mg-N x L(-1) x d(-1) NLR and 50mg-C x L(-1) IC in the CANON process. The activities were recovered by increasing the IC concentration in the influent. From an economic point of view, the optimal IC concentration in the influent was 250mg-C x L(-1) at 200mg-N x L(-1) x d(-1) NLR in this CANON system. PMID:23437661

  7. Carbon sources and fates in the Gulf of Papua

    NASA Astrophysics Data System (ADS)

    Goni, M. A.; Monacci, N. M.; Gisewhite, R. A.; Ogston, A.; Crockett, J.; Nittrouer, C.

    2006-12-01

    Seabed sediments were collected along the particle-dispersal system associated with the Fly River-Gulf of Papua continental margin as part of the source to sink program in Papua New Guinea. Box and kasten cores were collected from the subaqueous delta located adjacent to the mouth of the Fly River as well as from the topset, foreset and bottomset regions of the active clinoform in the northern region of the Gulf of Papua. Analyses of elemental (organic carbon, inorganic carbon, nitrogen), stable isotopic (d13C and d15N), radiocarbon (14C), and biomarker (CuO oxidation products) signatures reveal significant differences in the content and composition of sedimentary organic matter (OM) along the dispersal system. The major sources of OM to the system appear to be remains of vascular plants, soil OM from the drainage basin, and materials derived from autochthonous productivity. The geographical contrasts in the concentrations and accumulation fluxes of these distinct types of allochthonous and autochthonous OM are presented in the context of patterns of sediment transport and deposition within the region. An overall OM budget for the whole dispersal system will be presented and its implication for carbon sequestration in fluvial-dominated continental margins discussed.

  8. Venovenous carbon dioxide removal in chronic obstructive pulmonary disease: experience in one patient.

    PubMed

    Cardenas, Victor J; Lynch, James E; Ates, Reyhan; Miller, Lucinda; Zwischenberger, Joseph B

    2009-01-01

    Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States. Acute exacerbations of COPD account for up to 84% of the total economic cost of this disease. The altered mechanics of the COPD patient represent a unique challenge to the clinician instituting assisted ventilation in this population. We developed an alternative mode of limited extracorporeal support termed Venovenous carbon dioxide removal (VVCO2R). We report our first case using VVCO2R, a 42-year-old white woman with a history of COPD and asthma, who was a heavy smoker at the time of admission. We utilized a compact, low flow pediatric extracorporeal circuit interposed with a low resistance gas exchange device. Venovenous carbon dioxide removal allowed for a reduction in the patient's minute ventilation to 30% of baseline with improved arterial blood gases (ABGs), a reduction in peak airway pressures and improvement in her hyperinflation. Our experience demonstrates that this system can effectively remove CO2 safely in a single cannula venous configuration while maintaining minimal anticoagulation. We believe this system could potentially be utilized in any medical or surgical intensive care unit. PMID:19512886

  9. Removal of CO2 in a multistage fluidized bed reactor by diethanol amine impregnated activated carbon.

    PubMed

    Das, Dipa; Samal, Debi Prasad; Meikap, Bhim C

    2016-07-28

    To mitigate the emission of carbon dioxide (CO2), we have developed and designed a four-stage fluidized bed reactor. There is a counter current exchange between solid adsorbent and gas flow. In this present investigation diethanol amine (DEA) impregnated activated carbon made from green coconut shell was used as adsorbent. This type of adsorbent not only adsorbs CO2 due to the presence of pore but also chemically reacts with CO2 and form secondary zwitterions. Sampling and analysis of CO2 was performed using Orsat apparatus. The effect of initial CO2 concentration, gas velocity, solid rate, weir height etc. on removal efficiency of CO2 have been investigated and presented. The percentage removal of CO2 has been found close to 80% under low gas flow rate (0.188 m/s), high solid flow rate (4.12 kg/h) and weir height of 50 mm. From this result it has been found out that multistage fluidized bed reactor may be a suitable equipment for removal of CO2 from flue gas. PMID:27163861

  10. Enhancing zero valent iron based natural organic matter removal by mixing with dispersed carbon cathodes.

    PubMed

    Liu, Peng; Keller, Jurg; Gernjak, Wolfgang

    2016-04-15

    Former studies have shown that adding granular activated carbon (GAC) cathodes could enhance the overall performance of the zero valent iron (ZVI) process for organics removal. The present study evaluates for the first time the performance of such an enhanced ZVI process to remove natural organic matter (NOM), an important water quality parameter in drinking water. Lab-scale batch tests were conducted with surface reservoir feed water from a drinking water plant. In the GAC enhanced ZVI process dissolved organic carbon (DOC) and UV254 were reduced by 61±3% and 70±2%, respectively, during 24h treatment corresponding to 1.8min empty bed contact time. The process was superior to ZVI alone, particularly during the earlier stages of the process due to the synergistically increased iron dissolution rate. Besides GAC, graphite and anthracite also prove to be suitable and potentially more cost-effective options as cathode materials for the enhanced ZVI process, whereby electrically conductive graphite clearly outperformed anthracite. The dominant mechanisms in terms of NOM removal from surface water were found to be coagulation following iron dissolution and adsorption in the case of employing GAC. Oxidation was also occurring to a lesser degree, converting some non-biodegradable into biodegradable DOC. PMID:26808400

  11. The effect of surface modification on heavy metal ion removal from water by carbon nanoporous adsorbent

    NASA Astrophysics Data System (ADS)

    Baniamerian, M. J.; Moradi, S. E.; Noori, A.; Salahi, H.

    2009-12-01

    In this work, chemically oxidized mesoporous carbon (COMC) with excellent lead adsorption performance was prepared by an acid surface modification method from mesoporous carbon (MC) by wet impregnation method. The structural order and textural properties of the mesoporous materials were studied by XRD, SEM, and nitrogen adsorption. The presence of carboxylic functional groups on the carbon surface was confirmed by FT-IR analysis. Batch adsorption experiments were conducted to study the effect of adsorbent dose, initial concentration and temperature for the removal of Pb(II) from aqueous systems. The adsorption was maximum for the initial pH in the range of 6.5-8.0. The kinetic data were best fitted to the pseudo-second order model. The adsorption of chemically oxidized mesoporous carbon to Pb(II) fits to the Langmuir model. The larger adsorption capacity of chemically oxidized mesoporous carbon for Pb(II) is mainly due to the oxygenous functional groups formed on the surface of COMC which can react with Pb(II) to form salt or complex deposited on the surface of MC.

  12. Porous graphitized carbon for adsorptive removal of benzene and the electrothermal regeneration.

    PubMed

    Li, Jinjun; Lu, Renjie; Dou, Baojuan; Ma, Chunyan; Hu, Qiuhong; Liang, Yan; Wu, Feng; Qiao, Shizhang; Hao, Zhengping

    2012-11-20

    Graphitized carbons with mesoporous and macroporous structures were synthesized by a facile template-catalysis procedure using resorcinol and formaldehyde as carbon precursors and particulate hydrated metal oxides as both template and catalyst precursors. The materials were used as novel adsorbents for low-concentration benzene vapor. Furthermore, on the basis of the good electrical conductivities associated with the graphitized structures, an electrothermal desorption technique, which involved passing electric currents through the adsorbents to generate Joule heat, was employed to regenerate the saturated adsorbents and produce enriched benzene vapors. In comparison to microporous activated carbon, the porous graphitized carbons could afford a much quicker and more efficient regeneration by electrothermal desorption technique due to their enhanced conductivity and larger pore sizes. In addition, the concentration of the desorbed organics could be controlled by adjusting the applied voltages, which might be interesting for practical secondary treatment. It is promising that the joint utilization of porous graphitized carbon adsorbents and electrothermal desorption technique might develop effective and energy-saving processes for VOCs removal. PMID:23092151

  13. Biological treatment of acidic coal refuse using sulphate-reducing bacteria with chicken manure as carbon source.

    PubMed

    Zhang, Mingliang; Wang, Haixia

    2014-01-01

    The performance of using chicken manure as carbon source to promote sulphate-reducing bacteria (SRB) activity within acidic coal refuse to prevent the generation of acidic leachate was investigated in batch and column bioreactors. The bioreactors showed satisfactory performance in biological sulphate reduction, evidenced by the increase in effluent pH, high removal efficiencies of sulphate and metals, and the presence of large numbers of SRB. Scanning electron microscope-energy dispersive spectrometry (EDS) analysis of the formed precipitate indicated the formation of metal sulphides. Chicken manure was observed to play an important role in this treatment, which could not only provide carbon source but also reduce the adverse effect of strong acidity and metal toxicity on SRB activity. Metal removal could be mainly attributed to sulphides precipitation and sorption to chicken manure. This study indicated that SRB with chicken manure could be a novel alternative used for the prevention of acidic leachate from coal refuse. PMID:25189842

  14. The removal of nutrients from non-point source wastewater by a hybrid bioreactor.

    PubMed

    Wu, Yonghong; Hu, Zhengyi; Yang, Linzhang; Graham, Bruce; Kerr, Philip G

    2011-02-01

    The aim of this project was to establish an economical and environmentally benign biotechnology for removing nutrients from non-point source wastewater. The proposal involves a hybrid bioreactor comprised of sequential anaerobic, anoxic and aerobic (A(2)/O) processes and an eco-ditch being constructed and applied in a suburban area, Kunming, south-western China, where wastewater was discharged from an industrial park and suburban communities. The results show that the hybrid bioreactor fosters heterotrophic and autotrophic microorganisms. When the hydraulic load is 200 m(3) per day with the running mode in 12h cycles, the removal efficiencies of the nutrients were 81% for TP, 74% for TDP, 82% for TN, 79% for NO(3)-N and 86% for NH(4)-N. The improved bacterial community structure and bacterial habitats further implied enhanced water quality and indicates that the easily-deployed, affordable and environmentally-friendly hybrid bioreactor is a promising bio-measure for removing high loadings of nutrients from non-point source wastewater. PMID:21093255

  15. Removal of total organic carbon from sewage wastewater using poly(ethylenimine)-functionalized magnetic nanoparticles.

    PubMed

    Lakshmanan, Ramnath; Sanchez-Dominguez, Margarita; Matutes-Aquino, Jose A; Wennmalm, Stefan; Kuttuva Rajarao, Gunaratna

    2014-02-01

    The increased levels of organic carbon in sewage wastewater during recent years impose a great challenge to the existing wastewater treatment process (WWTP). Technological innovations are therefore sought that can reduce the release of organic carbon into lakes and seas. In the present study, magnetic nanoparticles (NPs) were synthesized, functionalized with poly(ethylenimine) (PEI), and characterized using TEM (transmission electron microscopy), X-ray diffraction (XRD), FTIR (Fourier transform infrared spectroscopy), CCS (confocal correlation spectroscopy), SICS (scattering interference correlation spectroscopy), magnetism studies, and thermogravimetric analysis (TGA). The removal of total organic carbon (TOC) and other contaminants using PEI-coated magnetic nanoparticles (PEI-NPs) was tested in wastewater obtained from the Hammarby Sjöstadsverk sewage plant, Sweden. The synthesized NPs were about 12 nm in diameter and showed a homogeneous particle size distribution in dispersion by TEM and CCS analyses, respectively. The magnetization curve reveals superparamagnetic behavior, and the NPs do not reach saturation because of surface anisotropy effects. A 50% reduction in TOC was obtained in 60 min when using 20 mg/L PEI-NPs in 0.5 L of wastewater. Along with TOC, other contaminants such as turbidity (89%), color (86%), total nitrogen (24%), and microbial content (90%) were also removed without significant changes in the mineral ion composition of wastewater. We conclude that the application of PEI-NPs has the potential to reduce the processing time, complexity, sludge production, and use of additional chemicals in the WWTP. PMID:24428551

  16. Development of activated carbon derived from banana peel for CO2 removal

    NASA Astrophysics Data System (ADS)

    Borhan, Azry; Thangamuthu, Subhashini; Taha, Mohd Faisal; Ramdan, Amira Nurain

    2015-08-01

    This research work highlights on the constraints involved in the preparation of the banana peel bio-sorbent, such as impregnation ratio, activation temperature and period of activation for reducing carbon dioxide (CO2) in the atmosphere. Micromeritics ASAP 2020 and Field Emission Scanning Electron Microscope (FESEM) were used in identifying the best sample preparation method with the largest surface area which directly contributes to the effectiveness of adsorbent in removing CO2. Sample A10 was identified to yield activated carbon with the largest surface area (260.3841 m2/g), total pore volume (0.01638 cm3/g) and pore diameter (0.2508 nm). Through nitrogen adsorption-desorption isotherm analysis, the existence of sub-micropores was proven when a combination of Type-I and Type-II isotherms were exhibited by the activated carbon produced. The results from the final adsorption test found that the material synthesized from the above mentioned parameter is capable of removing up to 1.65% wt of CO2 through adsorption at 25°C, suggesting that it can be effectively used as an adsorption material.

  17. Removal of organic contaminants from aqueous solution by cattle manure compost (CMC) derived activated carbons

    NASA Astrophysics Data System (ADS)

    Qian, Qingrong; Chen, Qinghua; Machida, Motoi; Tatsumoto, Hideki; Mochidzuki, Kazuhiro; Sakoda, Akiyoshi

    2009-04-01

    The activated carbons (ACs) prepared from cattle manure compost (CMC) with various pore structure and surface chemistry were used to remove phenol and methylene blue (MB) from aqueous solutions. The adsorption equilibrium and kinetics of two organic contaminants onto the ACs were investigated and the schematic models for the adsorptive processes were proposed. The result shows that the removal of functional groups from ACs surface leads to decreasing both rate constants for phenol and MB adsorption. It also causes the decrement of MB adsorption capacity. However, the decrease of surface functional groups was found to result in the increase of phenol adsorption capacity. In our schematic model for adsorptive processes, the presence of acidic functional groups on the surface of carbon is assumed to act as channels for diffusion of adsorbate molecules onto small pores, therefore, promotes the adsorption rate of both phenol and MB. In phenol solution, water molecules firstly adsorb on surface oxygen groups by H-bonding and subsequently form water clusters, which cause partial blockage of the micropores, deduce electrons from the π-electron system of the carbon basal planes, hence, impede or prevent phenol adsorption. On the contrary, in MB solution, the oxygen groups prefer to combine with MB + cations than water molecules, which lead to the increase of MB adsorption capacity.

  18. Quantitative monitoring of the removal of non-encapsulated material external to filled carbon nanotube samples.

    PubMed

    Martincic, Markus; Pach, Elzbieta; Ballesteros, Belén; Tobias, Gerard

    2015-12-21

    The endohedral functionalization of carbon nanotubes with both organic and inorganic materials allows the development of tailored functional hybrids whose properties benefit from the synergistic effects of the constituent compounds. Bulk filling of carbon nanotubes (CNTs) results in samples that contain a large amount of non-encapsulated material external to the CNTs. The presence of the external material is detrimental to the processing and application of the resulting hybrids. Here we introduce the use of UV-Vis spectroscopy to monitor the cleaning process, i.e. the elimination of non-encapsulated compounds. Chrome azurol S has been employed to assess the bulk removal of external samarium(iii) chloride from filled single-walled carbon nanotubes. Chrome azurol S is of interest since it can be used to quantify a large variety of materials in a fast, accurate and reliable manner. The parameters that control the cleaning process have been optimized, including the time, temperature, volume and sonication, to achieve a fast and complete removal of the external material. PMID:26556303

  19. Development of activated carbon derived from banana peel for CO{sub 2} removal

    SciTech Connect

    Borhan, Azry; Thangamuthu, Subhashini; Ramdan, Amira Nurain; Taha, Mohd Faisal

    2015-08-28

    This research work highlights on the constraints involved in the preparation of the banana peel bio-sorbent, such as impregnation ratio, activation temperature and period of activation for reducing carbon dioxide (CO{sub 2}) in the atmosphere. Micromeritics ASAP 2020 and Field Emission Scanning Electron Microscope (FESEM) were used in identifying the best sample preparation method with the largest surface area which directly contributes to the effectiveness of adsorbent in removing CO{sub 2}. Sample A10 was identified to yield activated carbon with the largest surface area (260.3841 m{sup 2}/g), total pore volume (0.01638 cm{sup 3}/g) and pore diameter (0.2508 nm). Through nitrogen adsorption-desorption isotherm analysis, the existence of sub-micropores was proven when a combination of Type-I and Type-II isotherms were exhibited by the activated carbon produced. The results from the final adsorption test found that the material synthesized from the above mentioned parameter is capable of removing up to 1.65% wt of CO{sub 2} through adsorption at 25°C, suggesting that it can be effectively used as an adsorption material.

  20. Targeted Removal of Bioavailable Metal as a Detoxification Strategy for Carbon Nanotubes

    PubMed Central

    Liu, Xinyuan; Guo, Lin; Morris, Daniel; Kane, Agnes B.; Hurt, Robert H.

    2008-01-01

    There is substantial evidence for toxicity and/or carcinogenicity upon inhalation of pure transition metals in fine particulate form. Carbon nanotube catalyst residues may trigger similar metal-mediated toxicity, but only if the metal is bioavailable and not fully encapsulated within fluid-protective carbon shells. Recent studies have documented the presence of bioavailable iron and nickel in a variety of commercial as-produced and vendor “purified” nanotubes, and the present article examines techniques to avoid or remove this bioavailable metal. First, data are presented on the mechanisms potentially responsible for free metal in “purified” samples, including kinetic limitations during metal dissolution, the re-deposition or adsorption of metal on nanotube outer surfaces, and carbon shell damage during last-step oxidation or one-pot purification. Optimized acid treatment protocols are presented for targeting the free metal, considering the effects of acid strength, composition, time, and conditions for post-treatment water washing. Finally, after optimized acid treatment, it is shown that the remaining, non-bioavailable (encapsulated) metal persists in a stable and biologically unavailable form up to two months in an in vitro biopersistence assay, suggesting that simple removal of bioavailable (free) metal is a promising strategy for reducing nanotube health risks. PMID:19255622

  1. Production of a bioflocculant from Aspergillus niger using palm oil mill effluent as carbon source.

    PubMed

    Aljuboori, Ahmad H Rajab; Uemura, Yoshimitsu; Osman, Noridah Binti; Yusup, Suzana

    2014-11-01

    This study evaluated the potential of bioflocculant production from Aspergillus niger using palm oil mill effluent (POME) as carbon source. The bioflocculant named PM-5 produced by A. niger showed a good flocculating capability and flocculating rate of 76.8% to kaolin suspension could be achieved at 60 h of culture time. Glutamic acid was the most favorable nitrogen source for A. niger in bioflocculant production at pH 6 and temperature 35 °C. The chemical composition of purified PM-5 was mainly carbohydrate and protein with 66.8% and 31.4%, respectively. Results showed the novel bioflocculant (PM-5) had high potential to treat river water from colloids and 63% of turbidity removal with the present of Ca(2+) ion. PMID:25189510

  2. Carbon Isotopic Constraints on Arctic Methane Sources, 2008-2010

    NASA Astrophysics Data System (ADS)

    Fisher, R. E.; Lowry, D.; Lanoiselle, M.; Sriskantharajah, S.; Nisbet, E. G.

    2010-12-01

    Arctic methane source strengths are particularly vulnerable to large changes with year-to year meteorological variations and with climatic change. A global increase in methane seen in 2007 (Dlugokencky et al., 2009) may have been in part be due to elevated wetland emissions caused by a warm, wet summer over large parts of Siberia. In 2010 wildfires over large areas of Russia will have added methane to the Arctic atmosphere. Carbon isotopic composition of methane in air from the Arctic arriving at a measurement station can be used to identify sources of the gas. Measurement of methane δ13C in air close to sources, including wetlands, permafrost, pine forest and submarine methane clathrate has extended the available data of source signatures of methane from northern sources. Keeling plot analysis of diurnal records from field campaigns in Arctic wetlands show that bulk wetland methane emissions are typically close to δ13CCH4 -69±1 ‰. Air samples from Zeppelin (Spitsbergen, Norway), Pallas (Finland) and Barra (Outer Hebrides, Scotland) have been regularly analysed for methane δ13C. Summer campaigns at Zeppelin point to a 13C depleted bulk Arctic source of dominantly biogenic origin, at -67‰. In spring, while the wetlands are still frozen, the source signature is more enriched, -53‰, with trajectory analysis implying a large contribution from onshore gas fields. Arctic methane emissions respond rapidly to warming with strong positive feedbacks. With rapid warming there is the potential to release large stores of carbon from permafrost and methane hydrates. Isotopic data are powerful discriminants of sources. High frequency, ideally continuous, monitoring of methane δ13C from a number of Arctic sites, onshore and offshore, coupled with back-trajectory analysis and regional modelling, will be important if future changes in Arctic source strengths are to be quantified. Reference: Dlugokencky, E. J., et al. (2009), Observational constraints on recent increases

  3. Testing sources and size of carbon release during the PETM

    NASA Astrophysics Data System (ADS)

    Chun, C. O.; Ridgwell, A. J.; Marsh, R.

    2010-12-01

    Using an intermediate complexity Earth system model (GENIE) configured for the early Eocene, we aim to test hypotheses about the size and magnitude of carbon release during the PETM. We have improved the model by adding a background wetland CH4 flux at x5 preindustrial levels. Ensemble simulations of varying alkalinity, detrital flux, and CaCO3:POC ratios are compared with pre-PETM observations of wt% CaCO3 determined initial conditions. We are then able to compare a series of transient experiments of varying amounts and sources of carbon to the same initial conditions, noting the effects of subtle changes in deep ocean ventilation that are due to perturbed surface heat and freshwater fluxes. Finally, we will discuss the potential role of CH4 released to the atmosphere during the PETM and implications for climate sensitivity.

  4. Resistively-Heated Microlith-based Adsorber for Carbon Dioxide and Trace Contaminant Removal

    NASA Technical Reports Server (NTRS)

    Roychoudhury, S.; Walsh, D.; Perry, J.

    2005-01-01

    An integrated sorber-based Trace Contaminant Control System (TCCS) and Carbon Dioxide Removal Assembly (CDRA) prototype was designed, fabricated and tested. It corresponds to a 7-person load. Performance over several adsorption/regeneration cycles was examined. Vacuum regenerations at effective time/temperature conditions, and estimated power requirements were experimentally verified for the combined CO2/trace contaminant removal prototype. The current paper details the design and performance of this prototype during initial testing at CO2 and trace contaminant concentrations in the existing CDRA, downstream of the drier. Additional long-term performance characterization is planned at NASA. Potential system design options permitting associated weight, volume savings and logistic benefits, especially as relevant for long-duration space flight, are reviewed. The technology consisted of a sorption bed with sorbent- coated metal meshes, trademarked and patented as Microlith by Precision Combustion, Inc. (PCI). By contrast the current CO2 removal system on the International Space Station employs pellet beds. Preliminary bench scale performance data (without direct resistive heating) for simultaneous CO2 and trace contaminant removal was reviewed in SAE 2004-01-2442. In the prototype, the meshes were directly electrically heated for rapid response and accurate temperature control. This allowed regeneration via resistive heating with the potential for shorter regeneration times, reduced power requirement, and net energy savings vs. conventional systems. A novel flow arrangement, for removing both CO2 and trace contaminants within the same bed, was demonstrated. Thus, the need for a separate trace contaminant unit was eliminated resulting in an opportunity for significant weight savings. Unlike the current disposable charcoal bed, zeolites for trace contaminant removal are amenable to periodic regeneration.

  5. Powdered activated carbon coupled with enhanced coagulation for natural organic matter removal and disinfection by-product control: application in a Western Australian water treatment plant.

    PubMed

    Kristiana, Ina; Joll, Cynthia; Heitz, Anna

    2011-04-01

    The removal of organic precursors of disinfection by-products (DBPs), i.e. natural organic matter (NOM), prior to disinfection and distribution is considered as the most effective approach to minimise the formation of DBPs. This study investigated the impact of the addition of powdered activated carbon (PAC) to an enhanced coagulation treatment process at an existing water treatment plant on the efficiency of NOM removal, the disinfection behaviour of the treated water, and the water quality in the distribution system. This is the first comprehensive assessment of the efficacy of plant-scale application of PAC combined with enhanced coagulation on an Australian source water. As a result of the PAC addition, the removal of NOM improved by 70%, which led to a significant reduction (80-95%) in the formation of DBPs. The water quality in the distribution system also improved, indicated by lower concentrations of DBPs in the distribution system and better maintenance of disinfectant residual at the extremities of the distribution system. The efficacy of the PAC treatment for NOM removal was shown to be a function of the characteristics of the NOM and the quality of the source water, as well as the PAC dose. PAC treatment did not have the capacity to remove bromide ion, resulting in the formation of more brominated DBPs. Since brominated DBPs have been found to be more toxic than their chlorinated analogues, their preferential formation upon PAC addition must be considered, especially in source waters containing high concentrations of bromide. PMID:21353285

  6. Removal of methylene blue from aqueous solution by wood millet carbon optimization using response surface methodology

    NASA Astrophysics Data System (ADS)

    Ghaedi, Mehrorang; Kokhdan, Syamak Nasiri

    2015-02-01

    The use of cheep, non-toxic, safe and easily available adsorbent are efficient and recommended material and alternative to the current expensive substance for pollutant removal from wastewater. The activated carbon prepared from wood waste of local tree (millet) extensively was applied for quantitative removal of methylene blue (MB), while simply. It was used to re-used after heating and washing with alkaline solution of ethanol. This new adsorbent was characterized by using BET surface area measurement, FT-IR, pH determination at zero point of charge (pHZPC) and Boehm titration method. Response surface methodology (RSM) by at least the number of experiments main and interaction of experimental conditions such as pH of solution, contact time, initial dye concentration and adsorbent dosage was optimized and set as pH 7, contact time 18 min, initial dye concentration 20 ppm and 0.2 g of adsorbent. It was found that variable such as pH and amount of adsorbent as solely or combination effects seriously affect the removal percentage. The fitting experimental data with conventional models reveal the applicability of isotherm models Langmuir model for their well presentation and description and Kinetic real rate of adsorption at most conditions efficiently can be represented pseudo-second order, and intra-particle diffusion. It novel material is good candidate for removal of huge amount of MB (20 ppm) in short time (18 min) by consumption of small amount (0.2 g).

  7. Biologically active carbon filtration for haloacetic acid removal from swimming pool water.

    PubMed

    Tang, Hao L; Xie, Yuefeng F

    2016-01-15

    A biologically activate carbon (BAC) filter was continuously operated on site for the treatment of haloacetic acids (HAAs) in an outdoor swimming pool at an average empty bed contact time (EBCT) of 5.8 min. Results showed that BAC filtration was a viable technology for direct removal of HAAs from the pool water with a nominal efficiency of 57.7% by the filter while the chlorine residuals were 1.71 ± 0.90 mg/L during the study. THMs and TOC were not removed and thus were not considered as indicators of the effectiveness of BAC filtration. Increased EBCT in the range of 4.5 and 6.4 min led to improved HAA removal performance, which could be best fit by a logarithmic regression model. BAC filtration also affected the HAA speciation by removing more dichloroacetic acid (DCAA) than trichloroacetic acid (TCAA), resulting in a lower ratio of DCAA/TCAA in the filtered effluent. However, the observation of an overall constant ratio could be attributable to a complex formation and degradation mechanism occurring in swimming pools. PMID:26398451

  8. Development of Pressure Swing Adsorption Technology for Spacesuit Carbon Dioxide and Humidity Removal

    NASA Technical Reports Server (NTRS)

    Papale, William; Paul, Heather; Thomas, Gretchen

    2006-01-01

    Metabolically produced carbon dioxide (CO2) removal in spacesuit applications has traditionally been accomplished utilizing non-regenerative Lithium Hydroxide (LiOH) canisters. In recent years, regenerative Metal Oxide (MetOx) has been developed to replace the Extravehicular Mobility Unity (EMU) LiOH canister for extravehicular activity (EVA) missions in micro-gravity, however, MetOx may carry a significant weight burden for potential use in future Lunar or planetary EVA exploration missions. Additionally, both of these methods of CO2 removal have a finite capacity sized for the particular mission profile. Metabolically produced water vapor removal in spacesuits has historically been accomplished by a condensing heat exchanger within the ventilation process loop of the suit life support system. Advancements in solid amine technology employed in a pressure swing adsorption system have led to the possibility of combining both the CO2 and humidity control requirements into a single, lightweight device. Because the pressure swing adsorption system is regenerated to space vacuum or by an inert purge stream, the duration of an EVA mission may be extended significantly over currently employed technologies, while markedly reducing the overall subsystem weight compared to the combined weight of the condensing heat exchanger and current regenerative CO2 removal technology. This paper will provide and overview of ongoing development efforts evaluating the subsystem size required to manage anticipated metabolic CO2 and water vapor generation rates in a spacesuit environment.

  9. Effects of Vegetation Removal and Soil Disturbance on Soil Organic and Inorganic Carbon Dynamics in California Desert Ecosystems

    NASA Astrophysics Data System (ADS)

    Swanson, A. C.; Allen, E. B.; Allen, M. F.; Hernandez, R. R.

    2015-12-01

    Solar energy developments are projected to be deployed over desert wildland areas with deep soil inorganic carbon (SIC) deposits, which often involves elimination of deep-rooted vegetation. This land cover change may systemically alter SIC pools since respired CO2 is the carbon (C) source during SIC formation. We sought to understand how removal of creosote bush scrub affects soil C pools. We hypothesized that vegetation is important for maintaining SIC and soil organic C (SOC) pools and that disturbance to the vegetation and soil will change CO2 flux with increased losses from SIC. Soils were collected from sites that had intact creosote bush scrub habitat adjacent to disturbed, bare areas where the native vegetation had been previously removed. Samples were taken from beneath shrub canopies and interspaces in intact areas, and from random points in the disturbed area. Soils were analyzed for SIC, SOC, microbial and labile C, and δ13C. Soils were also incubated to determine the potential CO2 flux from disturbed and undisturbed soils along with the sources of CO2. Three replicates per soil underwent a control and water addition treatment and flux and δ13C of CO2 were measured continuously. Control replicates yielded no significant CO2 flux. CO2 flux from watered soils was higher beneath shrub canopy (18.57µmol g soil-1 day-1±1.86) than the interspace soils (0.86 µmol g soil-1 day-1±0.17). Soils collected from bare areas had an intermediate flux (5.41 µmol g soil-1 day-1±2.68 and 3.68 µmol g soil-1 day-1±0.85, respectively) lying between shrub canopy and interspace soils. There was no significant difference between the δ13C values of CO2 from shrub canopy and interspace soils, both of which had a very low δ13C values (-22.60‰±0.64 and -23.88‰±0.89, respectively), resembling that of organic C. However, the isotopic values of CO2 from disturbed soils were significantly higher (-16.68‰±1.36 and -15.22‰±2.12, respectively) suggesting that these

  10. Foliage plants for indoor removal of the primary combustion gases carbon monoxide and nitrogen dioxide

    NASA Technical Reports Server (NTRS)

    Wolverton, B. C.; Mcdonald, R. C.; Mesick, H. H.

    1985-01-01

    Foliage plants were evaluated for their ability to sorb carbon monoxide and nitrogen dioxide, the two primary gases produced during the combustion of fossil fuels and tobacco. The spider plant (Chlorophytum elatum var. vittatum) could sorb 2.86 micrograms CO/sq cm leaf surface in a 6 h photoperiod. The golden pothos (Scindapsus aureus) sorbed 0.98 micrograms CO/sq cm leaf surface in the same time period. In a system with the spider plant, greater than or equal to 99 percent of an initial concentration of 47 ppm NO2 could be removed in 6 h from a void volume of approximately 0.35 cu m. One spider plant potted in a 3.8 liter container can sorb 3300 micrograms CO and effect the removal of 8500 micrograms NO2/hour, recognizing the fact that a significant fraction of NO2 at high concentrations will be lost by surface sorption, dissolving in moisture, etc.

  11. Kupier prize lecture: Sources of solar-system carbon

    NASA Technical Reports Server (NTRS)

    Anders, Edward; Zinner, Ernst

    1994-01-01

    We have tried to deconvolve Solar-System carbon into its sources, on the basis of C-12/C-13 ratios (equivalent to R). Interstellar SiC in meteorites, representing greater than 4.6-Ga-old stardust from carbon stars, is isotopically heavier (bar R = 38 +/- 2) than Solar-System carbon (89), implying that the latter contains an additional, light component. A likely source are massive stars, mainly Type II supernovae and Wolf-Rayet stars, which, being O-rich, eject their C largely as CO rather than carbonaceous dust. The fraction of such light C in the Solar System depends on R(sub light) in the source. For R(sub light) = 180-1025 (as in 'Group 4' meteoritic graphite spherules, which apparently came from massive stars greater than 4.6 Ga ago), the fraction of light C is 0.79-0.61. Similar results are obtained for present-day data on red giants and interstellar gas. Although both have become enriched in C-13 due to galactic evolution (to bar-R = 20 and 57), the fraction of the light component in interstellar gas again is near 0.7. (Here bar R represents the mean of a mixture calculated via atom fractions; it is not identical to the arithmetic mean R). Interstellar graphite, unlike SiC, shows a large peak at R approximately equal 90, near the solar value. Although some of the grains may be of local origin, others show anomalies in other elements and hence are exotic. Microdiamonds, with R = 93, also are exotic on the basis of their Xe and N. Apparently R approximately 90 was a fairly common composition 4.6 Ga ago, of stars as well as the ISM.

  12. Kinetics of dechlorination by Dehalococcoides mccartyi using different carbon sources.

    PubMed

    Schneidewind, Uwe; Haest, Pieter Jan; Atashgahi, Siavash; Maphosa, Farai; Hamonts, Kelly; Maesen, Miranda; Calderer, Montse; Seuntjens, Piet; Smidt, Hauke; Springael, Dirk; Dejonghe, Winnie

    2014-02-01

    Stimulated anaerobic dechlorination is generally considered a valuable step for the remediation of aquifers polluted with chlorinated ethenes (CEs). Correct simulation and prediction of this process in situ, however, require good knowledge of the associated biological reactions. The aim of this study was to evaluate the dechlorination reaction in an aquifer contaminated with trichloroethene (TCE) and its daughter products, discharging into the Zenne River. Different carbon sources were used in batch cultures and these were related to the dechlorination reaction, together with the monitored biomarkers. Appropriate kinetic formulations were assessed. Reductive dechlorination of TCE took place only when external carbon sources were added to microcosms, and occurred concomitant with a pronounced increase in the Dehalococcoides mccartyi cell count as determined by 16S rRNA gene-targeted qPCR. This indicates that native dechlorinating bacteria are present in the aquifer of the Zenne site and that the oligotrophic nature of the aquifer prevents a complete degradation to ethene. The type of carbon source, the cell number of D. mccartyi or the reductive dehalogenase genes, however, did not unequivocally explain the observed differences in degradation rates or the extent of dechlorination. Neither first-order, Michaelis-Menten nor Monod kinetics could perfectly simulate the dechlorination reactions in TCE spiked microcosms. A sensitivity analysis indicated that the inclusion of donor limitation would not significantly enhance the simulations without a clear process understanding. Results point to the role of the supporting microbial community but it remains to be verified how the complexity of the microbial (inter)actions should be represented in a model framework. PMID:24275111

  13. Kinetics of dechlorination by Dehalococcoides mccartyi using different carbon sources

    NASA Astrophysics Data System (ADS)

    Schneidewind, Uwe; Haest, Pieter Jan; Atashgahi, Siavash; Maphosa, Farai; Hamonts, Kelly; Maesen, Miranda; Calderer, Montse; Seuntjens, Piet; Smidt, Hauke; Springael, Dirk; Dejonghe, Winnie

    2014-02-01

    Stimulated anaerobic dechlorination is generally considered a valuable step for the remediation of aquifers polluted with chlorinated ethenes (CEs). Correct simulation and prediction of this process in situ, however, require good knowledge of the associated biological reactions. The aim of this study was to evaluate the dechlorination reaction in an aquifer contaminated with trichloroethene (TCE) and its daughter products, discharging into the Zenne River. Different carbon sources were used in batch cultures and these were related to the dechlorination reaction, together with the monitored biomarkers. Appropriate kinetic formulations were assessed. Reductive dechlorination of TCE took place only when external carbon sources were added to microcosms, and occurred concomitant with a pronounced increase in the Dehalococcoides mccartyi cell count as determined by 16S rRNA gene-targeted qPCR. This indicates that native dechlorinating bacteria are present in the aquifer of the Zenne site and that the oligotrophic nature of the aquifer prevents a complete degradation to ethene. The type of carbon source, the cell number of D. mccartyi or the reductive dehalogenase genes, however, did not unequivocally explain the observed differences in degradation rates or the extent of dechlorination. Neither first-order, Michaelis-Menten nor Monod kinetics could perfectly simulate the dechlorination reactions in TCE spiked microcosms. A sensitivity analysis indicated that the inclusion of donor limitation would not significantly enhance the simulations without a clear process understanding. Results point to the role of the supporting microbial community but it remains to be verified how the complexity of the microbial (inter)actions should be represented in a model framework.

  14. Impact of exogenous organic carbon on the removal of chemicals of concern in the high rate nitrifying trickling filters.

    PubMed

    Mai, Lei; van den Akker, Ben; Du, Jun; Kookana, Rai S; Fallowfield, Howard

    2016-06-01

    The application of fixed bed high rate nitrifying trickling filters (NTFs) for the removal of track organic chemicals of concern (CoC) is less well known than their application to nutrient removal in water treatment. Particularly, the effect of exogenous organic carbon substrate (sucrose) loading on the performance of NTFs is not well understood. A laboratory-scale NTF system was operated in recirculation mode, with the objective of removing ammonia and CoC simultaneously. The efficiency of a high rate NTF for removal both of low concentration of ammonia (5 mg NH4-N L(-1)) and different concentrations of CoC in the presence of an exogenous organic carbon substrate (30 mg total organic carbon (TOC) L(-1)) was investigated. In the presence of exogenous organic carbon, the results demonstrated that the high rate NTF was able to successfully remove most of the CoCs investigated, with the removal ranging from 20.2% to 87.54%. High removal efficiencies were observed for acetaminophen (87.54%), bisphenol A (86.60%), trimethoprim (86.24%) and 17α-ethynylestradiol (80.60%). It was followed by the medium removal efficiency for N, N-diethyl-m-toluamide (61.31%) and atrazine (56.90%). In contrast, the removal of caffeine (28.43%) and benzotriazole (20.20%) was poorer in the presence of exogenous organic carbon. The removal efficiency for CoC was also compared with the results obtained in our previous study in the absence of exogenous organic carbon. The results showed that the addition of exogenous organic carbon was able to improve the removal of some of the CoC. Significant TOC percentage removals (45.68%-84.43%) and ammonia removal rate (mean value of 0.44 mg NH4-N L(-1) h(-1)) were also achieved in this study. The findings from this study provide valuable information for optimising the efficiency of high rate NTF for the removal of ammonia, CoC and TOC. PMID:26989940

  15. When Forest become carbon sources: Impact of herbivory on carbon balance

    NASA Astrophysics Data System (ADS)

    Schafer, K. V.; Clark, K. L.; Skowronski, N. S.

    2008-12-01

    Traditionally forests are thought to be carbon sinks and are becoming important trading commodities in the carbon trading markets. However, disturbances such as fire, hurricanes and herbivory can lead to forests being sources rather than sinks of carbon. Here, we investigate the carbon balance of an oak/pine forest in the New Jersey Pine Barrens under herbivory attack in summer 2007. Net primary productivity (NPP) was reduced to ca 70% of previous year NPP (535 g m-2 a-1 in 2006) and canopy net assimilation (AnC), as modeled with the Canopy Conductance Constrained Carbon Assimilation model (4C-A), was reduced to ca 65 % of previous year (1335 g m-2 a-1 in 2006) AnC or ca 1015 g C m-2 a-1. Although the trees were defoliated for only 15 % of the normal annual growing season, the impact amounted to ca 30 % of C accumulation loss when integrated over the year. Overall NPP in 2007 was ca 378 g C m-2 a-1 with 50 % of NPP being allocated to foliage production which constitutes a short term carbon pool. On an ecosystem level net ecosystem exchange amounted to a release of 293 g C m-2 a-1 thus becoming a carbon source over the course of the year rather than being a sink for C. The overall impact of the defoliation spanned 21% of upland forests (320 km2) in the New Jersey Pine Barrens thus representing a significant amount of overall C being emitted back to the atmosphere rather than being accumulated in the biosphere.

  16. North Siberian lakes: A methane source fueled by Pleistocene carbon

    SciTech Connect

    Zimov, S.A.; Davidov, S.P.; Prosiannikov, S.F.; Trumbore, S.

    1997-08-08

    The sizes of major sources and sinks of atmospheric methane (CH{sub 4}), an important greenhouse gas, are poorly known. CH{sub 4} from north Siberian lakes contributes {approximately}1.5 teragrams CH{sub 4} year{sup -1} to observed winter increases in atmospheric CH{sub 4} concentration at high northern latitudes. CH{sub 4} emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon.

  17. Effect of carbon to nitrogen (C:N) ratio on nitrogen removal from shrimp production waste water using sequencing batch reactor.

    PubMed

    Roy, Dhiriti; Hassan, Komi; Boopathy, Raj

    2010-10-01

    The United States Marine Shrimp Farming Program (USMSFP) introduced a new technology for shrimp farming called recirculating raceway system. This is a zero-water exchange system capable of producing high-density shrimp yields. However, this system produces wastewater characterized by high levels of ammonia, nitrite, and nitrate due to 40% protein diet for the shrimp at a high density of 1,000 shrimp per square meter. The high concentrations of nitrate and nitrite (greater than 25 ppm) are toxic to shrimp and cause high mortality. So treatment of this wastewater is imperative in order to make shrimp farming viable. One simple method of treating high-nitrogen wastewater is the use of a sequencing batch reactor (SBR). An SBR is a variation of the activated sludge process, which accomplishes many treatment events in a single reactor. Removal of ammonia and nitrate involved nitrification and denitrification reactions by operating the SBR aerobically and anaerobically in sequence. Initial SBR operation successfully removed ammonia, but nitrate concentrations were too high because of carbon limitation in the shrimp production wastewater. An optimization study revealed the optimum carbon to nitrogen (C:N) ratio of 10:1 for successful removal of all nitrogen species from the wastewater. The SBR operated with a C:N ratio of 10:1 with the addition of molasses as carbon source successfully removed 99% of ammonia, nitrate, and nitrite from the shrimp aquaculture wastewater within 9 days of operation. PMID:20835881

  18. Removal of 2-ClBP from soil-water system using activated carbon supported nanoscale zerovalent iron.

    PubMed

    Zhang, Wei; Yu, Tian; Han, Xiaolin; Ying, Weichi

    2016-09-01

    We explored the feasibility and removal mechanism of removing 2-chlorobiphenyl (2-ClBP) from soil-water system using granular activated carbon (GAC) impregnated with nanoscale zerovalent iron (reactive activated carbon or RAC). The RAC samples were successfully synthesized by the liquid precipitation method. The mesoporous GAC based RAC with low iron content (1.32%) exhibited higher 2-ClBP removal efficiency (54.6%) in the water phase. The result of Langmuir-Hinshelwood kinetic model implied that the different molecular structures between 2-ClBP and trichloroethylene (TCE) resulted in more difference in dechlorination reaction rates on RAC than adsorption capacities. Compared to removing 2-ClBP in the water phase, RAC removed the 2-ClBP more slowly in the soil phase due to the significant external mass transfer resistance. However, in the soil phase, a better removal capacity of RAC was observed than its base GAC because the chemical dechlorination played a more important role in total removal process for 2-ClBP. This important result verified the effectiveness of RAC for removing 2-ClBP in the soil phase. Although reducing the total RAC removal rate of 2-ClBP, soil organic matter (SOM), especially the soft carbon, also served as an electron transfer medium to promote the dechlorination of 2-ClBP in the long term. PMID:27593281

  19. Intraoperative Extracorporeal Carbon Dioxide Removal During Apneic Oxygenation with an EZ-Blocker in Tracheal Surgery.

    PubMed

    Rispoli, Marco; Nespoli, Moana Rossella; Mattiacci, Dario Maria; Esposito, Marianna; Corcione, Antonio; Buono, Salvatore

    2016-06-01

    Tracheal surgery requires continued innovation to manage the anesthetic during an open airway phase. A common approach is apneic oxygenation with continuous oxygen flow, but the lack of effective ventilation causes hypercapnia, with respiratory acidosis. We used extracorporeal carbon dioxide removal for intraoperative decapneization during apneic oxygenation in a 64-year-old woman who was scheduled for tracheal surgery because of tracheal stenosis caused by long-term intubation. Our findings demonstrate that even after 40 minutes of total apnea, using an EZ-blocker for oxygenation and external decapneization, hemodynamic and gas exchange variables never demonstrated any dangerous alterations. PMID:27075426

  20. The use of capacitive deionization with carbon aerogel electrodes to remove inorganic contaminants from water

    SciTech Connect

    Farmer, J.C.; Fix, D.V.; Mack, G.V.; Pekala, R.W.; Poco, J.F.

    1995-02-17

    The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated for the first time. Unlike ion exchange, one of the more conventional deionization processes, no chemicals were required for regeneration of the system. Electricity was used instead. Water with various anions and cations was pumped through the electrochemical cell. After polarization, ions were electrostatically removed from the water and held in the electric double layers formed at electrode surfaces. The water leaving the cell was purified, as desired.

  1. A regenerative process for carbon dioxide removal and hydrogen production in IGCC

    NASA Astrophysics Data System (ADS)

    Hassanzadeh Khayyat, Armin

    Advanced power generation technologies, such as Integrated Gasification-Combined Cycles (IGCC) processes, are among the leading contenders for power generation conversion because of their significantly higher efficiencies and potential environmental advantages, compared to conventional coal combustion processes. Although the increased in efficiency in the IGCC processes will reduce the emissions of carbon dioxide per unit of power generated, further reduction in CO2 emissions is crucial due to enforcement of green house gases (GHG) regulations. In IGCC processes to avoid efficiency losses, it is desirable to remove CO2 in the temperature range of 300° to 500°C, which makes regenerable MgO-based sorbents ideal for such operations. In this temperature range, CO2 removal results in the shifting of the water-gas shift (WGS) reaction towards significant reduction in carbon monoxide (CO), and enhancement in hydrogen production. However, regenerable, reactive and attrition resistant sorbents are required for such application. In this work, a highly reactive and attrition resistant regenerable MgO-based sorbent is prepared through dolomite modification, which can simultaneously remove carbon dioxide and enhance hydrogen production in a single reactor. The results of the experimental tests conducted in High-Pressure Thermogravimetric Analyzer (HP-TGA) and high-pressure packed-bed units indicate that in the temperature range of 300° to 500°C at 20 atm more than 95 molar percent of CO2 can be removed from the simulated coal gas, and the hydrogen concentration can be increased to above 70 percent. However, a declining trend is observed in the capacity of the sorbent exposed to long-term durability analysis, which appears to level off after about 20 cycles. Based on the physical and chemical analysis of the sorbent, a two-zone expanding grain model was applied to obtain an excellent fit to the carbonation reaction rate data at various operating conditions. The modeling

  2. The selective removal of metallic carbon nanotubes from As-grown arrays on insulating substrates

    NASA Astrophysics Data System (ADS)

    Tunnell, Andrew; Ballarotto, Vincent; Cumings, John

    2012-11-01

    We present a method of selectively removing metallic single-walled carbon nanotubes (SWCNTs) from as-grown arrays on quartz substrates. The process utilizes an external silicon piece as a temporary global top gate to increase the resistance of the semiconducting SWCNTs while current is passed through the metallic SWCNTs, causing electrical breakdown through joule heating. The resulting SWCNT field-effect transistors (FETs) consistently produce on/off current ratios greater than 1000. Additionally, we find that the high frequency parasitic losses between 1 GHz and 6 GHz on the completed SWCNT FETs are significantly lower than on comparable SWCNT FETs fabricated on silicon substrates.

  3. Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels.

    PubMed

    Sánchez-Polo, M; Rivera-Utrilla, J; Salhi, E; von Gunten, U

    2006-08-01

    The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)carbonization and activation processes increased the adsorptive capacity of the aerogel sample. However, results showed that the adsorption capacity of the aerogel samples studied was considerably lower in water from Lake Zurich. Results showed X(0.02) (amount adsorbed to initial breakthrough) values of 0.1 and 4.3 mg/g for chloride anion and dissolved organic carbon (DOC), respectively, during bromide adsorption process in water from Lake Zurich

  4. Removal of р-nitrophenol from aqueous solution by magnetically modified activated carbon

    NASA Astrophysics Data System (ADS)

    Han, Shuai; Zhao, Feng; Sun, Jian; Wang, Bin; Wei, Rongyan; Yan, Shiqiang

    2013-09-01

    Activated carbon was modified with γ-Fe2O3 nanoparticles, using the chemical co-precipitation technique and the carboxylic acid vapor treatment technique. Two magnetic composites were characterized and compared by Fourier Transform Infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry and nitrogen adsorption-desorption. Then the two materials were used to remove p-nitrophenol in water. The equilibrium data revealed that the Langmuir isotherm was better in fitting the experiment result than the Freundlich isotherm, and the sorption capacity of the nanocomposite made by the chemical co-precipitation technique was higher than that of the other one. We suggest that the chemical co-precipitation technique is a more efficient and practical method to produce magnetically modified activated carbon.

  5. Selective adsorption for removal of nitrogen compounds from hydrocarbon streams over carbon-based adsorbents

    NASA Astrophysics Data System (ADS)

    Almarri, Masoud S.

    desulfurization of model diesel fuel, which contains equimolar concentrations of nitrogen (i.e., quinoline and indole), sulfur (i.e., dibenzothiophene and 4,6-dimethyldibenzothiophene), and aromatic compounds (naphthalene, 1-methylnaphthalene, and fluorene), was examined. The results revealed that when both nitrogen and sulfur compounds coexist in the fuel, the type and density of oxygen functional groups on the surface of the activated carbon are crucial for selective adsorption of nitrogen compounds but have negligible positive effects for sulfur removal. The adsorption of quinoline and indole is largely governed by specific interactions. There is enough evidence to support the importance of dipole--dipole and acid-base-specific interactions for the adsorption of both quinoline and indole. Modified carbon is a promising material for the efficient removal of the nitrogen compounds from light cycle oil (LCO). Adsorptive denitrogenation of LCO significantly improved the hydrodesulfurization (HDS) performance, especially for the removal of the refractory sulfur compounds such as 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. An essential factor in applying activated carbon for adsorptive denitrogenation and desulfurization of liquid hydrocarbon streams is regeneration after saturation. The regeneration method of the saturated adsorbents consisted of toluene washing followed by heating to remove the remaining toluene. The results show that the spent activated carbon can be regenerated to completely recover the adsorption capacity. The high capacity and selectivity of activated carbon for nitrogen compounds, along with their ability to be regenerated, indicate that activated carbon is a promising adsorbent for the deep denitrogenation of liquid hydrocarbon streams.

  6. Carbon and nitrogen removal and enhanced methane production in a microbial electrolysis cell.

    PubMed

    Villano, Marianna; Scardala, Stefano; Aulenta, Federico; Majone, Mauro

    2013-02-01

    The anode of a two-chamber methane-producing microbial electrolysis cell (MEC) was poised at +0.200V vs. the standard hydrogen electrode (SHE) and continuously fed (1.08gCOD/Ld) with acetate in anaerobic mineral medium. A gas mixture (carbon dioxide 30vol.% in N(2)) was continuously added to the cathode for both pH control and carbonate supply. At the anode, 94% of the influent acetate was removed, mostly through anaerobic oxidation (91% coulombic efficiency); the resulting electric current was mainly recovered as methane (79% cathode capture efficiency). Low biomass growth was observed at the anode and ammonium was transferred through the cationic membrane and concentrated at the cathode. These findings suggest that the MEC can be used for the treatment of low-strength wastewater, with good energy efficiency and low sludge production. PMID:23313682

  7. Overview of International Space Station Carbon Dioxide Removal Assembly On-Orbit Operations and Performance

    NASA Technical Reports Server (NTRS)

    Matty, Christopher M.

    2013-01-01

    Controlling Carbon Dioxide (CO2) partial pressure in the habitable vehicle environment is a critical part of operations on the International Space Station (ISS). On the United States segment of ISS, CO2 levels are primarily controlled by the Carbon Dioxide Removal Assembly (CDRA). There are two CDRAs on ISS; one in the United States Laboratory module, and one in the Node3 module. CDRA has been through several significant operational issues, performance issues and subsequent re-design of various components, primarily involving the Desiccant Adsorbent Bed (DAB) assembly and Air Selector Valves (ASV). This paper will focus on significant operational and performance issues experienced by the CDRA team from 2008-2012.

  8. Hexavalent chromium [Cr(VI)] removal by acid modified waste activated carbons.

    PubMed

    Ghosh, Pranab Kumar

    2009-11-15

    Fresh activated carbon (AC) and waste activated carbon (WAC) were pretreated by heating with mineral acids (sulfuric acid and nitric acid) at high temperature to prepare several grades of adsorbents to evaluate their performance on Cr(VI) removal from aqueous phase. Effects of temperature, agitation speed and pH were tested, and optimum conditions were evaluated. Kinetic study was performed under optimum conditions with several grades of modified adsorbents to know the rates of adsorption. Batch adsorption equilibrium data followed both, Freuindlich and Langmuir isotherms. Maximum adsorption capacity (q(max)) of the selected adsorbents treated with sulfuric acid (MWAC 1) and nitric acid (MWAC 2), calculated from Langmuir isotherm are 7.485 and 10.929 mg/g, respectively. Nitric acid treated adsorbent (MWAC 2) was used for column study to determine the constants of bed depth service time (BDST) model for adsorption column design. PMID:19553008

  9. Soil organic carbon dust emission: an omitted global source of atmospheric CO2?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO2) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and tr...

  10. The role of carbon dust emission as a global source of atmospheric CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO2) budget, because wind erosion contributes to the C cycle by selectively removing4 SOC from vast areas and ...

  11. Quantification of carbon sources for isoprene emission in poplar leaves

    NASA Astrophysics Data System (ADS)

    Kreutzwieseer, J.; Graus, M.; Schnitzler, J. P.; Heizmann, U.; Rennenberg, H.; Hansel, A.

    2003-12-01

    Isoprene is the most abundant volatile organic compound emitted by plants and in particular by trees. Current interest in understanding its biosynthesis in chloroplasts is forced by the important role isoprene plays in atmospheric chemistry. Leaf isoprene formation is closely linked to photosynthesis by a dynamic use of recently fixed photosynthetic precursors in the chloroplast. Under steady state conditions in [13C]CO2 atmosphere approximately 75 % of isoprene became labeled within minutes. The source of unlabeled C is suggested to be of extra-chloroplastidic and/or from starch degradation. In order to test whether these alternative carbon sources - leaf internal C-pools and xylem-transported carbohydrates, contribute to leaf isoprene formation in poplar (Populus tremula x P. alba) on-line proton-transfer-reaction-mass spectrometry (PTR-MS) was used to follow 13C-labeling kinetics.

  12. Removal of highly polar micropollutants from wastewater by powdered activated carbon.

    PubMed

    Kovalova, Lubomira; Knappe, Detlef R U; Lehnberg, Kai; Kazner, Christian; Hollender, Juliane

    2013-06-01

    Due to concerns about ecotoxicological effects of pharmaceuticals and other micropollutants released from wastewater treatment plants, activated carbon adsorption is one of the few processes to effectively reduce the concentrations of micropollutants in wastewater. Although aimed mainly at apolar compounds, polar compounds are also simultaneously removed to a certain extent, which has rarely been studied before. In this study, adsorption isotherm and batch kinetic data were collected with two powdered activated carbons (PACs) to assess the removal of the polar pharmaceuticals 5-fluorouracil (5-Fu) and cytarabine (CytR) from ultrapure water and wastewater treatment plant effluent. At pH 7.8, single-solute adsorption isotherm data for the weak acid 5-Fu and the weak base CytR showed that their adsorption capacities were about 1 order of magnitude lower than those of the less polar endocrine disrupting chemicals bisphenol A (BPA) and 17-α-ethinylestradiol (EE2). To remove 90 % of the adsorbate from a single-solute solution 14, 18, 70, and 87 mg L(-1) of HOK Super is required for EE2, BPA, CytR, and 5-Fu, respectively. Effects of solution pH, ionic strength, temperature, and effluent organic matter (EfOM) on 5-Fu and CytR adsorption were evaluated for one PAC. Among the studied factors, the presence of EfOM had the highest effect, due to a strong competition on 5-Fu and CytR adsorption. Adsorption isotherm and kinetic data and their modeling with a homogeneous surface diffusion model showed that removal percentage in the presence of EfOM was independent on the initial concentration of the ionizable compounds 5-Fu and CytR. These results are similar to neutral organic compounds in the presence of natural organic matter. Overall, results showed that PAC doses sufficient to remove >90 % of apolar adsorbates were able to remove no more than 50 % of the polar adsorbates 5-Fu and CytR and that the contact time is a critical parameter. PMID:23299971

  13. Potential application of activated carbon from maize tassel for the removal of heavy metals in water

    NASA Astrophysics Data System (ADS)

    Olorundare, O. F.; Krause, R. W. M.; Okonkwo, J. O.; Mamba, B. B.

    Water-pollution problems worldwide have led to an acute shortage of clean and pure water for both domestic and human consumption. Various technologies and techniques are available for water treatment which includes the use of activated carbon. In this study activated carbons used for the removal of lead (II) ions from water samples were prepared from maize tassels (an agricultural waste residue) which were modified using physical and chemical activation. In the physical activation CO2 was used as the activating agent, while in chemical activation H3PO4 with an impregnation ratio ranging from 1 to 4 was employed. The maize tassel was pyrolysed at different temperatures ranging from 300 °C to 700 °C in an inert atmosphere for a period of 60 min and activated at 700 °C for 30 min. The effects of activation temperature, impregnation ratio and duration were examined. The resultant modified tassels were characterised by measuring their particle-size distribution, porosities, pore volume, and pore-size distribution using scanning electron microscopy (SEM). The activated carbon produced by chemical activation had the highest BET surface area ranging from 623 m2 g-1 to 1 262 m2 g-1. The surface chemistry characteristics of the modified tassels were determined by FT-IR spectroscopy and Boehm’s titration method. The experimental data proved that properties of activated carbon depend on final temperature of the process, impregnation ratio and duration of the treatment at final temperature. The adsorption studies showed that chemically prepared activated carbon performed better than physically prepared activated carbon.

  14. Partitioning and removal of dioxin-like congeners in flue gases treated with activated carbon adsorption.

    PubMed

    Chi, Kai Hsien; Chang, Shu Hao; Huang, Chia Hua; Huang, Hung Chi; Chang, Moo Been

    2006-08-01

    Activated carbon adsorption is commonly used to control dioxin-like congener (PCDD/Fs and PCBs) emissions. Partitioning of PCDD/Fs and PCBs between vapor and solid phases and their removal efficiencies achieved with existing air pollution control devices (APCDs) at a large-scale municipal waste incinerator (MWI) and an industrial waste incinerator (IWI) are evaluated via intensive stack sampling and analysis. Those two facilities investigated are equipped with activated carbon injection (ACI) with bag filter (BF) and fixed activated carbon bed (FACB) as major PCDD/F control devices, respectively. Average PCDD/F and PCB concentrations of stack gas with ACI+BF as APCDs are 0.031 and 0.006ng-TEQ/Nm(3), and that achieved with FACB are 1.74 and 0.19ng-TEQ/Nm(3) in MWI and IWI, respectively. The results show that FACB could reduce vapor-phase PCDD/Fs and PCBs concentrations in flue gas, while the ACI+BF can effectively adsorb the vapor-phase dioxin-like congener and collect the solid-phase PCDD/Fs and PCBs in the meantime. Additionally, the results of the pilot-scale adsorption system (PAS) experimentation indicate that each gram activated carbon adsorbs 105-115ng-PCDD/Fs and each surface area (m(2)) of activated carbon adsorbs 10-25ng-PCDD/Fs. Based on the results of PAS experimentation, this study confirms that the surface area of mesopore+macropore (20-200A) of the activated carbon is a critical factor affecting PCDD/F adsorption capacity. PMID:16488462

  15. Ag-doped carbon aerogels for removing halide ions in water treatment.

    PubMed

    Sánchez-Polo, M; Rivera-Utrilla, J; Salhi, E; von Gunten, U

    2007-03-01

    The objective of this study was to analyze the efficiency of silver(Ag)-doped carbon aerogels for the removal of bromide (Br(-)) and iodide (I(-)) from drinking waters. Textural characterization of Ag-doped aerogels showed that an increase in the Ag dose added during the preparation process produced: (i) a reduction in the surface area (S(BET)) and (ii) an increase in mesopore (V(2)) and macropore (V(3)) volumes. Chemical characterization of the materials revealed an acidic surface (pH of point of zero charge, pH(PZC)=4.5, O(surface)=20%). The oxidation state of Ag was +1 and the surface concentration of this element ranged from 4% to 10%. The adsorption capacity (X(m)) and affinity of adsorbent (BX(m)) increased with a reduction in the radius of the halogenide. Furthermore, an increase in the adsorption capacity was observed with higher Ag concentrations on the aerogel surface. The high adsorption capacity of the aerogel may be due to the presence of Ag(I) on its surface, with the formation of the corresponding Ag halides. Our observations indicate that the halogenides adsorption on commercial activated carbon (Sorbo-Norit) is much lower than that of the Ag-doped carbon aerogels. The presence of chloride and natural organic matter (NOM) in the medium reduced the adsorption capacity of Br(-) and I(-) on Ag carbon aerogels. PMID:16970974

  16. Passive CO{sub 2} removal using a carbon fiber composite molecular sieve

    SciTech Connect

    Burchell, T.D.; Judkins, R.R.

    1995-12-01

    Manufacture and characterization of a carbon fiber composite molecular sieve (CFCMS), and its efficacy as a CO{sub 2} gas adsorbent are reported. The CFCMS consists of an isotropic pitch derived carbon fiber and a phenolic resin derived carbon binder. Activation (selective gasification) of the CFCMS creates microporosity in the carbon fibers, yielding high micropore volumes (>0.5 cm{sup 3}/g) and BET surface areas (>1000 m{sup 2}/g). Moreover, the CFCMS material is a rigid, strong, monolith with an open structure that allows the free-flow of fluids through the material. This combination of properties provides an adsorbent material that has several distinct advantages over granular adsorbents in gas separation systems such as pressure swing adsorption (PSA) units. The results of our initial evaluations of the CO{sub 2} adsorption capacity and kinetics of CFCMS are reported. The room temperature CO{sub 2} adsorption capacity of CFCMS is >120 mg of CO{sub 2} per g of CFCMS. A proposed project is described that targets the development, over a three-year period, of a demonstration separation system based on CFCMS for the removal of CO{sub 2} from a flue gas slip stream at a coal-fired power plant. The proposed program would be conducted jointly with industrial and utility partners.

  17. The removal of uranium (VI) from aqueous solutions onto activated carbon developed from grinded used tire.

    PubMed

    Belgacem, Ahmed; Rebiai, Rachid; Hadoun, Hocine; Khemaissia, Sihem; Belmedani, Mohamed

    2014-01-01

    In this study, activated carbon was prepared from waste tire by KOH chemical activation. The pore properties including the BET surface area, pore volume, pore size distribution, and average pore diameter were characterized. BET surface area of the activated carbon was determined as 558 m(2)/g. The adsorption of uranium ions from the aqueous solution using this activated carbon has been investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied by a batch method. The optimum pH for adsorption was found to be 3. The removal efficiency has also been determined for the adsorption system as a function of initial concentration. The experimental results were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. A comparison of best-fitting was performed using the coefficient of correlation and the Langmuir isotherm was found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of uranium ions onto waste tire activated carbon was 158.73 mg/g. The thermodynamic equilibrium constant and the Gibbs free energy were determined and results indicated the spontaneous nature of the adsorption process. Kinetics data were best described by pseudo-second-order model. PMID:23821251

  18. Ammonia removal using activated carbons: effect of the surface chemistry in dry and moist conditions.

    PubMed

    Gonçalves, Maraisa; Sánchez-García, Laura; Oliveira Jardim, Erika de; Silvestre-Albero, Joaquín; Rodríguez-Reinoso, Francisco

    2011-12-15

    The effect of surface chemistry (nature and amount of oxygen groups) in the removal of ammonia was studied using a modified resin-based activated carbon. NH(3) breakthrough column experiments show that the modification of the original activated carbon with nitric acid, that is, the incorporation of oxygen surface groups, highly improves the adsorption behavior at room temperature. Apparently, there is a linear relationship between the total adsorption capacity and the amount of the more acidic and less stable oxygen surface groups. Similar experiments using moist air clearly show that the effect of humidity highly depends on the surface chemistry of the carbon used. Moisture highly improves the adsorption behavior for samples with a low concentration of oxygen functionalities, probably due to the preferential adsorption of ammonia via dissolution into water. On the contrary, moisture exhibits a small effect on samples with a rich surface chemistry due to the preferential adsorption pathway via Brønsted and Lewis acid centers from the carbon surface. FTIR analyses of the exhausted oxidized samples confirm both the formation of NH(4)(+) species interacting with the Brønsted acid sites, together with the presence of NH(3) species coordinated, through the lone pair electron, to Lewis acid sites on the graphene layers. PMID:22049916

  19. Increased fermentation activity and persistent methanogenesis in a model aquifer system following source removal of an ethanol blend release.

    PubMed

    Ma, Jie; Rixey, William G; Alvarez, Pedro J J

    2015-01-01

    The increased probability of groundwater contamination by ethanol-blended fuel calls for improved understanding of how remediation efforts affect the fate and transport of constituents of concern, including the generation and fate of fermentation byproducts. A pilot-scale (8 m³) model aquifer was used to investigate changes in the concentrations of ethanol and its metabolites (methane and volatile fatty acids) after removal of the contamination source. Following the shut-off of a continuous release of a dissolved ethanol blend (10% v:v ethanol, 50 mg/L benzene, and 50 mg/L toluene), fermentation activity was surprisingly stimulated and the concentrations of ethanol metabolites increased. A microcosm experiment showed that this result was due to a decrease in the dissolved ethanol concentration below its toxicity threshold (∼2000 mg/L for this system). Methane generation (>1.5 mg/L of dissolved methane) persisted for more than 100 days after the disappearance of ethanol, despite clean air-saturated water flowing continuously through the tank at a relative high seepage velocity (0.76 m/day). Quantitative real-time PCR showed that functional genes associated with methane metabolism (mcrA for methanogenesis and pmoA for methanotrophy) also persisted in the aquifer material. Persistent methanogenesis was apparently due to the anaerobic degradation of soil-bound organic carbon (e.g., biomass grown on ethanol and other substrates). Overall, this study reflects the complex plume dynamics following source removal, and suggests that monitoring for increases in the concentration of ethanol metabolites that impact groundwater quality should be considered. PMID:25462754

  20. Prediction of powdered activated carbon doses for 2-MIB removal in drinking water treatment using a simplified HSDM approach.

    PubMed

    Yu, Jianwei; Yang, Fong-Chen; Hung, Wei-Nung; Liu, Chia-Ling; Yang, Min; Lin, Tsair-Fuh

    2016-08-01

    The addition of powdered activated carbon (PAC) is an effective measure to cope with seasonal taste and odor (T&O) problems caused by 2-methylisoborneol (2-MIB) and trans-1, 10-dimethyl-trans-9-decalol (geosmin) in drinking water. Some T&O problems are episodic in nature, and generally require rapid responses. This paper proposed a simplified approach for the application of the homogenous surface diffusion model (HSDM) to predict the appropriate PAC doses for the removal of 2-MIB. Equilibrium and kinetic experiments were performed for 2-MIB adsorption onto five PACs in three source waters. The simplified HSDM approach was compared with the experimental data, by assigning the Freundlich 1/n value in the range of 0.1-1.0 and obtaining the Freundlich equilibrium parameter K value through a 6-hr adsorption kinetic test. The model describes the kinetic adsorption data very well for all of the tested PACs in different source waters. The results were validated using the data obtained from one full scale water treatment plant, and the differences between the predicted and observed results were within 10% range. This simplified HSDM approach may be applied for the rapid determination of PAC doses for water treatment plants when faced with 2-MIB episodes in source waters. PMID:27186686

  1. Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators

    SciTech Connect

    Fink, R. L.; Jiang, N.; Thuesen, L.; Leung, K. N.; Antolak, A. J.

    2009-03-10

    Field ionization uses high electric fields to cause the ionization and emission of ions from the surface of a sharp electrode. We are developing a novel field ionization neutron generator using carbon nanotubes (CNT) to produce the deuterium ion current. The generator consists of three major components: a deuterium ion source made of carbon nanotubes, a smooth negatively-biased target electrode, and a secondary electron suppression system. When a negative high voltage is applied on the target electrode, a high gradient electric field is formed at the tips of the carbon nanotubes. This field is sufficiently strong to create deuterium (D) ions at or near the nanotubes which are accelerated to the target causing D-D reactions to occur and the production of neutrons. A cross magnetic field is used to suppress secondary emission electrons generated on the target surface. We have demonstrated field ionization currents of 70 nA (1 {mu}A/cm{sup 2}) at hydrogen gas pressure of 10 mTorr. We have found that the current scales proportionally with CNT area and also with the gas pressure in the range of 1 mTorr to 10 mTorr. We have demonstrated pulse cut-off times as short as 2 {mu}sec. Finally, we have shown the feasibility of generating neutrons using deuterium gas.

  2. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact (BBCSI) Study was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement site in Barrow, AK. The carbonaceous component was characterized via measurement of the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the particulate matter, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine (PM2.5) and 49 coarse (PM10) particulate matter fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the BBCSI used standard Tisch hi-vol motors which have a known lifetime of ~1 month under constant use; this necessitated monthly maintenance and it is suggested that the motors be upgraded to industrial blowers for future deployment in the Arctic. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric particulate matter samples from Barrow, AK from July 2012 to June 2013. Preliminary analysis of the organic and black carbon concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer.

  3. Ammonia removal in the carbon contactor of a hybrid membrane process.

    PubMed

    Stoquart, Céline; Servais, Pierre; Barbeau, Benoit

    2014-12-15

    The hybrid membrane process (HMP) coupling powdered activated carbon (PAC) and low-pressure membrane filtration is emerging as a promising new option to remove dissolved contaminants from drinking water. Yet, defining optimal HMP operating conditions has not been confirmed. In this study, ammonia removal occurring in the PAC contactor of an HMP was simulated at lab-scale. Kinetics were monitored using three PAC concentrations (1-5-10 g L(-1)), three PAC ages (0-10-60 days), two temperatures (7-22 °C), in ambient influent condition (100 μg N-NH4 L(-1)) as well as with a simulated peak pollution scenario (1000 μg N-NH4L(-1)). The following conclusions were drawn: i) Using a colonized PAC in the HMP is essential to reach complete ammonia removal, ii) an older PAC offers a higher resilience to temperature decrease as well as lower operating costs; ii) PAC concentration inside the HMP reactor is not a key operating parameter as under the conditions tested, PAC colonization was not limited by the available surface; iii) ammonia flux limited biomass growth and iv) hydraulic retention time was a critical parameter. In the case of a peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed reaching a 50% ammonia removal. Finally, a kinetic model based on these experiments is proposed to predict ammonia removal occurring in the PAC reactor of the HMP. The model determines the relative importance of the adsorption and biological oxidation of ammonia on colonized PAC, and demonstrates the combined role of nitrification and residual adsorption capacity of colonized PAC. PMID:25459222

  4. Performance evaluation of powdered activated carbon for removing 28 types of antibiotics from water.

    PubMed

    Zhang, Xinbo; Guo, Wenshan; Ngo, Huu Hao; Wen, Haitao; Li, Nan; Wu, Wei

    2016-05-01

    Currently, the occurrence and fate of antibiotics in the aquatic environment has become a very serious problem in that they can potentially and irreversibly damage the ecosystem and human health. For this reason, interest has increased in developing strategies to remove antibiotics from water. This study evaluated the performance of powdered activated carbon (PAC) in removing from water 6 representative groups of 28 antibiotics, namely Tetracyclines (TCs), Macrolides (MCs), Chloramphenicols (CPs), Penicillins (PNs), Sulfonamides (SAs) and Quinolones (QNs). Results indicate that PAC demonstrated superior adsorption capacity for all selected antibiotics. The removal efficiency was up to 99.9% in deionized water and 99.6% in surface water at the optimum conditions with PAC dosage of 20 mg/L and contact time of 120 min. According to the Freundlich model's adsorption isotherm, the values of n varied among these antibiotics and most were less than 1, suggesting that the adsorption of antibiotics onto PAC was nonlinear. Adsorption of antibiotics followed well the pseudo-second-order kinetic model (R(2) = 0.99). Analysis using the Weber-Morris model revealed that the intra-particle diffusion was not the only rate-controlling step. Overall, the findings in this study confirm that PAC is a feasible and viable option for removing antibiotics from water in terms of water quality improvement and urgent antibiotics pollution control. Further research is essential on the following subjects: (i) removing more types of antibiotics by PAC; (ii) the adsorption process; and (iii) the mechanism of the competitive adsorption existing between natural organic matters (NOMs) and antibiotics. PMID:26946168

  5. International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA) Desiccant/Adsorbent Bed (DAB) Orbital Replacement Unit (ORU) Redesign

    NASA Technical Reports Server (NTRS)

    Reysa, Richard P.; Lumpkin, John P.; Sherif, Dian El; Kay, Robert; Williams, David E.

    2007-01-01

    The Carbon Dioxide Removal Assembly (CDRA) is a part of the International Space Station (ISS) Environmental Control and Life Support (ECLS) system. The CDRA provides carbon dioxide (CO2) removal from the ISS on-orbit modules. Currently, the CDRA is the secondary removal system on the ISS, with the primary system being the Russian Vozdukh. Within the CDRA are two desiccant/adsorbent beds (DAB), which perform the carbon dioxide removal function. The DAB adsorbent containment approach required improvements with respect to adsorbent containment. These improvements were implemented through a redesign program and have been implemented on units returning from orbit. This paper presents a DAB design modification implementation description, a hardware performance comparison between the unmodified and modified DAB configurations, and a description of the modified DAB hardware implementation into the on-orbit CDRA.

  6. Preparation and Physicochemical Evaluation of Controlled-release Carbon Source Tablet for Groundwater in situ Denitrification

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kang, J. H.; Yeum, Y.; Han, K. J.; Kim, D. W.; Park, C. W.

    2015-12-01

    Nitric nitrogen could be the one of typical pollution source such asNO3-through domestic sewage, livestock and agricultural wastewater. Resident microflorain aquifer has known to remove the nitric nitrogen spontaneously following the denitration process with the carbon source (CS) as reactant. However, it could be reacted very slowly with the rack of CS and there have been some studies for controlled addition of CS (Ref #1-3). The aim of this study was to prepare the controlled-release carbon source (CR-CS) tablet and to evaluate in vitro release profile for groundwater in situ denitrification. CR-CS tablet could be manufactured by direct compression method using hydraulic laboratory press (Caver® 3850) with 8 mm rounded concave punch/ die.Seven kinds of CR-CS tablet were prepared to determine the nature of the additives and their ratio such as sodium silicate, dicalcium phosphate, bentonite and sand#8.For each formulation, the LOD% and flowability of pre-mixed powders and the hardness of compressed tablets were analyzed. In vitro release study was performed to confirm the dissolution profiles following the USP Apparatus 2 method with Distilled water of 900mL, 20 °C. As a result, for each lubricated powders, they were compared in terms of ability to give an acceptable dry pre-mixed powder for tableting process. The hardness of the compressed tablets is acceptable whatever the formulations tested. After in vitro release study, it could confirm that the different formulations of CR-CS tablet have a various release rate patterns, which could release 100% at 3 hrs, 6 hrs and 12 hrs. The in vitro dissolution profiles were in good correlation of Higuchi release kinetic model. In conclusion, this study could be used as a background for development and evaluation of the controlled-release carbon source (CR-CS) tablet for the purification of groundwater following the in situ denitrification.

  7. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact campaign was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility site in Barrow, Alaska. The carbonaceous component was characterized by measuring the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the PM, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine PM fractions (PM2.5) and 49 coarse (PM10) PM fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the Barrow Black Carbon Source and Impact (BBCSI) study used standard Tisch “hi-vol” motors that have a known lifetime of approximately 1 month under constant use; this necessitated monthly maintenance, and it is suggested that, for future deployment in the Arctic, the motors be upgraded to industrial blowers. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric PM samples from Barrow, Alaska, from July 2012 to June 2013. Preliminary analysis of the OC and BC concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer. However, the annual OC concentrations had a very different seasonal pattern with the highest concentrations during the summer, lowest concentrations during the fall, and increased concentrations during the winter and spring (Figure 1).

  8. Muscle and eye movement artifact removal prior to EEG source localization.

    PubMed

    Hallez, Hans; Vergult, Anneleen; Phlypo, Ronald; Van Hese, Peter; De Clercq, Wim; D'Asseler, Yves; Van de Walle, Rik; Vanrumste, Bart; Van Paesschen, Wim; Van Huffel, Sabine; Lemahieu, Ignace

    2006-01-01

    Muscle and eye movement artifacts are very prominent in the ictal EEG of patients suffering from epilepsy, thus making the dipole localization of ictal activity very unreliable. Recently, two techniques (BSS-CCA and pSVD) were developed to remove those artifacts. The purpose of this study is to assess whether the removal of muscle and eye movement artifacts improves the EEG dipole source localization. We used a total of 8 EEG fragments, each from another patient, first unfiltered, then filtered by the BSS-CCA and pSVD. In both the filtered and unfiltered EEG fragments we estimated multiple dipoles using RAP-MUSIC. The resulting dipoles were subjected to a K-means clustering algorithm, to extract the most prominent cluster. We found that the removal of muscle and eye artifact results to tighter and more clear dipole clusters. Furthermore, we found that localization of the filtered EEG corresponded with the localization derived from the ictal SPECT in 7 of the 8 patients. Therefore, we can conclude that the BSS-CCA and pSVD improve localization of ictal activity, thus making the localization more reliable for the presurgical evaluation of the patient. PMID:17945615

  9. Seasonal Sources of Carbon Exports in a Headwater Stream

    NASA Astrophysics Data System (ADS)

    Argerich, A.; Johnson, S. L.

    2013-12-01

    Climate change is intimately tied to changes in carbon (C) budgets. Understanding the compartments and processes involved in the global C cycle across a landscape is essential to predict future climate change scenarios. While most C budgets focus on terrestrial contributions, river systems contribute to the C cycle by the export of total organic carbon (TOC) and dissolved inorganic carbon (DIC) to the ocean and by exporting CO2 to the atmosphere. Although headwater streams constitute between 60 and 80 percent of fluvial systems their role in the C cycle has often been neglected due to the methodological constrains derived from their heterogeneous morphology. Here we present an analysis of the temporal variation of C export both downstream and evaded to the atmosphere for a headwater stream draining a forested watershed. We relate it to in-stream metabolic processes (respiration and primary production) and to different carbon pools. Specifically, we estimate downstream exports of C in the form of dissolved organic (DOC), dissolved inorganic (DIC), and particulate organic (POC); we estimate the C content in the fine benthic organic matter (FBOM), dead wood, algae, and macroinvertebrate pools; and finally, the amount of CO2 originated and fixed by stream respiration and primary production. Organic exports, both particulate and dissolved, represented 39.7% of the annual downstream export of C while dissolved inorganic C represented 60.3%. Higher exports were observed during periods of high flow (late fall and winter). Highest seasonality in downstream exports was observed for POC (89.5% coefficient of variation in mean monthly fluxes), followed by DOC and DIC (24.3% and 15.9% respectively). Dissolved CO2 had mostly an autochthonous origin during summer (i.e. from stream ecosystem respiration) and originated from allochthonous sources during the rain-dominated months in Oregon (late fall and winter). The stream was net heterotrophic and the amount of C cycled through

  10. Super-fine powdered activated carbon (SPAC) for efficient removal of micropollutants from wastewater treatment plant effluent.

    PubMed

    Bonvin, Florence; Jost, Livia; Randin, Lea; Bonvin, Emmanuel; Kohn, Tamar

    2016-03-01

    In an effort to mitigate the discharge of micropollutants to surface waters, adsorption of micropollutants onto powdered activated carbon (PAC) after conventional wastewater treatment has been identified as a promising technology for enhanced removal of pharmaceuticals and pesticides from wastewater. We investigated the effectiveness of super-fine powdered activated carbon, SPAC, (ca. 1 μm mean particle diameter) in comparison to regular-sized PAC (17-37 μm mean diameter) for the optimization of micropollutant removal from wastewater. Adsorption isotherms and batch kinetic experiments were performed for 10 representative micropollutants (bezafibrate, benzotriazole, carbamazepine, diclofenac, gabapentin, mecoprop, metoprolol, ofloxacin, sulfamethoxazole and trimethoprim) onto three commercial PACs and their super-fine variants in carbonate buffer and in wastewater effluent. SPAC showed substantially faster adsorption kinetics of all micropollutants than conventional PAC, regardless of the micropollutant adsorption affinity and the solution matrix. The total adsorptive capacities of SPAC were similar to those of PAC for two of the three tested carbon materials, in all tested waters. However, in effluent wastewater, the presence of effluent organic matter adversely affected micropollutant removal, resulting in lower removal efficiencies especially for micropollutants with low affinity for adsorbent particles in comparison to pure water. In comparison to PAC, SPAC application resulted in up to two-fold enhanced dissolved organic carbon (DOC) removal from effluent wastewater. The more efficient adsorption process using SPAC translates into a reduction of contact time and contact tank size as well as reduced carbon dosing for a targeted micropollutant removal. In the tested effluent wastewater (5 mg/L DOC), the necessary dose to achieve 80% average removal of indicator micropollutants (benzotriazole, diclofenac, carbamazepine, mecoprop and sulfamethoxazole) ranged

  11. Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge.

    PubMed

    Vanraes, Patrick; Willems, Gert; Nikiforov, Anton; Surmont, Pieter; Lynen, Frederic; Vandamme, Jeroen; Van Durme, Jim; Verheust, Yannick P; Van Hulle, Stijn W H; Dumoulin, Ann; Leys, Christophe

    2015-12-15

    Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC-MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment. PMID:26282086

  12. Removal of molybdate from water by adsorption onto ZnCl2 activated coir pith carbon.

    PubMed

    Namasivayam, C; Sangeetha, D

    2006-07-01

    Removal and recovery of molybdate from aqueous solution was investigated using ZnCl2 activated carbon developed from coir pith. Studies were conducted to delineate the effects of contact time, adsorbent dose, molybdate concentration, pH and temperature. Two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q0) was found to be 18.9 mg molybdate/g of the adsorbent. Adsorption followed second order kinetics. Studies were performed at different pH values to find out the pH at which maximum adsorption occurred. The pH effect and desorption studies showed that ion exchange and chemisorption mechanism were involved in the adsorption process. Thermodynamic parameters such as DeltaG0, DeltaH0 and DeltaS0 for the adsorption were evaluated. Effect of foreign ions on adsorption of molybdate has been examined. The results showed that ZnCl2 activated coir pith carbon was effective for the removal and recovery of molybdate from water. PMID:16006123

  13. Removal of Trace Arsenic to Meet Drinking Water Standards Using Iron Oxide Coated Multiwall Carbon Nanotubes

    PubMed Central

    Ntim, Susana Addo; Mitra, Somenath

    2011-01-01

    This study presents the removal of trace level arsenic to meet drinking water standards using an iron oxide-multi-walled carbon nanotube (Fe-MWCNT) hybrid as a sorbent. The synthesis was facilitated by the high degree of nanotube functionalization using a microwave assisted process, and a controlled assembly of iron oxide was possible where the MWCNT served as an effective support for the oxide. In the final product, 11 % of the carbon atoms were attached to Fe. The Fe-MWCNT was effective in arsenic removal to below the drinking water standard levels of 10 µg L−1. The absorption capacity of the composite was 1723 µg g−1 and 189 µg g−1 for As(III) and As(V) respectively. The adsorption of As(V) on Fe-MWCNT was faster than that of As(III). The pseudo-second order rate equation was found to effectively describe the kinetics of arsenic adsorption. The adsorption isotherms for As(III) and As(V) fitted both the Langmuir and Freundlich models. PMID:21625394

  14. Removing PAHs from urban runoff water by combining ozonation and carbon nano-onions.

    PubMed

    Sakulthaew, Chainarong; Comfort, Steve D; Chokejaroenrat, Chanat; Li, Xu; Harris, Clifford E

    2015-12-01

    Ozone (O3) is a chemical oxidant capable of transforming polycyclic aromatic hydrocarbons (PAHs) in urban runoff within minutes but complete oxidation to CO2 can take days to weeks. We developed and tested a flow-through system that used ozone to quickly transform PAHs in a runoff stream and then removed the ozone-transformed PAHs via adsorption to carbon nano-onions (CNOs). To quantify the efficacy of this approach, (14)C-labeled phenanthrene and benzo(a)pyrene, as well as a mixture of 16 unlabeled PAHs were used as test compounds. These PAHs were pumped from a reservoir into a flow-through reactor that continuously ozonated the solution. Outflow from the reactor then went to a chamber that contained CNOs to adsorb the ozone-transformed PAHs and allowed clean water to pass. By adding a microbial consortium to the CNOs following adsorption, we observed that bacteria were able to degrade the adsorbed products and release more soluble, biodegradable products back into solution. Control treatments confirmed that parent PAH structures (i.e., non-ozonated) were not biologically degraded following CNO adsorption and that O3-transformed PAHs were not released from the CNOs in the absence of bacteria. These results support the combined use of ozone, carbon nano-onions with subsequent biological degradation as a means of removing PAHs from urban runoff or a commercial waste stream. PMID:26291912

  15. Simulation of mercury capture by activated carbon injection in incinerator flue gas. 2. Fabric filter removal.

    PubMed

    Scala, F

    2001-11-01

    Following a companion paper focused on the in-duct mercury capture in incinerator flue gas by powdered activated carbon injection, this paper is concerned with the additional mercury capture on the fabric filter cake, relevant to baghouse equipped facilities. A detailed model is presented for this process, based on material balances on mercury in both gaseous and adsorbed phases along the growing filter cake and inside the activated carbon particles,taking into account mass transfer resistances and adsorption kinetics. Several sorbents of practical interest have been considered, whose parameters have been evaluated from available literature data. The values and range of the operating variables have been chosen in order to simulate typical incinerators operating conditions. Results of simulations indicate that, contrary to the in-duct removal process, high mercury removal efficiencies can be obtained with moderate sorbent consumption, as a consequence of the effective gas/sorbent contacting on the filter. Satisfactory utilization of the sorbents is predicted, especially at long filtration times. The sorbent feed rate can be minimized by using a reactive sorbent and by lowering the filter temperature as much as possible. Minor benefits can be obtained also by decreasing the sorbent particle size and by increasing the cleaning cycle time of the baghouse compartments. Reverse-flow baghouses were more efficient than pulse-jet baghouses, while smoother operation can be obtained by increasing the number of baghouse compartments. Model results are compared with available relevant full scale data. PMID:11718360

  16. Metal oxide absorbents for regenerative carbon dioxide and water vapor removal for advanced portable life support systems

    NASA Technical Reports Server (NTRS)

    Hart, Joan M.; Borghese, Joseph B.; Chang, Craig H.; Stonesifer, Greg T.

    1991-01-01

    Recent studies of Allied Signal metal oxide based absorbents demonstrated that these absorbents offer a unique capability to regeneratively remove both metabolic carbon dioxide and water vapor from breathing air; previously, metal oxides were considered only for the removal of CO2. The concurrent removal of CO2 and H2O vapor can simplify the astronaut Portable Life Support System (PLSS) by combining the CO2 and humidity control functions into one regenerative component. The use of metal oxide absorbents for removal of both CO2 ad H2O vapor in the PLSS is the focus of an ongoing program. The full scale Metal Oxide Carbon dioxide and Humidity Remover (MOCHR) and regeneration unit is described.

  17. Study the properties of activated carbon and oxyhydroxide aluminum as sorbents for removal humic substances from natural waters

    NASA Astrophysics Data System (ADS)

    Shiyan, L. N.; Machekhina, K. I.; Gryaznova, E. N.

    2016-02-01

    The present work relates to the problem of high-quality drinking water supply using processes of adsorption on activated carbon and aluminum oxyhydroxide for removal humic- type organic substances. Also the paper reports on sorbtion properties of the activeted carbon Norit SA UF and oxyhydroxide aluminum for removal humic substances. It was found out that the maximum adsorption capacity of activated carbon to organic substances is equal to 0.25 mg/mg and aluminum oxyhydroxide is equal to 0.3 mg/mg. It is shown that the maximum adsorption capacity of activated carbon Norit SA UF to iron (III) ions is equal to 0.0045 mg/mg and to silicon ions is equal to 0.024 mg/mg. Consequently, the aluminum oxyhydroxide has better adsorption characteristics in comparison with the activated carbon for removal of humic substances, iron and silicon ions. It is associated with the fact that activated carbon has a large adsorption surface, and this is due to its porous structure, but not all molecules can enter into these pores. Therefore, the fibrous structure of aluminum oxyhydroxide promotes better sorption capacity. The presented results suggest that activated carbon Norit SA UF and aluminum oxyhydroxide can be used as sorbents for removal humic substances or other organic substances from groundwater and natural waters.

  18. Hydrocarbon generation and expulsion in shale Vs. carbonate source rocks

    SciTech Connect

    Leythaeuser, D. ); Krooss, B.; Hillebrand, T.; Primio, R. di )

    1993-09-01

    For a number of commercially important source rocks of shale and of carbonate lithologies, which were studied by geochemical, microscopical, and petrophysical techniques, a systematic comparison was made of the processes on how hydrocarbon generation and migration proceed with maturity progress. In this way, several fundamental differences between both types of source rocks were recognized, which are related to differences of sedimentary facies and, more importantly, of diagenetic processes responsible for lithification. Whereas siliciclastic sediments lithify mainly by mechanical compaction, carbonate muds get converted into lithified rocks predominantly by chemical diagenesis. With respect to their role as hydrocarbon source rocks, pressure solution processes appear to be key elements. During modest burial stages and prior to the onset of hydrocarbon generation reactions by thermal decomposition of kerogen, pressure solution seams and stylolites. These offer favorable conditions for hydrocarbon generation and expulsion-a three-dimensional kerogen network and high organic-matter concentrations that lead to effective saturation of the internal pore fluid system once hydrocarbon generation has started. As a consequence, within such zones pore fluids get overpressured, leading ultimately to fracturing. Petroleum expulsion can then occur at high efficiencies and in an explosive fashion, whereby clay minerals and residual kerogen particles are squeezed in a toothpaste-like fashion into newly created fractures. In order to elucidate several of the above outlined steps of hydrocarbon generation and migration processes, open-system hydrous pyrolysis experiments were performed. This approach permits one to monitor changes in yield and composition of hydrocarbon products generated and expelled at 10[degrees]C temperature increments over temperature range, which mimics in the laboratory the conditions prevailing in nature over the entire liquid window interval.

  19. Activated carbon doped with biogenic manganese oxides for the removal of indigo carmine.

    PubMed

    Hu, Yichen; Chen, Xiao; Liu, Zhiqiang; Wang, Gejiao; Liao, Shuijiao

    2016-01-15

    Indigo carmine (IC) is one of the oldest, most important, and highly toxic dyes which is released from the effluents of many industries and results in serious pollution in water. In this study, the biogenic Mn oxides were activated by NaOH and then heated for 3 h at 350 °C to produce activated carbon doped with Mn oxide (Bio-MnOx-C), which were produced by culturing Mn (II)-oxidizing bacterial strain MnI7-9 in liquid A medium at 28 °C with 10 mmol/L MnCl2. Bio-MnOx-C was characterized by SEM, TEM, IR, XPS, XRD, etc. It contained C, O, and Mn which comprised Mn (IV) and Mn (III) valence states at a ratio of 3.81:1. It had poorly crystalline ε-MnO2 with a specific surface area of 130.94 m(2)/g. A total of 0.1 g Bio-MnOx-C could remove 45.95 g IC from 500 mg/L IC solution after 0.5 h contact time. IC removal by Bio-MnOx-C included a rapid oxidation reaction and the removal reaction followed second-order kinetic equation. These results confirmed that Bio-MnOx-C could be a potential material for wastewater remediation. PMID:26595178

  20. Integrating powdered activated carbon into wastewater tertiary filter for micro-pollutant removal.

    PubMed

    Hu, Jingyi; Aarts, Annelies; Shang, Ran; Heijman, Bas; Rietveld, Luuk

    2016-07-15

    Integrating powdered activated carbon (PAC) into wastewater tertiary treatment is a promising technology to reduce organic micro-pollutant (OMP) discharge into the receiving waters. To take advantage of the existing tertiary filter, PAC was pre-embedded inside the filter bed acting as a fixed-bed adsorber. The pre-embedding (i.e. immobilization) of PAC was realized by direct dosing a PAC solution on the filter top, which was then promoted to penetrate into the filter media by a down-flow of tap water. In order to examine the effectiveness of this PAC pre-embedded filter towards OMP removal, batch adsorption tests, representing PAC contact reactor (with the same PAC mass-to-treated water volume ratio as in the PAC pre-embedded filter) were performed as references. Moreover, as a conventional dosing option, PAC was dosed continuously with the filter influent (i.e. the wastewater secondary effluent with the investigated OMPs). Comparative results confirmed a higher OMP removal efficiency associated with the PAC pre-embedded filter, as compared to the batch system with a practical PAC residence time. Furthermore, over a filtration period of 10 h (approximating a realistic filtration cycle for tertiary filters), the continuous dosing approach resulted in less OMP removal. Therefore, it was concluded that the pre-embedding approach can be preferentially considered when integrating PAC into the wastewater tertiary treatment for OMP elimination. PMID:27082256

  1. How to dose powdered activated carbon in deep bed filtration for efficient micropollutant removal.

    PubMed

    Altmann, Johannes; Ruhl, Aki S; Sauter, Daniel; Pohl, Julia; Jekel, Martin

    2015-07-01

    Direct addition of powdered activated carbon (PAC) to the inlet of a deep bed filter represents an energy- and space-saving option to remove organic micropollutants (OMPs) during advanced wastewater treatment or drinking water purification. In this lab-scale study, continuous dosing, preconditioning a filter with PAC and combinations thereof were investigated as possible dosing modes with respect to OMP adsorption efficiency. Continuous dosing resulted in decreasing effluent concentrations with increasing filter runtime due to adsorption onto accumulating PAC in the filter bed. Approximately constant removal levels were achieved at longer filter runtimes, which were mainly determined by the dose of fresh PAC, rather than the total PAC amount embedded. The highest effluent concentrations were observed during the initial filtration stage. Meanwhile, preconditioning led to complete OMP adsorption at the beginning of filtration and subsequent gradual OMP breakthrough. PAC distribution in the pumice filter was determined by the loss on ignition of PAC and pumice and was shown to be relevant for adsorption efficiency. Preconditioning with turbulent upflow led to a homogenous PAC distribution and improved OMP adsorption significantly. Combining partial preconditioning and continuous dosing led to low initial effluent concentrations, but ultimately achieved concentrations similar to filter runs without preconditioning. Furthermore, a dosing stop prior to the end of filtration was suitable to increase PAC efficiency without affecting overall OMP removals. PMID:25898248

  2. Thermal removal of mercury in spent powdered activated carbon from TOXECON process

    SciTech Connect

    Okwadha, G.D.O.; Li, J.; Ramme, B.; Kollakowsky, D.; Michaud, D.

    2009-10-15

    This research developed and demonstrated a technology to liberate Hg adsorbed onto powdered activated carbon (PAC) by the TOXECON process using pilot-scale high temperature air slide (HTAS) and bench-scale thermogravimetric analyzer (TGA). The HTAS removed 65, 83, and 92% of Hg captured with PAC when ran at 900{sup o}F, 1,000{sup o}F, and 1,200 {sup o}F, respectively, while the TGA removed 46 and 100% of Hg at 800 {sup o}F and 900{sup o}F, respectively. However, addition of CuO-Fe{sub 2}O{sub 3} mixture and CuCl catalysts enhanced Hg removal and PAC regeneration at lower temperatures. CuO-Fe{sub 2}O{sub 3} mixture performed better than CuCl in PAC regeneration. Scanning electron microscopy images and energy dispersive X-ray analysis show no change in PAC particle aggregation or chemical composition. Thermally treated sorbents had higher surface area and pore volume than the untreated samples indicating regeneration. The optimum temperature for PAC regeneration in the HTAS was 1,000{sup o}F. At this temperature, the regenerated sorbent had sufficient adsorption capacity similar to its virgin counterpart at 33.9% loss on ignition. Consequently, the regenerated PAC may be recycled back into the system by blending it with virgin PAC.

  3. Simultaneous carbon and nutrient removal in an airlift loop reactor under a limited filamentous bulking state.

    PubMed

    Jiang, Ming; Zhang, Yalei; Zhou, Xuefei; Su, Yimin; Zhang, Min; Zhang, Ke

    2013-02-01

    Airlift loop reactors (ALRs) are important bioreactors for wastewater treatment. However, few studies have investigated the application of an ALR for simultaneous carbon and nutrient removal, especially for activated sludge systems. This study evaluated the performance of integrated nitrogen, phosphorus and COD removal in an ALR with a low height-to-diameter ratio in a limited filamentous bulking (LFB) state (SVI of 180-220mL/g). The average removal efficiencies for COD, NH(4)(+)-N, TN and TP were 91%, 92%, 86% and 94%, respectively. Additional research showed that only under the LFB state, the appropriate distribution of dissolved oxygen inside the ALR was established to promote a well-balanced aerobic and anoxic/anaerobic state. In addition, the macro-gradient of the substrate concentration at the inlet and the heavier bio-P sludge density compensated for the proliferation of filaments. Hence, the stable LFB state was achieved by balancing the floc-forming bacteria and the filamentous bacteria in the ALR. PMID:23313686

  4. Bacterial attachment and removal properties of silicon- and nitrogen-doped diamond-like carbon coatings.

    PubMed

    Zhao, Qi; Su, Xueju; Wang, Su; Zhang, Xiaoling; Navabpour, Parnia; Teer, Dennis

    2009-01-01

    Si- and N-doped diamond-like carbon (DLC) coatings with various Si and N contents were deposited on glass slides using magnetron sputter ion-plating and plasma-enhanced chemical vapour deposition. Surface energy analysis of the DLC coatings revealed that with increasing Si content, the electron acceptor gamma(s)(+) value decreased while the electron donor gamma(s)(-) value increased. The antifouling property of DLC coatings was evaluated with the bacterium, Pseudomonas fluorescens, which is one of the most common microorganisms forming biofilms on the surface of heat exchangers in cooling water systems. P. fluorescens had a high value of the gamma(s)(-) component (69.78 mN m(-1)) and a low value of the gamma(s)(+) component (5.97 mN m(-1)), and would be negatively charged with the zeta potential of -16.1 mV. The experimental results showed that bacterial removal by a standardised washing procedure increased significantly with increasing electron donor gamma(s)(-) values and with decreasing electron acceptor gamma(s)(+) values of DLC coatings. The incorporation of 2%N into the Si-doped DLC coatings further significantly reduced bacterial attachment and significantly increased ease of removal. The best Si-N-doped DLC coatings reduced bacterial attachment by 58% and increased removal by 41%, compared with a silicone coating, Silastic T2. Bacterial adhesion strength on the DLC coatings is explained in terms of thermodynamic work of adhesion. PMID:19283517

  5. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Saarikoski, S.; Tolonen-Kivimäki, O.; Aurela, M.; Saarnio, K.; Petäjä, T.; Aalto, P. P.; Kulmala, M.; Pakkanen, T.; Hillamo, R.

    2008-04-01

    This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC), inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III) by using a micro-orifice uniform deposit impactor (MOUDI). The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC) and monosaccharide anhydrides from the filter samples. During the measurements gravimetric mass in the MOUDI collections varied between 3.4 and 55.0 μg m-3 and the WSOC concentration was between 0.3 and 7.4 μg m-3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6) comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1-10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1-10 aerosol mass. Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas). Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs) and aerosols as well as various transformation processes are likely to have an impact on the measured aerosol composition. Using the source categories, it was identified that especially the oxidation products of biogenic VOCs in summer had a clear effect on WSOC concentrations.

  6. Comparing carbon sequestration potential of pyrogenic carbon from natural and anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Santin, Cristina; Doerr, Stefan; Merino, Augustin

    2014-05-01

    The enhanced resistance to environmental degradation of Pyrogenic Carbon (PyC), both produced in wildfires (charcoal), and man-made (biochar), gives it the potential to sequester carbon by preventing it to be released into the atmosphere. Sustainable addition of biochar to soils is seen as a viable global approach for carbon sequestration and climate change mitigation. Also the role of its 'natural counterpart', i.e. wildfire charcoal, as a long-term carbon sink in soils is widely recognized. However, in spite of their fundamental similarities, research on the potential of 'man-made' biochar and wildfire charcoal for carbon sequestration has been carried out essentially in isolation as analogous materials for accurate comparison are not easily available. Here we assess the carbon sequestration potential of man-made biochar and wildfire charcoal generated from the same material under known production conditions: (i) charcoal from forest floor and down wood produced during an experimental boreal forest fire (FireSmart, June 2012, NWT- Canada) and (ii) biochar produced from the same feedstock by slow pyrolysis [three treatments: 2 h at 350, 500 and 650°C, respectively]. The carbon sequestration potential of these PyC materials is given by the recalcitrance index, R50, proposed by Harvey et al. (2012). R50 is based on the relative thermal stability of a given PyC material to that of graphite and is calculated using thermogravimetric analyses. Our results show highest R50 for PyC materials produced from down wood than from forest floor, which points to the importance of feedstock chemical composition in determining the C sequestration potential of PyC both from natural (charcoal) and anthropogenic (biochar) sources. Moreover, production temperature is also a major factor affecting the carbon sequestration potential of the studied PyC materials, with higher R50 for PyC produced at higher temperatures. Further investigation on the similarities and differences between man

  7. Simultaneous removal of multiple odorants from source water suffering from septic and musty odors: Verification in a full-scale water treatment plant with ozonation.

    PubMed

    Guo, Qingyuan; Yang, Kai; Yu, Jianwei; Wang, Chunmiao; Wen, Xiaodong; Zhang, Liping; Yang, Min; Xia, Ping; Zhang, Dong

    2016-09-01

    Ozonation is known to be very effective in the removal of odorants from source water. However, it is not known if ozonation is effective in the removal of multiple odorants causing different types of odors. In this study, the removal performance for odors and odorants were evaluated in a Water Treatment Plant (WTP), which was equipped with coagulation, sedimentation, ozonation, biological activated carbon (BAC) filtration, sand filtration, and chlorination in succession and located in the downstream of the Huangpu (HP) River, over the period from April, 2014 to April, 2015. Flavor profile analysis (FPA) results showed that the source water was constantly associated with septic and musty odors. Geosmin and 2-MIB, with an average OAV of 4.54 and 1.38, respectively, were the major odorants for musty odor, while bis(2-chloroisopropyl) ether, DEDS and DMDS with an average OAV of 2.35, 1.65 and 0.78, respectively, might be responsible for the septic odor. While the musty odor could be removed effectively through the combination of ozonation and BAC, the septic odor and associated odorants required further treatment with sand filtration and chlorination for complete removal. It is clear that the advanced treatment process was effective for the treatment of source water containing complicated odorants. It should be noted that the sedimentation process needs careful management because release of odorants may occur during the treatment. The result of this study will be helpful for the mitigation of odors in WTP using source waters suffering from complicated odor problems. PMID:27173729

  8. Importance of seagrass as a carbon source for heterotrophic bacteria in a subtropical estuary (Florida Bay)

    NASA Astrophysics Data System (ADS)

    Williams, Clayton J.; Jaffé, Rudolf; Anderson, William T.; Jochem, Frank J.

    2009-11-01

    A stable carbon isotope approach was taken to identify potential organic matter sources incorporated into biomass by the heterotrophic bacterial community of Florida Bay, a subtropical estuary with a recent history of seagrass loss and phytoplankton blooms. To gain a more complete understanding of bacterial carbon cycling in seagrass estuaries, this study focused on the importance of seagrass-derived organic matter to pelagic, seagrass epiphytic, and sediment surface bacteria. Particulate organic matter (POM), seagrass epiphytic, seagrass ( Thalassia testudinum) leaf, and sediment surface samples were collected from four Florida Bay locations with historically different organic matter inputs, macrophyte densities, and primary productivities. Bulk (observed and those reported previously) and compound-specific bacterial fatty acid δ 13C values were used to determine important carbon sources to the estuary and benthic and pelagic heterotrophic bacteria. The δ 13C values of T. testudinum green leaves with epiphytes removed ranged from -9.9 to -6.9‰. Thalassia testudinum δ 13C values were significant more enriched in 13C than POM, epiphytic, and sediment samples, which ranged from -16.4 to -13.5, -16.2 to -9.6, and -16.7 to -11.0‰, respectively. Bacterial fatty acid δ 13C values (measured for br14:0, 15:0, i15:0, a15:0, br17:0, and 17:0) ranged from -25.5 to -8.2‰. Assuming a -3‰ carbon source fractionation from fatty acid to whole bacteria, pelagic, epiphytic, and sediment bacterial δ 13C values were generally more depleted in 13C than T. testudinum δ 13C values, more enriched in 13C than reported δ 13C values for mangroves, and similar to reported δ 13C values for algae. IsoSource mixing model results indicated that organic matter derived from T. testudinum was incorporated by both benthic and pelagic bacterial communities, where 13-67% of bacterial δ 13C values could arise from consumption of seagrass-derived organic matter. The IsoSource model

  9. Selective removal of nitrate ion using a novel composite carbon electrode in capacitive deionization.

    PubMed

    Kim, Yu-Jin; Choi, Jae-Hwan

    2012-11-15

    We fabricated nitrate-selective composite carbon electrodes (NSCCEs) for use in capacitive deionization to remove nitrate ions selectively from a solution containing a mixture of anions. The NSCCE was fabricated by coating the surface of a carbon electrode with the anion exchange resin, BHP55, after grinding the resin into fine powder. BHP55 is known to be selective for nitrate ions. We performed desalination experiments on a solution containing 5.0 mM NaCl and 2.0 mM NaNO(3) using the NSCCE system constructed with the fabricated electrode. The selective removal of nitrate in the NSCCE system was compared to a membrane capacitive deionization (MCDI) system constructed with ion exchange membranes and carbon electrodes. The total quantity of chloride and nitrate ions adsorbed onto the unit area of the electrode in the MCDI system was 25 mmol/m(2) at a cell potential of 1.0 V. The adsorption of nitrate ions was 8.3 mmol/m(2), accounting for 33% of the total. In contrast, the total anion adsorption in the NSCCE system was 34 mmol/m(2), 36% greater than the total anion adsorption of the MCDI system. The adsorption of nitrate ions was 19 mmol/m(2), 2.3-times greater than the adsorption in the MCDI system. These results showed that the ions were initially adsorbed by an electrostatic force, and the ion exchange reactions then occurred between the resin powder in the coated layer and the solution containing mixed anions. PMID:22980574

  10. Combination of powdered activated carbon and powdered zeolite for enhancing ammonium removal in micro-polluted raw water.

    PubMed

    Liao, Zhen-Liang; Chen, Hao; Zhu, Bai-Rong; Li, Huai-Zheng

    2015-09-01

    Even zeolite is promising in ammonia pollution disposing, its removal efficiency is frequently interfered by organics. As activated carbon has good removal efficiency on organic contaminants, combination of two adsorbents may allow their respective adsorption characteristics into full play. This paper provides a performance assessment of the combination for enhancing ammonium removal in micro-polluted raw water. Gel-filtration chromatography (GFC) was carried out to quantify the molecular weight (MW) range of organic contaminants that powdered activated carbon (PAC) and powdered zeolite (PZ) can remove. The polydispersity difference which also calculated from GFC may indicate the wider organic contaminants removal range of PAC and the relatively centralized removal range of PZ. The jar tests of combination dosing confirm a synergistic effect which promotes ammonium removing. Nevertheless, it also shows an antagonism hindering the due removal performance of the two adsorbents on CODMn, while it is not much evident on UV254. Furthermore, a comparison study with simulated coagulation-sedimentation process was conducted to evaluate the optimum dosing points (spatial and temporal) of PAC and PZ among follows: suction well, pipeline mixer, early and middle phase of flocculation. We suggest to dose both two adsorbents into the early phase of flocculation to maximize the versatile removal efficiency on turbidity, ammonium and organic contaminants. PMID:25929873

  11. Organic Carbon Sources in Coastal Southeast Alaskan Streams

    NASA Astrophysics Data System (ADS)

    Hood, E.; Edwards, R. T.; D'Amore, D. V.; Lange, B. J.

    2003-12-01

    Dissolved organic matter (DOM) is abundant in southeast Alaskan watersheds and plays an important role in the biological and physical processes in these aquatic systems. Nearly 30% of the land area in southeast Alaska is classified as wetlands, a large proportion of which are peatlands. Peatlands are thought to provide substantial DOM to surface waters. Another important source of carbon to streams is spawning anadromous salmon. This study examines how streamwater concentrations of DOC are influenced by 1) catchments soils and vegetation, particularly wetland extent and 2) the presence or absence of anadromous fish. Our goal is to characterize the quantity and quality of different DOM sources and to develop an understanding of how these sources influence seasonal trends in streamwater DOM in coastal freshwater systems in southeast Alaska. Surface water and well samples were collected on two contrasting streams near Juneau, Alaska: Peterson Creek, a brownwater, high-carbon stream in a wetland-dominated catchment and McGinnis Creek, a clearwater stream draining upland spruce forest and alpine tundra. Both streams have runs of pink, coho, and chum salmon from July-September. Streamwater DOC concentrations on Peterson Creek averaged 5-6 mg C L-1 during the early summer and increased to 8-12 mg C L-1 during late July and August. Streamwater DOC concentrations on McGinnis Creek were typically less than 1 mg C L-1 during the early summer but increased dramatically to 4-9 mg C L-1 during spates in August. Well samples collected upslope from the streamwater sampling sites on Peterson and McGinnis Creeks had a similar range in DOC concentrations (10-40 mg C L-1), however the wells on McGinnis Creek showed much higher seasonal variability. Our initial results suggest that the seasonal increase in DOC in both streams is primarily associated with the flushing of soluble organic carbon from catchment soils by late summer rains. However, leaching of DOC from salmon carcasses may

  12. Carbon Dioxide Capture and Separation Techniques for Gasification-based Power Generation Point Sources

    SciTech Connect

    Pennline, H.W.; Luebke, D.R.; Jones, K.L.; Morsi, B.I.; Heintz, Y.J.; Ilconich, J.B.

    2007-06-01

    The capture/separation step for carbon dioxide (CO2) from large-point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large-point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the in-house research area of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the research has focused on capture/separation of carbon dioxide from flue gas (post-combustion from fossil fuel-fired combustors) and from fuel gas (precombustion, such as integrated gasification combined cycle or IGCC). With respect to fuel gas applications, novel concepts are being developed in wet scrubbing with physical absorption; chemical absorption with solid sorbents; and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an ideal solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO2-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, dry, regenerable processes based on sorbents are additional techniques for CO2 capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.

  13. Carbon dioxide capture and separation techniques for advanced power generation point sources

    SciTech Connect

    Pennline, H.W.; Luebke, D.R.; Morsi, B.I.; Heintz, Y.J.; Jones, K.L.; Ilconich, J.B.

    2006-09-01

    The capture/separation step for carbon dioxide (CO2) from large-point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large-point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the in-house research area of the National Energy Technology Laboratory possess the potential for improved efficiency and costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the research has focused on capture/separation of carbon dioxide from flue gas (postcombustion from fossil fuel-fired combustors) and from fuel gas (precombustion, such as integrated gasification combined cycle – IGCC). With respect to fuel gas applications, novel concepts are being developed in wet scrubbing with physical absorption; chemical absorption with solid sorbents; and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an ideal solvent has led to the study of the solubility and mass transfer properties of various solvents. Fabrication techniques and mechanistic studies for hybrid membranes separating CO2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO2-philic silanes incorporated into an alumina support or ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. An overview of two novel techniques is presented along with a research progress status of each technology.

  14. Removal of chromium(VI) from wastewater using phosphoric acid treated activated carbon

    NASA Astrophysics Data System (ADS)

    Suganthi, N.

    2013-06-01

    Activated carbon prepared by phosphoric acid treatment of tamarind nuts (seeds) was investigated for the removal of Cr(VI) from aqueous solutions. The characteristics of phosphorylated tamarind nut carbon (PTNC) were evaluated for porosity and surface area. The effect of contact time, pH, adsorbent dose and particle size variation were studied to evaluate the potential applicability of carbon for treating Cr(VI) containing wastewater. The adsorbent data were modeled by Langmiur and Freundlich classical adsorption isotherms. The kinetic studies showed that Cr(VI) adsorption on PTNC was in compliance with the pseudo-second-order kinetic model. Desorption studies indicated that ion-exchange mechanism was operating. The continuous adsorption was studied in glass columns of 2.5 cm diameter using electroplating wastewater to ascertain the practical applicability of PTNC in large scale. The mechanism of adsorption was found to be ion-exchange process and was supported by FTIR spectroscopy. The surface modification after adsorption was confirmed by SEM studies.

  15. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    PubMed

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems. PMID:27054722

  16. A Novel Airborne Carbon Isotope Analyzer for Methane and Carbon Dioxide Source Fingerprinting

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Huang, Y. W.; Owano, T. G.; Leifer, I.

    2014-12-01

    Recent field studies on major sources of the important greenhouse gas methane (CH4) indicate significant underestimation of methane release from fossil fuel industrial (FFI) and animal husbandry sources, among others. In addition, uncertainties still exist with respect to carbon dioxide (CO2) measurements, especially source fingerprinting. CO2 isotopic analysis provides a valuable in situ measurement approach to fingerprint CH4 and CO2as associated with combustion sources, leakage from geologic reservoirs, or biogenic sources. As a result, these measurements can characterize strong combustion source plumes, such as power plant emissions, and discriminate these emissions from other sources. As part of the COMEX (CO2 and MEthane eXperiment) campaign, a novel CO2 isotopic analyzer was installed and collected data aboard the CIRPAS Twin Otter aircraft. Developing methods to derive CH4 and CO2 budgets from remote sensing data is the goal of the summer 2014 COMEX campaign, which combines hyperspectral imaging (HSI) and non-imaging spectroscopy (NIS) with in situ airborne and surface data. COMEX leverages the synergy between high spatial resolution HSI and moderate spatial resolution NIS. The carbon dioxide isotope analyzer developed by Los Gatos Research (LGR) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures CO2 concentration as well as δ13C, δ18O, and δ17O from CO2 at natural abundance (100-3000 ppm). The laboratory accuracy is ±1.2 ppm (1σ) in CO2 from 370-1000 ppm, with a long-term (1000 s) precision of ±0.012 ppm. The long-term precision for both δ13C and δ18O is 0.04 ‰, and for δ17O is 0.06 ‰. The analyzer was field-tested as part of the COWGAS campaign, a pre-cursor campaign to COMEX in March 2014, where it successfully discriminated plumes related to combustion processes associated with

  17. Ozonation and activated carbon treatment of sewage effluents: removal of endocrine activity and cytotoxicity.

    PubMed

    Stalter, Daniel; Magdeburg, Axel; Wagner, Martin; Oehlmann, Jörg

    2011-01-01

    Concerns about endocrine disrupting compounds in sewage treatment plant (STP) effluents give rise to the implementation of advanced treatment steps for the elimination of trace organic contaminants. The present study investigated the effects of ozonation (O(3)) and activated carbon treatment (AC) on endocrine activities [estrogenicity, anti-estrogenicity, androgenicity, anti-androgenicity, aryl-hydrocarbon receptor (AhR) agonistic activity] with yeast-based bioassays. To evaluate the removal of non-specific toxicity, a cytotoxicity assay using a rat cell line was applied. Wastewater (WW) was sampled at two STPs after conventional activated sludge treatment following the secondary clarifier (SC) and after subsequent advanced treatments: O(3), O(3) + sand filtration (O(3-SF)), and AC. Conventional treatment reduced estrogenicity, androgenicity, and AhR agonistic activity by 78-99% compared to the untreated influent WW. Anti-androgenicity and anti-estrogenicity were not detectable in the influent but appeared in SC, possibly due to the more effective removal of respective agonists during conventional treatment. Endocrine activities after SC ranged from 2.0 to 2.8 ng/L estradiol equivalents (estrogenicity), from 4 to 22 μg/L 4-hydroxytamoxifen equivalents (anti-estrogenicity), from 1.9 to 2.0 ng/L testosterone equivalents (androgenicity), from 302 to 614 μg/L flutamide equivalents (anti-androgenicity), and from 387 to 741 ng/L β-naphthoflavone equivalents (AhR agonistic activity). In particular, estrogenicity and anti-androgenicity occurred in environmentally relevant concentrations. O(3) and AC further reduced endocrine activities effectively (estrogenicity: 77-99%, anti-androgenicity: 63-96%, AhR agonistic activity: 79-82%). The cytotoxicity assay exhibited a 32% removal of non-specific toxicity after O(3) compared to SC. O(3) and sand filtration reduced cytotoxic effects by 49%, indicating that sand filtration contributes to the removal of toxicants. AC was the

  18. Forest Restoration Carbon Analysis of Baseline Carbon Emissions and Removal in Tropical Rainforest at La Selva Central, Peru

    SciTech Connect

    Patrick Gonzalez; Benjamin Kroll; Carlos R. Vargas

    2006-01-10

    Conversion of tropical forest to agricultural land and pasture has reduced forest extent and the provision of ecosystem services, including watershed protection, biodiversity conservation, and carbon sequestration. Forest conservation and reforestation can restore those ecosystem services. We have assessed forest species patterns, quantified deforestation and reforestation rates, and projected future baseline carbon emissions and removal in Amazon tropical rainforest at La Selva Central, Peru. The research area is a 4800 km{sup 2} buffer zone around the Parque Nacional Yanachaga-Chemillen, Bosque de Proteccion San Matias-San Carlos, and the Reserva Comunal Yanesha. A planned project for the period 2006-2035 would conserve 4000 ha of forest in a proposed 7000 ha Area de Conservacion Municipale de Chontabamba and establish 5600 ha of natural regeneration and 1400 ha of native species plantations, laid out in fajas de enriquecimiento (contour plantings), to reforest 7000 ha of agricultural land. Forest inventories of seven sites covering 22.6 ha in primary forest and 17 sites covering 16.5 ha in secondary forest measured 17,073 trees of diameter {ge} 10 cm. The 24 sites host trees of 512 species, 267 genera, and 69 families. We could not identify the family of 7% of the trees or the scientific species of 21% of the trees. Species richness is 346 in primary forest and 257 in the secondary forest. In primary forest, 90% of aboveground biomass resides in old-growth species. Conversely, in secondary forest, 66% of aboveground biomass rests in successional species. The density of trees of diameter {ge} 10 cm is 366 trees ha{sup -1} in primary forest and 533 trees ha{sup -1} in secondary forest, although the average diameter is 24 {+-} 15 cm in primary forest and 17 {+-} 8 cm in secondary forest. Using Amazon forest biomass equations and wood densities for 117 species, aboveground biomass is 240 {+-} 30 t ha{sup -1} in the primary sites and 90 {+-} 10 t ha{sup -1} in the

  19. Grazer traits, competition, and carbon sources to a headwater-stream food web.

    PubMed

    McNeely, Camille; Finlay, Jacques C; Power, Mary E

    2007-02-01

    We investigated the effect of grazing by a dominant invertebrate grazer (the caddisfly Glossosoma penitum) on the energy sources used by other consumers in a headwater-stream food web. Stable isotope studies in small, forested streams in northern California have shown that G. penitum larvae derive most of their carbon from algae, despite low algal standing crops. We hypothesized that the caddisfly competes with other primary consumers (including mayflies) for algal food and increases their reliance on terrestrial detritus. Because Glossosoma are abundant and defended from predators by stone cases, their consumption of algal energy may reduce its transfer up the food chain. We removed Glossosoma (natural densities >1000 caddisflies/m2) from five approximately 4 m2) stream sections during the summer of 2000 and measured responses of algae, invertebrate primary consumers, and invertebrate predators. The treatment reduced Glossosoma biomass by 80-90%. We observed a doubling in chlorophyll a per area in sections with reduced Glossosoma abundance and aggregative increases in the biomass of undefended primary consumers. Heptageniid mayfly larvae consumed more algae (as measured by stable carbon isotope ratios and gut content analysis) in caddisfly removal plots at the end of the 60-day experiment, although not after one month. We did not see isotopic evidence of increased algal carbon in invertebrate predators, however. Patterns of caddisfly and mayfly diets in the surrounding watershed suggested that mayfly diets are variable and include algae and detrital carbon in variable proportions, but scraping caddisflies consume primarily algae. Caddisfly and mayfly diets are more similar in larger, more productive streams where the mayflies assimilate more algae. Isotopic analysis, in combination with measurements of macroinvertebrate abundance and biomass in unmanipulated plots, suggested that a substantial portion of the invertebrate community (>50% of biomass) was supported

  20. Role of SO{sub 2} for elemental mercury removal from coal combustion flue gas by activated carbon

    SciTech Connect

    M. Azhar Uddin; Toru Yamada; Ryota Ochiai; Eiji Sasaoka

    2008-07-15

    In order to clarify the role of SO{sub 2} in the removal of mercury from coal combustion flue gas by activated carbon, the removal of Hg{sup 0} vapor from simulated coal combustion flue gas containing SO{sub 2} by a commercial activated carbon (AC) was studied. The Hg{sup 0} removal experiments were carried out in a conventional flow type packed bed reactor system with simulated flue gases having a composition of Hg{sup 0} (4.9 ppb), SO{sub 2} (0 or 500 ppm), CO{sub 2} (10%), H{sub 2}O (0 or 15%), O{sub 2} (0 or 5%), and N{sub 2} (balance gas) at a space velocity (SV) of 6.0 x 104 h{sup -1} in a temperature rang 60-100 {sup o}C. It was found that, for SO{sub 2} containing flue gas, the presence of both O{sub 2} and H{sub 2}O was necessary for the removal of Hg{sup 0} and the Hg{sup 0} removal was favored by lowering the reaction temperature in the order of 60 > 80 > 100{sup o}C. The presence of SO{sub 2} in the flue was essential for the removal of Hg{sup 0} by untreated activated carbon. The activated carbons pretreated with SO{sub 2} or H{sub 2}SO{sub 4} prior to the Hg{sup 0} removal also showed Hg{sup 0} removal activities even in the absence of SO{sub 2}; however, the presence of SO{sub 2} also suppressed the Hg{sup 0} removal of the SO{sub 2}-pretreated AC or H{sub 2}SO{sub 4} preadded AC. 19 refs., 11 figs.

  1. Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source

    PubMed Central

    Maron, Pierre-Alain; Menasseri-Aubry, Safya; Sarr, Amadou; Lévêque, Jean; Mathieu, Olivier; Jolivet, Claudy; Leterme, Philippe; Viaud, Valérie

    2016-01-01

    Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and

  2. Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

    PubMed

    Louis, Benjamin P; Maron, Pierre-Alain; Menasseri-Aubry, Safya; Sarr, Amadou; Lévêque, Jean; Mathieu, Olivier; Jolivet, Claudy; Leterme, Philippe; Viaud, Valérie

    2016-01-01

    Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and

  3. Addressing sources of uncertainty in a global terrestrial carbon model

    NASA Astrophysics Data System (ADS)

    Exbrayat, J.; Pitman, A. J.; Zhang, Q.; Abramowitz, G.; Wang, Y.

    2013-12-01

    Several sources of uncertainty exist in the parameterization of the land carbon cycle in current Earth System Models (ESMs). For example, recently implemented interactions between the carbon (C), nitrogen (N) and phosphorus (P) cycles lead to diverse changes in land-atmosphere C fluxes simulated by different models. Further, although soil organic matter decomposition is commonly parameterized as a first-order decay process, the formulation of the microbial response to changes in soil moisture and soil temperature varies tremendously between models. Here, we examine the sensitivity of historical land-atmosphere C fluxes simulated by an ESM to these two major sources of uncertainty. We implement three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in the CABLE-CASA-CNP land biogeochemical component of the coarse resolution CSIRO Mk3L climate model. Simulations are undertaken using three degrees of biogeochemical nutrient limitation: C-only, C and N, and C and N and P. We first bring all 27 possible combinations of a SMRF with a STRF and a biogeochemical mode to a steady-state in their biogeochemical pools. Then, transient historical (1850-2005) simulations are driven by prescribed atmospheric CO2 concentrations used in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Similarly to some previously published results, representing N and P limitation on primary production reduces the global land carbon sink while some regions become net C sources over the historical period (1850-2005). However, the uncertainty due to the SMRFs and STRFs does not decrease relative to the inter-annual variability in net uptake when N and P limitations are added. Differences in the SMRFs and STRFs and their effect on the soil C balance can also change the sign of some regional sinks. We show that this response is mostly driven by the pool size achieved at the end of the spin-up procedure. Further, there exists a six-fold range in the level

  4. Waste tires: A future source of activated carbon?

    SciTech Connect

    1996-01-01

    Millions of used tires are disposed in the United States each year, causing major environmental problems and representing a loss of valuable resources. Currently, over 80% of discarded tires are landfilled (approximately 200 million per year). Because tires disposed in municipal landfills rarely stay buried, regulators, landfill operators, and even the general public are constantly reminded of this problem. These ever-surfacing tires can serve as a breeding ground for disease-causing mosquitoes; in addition, large mounds of tires often catch fire, causing significant air pollution. Recent research indicates that used tires may soon represent a source of carbon-based adsorbents and energy-rich liquid and gaseous hydrocarbons. Details of this research are discussed briefly in this paper. 3 refs., 2 figs.

  5. Effect of carbon source on pyrimidine biosynthesis in Pseudomonas oryzihabitans.

    PubMed

    West, Thomas P

    2010-08-01

    The effect of carbon source on the regulation of pyrimidine biosynthesis in the opportunistic human pathogen Pseudomonas oryzihabitans was studied at the level of enzyme synthesis. Although pyrimidine supplementation of glucose-grown Ps. oryzihabitans cells produced a slight but statistically significant effect on the de novo pyrimidine biosynthetic pathway enzyme activities, catabolite repression of the enzyme activities by glucose appeared to be occurring. Pyrimidine limitation experiments undertaken using an orotidine 5'-monophosphate decarboxylase mutant strain grown on glucose indicated that repression of enzyme synthesis by pyrimidines was occurring. Following pyrimidine limitation of the mutant strain cells, dihydroorotase and dihydroorotate dehydrogenase activities were found to about double while aspartate transcarbamoylase and orotate phosphoribosyltransferase activities were slightly elevated compared to their activities in the mutant strain cells grown on excess uracil. PMID:20473969

  6. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Saarikoski, S.; Tolonen-Kivimäki, O.; Aurela, M.; Saarnio, K.; Petäjä, T.; Aalto, P. P.; Kulmala, M.; Pakkanen, T.; Hillamo, R.

    2008-09-01

    This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC), inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III) by using a micro-orifice uniform deposit impactor (MOUDI). The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC) and monosaccharide anhydrides from the filter samples (particle aerodynamic diameter smaller than 1 μm, PM1). Gravimetric mass concentration varied during the MOUDI samplings between 3.4 and 55.0 μg m-3 and the WSOC concentrations were between 0.3 and 7.4 μg m-3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6 to convert the analyzed carbon mass to organic matter mass) comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1-10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1-10 aerosol mass. Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas). Categories were identified mainly using levoglucosan concentration level for wood combustion and air mass backward trajectories for other groups. Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs) and aerosols as well as various transformation processes are likely to have an impact on the measured aerosol composition. Using the source categories, it was identified that

  7. Trends in the sources and sinks of carbon dioxide

    SciTech Connect

    Le Quere, Corrine; Raupach, Mike; Canadell, J.G.; Marland, Gregg; Bopp, Laurent; Ciais, Philippe; Friedlingstein, Pierre; Viovy, Nicolas; Conway, T.J.; Doney, Scott C.; Feely, R. A.; Foster, Pru; House, Joanna I; Prentice, Colin I.; Gurney, Kevin; Houghton, R.A.; Huntingford, Chris; Levy, Peter E.; Lomas, M. R.; Woodward, F. I.; Majkut, Joseph; Sarmiento, Jorge L.; Metzl, Nicolas; Ometto, Jean P; Randerson, James T.; Peters, Glen P; Running, Steven; Sitch, Stephen; Takahashi, Taro; Van der Werf, Guido

    2009-12-01

    Efforts to control climate change require the stabilization of atmospheric CO2 concentrations. This can only be achieved through a drastic reduction of global CO2 emissions. Yet fossil fuel emissions increased by 29% between 2000 and 2008, in conjunction with increased contributions from emerging economies, from the production and international trade of goods and services, and from the use of coal as a fuel source. In contrast, emissions from land-use changes were nearly constant. Between 1959 and 2008, 43% of each year's CO2 emissions remained in the atmosphere on average; the rest was absorbed by carbon sinks on land and in the oceans. In the past 50 years, the fraction of CO2 emissions that remains in the atmosphere each year has likely increased, from about 40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by the carbon sinks in response to climate change and variability. Changes in the CO2 sinks are highly uncertain, but they could have a significant influence on future atmospheric CO2 levels. It is therefore crucial to reduce the uncertainties.

  8. Carbon Nanotube/Magnesium Composite as a Hydrogen Source.

    PubMed

    Yu, Min Kyu; Se, Kwon Oh; Kim, Min Joong; Hwang, Jae Won; Yoon, Byoung Young; Kwon, Hyuk Sang

    2015-11-01

    Hydrogen produced using the steam reforming process contains sulfur and carbon monoxide that are harmful to the Pt catalyst in proton-exchange-membrane fuel cells (PEMFCs). However, CO-free hydrogen can be generated from the hydrolysis of either Al in strongly alkaline water or Mg in neutral water with chlorides such as sea water. The hydrogen generation rate from the hydrolysis of Mg is extremely slow and linearly proportional to the corrosion rate of Mg in chloride water. In this work, we fabricated a carbon nanotube (CNT)--reinforced Mg--matrix composite by Spark Plasma Sintering as a fast hydrogen generation source for a PEMFC. The CNTs distributed in the Mg matrix act as numerous local cathodes, and hence cause severe galvanic corrosion between the Mg-matrix anode and CNT-cathode in NaCl solution. It was found that the hydrogen generation rate from the hydrolysis of the 5 vol.% CNT/Mg composite is 3300 times faster than that of the Mg without CNTs due primarily to the galvanic corrosion effect. PMID:26726603

  9. Do Vermont's Floodplains Constitute an Important Source of Labile Carbon?

    NASA Astrophysics Data System (ADS)

    Perdrial, J. N.; Dolan, A.; Kemsley, M.

    2014-12-01

    Floodplains are extremely heterogeneous landscapes with respect to soil and sediment composition and can present an important source of carbon (C) during floods. For example, stream bank soils and sediments are zones of active erosion and deposition of sediment associated C. Due to the presence of plants, riparian soils contain high amounts of C that is exchanged between stream waters and banks. Abandoned channels and meander wetlands that remain hydrologically connected to the main channel contain high amounts of organic matter that can be flushed into the stream during high discharge. This heterogeneity, result of floodplain geomorphology, land cover and use, can profoundly impact the amount and type of dissolved organic matter (DOM) introduced into streams. In order to assess DOM characteristics leached from heterogeneous floodplain soils, aqueous soil extracts were performed on soil samples representative of different land covers (n=20) at four depths. Extracts were analyzed for dissolved organic C and total dissolved nitrogen with a Shimadzu C analyzer. Colored dissolved organic matter characteristics was measured with the Aqualog Fluorescence Spectrometer and quantified with parallel factor analysis (PARAFAC). Preliminary data from three floodplains in Vermont (Connecticut, Missisquoi and Mad River) show a 3D variability of longitudinal, lateral, and vertical extents on water-extractable, mobile C. Dissolved organic carbon concentrations in meander swamp samples were found up to 9 times higher than in those of soils from agricultural field indicative of an important C source. Although C concentrations in adjacent fields were low, high abundance of labile C (indicated by tryptophan-like fluorescence) in water extracts from fields indicates recent biological production of C. This labile C is easily processed by microbes and transformed to the greenhouse gas CO2. These results provide important information on the contribution and lability of different floodplain

  10. Black carbon from the Mississippi River: quantities, sources, and potential implications for the global carbon cycle.

    PubMed

    Mitra, Siddhartha; Bianchi, Thomas S; McKee, Brent A; Sutula, Martha

    2002-06-01

    Black carbon (BC) may be a major component of riverine carbon exported to the ocean, but its flux from large rivers is unknown. Furthermore, the global distribution of BC between natural and anthropogenic sources remains uncertain. We have determined BC concentrations in suspended sediments of the Mississippi River, the 7th largest river in the world in terms of sediment and water discharge, during high flow and low flow in 1999. The 1999 annual flux of BC from the Mississippi River was 5 x 10(-4) petagrams (1 Pg = 10(15) g = 1 gigaton). We also applied a principal components analysis to particulate-phase high molecular weight polycyclic aromatic hydrocarbon isomer ratios in Mississippi River suspended sediments. In doing so, we determined that approximately 27% of the BC discharged from the Mississippi River in 1999 originated from fossil fuel combustion (coal and smelter-derived combustion), implicating fluvial BC as an important source of anthropogenic BC contamination into the ocean. Using our value for BC flux and the annual estimate for BC burial in ocean sediments, we calculate that, in 1999, the Mississippi River discharged approximately 5% of the BC buried annually in the ocean. These results have important implications, not only for the global carbon cycle but also for the fluvial discharge of particulate organic contaminants into the world's oceans. PMID:12075780

  11. Chemical Characterization and Removal of Carbon-14 from Irradiated Graphite II - 13023

    SciTech Connect

    Dunzik-Gougar, Mary Lou; Cleaver, James; LaBrier, Daniel; McCrory, Shilo; Smith, Tara E.

    2013-07-01

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 (C-14), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates C-14 is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented last year and updated here is to identify the chemical form of C-14 in irradiated graphite and develop a practical method by which C-14 can be removed. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoam{sup R}, were exposed to liquid nitrogen (to increase the quantity of C-14 precursor) and neutron-irradiated (10{sup 13} neutrons/cm{sup 2}/s). Finer grained NBG-25 was not exposed to liquid nitrogen prior to irradiation at a neutron flux on the order of 10{sup 14} /cm{sup 2}/s. Characterization of pre- and post-irradiation graphite was conducted to determine the chemical environment and quantity of C-14 and its precursors via the use of surface sensitive characterization techniques. Scanning Electron Microscopy (SEM) was used to evaluate the morphological features of graphite samples. The concentration, chemical composition, and bonding characteristics of C-14 and its precursors were determined through X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (SIMS), and Energy Dispersive X-ray Analysis Spectroscopy (EDX). Results of post-irradiation characterization of these materials indicate a variety of surface functional groups containing carbon, oxygen, nitrogen and hydrogen. During thermal treatment, irradiated graphite samples are heated in the presence of an inert carrier gas (with or without oxidant gas), which

  12. Soil carbon storage following road removal and timber harvesting in redwood forests

    USGS Publications Warehouse

    Seney, Joseph; Madej, Mary Ann

    2015-01-01

    Soil carbon storage plays a key role in the global carbon cycle and is important for sustaining forest productivity. Removal of unpaved forest roads has the potential for increasing carbon storage in soils on forested terrain as treated sites revegetate and soil properties improve on the previously compacted road surfaces. We compared soil organic carbon (SOC) content at several depths on treated roads to SOC in adjacent second-growth forests and old-growth redwood forests in California, determined whether SOC in the upper 50 cm of soil varies with the type of road treatment, and assessed the relative importance of site-scale and landscape-scale variables in predicting SOC accumulation in treated road prisms and second-growth redwood forests. Soils were sampled at 5, 20, and 50 cm depths on roads treated by two methods (decommissioning and full recontouring), and in adjacent second-growth and old-growth forests in north coastal California. Road treatments spanned a period of 32 years, and covered a range of geomorphic and vegetative conditions. SOC decreased with depth at all sites. Treated roads on convex sites exhibited higher SOC than on concave sites, and north aspect sites had higher SOC than south aspect sites. SOC at 5, 20, and 50 cm depths did not differ significantly between decommissioned roads (treated 18–32 years previous) and fully recontoured roads (treated 2–12 years previous). Nevertheless, stepwise multiple regression models project higher SOC developing on fully recontoured roads in the next few decades. The best predictors for SOC on treated roads and in second-growth forest incorporated aspect, vegetation type, soil depth, lithology, distance from the ocean, years since road treatment (for the road model) and years since harvest (for the forest model). The road model explained 48% of the variation in SOC in the upper 50 cm of mineral soils and the forest model, 54%

  13. Fluxes of carbon, phosphorylation, and redox intermediates during growth of Saccharomyces cerevisiae on different carbon sources

    SciTech Connect

    Cortassa, S.; Aon, J.C.; Aon, M.A.

    1995-07-20

    In the present work the authors developed a method for estimating anabolic fluxes when yeast are growing on various carbon substrates (glucose, glycerol, lactate, pyruvate, acetate, or ethanol) in minimal medium. Fluxes through the central amphibolic pathways were calculated from the product of the total required amount of a specified carbon intermediate times the growth rate. The required amount of each carbon intermediate was estimated from the experimentally determined macromolecular composition of cells grown in each carbon source and the monomer composition of macromolecules. Substrates sharing most metabolic pathways such as ethanol and acetate, despite changes in the macromolecular composition, namely carbohydrate content, did not show large variations in the overall fluxes through the main amphibolic pathways. For instance, in order to supply anabolic precursors to sustain growth rates in the range of 0.16/h to 0.205/h, similar large fluxes through Acetyl CoA synthase were required by acetate or ethanol. The V{sub max} activities of key enzymes of the main amphibolic pathways measured in permeabilized yeast cells allowed to confirm, qualitatively, the operation of those pathways for all substrates and were consistent on most substrates with the estimate fluxes required to sustain growth.

  14. Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in Northeast China

    PubMed Central

    Liu, Yu; Chen, Zhonglin; Shen, Jimin

    2013-01-01

    The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impacts on public health. This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoir—the new and important water source of Harbin city in Northeast China. As drinking water is a major source for human exposure to PAEs, the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed. The results demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderate, ranging from 355.8 to 9226.5 ng/L, with the mean value of 2943.1 ng/L. DBP and DEHP dominated the PAE concentrations, which ranged from 52.5 to 4498.2 ng/L and 128.9 to 6570.9 ng/L, respectively. The occurrence and concentrations of these compounds were heavily spatially dependent. Meanwhile, the results on the waterworks samples suggested no significant differences in PAE levels with the input of the raw waters. Without effective and stable removal of PAEs after the conventional drinking water treatment in the waterworks (25.8% to 76.5%), the risks posed by PAEs through drinking water ingestion were still existing, which should be paid special attention to the source control in the Mopanshan Reservoir and some advanced treatment processes for drinking water supplies. PMID:23577281

  15. Comparison between sequential and simultaneous application of activated carbon with membrane bioreactor for trace organic contaminant removal.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Kang, Jinguo; Nghiem, Long D; Price, William E; Guo, Wenshan; Ngo, Huu H; Tung, Kuo-Lun

    2013-02-01

    The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR-GAC) and simultaneous application of PAC within MBR (PAC-MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50-70%, in MBR-GAC and PAC-MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC-MBR appears to be a better option than MBR-GAC treatment. PMID:23313687

  16. MASS-REMOVAL AND MASS-FLUX-REDUCTION BEHAVIOR FOR IDEALIZED SOURCE ZONES WITH HYDRAULICALLY POORLY-ACCESSIBLE IMMISCIBLE LIQUID

    SciTech Connect

    Brusseau, M. L.; Difilippo, Erica L.; marble, justin C.; Oostrom, Mart

    2008-04-01

    A series of flow-cell experiments was conducted to investigate aqueous dissolution and mass-removal behavior for systems wherein immiscible liquid was non-uniformly distributed in physically heterogeneous source zones. The study focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems for which immiscible liquid is poorly accessible to flowing water. Two idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. The results showed that significant reductions in mass flux occurred at relatively moderate mass-removal fractions for all systems. Conversely, minimalmass flux reduction occurred until a relatively large fraction of mass (>80%) was removed for the control experiment, which was designed to exhibit ideal mass removal. In general, mass flux reduction was observed to follow an approximately one-to-one relationship with mass removal. Two methods for estimating mass-flux-reduction/mass-removal behavior, one based on system-indicator parameters (ganglia-to-pool ratio) and the other a simple mass-removal function, were used to evaluate the measured data. The results of this study illustrate the impact of poorly accessible immiscible liquid on mass-removal and mass-flux processes, and the difficulties posed for estimating mass-flux-reduction/mass-removal behavior.

  17. Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons.

    PubMed

    Hajizadeh, Yaghoub; Onwudili, Jude A; Williams, Paul T

    2011-06-01

    The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275°C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 μg I-TEQ kg(-1) toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 μg I-TEQ kg(-1) in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases. PMID:21334872

  18. Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons

    SciTech Connect

    Hajizadeh, Yaghoub; Onwudili, Jude A.; Williams, Paul T.

    2011-06-15

    The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275 deg. C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 {mu}g I-TEQ kg{sup -1} toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 {mu}g I-TEQ kg{sup -1} in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases.

  19. Special role of corn flour as an ideal carbon source for aerobic denitrification with minimized nitrous oxide emission.

    PubMed

    Zhu, Shuangyue; Zheng, Maosheng; Li, Can; Gui, Mengyao; Chen, Qian; Ni, Jinren

    2015-06-01

    Much effort has been made for reducing nitrous oxide (N2O) emission in wastewater treatment processes. This paper presents an interesting way to minimize N2O in aerobic denitrification by strain Pseudomonas stutzeri PCN-1 with help of corn flour as cheaper additional carbon source. Experimental results showed that maximal N2O accumulation by strain PCN-1 was only 0.02% of removed nitrogen if corn flour was used as sole carbon source, which was significantly reduced by 52.07-99.81% comparing with others such as succinate, glucose, acetate and citrate. Sustained release of reducing sugar from starch and continuous expression of nosZ coding for N2O reductase contributed to the special role of corn flour as the ideal carbon source for strain PCN-1. Further experiments in sequencing batch reactors (SBRs) demonstrated similarly efficient nitrogen removal with much less N2O emission due to synergy of the novel strain and activated sludge, which was then confirmed by quantitative PCR analysis. PMID:25802047

  20. Effect of fermentation liquid from food waste as a carbon source for enhancing denitrification in wastewater treatment.

    PubMed

    Zhang, Yongmei; Wang, Xiaochang C; Cheng, Zhe; Li, Yuyou; Tang, Jialing

    2016-02-01

    Food wastes were used for anaerobic fermentation to prepare carbon sources for enhancing nitrogen removal in wastewater treatment. Under anaerobic conditions without pH adjustment, the fermentation liquid from food wastes (FLFW) with a high organic acid content was produced at room temperature (25 °C) and initial solid concentration of 13%. Using FLFW as the sole carbon source of artificial wastewater for biological treatment by sequence batch operation, maximized denitrification (with a denitrification rate of V(DN) = 12.89 mg/gVSS h and a denitrification potential of P(DN) = 0.174 gN/gCOD) could be achieved at a COD/TN ratio of 6. The readily biodegradable fraction in the FLFW was evaluated as 58.35%. By comparing FLFW with glucose and sodium acetate, two commonly used chemical carbon sources, FLFW showed a denitrification result similar to sodium acetate but much better than glucose in terms of total nitrogen removal, V(DN), P(DN), organic matter consumption rate (V(COD)) and heterotrophy anoxic yield coefficient (Y(H)). PMID:26408975

  1. Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source

    SciTech Connect

    Vevera, Bradley J; Hyres, James W; McClintock, David A; Riemer, Bernie

    2014-01-01

    Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.

  2. Tritium Removal from Codeposits on Carbon Tiles by a Scanning Laser

    SciTech Connect

    C.H. Skinner; C.A. Gentile; A. Carpe; G. Guttadora; S. Langish; K.M. Young; W.M. Shu; and H. Nakamura

    2001-09-28

    A novel method for tritium release has been demonstrated on codeposited layers on graphite and carbon-fiber-composite tiles from the Tokamak Fusion Test Reactor (TFTR). A scanning continuous wave Nd laser beam heated the codeposits to a temperature of 1200-2300 degrees C for 10 to 200 milliseconds in an argon atmosphere. The temperature rise of the codeposit was significantly higher than that of the manufactured tile material (e.g., 1770 degrees C cf. 1080 degrees C). A major fraction of tritium was thermally desorbed with minimal change to the surface appearance at a laser intensity of 8 kW/cm(superscript ''2''), peak temperatures above 1230 degrees C and heating duration 10-20 milliseconds. In two experiments, 46% and 84% of the total tritium was released during the laser scan. The application of this method for tritium removal from a tokamak reactor appears promising and has significant advantages over oxidative techniques.

  3. Apparent removal of the transient tracer carbon tetrachloride from anoxic seawater

    SciTech Connect

    Krysell, M.; Fogelqvist, E.; Tanhua, T. |

    1994-11-01

    Two chlorofluorocarbons (CFC-11 and carbon tetrachloride, CCl4) widely used as tracers for dating water masses, were measured in the Gotland Basin of the Baltic Sea. At the time of the survey, the bottom water of the basin had remained stagnant for 15 years and anoxic for about the same period of time, and the concentrations of both CFC-11 and CCl4 decrease dramatically with depth below the mixed layer. Furthermore, the ratio of CFC-11 to CCl4 increases with depth under the mixed layer along with a steep decrease in oxygen concentration. This is contrary to what would be expected from the atmospheric histories. The most plausible explanation for this is that there is a mechanism whereby the CCl4 is removed from the water mass under anoxic and suboxide conditions.

  4. Electro-catalytic oxidation device for removing carbon from a fuel reformate

    DOEpatents

    Liu, Di-Jia

    2010-02-23

    An electro-catalytic oxidation device (ECOD) for the removal of contaminates, preferably carbonaceous materials, from an influent comprising an ECOD anode, an ECOD cathode, and an ECOD electrolyte. The ECOD anode is at a temperature whereby the contaminate collects on the surface of the ECOD anode as a buildup. The ECOD anode is electrically connected to the ECOD cathode, which consumes the buildup producing electricity and carbon dioxide. The ECOD anode is porous and chemically active to the electro-catalytic oxidation of the contaminate. The ECOD cathode is exposed to oxygen, and made of a material which promotes the electro-chemical reduction of oxygen to oxidized ions. The ECOD electrolyte is non-permeable to gas, electrically insulating and a conductor to oxidized. The ECOD anode is connected to the fuel reformer and the fuel cell. The ECOD electrolyte is between and in ionic contact with the ECOD anode and the ECOD cathode.

  5. Prevention of hyaline membrane disease in premature lambs by apneic oxygenation and extracorporeal carbon dioxide removal.

    PubMed

    Pesenti, A; Kolobow, T; Buckhold, D K; Pierce, J E; Huang, H; Chen, V

    1982-01-01

    Hyaline membrane disease is found only in lungs where pulmonary ventilation has been established, i.e. after birth. We delivered eleven fetal lambs of a gestational age of 128-130 days but instead kept their lungs in total apnea and inflated to constant pressure, while removing all metabolically produced carbon dioxide with an extracorporeal membrane lung. Oxygen was provided by the membrane lung, and by apneic oxygenation through the natural lungs. Hence, arterial blood gases remained always normal, without any pulmonary ventilation. After 6-66 h the lungs had sufficiently cleared to allow normal mechanical pulmonary ventilation in 10 our of 11 lambs so treated. In a control group treated with mechanical ventilation alone, five of seven lambs died within the first 24 h of severe hyaline membrane disease. PMID:6799556

  6. Developing real-time control software for Space Station Freedom carbon dioxide removal

    NASA Technical Reports Server (NTRS)

    Rowe, Steven A.; Morando, Alexander R.; Johnson, Jim

    1991-01-01

    This paper presents AiResearch experience to date in using the NASA/Boeing Application Generator (AG) to develop real-time control systems for the Carbon Dioxide Removal Assembly (CDRA) in Work Package 01. The AG provides an integrated design and development tool encompassing: system analysis, modeling, control law design, simulation, code generation, real-time hardware-in-the-loop simulation and operation, and documentation. This allows rapid interactive prototyping of real-time control systems in a single, integrated, environment. Advantages and disadvantages of using the AG for real-time control system development will be addressed, with the CDRA specification to delivery cycle serving as a basis for discussion. Suggestions for improving the AG are offered and observations on its potential as a top-level system specification tool are made.

  7. Removal of trihalomethanes from aqueous solution through armchair carbon nanotubes: a molecular dynamics study.

    PubMed

    Azamat, Jafar; Khataee, Alireza; Joo, Sang Woo; Yin, Binfeng

    2015-04-01

    Molecular dynamics simulations were performed to investigate the removal of trihalomethanes (THMs) including CH3Cl, CH2Cl2 and CHCl3 from aqueous solutions by armchair carbon nanotubes (CNTs) under induced pressure. The studied system involved the armchair CNTs embedded between two graphene sheets with an aqueous solution of THMs in the simulation box. An external pressure was applied to the system along the z-axis of the simulation box. Six types of armchair CNTs with different diameter were used in this work, included (4,4), (5,5), (6,6), (7,7), (8,8) and (9,9) CNTs. The results of molecular dynamics simulation display that the armchair CNTs behave differently relative to THMs and water molecules. The permeation of THMs and water molecules through the armchair CNTs was dependent on the diameter of CNTs and the applied pressure. PMID:25682360

  8. Development of Carbon Dioxide Removal Systems for Advanced Exploration Systems 2015-2016

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Coker, Robert; Howard, David; Peters, Warren; Watson, David; Cmarik, Gregory; Miller, Lee A.

    2016-01-01

    A long-term goal for NASA is to enable crewed missions to Mars: first to the vicinity of Mars, and then to the Mars surface. These missions present new challenges for all aspects of spacecraft design in comparison with the International Space Station, as resupply is unavailable in the transit phase, and early return is not possible. Additionally, mass, power, and volume must be minimized for all phases to reduce propulsion needs. Mass reduction is particularly crucial for Mars surface landing and liftoff due to the challenges inherent in these operations for even much smaller payloads. In this paper we describe current and planned developments in the area of carbon dioxide removal to support future crewed Mars missions. Activities are also described that apply to both the resolution of anomalies observed in the ISS CDRA and the design of life support systems for future missions.

  9. Development of Carbon Dioxide Removal Systems for Advanced Exploration Systems 2014-2015

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Coker, Robert; Huff, Timothy L.; Gatens, Robyn; Miller, Lee A.; Stanley, Christine

    2015-01-01

    A long-term goal for NASA is to enable crewed missions to Mars: first to the vicinity of Mars, and then to the Mars surface. These missions present new challenges for all aspects of spacecraft design in comparison with the International Space Station, as resupply is unavailable in the transit phase, and early return is not possible. Additionally, mass, power, and volume must be minimized for all phases to reduce propulsion needs. Mass reduction is particularly crucial for Mars surface landing and liftoff due to the challenges inherent in these operations for even much smaller payloads. In this paper we describe current and planned developments in the area of carbon dioxide removal to support future crewed Mars missions. Activities are also described that apply to both the resolution of anomalies observed in the ISS CDRA and the design of life support systems for future missions.

  10. Anthropogenic carbon dioxide source regions observed from space

    NASA Astrophysics Data System (ADS)

    Schneising, Oliver; Heymann, Jens; Buchwitz, Michael; Reuter, Maximilian; Bovensmann, Heinrich; Burrows, John P.

    2013-04-01

    Urban areas, which are home to the majority of today's world population, are responsible for more than two-thirds of the global energy-related carbon dioxide emissions. Given the ongoing demographic growth and rising energy consumption in metropolitan regions particularly in the developing world, urban-based emissions are expected to further increase in the future. As a consequence, monitoring and independent verification of reported anthropogenic emissions is becoming more and more important. It is demonstrated using CO2 column-averaged mole fraction data retrieved from the SCIAMACHY instrument onboard ENVISAT that anthropogenic CO2 emissions can be detected from space and that emission trends might be tracked using satellite observations. This is promising with regard to future satellite missions with high spatial resolution and wide swath imaging capability aiming at constraining anthropogenic emissions down to the point-source scale. By subtracting retrieved background values from those retrieved over urban areas the regional contrasts are quantified and significant CO2 enhancements are found for several anthropogenic source regions around the world. The order of magnitude of the enhancements is in agreement with what is expected for anthropogenic CO2 signals. The validity of the retrieved spatial enhancement patterns and of the temporal trends of the retrieved enhancements is assessed by comparison with anthropogenic emissions from the Emission Database for Global Atmospheric Research (EDGAR).

  11. Removal of oil droplets from contaminated water using magnetic carbon nanotubes.

    PubMed

    Wang, Haitao; Lin, Kun-Yi; Jing, Benxin; Krylova, Galyna; Sigmon, Ginger E; McGinn, Paul; Zhu, Yingxi; Na, Chongzheng

    2013-08-01

    Water contaminated by oil and gas production poses challenges to the management of America's water resources. Here we report the design, fabrication, and laboratory evaluation of multi-walled carbon nanotubes decorated with superparamagnetic iron-oxide nanoparticles (SPIONs) for oil-water separation. As revealed by confocal laser-scanning fluorescence microscopy, the magnetic carbon nanotubes (MCNTs) remove oil droplets through a two-step mechanism, in which MCNTs are first dispersed at the oil-water interface and then drag the droplets with them out of water by a magnet. Measurements of removal efficiency with different initial oil concentration, MCNT dose, and mixing time show that kinetics and equilibrium of the separation process can be described by the Langmuir model. Separation capacity qt is a function of MCNT dose m, mixing time t, and residual oil concentration Ce at equilibrium: [Formula in text] where qmax, kw, and K are maximum separation capacity, wrapping rate constant, and equilibrium constant, respectively. Least-square regressions using experimental data estimate qmax = 6.6(± 0.6) g-diesel g-MCNT(-1), kw = 3.36(± 0.03) L g-diesel(-1) min(-1), and K = 2.4(± 0.2) L g-diesel(-1). For used MCNTs, we further show that over 80% of the separation capacity can be restored by a 10 min wash with 1 mL ethanol for every 6 mg MCNTs. The separation by reusable MCNTs provides a promising alternative strategy for water treatment design complementary to existing ones such as coagulation, adsorption, filtration, and membrane processes. PMID:23582309

  12. Removing Complications of a Dominant Broad Age Spectrum Source: A New Approach to the Mixing of Detrital Zircons.

    NASA Astrophysics Data System (ADS)

    Wissink, G.; Hoke, G. D.

    2014-12-01

    Detrital zircons are often considered the panacea of provenance analysis but are often limited to inquiry based solely on the presence or absence of populations and thus restricted to qualitative comparisons. However, if one broad age spectrum source dominates a detrital dataset other sources may be obscured. We present a method for removing a broad age spectrum source through a process of randomly drawing grains from the dominant source, pairing them with sample grains and removing matched aged grains. This results in a residual population representing all remaining unassociated ages, which can then be compared to other potential sources using PDP crossplot and likeness comparisons. The sources best matching our post-removal sample are resampled in varying proportions, with the dominant, broad age spectrum source, to recreate the pre-subtraction sample by maximizing the population comparison tests. We test our method with a synthetic dataset of 18, 10,000-grain 'sandstone' populations created from 6 easily differentiable sources and 1 complex source representing the dominant, broad age spectrum source. Synthetic detrital zircon age populations are created by randomly selecting from each of the synthetic populations. This method was able to consistently determine the correct sources and their mixing proportions to within ±10% of the original artificial sandstone proportions. Covariance between the two comparison tests also shows improvement relative to their pre-removal counterparts. Previously published detrital zircon age data from modern sediment samples of the Yangtze River (He et al., 2013) show a dominance of ages commonly attributed to the Triassic Songpan Ganze Terrane, which has a broad age spectrum. We applied our method to these Yangtze age populations in conjunction with 35 potential sources units compiled and consolidated from the literature. Applying this technique to modern Chinese sediments identifies previously unknown contributing sources and

  13. Selective and Scalable Chemical Removal of Thin Single-Walled Carbon Nanotubes from their Mixtures with Double-Walled Carbon Nanotubes.

    PubMed

    Komínková, Zuzana; Valeš, Václav; Kalbáč, Martin

    2015-11-01

    Double-walled carbon nanotubes (DWCNTs) are materials in high demand due to their superior properties. However, it is very challenging to prepare DWCNTs samples of high purity. In particular, the removal of single-walled carbon nanotubes (SWCNTs) contaminants is a major problem. Here, a procedure for a selective removal of thin-diameter SWCNTs from their mixtures with DWCNTs by lithium vapor treatment is investigated. The results are evaluated by Raman spectroscopy and in situ Raman spectroelectrochemistry. It is shown that the amount of SWCNTs was reduced by about 35 % after lithium vapor treatment of the studied SWCNTs-DWCNTs mixture. PMID:26358882

  14. Coupling Aggressive Mass Removal with Microbial Reductive Dechlorination for Remediation of DNAPL Source Zones: A Review and Assessment

    PubMed Central

    Christ, John A.; Ramsburg, C. Andrew; Abriola, Linda M.; Pennell, Kurt D.; Löffler, Frank E.

    2005-01-01

    The infiltration of dense non-aqueous-phase liquids (DNAPLs) into the saturated subsurface typically produces a highly contaminated zone that serves as a long-term source of dissolved-phase groundwater contamination. Applications of aggressive physical–chemical technologies to such source zones may remove > 90% of the contaminant mass under favorable conditions. The remaining contaminant mass, however, can create a rebounding of aqueous-phase concentrations within the treated zone. Stimulation of microbial reductive dechlorination within the source zone after aggressive mass removal has recently been proposed as a promising staged-treatment remediation technology for transforming the remaining contaminant mass. This article reviews available laboratory and field evidence that supports the development of a treatment strategy that combines aggressive source-zone removal technologies with subsequent promotion of sustained microbial reductive dechlorination. Physical–chemical source-zone treatment technologies compatible with posttreatment stimulation of microbial activity are identified, and studies examining the requirements and controls (i.e., limits) of reductive dechlorination of chlorinated ethenes are investigated. Illustrative calculations are presented to explore the potential effects of source-zone management alternatives. Results suggest that, for the favorable conditions assumed in these calculations (i.e., statistical homogeneity of aquifer properties, known source-zone DNAPL distribution, and successful bioenhancement in the source zone), source longevity may be reduced by as much as an order of magnitude when physical–chemical source-zone treatment is coupled with reductive dechlorination. PMID:15811838

  15. Towards a Carbon Nanotube Ionization Source for Planetary Atmosphere Exploration

    NASA Astrophysics Data System (ADS)

    Oza, A. V.; Leblanc, F.; Berthelier, J. J.; Becker, J.; Coulomb, R.; Gilbert, P.; Hong, N. T.; Lee, S.; Vettier, L.

    2015-12-01

    The characterization of planetary exospheres today, relies on the development of a highly efficient ionization source, due to the scant neutral molecules (n < 108 cm -3) present in diffuse planetary coronae. These tenuous atmospheres provide insight on to physical processes known to occur such as: space weathering, magneto-atmosphere interactions, as well as atmospheric escape mechanisms, all of which are being heavily investigated via current 3D Monte Carlo simulations (Turc et al. 2014, Leblanc et al. 2016 in prep) at LATMOS. Validation of these studies will rely on in-situ observations in the coming decades. Neutral detection strongly depends on electron-impact ionization which via conventional cathode-sources, such as thermal filaments (heated up to 2000 K), may only produce the target ionization essential for energy-measurements with large power consumption. Carbon nanotubes (CNTs) however are ideal low-power, cold cathodes, when subject to moderate electric fields (E ~ 1 MV / m). We present our current device, a small CNT chip, of emission area 15 mm2, emitting electrons that pass through an anode grid and subsequent electrostatic analyzer. The device currently extracts hundreds of µAmperes with applied external voltages ~ -150 Volts, approaching minimum power consumption < 0.1 Watts. The 3D modeling of field effect electrons ionizing a standard influx of neutrals is shown, using the multiphysics suite COMSOL. To better anticipate the species an ideal in-situ spacecraft equipped with such an ionization source would observe, we discuss Europa's exosphere. Europa's environment is largely shaped by the Jovian plasma sputtering the icy regolith with heavy ions and electrons (keV < E < MeV), producing predominately molecular oxygen (Johnson et al. 2002).

  16. Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow.

    PubMed

    Ghaedi, M; Hekmati Jah, A; Khodadoust, S; Sahraei, R; Daneshfar, A; Mihandoost, A; Purkait, M K

    2012-05-01

    Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%. PMID:22306446

  17. Cadmium telluride nanoparticles loaded on activated carbon as adsorbent for removal of sunset yellow

    NASA Astrophysics Data System (ADS)

    Ghaedi, M.; Hekmati Jah, A.; Khodadoust, S.; Sahraei, R.; Daneshfar, A.; Mihandoost, A.; Purkait, M. K.

    2012-05-01

    Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

  18. Removal of trichloroethylene by zerovalent iron/activated carbon derived from agricultural wastes.

    PubMed

    Su, Yuh-fan; Cheng, Yu-ling; Shih, Yang-hsin

    2013-11-15

    Activated carbon (AC) and zerovalent iron (ZVI) have been widely used in the adsorption and dehalogenation process, respectively, for the removal of organic compounds in environmental treatments. This study aims to prepare ZVI/AC derived from an agricultural waste, coir pith, through simple one-step pyrolysis. The effect of activation temperature and time on the surface area, iron content, and zerovalent iron ratio of ZVI/AC was systemically investigated. The results indicated that the activation of AC by FeSO4 significantly increased surface area of AC and distributed elemental iron over the AC. The X-ray diffraction (XRD), electron spectroscopy for chemical analysis (ESCA), and X-ray absorption near edge structure (XANES) spectra of ZVI/AC revealed that zerovalent iron was present. As compared to AC without FeSO4 activation, ZVI/AC increased the trichloroethylene removal rate constant by 7 times. The dechlorination ability of ZVI/AC was dominated by the zerovalent iron content. We have shown that lab-made ZVI/AC from coir pith can effectively adsorb and dehalogenate the chlorinated compounds in water. PMID:23994578

  19. Removal of lead(II) from aqueous solutions using carbonate hydroxyapatite extracted from eggshell waste.

    PubMed

    Liao, Dexiang; Zheng, Wei; Li, Xiaoming; Yang, Qi; Yue, Xiu; Guo, Liang; Zeng, Guangming

    2010-05-15

    Carbonate hydroxyapatite (CHAP) synthesized from eggshell waste was used for removing lead ion from aqueous solutions. The effects of pH, contact time and initial concentration were studied in batch experiments. The maximum uptake of lead ion was obtained at pH 6.0. Adsorption equilibrium was established by 60 min. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were applied to study the kinetics of the sorption processes. The pseudo-second order kinetic model provided the best correlation (R(2)>0.9991) of the used experimental data compared to the pseudo-first order and intraparticle diffusion kinetic models. The adsorption of lead ion by CHAP increased as the initial concentration of lead ion increased in the medium. The maximum lead ion adsorbed was found to be 101 mg g(-1). It was found that the adsorption of Pb(II) on CHAP was correlated well (R(2)=0.9995) with the Langmuir equation as compared to Freundlich isotherm equation under the concentration range studied. This study indicated that CHAP could be used as an efficient adsorbent for removal of lead ion from aqueous solution. PMID:20042291

  20. Magnetic recovery of modified activated carbon powder used for removal of endocrine disruptors present in water.

    PubMed

    Borghi, Chiara Caterina; Fabbri, Massimo

    2014-01-01

    This paper was aimed at studying sustainable solutions for the treatment of water polluted by octylphenols and nonylphenols that are xenoextrogen compounds affecting human health and dangerous for the aquatic environment. We studied the removal of 4-octylphenol and 4-n-nonylphenol with concentrations of the order of 5-10 mg/l on a laboratory scale. A mixing time of 10 min with 0.1 g/l of magnetic-activated carbons (MACs) was enough to obtain 95 +/- 5% adsorption of both 4-octylphenol and 4-n-nonylphenol. The adsorption of the surfactants IGEPAL CO-630 and TRITON X-100, which are precursors of branched 4-nonylphenol and the carcinogenic 4-tert-octylphenol, respectively, was also studied using the same technique. For concentrations between 2 and 10mg/l of these alkylphenols ethoxylated, after 10min mixing with 0.5 g/l of MACs, a 95 +/- 5% adsorption was obtained. A 97 +/- 1% removal of MACs was achieved after 10min of continuous-flow magnetic filtration (14.5 l/min). The filter used was made of SUS440C magnetic steel spheres. Srm-Co permanent magnets provided a uniform flux density field of about 500 mT. PMID:24645486

  1. Pilot-scale study of powdered activated carbon recirculation for micropollutant removal.

    PubMed

    Meinel, F; Sperlich, A; Jekel, M

    2016-01-01

    Adsorption onto powdered activated carbon (PAC) is a promising technique for the removal of organic micropollutants (OMPs) from treated wastewater. To enhance the adsorption efficiency, PAC is recycled back into the adsorption stage. This technique was examined in pilot scale in comparison to a reference without recirculation. Coagulation with Fe(3+) was carried out simultaneously to adsorption. Extensive OMP measurements showed that recirculation significantly increased OMP eliminations. Thus, significant PAC savings were feasible. The PAC concentration in the contact reactor proved to be an important operating parameter that can be surrogated by the easily measurable total suspended solids (TSS) concentration. OMP eliminations increased with increasing TSS concentrations. At 20 mg PAC L(-1) and 2.8 g TSS L(-1) in the contact reactor, well-adsorbable carbamazepine was eliminated by 97%, moderately adsorbable diclofenac was eliminated by 92% and poorly-adsorbable acesulfame was eliminated by 54% in comparison to 49%, 35% and 18%, respectively, without recirculation. The recirculation system represents an efficient technique, as the PAC's adsorption capacity is practically completely used. Small PAC dosages yield high OMP eliminations. Poorly-adsorbable gabapentin was eliminated to an unexpectedly high degree. A laboratory-scale biomass inhibition study showed that aerobic biodegradation removed gabapentin in addition to adsorption. PMID:27533867

  2. Selective Removal of Demineralization Using Near Infrared Cross Polarization Reflectance and a Carbon Dioxide Laser

    PubMed Central

    Chan, Kenneth H.; Fried, Daniel

    2012-01-01

    Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates. PMID:24357906

  3. Tertiary ethanolamines more economical for removal of H/sub 2/S and carbon dioxide

    SciTech Connect

    Riesenfeld, F.C.; Brocoff, J.C.

    1986-09-01

    At present, it appears that tertiary ethanolamines, if properly used, are substantially more economical for a variety of selective and nonselective gas-purification operations than primary and secondary ethanolamines. Examples of such operations are: selective H/sub 2/S removal from natural and synthesis gases, absorption of high concentrations of CO/sub 2/ from gas streams available at high pressure, and selective H/sub 2/S removal from waste gases, e.g., Claus tail gas. The principal advantages of tertiary over primary and secondary ethanolamines are, besides their selectivity for H/sub 2/S, their lower heat of reaction with the acid gases (and consequent lower heat requirements for solution stripping); their lower vapor pressure, permitting use of high concentration and high capacity in the treating solution; their nonreactivity with COS and CS/sub 2/, avoiding formation of nonregenerable compounds; and their lower corrosiveness, allowing carbon-steel construction throughout the plant. If these features are combined, it becomes clear that tertiary ethanolamines are the proper choice for many gas-purification systems. Among the tertiary ethanolamines, methyldiethanolamine (MDEA) is the preferred amine, although triethanolamine (TEA) is also useful for CO/sub 2/ absorption.

  4. Thermal analysis for laser selective removal of metallic single-walled carbon nanotubes

    SciTech Connect

    Song, Jizhou; Li, Yuhang; Du, Frank; Xie, Xu; Rogers, John A.; Huang, Yonggang

    2015-04-28

    Single-walled carbon nanotubes (SWNTs) have been envisioned as one of the best candidates for future semiconductors due to their excellent electrical properties and ample applications. However, SWNTs grow as mixture of both metallic and semiconducting tubes and this heterogeneity hampers their practical applications. Laser radiation shows promises to remove metallic SWNTs (m-SWNTs) in air under an appropriate condition. We established a scaling law, validated by finite element simulations, for the temperature rise of m-SWNTs under a pulsed laser with a Gaussian spot. It is shown that the maximum normalized m-SWNT temperature rise only depends on two non-dimensional parameters: the normalized pulse duration time and the normalized interfacial thermal resistance. In addition, the maximum temperature rise is inversely proportional to the square of spot size and proportional to the incident laser power. These results are very helpful to understand the underlying physics associated with the removal process and provides easily interpretable guidelines for further optimizations.

  5. Selective removal of demineralization using near infrared cross polarization reflectance and a carbon dioxide laser

    NASA Astrophysics Data System (ADS)

    Chan, Kenneth H.; Fried, Daniel

    2012-01-01

    Lasers can ablate/remove tissue in a non-contact mode of operation and a pulsed laser beam does not interfere with the ability to image the tooth surface, therefore lasers are ideally suited for integration with imaging devices for image-guided ablation. Laser energy can be rapidly and efficiently delivered to tooth surfaces using a digitally controlled laser beam scanning system for precise and selective laser ablation with minimal loss of healthy tissues. Under the appropriate irradiation conditions such laser energy can induce beneficial chemical and morphological changes in the walls of the drilled cavity that can increase resistance to further dental decay and produce surfaces with enhanced adhesive properties to restorative materials. Previous studies have shown that images acquired using near-IR transillumination, optical coherence tomography and fluorescence can be used to guide the laser for selective removal of demineralized enamel. Recent studies have shown that NIR reflectance measurements at 1470-nm can be used to obtain images of enamel demineralization with very high contrast. The purpose of this study was to demonstrate that image guided ablation of occlusal lesions can be successfully carried out using a NIR reflectance imaging system coupled with a carbon dioxide laser operating at 9.3-μm with high pulse repetition rates.

  6. Modeling simultaneous carbon and nitrogen removal (SCNR) in anaerobic/anoxic reactor treating domestic wastewater.

    PubMed

    Mendes, Carlos; Esquerre, Karla; Queiroz, Luciano Matos

    2016-07-15

    This paper presents a mathematical model based on the Anaerobic Digestion Model No. 1 (ADM1) to simulate the effects of nitrate concentration and hydraulic retention time (HRT) on the simultaneous carbon and nitrogen removal (SCNR) in anaerobic/anoxic reactor treating domestic wastewater. The model was calibrated using previously published experimental data obtained from anaerobic batch tests for different COD/ [Formula: see text] ratios. Model simulations were performed to predict the SCNR in a completely mixed reactor (CSTR) operating under mesophilic conditions (35 °C). Six different scenarios were evaluated to investigate the performance of the SCNR based on typical influent characteristics of domestic wastewater. The variables analyzed were chemical oxygen demand (COD) removal, nitrate concentration, methane production, nitrogen gas, volatile fatty acids (VFA) concentration, pH and percentage of COD used by the denitrifying and methanogenic microorganisms. The HRT was decreased stepwise from 15 to 4 h. The results indicate that Scenario (S5) with a COD/ [Formula: see text] ratio equal to 10 and an HRT equal to 15 h ensures the occurrence of the stable SCNR. Furthermore, the accumulation of denitrification intermediates and a significant reduction in the biogas production when the organic matter is limited was verified. PMID:27088208

  7. Arsenic removal from aqueous solutions by adsorption onto iron oxide/activated carbon magnetic composite

    PubMed Central

    2014-01-01

    In this work the adsorption features of activated carbon and the magnetic properties of iron oxides were combined in a composite to produce magnetic adsorbent. Batch experiments were conducted to study the adsorption behavior of arsenate onto the synthetic magnetic adsorbent. The effects of initial solution pH, contact time, adsorbent dosage and co-existing anionic component on the adsorption of arsenate were investigated. The results showed that the removal percentage of arsenate could be over 95% in the conditions of adsorbent dosage 5.0 g/L, initial solution pH 3.0-8.0, and contact time 1 h. Under the experimental conditions, phosphate and silicate caused greater decrease in arsenate removal percentage among the anions, and sulfate had almost no effect on the adsorption of arsenate. Kinetics study showed that the overall adsorption rate of arsenate was illustrated by the pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the arsenate adsorption data was tested. Both the models adequately describe the experimental data. Moreover, the magnetic composite adsorbent could be easily recovered from the medium by an external magnetic field. It can therefore be potentially applied for the treatment of water contaminated by arsenate. PMID:24602339

  8. Effect of air-assisted backwashing on the performance of an anaerobic fixed-bed bioreactor that simultaneously removes nitrate and arsenic from drinking water sources.

    PubMed

    Upadhyaya, Giridhar; Clancy, Tara M; Snyder, Kathryn V; Brown, Jess; Hayes, Kim F; Raskin, Lutgarde

    2012-03-15

    Contaminant removal from drinking water sources under reducing conditions conducive for the growth of denitrifying, arsenate reducing, and sulfate reducing microbes using a fixed-bed bioreactor may require oxygen-free gas (e.g., N2 gas) during backwashing. However, the use of air-assisted backwashing has practical advantages, including simpler operation, improved safety, and lower cost. A study was conducted to evaluate whether replacing N2 gas with air during backwashing would impact performance in a nitrate and arsenic removing anaerobic bioreactor system that consisted of two biologically active carbon reactors in series. Gas-assisted backwashing, comprised of 2 min of gas injection to fluidize the bed and dislodge biomass and solid phase products, was performed in the first reactor (reactor A) every two days. The second reactor (reactor B) was subjected to N2 gas-assisted backwashing every 3-4 months. Complete removal of 50 mg/L NO3- was achieved in reactor A before and after the switch from N2-assisted backwashing (NAB) to air-assisted backwashing (AAB). Substantial sulfate removal was achieved with both backwashing strategies. Prolonged practice of AAB (more than two months), however, diminished sulfate reduction in reactor B somewhat. Arsenic removal in reactor A was impacted slightly by long-term use of AAB, but arsenic removals achieved by the entire system during NAB and AAB periods were not significantly different (p>0.05) and arsenic concentrations were reduced from approximately 200 μg/L to below 20 μg/L. These results indicate that AAB can be implemented in anaerobic nitrate and arsenic removal systems. PMID:22209197

  9. Simultaneous carbon and nitrogen removal in anoxic-aerobic circulating fluidized bed biological reactor (CFBBR).

    PubMed

    Cui, Y; Nakhla, G; Zhu, J; Patel, A

    2004-06-01

    Biological nutrient removal (BNR) in municipal wastewater treatment to remove carbonaceous substrates and nutrients, has recently become increasingly popular worldwide due to increasingly stringent regulations. Biological fluidized bed (BFB) technology, which could be potentially used for BNR, can provide some advantages such as high efficiency and a compact structure. This work shows the results of simultaneous elimination of organic carbon and nitrogen using a circulating fluidized bed biological reactor (CFBBR, which has been developed recently for chemical engineering processes. The CFBBR has two fluidized beds, running as anoxic and aerobic processes to accomplish simultaneous nitrification and denitrification, with continuous liquid recirculation through the anoxic bed and the aerobic bed. Soluble COD concentrations in the effluent ranging from 4 to 20 mg l(-1) were obtained at varying COD loading rates; ammonia nitrogen removal efficiencies averaged in excess of 99% at a minimum total hydraulic retention time (HRT) of 2.0 hours over a temperature range of 25 degrees C to 28 degrees C. Effluent nitrate nitrogen concentration of less than 5 mg l(-1) was achieved by increasing effluent recycle rate. No nitrite accumulation was observed either in the anoxic bed or in the aerobic bed. The system was able to treat grit chamber effluent wastewater at a HRT of 2.0 hours while achieving average effluent BOD, COD, NH3-N, TKN, nitrates, total phosphate, TSS and VSS concentrations of 10 mg l(-1), 18 mg l(-1), 1.3 mg l(-1), 1.5 mg l(-1), 7 mg l(-1), 2.0 mg l(-1), 10 mg l(-1) and 8 mg l(-1) respectively. The CFBBR appears to be not only an excellent alternative for conventional activated sludge type BNR technologies but also capable of processing much higher loadings that are suitable for industrial applications. PMID:15369290

  10. Interference of iron as a coagulant on MIB removal by powdered activated carbon adsorption for low turbidity waters.

    PubMed

    Seckler, Ferreira Filho Sidney; Margarida, Marchetto; Rosemeire, Alves Laganaro

    2013-08-01

    Powered activated carbon (PAC) is widely used in water treatment plants to minimize odors in drinking water. This study investigated the removal of 2-methylisoborneol (MIB) by PAC adsorption, combined with coagulation using iron as a coagulant. The adsorption and coagulation process were studied through different case scenarios of jar tests. The analysis evaluated the effect of PAC dosing in the liquid phase immediately before or after the coagulant addition. Ferric sulphate was used as the coagulant with dosages from 10 to 30 mg/L, and PAC dosages varied from 10 to 40 mg/L. The highest MIB removal efficiency (about 70%) was achieved without the coagulant addition and with the highest PAC dosage (40 mg/L). Lower MIB removal efficiencies were observed in the presence of coagulant, showing a clear interference of the iron precipitate or coagulant in the adsorption process. The degree of interference of the coagulation process in the MIB removal was proportional to the ratio of ferric hydroxide mass to the PAC mass. For both cases of PAC dosing, upstream and downstream of the coagulant injection point, the MIB removal efficiency was similar. However, MIB removal efficiency was 15% lower when compared with experiments without the coagulant application. This interference in the MIB adsorption occurs potentially because the coagulant coats the surface of the carbon and interferes with the MIB coming in contact with the carbon's surface and pores. This constraint requires an increase of the PAC dosage to provide the same efficiency observed without coagulation. PMID:24520695

  11. Screening of carbon-based sorbents for the removal of elemental mercury from simulated combustion flue gas

    SciTech Conne