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Sample records for activated carbons gac

  1. IN-SITU REGENERATION OF GRANULAR ACTIVATED CARBON (GAC) USING FENTON'S REAGENTS

    EPA Science Inventory

    Fenton-dependent regeneration of granular activated carbon (GAC) initially saturated with one of several chlorinated aliphatic contaminants was studied in batch and continuous-flow reactors. Homogeneous and heterogeneous experiments were designed to investigate the effects of va...

  2. Economical and ecological comparison of granular activated carbon (GAC) adsorber refill strategies.

    PubMed

    Bayer, Peter; Heuer, Edda; Karl, Ute; Finkel, Michael

    2005-05-01

    Technical constraints can leave a considerable freedom in the design of a technology, production or service strategy. Choosing between economical or ecological decision criteria then characteristically leads to controversial solutions of ideal systems. For the adaptation of granular-activated carbon (GAC) fixed beds, various technical factors determine the adsorber volume required to achieve a desired service life. In considering carbon replacement and recycling, a variety of refill strategies are available that differ in terms of refill interval, respective adsorber volume, and time-dependent use of virgin, as well as recycled GAC. Focusing on the treatment of contaminant groundwater, we compare cost-optimal reactor configurations and refill strategies to the ecologically best alternatives. Costs and consumption of GAC are quantified within a technical-economical framework. The emissions from GAC production out of hard coal, transport and recycling are equally derived through a life cycle impact assessment. It is shown how high discount rates lead to a preference of small fixed-bed volumes, and accordingly, a high number of refills. For fixed discount rates, the investigation reveals that both the economical as well as ecological assessment of refill strategies are especially sensitive to the relative valuation of virgin and recycled GAC. Since recycling results in economic and ecological benefits, optimized systems thus may differ only slightly.

  3. 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.

  4. Development of biomass in a drinking water granular active carbon (GAC) filter.

    PubMed

    Velten, Silvana; Boller, Markus; Köster, Oliver; Helbing, Jakob; Weilenmann, Hans-Ulrich; Hammes, Frederik

    2011-12-01

    Indigenous bacteria are essential for the performance of drinking water biofilters, yet this biological component remains poorly characterized. In the present study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the first six months of operation. GAC particles were sampled from four different depths (10, 45, 80 and 115 cm) and attached biomass was measured with adenosine tri-phosphate (ATP) analysis. The attached biomass accumulated rapidly on the GAC particles throughout all levels in the filter during the first 90 days of operation and maintained a steady state afterward. Vertical gradients of biomass density and growth rates were observed during start-up and also in steady state. During steady state, biomass concentrations ranged between 0.8-1.83 x 10(-6) g ATP/g GAC in the filter, and 22% of the influent dissolved organic carbon (DOC) was removed. Concomitant biomass production was about 1.8 × 10(12) cells/m(2)h, which represents a yield of 1.26 × 10(6) cells/μg. The bacteria assimilated only about 3% of the removed carbon as biomass. At one point during the operational period, a natural 5-fold increase in the influent phytoplankton concentration occurred. As a result, influent assimilable organic carbon concentrations increased and suspended bacteria in the filter effluent increased 3-fold as the direct consequence of increased growth in the biofilter. This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilters. PMID:21982281

  5. Development of biomass in a drinking water granular active carbon (GAC) filter.

    PubMed

    Velten, Silvana; Boller, Markus; Köster, Oliver; Helbing, Jakob; Weilenmann, Hans-Ulrich; Hammes, Frederik

    2011-12-01

    Indigenous bacteria are essential for the performance of drinking water biofilters, yet this biological component remains poorly characterized. In the present study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the first six months of operation. GAC particles were sampled from four different depths (10, 45, 80 and 115 cm) and attached biomass was measured with adenosine tri-phosphate (ATP) analysis. The attached biomass accumulated rapidly on the GAC particles throughout all levels in the filter during the first 90 days of operation and maintained a steady state afterward. Vertical gradients of biomass density and growth rates were observed during start-up and also in steady state. During steady state, biomass concentrations ranged between 0.8-1.83 x 10(-6) g ATP/g GAC in the filter, and 22% of the influent dissolved organic carbon (DOC) was removed. Concomitant biomass production was about 1.8 × 10(12) cells/m(2)h, which represents a yield of 1.26 × 10(6) cells/μg. The bacteria assimilated only about 3% of the removed carbon as biomass. At one point during the operational period, a natural 5-fold increase in the influent phytoplankton concentration occurred. As a result, influent assimilable organic carbon concentrations increased and suspended bacteria in the filter effluent increased 3-fold as the direct consequence of increased growth in the biofilter. This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilters.

  6. Biodegradation of high explosives on granular activated carbon [GAC]: Enhanced desorption of high explosives from GAC -- Batch studies

    SciTech Connect

    Morley, M.C.; Speitel, G.E. Jr.

    1999-03-01

    Adsorption to GAC is an effective method for removing high explosives (HE) compounds from water, but no permanent treatment is achieved. Bioregeneration, which treats adsorbed contaminants by desorption and biodegradation, is being developed as a method for reducing GAC usage rates and permanently degrading RDX and HMX. Because desorption is often the limiting mass transfer mechanism in bioregeneration systems, several methods for increasing the rate and extent of desorption of RDX and HMX are being studied. These include use of cosolvents (methanol and ethanol), surfactants (both anionic and nonionic), and {beta}- and {gamma}-cyclodextrins. Batch experiments to characterize the desorption of these HEs from GAC have been completed using Northwestern LB-830, the GAC being used at Pantex. Over a total of 11 days of desorption, about 3% of the adsorbed RDX was desorbed from the GAC using buffered water as the desorption fluid. In comparison, about 96% of the RDX was extracted from the GAC by acetonitrile over the same desorption period. Ethanol and methanol were both effective in desorbing RDX and HMX; higher alcohol concentrations were able to desorb more HE from the GAC. Surfactants varied widely in their abilities to enhance desorption of HEs. The most effective surfactant that was studied was sodium dodecyl sulfate (SDS), which desorbed 56.4% of the adsorbed RDX at a concentration of 500 mg SDS/L. The cyclodextrins that were used were marginally more effective than water. Continuous-flow column tests are underway for further testing the most promising of these methods. These results will be compared to column experiments that have been completed under baseline conditions (using buffered water as the desorption fluid). Results of this research will support modeling and design of further desorption and bioregeneration experiments.

  7. Removing 17β-estradiol from drinking water in a biologically active carbon (BAC) reactor modified from a granular activated carbon (GAC) reactor.

    PubMed

    Li, Zhongtian; Dvorak, Bruce; Li, Xu

    2012-06-01

    Estrogenic compounds in drinking water sources pose potential threats to human health. Treatment technologies are needed to effectively remove these compounds for the production of safe drinking water. In this study, GAC adsorption was first tested for its ability to remove a model estrogenic compound, 17β-estradiol (E2). Although GAC showed a relatively high adsorption capacity for E2 in isotherm experiments, it appeared to have a long mass transfer zone in a GAC column reactor, causing an early leakage of E2 in the effluent. With an influent E2 concentration of 20 μg/L, the GAC reactor was able to bring down effluent E2 to ≈ 200 ng/L. To further enhance E2 removal, the GAC reactor was converted to a biologically active carbon (BAC) reactor by promoting biofilm growth in the reactor. Under optimal operating conditions, the BAC reactor had an effluent E2 concentration of ≈ 50 ng/L. With the empty bed contact times tested, the reactor exhibited more robust E2 removal performance under the BAC operation than under the GAC operation. It is noted that estrone (E1), an E2 biodegradation intermediate, was frequently detected in reactor effluent during the BAC operation. Results from this study suggested that BAC could be an effective drinking water treatment process for E2 removal and in the meantime E1 accumulation needs to be addressed.

  8. Hydrophobic organic chemicals (HOCs) removal from biologically treated landfill leachate by powder-activated carbon (PAC), granular-activated carbon (GAC) and biomimetic fat cell (BFC).

    PubMed

    Liyan, Song; Youcai, Zhao; Weimin, Sun; Ziyang, Lou

    2009-04-30

    Biological pretreatment efficiently remove organic matter from landfill leachate, but further removal of refractory hydrophobic organic chemicals (HOCs) is hard even with advanced treatment. In this work, three-stage-aged refuse bioreactor (ARB) efficiently removed chemical oxygen demand (COD) and biochemical oxygen demand (BOD) of fresh leachate produced in Shanghai laogang landfill, from 8603 to 451 mg L(-1) and 1368 to 30 mg L(-1), respectively. In downstream treatment, 3 g L(-1) powder-activated carbon (PAC), granular-activated carbon (GAC) and biomimetic fat cell (BFC) removed 89.2, 73.4 and 81.1% HOCs, but only 24.6, 19.1 and 8.9% COD, respectively. Through the specific HOCs accumulation characteristics of BFC, about 11.2% HOCs with low molecular weight (<1000 Da) in the biologically treated leachate were concluded. Since HOCs are competitively trapped by dissolved organic matters (DOM), the ultimate removal of HOCs from leachate is unreachable by activated carbon or BFC. It was also found that the biologically treated leachate effluent exhibited a wide molecular weight distribution (34-514,646 Da). These constitutes are derived from both autochthonous and allochthonous matters as well as biological activities.

  9. Treatability studies with granular activated carbon (GAC) and sequencing batch reactor (SBR) system for textile wastewater containing direct dyes.

    PubMed

    Sirianuntapiboon, Suntud; Sansak, Jutarat

    2008-11-30

    The GAC-SBR efficiency was decreased with the increase of dyestuff concentration or the decrease of bio-sludge concentration. The system showed the highest removal efficiency with synthetic textile wastewater (STWW) containing 40 mg/L direct red 23 or direct blue 201 under MLSS of 3,000 mg/L and hydraulic retention time (HRT) of 7.5 days. But, the effluent NO(3)(-) was higher than that of the influent. Direct red 23 was more effective than direct blue 201 to repress the GAC-SBR system efficiency. The dyes removal efficiency of the system with STWW containing direct red 23 was reduced by 30% with the increase of direct red 23 from 40 mg/L to 160 mg/L. The system with raw textile wastewater (TWW) showed quite low BOD(5) TKN and dye removal efficiencies of only 64.7+/-4.9% and 50.2+/-6.9%, respectively. But its' efficiencies could be increased by adding carbon sources (BOD(5)). The dye removal efficiency with TWW was increased by 30% and 20% by adding glucose (TWW+glucose) or Thai rice noodle wastewater (TWW+TRNWW), respectively. SRT of the systems were 28+/-1 days and 31+/-2 days with TWW+glucose and TWW+TRNWW, respectively.

  10. Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

    PubMed

    Wu, Tiehang; Fu, George Yuzhu; Sabula, Michael; Brown, Tommy

    2014-12-01

    Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment.

  11. Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

    PubMed

    Wu, Tiehang; Fu, George Yuzhu; Sabula, Michael; Brown, Tommy

    2014-12-01

    Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment. PMID:25267475

  12. Successful treatment of high azo dye concentration wastewater using combined anaerobic/aerobic granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR): simultaneous adsorption and biodegradation processes.

    PubMed

    Hosseini Koupaie, E; Alavi Moghaddam, M R; Hashemi, S H

    2013-01-01

    The application of a granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR) for treatment of wastewater containing 1,000 mg/L Acid Red 18 (AR18) was investigated in this research. The treatment system consisted of a sequencing batch reactor equipped with moving GAC as biofilm support. Each treatment cycle consisted of two successive anaerobic (14 h) and aerobic (8 h) reaction phases. Removal of more than 91% chemical oxygen demand (COD) and 97% AR18 was achieved in this study. Investigation of dye decolorization kinetics showed that the dye removal was stimulated by the adsorption capacity of the GAC at the beginning of the anaerobic phase and then progressed following a first-order reaction. Based on COD analysis results, at least 77.8% of the dye total metabolites were mineralized during the applied treatment system. High-performance liquid chromatography analysis revealed that more than 97% of 1-naphthyalamine-4-sulfonate as one of the main sulfonated aromatic constituents of AR18 was removed during the aerobic reaction phase. According to the scanning electron microscopic analysis, the microbial biofilms grew in most cavities and pores of the GAC, but not on the external surfaces of the GAC.

  13. FENTON-DRIVEN CHEMICAL REGENERATION OF MTBE-SPENT GAC

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was chemically regenerated utilizing the Fenton mechanism. Two successive GAC regeneration cycles were performed involving iterative adsorption and oxidation processes: MTBE was adsorbed to the GAC, oxidized, r...

  14. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  15. Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon

    EPA Science Inventory

    Fenton- or persulfate-driven chemical oxidation regeneration of spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto GAC and chemical oxidation regeneration of the spent-GAC. Environmental...

  16. Application of response surface methodology (RSM) for optimisation of COD, NH3-N and 2,4-DCP removal from recycled paper wastewater in a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR).

    PubMed

    Muhamad, Mohd Hafizuddin; Sheikh Abdullah, Siti Rozaimah; Mohamad, Abu Bakar; Abdul Rahman, Rakmi; Hasan Kadhum, Abdul Amir

    2013-05-30

    In this study, the potential of a pilot-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR) for removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and 2,4-dichlorophenol (2,4-DCP) from recycled paper wastewater was assessed. For this purpose, the response surface methodology (RSM) was employed, using a central composite face-centred design (CCFD), to optimise three of the most important operating variables, i.e., hydraulic retention time (HRT), aeration rate (AR) and influent feed concentration (IFC), in the pilot-scale GAC-SBBR process for recycled paper wastewater treatment. Quadratic models were developed for the response variables, i.e., COD, NH3-N and 2,4-DCP removal, based on the high value (>0.9) of the coefficient of determination (R(2)) obtained from the analysis of variance (ANOVA). The optimal conditions were established at 750 mg COD/L IFC, 3.2 m(3)/min AR and 1 day HRT, corresponding to predicted COD, NH3-N and 2,4-DCP removal percentages of 94.8, 100 and 80.9%, respectively.

  17. Performance of air stripping and GAC (granular activated carbon) for SOC (synthetic organic chemical) and VOC (volatile organic chemical) removal from ground water. Final report, October 1983-November 1987

    SciTech Connect

    Hand, D.W.; Crittenden, J.C.; Miller, J.M.; Gehin, J.L.

    1988-09-01

    This study compares the ability and cost-effectiveness of granular activated carbon and packed-tower aeration (air stripping) in removing synthetic organic and volatile organic chemicals (SOCs and VOCs) from a contaminated groundwater source in Wausau, WI. Among the SOCs and VOCs identified and targeted for removal were cis-1,2-dichloroethene, trichloroethene, tetrachlorethene, and toluene. A liquid-phase GAC pilot-plant, full-scale GAS adsorber, and a full-scale air-stripping tower were designed, built, and operated to provide data so that the process performance could be evaluated. Extensive laboratory studies were performed. Mathematical models and correlations for obtaining kinetic parameters and single-solute isotherm parameters were developed and tested by comparing their results to those obtained from the pilot plant. Possible surrogate parameters were investigated. Cost estimates are compared.

  18. REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

  19. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    EPA Science Inventory

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  20. Some properties of a granular activated carbon-sequencing batch reactor (GAC-SBR) system for treatment of textile wastewater containing direct dyes.

    PubMed

    Sirianuntapiboon, Suntud; Sadahiro, Ohmomo; Salee, Paneeta

    2007-10-01

    Resting (living) bio-sludge from a domestic wastewater treatment plant was used as an adsorbent of both direct dyes and organic matter in a sequencing batch reactor (SBR) system. The dye adsorption capacity of the bio-sludge was not increased by acclimatization with direct dyes. The adsorption of Direct Red 23 and Direct Blue 201 onto the bio-sludge was almost the same. The resting bio-sludge showed higher adsorption capacity than the autoclaved bio-sludge. The resting bio-sludge that was acclimatized with synthetic textile wastewater (STWW) without direct dyes showed the highest Direct Blue 201, COD, and BOD(5) removal capacities of 16.1+/-0.4, 453+/-7, and 293+/-9 mg/g of bio-sludge, respectively. After reuse, the dye adsorption ability of deteriorated bio-sludge was recovered by washing with 0.1% sodium dodecyl sulfate (SDS) solution. The direct dyes in the STWW were also easily removed by a GAC-SBR system. The dye removal efficiencies were higher than 80%, even when the system was operated under a high organic loading of 0.36kgBOD(5)/m(3)-d. The GAC-SBR system, however, showed a low direct dye removal efficiency of only 57+/-2.1% with raw textile wastewater (TWW) even though the system was operated with an organic loading of only 0.083kgBOD(5)/m(3)-d. The dyes, COD, BOD(5), and total kjeldalh nitrogen removal efficiencies increased up to 76.0+/-2.8%, 86.2+/-0.5%, 84.2+/-0.7%, and 68.2+/-2.1%, respectively, when 0.89 g/L glucose (organic loading of 0.17kgBOD(5)/m(3)-d) was supplemented into the TWW.

  1. Particle Size Effects on Fenton Regeneration of MTBE-spent Activated Carbon

    EPA Science Inventory

    Fenton-driven regeneration of spent granular activated carbon (GAC) is a developing technology that may reduce water treatment costs. In this study, the effect of GAC particle size on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was evaluated. The GAC was...

  2. Effect of ozone and granular activated coal (GAC) on the bioactivity of drinking water.

    PubMed

    Sallanko, Jarmo; Iivari, Pekka; Heiska, Eeva

    2009-02-15

    In this research, the appearance of easily biodegradable organic material in ozonation and granular activated coal (GAC) filtration was studied. The amount of bioactivity was measured by conventional AOC analyses used in two different modes and also using quite a new growth potential (GP) method. GAC filtration without ozone doubled the amount of AOC of the chemically treated surface water, whereas by ozonation with GAC filtration it was possible to halve the amount of the AOC. The measurement of GP was noticeably simpler than measuring AOC, but for wider use more parallel studies are needed for the comparability of the results of the analysis. PMID:19132584

  3. Effect of ozone and granular activated coal (GAC) on the bioactivity of drinking water

    SciTech Connect

    Sallanko, J.; Iivari, P.; Heiska, E.

    2009-07-01

    In this research, the appearance of easily biodegradable organic material in ozonation and granular activated coal (GAC) filtration was studied. The amount of bioactivity was measured by conventional AOC analyses used in two different modes and also using quite a new growth potential (GP) method. GAC filtration without ozone doubled the amount of AOC of the chemically treated surface water, whereas by ozonation with GAC filtration it was possible to halve the amount of the AOC. The measurement of GP was noticeably simpler than measuring AOC, but for wider use more parallel studies are needed for the comparability of the results of the analysis.

  4. Gac-mediated changes in pyrroloquinoline quinone biosynthesis enhance the antimicrobial activity of Pseudomonas fluorescens SBW25.

    PubMed

    Cheng, Xu; van der Voort, Menno; Raaijmakers, Jos M

    2015-02-01

    In Pseudomonas species, production of secondary metabolites and exoenzymes is regulated by the GacS/GacA two-component regulatory system. In Pseudomonas fluorescens SBW25, mutations in the Gac-system cause major transcriptional changes and abolished production of the lipopeptide viscosin and of an exoprotease. In contrast to many other Pseudomonas species and strains, inactivation of the Gac-system in strain SBW25 significantly enhanced its antimicrobial activities against oomycete, fungal and bacterial pathogens. Here, random plasposon mutagenesis of the gacS mutant led to the identification of seven mutants with reduced or loss of antimicrobial activity. In four mutants, the plasposon insertion was located in genes of the pyrroloquinoline quinone (PQQ) biosynthesis pathway. Genetic complementation, ectopic expression, activity bioassays and Reversed-phase high-performance liquid chromatography (RP-HPLC) analyses revealed that a gacS mutation in SBW25 leads to enhanced expression of pqq genes, resulting in an increase in gluconic and 2-ketogluconic acid production, which in turn acidified the extracellular medium to levels that inhibit growth of other microorganisms. We also showed that PQQ-mediated acidification comes with a growth penalty for the gacS mutant in the stationary phase. In conclusion, PQQ-mediated acidification compensates for the loss of several antimicrobial traits in P. fluorescens SBW25 and may help gac mutants to withstand competitors.

  5. Fenton-driven regeneration of MTBE-spent granular activated carbon - Effects of particle size and Iron Amendment Procedures

    EPA Science Inventory

    Fenton-driven regeneration of spent granular activated carbon (GAC) is a technology being developed to regenerate organic contaminant-spent GAC. Here, the effect of GAC particle size (>2 mm to <0.35 mm) on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was ev...

  6. IN-PLACE REGENERATION OF GAC USING FENTON'S REAGENTS

    EPA Science Inventory

    This paper evaluates the feasibility of using Fenton’s reagents for in-place recovery of spent granular activated carbon (GAC). Fenton’s reagents are cycled through spent GAC to degrade sorbed chlorinated hydrocarbons with little loss of carbon capacity. Seven chlorinated compou...

  7. PtrA Is Functionally Intertwined with GacS in Regulating the Biocontrol Activity of Pseudomonas chlororaphis PA23

    PubMed Central

    Shah, Nidhi; Klaponski, Natasha; Selin, Carrie; Rudney, Rachel; Fernando, W. G. Dilantha; Belmonte, Mark F.; de Kievit, Teresa R.

    2016-01-01

    In vitro inhibition of the fungal pathogen Sclerotinia sclerotiorum by Pseudomonas chlororaphis PA23 is reliant upon a LysR-type transcriptional regulator (LTTR) called PtrA. In the current study, we show that Sclerotinia stem rot and leaf infection are significantly increased in canola plants inoculated with the ptrA-mutant compared to the wild type, establishing PtrA as an essential regulator of PA23 biocontrol. LTTRs typically regulate targets that are upstream of and divergently transcribed from the LTTR locus. We identified a short chain dehydrogenase (scd) gene immediately upstream of ptrA. Characterization of a scd mutant revealed that it is phenotypically identical to the wild type. Moreover, scd transcript abundance was unchanged in the ptrA mutant. These findings indicate that PtrA regulation does not involve scd, rather this LTTR controls genes located elsewhere on the chromosome. Employing a combination of complementation and transcriptional analysis we investigated whether connections exist between PtrA and other regulators of biocontrol. Besides ptrA, gacS was the only gene able to partially rescue the wild-type phenotype, establishing a connection between PtrA and the sensor kinase GacS. Transcriptomic analysis revealed decreased expression of biosynthetic (phzA, prnA) and regulatory genes (phzI, phzR, rpoS, gacA, rsmX, rsmZ, retS) in the ptrA mutant; conversely, rsmE, and rsmY were markedly upregulated. The transcript abundance of ptrA was nine-fold higher in the mutant background indicating that this LTTR negatively autoregulates itself. In summary, PtrA is an essential regulator of genes required for PA23 biocontrol that is functionally intertwined with GacS. PMID:27713742

  8. EFFECT OF GAC CHARACTERISTICS ON ADSORPTION OF ORGANIC POLLUTANTS

    EPA Science Inventory

    The impact of the characteristics of granular activated carbon (GAC) on adsorption capacity and on the potential for polymerization of phenolic compounds on the surface of GAC in the presence of molecular oxygen is evaluated in this study. Adsorption isotherm data were collected...

  9. Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

    EPA Science Inventory

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

  10. Catalytic Sorption of (Chloro)Benzene and Napthalene in Aqueous Solutions by Granular Activated Carbon Supported Bimetallic Iron and Palladium Nanoparticles

    EPA Science Inventory

    Adsorption of benzene, chlorobenzene, and naphthalene on commercially available granular activated carbon (GAC) and bimetallic nanoparticle (Fe/Pd) loaded GAC was investigated for the potential use in active capping of contaminated sediments. Freundlich and Langmuir linearizatio...

  11. USING ISOTHERMS TO PREDICT GAC'S CAPACITY FOR SYNTHETIC ORGANICS

    EPA Science Inventory

    This investigation involved operating a pilot granular activated carbon (GAC) plant to obtain capacity data under typical field conditions, determining isotherms for selected synthetic organic chemicals, and comparing the capacity predicted by the isotherm data with the pilot-pla...

  12. EVALUATION OF THE MIDDAS SYSTEM FOR DESIGNING GAC ADSORBERS

    EPA Science Inventory

    The Micro-Diameter-Depth Adsorption System (MIDDAS) was evaluated for its usefulness in determining equilibrium parameters for adsorption in granular activated carbon (GAC) systems. The system employs a column configuration for determining such parameters, rather than the traditi...

  13. Fenton-driven chemical regeneration of MTBE-spent GAC.

    PubMed

    Huling, Scott G; Jones, Patrick K; Ela, Wendell P; Arnold, Robert G

    2005-05-01

    Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was chemically regenerated utilizing the Fenton mechanism. Two successive GAC regeneration cycles were performed involving iterative adsorption and oxidation processes: MTBE was adsorbed to the GAC, oxidized, re-adsorbed, oxidized, and finally re-adsorbed. Oxidant solutions comprised of hydrogen peroxide (H2O2) (1.7-2.0%) and FeSO4 x 7H2O (3 g/L) (pH 2.5), were recirculated through the GAC column (30% bed expansion). The regeneration efficiency after two full cycles of treatment was calculated to be 91%. The cost of H2O2 was 0.59 dollars/kg GAC (0.27 dollars/lb) per regeneration cycle. There was no loss of sorptive capacity. Small reductions in carbon surface area and pore volume were measured. The lack of carbon deterioration under aggressive oxidative conditions was attributed to the oxidation of the target contaminants relative to the oxidation of carbon surfaces. The reaction byproducts from MTBE oxidation, tertiary butanol and acetone, were also degraded and did not accumulate significantly on the GAC. Excessive accumulation of Fe on the GAC and consequent interference with MTBE sorption and carbon regeneration was controlled by monitoring and adjusting Fe in the oxidative solution.

  14. ppGpp controlled by the Gac/Rsm regulatory pathway sustains biocontrol activity in Pseudomonas fluorescens CHA0.

    PubMed

    Takeuchi, Kasumi; Yamada, Kosumi; Haas, Dieter

    2012-11-01

    In Pseudomonas fluorescens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway is instrumental for secondary metabolism and biocontrol of root pathogens via the expression of regulatory small RNAs (sRNAs). Furthermore, in strain CHA0, an imbalance in the Krebs cycle can affect the strain's ability to produce extracellular secondary metabolites, including biocontrol factors. Here, we report the metabolome of wild-type CHA0, a gacA-negative mutant, which has lost Gac/Rsm activities, and a retS-negative mutant, which shows strongly enhanced Gac/Rsm-dependent activities. Capillary electrophoresis-based metabolomic profiling revealed that the gacA and retS mutations had opposite effects on the intracellular levels of a number of central metabolites, suggesting that the Gac/Rsm pathway regulates not only secondary metabolism but also primary metabolism in strain CHA0. Among the regulated metabolites identified, the alarmone guanosine tetraphosphate (ppGpp) was characterized in detail by the construction of relA (for ppGpp synthase) and spoT (for ppGpp synthase/hydrolase) deletion mutants. In a relA spoT double mutant, ppGpp synthesis was completely abolished, the expression of Rsm sRNAs was attenuated, and physiological functions such as antibiotic production, root colonization, and plant protection were markedly diminished. Thus, ppGpp appears to be essential for sustaining epiphytic fitness and biocontrol activity of strain CHA0.

  15. Effects on temperature and acidic pre-treatment on Fenton-driven oxidation of MTBE-spent granular activated carbon

    EPA Science Inventory

    Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the p...

  16. Effects of Temperature and Acidic Pre-Treatment on Fenton-Driven Oxidation of MTBE-Spent Granular Activated Carbon

    EPA Science Inventory

    Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the pH ...

  17. GacA-controlled activation of promoters for small RNA genes in Pseudomonas fluorescens.

    PubMed

    Humair, Bérénice; Wackwitz, Birgit; Haas, Dieter

    2010-03-01

    The Gac/Rsm signal transduction pathway positively regulates secondary metabolism, production of extracellular enzymes, and biocontrol properties of Pseudomonas fluorescens CHA0 via the expression of three noncoding small RNAs, termed RsmX, RsmY, and RsmZ. The architecture and function of the rsmY and rsmZ promoters were studied in vivo. A conserved palindromic upstream activating sequence (UAS) was found to be necessary but not sufficient for rsmY and rsmZ expression and for activation by the response regulator GacA. A poorly conserved linker region located between the UAS and the -10 promoter sequence was also essential for GacA-dependent rsmY and rsmZ expression, suggesting a need for auxiliary transcription factors. One such factor involved in the activation of the rsmZ promoter was identified as the PsrA protein, previously recognized as an activator of the rpoS gene and a repressor of fatty acid degradation. Furthermore, the integration host factor (IHF) protein was found to bind with high affinity to the rsmZ promoter region in vitro, suggesting that DNA bending contributes to the regulated expression of rsmZ. In an rsmXYZ triple mutant, the expression of rsmY and rsmZ was elevated above that found in the wild type. This negative feedback loop appears to involve the translational regulators RsmA and RsmE, whose activity is antagonized by RsmXYZ, and several hypothetical DNA-binding proteins. This highly complex network controls the expression of the three small RNAs in response to cell physiology and cell population densities.

  18. Determining activated carbon performance

    SciTech Connect

    Naylor, W.F.; Rester, D.O.

    1995-07-01

    This article discusses the key elements involved in evaluating a system`s performance. Empty bed contact time (EBCT) is a term used to describe the length of time a liquid stream being treated is in contact with a granular activated carbon bed. The EBCT is the time required for a fluid to pass through the volume equivalent of the media bed, without the media being present. In a bed of granular activated carbon, the void volume or space between particles is usually about 45 percent. Therefore, the EBCT is about twice the true or actual time of contact between the fluid being treated and the GAC particles. The EBCT plays an important role in determining the effectiveness and longevity of granular activated carbon (GAC) used to treat liquids in a fixed-bed adsorber. Factors that influence and are influenced by EBCT, and their relationship to GAC performance in a treatment scheme include: adsorption, mass transfer zone, impurity concentration, adsorption affinity, flow rate and system design considerations.

  19. FENTON-DRIVEN REGENERATION OF GRANULAR ACTIVATED CARBON: A TECHNOLOGY OVERVIEW

    EPA Science Inventory

    A Fenton-driven mechanism for regenerating spent granular activated carbon (GAC) involves the combined, synergistic use of two reliable and well established treatment technologies - adsorption onto activated carbon and Fenton oxidation. During carbon adsorption treatment, enviro...

  20. Degradation of 3,3'-iminobis-propanenitrile in aqueous solution by Fe(0)/GAC micro-electrolysis system.

    PubMed

    Lai, Bo; Zhou, Yuexi; Yang, Ping; Yang, Jinghui; Wang, Juling

    2013-01-01

    The degradation of 3,3'-iminobis-propanenitrile was investigated using the Fe(0)/GAC micro-electrolysis system. Effects of influent pH value, Fe(0)/GAC ratio and granular activated carbon (GAC) adsorption on the removal efficiency of the pollutant were studied in the Fe(0)/GAC micro-electrolysis system. The degradation of 3,3'-iminobis-propanenitrile was affected by influent pH, and a decrease of the influent pH values from 8.0 to 4.0 led to the increase of degradation efficiency. Granular activated carbon was added as cathode to form macroscopic galvanic cells between Fe(0) and GAC and enhance the current efficiency of the Fe(0)/GAC micro-electrolysis system. The GAC could only adsorb the pollutant and provide buffer capacity for the Fe(0)/GAC micro-electrolysis system, and the macroscopic galvanic cells of the Fe(0)/GAC micro-electrolysis system played a leading role in degradation of 3,3'-iminobis-propanenitrile. With the analysis of the degradation products with GC-MS, possible reaction pathway for the degradation of 3,3'-iminobis-propanenitrile by the Fe(0)/GAC micro-electrolysis system was suggested.

  1. Removal of bromate and assimilable organic carbon from drinking water using granular activated carbon.

    PubMed

    Huang, W J; Peng, H S; Peng, M Y; Chen, L Y

    2004-01-01

    This study investigated the feasibility of using granular activated carbon (GAC) to remove bromate ion (BrO3-) and assimilable organic carbon (AOC) from drinking water through a rapid small-scale column test (RSSCT) method and a pilot-scale study. Results from RSSCT indicated that the GAC capacity for BrO3- removal was dependent on the GAC type, empty bed contact time (EBCT), and source water quality. The GAC with a high number of basic groups and higher pHpzc values showed an increased BrO3- removal capacity. BrO3- removal was improved by increasing EBCT. The high EBCT provides a greater opportunity for BrO3- to be adsorbed and reduced to Br- on the GAC surface. On the other hand, the presence of dissolved organic carbon (DOC) and anions, such as chloride, bromide, and sulfate, resulted in poor BrO3- reduction. In the GAC pilot plant, a GAC column preloaded for 12 months achieved a BrO3- and AOC removal range from 79-96% and 41-75%, respectively. The BrO3- amount removed was found to be proportional to the influent BrO3- concentration. However, the BrO3- removal rate apparently decreased with increasing operation time. In contrast, the AOC apparently increased during the long-term operation period. This may be a result of the contribution due to new GAC being gradually transformed into biological activated carbon (BAC), and the bacterial biomass adsorbed on GAC surface hindering BrO3- reduction by GAC either by blocking pores or adsorbing at the activated sites for BrO3- reduction. PMID:15566189

  2. EFFECT OF DISSOLVED OXYGEN ON PHENOLS BREAKTHROUGH FROM GAC ADSORBERS

    EPA Science Inventory

    This study demonstrates that molecular oxygen plays an important role in the adsorption of organic compounds from water by activated carbon. It was determined that the adsorptive capacity of granular activated carbon (GAC) for o-cresol can increase by almost 200% as a result of...

  3. Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

    PubMed

    Deng, Baolin; Kim, Eun-Sik

    2016-05-01

    Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC. The untreated GAC showed a low adsorption capacity for As(V). Adsorption of TCE by the NaClO/Fe-GAC was maximized, with an increased Freundlich constant. Removal of TCE in the binary-component system was decreased 15% by the untreated GAC, and NaClO- and NaClO/Fe-GAC showed similar efficiency to the single-component system because of the different chemical status of the GAC surfaces. Results of the adsorption isotherms of As(V) in the binary-component system were similar to adsorption isotherms of the single-component system. The adsorption affinities of single- and binary-component systems corresponded with electron transfer, competitive adsorption, and physicochemical properties.

  4. Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

    PubMed

    Deng, Baolin; Kim, Eun-Sik

    2016-05-01

    Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC. The untreated GAC showed a low adsorption capacity for As(V). Adsorption of TCE by the NaClO/Fe-GAC was maximized, with an increased Freundlich constant. Removal of TCE in the binary-component system was decreased 15% by the untreated GAC, and NaClO- and NaClO/Fe-GAC showed similar efficiency to the single-component system because of the different chemical status of the GAC surfaces. Results of the adsorption isotherms of As(V) in the binary-component system were similar to adsorption isotherms of the single-component system. The adsorption affinities of single- and binary-component systems corresponded with electron transfer, competitive adsorption, and physicochemical properties. PMID:27131303

  5. Treatment of semivolatile compounds in high strength wastes using an anaerobic expanded-bed GAC reactor

    EPA Science Inventory

    The potential of the anaerobic, expanded bed granular activated carbon (GAC) reactor in treating a high strength waste containing RCRA semivolatile organic compounds (VOCs) was studied. Six semivolatiles, orthochlorophenol, nitrobenzene, naphthalene, para-nitrophenol, lindane, a...

  6. IN-PLACE REGENERATION OF SVE LOADED GAC USING FENTON'S REAGENTS

    EPA Science Inventory

    Ten out of the 25 most frequently detected groundwater contaminants at hazardous waste sites are chlorinated volatile organic compounds (VOCs) 1. Trichloroethylene (TCE) and tetrachloroethylene (PCE) are among the top three 1. Granular activated carbon (GAC) adsorption is widel...

  7. IN-PLACE REGENERATION OF SVE LOADED GAC USING FENTON'S REAGENTS

    EPA Science Inventory

    Ten out of the 25 most frequently detected groundwater contaminants at hazardous waste sites are chlorinated volatile organic compounds (VOCs) 1 . Trichloroethylene (TCE) and tetrachloroethylene (PCE) are among the top three 1 . Granular activated carbon (GAC) adsorption is w...

  8. Persulfate Oxidation Regeneration of Granular Activated Carbon: Reversible Impacts on Sorption Behavior

    EPA Science Inventory

    Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH < 2) and the accumulation ...

  9. Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers

    SciTech Connect

    Lin, S.H.; Hsu, F.M.

    1995-06-01

    Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

  10. Comparison of toluene adsorption among granular activated carbon and different types of activated carbon fibers (ACFs).

    PubMed

    Balanay, Jo Anne G; Crawford, Shaun A; Lungu, Claudiu T

    2011-10-01

    Activated carbon fiber (ACF) has been demonstrated to be a good adsorbent for the removal of organic vapors in air. Some ACF has a comparable or larger surface area and higher adsorption capacity when compared with granular activated carbon (GAC) commonly used in respiratory protection devices. ACF is an attractive alternative adsorbent to GAC because of its ease of handling, light weight, and decreasing cost. ACF may offer the potential for short-term respiratory protection for first responders and emergency personnel. This study compares the critical bed depths and adsorption capacities for toluene among GAC and ACF of different forms and surface areas. GAC and ACF in cloth (ACFC) and felt (ACFF) forms were challenged in stainless steel chambers with a constant concentration of 500 ppm toluene via conditioned air at 25°C, 50% RH, and constant airflow (7 L/min). Breakthrough data were obtained for each adsorbent using gas chromatography with flame ionization detector. Surface areas of each adsorbent were determined using a physisorption analyzer. Results showed that the critical bed depth of GAC is 275% higher than the average of ACFC but is 55% lower than the average of ACFF. Adsorption capacity of GAC (with a nominal surface area of 1800 m(2)/g) at 50% breakthrough is 25% higher than the average of ACF with surface area of 1000 m(2)/g, while the rest of ACF with surface area of 1500 m(2)/g and higher have 40% higher adsorption capacities than GAC. ACFC with higher surface area has the smallest critical bed depth and highest adsorption capacity, which makes it a good adsorbent for thinner and lighter respirators. We concluded that ACF has great potential for application in respiratory protection considering its higher adsorption capacity and lower critical bed depth in addition to its advantages over GAC, particularly for ACF with higher surface area.

  11. IRON OPTIMIZATION FOR FENTON-DRIVEN OXIDATION OF MTBE-SPENT GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton-driven chemical regeneration of granular activated carbon (GAC) is accomplished through the addition of H2O2 and iron (Fe) to spent GAC. The overall objective of this treatment process is to transform target contaminants into less toxic byproducts, re-establish the sorpti...

  12. COST ANALYSIS OF ACTIVATED CARBON VERSUS PHOTOCATALYTIC OXIDATION FOR REMOVING ORGANIC COMPOUNDS FROM INDOOR AIR

    EPA Science Inventory

    A cost comparison has been conducted of 1 m3/s indoor air cleaners using granular activated carbon (GAC) vs. photocatalytic oxidation (PCO) for treating a steady-state inlet volatile organic compound (VOC) concentration of 0.3 mg/m3. The commercial GAC unit was costed assuming t...

  13. In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst

    EPA Science Inventory

    Granular activated carbon (GAC) can remove trace organic pollutants and natural organic matter (NOM) from industrial and municipal waters. This paper evaluates an iron nanocatalyst approach, based on Fenton-like oxidation reactions, to regenerate spent GAC within a packed bed con...

  14. Reduction of bromate by granular activated carbon

    SciTech Connect

    Kirisits, M.J.; Snoeyink, V.L.; Kruithof, J.C.

    1998-07-01

    Ozonation of waters containing bromide can lead to the formation of bromate, a probable human carcinogen. Since bromate will be regulated at 10 {micro}g/L by the Stage 1 Disinfectants/Disinfection By-Products Rule, there is considerable interest in finding a suitable method of bromate reduction. Granular activated carbon (GAC) can be used to chemically reduce bromate to bromide, but interference from organic matter and anions present in natural water render this process inefficient. In an effort to improve bromate reduction by GAC, several modifications were made to the GAC filtration process. The use of a biologically active carbon (BAC) filter ahead of a fresh GAC filter with and without preozonation, to remove the biodegradable organic matter, did not substantially improve the bromate removal of the GAC filter. The use of the BAC filter for biological bromate reduction proved to be the most encouraging experiment. By lowering the dissolved oxygen in the influent to the BAC from 8.0 mg/L to 2.0 mg/L, the percent bromate removal increased from 42% to 61%.

  15. Immobilized acclimated biomass-powdered activated carbon for the bioregeneration of granular activated carbon loaded with phenol and o-cresol.

    PubMed

    Toh, Run-Hong; Lim, Poh-Eng; Seng, Chye-Eng; Adnan, Rohana

    2013-09-01

    The objectives of the study are to use immobilized acclimated biomass and immobilized biomass-powdered activated carbon (PAC) as a novel approach in the bioregeneration of granular activated carbon (GAC) loaded with phenol and o-cresol, respectively, and to compare the efficiency and rate of the bioregeneration of the phenolic compound-loaded GAC using immobilized and suspended biomasses under varying GAC dosages. Bioregeneration of GAC loaded with phenol and o-cresol, respectively, was conducted in batch system using the sequential adsorption and biodegradation approach. The results showed that the bioregeneration efficiency of GAC loaded with phenol or o-cresol was basically the same irrespective of whether the immobilized or suspended biomass was used. Nonetheless, the duration for bioregeneration was longer under immobilized biomass. The beneficial effect of immobilized PAC-biomass for bioregeneration is the enhancement of the removal rate of the phenolic compounds via adsorption and the shortening of the bioregeneration duration. PMID:23796608

  16. UV-activated persulfate oxidation and regeneration of NOM-Saturated granular activated carbon.

    PubMed

    An, Dong; Westerhoff, Paul; Zheng, Mengxin; Wu, Mengyuan; Yang, Yu; Chiu, Chao-An

    2015-04-15

    A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 10(4) mJ/cm(2). The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC. PMID:25697692

  17. UV-activated persulfate oxidation and regeneration of NOM-Saturated granular activated carbon.

    PubMed

    An, Dong; Westerhoff, Paul; Zheng, Mengxin; Wu, Mengyuan; Yang, Yu; Chiu, Chao-An

    2015-04-15

    A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 10(4) mJ/cm(2). The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC.

  18. CONTROLLING ORGANICS WITH GAC: A COST AND PERFORMANCE ANALYSIS

    EPA Science Inventory

    The amendments to the US Safe Drinking Water Act require extensive evaluation of the feasibility or removing organic compounds using granular activated carbon (GAC). To meet deadlines for this technology evaluation, the US Environmental Prtotection Agency has combined the use of ...

  19. Adsorption And Simultaneous Dechlorination Of PCBs On GAC/Fe/Pd: Mechanistic Aspects And Reactive Capping Barrier Concept

    EPA Science Inventory

    There are many concerns and challenges in current remediation strategies for sediments contaminated with polychlorinated biphenyls (PCBs). Our efforts have been geared toward the development of granular activated carbon (GAC) impregnated with reactive iron/palladium (Fe/Pd) bime...

  20. Treatment of naphthalene-2-sulfonic acid from tannery wastewater by a granular activated carbon fixed bed inoculated with bacterial isolates Arthrobacter globiformis and Comamonas testosteroni.

    PubMed

    Song, Zhi; Edwards, Suzanne R; Burns, Richard G

    2006-02-01

    The kinetics of naphthalene-2-sulfonic acid (2-NSA) adsorption by granular activated carbon (GAC) were measured and the relationships between adsorption, desorption, bioavailability and biodegradation assessed. The conventional Langmuir model fitted the experimental sorption isotherm data and introduced 2-NSA degrading bacteria, established on the surface of the GAC, did not interfere with adsorption. The potential value of GAC as a microbial support in the aerobic degradation of 2-NSA by Arthrobacter globiformis and Comamonas testosteroni was investigated. Using both virgin and microbially colonised GAC, adsorption removed 2-NSA from the liquid phase up to its saturation capacity of 140 mg/g GAC within 48 h. However, between 83.2% and 93.3% of the adsorbed 2-NSA was bioavailable to both bacterial species as a source of carbon for growth. In comparison to the non-inoculated GAC, the combination of rapid adsorption and biodegradation increased the amount (by 70-93%) of 2-NSA removal from the influent phase as well as the bed-life of the GAC (from 40 to >120 d). A microbially conditioned GAC fixed-bed reactor containing 15 g GAC removed 100% 2-NSA (100 mg/l) from tannery wastewater at an empty bed contact time of 22 min for a minimum of 120 d without the need for GAC reconditioning or replacement. This suggests that small volume GAC bioreactors could be used for tannery wastewater recycling.

  1. Regeneration of granular activated carbon with adsorbed trichloroethylene using wet peroxide oxidation.

    PubMed

    Okawa, Kiyokazu; Suzuki, Kazuyoshi; Takeshita, Toshihiro; Nakano, Katsuyuki

    2007-03-01

    The objective of this study is to clarify the regeneration of granular activated carbon (GAC) adsorbed trichloroethylene (TCE) using wet peroxide oxidation (WPO). TCE and TOC concentrations decreased during WPO, whereas Cl(-) accumulated in water indicating that TCE was not only decomposed but was also mineralized to Cl(-) and CO(2) using WPO. Regeneration efficiencies (q/q(0)) of GAC regenerated at 150, 165 and 180 degrees C (initial pH 4) were 0.36, 0.45, 0.48, respectively. In addition, regeneration efficiencies of GAC regenerated in the solution of various initial pH (2.5, 3.0, 4.0) at 180 degrees C were 0.71, 0.60, 0.48, respectively. These results suggest that regeneration of GAC is more effective at higher reaction temperature and lower initial pH of the solution. In the repeated regeneration of GAC, the adsorption capacity of GAC for TCE gradually decreased and regeneration efficiency of the regenerated GAC at sixth step was 0.40. The adsorption capacity loss of regenerated GAC is probably due to oxidation of GAC during WPO. PMID:17224174

  2. Granular activated carbon/pyrite composites for environmental application: synthesis and characterization.

    PubMed

    Liang, Chenju; Lee, Po-Han

    2012-09-15

    The goal of this study was to produce a reactive granular activated carbon (GAC) coated with pyrite (FeS(2)) for environmental remediation, which would combine both functions of GAC adsorption and FeS(2) reduction reactions. GAC-FeS(2) composite materials have been successfully prepared via sequential processes, i.e., incipient wetness iron impregnation, transformation into hematite (Fe(2)O(3)) by calcination at 300 °C and sulfurization by calcination at 400 °C. The point of zero charge (pH(PZC)) of GAC washed with nitric acid (HNO(3)) decreased to improve the drawing of iron ionic species into the pores of GAC and the results of FTIR confirmed the predominance of carboxylic acid groups which cause a negative charged GAC surface. XRD results indicated that the calcined composites are transitional GAC-Fe(2)O(3) and final GAC-FeS(2). The obtained FeS(2) crystallite size calculated using Scherrer formulae was around 31-34 nm and SEM/SEI showed FeS(2) had an angular shape. The existence of FeS(2) in GAC gave rise to a significant reduction of BET surface and pore volume. However, even though these reductions may result in the decrease of adsorption capacity when compared to the virgin GAC, the coated reactive FeS(2) may result in the abiotic transformation of adsorbates such as trichloroethylene (TCE) and this would compensate for the loss of adsorption. Furthermore, the preliminary results of TCE experiments on GAC-FeS(2) adsorption/dechlorination revealed that the composite initially accumulated and confined TCE on GAC and gradually dechlorinated TCE by embedded FeS(2). PMID:22795588

  3. Evaluation of competitive adsorption in anaerobic GAC reactors

    SciTech Connect

    Nakhla, G.F.; Suidan, M.T.

    1995-10-01

    This study primarily investigates the role of competition in completely mixed anaerobic granular activated carbon (GAC) reactors treating a synthetic wastewater consisting of acetic acid, phenol, and o-cresol, and also addresses dual substrate biodegradation. The fate of the biodegradable nonadsorbable substrate followed very closely that of the biodegradable adsorbable substrate. As adsorption complemented biodegradation in this system, with the two being oppositely influenced by the GAC replacement rate, the removal of both biodegradable substrates exhibited both a maximum and minimum at GAC residence times of 30 and 12 days, respectively. On comparing the experimental capacities for o-cresol, which resisted biodegradation in the GAC reactors, with the o-cresol isotherm capacities, the effect of phenol competition for adsorption was found to be negligible when the effluent o-cresol concentrations were orders of magnitude higher than the concentrations of the biodegradable phenol. Competition effects decreased the adsorptive capacities of the reactors` GAC for o-cresol when phenol and o-cresol concentrations were of the same order of magnitude, although phenol sorptive capacities were predicted much more closely than at very low phenol concentration. The ideal adsorbed solution theory (IAST) was found to fairly describe the competition for adsorption between phenol and o-cresol despite some discrepancies between the experimental and the model-predicted capacities at low adsorbate concentrations.

  4. Field experiences VOC and pesticide removal using GAC Suffolk County, New York

    SciTech Connect

    Harris, D.; Andreoli, A.; Baier, J.H.

    1992-01-01

    Over the past eight years, Granular Activated Carbon (GAC) systems have been installed for treatment of VOC and pesticides. Several have seen multiple carbon replacement; changes in water quality; and experienced a variety of operational difficulties. The following GAC systems will be discussed: Village of Greenport - one 20,000 lb. GAC operating from 1980 to present for removal of aldicarb and carbofuran; Southold - use of GAC in series for aldicarb, carbofuran and DCP; Dix Hills Water District - three 20,000 lb. units in parallel for removal of DCP; and Suffolk County Water Authority - 4 separate well fields treating aldicarb, DCP, TCA, TCE, PCE and others, with a variety of operating experiences. Operational problems encountered with each unit will also be discussed.

  5. 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

  6. Influence of sorption on sound propagation in granular activated carbon.

    PubMed

    Venegas, Rodolfo; Umnova, Olga

    2016-08-01

    Granular activated carbon (GAC) has numerous applications due to its ability to adsorb and desorb gas molecules. Recently, it has been shown to exhibit unusually high low frequency sound absorption. This behavior is determined by both the multi-scale nature of the material, i.e., the existence of three scales of heterogeneities, and physical processes specific to micro- and nanometer-size pores, i.e., rarefaction and sorption effects. To account for these processes a model for sound propagation in GAC is developed in this work. A methodology for characterizing GAC which includes optical granulometry, flow resistivity measurements, and the derivation of the inner-particle model parameters from acoustical and non-acoustical measurements is also presented. The model agrees with measurements of normal incidence surface impedance and sound absorption coefficient on three different GAC samples. PMID:27586708

  7. 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.

  8. Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of TiO2 Nanoparticles

    EPA Science Inventory

    Nanoparticles (NPs) are emerging as a new type of contaminant in water and wastewater. The fate of titanium dioxide nanoparticles (TiO2NPs) in a granular activated carbon (GAC) adsorber and their impact on the removal of trichloroethylene (TCE) by GAC was investigated...

  9. Impacts of backwashing on granular activated carbon filters for advanced wastewater treatment.

    PubMed

    Frank, Joshua; Ruhl, Aki Sebastian; Jekel, Martin

    2015-12-15

    The use of granular activated carbon (GAC) in fixed bed filters is a promising option for the removal of organic micropollutants (OMP) from wastewater treatment plant effluents. Frequent backwashing of the filter bed is inevitable, but its effect on potential filter stratification is not well understood yet and thus has been evaluated in the present study for two commercial GAC products. Backwashing of GAC filters was simulated with 10 or 100 filter bed expansions of 20 or 100% at backwash velocities of 12 and 40 m/h, respectively. Five vertical fractions were extracted and revealed a vertical stratification according to grain sizes and material densities. Sieve analyses indicated increasing grain sizes towards the bottom for one GAC while grain sizes of the other GAC were more homogeneously distributed throughout the filter bed. The apparent densities of the top sections were significantly lower than that of the bottom sections of both products. Comparative long term fixed bed adsorption experiments with the top and bottom sections of the stratified GAC showed remarkable differences in breakthrough curves of dissolved organic carbon, UV light absorption at 254 nm wavelength (UVA254) and OMP. GAC from the upper section showed constantly better removal efficiencies than GAC from the bottom section, especially for weakly adsorbing OMP such as sulfamethoxazole. Furthermore correlations between UVA254 reductions and OMP removals were found.

  10. Impacts of backwashing on granular activated carbon filters for advanced wastewater treatment.

    PubMed

    Frank, Joshua; Ruhl, Aki Sebastian; Jekel, Martin

    2015-12-15

    The use of granular activated carbon (GAC) in fixed bed filters is a promising option for the removal of organic micropollutants (OMP) from wastewater treatment plant effluents. Frequent backwashing of the filter bed is inevitable, but its effect on potential filter stratification is not well understood yet and thus has been evaluated in the present study for two commercial GAC products. Backwashing of GAC filters was simulated with 10 or 100 filter bed expansions of 20 or 100% at backwash velocities of 12 and 40 m/h, respectively. Five vertical fractions were extracted and revealed a vertical stratification according to grain sizes and material densities. Sieve analyses indicated increasing grain sizes towards the bottom for one GAC while grain sizes of the other GAC were more homogeneously distributed throughout the filter bed. The apparent densities of the top sections were significantly lower than that of the bottom sections of both products. Comparative long term fixed bed adsorption experiments with the top and bottom sections of the stratified GAC showed remarkable differences in breakthrough curves of dissolved organic carbon, UV light absorption at 254 nm wavelength (UVA254) and OMP. GAC from the upper section showed constantly better removal efficiencies than GAC from the bottom section, especially for weakly adsorbing OMP such as sulfamethoxazole. Furthermore correlations between UVA254 reductions and OMP removals were found. PMID:26405842

  11. Modified Activated Carbon to be Used in Clinical Applications

    NASA Astrophysics Data System (ADS)

    Fernando, M. S.; de Silva, W. R. M.; de Silva, K. M. N.

    2014-11-01

    In this study a novel nano composite of hydroxyapatite nano particles impregnated activated carbon (C-HAp), which was synthesized in our own method, was used in iron adsorption studies. The study was conducted in order to investigate the potential of using C-HAp nanocomposite to be used in clinical detoxifications such as acute iron toxicity where the use of Activated carbon (GAC) is not very effective. Adsorption studies were conducted for synthetic solutions of Fe2+, Fe3+ and iron syrup using GAC, C-HAp and neat HAp as adsorbents. According to the results C-HAp nano composite showed improved properties than GAC in adsorbing Fe2+, Fe3+ and also Fe ions in iron syrup solutions. Thus the results of the in-vitro studies of iron adsorption studies indicated the potential of using C-HAp as an alternative to activated carbon in such clinical applications.

  12. Fe-Mn bi-metallic oxides loaded on granular activated carbon to enhance dye removal by catalytic ozonation.

    PubMed

    Tang, Shoufeng; Yuan, Deling; Zhang, Qi; Liu, Yameng; Zhang, Qi; Liu, Zhengquan; Huang, Haiming

    2016-09-01

    A Fe-Mn bi-metallic oxide supported on granular activated carbon (Fe-Mn GAC) has been fabricated by an impregnation-desiccation method and tested in the catalytic ozonation of methyl orange (MO) degradation and mineralization. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations revealed that Fe-Mn oxides were successfully loaded and uniformly distributed on the GAC, and nitrogen adsorption isotherms showed that the supported GAC retained a large surface area and a high pore volume compared with the pristine GAC. The catalytic activity was systematically assessed by monitoring the MO removal efficiencies at different operational parameters, such as catalyst dosage, initial solution pH, and ozone flow rate. The Fe-Mn GAC exhibited better catalytic activity relative to ozone alone and GAC alone, improving the TOC removal by 24.5 and 11.5 % and COD removal by 13.6 and 7.3 %, respectively. The reusability of the hybrid was examined over five consecutive cyclic treatments. The Fe-Mn GAC catalytic activity was only a slight loss in the cycles, showing good stability. The addition of Na2CO3 as hydroxyl radicals (•OH) scavengers proved that the catalytic ozonation mechanism was the enhanced generation of •OH by the Fe-Mn GAC. The above results render the Fe-Mn GAC an industrially promising candidate for catalytic ozonation of dye contaminant removal.

  13. Fe-Mn bi-metallic oxides loaded on granular activated carbon to enhance dye removal by catalytic ozonation.

    PubMed

    Tang, Shoufeng; Yuan, Deling; Zhang, Qi; Liu, Yameng; Zhang, Qi; Liu, Zhengquan; Huang, Haiming

    2016-09-01

    A Fe-Mn bi-metallic oxide supported on granular activated carbon (Fe-Mn GAC) has been fabricated by an impregnation-desiccation method and tested in the catalytic ozonation of methyl orange (MO) degradation and mineralization. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations revealed that Fe-Mn oxides were successfully loaded and uniformly distributed on the GAC, and nitrogen adsorption isotherms showed that the supported GAC retained a large surface area and a high pore volume compared with the pristine GAC. The catalytic activity was systematically assessed by monitoring the MO removal efficiencies at different operational parameters, such as catalyst dosage, initial solution pH, and ozone flow rate. The Fe-Mn GAC exhibited better catalytic activity relative to ozone alone and GAC alone, improving the TOC removal by 24.5 and 11.5 % and COD removal by 13.6 and 7.3 %, respectively. The reusability of the hybrid was examined over five consecutive cyclic treatments. The Fe-Mn GAC catalytic activity was only a slight loss in the cycles, showing good stability. The addition of Na2CO3 as hydroxyl radicals (•OH) scavengers proved that the catalytic ozonation mechanism was the enhanced generation of •OH by the Fe-Mn GAC. The above results render the Fe-Mn GAC an industrially promising candidate for catalytic ozonation of dye contaminant removal. PMID:27316651

  14. Removing lead in drinking water with activated carbon

    SciTech Connect

    Taylor, R.M.; Kuennen, R.W. )

    1994-02-01

    A point-of-use (POU) granular activated carbon (GAC) fixed bed adsorber (FBA) was evaluated for reduction of soluble and insoluble lead from drinking water. Some of the factors which affect lead removal by GAC were evaluated, such as carbon type, solution pH, and a limited amount of work on competitive interactions. The design criteria for lead reduction by a POU device are also addressed. Minicolumns were used to evaluate the capacity of carbon for lead under a variety of conditions. The importance of surface chemistry of the carbon and the relationship with the pH of the water for lead reduction was demonstrated. Results indicate that a properly designed POU-GAC-FBA can reduce lead in drinking water to below the EPA action level of 15 ppb while being tested under a variety of conditions as specified under the National Sanitation Foundation (NSF) International Standard 53 test protocol. 37 refs., 9 figs., 1 tab.

  15. Characterising biofilm development on granular activated carbon used for drinking water production.

    PubMed

    Gibert, Oriol; Lefèvre, Benoît; Fernández, Marc; Bernat, Xavier; Paraira, Miquel; Calderer, Montse; Martínez-Lladó, Xavier

    2013-03-01

    Under normal operation conditions, granular activated carbon (GAC) employed in drinking water treatment plants (DWTPs) for natural organic matter (NOM) removal can be colonised by microorganisms which can eventually establish active biofilms. The formation of such biofilms can contribute to NOM removal by biodegradation, but also in clogging phenomena that can make necessary more frequent backwashes. Biofilm occurrence and evolution under full-scale-like conditions (i.e. including periodic backwashing) are still uncertain, and GAC filtration is usually operated with a strong empirical component. The aim of the present study was to assess the formation and growth, if any, of biofilm in a periodically backwashed GAC filter. For this purpose, an on-site pilot plant was assembled and operated to closely mimic the GAC filters installed in the DWTP in Sant Joan Despí (Barcelona, Spain). The study comprised a monitoring of both water and GAC cores withdrawn at various depths and times throughout 1 year operation. The biomass parameters assessed were total cell count by confocal laser scanning microscopy (CLSM), DNA and adenosine triphosphate (ATP). Visual examination of GAC particles was also conducted by high-resolution field emission scanning electron microscopy (FESEM). Additionally, water quality and GAC surface properties were monitored. Results provided insight into the extent and spatial distribution of biofilm within the GAC bed. To sum up, it was found that backwashing could physically detach bacteria from the biofilm, which could however build back up to its pre-backwashing concentration before next backwashing cycle.

  16. REMOVAL OF ORGANIC CCL CONTAMINANTS FROM DRINKING WATERS BY MEMBRANE AND GAC PROCESSES

    EPA Science Inventory

    Bench-scale treatment data for membrane and granular activated carbon technologies are presented for the organic contaminants on the U.S. Environmental Protection Agency's Contaminant Candidate List (CCL). For granular activated carbon (GAC), isotherm results are presented and q...

  17. Enrichment of specific electro-active microorganisms and enhancement of methane production by adding granular activated carbon in anaerobic reactors.

    PubMed

    Lee, Jung-Yeol; Lee, Sang-Hoon; Park, Hee-Deung

    2016-04-01

    Direct interspecies electron transfer (DIET) via conductive materials can provide significant benefits to anaerobic methane formation in terms of production amount and rate. Although granular activated carbon (GAC) demonstrated its applicability in facilitating DIET in methanogenesis, DIET in continuous flow anaerobic reactors has not been verified. Here, evidences of DIET via GAC were explored. The reactor supplemented with GAC showed 1.8-fold higher methane production rate than that without GAC (35.7 versus 20.1±7.1mL-CH4/d). Around 34% of methane formation was attributed to the biomass attached to GAC. Pyrosequencing of 16S rRNA gene demonstrated the enrichment of exoelectrogens (e.g. Geobacter) and hydrogenotrophic methanogens (e.g. Methanospirillum and Methanolinea) from the biomass attached to GAC. Furthermore, anodic and cathodic currents generation was observed in an electrochemical cell containing GAC biomass. Taken together, GAC supplementation created an environment for enriching the microorganisms involved in DIET, which increased the methane production rate. PMID:26836607

  18. PCB bioavailability control in Lumbriculus variegatus through different modes of activated carbon addition to sediments

    SciTech Connect

    Xueli Sun; Upal Ghosh

    2007-07-01

    PCB bioavailability to a freshwater oligochaete (Lumbriculus variegatus) was studied using sediments from a PCB-impacted river that was treated with different modes of granular activated carbon (GAC) addition. The GAC used was bituminous coal-based type TOP. For sediment treated with 2.6% GAC and mixed for 2 min prior to L. variegatus addition, the reduction in total PCB biouptake was 70% for 75-300 {mu}m size carbon, and 92% for the 45-180 {mu}m size carbon. For the case where the GAC was placed as a thin layer on top of the sediments without mixing, the reduction in total PCB uptake was 70%. PCB biouptake kinetics study using treated and untreated sediment showed that the maximum PCB uptake in tissue was achieved at 28 days and decreased after that time. Although the absolute uptake of PCB changed over time, the percent reduction in total PCB uptake upon GAC amendment remained constant after the first few days. Our results indicated that PCB bioavailability was reduced upon the addition and little or no mixing of GAC into sediments. PCB aqueous equilibrium concentration and desorption rates were greatly reduced after GAC amendment, indicating reductions in the two primary mechanisms of PCB bioavailability in sediments: chemical activity and chemical accessibility. 29 refs., 5 figs., 1 tab.

  19. The Gac regulon of Pseudomonas fluorescens SBW25.

    PubMed

    Cheng, Xu; de Bruijn, Irene; van der Voort, Menno; Loper, Joyce E; Raaijmakers, Jos M

    2013-08-01

    Transcriptome analysis of Pseudomonas fluorescens SBW25 showed that 702 genes were differentially regulated in a gacS::Tn5 mutant, with 300 and 402 genes up- and downregulated respectively. Similar to the Gac regulon of other Pseudomonas species, genes involved in motility, biofilm formation, siderophore biosynthesis and oxidative stress were differentially regulated in the gacS mutant of SBW25. Our analysis also revealed, for the first time, that transcription of 19 rhizosphere-induced genes and of genes involved in type II secretion, (exo)polysaccharide and pectate lyase biosynthesis, twitching motility and an orphan non-ribosomal peptide synthetase (NRPS) were significantly affected in the gacS mutant. Furthermore, the gacS mutant inhibited growth of oomycete, fungal and bacterial pathogens significantly more than wild type SBW25. Since RP-HPLC analysis did not reveal any potential candidate metabolites, we focused on the Gac-regulated orphan NRPS gene cluster that was predicted to encode an eight-amino-acid ornicorrugatin-like peptide. Site-directed mutagenesis indicated that the encoded peptide is not involved in the enhanced antimicrobial activity of the gacS mutant but may function as a siderophore. Collectively, this genome-wide analysis revealed that a mutation in the GacS/A two-component regulatory system causes major transcriptional changes in SBW25 and significantly enhances its antimicrobial activities by yet unknown mechanisms.

  20. Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

    NASA Astrophysics Data System (ADS)

    Qu, Guangzhou; Liang, Dongli; Qu, Dong; Huang, Yimei; Li, Jie

    2014-06-01

    In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O3) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O3 regeneration. O3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O3 regeneration has a lower weight loss than DBD plasma regeneration.

  1. Regeneration of Acid Orange 7 Exhausted Granular Activated Carbon Using Pulsed Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Huijuan; Guo, He; Liu, Yongjie; Yi, Chengwu

    2015-10-01

    In this paper, a pulsed discharge plasma (PDP) system with a multi-needle-to-plate electrodes geometry was set up to investigate the regeneration of acid orange 7 (AO7) exhausted granular activated carbon (GAC). Regeneration of GAC was studied under different conditions of peak pulse discharge voltage and water pH, as well as the modification effect of GAC by the pulse discharge process, to figure out the regeneration efficiency and the change of the GAC structure by the PDP treatment. The obtained results showed that there was an appropriate peak pulse voltage and an optimal initial pH value of the solution for GAC regeneration. Analyses of scanning electron microscope (SEM), Boehm titration, Brunauer-Emmett-Teller (BET), Horvath-Kawazoe (HK), and X-ray Diffraction (XRD) showed that there were more mesopore and macropore in the regenerated GAC and the structure turned smoother with the increase of discharge voltage; the amount of acidic functional groups on the GAC surface increased while the amount of basic functional groups decreased after the regeneration process. From the result of the XRD analysis, there were no new substances produced on the GAC after PDP treatment. supported by National Natural Science Foundation of China (No. 21207052), China Postdoctoral Science Foundation (No. 20110491353) and Jiangsu Planned Projects for Postdoctoral Research Funds, China (No. 1102116C)

  2. 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

  3. Enhanced desalination performance of membrane capacitive deionization cells by packing the flow chamber with granular activated carbon.

    PubMed

    Bian, Yanhong; Yang, Xufei; Liang, Peng; Jiang, Yong; Zhang, Changyong; Huang, Xia

    2015-11-15

    A new design of membrane capacitive deionization (MCDI) cell was constructed by packing the cell's flow chamber with granular activated carbon (GAC). The GAC packed-MCDI (GAC-MCDI) delivered higher (1.2-2.5 times) desalination rates than the regular MCDI at all test NaCl concentrations (∼ 100-1000 mg/L). The greatest performance enhancement by packed GAC was observed when treating saline water with an initial NaCl concentration of 100 mg/L. Several different GAC materials were tested and they all exhibited similar enhancement effects. Comparatively, packing the MCDI's flow chamber with glass beads (GB; non-conductive) and graphite granules (GG; conductive but with lower specific surface area than GAC) resulted in inferior desalination performance. Electrochemical impedance spectroscopy (EIS) analysis showed that the GAC-MCDI had considerably smaller internal resistance than the regular MCDI (∼ 19.2 ± 1.2 Ω versus ∼ 1222 ± 15 Ω at 100 mg/L NaCl). The packed GAC also decreased the ionic resistance across the flow chamber (∼ 1.49 ± 0.05 Ω versus ∼ 1130 ± 12 Ω at 100 mg/L NaCl). The electric double layer (EDL) formed on the GAC surface was considered to store salt ions during electrosorption, and facilitate the ion transport in the flow chamber because of the higher ion conductivity in the EDLs than in the bulk solution, thereby enhancing the MCDI's desalination rate.

  4. Advanced treatment of biotreated textile industry wastewater with ozone, virgin/ozonated granular activated carbon and their combination.

    PubMed

    Arslan-Alaton, Idil; Seremet, Ozden

    2004-01-01

    Biotreated textile wastewater (CODo = 248 mg L(-1); TOCo = 58 mg L(-1); A620 = 0.007 cm(-1); A525 = 0.181 cm(-1); A436 = 0.198 cm(-1)) was subjected to advanced treatment with ozonation, granular activated carbon (GAC) adsorption in serial and simultaneous applications. Experiments were conducted to investigate the effects of applied ozone dose, ozone absorption rate, specific ozone absorption efficiency, GAC dose, and reaction pH on the treatment performance of the selected tertiary treatment scheme. In separate experiments, the impact of virgin GAC ozonation on its adsorptive capacity for biotreated and biotreated + ozonated textile effluent was also investigated. Ozonation appeared to be more effective for decolorization (kd = 0.15 min(-1) at pH = 3), whereas GAC adsorption yielded higher COD removal rates (54% at pH = 3). It was also found that GAC addition (4 g/L) at pH = 7 and 9 enhanced the COD abatement rate of the ozonation process significantly and that the sequential application of ozonation (at pH = 3-11, 675 mg L(-1) O3) followed by GAC adsorption (at pH = 3-7, 10 g L(-1) GAC) resulted in the highest treatment performances both in terms of color and COD reduction. Simultaneous application of GAC and ozone at acidic and alkaline pH seriously inhibited COD abatement rates as a consequence of competitive adsorption and partial oxidation of textile components and GAC. It could also be established that ozone absorption efficiency decreased after color removal was complete. Ozonation of biotreated textile wastewater with 113 mg L(-1) ozone resulted in an appreciable enhancement of GAC adsorptive capacity in terms of residual color removal. Ozonation of GAC at relatively low doses (= 10.8 mg/g GAC) did not improve its overall adsorption capacity.

  5. Effects of temperature on adsorption and oxidative degradation of bisphenol A in an acid-treated iron-amended granular activated carbon

    EPA Science Inventory

    The present study suggests a combined adsorption and Fenton oxidation using an acid treated Fe-amended granular activated carbon (Fe-GAC) for effective removal of bisphenol A in water. When the Fe-GAC adsorbs and is saturated with BPA in water, Fenton oxidation of BPA occurs in ...

  6. Equilibrium and kinetic modeling of contaminant immobilization by activated carbon amended to sediments in the field.

    PubMed

    Rakowska, Magdalena I; Kupryianchyk, Darya; Koelmans, Albert A; Grotenhuis, Tim; Rijnaarts, Huub H M

    2014-12-15

    Addition of activated carbons (AC) to polluted sediments and soils is an attractive remediation technique aiming at reducing pore water concentrations of hydrophobic organic contaminants (HOCs). In this study, we present (pseudo-)equilibrium as well as kinetic parameters for sorption of a series of PAHs and PCBs to powdered and granular activated carbons (AC) after three different sediment treatments: sediment mixed with powdered AC (PAC), sediment mixed with granular AC (GAC), and addition of GAC followed by 2 d mixing and subsequent removal ('sediment stripping'). Remediation efficiency was assessed by quantifying fluxes of PAHs towards SPME passive samplers inserted in the sediment top layer, which showed that the efficiency decreased in the order of PAC > GAC stripping > GAC addition. Sorption was very strong to PAC, with Log KAC (L/kg) values up to 10.5. Log KAC values for GAC ranged from 6.3-7.1 and 4.8-6.2 for PAHs and PCBs, respectively. Log KAC values for GAC in the stripped sediment were 7.4-8.6 and 5.8-7.7 for PAH and PCB. Apparent first order adsorption rate constants for GAC (kGAC) in the stripping scenario were calculated with a first-order kinetic model and ranged from 1.6 × 10(-2) (PHE) to 1.7 × 10(-5) d(-1) (InP). Sorption affinity parameters did not change within 9 months post treatment, confirming the longer term effectiveness of AC in field applications for PAC and GAC. PMID:25262554

  7. Reductive dehalogenation of disinfection byproducts by an activated carbon-based electrode system.

    PubMed

    Li, Yuanqing; Kemper, Jerome M; Datuin, Gwen; Akey, Ann; Mitch, William A; Luthy, Richard G

    2016-07-01

    Low molecular weight, uncharged, halogenated disinfection byproducts (DBPs) are poorly removed by the reverse osmosis and advanced oxidation process treatment units often applied for further treatment of municipal wastewater for potable reuse. Granular activated carbon (GAC) treatment effectively sorbed 22 halogenated DBPs. Conversion of the GAC to a cathode within an electrolysis cell resulted in significant degradation of the 22 halogenated DBPs by reductive electrolysis at -1 V vs. Standard Hydrogen Electrode (SHE). The lowest removal efficiency over 6 h electrolysis was for trichloromethane (chloroform; 47%) but removal efficiencies were >90% for 13 of the 22 DBPs. In all cases, DBP degradation was higher than in electrolysis-free controls, and degradation was verified by the production of halides as reduction products. Activated carbons and charcoal were more effective than graphite for electrolysis, with graphite featuring poor sorption for the DBPs. A subset of halogenated DBPs (e.g., haloacetonitriles, chloropicrin) were degraded upon sorption to the GAC, even without electrolysis. Using chloropicrin as a model, experiments indicated that this loss was attributable to the partial reduction of sorbed chloropicrin from reducing equivalents in the GAC. Reducing equivalents depleted by these reactions could be restored when the GAC was treated by reductive electrolysis. GAC treatment of an advanced treatment train effluent for potable reuse effectively reduced the concentrations of chloroform, bromodichloromethane and dichloroacetonitrile measured in the column influent to below the method detection limits. Treatment of the GAC by reductive electrolysis at -1 V vs. SHE over 12 h resulted in significant degradation of the chloroform (63%), bromodichloromethane (96%) and dichloroacetonitrile (99%) accumulated on the GAC. The results suggest that DBPs in advanced treatment train effluents could be captured and degraded continuously by reductive electrolysis

  8. [Degradation of Acid Orange 7 with Persulfate Activated by Silver Loaded Granular Activated Carbon].

    PubMed

    Wang, Zhong-ming; Huang, Tian-yin; Chen, Jia-bin; Li, Wen-wei; Zhang, Li-ming

    2015-11-01

    Granular activated carbon with silver loaded as activator (Ag/GAC) was prepared using impregnation method. N2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize the Ag/GAC, showing that silver was successfully loaded on granular activated carbon. The oxidation degradation of acid orange 7 (AO7) by the Ag/GAC activated by persulfate (PS) was investigated at ambient temperature. The influences of factors such as Ag loading, PS or Ag/GAC dosages and initial pH on the degradation of AO7 were evaluated. The results demonstrated that the degradation rate of AO7 could reach more than 95.0% after 180 min when the Ag loading content, PS/AO7 molar ratio, the Ag/GAC dosage were 12.7 mg x g(-1), 120: 1, 1.0 g x L(-1), respectively. The initial pH had significant effect on the AO7 degradation, with pH 5.0 as the optimal pH for the degradation of AO7. The possible degradation pathway was proposed for the AO7 degradation by using UV-visible spectroscopy and gas chromatography-mass spectrometry (GG/MS). The azo bond and naphthalene ring in the AO7 were destroyed during the degradation, with phthalic acid and acetophenone as the main degradation products. PMID:26910999

  9. Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality.

    PubMed

    da Silva, Flávia Vieira; Yamaguchi, Natália Ueda; Lovato, Gilselaine Afonso; da Silva, Fernando Alves; Reis, Miria Hespanhol Miranda; de Amorim, Maria Teresa Pessoa Sousa; Tavares, Célia Regina Granhen; Bergamasco, Rosângela

    2012-01-01

    This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer-Emmett-Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption.

  10. Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality.

    PubMed

    da Silva, Flávia Vieira; Yamaguchi, Natália Ueda; Lovato, Gilselaine Afonso; da Silva, Fernando Alves; Reis, Miria Hespanhol Miranda; de Amorim, Maria Teresa Pessoa Sousa; Tavares, Célia Regina Granhen; Bergamasco, Rosângela

    2012-01-01

    This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer-Emmett-Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption. PMID:22629647

  11. Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

    2016-06-01

    Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). PMID:26803903

  12. Phytochemicals and antioxidant activity of different fruit fractions (peel, pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng).

    PubMed

    Kubola, Jittawan; Siriamornpun, Sirithon

    2011-08-01

    Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene, whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp. Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions exhibited different levels of antioxidant activity in the systems tested. The aril extract showed the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature>ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed. PMID:25214106

  13. Phytochemicals and antioxidant activity of different fruit fractions (peel, pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng).

    PubMed

    Kubola, Jittawan; Siriamornpun, Sirithon

    2011-08-01

    Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene, whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp. Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions exhibited different levels of antioxidant activity in the systems tested. The aril extract showed the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature>ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed.

  14. Bacterial diversity and active biomass in full-scale granular activated carbon filters operated at low water temperatures.

    PubMed

    Kaarela, Outi E; Härkki, Heli A; Palmroth, Marja R T; Tuhkanen, Tuula A

    2015-01-01

    Granular activated carbon (GAC) filtration enhances the removal of natural organic matter and micropollutants in drinking water treatment. Microbial communities in GAC filters contribute to the removal of the biodegradable part of organic matter, and thus help to control microbial regrowth in the distribution system. Our objectives were to investigate bacterial community dynamics, identify the major bacterial groups, and determine the concentration of active bacterial biomass in full-scale GAC filters treating cold (3.7-9.5°C), physicochemically pretreated, and ozonated lake water. Three sampling rounds were conducted to study six GAC filters of different operation times and flow modes in winter, spring, and summer. Total organic carbon results indicated that both the first-step and second-step filters contributed to the removal of organic matter. Length heterogeneity analysis of amplified 16S rRNA genes illustrated that bacterial communities were diverse and considerably stable over time. α-Proteobacteria, β-Proteobacteria, and Nitrospira dominated in all of the GAC filters, although the relative proportion of dominant phylogenetic groups in individual filters differed. The active bacterial biomass accumulation, measured as adenosine triphosphate, was limited due to low temperature, low flux of nutrients, and frequent backwashing. The concentration of active bacterial biomass was not affected by the moderate seasonal temperature variation. In summary, the results provided an insight into the biological component of GAC filtration in cold water temperatures and the operational parameters affecting it. PMID:25242545

  15. Bacterial diversity and active biomass in full-scale granular activated carbon filters operated at low water temperatures.

    PubMed

    Kaarela, Outi E; Härkki, Heli A; Palmroth, Marja R T; Tuhkanen, Tuula A

    2015-01-01

    Granular activated carbon (GAC) filtration enhances the removal of natural organic matter and micropollutants in drinking water treatment. Microbial communities in GAC filters contribute to the removal of the biodegradable part of organic matter, and thus help to control microbial regrowth in the distribution system. Our objectives were to investigate bacterial community dynamics, identify the major bacterial groups, and determine the concentration of active bacterial biomass in full-scale GAC filters treating cold (3.7-9.5°C), physicochemically pretreated, and ozonated lake water. Three sampling rounds were conducted to study six GAC filters of different operation times and flow modes in winter, spring, and summer. Total organic carbon results indicated that both the first-step and second-step filters contributed to the removal of organic matter. Length heterogeneity analysis of amplified 16S rRNA genes illustrated that bacterial communities were diverse and considerably stable over time. α-Proteobacteria, β-Proteobacteria, and Nitrospira dominated in all of the GAC filters, although the relative proportion of dominant phylogenetic groups in individual filters differed. The active bacterial biomass accumulation, measured as adenosine triphosphate, was limited due to low temperature, low flux of nutrients, and frequent backwashing. The concentration of active bacterial biomass was not affected by the moderate seasonal temperature variation. In summary, the results provided an insight into the biological component of GAC filtration in cold water temperatures and the operational parameters affecting it.

  16. Removal of MIB and geosmin using granular activated carbon with and without MIEX pre-treatment.

    PubMed

    Drikas, Mary; Dixon, Mike; Morran, Jim

    2009-12-01

    This study assessed the impact of MIEX pre-treatment, followed by either coagulation or microfiltration (MF), on the effectiveness of pilot granular activated carbon (GAC) filters for the removal of the taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from a surface drinking water source over a 2-year period. Complete removal of MIB and geosmin was achieved by all GAC filters for the first 10 months, suggesting that the available adsorption capacity was sufficient to compensate for differences in dissolved organic carbon (DOC) entering the GAC filters. Reduction of empty bed contact time (EBCT), in all but one GAC filter, resulted in breakthrough of spiked MIB and geosmin, with initial results inconclusive regarding the impact of MIEX pre-treatment. MIB and geosmin removal increased over the ensuing 12 months until complete removal of both MIB and geosmin was again achieved in all but one GAC filter, which had been pre-chlorinated. Autoclaving and washing the GAC filters had minimal impact on geosmin removal but reduced MIB removal by 30% in all but the pre-chlorinated filter, confirming that biodegradation impacted MIB removal. The impact of biodegradation was greater than any impact on GAC adsorption arising from DOC differences due to MIEX pre-treatment. It is not clear whether, at a lower initial EBCT, MIEX pre-treatment may have impacted on the adsorption capacity of the virgin GAC. The GAC filter maintained at the longer EBCT, which was also pre-chlorinated, completely removed MIB and geosmin for the period of the study, suggesting that the greater adsorption capacity was compensating for any decrease in biological degradation. PMID:19744694

  17. Removal of MIB and geosmin using granular activated carbon with and without MIEX pre-treatment.

    PubMed

    Drikas, Mary; Dixon, Mike; Morran, Jim

    2009-12-01

    This study assessed the impact of MIEX pre-treatment, followed by either coagulation or microfiltration (MF), on the effectiveness of pilot granular activated carbon (GAC) filters for the removal of the taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from a surface drinking water source over a 2-year period. Complete removal of MIB and geosmin was achieved by all GAC filters for the first 10 months, suggesting that the available adsorption capacity was sufficient to compensate for differences in dissolved organic carbon (DOC) entering the GAC filters. Reduction of empty bed contact time (EBCT), in all but one GAC filter, resulted in breakthrough of spiked MIB and geosmin, with initial results inconclusive regarding the impact of MIEX pre-treatment. MIB and geosmin removal increased over the ensuing 12 months until complete removal of both MIB and geosmin was again achieved in all but one GAC filter, which had been pre-chlorinated. Autoclaving and washing the GAC filters had minimal impact on geosmin removal but reduced MIB removal by 30% in all but the pre-chlorinated filter, confirming that biodegradation impacted MIB removal. The impact of biodegradation was greater than any impact on GAC adsorption arising from DOC differences due to MIEX pre-treatment. It is not clear whether, at a lower initial EBCT, MIEX pre-treatment may have impacted on the adsorption capacity of the virgin GAC. The GAC filter maintained at the longer EBCT, which was also pre-chlorinated, completely removed MIB and geosmin for the period of the study, suggesting that the greater adsorption capacity was compensating for any decrease in biological degradation.

  18. Adsorption behavior of alpha -cypermethrin on cork and activated carbon.

    PubMed

    Domingues, Valentina F; Priolo, Giuseppe; Alves, Arminda C; Cabral, Miguel F; Delerue-Matos, Cristina

    2007-08-01

    Studies were undertaken to determine the adsorption behavior of alpha -cypermethrin [R)-alpha -cyano-3-phenoxybenzyl(1S)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, and (S)-alpha-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] in solutions on granules of cork and activated carbon (GAC). The adsorption studies were carried out using a batch equilibrium technique. A gas chromatograph with an electron capture detector (GC-ECD) was used to analyze alpha -cypermethrin after solid phase extraction with C18 disks. Physical properties including real density, pore volume, surface area and pore diameter of cork were evaluated by mercury porosimetry. Characterization of cork particles showed variations thereby indicating the highly heterogeneous structure of the material. The average surface area of cork particles was lower than that of GAC. Kinetics adsorption studies allowed the determination of the equilibrium time - 24 hours for both cork (1-2 mm and 3-4 mm) and GAC. For the studied alpha -cypermethrin concentration range, GAC revealed to be a better sorbent. However, adsorption parameters for equilibrium concentrations, obtained through the Langmuir and Freundlich models, showed that granulated cork 1-2 mm have the maximum amount of adsorbed alpha-cypermethrin (q(m)) (303 microg/g); followed by GAC (186 microg/g) and cork 3-4 mm (136 microg/g). The standard deviation (SD) values, demonstrate that Freundlich model better describes the alpha -cypermethrin adsorption phenomena on GAC, while alpha -cypermethrin adsorption on cork (1-2 mm and 3-4 mm) is better described by the Langmuir. In view of the adsorption results obtained in this study it appears that granulated cork may be a better and a cheaper alternative to GAC for removing alpha -cypermethrin from water.

  19. Effect of GAC pre-treatment and disinfectant on microbial community structure and opportunistic pathogen occurrence.

    PubMed

    Wang, Hong; Pryor, Marsha A; Edwards, Marc A; Falkinham, Joseph O; Pruden, Amy

    2013-10-01

    Opportunistic pathogens in potable water systems are an emerging health concern; however, the factors influencing their proliferation are poorly understood. Here we investigated the effects of prior granular activated carbon (GAC) biofiltration [GAC-filtered water, unfiltered water, and a blend (30% GAC filtered and 70% unfiltered water)] and disinfectant type (chlorine, chloramine) on opportunistic pathogen occurrence using five annular reactors (ARs) to simulate water distribution systems, particularly premise plumbing. GAC pre-treatment effectively reduced total organic carbon (TOC), resulting in three levels of influent TOC investigated. Quantitative polymerase chain reaction (q-PCR) provided molecular evidence of natural colonization of Legionella spp., Mycobacterium spp., Acanthamoeba spp., Hartmannella vermiformis and Mycobacterium avium on AR coupons. Cultivable mycobacteria and amoeba, including pathogenic species, were also found in bulk water and biofilm samples. While q-PCR tends to overestimate live cells, it provided a quantitative comparison of target organisms colonizing the AR biofilms in terms of gene copy numbers. In most cases, total bacteria and opportunistic pathogens were higher in the three undisinfected ARs, but the levels were not proportional to the level of GAC pre-treatment/TOC. Chlorine was more effective for controlling mycobacteria and Acanthamoeba, whereas chloramine was more effective for controlling Legionella. Both chlorine and chloramine effectively inhibited M. avium and H. vermiformis colonization. Pyrosequencing of 16S rRNA genes in coupon biofilms revealed a significant effect of GAC pre-treatment and disinfectant type on the microbial community structure. Overall, this study provides insights into the potential of different disinfectants and GAC biofilters at the treatment plant and in buildings to control downstream opportunistic pathogens and broader drinking water microbial communities.

  20. EVALUATING THE COSTS OF PACKED-TOWER AERATION AND GAC FOR CONTROLLING SELECTED ORGANICS

    EPA Science Inventory

    This article focuses on a preliminary cost analysis that compares liquid-phase granular activated carbon (GAC) treatment with packed-tower aeration (PTA) treatment, with and without air emissions control. The sensitivity of cost to design and operating variables is also discussed...

  1. Novel electro-fenton approach for regeneration of activated carbon.

    PubMed

    Bañuelos, Jennifer A; Rodríguez, Francisco J; Manríquez Rocha, Juan; Bustos, Erika; Rodríguez, Adrián; Cruz, Julio C; Arriaga, L G; Godínez, Luis A

    2013-07-16

    An electro-Fenton-based method was used to promote the regeneration of granular activated carbon (GAC) previously adsorbed with toluene. Electrochemical regeneration experiments were carried out using a standard laboratory electrochemical cell with carbon paste electrodes and a batch electrochemical reactor. For each system, a comparison was made using FeSO4 as a precursor salt in solution (homogeneous system) and an Fe-loaded ion-exchange resin (Purolite C-100, heterogeneous system), both in combination with electrogenerated H2O2 at the GAC cathode. In the two cases, high regeneration efficiencies were obtained in the presence of iron using appropriate conditions of applied potential and adsorption-polarization time. Consecutive loading and regeneration cycles of GAC were performed in the reactor without great loss of the adsorption properties, only reducing the regeneration efficiency by 1% per cycle during 10 cycles of treatment. Considering that, in the proposed resin-containing process, the use of Fe salts is avoided and that GAC cathodic polarization results in efficient cleaning and regeneration of the adsorbent material, this novel electro-Fenton approach could constitute an excellent alternative for regenerating activated carbon when compared to conventional methods. PMID:23782426

  2. TAILORING ACTIVATED CARBONS FOR ENHANCED REMOVAL OF NATURAL ORGANIC MATTER FROM NATURAL WATERS. (R828157)

    EPA Science Inventory

    Several pathways have been employed to systematically modify two granular activated carbons (GACs), F400 (coal-based) and Macro (wood-based), for examining adsorption of dissolved natural organic matter (DOM) from natural waters. A total of 24 activated carbons with different ...

  3. The Implications of Fe2O3 and TiO2 Nanoparticles on the Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of Humic Acid

    EPA Science Inventory

    The implications of Fe2O3 and TiO2 nanoparticles (NPs) on a granular activated carbon (GAC) adsorber and their impact on the removal of Trichloroethylene (TCE) were investigated in the presence of humic acid (HA). The surface charge of the GAC and NPs was obtained in the presence...

  4. Wet oxidative regeneration of activated carbon loaded with reactive dye.

    PubMed

    Shende, R V; Mahajani, V V

    2002-01-01

    Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution.

  5. Wet oxidative regeneration of activated carbon loaded with reactive dye.

    PubMed

    Shende, R V; Mahajani, V V

    2002-01-01

    Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution. PMID:11942707

  6. Effect of chloroethene concentrations and granular activated carbon on reductive dechlorination rates and growth of Dehalococcoides spp.

    PubMed

    Aktaş, Özgür; Schmidt, Kathrin R; Mungenast, Sarah; Stoll, Claudia; Tiehm, Andreas

    2012-01-01

    This study focused on the investigation of (i) the tetrachloroethene (PCE) toxicity threshold of a reductively dechlorinating mixed culture containing Dehalococcoides spp., (ii) the adsorption of PCE on different types of granular activated carbon (GAC), and (iii) the bioavailability and reductive dechlorination in the presence of GAC. The abundance of Dehalococcoides spp. detected by quantitative real-time polymerase chain reaction (qPCR) was found to increase by 2-4 orders of magnitude during degradation of PCE. No degradation occurred at dissolved concentrations beyond 420 μM (70 mg/L). Different adsorption isotherms were determined for thermally and chemically activated carbons. The addition of GAC to biological assays reduced the dissolved PCE concentration below the toxicity threshold. The combination of microbial reductive dechlorination with GAC adsorption proved to be a promising method for remediation of groundwater contaminated by high concentrations of chloroethenes.

  7. Bacterial Community Structure Shifted by Geosmin in Granular Activated Carbon System of Water Treatment Plants.

    PubMed

    Pham, Ngoc Dung; Lee, Eun-Hee; Chae, Seon-Ha; Cho, Yongdeok; Shin, Hyejin; Son, Ahjeong

    2016-01-01

    We investigated the relation between the presence of geosmin in water and the bacterial community structure within the granular activated carbon (GAC) system of water treatment plants in South Korea. GAC samples were collected in May and August of 2014 at three water treatment plants (Sungnam, Koyang, and Yeoncho in Korea). Dissolved organic carbon and geosmin were analyzed before and after GAC treatment. Geosmin was found in raw water from Sungnam and Koyang water treatment plants but not in that from Yeoncho water treatment plant. Interestingly, but not surprisingly, the 16S rRNA clone library indicated that the bacterial communities from the Sungnam and Koyang GAC systems were closely related to geosmin-degrading bacteria. Based on the phylogenetic tree and multidimensional scaling plot, bacterial clones from GAC under the influence of geosmin were clustered with Variovorax paradoxus strain DB 9b and Comamonas sp. DB mg. In other words, the presence of geosmin in water might have inevitably contributed to the growth of geosmin degraders within the respective GAC system.

  8. Preloading hydrous ferric oxide into granular activated carbon for arsenic removal.

    PubMed

    Jang, Min; Chen, Weifang; Cannon, Fred S

    2008-05-01

    Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal. PMID:18522120

  9. Microbiological Analysis of an Active Pilot-Scale Mobile Bioreactor Treating Organic Contaminants

    SciTech Connect

    Brigmon, R.L.

    1997-11-26

    Samples were obtained for microbiological analysis from a granular activated carbon fluidized bed bioreactor (GAC-FBR). This GAC-FBR was in operation at a former manufactured gas plant (MGP) Site in Augusta Georgia for in situ groundwater bioremediation of organics. The samples included contaminated site groundwater, GAC-FBR effluent, and biofilm coated granular activated carbon at 5, 9, and 13 feet within the GAC-FBR column. The objective of this analysis was to correlate contaminant removal with microbiological activity within the GAC-FBR.

  10. Arsenic adsorption and speciation in drinking water by GAC-based iron-containing adsorbents

    NASA Astrophysics Data System (ADS)

    Gim, Yewon; Terry, Jeff; Gu, Zhimang; Hua, B.; Deng, Baolin

    2008-04-01

    Granular Activated Carbon (GAC) with Iron adsorbents were developed for effective removal of arsenic from drinking water. The structure and proposed mechanism for As removal was studied using X-ray absorption spectroscopy. The oxidation state of As(III)GAC sample was calculated using XANES spectra and verified to be predominantly As(V). The structure was determined using EXAFS spectra of As(V) and Fe. The Fe spectra suggested thin layer of Fe oxide formation on GAC surface. As data showed As oxide formed bond on the Fe oxide surface. The spectra were calculated using multiple geometrically optimized models calculated using density functional theory. Further calculations were done to verify the structure, and further examine the structure.

  11. Comparing activated carbon of different particle sizes on enhancing methane generation in upflow anaerobic digester.

    PubMed

    Xu, Suyun; He, Chuanqiu; Luo, Liwen; Lü, Fan; He, Pinjing; Cui, Lifeng

    2015-11-01

    Two sizes of conductive particles, i.e. 10-20 mesh granulated activated carbon (GAC) and 80-100 mesh powdered activated carbon (PAC) were added into lab-scale upflow anaerobic sludge blanket reactors, respectively, to testify their enhancement on the syntrophic metabolism of alcohols and volatile fatty acids (VFAs) in 95days operation. When OLR increased to more than 5.8gCOD/L/d, the differences between GAC/PAC supplemented reactors and the control reactor became more significant. The introduction of activated carbon could facilitate the enrichment of methanogens and accelerate the startup of methanogenesis, as indicated by enhanced methane yield and substrate degradation. High-throughput pyrosequencing analysis showed that syntrophic bacteria and Methanosarcina sp. with versatile metabolic capability increased in the tightly absorbed fraction on the PAC surface, leading to the promoted syntrophic associations. Thus PAC prevails over than GAC for methanogenic reactor with heavy load. PMID:26298405

  12. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations.

  13. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations. PMID:24729067

  14. Characterization of advanced oxidation regenerated GACs

    SciTech Connect

    Singh, J.; Cannon, F.S.

    1995-11-01

    Industrial and manufacturing processes that employ organic solvents, such as pharmaceutical production, spray booth coating applications, and petrochemical processing, constitute a major source of airborne volatile organic contaminants (VOCs) and hazardous air pollutants (HAPs). VOCs released into the atmosphere react with sunlight to create photochemical smog, oxidants and other pollutants, all of which are considered harmful to animal and plant life. There is thus a need for effective air pollution remediation technologies for such facilities. This paper explores the effects of regeneration by means of advanced oxidation involving UV and ozone, on several properties of granular activated carbons (GACs). The effects of reduction in surface areas and pore volumes, and surface oxidation due to this process of regeneration, on adsorption capacities of some model VOCs is investigated.

  15. Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems.

    PubMed

    Paredes, L; Fernandez-Fontaina, E; Lema, J M; Omil, F; Carballa, M

    2016-05-01

    In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters. PMID:26897407

  16. The Hybrid Histidine Kinase LadS Forms a Multicomponent Signal Transduction System with the GacS/GacA Two-Component System in Pseudomonas aeruginosa

    PubMed Central

    Redelberger, David; Fadel, Firas; Filloux, Alain; Sivaneson, Melissa; de Bentzmann, Sophie; Bordi, Christophe

    2016-01-01

    In response to environmental changes, Pseudomonas aeruginosa is able to switch from a planktonic (free swimming) to a sessile (biofilm) lifestyle. The two-component system (TCS) GacS/GacA activates the production of two small non-coding RNAs, RsmY and RsmZ, but four histidine kinases (HKs), RetS, GacS, LadS and PA1611, are instrumental in this process. RetS hybrid HK blocks GacS unorthodox HK autophosphorylation through the formation of a heterodimer. PA1611 hybrid HK, which is structurally related to GacS, interacts with RetS in P. aeruginosa in a very similar manner to GacS. LadS hybrid HK phenotypically antagonizes the function of RetS by a mechanism that has never been investigated. The four sensors are found in most Pseudomonas species but their characteristics and mode of signaling may differ from one species to another. Here, we demonstrated in P. aeruginosa that LadS controls both rsmY and rsmZ gene expression and that this regulation occurs through the GacS/GacA TCS. We additionally evidenced that in contrast to RetS, LadS signals through GacS/GacA without forming heterodimers, either with GacS or with RetS. Instead, we demonstrated that LadS is involved in a genuine phosphorelay, which requires both transmitter and receiver LadS domains. LadS signaling ultimately requires the alternative histidine-phosphotransfer domain of GacS, which is here used as an Hpt relay by the hybrid kinase. LadS HK thus forms, with the GacS/GacA TCS, a multicomponent signal transduction system with an original phosphorelay cascade, i.e. H1LadS→D1LadS→H2GacS→D2GacA. This highlights an original strategy in which a unique output, i.e. the modulation of sRNA levels, is controlled by a complex multi-sensing network to fine-tune an adapted biofilm and virulence response. PMID:27176226

  17. Next-Generation Pyrosequencing Analysis of Microbial Biofilm Communities on Granular Activated Carbon in Treatment of Oil Sands Process-Affected Water

    PubMed Central

    Islam, M. Shahinoor; Zhang, Yanyan; McPhedran, Kerry N.

    2015-01-01

    The development of biodegradation treatment processes for oil sands process-affected water (OSPW) has been progressing in recent years with the promising potential of biofilm reactors. Previously, the granular activated carbon (GAC) biofilm process was successfully employed for treatment of a large variety of recalcitrant organic compounds in domestic and industrial wastewaters. In this study, GAC biofilm microbial development and degradation efficiency were investigated for OSPW treatment by monitoring the biofilm growth on the GAC surface in raw and ozonated OSPW in batch bioreactors. The GAC biofilm community was characterized using a next-generation 16S rRNA gene pyrosequencing technique that revealed that the phylum Proteobacteria was dominant in both OSPW and biofilms, with further in-depth analysis showing higher abundances of Alpha- and Gammaproteobacteria sequences. Interestingly, many known polyaromatic hydrocarbon degraders, namely, Burkholderiales, Pseudomonadales, Bdellovibrionales, and Sphingomonadales, were observed in the GAC biofilm. Ozonation decreased the microbial diversity in planktonic OSPW but increased the microbial diversity in the GAC biofilms. Quantitative real-time PCR revealed similar bacterial gene copy numbers (>109 gene copies/g of GAC) for both raw and ozonated OSPW GAC biofilms. The observed rates of removal of naphthenic acids (NAs) over the 2-day experiments for the GAC biofilm treatments of raw and ozonated OSPW were 31% and 66%, respectively. Overall, a relatively low ozone dose (30 mg of O3/liter utilized) combined with GAC biofilm treatment significantly increased NA removal rates. The treatment of OSPW in bioreactors using GAC biofilms is a promising technology for the reduction of recalcitrant OSPW organic compounds. PMID:25841014

  18. Regeneration of granular activated carbon saturated with acetone and isopropyl alcohol via a recirculation process under H2O2/UV oxidation.

    PubMed

    Horng, Richard S; Tseng, I-Chin

    2008-06-15

    This study examines a water-based system, coupling an adsorber and a photoreactor, for regeneration of granular activated carbon (GAC) saturated with acetone and isopropyl alcohol (IPA). Through water recirculation the regeneration reaction was operated in both intermittent and continuous ultraviolet illumination modes. With a periodic dosage of hydrogen peroxide not only was regeneration efficient but it was also catalyzed by GAC in the adsorber. The concentrations of acetone, solution chemical oxygen demand (COD), pH and organic residues on GAC surfaces were measured during regenerations. Both pH and solution COD were found to correlate with regeneration completion as measured by organic residue on GAC surfaces in four regeneration cycles with acetone. Solution pH decreased to the acidic values and then returned to near its original value when organic residues were 0.085-0.255 mg/g GAC, that is, destruction efficiency of adsorbed acetone on the GAC surface was more than 99%. Likewise, solution COD became low (<100 mg/l) at regeneration completion. The pH variation pattern was then applied to another four cycles of regeneration with IPA, and successfully reflected the timing of complete regeneration. The final levels of organic residue on GAC surfaces were between 0.135 and 0.310 mg/g GAC in each of four regeneration cycles, each of which had been stopped based on the measurements of pH and solution COD. Furthermore, nearly the same batch of GAC could be repeatedly used with little changes in physicochemical properties in each of eight cycles: adsorptive capacities were 95+/-7 mg acetone/g GAC and 87+/-3 mg IPA/g GAC, and breakthrough time was 0.86+/-0.05 for acetone and 0.78+/-0.03 h for IPA. An economic assessment of the system showed that the operating cost was about 0.04 USD for treating every gram of acetone in the air.

  19. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs) naproxen and carbamazepine and one endocrine disrupting compound (EDC) nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. The GAC adsorbents were coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. 25 refs., 4 figs., 1 tab.

  20. Biological activation of carbon filters.

    PubMed

    Seredyńska-Sobecka, Bozena; Tomaszewska, Maria; Janus, Magdalena; Morawski, Antoni W

    2006-01-01

    To prepare biological activated carbon (BAC), raw surface water was circulated through granular activated carbon (GAC) beds. Biological activity of carbon filters was initiated after about 6 months of filter operation and was confirmed by two methods: measurement of the amount of biomass attached to the carbon and by the fluorescein diacetate (FDA) test. The effect of carbon pre-washing on WG-12 carbon properties was also studied. For this purpose, the nitrogen adsorption isotherms at 77K and Fourier transform-infrared (FT-IR) spectra analyses were performed. Moreover, iodine number, decolorizing power and adsorption properties of carbon in relation to phenol were studied. Analysis of the results revealed that after WG-12 carbon pre-washing its BET surface increased a little, the pH value of the carbon water extract decreased from 11.0 to 9.4, decolorizing power remained at the same level, and the iodine number and phenol adsorption rate increased. In preliminary studies of the ozonation-biofiltration process, a model phenol solution with concentration of approximately 10mg/l was applied. During the ozonation process a dose of 1.64 mg O(3)/mg TOC (total organic carbon) was employed and the contact time was 5 min. Four empty bed contact times (EBCTs) in the range of 2.4-24.0 min were used in the biofiltration experiment. The effectiveness of purification was measured by the following parameters: chemical oxygen demand (COD(Mn)), TOC, phenol concentration and UV(254)-absorbance. The parameters were found to decrease with EBCT. PMID:16376966

  1. Effects of granular activated carbon on methane removal performance and methanotrophic community of a lab-scale bioreactor.

    PubMed

    Lee, Eun-Hee; Choi, Sun-Ah; Yi, Taewoo; Kim, Tae Gwan; Lee, Sang-Don; Cho, Kyung-Suk

    2015-01-01

    Two identical lab-scale bioreactor systems were operated to examine the effects of granular activated carbon (GAC) on methane removal performance and methanotrophic community. Both bioreactor systems removed methane completely at a CH4 loading rate of 71.2 g-CH4·d(-1) for 17 days. However, the methane removal efficiency declined to 88% in the bioreactor without GAC, while the bioreactor amended with GAC showed greater methane removal efficiency of 97% at a CH4 loading rate of 107.5 g-CH4·d(-1). Although quantitative real-time PCR showed that methanotrophic populations were similar levels of 5-10 × 10(8) pmoA gene copy number·VSS(-1) in both systems, GAC addition changed the methanotrophic community composition of the bioreactor systems. Microarray assay revealed that GAC enhanced the type I methanotrophic genera including Methylobacter, Methylomicrobium, and Methylomonas of the system, which suggests that GAC probably provided a favorable environment for type I methanotrophs. These results indicated that GAC is a promising support material in bioreactor systems for CH4 mitigation.

  2. Granular activated carbon for simultaneous adsorption and biodegradation of toxic oil sands process-affected water organic compounds.

    PubMed

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

    2015-04-01

    Naphthenic acids (NAs) released into oil sands process-affected water (OSPW) during bitumen processing in Northern Alberta are problematic for oil sands industries due to their toxicity in the environment and resistance to degradation during conventional wastewater treatment processes. Granular activated carbon (GAC) has shown to be an effective media in removing biopersistent organics from wastewater using a combination of adsorption and biodegradation removal mechanisms. A simultaneous GAC (0.4 g GAC/L) adsorption and biodegradation (combined treatment) study was used for the treatment of raw and ozonated OSPW. After 28 days of batch treatment, classical and oxidized NAs removals for raw OSPW were 93.3% and 73.7%, and for ozonated OSPW were 96.2% and 77.1%, respectively. Synergetic effects of the combined treatment process were observed in removals of COD, the acid extractable fraction, and oxidized NAs, which indicated enhanced biodegradation and bioregeneration in GAC biofilms. A bacteria copy number >10(8) copies/g GAC on GAC surfaces was found using quantitative real time polymerase chain reaction after treatment for both raw and ozonated OSPW. A Microtox(®) acute toxicity test (Vibrio fischeri) showed effective toxicity removal (>95.3%) for the combined treatments. Therefore, the simultaneous GAC adsorption and biodegradation treatment process is a promising technology for the elimination of toxic OSPW NAs.

  3. Removal of arsenic and methylene blue from water by granular activated carbon media impregnated with zirconium dioxide nanoparticles.

    PubMed

    Sandoval, Robert; Cooper, Anne Marie; Aymar, Kathryn; Jain, Arti; Hristovski, Kiril

    2011-10-15

    This study investigated the effects of in situ ZrO(2) nanoparticle formation on properties of granulated activated carbon (GAC) and their impacts on arsenic and organic co-contaminant removal. Bituminous and lignite based zirconium dioxide impregnated GAC (Zr-GAC) media were fabricated by hydrolysis of zirconium salt followed by annealing of the product at 400 °C in an inert environment. Media characterization suggested that GAC type does not affect the crystalline structure of the resulting ZrO(2) nanoparticles, but does affect zirconium content of the media, nanoparticle morphology, nanoparticle distribution, and surface area of Zr-GAC. The arsenic removal performance of both media was compared using 5mM NaHCO(3) buffered ultrapure water and model groundwater containing competing ions, both with an initial arsenic C(0) ≈ 120 μg/L. Experimental outcomes suggested favorable adsorption energies and higher or similar adsorption capacities than commercially available or experimental adsorbents when compared on the basis of metal content. Short bed adsorber column tests showed that arsenic adsorption capacity decreases as a result of kinetics of competing ions. Correlation between the properties of the media and arsenic and methylene blue removal suggested that surface area and GAC type may be the dominant factors controlling the arsenic and organic co-contaminant removal performance of the fabricated Zr-GAC media.

  4. Performance evaluation of granular activated carbon system at Pantex: Rapid small-scale column tests to simulate removal of high explosives from contaminated groundwater

    SciTech Connect

    Henke, J.L.; Speitel, G.E.

    1998-08-01

    A granular activated carbon (GAC) system is now in operation at Pantex to treat groundwater from the perched aquifer that is contaminated with high explosives. The main chemicals of concern are RDX and HMX. The system consists of two GAC columns in series. Each column is charged with 10,000 pounds of Northwestern LB-830 GAC. At the design flow rate of 325 gpm, the hydraulic loading is 6.47 gpm/ft{sup 2}, and the empty bed contact time is 8.2 minutes per column. Currently, the system is operating at less than 10% of its design flow rate, although flow rate increases are expected in the relatively near future. This study had several objectives: Estimate the service life of the GAC now in use at Pantex; Screen several GACs to provide a recommendation on the best GAC for use at Pantex when the current GAC is exhausted and is replaced; Determine the extent to which natural organic matter in the Pantex groundwater fouls GAC adsorption sites, thereby decreasing the adsorption capacity for high explosives; and Determine if computer simulation models could match the experimental results, thereby providing another tool to follow system performance.

  5. Destruction of methyl bromide sorbed to activated carbon by thiosulfate or electrolysis.

    PubMed

    Yang, Yu; Li, Yuanqing; Walse, Spencer S; Mitch, William A

    2015-04-01

    Methyl bromide (CH3Br) is widely used as a fumigant for postharvest and quarantine applications for agricultural products at port facilities due to the short treatment period required, but it is vented from fumigation chambers to the atmosphere after its use. Due to the potential contributions of CH3Br to stratospheric ozone depletion, technologies for the capture and degradation of the CH3Br are needed to enable its continued use. Although granular activated carbon (GAC) has been used for CH3Br capture and thiosulfate has been used for destruction of CH3Br in aqueous solution, this research explored techniques for direct destruction of CH3Br sorbed to GAC. Submerging the GAC in an aqueous thiosulfate solution achieved debromination of CH3Br while sorbed to the GAC, but it required molar concentrations of thiosulfate because of the high CH3Br loading and produced substantial concentrations of methyl thiosulfate. Submergence of the GAC in water and use of the GAC as the cathode of an electrolysis unit also debrominated sorbed CH3Br. The reaction appeared to involve a one-electron transfer, producing methyl radicals that incorporated into the GAC. Destruction rates increased with decreasing applied voltage down to ∼-1.2 V vs the standard hydrogen electrode. Cycling experiments conducted at -0.77 V indicated that >80% debromination of CH3Br was achieved over ∼ 30 h with ∼ 100% Coulombic efficiency. Sorptive capacity and degradation efficiency were maintained over at least 3 cycles. Capture of CH3Br fumes from fumigation chambers onto GAC, and electrolytic destruction of the sorbed CH3Br could mitigate the negative impacts of CH3Br usage pending the development of suitable replacement fumigants. PMID:25789797

  6. Optimization of low energy sonication treatment for granular activated carbon colonizing biomass assessment.

    PubMed

    Saccani, G; Bernasconi, M; Antonelli, M

    2014-01-01

    This study is aimed at optimizing a low energy sonication (LES) treatment for granular activated carbon (GAC)-colonizing biomass detachment and determination, evaluating detachment efficiency and the effects of ultrasound exposure on bacterial cell viability. GAC samples were collected from two filters fed with groundwater. Conventional heterotrophic plate count (HPC) and fluorescence microscopy with a double staining method were used to evaluate cell viability, comparing two LES procedures, without and with periodical bulk substitution. A 20 min LES treatment, with bulk substitution after cycles of 5 min as maximum treatment time, allowed to recover 87%/100% of attached biomass, protecting detached bacteria from ultrasound damaging effects. Observed viable cell inactivation rate was 6.5/7.9% cell/min, with membrane-compromised cell damage appearing to be even higher (11.5%/13.1% cell/min). Assessing bacterial detachment and damaging ultrasound effects, fluorescence microscopy turned out to be more sensitive compared to conventional HPC. The optimized method revealed a GAC-colonizing biomass of 9.9 x 10(7) cell/gGAC for plant 1 and 8.8 x 10(7) cell/gGAC for plant 2, 2 log lower than reported in literature. The difference between the two GAC-colonizing biomasses is higher in terms of viable cells (46.3% of total cells in plant 1 GAC-colonizing biomass compared to the 33.3% in plant 2). Studying influent water contamination through multivariate statistical analyses, apossible combined toxic and genotoxic effect of chromium VI and trichloroethylene was suggested as a reason for the lower viable cell fraction observed in plant 2 GAC-colonizing population.

  7. Bright luminescence of Vibrio fischeri aconitase mutants reveals a connection between citrate and the Gac/Csr regulatory system.

    PubMed

    Septer, Alecia N; Bose, Jeffrey L; Lipzen, Anna; Martin, Joel; Whistler, Cheryl; Stabb, Eric V

    2015-01-01

    The Gac/Csr regulatory system is conserved throughout the γ-proteobacteria and controls key pathways in central carbon metabolism, quorum sensing, biofilm formation and virulence in important plant and animal pathogens. Here we show that elevated intracellular citrate levels in a Vibrio fischeri aconitase mutant correlate with activation of the Gac/Csr cascade and induction of bright luminescence. Spontaneous or directed mutations in the gene that encodes citrate synthase reversed the bright luminescence of aconitase mutants, eliminated their citrate accumulation and reversed their elevated expression of CsrB. Our data elucidate a correlative link between central metabolic and regulatory pathways, and they suggest that the Gac system senses a blockage at the aconitase step of the tricarboxylic acid cycle, either through elevated citrate levels or a secondary metabolic effect of citrate accumulation, and responds by modulating carbon flow and various functions associated with host colonization, including bioluminescence.

  8. Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.

    PubMed

    Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

    2015-01-01

    Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a drinking water treatment plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests was performed at the laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests was performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 min after ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, mesoporous GAC. Therefore, this carbon removes organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and UV absorbance at wavelength 254 nm using mineral carbons; therefore, the use of a mineral mesoporous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP.

  9. [Diversity and bacteria community structure of activated carbon used in advanced drinking water treatment].

    PubMed

    Wang, Min; Shang, Hai-tao; Hao, Chun-bo; Luo, Peng; Gu, Jun-nong

    2011-05-01

    Two granular activated carbon (GAC) samples with 1.5 a and 5 a age were collected, Bacterial genome DNA was extracted for the 16S rDNA gene amplification, and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of two activated carbon biofilm sample were studied. The results showed the bacteria in GAC with 5 a age could be divided into 11 groups, which were as follows alpha-Proteobacteria (26.5%), beta-Proteobacteria (16.3%), delta-Proteobacteria (16.3%), Planctomycetes (12.2%), Gemmatimonadetes (6.1%), Acidobacteria (4.1%), Nitrospira (2.0%), gamma-Proteobacteria (2.0%), Bacteroidetes (2.0%), Actinobacteria (2.0%), Unclassified Bacteria (10.2%). The bacteria in GAC with 1.5 a age could be divided into 10 groups, which were as follows alpha-Proteobacteria (21.6%), Planctomycetes( 10.8%), Bacteroidetes (10.8%), beta-Proteobacteria (9.0%), Acidobacteria (9.0%), Nitrospira (7.2%), detla-Proteobacteria (7.2%), Unclassified Proteobacteria (5.4%), Gemmatimonadetes (3.6%), Unclassified Bacteria (14.4%). The results revealed a variety of bacterial divisions on the studied GAC biofilm. Proteobacteria had the highest share in the two total clones, and alpha- and beta-Proteobacteria were on a dominant position. A relatively high proportion of delta-Proteobacteria was observed in the biofilm of GAC with 5 a age, and Nitrospira was in a minor proportion. However, a totally converse condition appeared in GAC with 1.5 a age. Two pathogenic bacteria, Afipia and Chryseobacterium, were detected in analyzed GACs, which implies a potential microbial risk in water supply.

  10. EFFECT OF MOLECULAR OXYGEN ON ADSORPTIVE CAPACITY AND EXTRACTION EFFICIENCY OF GRANULATED ACTIVATED CARBON FOR THREE ORTHO-SUBSTITUTED PHENOLS

    EPA Science Inventory

    Adsorptive capacity of activated carbon for several organic compounds was found to be strongly influenced by the presence of molecular oxygen. This influence is manifested by the polymerization of adsorbate on the surface of activated carbon. As a result, GAC exhibits much high...

  11. Microwave pyrolysis of oily sludge with activated carbon.

    PubMed

    Chen, Yi-Rong

    2016-12-01

    The aim of this study is to explore catalytic microwave pyrolysis of crude oil storage tank sludge for fuels using granular activated carbon (GAC) as a catalyst. The effect of GAC loading on the yield of pyrolysis products was also investigated. Heating rate of oily sludge and yield of microwave pyrolysis products such as oil and fuel gas was found to depend on the ratio of GAC to oily sludge. The optimal GAC loading was found to be 10%, while much smaller and larger feed sizes adversely influenced production. During oily sludge pyrolysis, a maximum oil yield of 77.5% was achieved. Pyrolytic oils with high concentrations of diesel oil and gasoline (about 70 wt% in the pyrolytic oil) were obtained. The leaching of heavy metals, such as Cr, As and Pb, was also suppressed in the solid residue after pyrolysis. This technique provides advantages such as harmless treatment of oily sludge and substantial reduction in the consumption of energy, time and cost.

  12. Removal of Trihalomethanes by Dual Filtering Media (GAC-Sand) at El-Manshia Water Purification Plant.

    PubMed

    Mohamed, Manal A; Hassan, Ahmed H; El Messiry, Mamdouh A; Hazzaa, Reham A

    2006-01-01

    Prechlorination is used as an initial step in water purification for public supply. One of the drawbacks of the prechlorination is the reaction between natural organic matters with chlorine forming trihalmethanes. This study aims at evaluating the performance of granular activated carbon (GAC) with sand as a dual filtering media with different depths on removal of trihalomethanes (THMs) for improving water quality. The Czeck sand filter at El-Manshia Water Purification Plant was chosen in this study in order to improve its water quality. The pilot filter was designed to work as mono medium sand filter and dual GAC-Sand media. The depths of GAC were 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, and 40 cm over 115 cm, 110 cm, 105 cm, 100 cm, 90 cm, and 80 cm of sand, respectively. The six filter depths of GAC in the dual filter were studied to choose the optimum depth of GAC to improve water quality especially for THMs removal and comparing with mono-sand media and with Czeck filter. The results showed that the GAC-Sand dual media filter of 30 cm depth of GAC and 90 cm sand was the best depth for improving water quality where it was efficient in adsorbing mostly the total trihalomethanes in which its percentage of removal was 87%. The filtered water turbidity had an average of 0.3 NTU and its percentage of removal was 90%, algae removal was 95%, but it had a poor effect on bacteria removal with 27% removal due to adsorption of residual chlorine by GAC. The study recommended replacing mono media by dual media filter to improve water quality where the GAC was efficient to remove trihalomethanes in which the relative concentration (C/Co) was 0.16. The benefit cost calculated on 30 cm depth of GAC is equal to 0.04 piaster/m(3). In addition, it resulted in longer filter run of 54 hrs compared to average filter run of 24 hr for Czech filters, as well as increased water productivity where unit filter run volume was 324 m(3)/m(2) instead of 144 m(3)/m(2) for Czech mono media.

  13. Mechanisms of granular activated carbon anaerobic fluidized-bed process for treating phenols wastewater.

    PubMed

    Lao, Shan-gen

    2002-01-01

    Granular activated carbon (GAC) anaerobic fluidized-bed reactor was applied to treating phenols wastewater. When influent phenol concentration was 1000 mg/L, volume loadings of phenol and CODCr were 0.39 kg/(m3.d) and 0.98 kg/(m3.d), their removal rates were 99.9% and 96.4% respectively. From analyzing above results, the main mechanisms of the process are that through fluidizing GAC, its adsorption is combined with biodegradation, both activities are brought into full play, and phenol in wastewater is effectively decomposed. Meanwhile problems concerning gas-liquid separation and medium plugging are well solved. PMID:11887310

  14. A gacS Deletion in Pseudomonas aeruginosa Cystic Fibrosis Isolate CHA Shapes Its Virulence

    PubMed Central

    Sall, Khady Mayebine; Casabona, Maria Guillermina; Bordi, Christophe; Huber, Philippe; de Bentzmann, Sophie; Attrée, Ina; Elsen, Sylvie

    2014-01-01

    Pseudomonas aeruginosa, a human opportunistic pathogen, is capable of provoking acute and chronic infections that are associated with defined sets of virulence factors. During chronic infections, the bacterium accumulates mutations that silence some and activate other genes. Here we show that the cystic fibrosis isolate CHA exhibits a unique virulence phenotype featuring a mucoid morphology, an active Type III Secretion System (T3SS, hallmark of acute infections), and no Type VI Secretion System (H1-T6SS). This virulence profile is due to a 426 bp deletion in the 3′ end of the gacS gene encoding an essential regulatory protein. The absence of GacS disturbs the Gac/Rsm pathway leading to depletion of the small regulatory RNAs RsmY/RsmZ and, in consequence, to expression of T3SS, while switching off the expression of H1-T6SS and Pel polysaccharides. The CHA isolate also exhibits full ability to swim and twitch, due to active flagellum and Type IVa pili. Thus, unlike the classical scheme of balance between virulence factors, clinical strains may adapt to a local niche by expressing both alginate exopolysaccharide, a hallmark of membrane stress that protects from antibiotic action, host defences and phagocytosis, and efficient T3S machinery that is considered as an aggressive virulence factor. PMID:24780952

  15. Application of the biological granular activated carbon fluidized bed reactor process for gas industry waste treatment. Topical report, January 1991-December 1992

    SciTech Connect

    Wagner, D.; Sunday, A.; Hickey, R.F.

    1993-06-01

    The research and development work is focused on evaluating the applicability of using the biological granular activated carbon-fluidized bed reactor (GAC-FBR) for helping to solve gas industry waste treatment needs. The specific goals are to use and modify the GAC-FBR process, as needed, for (1) remediation of groundwater contaminated by gas industry operations, and (2) treatment of gas production and exploration waters.

  16. Oxyanion flux characterization using passive flux meters: development and field testing of surfactant-modified granular activated carbon.

    PubMed

    Lee, Jimi; Rao, P S C; Poyer, Irene C; Toole, Robyn M; Annable, M D; Hatfield, K

    2007-07-17

    We report here on the extension of Passive Flux Meter (PFM) applications for measuring fluxes of oxyanions in groundwater, and present results for laboratory and field studies. Granular activated carbon, with and without impregnated silver (GAC and SI-GAC, respectively), was modified with a cationic surfactant, hexadecyltrimethylammonium (HDTMA), to enhance the anion exchange capacity (AEC). Langmuir isotherm sorption maxima for oxyanions measured in batch experiments were in the following order: perchlorate>chromate>selenate, consistent with their selectivity. Linear sorption isotherms for several alcohols suggest that surfactant modification of GAC and SI-GAC reduced (approximately 30-45%) sorption of alcohols by GAC. Water and oxyanion fluxes (perchlorate and chromate) measured by deploying PFMs packed with surfactant-modified GAC (SM-GAC) or surfactant-modified, silver-impregnated GAC (SM-SI-GAC) in laboratory flow chambers were in close agreement with the imposed fluxes. The use of SM-SI-GAC as a PFM sorbent was evaluated at a field site with perchlorate contamination of a shallow unconfined aquifer. PFMs packed with SM-SI-GAC were deployed in three existing monitoring wells with a perchlorate concentration range of approximately 2.5 to 190 mg/L. PFM-measured, depth-averaged, groundwater fluxes ranged from 1.8 to 7.6 cm/day, while depth-averaged perchlorate fluxes varied from 0.22 to 1.7 g/m2/day. Groundwater and perchlorate flux distributions measured in two PFM deployments closely matched each other. Depth-averaged Darcy fluxes measured with PFMs were in line with an estimate from a borehole dilution test, but much smaller than those based on hydraulic conductivity and head gradients; this is likely due to flow divergence caused by well-screen clogging. Flux-averaged perchlorate concentrations measured with PFM deployments matched concentrations in groundwater samples taken from one well, but not in two other wells, pointing to the need for additional field

  17. Oxyanion flux characterization using passive flux meters: Development and field testing of surfactant-modified granular activated carbon

    NASA Astrophysics Data System (ADS)

    Lee, Jimi; Rao, P. S. C.; Poyer, Irene C.; Toole, Robyn M.; Annable, M. D.; Hatfield, K.

    2007-07-01

    We report here on the extension of Passive Flux Meter (PFM) applications for measuring fluxes of oxyanions in groundwater, and present results for laboratory and field studies. Granular activated carbon, with and without impregnated silver (GAC and SI-GAC, respectively), was modified with a cationic surfactant, hexadecyltrimethylammonium (HDTMA), to enhance the anion exchange capacity (AEC). Langmuir isotherm sorption maxima for oxyanions measured in batch experiments were in the following order: perchlorate >> chromate > selenate, consistent with their selectivity. Linear sorption isotherms for several alcohols suggest that surfactant modification of GAC and SI-GAC reduced (˜ 30-45%) sorption of alcohols by GAC. Water and oxyanion fluxes (perchlorate and chromate) measured by deploying PFMs packed with surfactant-modified GAC (SM-GAC) or surfactant-modified, silver-impregnated GAC (SM-SI-GAC) in laboratory flow chambers were in close agreement with the imposed fluxes. The use of SM-SI-GAC as a PFM sorbent was evaluated at a field site with perchlorate contamination of a shallow unconfined aquifer. PFMs packed with SM-SI-GAC were deployed in three existing monitoring wells with a perchlorate concentration range of ˜ 2.5 to 190 mg/L. PFM-measured, depth-averaged, groundwater fluxes ranged from 1.8 to 7.6 cm/day, while depth-averaged perchlorate fluxes varied from 0.22 to 1.7 g/m 2/day. Groundwater and perchlorate flux distributions measured in two PFM deployments closely matched each other. Depth-averaged Darcy fluxes measured with PFMs were in line with an estimate from a borehole dilution test, but much smaller than those based on hydraulic conductivity and head gradients; this is likely due to flow divergence caused by well-screen clogging. Flux-averaged perchlorate concentrations measured with PFM deployments matched concentrations in groundwater samples taken from one well, but not in two other wells, pointing to the need for additional field testing. Use of

  18. Fenton-Driven Chemical Regeneration of MTBE-Spent Granular Activated Carbon -- A Pilot Study

    EPA Science Inventory

    MTBE-spent granular activated carbon (GAC) underwent 3 adsorption/oxidation cycles. Pilot-scale columns were intermittently placed on-line at a ground water pump and treat facility, saturated with MTBE, and regenerated with H2O2 under different chemical, physical, and operational...

  19. Remediation of ground water containing chlorinated and brominated hydrocarbons, benzene and chromate by sequential treatment using ZVI and GAC

    NASA Astrophysics Data System (ADS)

    Plagentz, Volkmar; Ebert, Markus; Dahmke, Andreas

    2006-03-01

    A laboratory experiment with two sequenced columns was performed as a preliminary study for the installation of a permeable reactive barrier (PRB) at a site where a mixed ground water contamination exists. The first column contained granular zero valent iron (ZVI), the second column was filled with granular activated carbon (GAC). Trichloromethane (TCM, 930 μg/l) and chlorobenzene (MCB, 260 μg/l) were added to the ground water from the site as the main contaminants. Smaller amounts (<60 μg/l) of benzene, 1,2-dichloroethane, 1,1,2-trichloroethane (1,1,2-TCA), 1,1-dichloroethene (1,1-DCE), trichloroethene (TCE), tetrachloroethene (PCE), 1,2-dichloropropane (1,2-DCP), bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM), vinyl chloride and chromate were also added to the water to simulate the complex contamination pattern at the site of interest. PCE, TCE, 1,1-DCE, DBCM, BDCM, TBM, MCB and chromate were remediated in contact with ZVI, while the remaining contaminants showed incomplete degradation. A fraction of 8 16.5% TCM was converted to dichloromethane (DCM). Remaining contaminant concentrations were efficiently sorbed by the GAC until breakthrough of DCM was observed after 1,230 exchanged pore volumes in the GAC. The results show that the complex mixture of contaminants can be remediated by a sequenced PRB consisting of ZVI and GAC and that DCM sorption capacity is the critical parameter for the dimensions of the GAC reactor.

  20. Treatment of PAHs in waters using the GAC-FBR process

    SciTech Connect

    Hickey, R.F.; Sunday, A.; Wagner, D.; Groshko, V.; Rajan, R.V.; Leuschner, A.; Hayes, T.D.

    1995-12-31

    Pilot studies were conducted to determine the utility of the granular activated carbon fluidized-bed reactor (GAC-FBR) process to treat groundwater from manufactured gas plant (MGP) sites containing polycyclic aromatic hydrocarbons (PAHs) and a process effluent water from a deep subsurface dense, nonaqueous-phase liquid (DNAPL) removal process at an MGP site. Removal of naphthalene exceeded 99.9%, and overall PAH removals of 99+% were observed at organic loading rates (OLRs) exceeding 4-kg chemical oxygen demand (COD)/m{sup 3}-d and a hydraulic retention time (HRT) of about 6 min. Analysis of PAHs accumulated on GAC and oxygen consumption clearly demonstrated that removal of 2- to 4-ring PAHs was due primarily to biological oxidation and not to adsorption. Analysis of influent and effluent samples using Microtox{reg_sign} indicated removal of toxicity. Full-scale application of the GAC-FBR process has begun at a Superfund site in Pennsylvania. The GAC-FBR is being used to treat a 15-gal per min (gpm) process effluent flow from a subsurface DNAPL removal process. Initial results confirm the ability of the process to treat PAHs at high OLRs and short HRTs.

  1. Adsorption of N-nitrosodimethylamine precursors by powdered and granular activated carbon.

    PubMed

    Hanigan, David; Zhang, Jinwei; Herckes, Pierre; Krasner, Stuart W; Chen, Chao; Westerhoff, Paul

    2012-11-20

    Activated carbon (AC) has been shown to remove precursors of halogenated disinfection byproducts. Granular and powdered activated carbon (GAC, PAC) were investigated for their potential to adsorb N-nitrosodimethylamine (NDMA) precursors from blends of river water and effluent from a wastewater treatment plant (WWTP). At bench scale, waters were exposed to lignite or bituminous AC, either as PAC in bottle point experiments or as GAC in rapid small-scale column tests (RSSCTs). NDMA formation potential (FP) was used as a surrogate for precursor removal. NDMA FP was reduced by 37, 59, and 91% with 3, 8, and 75 mg/L of one PAC, respectively, with a 4-h contact time. In RSSCTs and in full-scale GAC contactors, NDMA FP removal always exceeded that of the bulk dissolved organic carbon (DOC) and UV absorbance at 254 nm. For example, whereas DOC breakthrough exceeded 90% of its influent concentration after 10,000 bed volumes of operation in an RSSCT, NDMA FP was less than 40% of influent concentration after the same bed life of the GAC. At full or pilot scale, high NDMA FP reduction ranging from >60 to >90% was achieved across GAC contactors, dependent upon the GAC bed life and/or use of a preoxidant (chlorine or ozone). In all experiments, NDMA formation was not reduced to zero, which suggests that although some precursors are strongly sorbed, others are not. This is among the first studies to show that AC is capable of adsorbing NDMA precursors, but further research is needed to better understand NDMA precursor chemical properties (e.g., hydrophobicity, molecular size) and evaluate how best to incorporate this finding into full-scale designs and practice.

  2. Adsorption of N-nitrosodimethylamine precursors by powdered and granular activated carbon.

    PubMed

    Hanigan, David; Zhang, Jinwei; Herckes, Pierre; Krasner, Stuart W; Chen, Chao; Westerhoff, Paul

    2012-11-20

    Activated carbon (AC) has been shown to remove precursors of halogenated disinfection byproducts. Granular and powdered activated carbon (GAC, PAC) were investigated for their potential to adsorb N-nitrosodimethylamine (NDMA) precursors from blends of river water and effluent from a wastewater treatment plant (WWTP). At bench scale, waters were exposed to lignite or bituminous AC, either as PAC in bottle point experiments or as GAC in rapid small-scale column tests (RSSCTs). NDMA formation potential (FP) was used as a surrogate for precursor removal. NDMA FP was reduced by 37, 59, and 91% with 3, 8, and 75 mg/L of one PAC, respectively, with a 4-h contact time. In RSSCTs and in full-scale GAC contactors, NDMA FP removal always exceeded that of the bulk dissolved organic carbon (DOC) and UV absorbance at 254 nm. For example, whereas DOC breakthrough exceeded 90% of its influent concentration after 10,000 bed volumes of operation in an RSSCT, NDMA FP was less than 40% of influent concentration after the same bed life of the GAC. At full or pilot scale, high NDMA FP reduction ranging from >60 to >90% was achieved across GAC contactors, dependent upon the GAC bed life and/or use of a preoxidant (chlorine or ozone). In all experiments, NDMA formation was not reduced to zero, which suggests that although some precursors are strongly sorbed, others are not. This is among the first studies to show that AC is capable of adsorbing NDMA precursors, but further research is needed to better understand NDMA precursor chemical properties (e.g., hydrophobicity, molecular size) and evaluate how best to incorporate this finding into full-scale designs and practice. PMID:23106335

  3. Nanofiltration and granular activated carbon treatment of perfluoroalkyl acids.

    PubMed

    Appleman, Timothy D; Dickenson, Eric R V; Bellona, Christopher; Higgins, Christopher P

    2013-09-15

    Perfluoroalkyl acids (PFAAs) are of concern because of their persistence in the environment and the potential toxicological effects on humans exposed to PFAAs through a variety of possible exposure routes, including contaminated drinking water. This study evaluated the efficacy of nanofiltration (NF) and granular activated carbon (GAC) adsorption in removing a suite of PFAAs from water. Virgin flat-sheet NF membranes (NF270, Dow/Filmtec) were tested at permeate fluxes of 17-75 Lm(-2)h(-1) using deionized (DI) water and artificial groundwater. The effects of membrane fouling by humic acid on PFAA rejection were also tested under constant permeate flux conditions. Both virgin and fouled NF270 membranes demonstrated >93% removal for all PFAAs under all conditions tested. GAC efficacy was tested using rapid small-scale columns packed with Calgon Filtrasorb300 (F300) carbon and DI water with and without dissolved organic matter (DOM). DOM effects were also evaluated with F600 and Siemens AquaCarb1240C. The F300 GAC had <20% breakthrough of all PFAAs in DI water for up to 125,000 bed volumes (BVs). When DOM was present, >20% breakthrough of all PFAAs by 10,000 BVs was observed for all carbons.

  4. Electron shuttle-mediated biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine adsorbed to granular activated carbon.

    PubMed

    Millerick, Kayleigh; Drew, Scott R; Finneran, Kevin T

    2013-08-01

    Granular activated carbon (GAC) effectively removes hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from groundwater but generates RDX-laden GAC that must be disposed of or regenerated. Batch reactors containing GAC to which RDX was preadsorbed were used in experiments to test the potential for adsorbed RDX reduction and daughter product formation using (i) chemically reduced anthrahydroquinone-2,6-disulfonate (AH2QDS), (ii) resting Geobacter metallireducens strain GS-15, and (iii) a combined system containing AQDS and GS-15. Approximately 97.0% of the adsorbed RDX was transformed in each of these experimental systems by 90 h. Chemically reduced AQDS (AH2QDS) transformed 99.2% of adsorbed RDX; formaldehyde was produced rapidly and was stoichiometric (3 mol HCHO per mol RDX). Geobacter metallireducens also reduced RDX with and without AQDS present. This is the first study to demonstrate biological transformation of RDX adsorbed to GAC. Formaldehyde increased and then decreased in biological systems, suggesting a previously unreported capacity for G. metallireducens to oxidize formaldehyde, which was confirmed with resting cell suspensions. These data suggest the masses of GAC waste currently produced by activated carbon at RDX remediation sites can be minimized, decreasing the carbon footprint of the treatment technology. Alternatively, this strategy may be used to develop a Bio-GAC system for ex situ RDX treatment. PMID:23837558

  5. Electron shuttle-mediated biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine adsorbed to granular activated carbon.

    PubMed

    Millerick, Kayleigh; Drew, Scott R; Finneran, Kevin T

    2013-08-01

    Granular activated carbon (GAC) effectively removes hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from groundwater but generates RDX-laden GAC that must be disposed of or regenerated. Batch reactors containing GAC to which RDX was preadsorbed were used in experiments to test the potential for adsorbed RDX reduction and daughter product formation using (i) chemically reduced anthrahydroquinone-2,6-disulfonate (AH2QDS), (ii) resting Geobacter metallireducens strain GS-15, and (iii) a combined system containing AQDS and GS-15. Approximately 97.0% of the adsorbed RDX was transformed in each of these experimental systems by 90 h. Chemically reduced AQDS (AH2QDS) transformed 99.2% of adsorbed RDX; formaldehyde was produced rapidly and was stoichiometric (3 mol HCHO per mol RDX). Geobacter metallireducens also reduced RDX with and without AQDS present. This is the first study to demonstrate biological transformation of RDX adsorbed to GAC. Formaldehyde increased and then decreased in biological systems, suggesting a previously unreported capacity for G. metallireducens to oxidize formaldehyde, which was confirmed with resting cell suspensions. These data suggest the masses of GAC waste currently produced by activated carbon at RDX remediation sites can be minimized, decreasing the carbon footprint of the treatment technology. Alternatively, this strategy may be used to develop a Bio-GAC system for ex situ RDX treatment.

  6. Degradation kinetics and mechanism of trace nitrobenzene by granular activated carbon enhanced microwave/hydrogen peroxide system.

    PubMed

    Tan, Dina; Zeng, Honghu; Liu, Jie; Yu, Xiaozhang; Liang, Yanpeng; Lu, Lanjing

    2013-07-01

    The kinetics of the degradation of trace nitrobenzene (NB) by a granular activated carbon (GAC) enhanced microwave (MW)/hydrogen peroxide (H202) system was studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiency were examined. It was found that the reaction rate fits well to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced the degradation rate of NB in water. Under a given condition (MW power 300 W, H202 dosage 10 mg/L, pH 6.85 and temperature (60 +/- 5)degrees C), the degradation rate of NB was 0.05214 min-1when 4 g/L GAC was added. In general, alkaline pH was better for NB degradation; however, the optimum pH was 8.0 in the tested pH value range of 4.0-12.0. At H202 dosage of 10 mg/L and GAC dosage of 4 g/L, the removal of NB was decreased with increasing initial concentrations of NB, indicating that a low initial concentration was beneficial for the degradation of NB. These results indicated that the MW/GAC/H202 process was effective for trace NB degradation in water. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction and dehydrogenation reaction enhanced NB degradation. PMID:24218864

  7. Full- and pilot-scale GAC adsorption of organic micropollutants.

    PubMed

    Kennedy, Anthony M; Reinert, Allison M; Knappe, Detlef R U; Ferrer, Imma; Summers, R Scott

    2015-01-01

    Granular activated carbon (GAC) adsorption of 30 environmentally relevant micropollutants (MP) from four surface waters was investigated at the pilot-scale with empty bed contact times (EBCTs) of 7 and 15 min. An increase in background dissolved organic matter resulted in more and earlier MP breakthrough. Compared to an EBCT of 7 min, MP breakthrough at an EBCT of 15 min demonstrated 52% later breakthrough on average for five MPs on a throughput basis. A regression model was developed with data from three waters to predict MP throughput in bed volumes to 10% breakthrough (BV10%) based on the influent dissolved organic carbon concentration and the MP pH-dependent octanol-water partition coefficient, polarizability, and molecular volume. The regression model over predicted full-scale BV10% values when applied to a wastewater-water impacted water source and to GAC with a larger particle diameter, for which a particle size adjustment was able to account for most of the difference. PMID:25462732

  8. Utilization of granular activated carbon adsorber for nitrates removal from groundwater of the Cluj region.

    PubMed

    Moşneag, Silvia C; Popescu, Violeta; Dinescu, Adrian; Borodi, George

    2013-01-01

    The level of nitrates from groundwater from Cluj County and other areas from Romania have increased values, exceeding or getting close to the allowed limit values, putting in danger human and animal heath. In this study we used granular activated carbon adsorbent (GAC) for nitrate (NO(-)3) removal for the production of drinking water from groundwater of the Cluj county. The influences of the contact time, nitrate initial concentration, and adsorbent concentration have been studied. We determined the equilibrium adsorption capacity of GAC, used for NO(-)3 removal and we applied the Langmuir and Freundlich isotherm models. Ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, X ray diffraction (XRD), Scanning Electron Microscopy (SEM) were used for process characterization. We also determined: pH, conductivity, Total Dissolved Solids and Total Hardness. The GAC adsorbents have excellent capacities of removing nitrate from groundwater from Cluj County areas.

  9. Catalytic ozonation of pentachlorophenol in aqueous solutions using granular activated carbon

    NASA Astrophysics Data System (ADS)

    Asgari, Ghorban; Samiee, Fateme; Ahmadian, Mohammad; Poormohammadi, Ali; solimanzadeh, Bahman

    2014-11-01

    The efficiency of granular activated carbon (GAC) was investigated in this study as a catalyst for the elimination of pentachlorophenol (PCP) from contaminated streams in a laboratory-scale semi-batch reactor. The influence of important parameters including solution pH (2-10), radical scavenger (tert-butanol, 0.04 mol/L), catalyst dosage (0.416-8.33 g/L), initial PCP concentration (100-1000 mg/L) and ozone flow rate (2.3-12 mg/min) was examined on the efficiency of the catalytic ozonation process (COP) in degradation and mineralization of PCP in aqueous solution. The experimental results showed that catalytic ozonation with GAC was most effective at pH of 8 with ozone flow rate of 12 mg/min and a GAC dosage of 2 g. Compared to the sole ozonation process (SOP), the removal levels of PCP and COP were, 98, and 79 %, respectively. The degradation rate of kinetics was also investigated. The results showed that using a GAC catalyst in the ozonation of PCP produced an 8.33-fold increase in rate kinetic compared to the SOP under optimum conditions. Tert-butanol alcohol (TBA) was used as a radical scavenger. The results demonstrated that COP was affected less by TBA than by SOP. These findings suggested that GAC acts as a suitable catalyst in COP to remove refractory pollutants from aqueous solution.

  10. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

    USGS Publications Warehouse

    Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

    2016-01-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

  11. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon.

    PubMed

    Lewis, Ariel S; Huntington, Thomas G; Marvin-DiPasquale, Mark C; Amirbahman, Aria

    2016-05-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

  12. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction.

    PubMed

    Yu, Zirui; Peldszus, Sigrid; Huck, Peter M

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs)-naproxen and carbamazepine and one endocrine disrupting compound (EDC)-nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. PMID:19350922

  13. Optimisation and significance of ATP analysis for measuring active biomass in granular activated carbon filters used in water treatment.

    PubMed

    Magic-Knezev, Aleksandra; van der Kooij, Dick

    2004-11-01

    A method for determining the concentration of active microbial biomass in granular activated carbon (GAC) filters used in water treatment was developed to facilitate studies on the interactions between adsorption processes and biological activity in such filters. High-energy sonication at a power input of 40 W was applied to GAC samples for the detachment of biomass which was measured as adenosine triphosphate (ATP). Modelling of biomass removal indicated that a series of six to eight sonication treatments of 2 min each yielded more than 90% of the attached active biomass. The ATP concentrations in 30 different GAC filters at nine treatment plants in The Netherlands ranged from 25 to 5000 ng ATP cm(-3) GAC, with the highest concentrations at long filter run times and pretreatment with ozone. A similar concentration range was observed in nine rapid sand (RS) filters. ATP concentrations correlated significantly (p<0.05) with total direct bacterial cell counts in each of these filter types, but the median value of the ATP content per cell in GAC filters (2.1 x 10(-8) ng ATP/cell) was much lower than in the RS filters (3.6 x 10(-7) ng ATP/cell). Average biofilm concentrations ranging from 500 to 10(5) pg ATP cm(-2) were calculated assuming spherical shapes for the GAC particles but values were about 20 times lower when the surface of pores >1 microm diameter is included in these calculations. The quantitative biomass analysis with ATP enables direct comparisons with biofilm concentrations reported for spiral wound membranes used in water treatment, for distribution system pipes and other aquatic environments.

  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. 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

  16. Equilibrium model for biodegradation and adsorption of mixtures in GAC columns

    SciTech Connect

    Erlanson, B.C.; Dvorak, B.I.; Speitel, G.E. Jr.; Lawler, D.F.

    1997-05-01

    Microbial activity in granular activated carbon (GAC) columns has received much attention over the last 15 years because biodegradation of one or more chemicals might increase the GAC service life, thereby decreasing costs. An equilibrium model for simultaneous biodegradation and adsorption was developed and verified with existing data. For simplicity the model was restricted to only two components: one biodegradable and one not. The results from modeling over 300 hypothetical situations identified conditions where biodegradation significantly extends the service life of granular activated carbon (GAC) columns. When the nonbiodegradable chemical controls the service life, the only significant gains in service life occurred when the biodegradable and nonbiodegradable chemical had similar adsorbabilities. When the biodegradable chemical controls the service life, the service life was 1.2--7 times that with adsorption alone, depending on the relative adsorbability of the two chemicals. The increase in service life can be maximized by ensuring that biodegradation begins as soon as possible after start-up. The model provides a good screening tool for initial assessments of process feasibility, preliminary economic analyses, and planning of detailed experimental and computer modeling studies. Examples are presented using benzene and TCE to illustrate how the general trends presented apply to specific cases.

  17. Controlling Instability in gacS-gacA Regulatory Genes during Inoculant Production of Pseudomonas fluorescens Biocontrol Strains

    PubMed Central

    Duffy, Brion K.; Défago, Geneviève

    2000-01-01

    Secondary metabolism in fluorescent pseudomonads is globally regulated by gacS, which encodes a membrane-bound sensor kinase, and gacA, which encodes a transcriptional response regulator. Spontaneous mutation in either gene blocked biosynthesis of the antimicrobial compounds hydrogen cyanide, 2,4-diacetylphloroglucinol, pyoluteorin, and pyrrolnitrin by the model biocontrol strain Pseudomonas fluorescens CHA0. Spontaneous mutants also had altered abilities to utilize several carbon sources and to increase medium pH compared with the wild type, suggesting that gacS and gacA influence primary as well as secondary bacterial metabolism. Inoculant efficacy for biocontrol was significantly reduced by contamination with regulatory mutants which accumulated during inoculum production. Spontaneous mutants accumulated in all 192 separate liquid cultures examined, typically at a frequency of 1% or higher after 12 days. During scale-up in a simulated industrial fermentation process, mutants increased exponentially and accounted for 7, 23, and 61% of the total viable cells after transfer to 20-, 100-, and 500-ml preparations, respectively. GacS− and GacA− mutants had identical phenotypes and occurred at the same frequency, indicating that the selective pressures for the two mutants were similar. We developed a simple screening method for monitoring inoculant quality based on the distinctive appearance of mutant colonies (i.e., orange color, enlarged diameter, hyperfluorescence). Mutant competitiveness was favored in a nutrient-rich medium with a high electrolyte concentration (nutrient broth containing yeast extract). We were able to control mutant accumulation and to clean up contaminated cultures by using certain mineral amendments (i.e., zinc, copper, cobalt, manganese, and ammonium molybdate) or by diluting media 1/10. Spontaneous mutants and genetic constructs had the same response to culture conditions. Zinc and medium dilution were also effective for improving the

  18. ORC-GAC-Fe0 system for the remediation of trichloroethylene and monochlorobenzene contaminated aquifer: 1. Adsorption and degradation.

    PubMed

    Lin, Qi; Chen, Ying-xu; Plagentz, V; Schäfer, D; Dahmke, A

    2004-01-01

    Activities at a former Chemistry Triangle in Bitterfeld, Germany, resulted in contamination of groundwater with a mixture of trichloroethylene(TCE) and monochlorobenzene(MCB). The objective of this study was to develop a barrier system, which includes an ORC(oxygen release compounds) and GAC(granular activated carbon) layer for adsorption of MCB and bioregeneration of GAC, a Fe0 layer for chemical reductive dechlorination of TCE and other chlorinated hydrocarbon in situ. A laboratory-scale column experiment was conducted to evaluate the feasibility of this proposed system. This experiment was performed using a series of continuous flow Teflon columns including an ORC column, a GAC column, and a Fe0 column. Simulated MCB and TCE contaminated groundwater was pumped upflow into this system at a flow rate of 1.1 ml/min. Results showed that 17%-50% of TCE and 28%-50% of MCB were dissipated in ORC column. Chloride ion, however, was not released, which suggest the dechlorination do not happen in ORC column. In GAC column, the adsorption of contaminants on activated carbon and their induced degradation by adapted microorganisms attached to the carbon surface were observed. Due to competitive exchange processes, TCE can be desorbed by MCB in GAC column and further degraded in iron column. The completely dechlorination rate of TCE was 0.16-0.18 cm(-1), 1-4 magnitudes more than the formation rate of three dichloroethene isomers. Cis-DCE is the main chlorinated product, which can be cumulated in the system, not only depending on the formation rate and its decaying rate, but also the initial concentration of TCE.

  19. A GacS deficiency does not affect Pseudomonas chlororaphis PA23 fitness when growing on canola, in aged batch culture or as a biofilm.

    PubMed

    Poritsanos, N; Selin, C; Fernando, W G D; Nakkeeran, S; de Kievit, T R

    2006-12-01

    Pseudomonas chlororaphis PA23 is a biocontrol agent that protects against the fungal pathogen Sclerotinia sclerotiorum. Employing transposon mutagenesis, we isolated a gacS mutant that no longer exhibited antifungal activity. Pseudomonas chlororaphis PA23 was previously reported to produce the nonvolatile antibiotics phenazine 1-carboxylic acid and 2-hydroxyphenazine. We report here that PA23 produces additional compounds, including protease, lipase, hydrogen cyanide, and siderophores, that may contribute to its biocontrol ability. In the gacS mutant background, generation of these products was markedly reduced or delayed with the exception of siderophores, which were elevated. Not surprisingly, this mutant was unable to protect canola from disease incited by S. sclerotiorum. The gacS mutant was able to sustain itself in the canola phyllosphere, therefore, the loss of biocontrol activity can be attributed to a reduced production of antifungal compounds and not a declining population size. Competition assays between the mutant and wild type revealed equivalent fitness in aged batch culture; consequently, the gacS mutation did not impart a growth advantage in the stationary phase phenotype. Under minimal nutrient conditions, the gacS-deficient strain produced a tenfold less biofilm than the wild type. However, no difference was observed in the ability of the mutant biofilm to protect cells from lethal antibiotic challenge. PMID:17473887

  20. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  1. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  2. Passivation process and the mechanism of packing particles in the Fe0/GAC system during the treatment of ABS resin wastewater.

    PubMed

    Lai, Bo; Zhou, Yuexi; Wang, Juling; Zhang, Yunhong; Chen, Zhiqiang

    2014-01-01

    This study provides mechanistic insights into the passivation of the packing particles during the treatment of acrylonitrile-butadiene-styrene (ABS) resin wastewater by the Fe0/GAC system. The granular-activated carbon (GAC) and iron chippings (Fe0) were mixed together with a volumetric ratio of 1:1. GAC has a mean particle size of approximately 3-5 mm, a specific surface of 748 m2 g(-1), a total pore volume of 0.48 mL g(-1) and a bulk density of 0.49 g cm(-3). The iron chippings have a compact and non-porous surface morphology. The results show that the packing particles in the Fe0/GAC system would lose their activity because the removal of TOC and PO4(3-) for ABS resin wastewater could not carried out by the Fe0/GAC system after 40 days continuous running. Meanwhile, the availability of O2 and intrinsic reactivity of Fe0 play a key role on the form of passive film with different iron oxidation states. The passive film on the surface of iron chippings was formed by two phases: (a) local corrosion phase (0-20 d) and (b) co-precipitation phase (20-40 d), while that of GAC was mainly formed by the co-precipitation of corrosion products with SO4(2-) and PO4(3-) because SO4(2-) and PO4(3-) would not easily reach the Fe0 surface. Therefore, in order to avoid the occurrence of filler passivation, high concentrations of SO4(2-) and PO4(3-) in wastewater should be removed before the treatment process of the Fe/GAC system.

  3. Role of GacA in virulence of Vibrio vulnificus.

    PubMed

    Gauthier, Julie D; Jones, Melissa K; Thiaville, Patrick; Joseph, Jennifer L; Swain, Rick A; Krediet, Cory J; Gulig, Paul A; Teplitski, Max; Wright, Anita C

    2010-12-01

    The GacS/GacA two-component signal transduction system regulates virulence, biofilm formation and symbiosis in Vibrio species. The present study investigated this regulatory pathway in Vibrio vulnificus, a human pathogen that causes life-threatening disease associated with the consumption of raw oysters and wound infections. Small non-coding RNAs (csrB1, csrB2, csrB3 and csrC) commonly regulated by the GacS/GacA pathway were decreased (P<0.0003) in a V. vulnificus CMCP6 ΔgacA : : aph mutant compared with the wild-type parent, and expression was restored by complementation of the gacA deletion mutation in trans. Of the 20 genes examined by RT-PCR, significant reductions in the transcript levels of the mutant in comparison with the wild-type strain were observed only for genes related to motility (flaA), stationary phase (rpoS) and protease (vvpE) (P=0.04, 0.01 and 0.002, respectively). Swimming motility, flagellation and opaque colony morphology indicative of capsular polysaccharide (CPS) were unchanged in the mutant, while cytotoxicity, protease activity, CPS phase variation and the ability to acquire iron were decreased compared with the wild-type (P<0.01). The role of gacA in virulence of V. vulnificus was also demonstrated by significant impairment in the ability of the mutant strain to cause either skin (P<0.0005) or systemic infections (P<0.02) in subcutaneously inoculated, non-iron-treated mice. However, the virulence of the mutant was equivalent to that of the wild-type in iron-treated mice, demonstrating that the GacA pathway in V. vulnificus regulates the virulence of this organism in an iron-dependent manner.

  4. Seasonal changes in the invertebrate community of granular activated carbon filters and control technologies.

    PubMed

    Wang, Qing; You, Wei; Li, Xiaowei; Yang, Yufeng; Liu, Lijun

    2014-03-15

    Invertebrate colonization of granular activated carbon (GAC) filters in the waterworks is one of the most frequently occurring and least studied biological problems of water processing in China. A survey of invertebrate colonization of GAC filters was carried out weekly from October 2010 to December 2011 at a reservoir water treatment works in South China. Twenty-six kinds of invertebrates were observed. The abundance was as high as 5600ind.m(-3) with a mean of 860ind.m(-3). Large variations in abundance were observed among different seasons and before and after GAC filtration. The dominant organisms were rotifers and copepods. The average invertebrate abundance in the filtrate was 12-18.7 times of that in the pre-filtered water. Results showed that the GAC filters were colonized by invertebrates which may lead to a higher output of organisms in the filtrate than in the pre-filtered water. The invertebrate abundance in the GAC filters was statistically correlated with the water temperature. Seasonal patterns were observed. The invertebrate abundance grew faster in the spring and summer. Copepods were dominant in the summer while rotifers dominated in all other seasons of the year. There was a transition of small invertebrates (rotifers) gradually being substituted by larger invertebrates (copepods) from spring to summer. Control measures such as backwashing with chloric water, drying filter beds and soaking with saliferous water were implemented in the waterworks to reduce invertebrate abundances in the GAC filters. The results showed that soaking with saliferous water (99%, reduction in percent) was best but drying the filter beds (84%) was more economical. Soaking filter beds with 20g/L saliferous water for one day can be implemented in case of emergency. In order to keep invertebrate abundance in the acceptable range, some of these measures should be adopted.

  5. Granular biochar compared with activated carbon for wastewater treatment and resource recovery.

    PubMed

    Huggins, Tyler M; Haeger, Alexander; Biffinger, Justin C; Ren, Zhiyong Jason

    2016-05-01

    Granular wood-derived biochar (BC) was compared to granular activated carbon (GAC) for the treatment and nutrient recovery of real wastewater in both batch and column studies. Batch adsorption studies showed that BC material had a greater adsorption capacity at the high initial concentrations of total chemical oxygen demand (COD-T) (1200 mg L(-1)), PO4 (18 mg L(-1)), and NH4 (50 mg L(-1)) compared to GAC. Conversely the BC material showed a lower adsorption capacity for all concentrations of dissolved chemical oxygen demand (COD-D) and the lower concentrations of PO4 (5 mg L(-1)) and NH4 (10 mg L(-1)). Packed bed column studies showed similar average COD-T removal rate for BC with 0.27 ± 0.01 kg m(-3) d(-1) and GAC with 0.24 ± 0.01 kg m(-3) d(-1), but BC had nearly twice the average removal rate (0.41 ± 0.08 kg m(-3) d(-3)) compared to GAC during high COD-T concentrations (>500 mg L(-1)). Elemental analysis showed that both materials accumulated phosphorous during wastewater treatment (2.6 ± 0.4 g kg(-1) and 1.9 ± 0.1 g kg(-1) for BC and GAC respectively). They also contained high concentrations of other macronutrients (K, Ca, and Mg) and low concentrations of metals (As, Cd, Cr, Pb, Zn, and Cu). The good performance of BC is attributed to its macroporous structure compared with the microporous GAC. These favorable treatment data for high strength wastewater, coupled with additional life-cycle benefits, helps support the use of BC in packed bed column filters for enhanced wastewater treatment and nutrient recovery. PMID:26954576

  6. Abundance and diversity of ammonia-oxidizing archaea and bacteria on granular activated carbon and their fates during drinking water purification process.

    PubMed

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki; Takahashi, Kazuhiko

    2016-01-01

    Ammonia is a precursor to trichloramine, which causes an undesirable chlorinous odor. Granular activated carbon (GAC) filtration is used to biologically oxidize ammonia during drinking water purification; however, little information is available regarding the abundance and diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) associated with GAC. In addition, their sources and fates in water purification process remain unknown. In this study, six GAC samples were collected from five full-scale drinking water purification plants in Tokyo during summer and winter, and the abundance and community structure of AOA and AOB associated with GAC were studied in these two seasons. In summer, archaeal and bacterial amoA genes on GACs were present at 3.7 × 10(5)-3.9 × 10(8) gene copies/g-dry and 4.5 × 10(6)-4.2 × 10(8) gene copies/g-dry, respectively. In winter, archaeal amoA genes remained at the same level, while bacterial amoA genes decreased significantly for all GACs. No differences were observed in the community diversity of AOA and AOB from summer to winter. Phylogenetic analysis revealed high AOA diversity in group I.1a and group I.1b in raw water. Terminal-restriction fragment length polymorphism analysis of processed water samples revealed that AOA diversity decreased dramatically to only two OTUs in group I.1a after ozonation, which were identical to those detected on GAC. It suggests that ozonation plays an important role in determining AOA diversity on GAC. Further study on the cell-specific activity of AOA and AOB is necessary to understand their contributions to in situ nitrification performance.

  7. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  8. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  9. Activated carbon amendment for in-situ remediation

    NASA Astrophysics Data System (ADS)

    Elmquist, M.; Brändli, R.; Henriksen, T.; Hartnik, T.; Cornelissen, G.

    2009-04-01

    For the first time in Europe, a novel and innovative remediation technique is used in a field pilot study. This technique is amendment of the soil with two types of activated carbon (AC). Here, one pulverized AC (PAC, 50% < 15µm and 3% >150 µm) and one granular AC (GAC, 1.7-0.43 mm) is tested. The idea of this technique is that the added AC binds organic contaminants so strongly that they cannot be taken up in living organisms or transported to other environmental compartments. Laboratory studies with 2% (wt %) AC amendment to an urban soil reduced the freely dissolved pore water concentrations of PAH by 17% to 99% (Brändli et al. 2008). Several parameters such as dissolved organic carbon (DOC), K, NO2, NO3, NH4, PO4 and PAH, are being measured in this field study. Plant growth and earthworm bioaccumulation tests were also carried out during the summer months. DOC showed a 70% reduction between untreated soil and soil with PAC about one year after the amendment. In the soil mixed with GAC, a 55% reduction could be measured. For K, a 40% lowering value was observed for the soil with GAC compared to no affect for the soil with PAC. NH4 was reduced by 50% for both GAC and PAC amended soils compared to the untreated soil, whereas NO2 and NO3 increased with 2-4 times for the soil with GAC and no effect were seen for the soil with PAC. The freely dissolved PAH concentrations were reduced by 49-78% for the soil with GAC and 82-96% for the soil with PAC. The plant experiment showed best growth rate in the soil with GAC, followed by the untreated soil and least growth was measured on the PAC treated soil. The low growth rate seen in the soil with PAC may come from the fact that DOC and some other nutrients are also being sorbed to the PAC surface together with the organic pollutants and are thereby taken away from the biological cycle. Amendment of soil with AC remediates the soil from organic contaminants when these pollutants are sorbed to the AC surface. This is an

  10. Optimizing the industrial wastewater pretreatment by activated carbon and coagulation: effects of hydrophobicity/hydrophilicity and molecular weights of dissolved organics.

    PubMed

    Khan, M Hammad; Ha, Dong-Hwan; Jung, Jinyoung

    2013-01-01

    This study addresses industrial wastewater treatment to remove dissolved organic compounds (DOC) using Fenton and coagulation processes, followed by granular activated carbon (GAC), and powdered activated carbon (PAC) as a pretreatment before reverse osmosis (RO). The effects of the hydrophobic / hydrophilic fractions and the molecular weights (MW) of the organics on DOC removal were tested and used to optimize the combination process. The raw wastewater (RWW) had a dominant hydrophobic fraction, as determined by polymeric resins Amberlite XAD-4. High performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) results showed that MW of organics were 256, 172, 258, 146, 392, 321, 182, 373, 276, 365, 409 and 453 in increasing order of hydrophobicity. GAC had higher adsorption capacity and was more selective for hydrophobic DOC removal than PAC. The removal efficiency of DOC by PAC and GAC was decreased after Fenton treatment, which decreased the hydrophobic fraction. Coagulation with ferric chloride efficiently removed the non-ionic hydrophilic and anionic hydrophilic organics. The coagulant doses selected as a pretreatment before GAC were 2.1 and 15.5 mg Fe(III)/mg DOC. The effluent total organic carbon (TOC) trends were correlated with the hydrophobic and hydrophilic fractions by using a rapid small-scale column test (RSSCT) for GAC breakthrough with a scale down factor of 5. GAC preferentially adsorbed the hydrophobic and the cationic hydrophilic organics. The effluent TOC trend could be divided into four stages: maximum adsorption, hydrophobic stage, exhaustion, and biological. The TOC removal after the exhaustion stage was almost equal to the hydrophilic fraction of TOC. Therefore these results demonstrated that the combination of coagulation and GAC adsorption was a highly efficient process for reducing DOC.

  11. Optimizing the industrial wastewater pretreatment by activated carbon and coagulation: effects of hydrophobicity/hydrophilicity and molecular weights of dissolved organics.

    PubMed

    Khan, M Hammad; Ha, Dong-Hwan; Jung, Jinyoung

    2013-01-01

    This study addresses industrial wastewater treatment to remove dissolved organic compounds (DOC) using Fenton and coagulation processes, followed by granular activated carbon (GAC), and powdered activated carbon (PAC) as a pretreatment before reverse osmosis (RO). The effects of the hydrophobic / hydrophilic fractions and the molecular weights (MW) of the organics on DOC removal were tested and used to optimize the combination process. The raw wastewater (RWW) had a dominant hydrophobic fraction, as determined by polymeric resins Amberlite XAD-4. High performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) results showed that MW of organics were 256, 172, 258, 146, 392, 321, 182, 373, 276, 365, 409 and 453 in increasing order of hydrophobicity. GAC had higher adsorption capacity and was more selective for hydrophobic DOC removal than PAC. The removal efficiency of DOC by PAC and GAC was decreased after Fenton treatment, which decreased the hydrophobic fraction. Coagulation with ferric chloride efficiently removed the non-ionic hydrophilic and anionic hydrophilic organics. The coagulant doses selected as a pretreatment before GAC were 2.1 and 15.5 mg Fe(III)/mg DOC. The effluent total organic carbon (TOC) trends were correlated with the hydrophobic and hydrophilic fractions by using a rapid small-scale column test (RSSCT) for GAC breakthrough with a scale down factor of 5. GAC preferentially adsorbed the hydrophobic and the cationic hydrophilic organics. The effluent TOC trend could be divided into four stages: maximum adsorption, hydrophobic stage, exhaustion, and biological. The TOC removal after the exhaustion stage was almost equal to the hydrophilic fraction of TOC. Therefore these results demonstrated that the combination of coagulation and GAC adsorption was a highly efficient process for reducing DOC. PMID:23383639

  12. Heterogeneous adsorption behavior of landfill leachate on granular activated carbon revealed by fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC).

    PubMed

    Lee, Sonmin; Hur, Jin

    2016-04-01

    Heterogeneous adsorption behavior of landfill leachate on granular activated carbon (GAC) was investigated by fluorescence excitation-emission matrix (EEM) combined with parallel factor analysis (PARAFAC). The equilibrium adsorption of two leachates on GAC was well described by simple Langmuir and Freundlich isotherm models. More nonlinear isotherm and a slower adsorption rate were found for the leachate with the higher values of specific UV absorbance and humification index, suggesting that the leachate containing more aromatic content and condensed structures might have less accessible sites of GAC surface and a lower degree of diffusive adsorption. Such differences in the adsorption behavior were found even within the bulk leachate as revealed by the dissimilarity in the isotherm and kinetic model parameters between two identified PARAFAC components. For both leachates, terrestrial humic-like fluorescence (C1) component, which is likely associated with relatively large sized and condensed aromatic structures, exhibited a higher isotherm nonlinearity and a slower kinetic rate for GAC adsorption than microbial humic-like (C2) component. Our results were consistent with size exclusion effects, a well-known GAC adsorption mechanism. This study demonstrated the promising benefit of using EEM-PARAFAC for GAC adsorption processes of landfill leachate through fast monitoring of the influent and treated leachate, which can provide valuable information on optimizing treatment processes and predicting further environmental impacts of the treated effluent.

  13. Comparisons of kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide adsorption in aqueous solution with graphene oxide, zeolite and activated carbon

    NASA Astrophysics Data System (ADS)

    Chang, Shenteng; Lu, Chungsying; Lin, Kun-Yi Andrew

    2015-01-01

    Graphene oxide (GO), sodium Y-type zeolite (NaY) and granular activated carbon (GAC) are selected as adsorbents to study their kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide (TMAH) adsorption from water. The adsorption kinetics follows the pseudo-second-order rate law while the adsorption thermodynamics shows an exothermic reaction with GO and GAC but displays an endothermic reaction with NaY. The adsorbed TMAH can be readily desorbed from the surface of GO and NaY by 0.05 M NaCl solution. A comparative study on the cyclic TMAH adsorption with GO, NaY and GAC is also conducted and the results reveal that GO exhibits the greatest TMAH adsorption capacity as well as superior reversibility of TMAH adsorption over 10 cycles of adsorption and desorption process. These features indicate that GO is a promising and efficient adsorbent for TMAH removal in wastewater treatment.

  14. Treatment of gas industry wastes using the biological granular activated carbon fluidized bed reactor process. Annual report, August 1994

    SciTech Connect

    Hickey, R.; Wagner, D.; Sunday, A.; Heine, B.; Rajan, R.

    1994-08-01

    The Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) system is a high rate process that combines the advantages of biological and physical-chemical treatment in a single unit operation. The process is particularly well-suited to treatment of contaminants present in water and wastewater at relatively low concentrations. Process economics indicate the GAC-FBR can be extremely cost-effective compared to aqueous phase GAC adsorption and air stripping followed by vapor phase control. Accordingly, three field trials are scheduled for the next 18 months; one at a manufactured gas plant site (PAHs), one at a gas dehydration site (BTEX), and one to treat a chlorinated solvent (TCE) at a government installation.

  15. The evaluation of empty bed contact time on the biodegradation of pentachlorophenol using an anaerobic GAC fluidized bed

    SciTech Connect

    Wilson, G.J.; Khodadoust, A.P.; Suidan, M.T.; Wagner, J.A.; Brenner, R.C.

    1994-12-31

    The objective of this research is to evaluate the effects of decreasing the empty-bed contact time (EBCT) on pentachlorophenol and its intermediates utilizing an anaerobic granular activated carbon (GAC) fluidized bed. The bioreactor A was fed an 100 mg/l influent concentration of PCP. EBCTs of 1.167 to 0.292 days for reactor A resulted in a PCP reduction greater than 99%. In addition, an equimolar conversion of PCP to monochlorophenol was observed.

  16. Rapid small-scale column testing of granular activated carbon for organic micro-pollutant removal in treated domestic wastewater.

    PubMed

    Zietzschmann, F; Müller, J; Sperlich, A; Ruhl, A S; Meinel, F; Altmann, J; Jekel, M

    2014-01-01

    This study investigates the applicability of the rapid small-scale column test (RSSCT) concept for testing of granular activated carbon (GAC) for organic micro-pollutants (OMPs) removal from wastewater treatment plant (WWTP) effluent. The chosen experimental setup was checked using pure water, WWTP effluent, different GAC products, and variable hydrodynamic conditions with different flow velocities and differently sized GAC, as well as different empty bed contact times (EBCTs). The setup results in satisfying reproducibility and robustness. RSSCTs in combination with WWTP effluent are effective when comparing the OMP removal potentials of different GAC products and are a useful tool for the estimation of larger filters. Due to the potentially high competition between OMPs and bulk organics, breakthrough curves are likely to have unfavorable shapes when treating WWTP effluent. This effect can be counteracted by extending the EBCT. With respect to the strong competition observed in GAC treatment of WWTP effluent, the small organic acid and neutral substances are retained longer in the RSSCT filters and are likely to cause the majority of the observed adsorption competition with OMPs. PMID:25325553

  17. PAH-sequestration capacity of granular and powder activated carbon amendments in soil, and their effects on earthworms and plants.

    PubMed

    Jakob, Lena; Hartnik, Thomas; Henriksen, Thomas; Elmquist, Marie; Brändli, Rahel C; Hale, Sarah E; Cornelissen, Gerard

    2012-07-01

    A field lysimeter study was carried out to investigate whether the amendment of 2% powder and granular activated carbon (PAC and GAC) to a soil with moderate PAH contamination had an impact on the PAH bioaccumulation of earthworms and plants, since AC is known to be a strong sorbent for organic pollutants. Furthermore, secondary effects of AC on plants and earthworms were studied through growth and nutrient uptake, and survival and weight gain. Additionally, the effect of AC amendments on soil characteristics like pH, water holding capacity, and the water retention curve of the soil were investigated. Results show that the amendment of 2% PAC had a negative effect on plant growth while the GAC increased the growth rate of plants. PAC was toxic to earthworms, demonstrated by a significant weight loss, while the results for GAC were less clear due to ambiguous results of a field and a parallel laboratory study. Both kinds of AC significantly reduced biota to soil accumulation factors (BSAFs) of PAHs in earthworms and plants. The GAC reduced the BSAFs of earthworms by an average of 47 ± 44% and the PAC amendment reduced them by 72 ± 19%. For the investigated plants the BSAFs were reduced by 46 ± 36% and 53 ± 22% by the GAC and PAC, respectively.

  18. DETAILED ANALYSIS OF THE MOST PROMISING ALTERNATIVES TO USING GRANULAR ACTIVATED CARBON TO TREAT 200-ZP-1 GROUNDWATER AND 200-PW-1 SOIL VAPOR

    SciTech Connect

    BYRNES ME, KALMAR JA

    2007-11-26

    This document presents a detailed evaluation of selected alternative treatment options to granular activated carbon (GAC) for removing carbon tetrachloride generated from the groundwater pump-and-treat system at the 200-ZP-I Operable Unit (OU) in the 200 West Area of the Hanford Site. This evaluation of alternative treatment options to GAC is also applicable to the vadose zone soil vapor extraction (SVE) system at the 200-PW-l OU, which is also located in the Hanford Site's 200 West Area.

  19. 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

  20. 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

  1. TREATMENT OF LANDFILL LEACHATE BY COUPLING COAGULATION-FLOCCULATION OR OZONATION TO GRANULAR ACTIVATED CARBON ADSORPTION.

    PubMed

    Oloibiri, Violet; Ufomba, Innocent; Chys, Michael; Audenaert, Wim; Demeestere, Kristof; Van Hulle, Stijn W H

    2015-01-01

    A major concern for landfilling facilities is the treatment of their leachate. To optimize organic matter removal from this leachate, the combination of two or more techniques is preferred in order to meet stringent effluent standards. In our study, coagulation-flocculation and ozonation are compared as pre- treatment steps for stabilized landfill leachate prior to granular activated carbon (GAC) adsorption. The efficiency of the pre treatment techniques is evaluated using COD and UVA254 measurements. For coagulation- flocculation, different chemicals are compared and optimal dosages are determined. After this, iron (III) chloride is selected for subsequent adsorption studies due to its high percentage of COD and UVA254 removal and good sludge settle-ability. Our finding show that ozonation as a single treatment is effective in reducing COD in landfill leachate by 66% compared to coagulation flocculation (33%). Meanwhile, coagulation performs better in UVA254 reduction than ozonation. Subsequent GAC adsorption of ozonated effluent, coagulated effluent and untreated leachate resulted in 77%, 53% and 8% total COD removal respectively (after 6 bed volumes). The effect of the pre-treatment techniques on GAC adsorption properties is evaluated experimentally and mathematically using Thomas and Yoon-Nelson models. Mathematical modelling of the experimental GAC adsorption data shows that ozonation increases the adsorption capacity and break through time with a factor of 2.5 compared to coagulation-flocculation. PMID:26630756

  2. Sorption of perfluorooctanoic acid, perfluorooctane sulfonate and perfluoroheptanoic acid on granular activated carbon.

    PubMed

    Zhang, Di; Luo, Qi; Gao, Bin; Chiang, Sheau-Yun Dora; Woodward, David; Huang, Qingguo

    2016-02-01

    The sorption of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoroheptanoic acid (PFHpA) on granular activated carbon (GAC) was characterized and compared to explore the underlying mechanisms. Sorption of the three perfluoroalkyl acids (PFAAs) on GAC appeared to be a rapid intra-particle diffusion process, which were well represented by the pseudo-second-order rate model with the sorption rate following the order PFOS > PFOA > PFHpA. Sorption isotherm data were well fitted by the Freundlich model with the sorption capacity (Kf) of PFOS, PFOA and PFHpA being 4.45, 2.42 and 1.66 respectively. This suggests that the hydrophilic head group on PFAAs, i.e. sulfonate vs carboxylic, has a strong influence on their sorption. Comparison between PFOA and PFHpA revealed that hydrophobicity could also play a role in the sorption of PFAAs on GAC when the fluorocarbon chain length is different. Analyses using Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy suggested possible formation of a negative charge-assisted H-bond between PFAAs and the functionalities on GAC surfaces, including non-aromatic ketones, sulfides, and halogenated hydrocarbons. PMID:26606188

  3. [Microwave thermal remediation of soil contaminated with crude oil enhanced by granular activated carbon].

    PubMed

    Li, Da-Wei; Zhang, Yao-Bin; Quan, Xie; Zhao, Ya-Zhi

    2009-02-15

    The advantage of rapid, selective and simultaneous heating of microwave heating technology was taken to remediate the crude oil-contaminated soil rapidly and to recover the oil contaminant efficiently. The contaminated soil was processed in the microwave field with addition of granular activated carbon (GAC), which was used as strong microwave absorber to enhance microwave heating of the soil mixture to remove the oil contaminant and recover it by a condensation system. The influences of some process parameters on the removal of the oil contaminant and the oil recovery in the remediation process were investigated. The results revealed that, under the condition of 10.0% GAC, 800 W microwave power, 0.08 MPa absolute pressure and 150 mL x min(-1) carrier gas (N2) flow-rate, more than 99% oil removal could be obtained within 15 min using this microwave thermal remediation enhanced by GAC; at the same time, about 91% of the oil contaminant could be recovered without significant changes in chemical composition. In addition, the experiment results showed that GAC can be reused in enhancing microwave heating of soil without changing its enhancement efficiency obviously.

  4. TREATMENT OF LANDFILL LEACHATE BY COUPLING COAGULATION-FLOCCULATION OR OZONATION TO GRANULAR ACTIVATED CARBON ADSORPTION.

    PubMed

    Oloibiri, Violet; Ufomba, Innocent; Chys, Michael; Audenaert, Wim; Demeestere, Kristof; Van Hulle, Stijn W H

    2015-01-01

    A major concern for landfilling facilities is the treatment of their leachate. To optimize organic matter removal from this leachate, the combination of two or more techniques is preferred in order to meet stringent effluent standards. In our study, coagulation-flocculation and ozonation are compared as pre- treatment steps for stabilized landfill leachate prior to granular activated carbon (GAC) adsorption. The efficiency of the pre treatment techniques is evaluated using COD and UVA254 measurements. For coagulation- flocculation, different chemicals are compared and optimal dosages are determined. After this, iron (III) chloride is selected for subsequent adsorption studies due to its high percentage of COD and UVA254 removal and good sludge settle-ability. Our finding show that ozonation as a single treatment is effective in reducing COD in landfill leachate by 66% compared to coagulation flocculation (33%). Meanwhile, coagulation performs better in UVA254 reduction than ozonation. Subsequent GAC adsorption of ozonated effluent, coagulated effluent and untreated leachate resulted in 77%, 53% and 8% total COD removal respectively (after 6 bed volumes). The effect of the pre-treatment techniques on GAC adsorption properties is evaluated experimentally and mathematically using Thomas and Yoon-Nelson models. Mathematical modelling of the experimental GAC adsorption data shows that ozonation increases the adsorption capacity and break through time with a factor of 2.5 compared to coagulation-flocculation.

  5. Evaluation of the treatment of reverse osmosis concentrates from municipal wastewater reclamation by coagulation and granular activated carbon adsorption.

    PubMed

    Sun, Ying-Xue; Yang, Zhe; Ye, Tao; Shi, Na; Tian, Yuan

    2016-07-01

    Reverse osmosis concentrate (ROC) from municipal wastewater reclamation reverse osmosis (mWRRO) contains elevated concentrations of contaminants which pose potential risks to aquatic environment. The treatment of ROC from an mWRRO using granular activated carbon (GAC) combined pretreatment of coagulation was optimized and evaluated. Among the three coagulants tested, ferric chloride (FeCl3) presented relatively higher DOC removal efficiency than polyaluminium chloride and lime at the same dosage and coagulation conditions. The removal efficiency of DOC, genotoxicity, and antiestrogenic activity concentration of the ROC could achieve 16.9, 18.9, and 39.7 %, respectively, by FeCl3 coagulation (with FeCl3 dosage of 180.22 mg/L), which can hardly reduce UV254 and genotoxicity normalized by DOC of the DOM with MW <5 kDa. However, the post-GAC adsorption column (with filtration velocity of 5.7 m/h, breakthrough point adsorption capacity of 0.22 mg DOC/g GAC) exhibited excellent removal efficiency on the dominant DOM fraction of MW <5 kDa in the ROC. The removal efficiency of DOC, UV254, and TDS in the ROC was up to 91.8, 96, and 76.5 %, respectively, by the FeCl3 coagulation and post-GAC adsorption. Also, the DOM with both genotoxicity and antiestrogenic activity were completely eliminated by the GAC adsorption. The results suggest that GAC adsorption combined pretreatment of FeCl3 coagulation as an efficient method to control organics, genotoxicity, and antiestrogenic activity in the ROC from mWRRO system. PMID:27032632

  6. Evaluation of the treatment of reverse osmosis concentrates from municipal wastewater reclamation by coagulation and granular activated carbon adsorption.

    PubMed

    Sun, Ying-Xue; Yang, Zhe; Ye, Tao; Shi, Na; Tian, Yuan

    2016-07-01

    Reverse osmosis concentrate (ROC) from municipal wastewater reclamation reverse osmosis (mWRRO) contains elevated concentrations of contaminants which pose potential risks to aquatic environment. The treatment of ROC from an mWRRO using granular activated carbon (GAC) combined pretreatment of coagulation was optimized and evaluated. Among the three coagulants tested, ferric chloride (FeCl3) presented relatively higher DOC removal efficiency than polyaluminium chloride and lime at the same dosage and coagulation conditions. The removal efficiency of DOC, genotoxicity, and antiestrogenic activity concentration of the ROC could achieve 16.9, 18.9, and 39.7 %, respectively, by FeCl3 coagulation (with FeCl3 dosage of 180.22 mg/L), which can hardly reduce UV254 and genotoxicity normalized by DOC of the DOM with MW <5 kDa. However, the post-GAC adsorption column (with filtration velocity of 5.7 m/h, breakthrough point adsorption capacity of 0.22 mg DOC/g GAC) exhibited excellent removal efficiency on the dominant DOM fraction of MW <5 kDa in the ROC. The removal efficiency of DOC, UV254, and TDS in the ROC was up to 91.8, 96, and 76.5 %, respectively, by the FeCl3 coagulation and post-GAC adsorption. Also, the DOM with both genotoxicity and antiestrogenic activity were completely eliminated by the GAC adsorption. The results suggest that GAC adsorption combined pretreatment of FeCl3 coagulation as an efficient method to control organics, genotoxicity, and antiestrogenic activity in the ROC from mWRRO system.

  7. 4-MCHM sorption to and desorption from granular activated carbon and raw coal.

    PubMed

    Jeter, T Scott; Sarver, Emily A; McNair, Harold M; Rezaee, Mohammad

    2016-08-01

    4-Methylcyclohexanemethanol (4-MCHM) is a saturated higher alicyclic primary alcohol that is used in the froth flotation process for cleaning coal. In early 2014, a large spill of crude chemical (containing primarily 4-MCHM) to the Elk River near Charleston, WV contaminated the local water supply. Carbon filters at the affected water treatment facility quickly became saturated, and the contaminated water was distributed to nearby homes and businesses. Sorption of 4-MCHM to granular activated carbon (GAC) was studied in the laboratory using head space (HS) analysis via gas chromatography with a flame ionization detector (GC-FID). Sorption to raw coal was also investigated, since this material may be of interest as a sorbent in the case of an on-site spill. As expected, sorption to both materials increased with decreased particle size and with increased exposure time; although exposure time proved to be much more important in the case of GAC than for coal. Under similar conditions, GAC sorbed more 4-MCHM than raw coal (e.g., 84.9 vs. 63.1 mg/g, respectively, for 20 × 30 mesh particles exposed to 860 mg/L 4-MCHM solution for 24 h). Desorption from both materials was additionally evaluated. Interestingly, desorption of 4-MCHM on a mass per mass basis was also higher for GAC than for raw coal. Overall, results indicated that GAC readily sorbs 4-MCHM but can also readily release a portion of the chemical, whereas coal sorbs somewhat less 4-MCHM but holds it tightly. PMID:27219291

  8. Comparing the removal of perchlorate when using single-walled carbon nanotubes (SWCNTs) or granular activated carbon: adsorption kinetics and thermodynamics.

    PubMed

    Lou, Jie C; Hsu, Yung S; Hsu, Kai L; Chou, Ming S; Han, Jia Y

    2014-01-01

    This study aims to remove perchlorate using single-walled carbon nanotubes (SWCNTs) or granular activated carbon (GAC). Dynamic and equilibrium adsorption experiments were performed to evaluate the thermodynamic behavior of perchlorate on SWCNTs and GAC. Key parameters affecting the adsorption, such as pH, ionic strength, and temperature were studied. The experimental results showed that the dynamic adsorption experiment achieved equilibrium in approximately eight hours. The adsorption capacity increased as the concentration of perchlorate increased or as the ionic strength decreased. The selected adsorption models were the modified Freundlich, the pseudo-1st-order, and the pseudo-2nd-order equations. The results showed that the modified Freundlich equation best described the kinetic adsorption processes. The maximal adsorption capacities of GAC and SWCNTs were 33.87-28.21 mg/g and 13.64 - 10.03 mg/g, respectively, at a constant temperature between 5°C and 45°C. The thermodynamic parameters, such as the equilibrium constant (K0 ), the standard free energy changes (ΔG°), the standard enthalpy change (ΔH°) and the standard entropy change (ΔS°), were obtained. The results of the isothermal equilibrium adsorption experiment showed that low pH levels, low ionic strength, and low-temperature conditions facilitated the perchlorate adsorption, indicating that GAC and SWCNTs are potential absorbents for water treatment. PMID:24410681

  9. Comparing the removal of perchlorate when using single-walled carbon nanotubes (SWCNTs) or granular activated carbon: adsorption kinetics and thermodynamics.

    PubMed

    Lou, Jie C; Hsu, Yung S; Hsu, Kai L; Chou, Ming S; Han, Jia Y

    2014-01-01

    This study aims to remove perchlorate using single-walled carbon nanotubes (SWCNTs) or granular activated carbon (GAC). Dynamic and equilibrium adsorption experiments were performed to evaluate the thermodynamic behavior of perchlorate on SWCNTs and GAC. Key parameters affecting the adsorption, such as pH, ionic strength, and temperature were studied. The experimental results showed that the dynamic adsorption experiment achieved equilibrium in approximately eight hours. The adsorption capacity increased as the concentration of perchlorate increased or as the ionic strength decreased. The selected adsorption models were the modified Freundlich, the pseudo-1st-order, and the pseudo-2nd-order equations. The results showed that the modified Freundlich equation best described the kinetic adsorption processes. The maximal adsorption capacities of GAC and SWCNTs were 33.87-28.21 mg/g and 13.64 - 10.03 mg/g, respectively, at a constant temperature between 5°C and 45°C. The thermodynamic parameters, such as the equilibrium constant (K0 ), the standard free energy changes (ΔG°), the standard enthalpy change (ΔH°) and the standard entropy change (ΔS°), were obtained. The results of the isothermal equilibrium adsorption experiment showed that low pH levels, low ionic strength, and low-temperature conditions facilitated the perchlorate adsorption, indicating that GAC and SWCNTs are potential absorbents for water treatment.

  10. Treatment of produced waters for removal of soluble organics and toxicity reduction using the GAC-FBR process

    SciTech Connect

    Sunday, A.; Cook, J.; Rajan, R.; Hickey, R.

    1995-12-31

    Pilot studies were conducted using 550 gallon per day biological Granular Activated Carbon-Fluidized Bed Reactor (GAC-FBR) systems to treat four different produced waters obtained from on-shore and off-shore production facilities. The organic and inorganic composition of these produced waters varied greatly from site to site. Total dissolved solids ranged from 0.8% to 18.5%; BTEX concentrations varied from 470 {mu}g/L to greater than 4500 {mu}g/L. Organic carbon concentrations of up to 440 mg/L were observed. Sulfide concentrations ranged from nil to greater than 800 mg/L as S. Organic loading rates up to 86.6 kgCOD/cu.m-day were applied to the GAC-FBR. Successful treatment was achieved at hydraulic retention times as low as 7 minutes. Essentially complete removal of BTEX and total volatile hydrocarbons was demonstrated for each of the produced water samples; significant removal of non-purgable dissolved organic carbon was also observed. Overall BTEX removals of >99.9% were consistently achieved. Results from several different toxicity assays indicated that the GAC-FBR was able to achieve complete reduction of toxicity with several of the produced waters tested.

  11. Disinfection by-products and microbial contamination in the treatment of pool water with granular activated carbon.

    PubMed

    Uhl, W; Hartmann, C

    2005-01-01

    For swimming pools, it is generally agreed that free chlorine levels have to be maintained to guarantee adequate disinfection. Recommended free chlorine levels can vary between 0.3 and 0.6 mg/L in Germany and up to 3 mg/L in other countries. Bathers introduce considerable amounts of organic matter, mainly in the form of such as urine and sweat, into the pool water. As a consequence, disinfection byproducts (DBPs) are formed. Regulations in Germany recommend levels of combined chlorine of less than 0.2 mg/L and levels of trihalomethanes (THMs) of less than 20 microg/L. Haloacetic acids (HAAs), haloacetonitriles (HANs), chloropicrin and chloral hydrate are also detected in considerable amounts. However, these compounds are not regulated yet. Swimming pool staff and swimmers, especially athletes, are primarily exposed to these byproducts by inhalation and/or dermal uptake. In Germany, new regulations for swimming pool water treatment generally require the use of activated carbon. In this project, three different types of granular activated carbon (GAC) (one standard GAC, two catalytic GACs) are compared for their long time behaviour in pool water treatment. In a pilot plant operated with real swimming pool water, production and removal of disinfection byproducts (THMs, HAAs, AOXs), of biodegradable substances (AOC), of bacteria (Pseudomonas aeruginosa, Legionella, coliforms, HPC) as well as the removal of chlorine and chloramines are monitored as function of GAC bed depth. Combined chlorine penetrates deeper in the filter bed than free chlorine does. However, both, free and combined chlorine removal efficiencies decrease over the time of filter operation. The decreases of removal efficiencies are also observed for parameters such as dissolved organic carbon, spectral absorption coefficient, adsorbable organic carbon and most of the disinfection byproducts. However, THMs, especially chloroform are produced in the filter bed. The GAC beds were contaminated microbially

  12. Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors.

    PubMed

    Choi, Young Chul; Li, Xu; Raskin, Lutgarde; Morgenroth, Eberhard

    2008-07-01

    Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions.

  13. The Fate and Transport of the SiO2 Nanoparticles in a Granular Activated Carbon Bed and Their Impact on the Removal of VOCs

    EPA Science Inventory

    Adsorption isotherm, adsorption kinetics and column breakthrough experiments evaluating trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) were conducted in the presence and absence of silica nanoparticles (SiO2 NPs). Zeta potential of the SiO

  14. 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...

  15. Technico-economic assessment of groundwater treatment by palladium-on-zeolite-catalyst in comparison to GAC fixed bed adsorbers.

    PubMed

    Bayer, P; Schüth, C

    2010-01-01

    A technico-economic comparison between palladium-on-zeolite (Pd/Y), and granular activated carbon (GAC) based methods of groundwater clean-up is presented. The treatment concepts are assessed by means of process-based cost functions that can be applied to a broad range of case-specific conditions. The analysis accounts for variability in cost and performance parameters and reduces the interplay of multiple factors to expressive indifference curves that can be used for identifying a favorable technology. The findings for the treatment of halogenated hydrocarbons reveal that the Pd/Y offers advantages compared to GAC use in case of high contaminant concentrations and for the treatment of lower halogenated compounds such as cis-Dichloroethene.

  16. Biological activated carbon as tertiary treatment for municipal-industrial wastewater

    SciTech Connect

    Smith, R.P.

    1986-01-01

    Granular Activated Carbon (GAC) as tertiary treatment to secondary biological effluent (trickling filters) was studied at Duck Creek Wastewater Treatment Plant, Garland, Texas. Two sets of pilot plants were operated for a period of eighteen months to determine optimum treatment conditions to obtain best effluent water quality. Performance of the pilot plants far exceeded expectations of pollutant removal capacity which could be achieved by adsorption alone. The sustained high level of treatment efficiency was attributed to biological activity within the GAC beds, generally referred to as Biological Activated Carbon. Increasing Empty Bed Contact Time (EBCT) improved performance, but pretreatments which increased dissolved oxygen concentration prior to GAC contact were more beneficial to effluent water quality than EBCT alone. No significant differences in water quality between pretreatment with oxygen or oxygen-ozone (10 mg/L applied ozone dose) were observed, demonstrating that the main benefit of oxygen-ozone was the oxygen component. Pretreatment with oxygen or oxygen-ozone resulted in nitrification, achieving 85% ammonia reduction, from 10 mg/L to 1 mg/L or less.

  17. Biological activated carbon fluidized-bed system to treat gasoline-contaminated groundwater

    SciTech Connect

    Voice, T.C.; Zhao, X.; Shi, J.; Hickey, R.F.

    1995-12-31

    An integrated biological granular activated carbon fluidized-bed reactor (GAC-FBR) and a biological fluidized-bed reactor (FBR) charged with nonactivated carbon were evaluated for treating groundwater contaminated with the gasoline constituents benzene, toluene, and xylenes (BTX). The systems were studied under several conditions including startup, steady-state, and step-load increase conditions. Development of bioactivity in the GAC-FBR was faster than in the FBR using a nonactivated carbon biomass carrier. Under two steady-state conditions, organic loading rates of 3 and 6 kg-chemical oxygen demand (COD)/m{sup 3}-day, BTX removal was similar in the two systems with more than 90% of applied BTX removed. The GAC-FBR produced superior effluent quality during step organic load rate (OLR) increases compared to the FBR. The results from an extremely high step OLR increase show the formation of partial oxidization products from the degradation of BTX. Significant adsorption capacity was still observed after the biofilm developed, although capacity gradually decreased over a 6-month period of operation to approximately 50% of its original value.

  18. Activated carbon from biomass

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

    2013-06-01

    Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

  19. Regulation of GacA in Pseudomonas chlororaphis Strains Shows a Niche Specificity

    PubMed Central

    Dubern, Jean-Frédéric; Li, Hui; Halliday, Nigel; Chernin, Leonid; Gao, Kexiang; Cámara, Miguel; Liu, Xiaoguang

    2015-01-01

    The GacS/GacA two-component system plays a central role in the regulation of a broad range of biological functions in many bacteria. In the biocontrol organism Pseudomonas chlororaphis, the Gac system has been shown to positively control quorum sensing, biofilm formation, and phenazine production, but has an overall negative impact on motility. These studies have been performed with strains originated from the rhizosphere predominantly. To investigate the level of conservation between the GacA regulation of biocontrol-related traits in P. chlororaphis isolates from different habitats, the studies presented here focused on the endophytic isolate G5 of P. chlororaphis subsp. aurantiaca. A gacA mutant deficient in the production of N-acylhomoserine lactones (AHLs) and phenazine was isolated through transposon mutagenesis. Further phenotypic characterization revealed that in strain G5, similar to other P. chlororaphis strains, a gacA mutation caused inability to produce biocontrol factors such as phenazine, HCN and proteases responsible for antifungal activity, but overproduced siderophores. LC-MS/MS analysis revealed that AHL production was also practically abolished in this mutant. However, the wild type exhibited an extremely diverse AHL pattern which has never been identified in P. chlororaphis. In contrast to other isolates of this organism, GacA in strain G5 was shown to negatively regulate biofilm formation and oxidative stress response whilst positively regulating cell motility and biosynthesis of indole-3-acetic acid (IAA). To gain a better understanding of the overall impact of GacA in G5, a comparative proteomic analysis was performed revealing that, in addition to some of the traits like phenazine mentioned above, GacA also negatively regulated lipopolysaccharide (LPS) and trehalose biosynthesis whilst having a positive impact on energy metabolism, an effect not previously described in P. chlororaphis. Consequently, GacA regulation shows a differential

  20. Comparison of nutshell granular activated carbons to commercial adsorbents for the purge-and-trap gas chromatographic analysis of volatile organic compounds.

    PubMed

    Wartelle, L H; Marshall, W E; Toles, C A; Johns, M M

    2000-05-26

    Granular activated carbons (GACs) made from agricultural by-products were investigated as adsorbents for short path thermal desorption gas chromatographic analysis of selected polar and nonpolar organic compounds. GACs made from macadamia nut, black walnut and hazelnut shells were compared to four commercially available adsorbents, namely, Tenax TA, Carboxen 569, Carbosieve SIII and coconut charcoal for their properties in purge-and-trap analysis. Adsorption values and breakthrough volumes were calculated for compounds from C3 and C6-C10. GACs derived from macadamia nut shells were found to adsorb and desorb between 80% (benzene) and 277% (ethylbenzene) more acetone (C3), benzene (C6), toluene (C7), ethyl- (C8), n-propyl- (C9), or sec.-butylbenzenes (C10) purged from water at the 100 ppb level than the commercial adsorbents tested. PMID:10893033

  1. Derivatives of Plant Phenolic Compound Affect the Type III Secretion System of Pseudomonas aeruginosa via a GacS-GacA Two-Component Signal Transduction System

    PubMed Central

    Yamazaki, Akihiro; Li, Jin; Zeng, Quan; Khokhani, Devanshi; Hutchins, William C.; Yost, Angela C.; Biddle, Eulandria; Toone, Eric J.

    2012-01-01

    Antibiotic therapy is the most commonly used strategy to control pathogenic infections; however, it has contributed to the generation of antibiotic-resistant bacteria. To circumvent this emerging problem, we are searching for compounds that target bacterial virulence factors rather than their viability. Pseudomonas aeruginosa, an opportunistic human pathogen, possesses a type III secretion system (T3SS) as one of the major virulence factors by which it secretes and translocates T3 effector proteins into human host cells. The fact that this human pathogen also is able to infect several plant species led us to screen a library of phenolic compounds involved in plant defense signaling and their derivatives for novel T3 inhibitors. Promoter activity screening of exoS, which encodes a T3-secreted toxin, identified two T3 inhibitors and two T3 inducers of P. aeruginosa PAO1. These compounds alter exoS transcription by affecting the expression levels of the regulatory small RNAs RsmY and RsmZ. These two small RNAs are known to control the activity of carbon storage regulator RsmA, which is responsible for the regulation of the key T3SS regulator ExsA. As RsmY and RsmZ are the only targets directly regulated by GacA, our results suggest that these phenolic compounds affect the expression of exoS through the GacSA-RsmYZ-RsmA-ExsA regulatory pathway. PMID:21968370

  2. Clinical evaluation of Gac extract (Momordica cochinchinensis) in an antiwrinkle cream formulation.

    PubMed

    Leevutinun, Pakapun; Krisadaphong, Panvipa; Petsom, Amorn

    2015-01-01

    The objective of this work was to evaluate the antioxidant and antityrosinase activities of Gac (Momordica cochinchinensis) extract and to clinically evaluate a Gac-containing antiwrinkle cream formulation. Gac extract exhibited higher antioxidant activity than vitamin C or E, as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH, 41.25 ± 0.34 mg TEAC/ml extract), 2, 2'-azinobis 3-ethylbenzothialine-6-sulfonic acid (ABTS, 47.70 ± 0.18 mg TEAC/ml extract), and ferric reducing antioxidant power (FRAP, 105.03 ± 2.326 mg TEAC/ml extract) scavenging. The antioxidant activity of Gac extract was 5.85- and 11.75-fold higher than that of vitamin E in the DPPH and ABTS assays, respectively. The FRAP assay indicated that the antioxidant activity of Gac extract was 2.91-fold higher than that of vitamin C. Gac extract also exhibited high tyrosinase inhibition (62.83% ± 1.99%). The tyrosinase inhibition activity of Gac extract was 1.51- and 2.06-fold greater than that of vitamins C and E, respectively. The safety and efficacy of the formulated Gac extract cream as an antiwrinkle agent and its promotion of skin moisturization and smoothness were investigated. Evaluation of acute skin tolerance indicated nonirritating properties. A clinical study revealed increases in cutaneous hydration. Average roughness was decreased, while smoothness was increased. Skin overlook analysis indicated skin roughness relief. These results indicate that the formulated Gac extract product is an effective antiwrinkle cream. PMID:26454905

  3. Clinical evaluation of Gac extract (Momordica cochinchinensis) in an antiwrinkle cream formulation.

    PubMed

    Leevutinun, Pakapun; Krisadaphong, Panvipa; Petsom, Amorn

    2015-01-01

    The objective of this work was to evaluate the antioxidant and antityrosinase activities of Gac (Momordica cochinchinensis) extract and to clinically evaluate a Gac-containing antiwrinkle cream formulation. Gac extract exhibited higher antioxidant activity than vitamin C or E, as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH, 41.25 ± 0.34 mg TEAC/ml extract), 2, 2'-azinobis 3-ethylbenzothialine-6-sulfonic acid (ABTS, 47.70 ± 0.18 mg TEAC/ml extract), and ferric reducing antioxidant power (FRAP, 105.03 ± 2.326 mg TEAC/ml extract) scavenging. The antioxidant activity of Gac extract was 5.85- and 11.75-fold higher than that of vitamin E in the DPPH and ABTS assays, respectively. The FRAP assay indicated that the antioxidant activity of Gac extract was 2.91-fold higher than that of vitamin C. Gac extract also exhibited high tyrosinase inhibition (62.83% ± 1.99%). The tyrosinase inhibition activity of Gac extract was 1.51- and 2.06-fold greater than that of vitamins C and E, respectively. The safety and efficacy of the formulated Gac extract cream as an antiwrinkle agent and its promotion of skin moisturization and smoothness were investigated. Evaluation of acute skin tolerance indicated nonirritating properties. A clinical study revealed increases in cutaneous hydration. Average roughness was decreased, while smoothness was increased. Skin overlook analysis indicated skin roughness relief. These results indicate that the formulated Gac extract product is an effective antiwrinkle cream.

  4. Evaluation of autotrophic growth of ammonia-oxidizers associated with granular activated carbon used for drinking water purification by DNA-stable isotope probing.

    PubMed

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki

    2013-12-01

    Nitrification is an important biological function of granular activated carbon (GAC) used in advanced drinking water purification processes. Newly discovered ammonia-oxidizing archaea (AOA) have challenged the traditional understanding of ammonia oxidation, which considered ammonia-oxidizing bacteria (AOB) as the sole ammonia-oxidizers. Previous studies demonstrated the predominance of AOA on GAC, but the contributions of AOA and AOB to ammonia oxidation remain unclear. In the present study, DNA-stable isotope probing (DNA-SIP) was used to investigate the autotrophic growth of AOA and AOB associated with GAC at two different ammonium concentrations (0.14 mg N/L and 1.4 mg N/L). GAC samples collected from three full-scale drinking water purification plants in Tokyo, Japan, had different abundance of AOA and AOB. These samples were fed continuously with ammonium and (13)C-bicarbonate for 14 days. The DNA-SIP analysis demonstrated that only AOA assimilated (13)C-bicarbonate at low ammonium concentration, whereas AOA and AOB exhibited autotrophic growth at high ammonium concentration. This indicates that a lower ammonium concentration is preferable for AOA growth. Since AOA could not grow without ammonium, their autotrophic growth was coupled with ammonia oxidation. Overall, our results point towards an important role of AOA in nitrification in GAC filters treating low concentration of ammonium.

  5. Three-component competitive adsorption model for fixed-bed and moving-bed granular activated carbon adsorbers. Part I. Model development.

    PubMed

    Schideman, Lance C; Mariñas, Benito J; Snoeyink, Vernon L; Campos, Carlos

    2006-11-01

    Heterogeneous natural organic matter (NOM) present in all natural waters impedes trace organic contaminant adsorption, and predictive modeling of granular activated carbon (GAC) adsorber performance is often compromised by inadequate accounting forthese competitive effects. Thus, a 3-component adsorption model, COMPSORB-GAC, is developed that separately tracks NOM adsorption and its competitive effects as a function of NOM surface loading. In this model, NOM is simplified into two fictive fractions with distinct competitive effects on trace compound adsorption: a smaller, strongly competing fraction that reduces equilibrium capacity and a larger pore-blocking fraction that reduces adsorption kinetics (both external film mass transfer and surface diffusion). COMPSORB-GAC tracks these two NOM fractions, along with the trace compound, and changes adsorption parameters according to the local surface loading of the two NOM fractions. Model parameters are allowed to vary both temporally and spatially to reflect differences in the NOM preloading conditions that occur in GAC columns. This dual-resistance model is based on homogeneous surface diffusion with external film mass-transfer limitations. The governing equations are expressed in a moving-grid finite-difference formulation to accommodate the modeling of spatially varying parameters and moving-bed reactors with counter-current adsorbent flow. A series of short-term adsorption tests with fresh and preloaded GAC is proposed to determine the necessary model input parameters. The accompanying manuscript demonstrates the parameterization procedure and verifies the model with experimental data. PMID:17144314

  6. Biofiltration of benzene contaminated air streams using compost-activated carbon filter media

    SciTech Connect

    Zhu, L.; Kocher, W.M.; Abumaizar, R.J.

    1998-12-31

    Three laboratory-scale biofilter columns were operated for 81 days to investigate the removal of benzene from a waste gas stream. The columns contain a mixture of yard waste and sludge compost as biomedia. Different amounts of granular activated carbon (GAC) are mixed with the compost in two of the three columns to evaluate the extent to which biofilter performance can be enhanced. The effects of different operating conditions on the performance of the removal of benzene from air were evaluated. More than 90% removal efficiency was observed for an influent benzene concentration of about 75 ppm and an air flow rate of 0.3 L/min. in all 3 columns under steady-state conditions. Under most cases of shock loading conditions, such as a sudden increase in the air flow rate, or the benzene concentration in the influent, the biofilters containing GAC provided higher removal efficiencies and more stable operation than the biofilter containing compost only.

  7. Controlling a toxic shock of pentachlorophenol (PCP) to anaerobic digestion using activated carbon addition.

    PubMed

    Xiao, Yeyuan; De Araujo, Cecilia; Sze, Chun Chau; Stuckey, David C

    2015-04-01

    Several powdered and granular activated carbons (PACs and GACs) were tested for adsorption of pentachlorophenol (PCP) in bench-scale anaerobic digestion reactors to control the toxicity of PCP to acetoclastic methanogenesis. Results showed that the adsorption capacities of PAC were reduced by 21-54%, depending on the PAC addition time, in the presence of the methanogenic sludge compared to the controls without sludge. As a preventive measure, PAC at a low dose of 20% (mass ratio to the VSS) added 24 h prior to, or simultaneously with, the addition of PCP could completely eliminate the toxic effects of PCP. At the same dose, PAC also enabled methanogenesis to recover immediately after the sludge had been exposed to PCP for 24h. GAC was not effective in enabling the recovery of methanogenesis due to its slow adsorption kinetics; however, at a dose of 80% it could partially ameliorate the toxic shock of PCP. PMID:25665874

  8. Development of an activated carbon-packed microbial bioelectrochemical system for azo dye degradation.

    PubMed

    Cardenas-Robles, Arely; Martinez, Eduardo; Rendon-Alcantar, Idelfonso; Frontana, Carlos; Gonzalez-Gutierrez, Linda

    2013-01-01

    A microbial bioelectrochemical reactor (BER) was employed for the degradation of azo dyes without the use of an external electron donor, using activated carbon (GAC) as a redox mediator. Contribution of pH values, open circuit potential (OCP), dye concentration and applied current were individually studied. A batch system and an upflow fixed bed bioreactor were built for analyzing the effect of the applied current on biodegradation of the azo dye Reactive Red 272. The presence of GAC (20% w/v) regulated both pH and OCP values in solution and led to a removal efficiency of 98%. Cyclic voltammetry results indicate a dependence of the electron transfer mechanism with the concentration of the azo compound. With these results, a continuous flow reactor operating with J=0.045 mA cm(-2), led to removal rates of 95% (± 3.5%) in a half-residence time of 1 hour. PMID:23128299

  9. Effect of DOM Size on Organic Micropollutant Adsorption by GAC.

    PubMed

    Kennedy, Anthony M; Summers, R Scott

    2015-06-01

    Granular activated carbon (GAC) adsorption of the micropollutants 2-methylisoborneol (MIB) and warfarin (WFN) at ng/L levels was investigated in five waters with isolated natural dissolved organic matter (DOM) held at a constant dissolved organic carbon concentration. Each water was evaluated for competitive adsorption effects based on the pretreatment of ultrafiltration, coagulation, and additional background micropollutants. Using the breakthrough with unfractionated DOM as a baseline, on average, the water with lower molecular weight (MW) DOM decreased MIB and WFN adsorption capacity by 59%, whereas the water with higher MW DOM increased MIB and WFN adsorption capacity by 64%. All waters showed similar decreasing MIB and WFN adsorption capacity with increasing empty bed contact time (EBCT), with more dramatic effects seen for the more strongly adsorbing WFN. On average, MIB and WFN adsorption kinetics were two times slower in the water with higher MW DOM compared to the water with lower MW DOM, as described by the intraparticle pore diffusion tortuosity. Increased adsorption competition from 27 micropollutants other than MIB and WFN at environmentally relevant concentrations had little to no effect on MIB and WFN breakthrough behavior. Any competitive effect from background micropollutants became indiscernible at longer EBCTs. PMID:25955134

  10. TREATMENT OF CERCLA (COMPREHENSIVE ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY ACT) LEACHATES BY CARBON-ASSISTED ANAEROBIC FLUIDIZED BEDS (Journal)

    EPA Science Inventory

    Two anaerobic granular activated carbon (GAC) expanded-bed bioreactors were tested as pretreatment units for the decontamination of hazardous leachates containing volatile and semivolatile synthetic organic chemicals (SOCs). The different characteristics of the two leachate feed...

  11. Impact of UV-H2O2 Advanced Oxidation and Aging Processes on GAC Capacity for the Removal of Cyanobacterial Taste and Odor Compounds.

    PubMed

    Zamyadi, Arash; Sawade, Emma; Ho, Lionel; Newcombe, Gayle; Hofmann, Ron

    2015-01-01

    Cyanobacteria and their taste and odor (T&O) compounds are a growing concern in water sources globally. Geosmin and 2-methylisoborneol (MIB) are the most commonly detected T&O compounds associated with cyanobacterial presence in drinking water sources. The use of ultraviolet and hydrogen peroxide (H2O2) as an advanced oxidation treatment for T&O control is an emerging technology. However, residual H2O2 (>80% of the initial dose) has to be removed from water prior final disinfection. Recently, granular activated carbon (GAC) is used to remove H2O2 residual. The objective of this study is to assess the impact of H2O2 quenching and aging processes on GAC capacity for the removal of geosmin and MIB. Pilot columns with different types of GAC and presence/absence of H2O2 have been used for this study. H2O2 removal for the operational period of 6 months has no significant impact on GAC capacity to remove the geosmin and MIB from water.

  12. Impact of UV–H2O2 Advanced Oxidation and Aging Processes on GAC Capacity for the Removal of Cyanobacterial Taste and Odor Compounds

    PubMed Central

    Zamyadi, Arash; Sawade, Emma; Ho, Lionel; Newcombe, Gayle; Hofmann, Ron

    2015-01-01

    Cyanobacteria and their taste and odor (T&O) compounds are a growing concern in water sources globally. Geosmin and 2-methylisoborneol (MIB) are the most commonly detected T&O compounds associated with cyanobacterial presence in drinking water sources. The use of ultraviolet and hydrogen peroxide (H2O2) as an advanced oxidation treatment for T&O control is an emerging technology. However, residual H2O2 (>80% of the initial dose) has to be removed from water prior final disinfection. Recently, granular activated carbon (GAC) is used to remove H2O2 residual. The objective of this study is to assess the impact of H2O2 quenching and aging processes on GAC capacity for the removal of geosmin and MIB. Pilot columns with different types of GAC and presence/absence of H2O2 have been used for this study. H2O2 removal for the operational period of 6 months has no significant impact on GAC capacity to remove the geosmin and MIB from water. PMID:26462247

  13. Granular Activated Carbon Treatment May Result in Higher Predicted Genotoxicity in the Presence of Bromide.

    PubMed

    Krasner, Stuart W; Lee, Tiffany Chih Fen; Westerhoff, Paul; Fischer, Natalia; Hanigan, David; Karanfil, Tanju; Beita-Sandí, Wilson; Taylor-Edmonds, Liz; Andrews, Robert C

    2016-09-01

    Certain unregulated disinfection byproducts (DBPs) are more of a health concern than regulated DBPs. Brominated species are typically more cytotoxic and genotoxic than their chlorinated analogs. The impact of granular activated carbon (GAC) on controlling the formation of regulated and selected unregulated DBPs following chlorine disinfection was evaluated. The predicted cyto- and genotoxicity of DBPs was calculated using published potencies based on the comet assay for Chinese hamster ovary cells (assesses the level of DNA strand breaks). Additionally, genotoxicity was measured using the SOS-Chromotest (detects DNA-damaging agents). The class sum concentrations of trihalomethanes, haloacetic acids, and unregulated DBPs, and the SOS genotoxicity followed the breakthrough of dissolved organic carbon (DOC), however the formation of brominated species did not. The bromide/DOC ratio was higher than the influent through much of the breakthrough curve (GAC does not remove bromide), which resulted in elevated brominated DBP concentrations in the effluent. Based on the potency of the haloacetonitriles and halonitromethanes, these nitrogen-containing DBPs were the driving agents of the predicted genotoxicity. GAC treatment of drinking or reclaimed waters with appreciable levels of bromide and dissolved organic nitrogen may not control the formation of unregulated DBPs with higher genotoxicity potencies. PMID:27467860

  14. Roles of the Gac-Rsm pathway in the regulation of phenazine biosynthesis in Pseudomonas chlororaphis 30-84

    PubMed Central

    Wang, Dongping; Lee, Sung-Hee; Seeve, Candace; Yu, Jun Myoung; Pierson, Leland S; Pierson, Elizabeth A

    2013-01-01

    The GacS/GacA two-component regulatory system activates the production of secondary metabolites including phenazines crucial for biological control activity in Pseudomonas chlororaphis 30-84. To better understand the role of the Gac system on phenazine regulation, transcriptomic analyses were conducted by comparing the wild-type strain to a gacA mutant. RNA-seq analysis identified 771 genes under GacA control, including many novel genes. Consistent with previous findings, phenazine biosynthetic genes were significantly downregulated in a gacA mutant. The transcript abundances of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS, and pip also were reduced. Moreover, the transcript abundance of three noncoding RNAs (ncRNAs) including rsmX, rsmY, and rsmZ was significantly decreased by gacA mutation consistent with the presence of consensus GacA-binding sites associated with their promoters. Our results also demonstrated that constitutive expression of rsmZ from a non-gac regulated promoter resulted in complete restoration of N-acyl-homoserine lactone (AHL) and phenazine production as well as the expression of other gac-dependent secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production also was investigated. Overexpression of rsmE, but not rsmA, resulted in decreased AHL and phenazine production in P. chlororaphis, and only a mutation in rsmE bypassed the requirement for GacA in phenazine gene expression. In contrast, constitutive expression of the phzI/phzR quorum sensing system did not rescue phenazine production in the gacA mutant, indicating the direct posttranscriptional control by Gac on the phenazine biosynthetic genes. On the basis of these results, we propose a model to illustrate the hierarchic role of phenazine regulators modulated by Gac in the control of phenazine production. The transcriptomic analysis also was used to identify additional genes regulated by GacA that may contribute to the biological control

  15. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  16. Application of integrated ozone and granular activated carbon for decolorization and chemical oxygen demand reduction of vinasse from alcohol distilleries.

    PubMed

    Hadavifar, Mojtaba; Younesi, Habibollah; Zinatizadeh, Ali Akbar; Mahdad, Faezeh; Li, Qin; Ghasemi, Zahra

    2016-04-01

    This study investigates the treatment of the distilleries vinasse using a hybrid process integrating ozone oxidation and granular activated carbons (GAC) in both batch and continuous operation mode. The batch-process studies have been carried out to optimize initial influent pH, GAC doses, the effect of the ozone (O3) and hydrogen peroxide (H2O2) concentrations on chemical oxygen demand (COD) and color removal of the distilleries vinasse. The continuous process was carried out on GAC and ozone treatment alone as well as the hybrid process comb both methods to investigate the synergism effectiveness of the two methods for distilleries vinasse COD reduction and color removal. In a continuous process, the Yan model described the experimental data better than the Thomas model. The efficiency of ozonation of the distilleries vinasse was more effective for color removal (74.4%) than COD removal (25%). O3/H2O2 process was not considerably more effective on COD and color removal. Moreover, O3/GAC process affected negatively on the removal efficiency by reducing COD and color from distilleries vinasse. The negative effect decreased by increasing pH value of the influent. PMID:26789200

  17. Developing Polycation-Clay Sorbents for Efficient Filtration of Diclofenac: Effect of Dissolved Organic Matter and Comparison to Activated Carbon.

    PubMed

    Kohay, Hagay; Izbitski, Avital; Mishael, Yael G

    2015-08-01

    The presence of nanoconcentrations of persistent pharmaceuticals in treated wastewater effluent and in surface water has been frequently reported. A novel organic-inorganic hybrid sorbent based on adsorbing quarternized poly vinylpyridinium-co-styrene (QPVPcS) to montmorillonite (MMT) was designed for the removal of the anionic micropollutants. QPVPcS-clay composites were characterized by X-ray diffraction, FTIR, thermal gravimetric analysis, Zeta potential and element analysis. Based on these measurements polymer-clay micro- and nanostructures, as a function of polymer loading, were suggested. The affinity of the anionic pharmaceutical, diclofenac (DCF), to the composite was high and did not decrease dramatically with an increase of ionic strength, indicating that the interactions are not only electrostatic. The presence of humic acid (HA) did not hinder DCF removal by the composite; whereas, its filtration by granulated activated carbon (GAC) was compromised in the presence of HA. The kinetics and adsorption at equilibrium of DCF to the composite and to GAC were measured and modeled by the time dependent Langmuir equation. The adsorption of DCF to the composite was significantly faster than to GAC. Accordingly, the filtration of micro- and nanoconcentrations of DCF by composite columns, in the presence of HA, was more efficient than by GAC columns. PMID:26126078

  18. Application of integrated ozone and granular activated carbon for decolorization and chemical oxygen demand reduction of vinasse from alcohol distilleries.

    PubMed

    Hadavifar, Mojtaba; Younesi, Habibollah; Zinatizadeh, Ali Akbar; Mahdad, Faezeh; Li, Qin; Ghasemi, Zahra

    2016-04-01

    This study investigates the treatment of the distilleries vinasse using a hybrid process integrating ozone oxidation and granular activated carbons (GAC) in both batch and continuous operation mode. The batch-process studies have been carried out to optimize initial influent pH, GAC doses, the effect of the ozone (O3) and hydrogen peroxide (H2O2) concentrations on chemical oxygen demand (COD) and color removal of the distilleries vinasse. The continuous process was carried out on GAC and ozone treatment alone as well as the hybrid process comb both methods to investigate the synergism effectiveness of the two methods for distilleries vinasse COD reduction and color removal. In a continuous process, the Yan model described the experimental data better than the Thomas model. The efficiency of ozonation of the distilleries vinasse was more effective for color removal (74.4%) than COD removal (25%). O3/H2O2 process was not considerably more effective on COD and color removal. Moreover, O3/GAC process affected negatively on the removal efficiency by reducing COD and color from distilleries vinasse. The negative effect decreased by increasing pH value of the influent.

  19. Granulated activated carbon modified with hydrophobic silica aerogel-potential composite materials for the removal of uranium from aqueous solutions.

    PubMed

    Coleman, Sabre J; Coronado, Paul R; Maxwell, Robert S; Reynolds, John G

    2003-05-15

    Aqueous solutions of 100 parts per billion (ppb) uranium at pH 7 were treated with granulated activated carbon (GAC) that had been modified with various formulations of hydrophobic aerogels. The composite materials were found to be superior in removing uranium from a stock solution compared to GAC alone evaluated by a modified ASTM D 3860-98 method for batch testing. The testing results were evaluated using a Freundlich adsorption model. The best performing material has parameters of n = 287 and Kf = 1169 compared to n = 1.00, and Kf = 20 for GAC alone. The composite materials were formed by mixing (CH3O)4Si with the hydrophobic sol-gel precursor, (CH3O)3SiCH2CH2CF3 and with specified modifiers, such as H3PO4, Ca(NO3)2, and (C2H5O)3SiCH2CH2P(O)(OC2H5)2, elation catalysts, and GAC in a supercritical reactor system. After gelation, supercritical extraction, and sieving, the composites were tested. Characterization by FTIR and 31P NMR indicate the formation of phosphate in the case of the H3PO4 and Ca(NO3)2 composites and phosphonic acid related compounds in the phosphonate composite. These composite materials have potential application in the clean up of groundwater at DOE and other facilities.

  20. 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.

  1. Activated carbon material

    DOEpatents

    Evans, A. Gary

    1978-01-01

    Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

  2. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    PubMed

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement.

  3. [Study on the start-up of anaerobic ammonium oxidation process in biological activated carbon reactor].

    PubMed

    Lai, Wei-Yi; Zhou, Wei-Li; He, Sheng-Bing

    2013-08-01

    In order to shorten the start-up time of anaerobic ammonium oxidation (ANAMMOX) reactor, biological activated cabon reactor was applied. Three lab scale UASB reactors were seeded with anaerobic sludge, fed with synthetic wastewater containing ammonia and nitrite, and supplemented with granular activated carbon on day 0, 33 and 56, respectively. The nitrogen removal performance of the first reactor, into which GAC was added on day 0, showed no significant improvement in 90 days. After being suspended for about one month, the secondary start-up of this reactor succeeded in another 33 days (totally 123 days). 49 d and 85 d were taken for the other two reactors started up by the addition of GAC on day 33 and 56, respectively. After the reactors were started up, the average removal rates of total nitrogen were 89.8%, 86.7% and 86.7%, respectively. The start-up process could be divided into four stages, namely, the bacterial autolysis phase, the lag phase, the improve phase and the stationary phase, and the best time for adding GAC carrier was right after the start of the lag phase.

  4. Fabrication of granular activated carbons derived from spent coffee grounds by entrapment in calcium alginate beads for adsorption of acid orange 7 and methylene blue.

    PubMed

    Jung, Kyung-Won; Choi, Brian Hyun; Hwang, Min-Jin; Jeong, Tae-Un; Ahn, Kyu-Hong

    2016-11-01

    Biomass-based granular activated carbon was successfully prepared by entrapping activated carbon powder derived from spent coffee grounds into calcium-alginate beads (SCG-GAC) for the removal of acid orange 7 (AO7) and methylene blue (MB) from aqueous media. The dye adsorption process is highly pH-dependent and essentially independent of ionic effects. The adsorption kinetics was satisfactorily described by the pore diffusion model, which revealed that pore diffusion was the rate-limiting step during the adsorption process. The equilibrium isotherm and isosteric heat of adsorption indicate that SCG-GAC possesses an energetically heterogeneous surface and operates via endothermic process in nature. The maximum adsorption capacities of SCG-GAC for AO7 (pH 3.0) and MB (pH 11.0) adsorption were found to be 665.9 and 986.8mg/g at 30°C, respectively. Lastly, regeneration tests further confirmed that SCG-GAC has promising potential in its reusability, showing removal efficiency of more than 80% even after seven consecutive cycles.

  5. Fabrication of granular activated carbons derived from spent coffee grounds by entrapment in calcium alginate beads for adsorption of acid orange 7 and methylene blue.

    PubMed

    Jung, Kyung-Won; Choi, Brian Hyun; Hwang, Min-Jin; Jeong, Tae-Un; Ahn, Kyu-Hong

    2016-11-01

    Biomass-based granular activated carbon was successfully prepared by entrapping activated carbon powder derived from spent coffee grounds into calcium-alginate beads (SCG-GAC) for the removal of acid orange 7 (AO7) and methylene blue (MB) from aqueous media. The dye adsorption process is highly pH-dependent and essentially independent of ionic effects. The adsorption kinetics was satisfactorily described by the pore diffusion model, which revealed that pore diffusion was the rate-limiting step during the adsorption process. The equilibrium isotherm and isosteric heat of adsorption indicate that SCG-GAC possesses an energetically heterogeneous surface and operates via endothermic process in nature. The maximum adsorption capacities of SCG-GAC for AO7 (pH 3.0) and MB (pH 11.0) adsorption were found to be 665.9 and 986.8mg/g at 30°C, respectively. Lastly, regeneration tests further confirmed that SCG-GAC has promising potential in its reusability, showing removal efficiency of more than 80% even after seven consecutive cycles. PMID:27494099

  6. 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

  7. Removal of bromide and bromate from drinking water using granular activated carbon.

    PubMed

    Zhang, Yong-Qing; Wu, Qing-Ping; Zhang, Ju-Mei; Yang, Xiu-Hua

    2015-03-01

    Granular activated carbon (GAC) was used to remove bromide (Br⁻) and bromate (BrO(3)(-)) from drinking water in both bench- and pilot-scale experiments. The present study aims to minimize BrO(3)(-) formation and eliminate BrO(3)(-) generated during the ozonation of drinking water, particularly in packaged drinking water. Results show that the Br⁻ and BrO(3)(-) levels in GAC-treated water decreased in both bench- and pilot-scale experiments. In the bench-scale experiments, when the empty bed contact time (EBCT) was 5 min, the highest reduction rates of Br(-) in the mineral and ultrapure water were found to be 74.9% and 91.2%, respectively, and those of BrO(3)(-) were 94.4% and 98.8%, respectively. The GAC capacity for Br⁻ and BrO(3)(-) removal increased with the increase in EBCT. Reduction efficiency was better in ultrapure water than in mineral water. In the pilot-scale experiments, the minimum reduction rates of Br⁻ and BrO(3)(-) were 38.5% and 73.2%, respectively. PMID:25719467

  8. Removal of bromide and bromate from drinking water using granular activated carbon.

    PubMed

    Zhang, Yong-Qing; Wu, Qing-Ping; Zhang, Ju-Mei; Yang, Xiu-Hua

    2015-03-01

    Granular activated carbon (GAC) was used to remove bromide (Br⁻) and bromate (BrO(3)(-)) from drinking water in both bench- and pilot-scale experiments. The present study aims to minimize BrO(3)(-) formation and eliminate BrO(3)(-) generated during the ozonation of drinking water, particularly in packaged drinking water. Results show that the Br⁻ and BrO(3)(-) levels in GAC-treated water decreased in both bench- and pilot-scale experiments. In the bench-scale experiments, when the empty bed contact time (EBCT) was 5 min, the highest reduction rates of Br(-) in the mineral and ultrapure water were found to be 74.9% and 91.2%, respectively, and those of BrO(3)(-) were 94.4% and 98.8%, respectively. The GAC capacity for Br⁻ and BrO(3)(-) removal increased with the increase in EBCT. Reduction efficiency was better in ultrapure water than in mineral water. In the pilot-scale experiments, the minimum reduction rates of Br⁻ and BrO(3)(-) were 38.5% and 73.2%, respectively.

  9. In situ treatment with activated carbon reduces bioaccumulation in aquatic food chains.

    PubMed

    Kupryianchyk, D; Rakowska, M I; Roessink, I; Reichman, E P; Grotenhuis, J T C; Koelmans, A A

    2013-05-01

    In situ activated carbon (AC) amendment is a new direction in contaminated sediment management, yet its effectiveness and safety have never been tested on the level of entire food chains including fish. Here we tested the effects of three different AC treatments on hydrophobic organic chemical (HOC) concentrations in pore water, benthic invertebrates, zooplankton, and fish (Leuciscus idus melanotus). AC treatments were mixing with powdered AC (PAC), mixing with granular AC (GAC), and addition-removal of GAC (sediment stripping). The AC treatments resulted in a significant decrease in HOC concentrations in pore water, benthic invertebrates, zooplankton, macrophytes, and fish. In 6 months, PAC treatment caused a reduction of accumulation of polychlorobiphenyls (PCB) in fish by a factor of 20, bringing pollutant levels below toxic thresholds. All AC treatments supported growth of fish, but growth was inhibited in the PAC treatment, which was likely explained by reduced nutrient concentrations, resulting in lower zooplankton (i.e., food) densities for the fish. PAC treatment may be advised for sites where immediate ecosystem protection is required. GAC treatment may be equally effective in the longer term and may be adequate for vulnerable ecosystems where longer-term protection suffices. PMID:23544454

  10. In situ treatment with activated carbon reduces bioaccumulation in aquatic food chains.

    PubMed

    Kupryianchyk, D; Rakowska, M I; Roessink, I; Reichman, E P; Grotenhuis, J T C; Koelmans, A A

    2013-05-01

    In situ activated carbon (AC) amendment is a new direction in contaminated sediment management, yet its effectiveness and safety have never been tested on the level of entire food chains including fish. Here we tested the effects of three different AC treatments on hydrophobic organic chemical (HOC) concentrations in pore water, benthic invertebrates, zooplankton, and fish (Leuciscus idus melanotus). AC treatments were mixing with powdered AC (PAC), mixing with granular AC (GAC), and addition-removal of GAC (sediment stripping). The AC treatments resulted in a significant decrease in HOC concentrations in pore water, benthic invertebrates, zooplankton, macrophytes, and fish. In 6 months, PAC treatment caused a reduction of accumulation of polychlorobiphenyls (PCB) in fish by a factor of 20, bringing pollutant levels below toxic thresholds. All AC treatments supported growth of fish, but growth was inhibited in the PAC treatment, which was likely explained by reduced nutrient concentrations, resulting in lower zooplankton (i.e., food) densities for the fish. PAC treatment may be advised for sites where immediate ecosystem protection is required. GAC treatment may be equally effective in the longer term and may be adequate for vulnerable ecosystems where longer-term protection suffices.

  11. Arsenate sorption by hydrous ferric oxide incorporated onto granular activated carbon with phenol formaldehyde resins coating.

    PubMed

    Zhuang, J M; Hobenshield, E; Walsh, T

    2008-04-01

    A simple and effective method was developed using phenol formaldehyde (PF) resins to immobilize hydrous ferric oxide (HFO) onto granular activated carbon (GAC). The resulting sorbent possesses advantages for both the ferric oxide and the GAC, such as a great As-affinity of ferric oxide, large surface area of GAC, and enhanced physical strength. The studies showed that within one hour this sorbent was able to remove 85% of As(V) from water containing an initial As(V) concentration of 1.74 mg l(-1). The As(V) adsorption onto the sorbent was found to follow a pseudo-second order kinetics model. The adsorption isotherms were interpreted in terms of the Langmuir and Freundlich models. The equilibrium data fitted very well to both models. Column tests showed that this sorbent was able to achieve residual concentrations of As(V) in a range of 0.1-2.0 microg l(-1) while continuously treating about 180 bed volume (BV, 130 ml-BV) of arsenate water with an initial As(V) concentration of 1886 microg l(-1) at a filtration rate of 13.5 ml min(-1), i.e., an empty bed contact time (EBCT) of 9.6 min and a gram sorbent contact time (GSCT) of 0.15 min. After passing 635 BV of arsenate water, the exhausted sorbent was then tested by the Toxicity Characteristic Leaching Procedure (TCLP, US EPA Method 1311) test, and classified as non-hazardous for disposal. Hence, this HFO-PF-coated GAC has the capability to remove As(V) from industrial wastewater containing As(V) levels of about 2 mg l(-1). PMID:18619145

  12. Adsorption of organic contaminants by graphene nanosheets, carbon nanotubes and granular activated carbons under natural organic matter preloading conditions.

    PubMed

    Ersan, Gamze; Kaya, Yasemin; Apul, Onur G; Karanfil, Tanju

    2016-09-15

    The effect of NOM preloading on the adsorption of phenanthrene (PNT) and trichloroethylene (TCE) by pristine graphene nanosheets (GNS) and graphene oxide nanosheet (GO) was investigated and compared with those of a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based granular activated carbons (GACs). PNT uptake was higher than TCE by all adsorbents on both mass and surface area bases. This was attributed to the hydrophobicity of PNT. The adsorption capacities of PNT and TCE depend on the accessibility of the organic molecules to the inner regions of the adsorbent which was influenced from the molecular size of OCs. The adsorption capacities of all adsorbents decreased as a result of NOM preloading due to site competition and/or pore/interstice blockage. However, among all adsorbents, GO was generally effected least from the NOM preloading for PNT, whereas there was not observed any trend of NOM competition with a specific adsorbent for TCE. In addition, SWCNT was generally affected most from the NOM preloading for TCE and there was not any trend for PNT. The overall results indicated that the fate and transport of organic contaminants by GNSs and CNTs type of nanoadsorbents and GACs in different natural systems will be affected by water quality parameters, characteristics of adsorbent, and properties of adsorbate.

  13. Adsorption of organic contaminants by graphene nanosheets, carbon nanotubes and granular activated carbons under natural organic matter preloading conditions.

    PubMed

    Ersan, Gamze; Kaya, Yasemin; Apul, Onur G; Karanfil, Tanju

    2016-09-15

    The effect of NOM preloading on the adsorption of phenanthrene (PNT) and trichloroethylene (TCE) by pristine graphene nanosheets (GNS) and graphene oxide nanosheet (GO) was investigated and compared with those of a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based granular activated carbons (GACs). PNT uptake was higher than TCE by all adsorbents on both mass and surface area bases. This was attributed to the hydrophobicity of PNT. The adsorption capacities of PNT and TCE depend on the accessibility of the organic molecules to the inner regions of the adsorbent which was influenced from the molecular size of OCs. The adsorption capacities of all adsorbents decreased as a result of NOM preloading due to site competition and/or pore/interstice blockage. However, among all adsorbents, GO was generally effected least from the NOM preloading for PNT, whereas there was not observed any trend of NOM competition with a specific adsorbent for TCE. In addition, SWCNT was generally affected most from the NOM preloading for TCE and there was not any trend for PNT. The overall results indicated that the fate and transport of organic contaminants by GNSs and CNTs type of nanoadsorbents and GACs in different natural systems will be affected by water quality parameters, characteristics of adsorbent, and properties of adsorbate. PMID:27107611

  14. Inhibition of tumor growth and angiogenesis by water extract of Gac fruit (Momordica cochinchinensis Spreng).

    PubMed

    Tien, Pham Gia; Kayama, Fujio; Konishi, Fumio; Tamemoto, Hiroyuki; Kasono, Keizo; Hung, Nguyen Thi Kim; Kuroki, Masatoshi; Ishikawa, San-E; Van, Chuyen Nguyen; Kawakami, Masanobu

    2005-04-01

    The antitumor activity of the crude water extract from Gac fruit (Momordica cochinchinensis) was investigated in vivo and in vitro. A water extract prepared from 0.75 and 0.25 mg dry weight of Gac fruit per gram body weight was given daily to Balb/c mice (n=15/group). The water extract inhibited the growth of the colon 26-20 adenocarcinoma cell line, transplanted in Balb/c mice, reducing wet tumor weight by 23.6%. Histological and immunohistochemical results indicated that Gac water extract reduced the density of blood vessels around the carcinoma. The water extract also produced a marked suppression of cell proliferation in colon 26-20 and HepG2 cells. Cell cycle analysis demonstrated a significant accumulation of cells in the S phase by water extract. Immunoblotting showed that cyclin A, Cdk2, p27waf1/Kip1 were down-regulated, whereas the protein level of p21waf1/Cip1 was not decreased. Treatment of colon 26-20 cells with Gac extract induced necrosis rather than apoptosis. The antitumor component was confirmed as a protein with molecular weight of 35 kDa, retained in the water-soluble high molecular weight fraction. Thus, the bioactive antitumor compound in Gac extract is a protein, which is distinct from lycopene, another compound in Gac fruit with potential antitumor activity. PMID:15753981

  15. Inhibition of tumor growth and angiogenesis by water extract of Gac fruit (Momordica cochinchinensis Spreng).

    PubMed

    Tien, Pham Gia; Kayama, Fujio; Konishi, Fumio; Tamemoto, Hiroyuki; Kasono, Keizo; Hung, Nguyen Thi Kim; Kuroki, Masatoshi; Ishikawa, San-E; Van, Chuyen Nguyen; Kawakami, Masanobu

    2005-04-01

    The antitumor activity of the crude water extract from Gac fruit (Momordica cochinchinensis) was investigated in vivo and in vitro. A water extract prepared from 0.75 and 0.25 mg dry weight of Gac fruit per gram body weight was given daily to Balb/c mice (n=15/group). The water extract inhibited the growth of the colon 26-20 adenocarcinoma cell line, transplanted in Balb/c mice, reducing wet tumor weight by 23.6%. Histological and immunohistochemical results indicated that Gac water extract reduced the density of blood vessels around the carcinoma. The water extract also produced a marked suppression of cell proliferation in colon 26-20 and HepG2 cells. Cell cycle analysis demonstrated a significant accumulation of cells in the S phase by water extract. Immunoblotting showed that cyclin A, Cdk2, p27waf1/Kip1 were down-regulated, whereas the protein level of p21waf1/Cip1 was not decreased. Treatment of colon 26-20 cells with Gac extract induced necrosis rather than apoptosis. The antitumor component was confirmed as a protein with molecular weight of 35 kDa, retained in the water-soluble high molecular weight fraction. Thus, the bioactive antitumor compound in Gac extract is a protein, which is distinct from lycopene, another compound in Gac fruit with potential antitumor activity.

  16. Genetic evidence that the gacA gene encodes the cognate response regulator for the lemA sensor in Pseudomonas syringae.

    PubMed Central

    Rich, J J; Kinscherf, T G; Kitten, T; Willis, D K

    1994-01-01

    Mutational analysis of the bean-pathogenic Pseudomonas syringae pv. syringae strain B728a has led to the genetic identification of the gacA gene as encoding the response regulator for the unlinked lemA sensor kinase. The analysis of a collection of spontaneous mutants of P. syringae pv. syringae suggested that the gacA gene was involved in lesion formation and the production of protease and syringomycin. The gacA gene originally was identified as a regulator of extracellular antibiotic production by Pseudomonas fluorescens, and the predicted GacA protein is a member of the FixJ family of bacterial response regulators. The sequence of the putative B728a GacA protein revealed 92% identity with the P. fluorescens GacA protein. An insertional mutation within the P. syringae pv. syringae gacA gene abrogated lesion formation on beans, production of extracellular protease, and production of the toxin syringomycin, the same phenotypes affected by a lemA mutation. DNA sequence analysis identified the P. syringae pv. syringae uvrC gene immediately downstream of the gacA gene, an arrangement conserved in P. fluorescens and Escherichia coli. The gacA insertional mutant was sensitive to UV, presumably because of polarity on transcription of the downstream uvrC gene. Southwestern (DNA-protein) analysis revealed that the lemA and gacA genes were required for the full expression of a DNA binding activity. Images PMID:8002569

  17. Activated carbon based technology for the control of mercury emission from coal-fired power plants

    SciTech Connect

    Liu, W.; Vidic, R.D.; Kuemmel, R.; Fahlenkamp, H.

    1999-07-01

    The dynamics of sulfur-impregnated granular activated carbon (GAC) adsorbers for the uptake of vapor-phase mercury was evaluated as a function of key operating conditions. The effect of the sulfur impregnation method on mercury removal efficiency was examined through experiments conducted on commercially available sulfur-impregnated carbon (HGR) and carbon impregnated with sulfur in their laboratory (BPL-S). Although HGR and BPL-S possess similar sulfur contents, BLP-S is impregnated at a higher temperature which promotes a more uniform distribution of sulfur in the GAC pore structure. At low temperatures, HGR and BPL-S performed similarly in the removal of mercury vapor. However, as the temperature was increased above the melting point of sulfur, the performance of HGT deteriorated significantly, while the performance of BPL-S slightly improved. Temperature and the initial sulfur to carbon ratio (SCR) during production of BPL-S were the two control parameters for the impregnation procedure. The results showed that carbons impregnated with sulfur at higher temperatures exhibited higher efficiency for mercury removal and that the impregnation temperature is the most important factor influencing the efficiency of these sorbents for mercury uptake.

  18. The Two-Component Regulators GacS and GacA Positively Regulate a Nonfluorescent Siderophore through the Gac/Rsm Signaling Cascade in High-Siderophore-Yielding Pseudomonas sp. Strain HYS

    PubMed Central

    Yu, Xinyan; Chen, Min; Jiang, Zhen; Hu, Yi

    2014-01-01

    Siderophores, which are produced to overcome iron deficiency, are believed to be closely related to the adaptability of bacteria. The high-siderophore-yielding Pseudomonas sp. strain HYS simultaneously secretes the fluorescent siderophore pyoverdine and another nonfluorescent siderophore that is a major contributor to the high siderophore yield. Transposon mutagenesis revealed siderophore-related genes, including the two-component regulators GacS/GacA and a special cluster containing four open reading frames (the nfs cluster). Deletion mutations of these genes abolished nonfluorescent-siderophore production, and expression of the nfs cluster depended on gacA, indicating that gacS-gacA may control the nonfluorescent siderophore through regulation of the nfs cluster. Furthermore, regulation of the nonfluorescent siderophore by GacS/GacA involved the Gac/Rsm pathway. In contrast, inactivation of GacS/GacA led to upregulation of the fluorescent pyoverdine. The two siderophores were secreted under different iron conditions, probably because of differential effects of GacS/GacA. The global GacS/GacA regulatory system may control iron uptake by modulating siderophore production and may enable bacteria to adapt to changing iron environments. PMID:24982309

  19. The two-component regulators GacS and GacA positively regulate a nonfluorescent siderophore through the Gac/Rsm signaling cascade in high-siderophore-yielding Pseudomonas sp. strain HYS.

    PubMed

    Yu, Xinyan; Chen, Min; Jiang, Zhen; Hu, Yi; Xie, Zhixiong

    2014-09-01

    Siderophores, which are produced to overcome iron deficiency, are believed to be closely related to the adaptability of bacteria. The high-siderophore-yielding Pseudomonas sp. strain HYS simultaneously secretes the fluorescent siderophore pyoverdine and another nonfluorescent siderophore that is a major contributor to the high siderophore yield. Transposon mutagenesis revealed siderophore-related genes, including the two-component regulators GacS/GacA and a special cluster containing four open reading frames (the nfs cluster). Deletion mutations of these genes abolished nonfluorescent-siderophore production, and expression of the nfs cluster depended on gacA, indicating that gacS-gacA may control the nonfluorescent siderophore through regulation of the nfs cluster. Furthermore, regulation of the nonfluorescent siderophore by GacS/GacA involved the Gac/Rsm pathway. In contrast, inactivation of GacS/GacA led to upregulation of the fluorescent pyoverdine. The two siderophores were secreted under different iron conditions, probably because of differential effects of GacS/GacA. The global GacS/GacA regulatory system may control iron uptake by modulating siderophore production and may enable bacteria to adapt to changing iron environments. PMID:24982309

  20. In-place electrically heated regeneration of vapor-phase activated carbon. Final report, 11 July 1989-11 April 1990

    SciTech Connect

    Levy, R.; Hicks, R.E.; Gold, H.

    1990-09-01

    The Air Force is using the air stripping process to remove a variety of volatile organic contaminants from groundwater. Vapor-phase granular activated carbon (GAC) has proven successful in treating the contaminated air stream emanating from air stripping columns. but conventional regeneration methods are expensive, require transfer of the carbon. and degrade the carbon. The objective of this experimental program was to determine the feasibility of using electrically-heated processes for the in-place regeneration of vapor-phase GAC. Two processes were considered, namely microwave heating and electric resistance heating using the carbon itself as the resistance. The microwave heating equipment used gave nonuniform heating over the length of the carbon column and was not pursued further. Electric resistance, or Rintoul, heating is a commercially proven process that has been applied to the high-temperature regeneration of liquid-phase GAC in special purpose furnaces. The experimental program demonstrated that the Rintoul process can be efficiently applied to low-temperature, low energy, in-place regeneration of vapor-phase GAO. Repeated loading and regeneration of the carbon column showed no loss of adsorption capacity. Two methods of collecting TCE in a concentrated form were also successfully tested. Both processes involved recovery of the TCE in a condensate.

  1. 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.

  2. Effects of high salinity and constituent organic compounds on treatment of photo-processing waste by a sulfur-oxidizing bacteria/granular activated carbon sludge system.

    PubMed

    Lin, Bin-Le; Hosomi, Masaaki; Murakami, Akihiko

    2002-02-01

    To achieve practical treatment of photo-processing waste (PW) using our previously proposed sulfur-oxidizing bacteria (SOB)/granular activated carbon (GAC) sludge system, this paper elucidates why 3- to 5-X dilution of PW was required. That is, a series of experiments were carried out to show the effects of high salinity and constituent organic compounds in PW, respectively. Both an inorganic salts system and calcination PW system showed that SOB completely oxidizes S2O(3)2- -S to SO(4)2- -S even at 12.3 or 13.6% salinity, respectively; hence the dilution requirement is not attributable to high salinity. In experiments employing SOB and SOB/GAC systems to investigate the effects of 23 constituent compounds in PW, compounds were classified into Groups I, II, IIIa, and IIIb. Even with 10 g/l GAC, the nine compounds in Group IIIb still exhibited a toxic effect on SOB activity at 1- and 3-X dilutions; thus it is these compounds that are responsible for requiring dilution of PW. Accordingly, a reduction in their use within the photodeveloping and fix-stabilizing industry, and/or use of > 10g/l GAC, are new considerations for establishing a more practical PW treatment process.

  3. Adsorption of Selected Pharmaceutical Compounds onto Activated Carbon in Dilute Aqueous Solutions Exemplified by Acetaminophen, Diclofenac, and Sulfamethoxazole

    PubMed Central

    Chang, E.-E.; Wan, Jan-Chi; Liang, Chung-Huei; Dai, Yung-Dun; Chiang, Pen-Chi

    2015-01-01

    The adsorption of three pharmaceuticals, namely, acetaminophen, diclofenac, and sulfamethoxazole onto granular activated carbon (GAC), was investigated. To study competitive adsorption, both dynamic and steady-state adsorption experiments were conducted by careful selection of pharmaceuticals with various affinities and molecular size. The effective diffusion coefficient of the adsorbate was increased with decease in particle size of GAC. The adsorption affinity represented as Langmuir was consistent with the ranking of the octanol-water partition coefficient, Kow. The adsorption behavior in binary or tertiary systems could be described by competition adsorption. In the binary system adsorption replacement occurred, under which the adsorbate with the smaller Kow was replaced by the one with larger Kow. Results also indicated that portion of the micropores could be occupied only by the small target compound, but not the larger adsorbates. In multiple-component systems the competition adsorption might significantly be affected by the macropores and less by the meso- or micropores. PMID:26078989

  4. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics

    SciTech Connect

    Yu, Z.; Peldszus, S.; Huck, P.M.

    2009-03-01

    The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC) namely coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevant for drinking water treatment. Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns for the change in Freundlich KF and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated that film diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional mass transfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model. 32 refs., 3 figs., 2 tabs.

  5. Effects of ultrasonic pretreatment on quantity and composition of bacterial DNA recovered from granular activated carbon used for drinking water treatment.

    PubMed

    Kim, Tae Gwan; Kim, Sun-Hye; Cho, Kyung-Suk

    2014-01-01

    Effects of ultrasonic pretreatment on bacterial DNA recovery from granular activated carbon (GAC) were investigated. GAC (Calgon F400), biologically activated, was sampled from an actual drinking water plant. Different ultrasonic energy densities (0-400 J·cm(-3)) were applied with agitation (250 rpm for 30 min), and recovered bacterial DNA was quantified using quantitative PCR. Energy density was linearly correlated with the concentration of carbon fines produced from GAC during ultrasonication. Ultrasonication alone had no effect on DNA recovery at ≤60 J·cm(-3), but a strongly adverse effect at >67 J·cm(-3) due to the produced carbon fines. Agitation along with ultrasonication strongly enhanced the bacterial DNA recovery when ≤40 J·cm(-3) was applied, although it did not affect the production of carbon fines. Ribosomal tag pyrosequencing was used to compare recovered bacterial communities (0, 20 and 30 J·cm(-3) with or without agitation). Ultrasonication allowed for obtaining a more diverse and richer bacterial community from GAC, compared with the control. Agitation did not show a positive effect on community organization (richness and diversity). Consistently, canonical correspondence analysis indicated that the energy density was associated with the relative abundances of particular bacterial members (P < 0.05), while agitation did not. Correspondence analysis revealed that the recovered bacterial communities were grouped according to the applied energy densities. In conclusion, ultrasonication and agitation influence the recovered DNA in quality and quantity, respectively, and carbon fines as a by-product by ultrasonication interfere with the DNA recovery.

  6. Adsorption of phenolics on activated carbon--impact of pore size and molecular oxygen.

    PubMed

    Lu, Qiuli; Sorial, George A

    2004-05-01

    The impact of pore size of activated carbon fibers (ACFs) on adsorption capacity and on the potential for oligomerization of phenolic compounds on the surface of ACFs in the presence of molecular oxygen has been investigated in this study. Compared with granular activated carbon (GAC), ACFs have unique pore size distributions, suitable to be used to elucidate the effect of pore structure on adsorption. Adsorption isotherm data were collected for o-cresol and 2-ethylphenol on four ACFs (ACC-10, ACC-15, ACC-20, and ACC-25) with different micropore volumes and BET surface area and on one type of GAC bituminous base. These isotherms were collected under anoxic (absence of molecular oxygen) and oxic (presence of molecular oxygen) conditions. No significant impact of the presence of molecular oxygen on adsorption capacity was noted for ACC-10. ACC-10 has an average pore width of 19.2 A and total pore volume of 0.43 cm3g(-1). On the other hand, for the remaining ACFs, which have larger average pore width and larger pore volume, significant increase in the adsorptive capacity had been observed when molecular oxygen was present. The GAC gave the greatest difference between anoxic and oxic conditions when compared to all the ACFs studied. Binary adsorption of o-cresol and 2-ethylphenol on ACFs with the least pore size (ACC-10) also showed no significant differences between oxic and anoxic environment. The binary system under both anoxic and oxic conditions was well predicted by the ideal adsorbed solution theory (IAST).

  7. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  8. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

    NASA Astrophysics Data System (ADS)

    Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

    2012-07-01

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  9. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  10. Characterization of the gacA-dependent surface and coral mucus colonization by an opportunistic coral pathogen Serratia marcescens PDL100.

    PubMed

    Krediet, Cory J; Carpinone, Emily M; Ritchie, Kim B; Teplitski, Max

    2013-05-01

    Opportunistic pathogens rely on global regulatory systems to assess the environment and to control virulence and metabolism to overcome host defenses and outcompete host-associated microbiota. In Gammaproteobacteria, GacS/GacA is one such regulatory system. GacA orthologs direct the expression of the csr (rsm) small regulatory RNAs, which through their interaction with the RNA-binding protein CsrA (RsmA), control genes with functions in carbon metabolism, motility, biofilm formation, and virulence. The csrB gene was controlled by gacA in Serratia marcescens PDL100. A disruption of the S. marcescens gacA gene resulted in an increased fitness of the mutant on mucus of the host coral Acropora palmata and its high molecular weight fraction, whereas the mutant was as competitive as the wild type on the low molecular weight fraction of the mucus. Swarming motility and biofilm formation were reduced in the gacA mutant. This indicates a critical role for gacA in the efficient utilization of specific components of coral mucus and establishment within the surface mucopolysaccharide layer. While significantly affecting early colonization behaviors (coral mucus utilization, swarming motility, and biofilm formation), gacA was not required for virulence of S. marcescens PDL100 in either a model polyp Aiptasia pallida or in brine shrimp Artemia nauplii.

  11. Effect of activated carbon amendment on bacterial community structure and functions in a PAH impacted urban soil.

    PubMed

    Meynet, Paola; Hale, Sarah E; Davenport, Russell J; Cornelissen, Gerard; Breedveld, Gijs D; Werner, David

    2012-05-01

    We collected urban soil samples impacted by polycyclic aromatic hydrocarbons (PAHs) from a sorbent-based remediation field trial to address concerns about unwanted side-effects of 2% powdered (PAC) or granular (GAC) activated carbon amendment on soil microbiology and pollutant biodegradation. After three years, total microbial cell counts and respiration rates were highest in the GAC amended soil. The predominant bacterial community structure derived from denaturing gradient gel electrophoresis (DGGE) shifted more strongly with time than in response to AC amendment. DGGE band sequencing revealed the presence of taxa with closest affiliations either to known PAH degraders, e.g. Rhodococcus jostii RHA-1, or taxa known to harbor PAH degraders, e.g. Rhodococcus erythropolis, in all soils. Quantification by real-time polymerase chain reaction yielded similar dioxygenases gene copy numbers in unamended, PAC-, or GAC-amended soil. PAH availability assessments in batch tests showed the greatest difference of 75% with and without biocide addition for unamended soil, while the lowest PAH availability overall was measured in PAC-amended, live soil. We conclude that AC had no detrimental effects on soil microbiology, AC-amended soils retained the potential to biodegrade PAHs, but the removal of available pollutants by biodegradation was most notable in unamended soil. PMID:22455603

  12. Effect of Activated Carbon Amendment on Bacterial Community Structure and Functions in a PAH Impacted Urban Soil

    PubMed Central

    2012-01-01

    We collected urban soil samples impacted by polycyclic aromatic hydrocarbons (PAHs) from a sorbent-based remediation field trial to address concerns about unwanted side-effects of 2% powdered (PAC) or granular (GAC) activated carbon amendment on soil microbiology and pollutant biodegradation. After three years, total microbial cell counts and respiration rates were highest in the GAC amended soil. The predominant bacterial community structure derived from denaturing gradient gel electrophoresis (DGGE) shifted more strongly with time than in response to AC amendment. DGGE band sequencing revealed the presence of taxa with closest affiliations either to known PAH degraders, e.g. Rhodococcus jostii RHA-1, or taxa known to harbor PAH degraders, e.g. Rhodococcus erythropolis, in all soils. Quantification by real-time polymerase chain reaction yielded similar dioxygenases gene copy numbers in unamended, PAC-, or GAC-amended soil. PAH availability assessments in batch tests showed the greatest difference of 75% with and without biocide addition for unamended soil, while the lowest PAH availability overall was measured in PAC-amended, live soil. We conclude that AC had no detrimental effects on soil microbiology, AC-amended soils retained the potential to biodegrade PAHs, but the removal of available pollutants by biodegradation was most notable in unamended soil. PMID:22455603

  13. Equilibrium and column adsorption studies of 2,4-dinitroanisole (DNAN) on surface modified granular activated carbons.

    PubMed

    Boddu, V M; Abburi, K; Fredricksen, A J; Maloney, S W; Damavarapu, R

    2009-02-01

    2,4-Dinitroanisole (DNAN) is used as a component extensively in the development of insensitive munitions. This may result in release of DNAN into the environment. Here, the results are reported of a study on the removal characteristics of DNAN through adsorption on granular activated carbon (GAC), chitosan coated granular activated carbon (CGAC), acid treated granular activated carbon (AGAC) and alkali treated granular activated carbon (BGAC) under equilibrium and column flow conditions. The effect of pH, contact time, concentration of DNAN, and presence of electrolytes on the uptake of DNAN by the adsorbents was investigated. The equilibrium data were fitted to different types of adsorption isotherms. The data were further analysed on the basis of Lagergren first-order, pseudo second-order and intraparticle diffusion kinetic models. Breakthrough curves were obtained based on column flow results. All the adsorbents were capable of removing about 99% of DNAN from aqueous media, except CGAC which adsorbed about 87% of DNAN.

  14. Sorption and degradation of petroleum hydrocarbons, polycyclic aromatic hydrocarbons, alkylphenols, bisphenol A and phthalates in landfill leachate using sand, activated carbon and peat filters.

    PubMed

    Kalmykova, Yuliya; Moona, Nashita; Strömvall, Ann-Margret; Björklund, Karin

    2014-06-01

    Landfill leachates are repeatedly found contaminated with organic pollutants, such as alkylphenols (APs), phthalates and polycyclic aromatic hydrocarbons (PAHs) at levels exceeding water quality standards. It has been shown that these pollutants may be present in the colloidal and truly dissolved phase in contaminated water, making particle separation an inefficient removal method. The aim of this study was to investigate sorption and degradation of petroleum hydrocarbons (PHCs), selected APs, bisphenol A (BPA), phthalates and PAHs from landfill leachate using sand, granulated activated carbon (GAC) and peat moss filters. A pilot plant was installed at an inactive landfill with mixed industrial and household waste and samples were collected before and after each filter during two years. Leachate pre-treated in oil separator and sedimentation pond failed to meet water quality standards in most samples and little improvement was seen after the sand filter. These techniques are based on particle removal, whereas the analysed pollutants are found, to varying degrees, bound to colloids or dissolved. However, even highly hydrophobic compounds expected to be particle-bound, such as the PHCs and high-molecular weight PAHs, were poorly removed in the sand filter. The APs and BPA were completely removed by the GAC filter, while mass balance calculations indicate that 50-80% of the investigated phenols were removed in the peat filter. Results suggest possible AP degradation in peat filters. No evidence of phthalate degradation in the landfill, pond or the filters was found. The PHCs were completely removed in 50% and 35% of the measured occasions in the GAC and peat filters, respectively. The opposite trend was seen for removal of PAHs in GAC (50%) and peat (63%). Oxygenated PAHs with high toxicity were found in the leachates but not in the pond sediment. These compounds are likely formed in the pond water, which is alarming because sedimentation ponds are commonly used

  15. 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).

  16. 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

  17. Effect of humic acid on pyrene removal from water by polycation-clay mineral composites and activated carbon.

    PubMed

    Radian, Adi; Mishael, Yael

    2012-06-01

    Pyrene removal by polycation-montmorillonite (MMT) composites and granulated activated carbon (GAC) in the presence of humic acid (HA) was examined. Pyrene, HA, and sorbent interactions were characterized by FTIR, fluorescence and zeta measurements, adsorption, and column filtration experiments. Pyrene binding coefficients to the macromolecules were in the order of PVPcoS (poly-4-vinylpiridine-co-styrene) > HA > PDADMAC (poly diallyl-dimethyl-ammonium-chloride), correlating to pyrene-macromolecules compatibility. Electrostatic interactions explained the high adsorption of HA to both composites (∼100%), whereas HA adsorption by GAC was low. Pyrene removal by the composites, unlike GAC, was enhanced in the presence of HA; removal by PDADMAC-MMT increased from ∼50 (k(d) = 2.2 × 10(3) kg/L) to ∼70% (k(d) = 2.4 × 10(3) kg/L) in the presence of HA. This improvement was attributed to the adsorption of pyrene-HA complexes. PVPcoS-MMT was most efficient in removing pyrene (k(d) = 1.1 × 10(4) kg/L, >95% removal) which was explained in terms of specific π donor-π acceptor interactions. Pyrene uptake by column filters of GAC reached ∼50% and decreased to ∼30% in the presence of HA. Pyrene removal by the PVPcoS-MMT filter was significantly higher (100-85% removal), exhibiting only a small decrease in the presence of HA. The utilization of HA as an enhancing agent in pollutant removal is novel and of major importance in water treatment. PMID:22545663

  18. Role of predation by zooplankton in transport and fate of protozoan (oo)cysts in granular activated carbon filtration.

    PubMed

    Bichai, Françoise; Barbeau, Benoit; Dullemont, Yolanda; Hijnen, Wim

    2010-02-01

    The significance of zooplankton in the transport and fate of pathogenic organisms in drinking water is poorly understood, although many hints of the role of predation in the persistence of microorganisms through water treatment processes can be found in literature. The objective of this study was to assess the impact of predation by natural zooplankton on the transport and fate of protozoan (oo)cysts in granular activated carbon (GAC) filtration process. UV-irradiated unlabelled Cryptosporidium parvum and Giardia lamblia (oo)cysts were seeded into two pilot-scale GAC filtration columns operated under full-scale conditions. In a two-week period after seeding, a reduction of free (oo)cysts retained in the filter bed was observed. Zooplankton was isolated from the filter bed and effluent water on a 30 microm net before and during the two-week period after seeding; it was enumerated and identified. Rotifers, which are potential predators of (oo)cysts, accounted for the major part of the isolated zooplankton. Analytical methods were developed to detect (oo)cysts internalized in natural zooplankton isolated from the filter bed and effluent water. Sample sonication was optimized to disrupt zooplankton organisms and release internalized microorganisms. (Oo)cysts released from zooplankton after sonication were isolated by IMS and stained (EasyStain) for microscopic counting. Both Cryptosporidium and Giardia (oo)cysts were detected in association with zooplankton in the filter bed samples as well as in the effluent of GAC filters. The results of this study suggest that predation by zooplankton can play a role in the remobilization of persistent pathogens such as Cryptosporidium and Giardia (oo)cysts retained in GAC filter beds, and consequently in the transmission of these pathogens in drinking water.

  19. Investigation of decolorization of textile wastewater in an anaerobic/aerobic biological activated carbon system (A/A BAC).

    PubMed

    Pasukphun, N; Vinitnantharat, S; Gheewala, S

    2010-04-01

    The aim of this study is to investigate the decolorization in anaerobic/aerobic biological activated carbon (A/A BAC) system. The experiment was divided into 2 stages; stage I is batch test for preliminary study of dye removal equilibrium time. The preliminary experiment (stage I) provided the optimal data for experimental design of A/A BAC system in SBR (stage II). Stage II is A/A BAC system imitated Sequencing Batch Reactor (SBR) which consist of 5 main periods; fill, react, settle, draw and idle. React period include anaerobic phase followed by aerobic phase. The BAC main media; Granular Activated Carbon (GAC), Mixed Cultures (MC) and Biological Activated Carbon (BAC) were used for dye and organic substances removal in three different solutions; Desizing Agent Solution (DAS), dye Solution (DS) and Synthetic Textile Wastewater (STW). Results indicate that GAC adsorption plays role in dye removal followed by BAC and MC activities, respectively. In the presence desizing agent, decolorization by MC was improved because desizing agent acts as co-substrates for microorganisms. It was found that 50% of dye removal efficiency was achieved in Fill period by MC. GC/MS analysis was used to identify dye intermediate from decolorization. Dye intermediate containing amine group was found in the solution and on BAC surfaces. The results demonstrated that combination of MC and BAC in the system promotes decolorization and dye intermediate removal. In order to improve dye removal efficiency in an A/A BAC system, replacement of virgin GAC, sufficient co-substrates supply and the appropriate anaerobic: aerobic period should be considered.

  20. Dewatering Peat With Activated Carbon

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1984-01-01

    Proposed process produces enough gas and carbon to sustain itself. In proposed process peat slurry is dewatered to approximately 40 percent moisture content by mixing slurry with activated carbon and filtering with solid/liquid separation techniques.

  1. Effect of pH, empty bed contact time and hydraulic loading rate on lead removal by granular activated carbon columns

    SciTech Connect

    Reed, B.E.; Jamil, M.; Thomas, B.

    1996-07-01

    Batch and column studies were performed to determine the effect of pH, empty bed contact time (EBCT), and hydraulic loading rate (HLR) on lead removal by granular activated carbon (GAC) columns. Lead removal increased with increasing pH, and for the majority of the adsorbate:adsorbent ratios investigated, was 100% as pHs < pH{sub prec}. Column pH was extremely important to lead removal in GAC columns. A simple acid-base regeneration procedure was found to be effective in desorbing/resolubilizing the carbon-bound lead and raising the pH for the subsequent treatment run. Regeneration efficiencies were often less than 100%, but column performance was not adversely affected. For 1 mg/L lead, the optimum EBCT was between 6 and 7 minutes, Whereas for 10 mg/L lead it was less than 10 minutes. The effect of HLR (4.9 and 9.8 m/hr) on column performance was minimal for 1 mg/L lead, whereas at 10 mg/L lead column removal was slightly better at the higher HLR. Carbon usage rates were higher than those observed for wastewaters containing organic contaminants, especially at 10 mg/L lead. However, given the relatively simple regeneration scheme, the applicability of GAC columns for metal-bearing wastewaters appears to be technically feasible. 8 refs., 7 figs., 3 tabs.

  2. 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).

  3. A comparative study of coagulation, granular- and powdered-activated carbon for the removal of perfluorooctane sulfonate and perfluorooctanoate in drinking water treatment.

    PubMed

    Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Suja, Fatihah

    2015-01-01

    Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are persistent organic pollutants in the environment and their occurrence causes toxicological effects on humans. We examined different conventional coagulant treatments such as alum, ferric chloride and polyaluminium chloride in removing these compounds. These were then compared with a natural coagulant (Moringa oleifera). We also investigated the powdered-activated carbon (PAC) and granular-activated carbon (GAC) for removing these compounds. At an initial dose of 5 mg/L, polyaluminium chloride led to a higher reduction of PFOS/PFOA compared with alum which in turn was higher than ferric. The removal efficiency increased with the increase in coagulant dose and decrease in pH. M. oleifera was very effective in reducing PFOS and PFOA than conventional coagulants, with a reduction efficiencies of 65% and 72%, respectively, at a dose of 30 mg/L. Both PAC and GAC were very effective in reducing these compounds than coagulations. PAC led to a higher reduction in PFOS and PFOA than GAC due to its greater surface area and shorter internal diffusion distances. The addition of PAC (10 min contact time) with coagulation (at 5 mg/L dosage) significantly increased the removal efficiency, and the maximum removal efficiency was for M. oleifera with 98% and 94% for PFOS and PFOA, respectively. The reduction efficiency of PFOS/PFOA was reduced with the increase in dissolved organic concentration due to the adsorption competition between organic molecules and PFOS/PFOA. PMID:25860623

  4. A comparative study of coagulation, granular- and powdered-activated carbon for the removal of perfluorooctane sulfonate and perfluorooctanoate in drinking water treatment.

    PubMed

    Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Suja, Fatihah

    2015-01-01

    Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are persistent organic pollutants in the environment and their occurrence causes toxicological effects on humans. We examined different conventional coagulant treatments such as alum, ferric chloride and polyaluminium chloride in removing these compounds. These were then compared with a natural coagulant (Moringa oleifera). We also investigated the powdered-activated carbon (PAC) and granular-activated carbon (GAC) for removing these compounds. At an initial dose of 5 mg/L, polyaluminium chloride led to a higher reduction of PFOS/PFOA compared with alum which in turn was higher than ferric. The removal efficiency increased with the increase in coagulant dose and decrease in pH. M. oleifera was very effective in reducing PFOS and PFOA than conventional coagulants, with a reduction efficiencies of 65% and 72%, respectively, at a dose of 30 mg/L. Both PAC and GAC were very effective in reducing these compounds than coagulations. PAC led to a higher reduction in PFOS and PFOA than GAC due to its greater surface area and shorter internal diffusion distances. The addition of PAC (10 min contact time) with coagulation (at 5 mg/L dosage) significantly increased the removal efficiency, and the maximum removal efficiency was for M. oleifera with 98% and 94% for PFOS and PFOA, respectively. The reduction efficiency of PFOS/PFOA was reduced with the increase in dissolved organic concentration due to the adsorption competition between organic molecules and PFOS/PFOA.

  5. Ciprofloxacin adsorption on graphene and granular activated carbon: kinetics, isotherms, and effects of solution chemistry.

    PubMed

    Zhu, Xuan; Tsang, Daniel C W; Chen, Feng; Li, Shiyu; Yang, Xin

    2015-01-01

    Ciprofloxacin (CIP) is a commonly used antibiotic and widely detected in wastewaters and farmlands nowadays. This study evaluated the efficacy of next-generation adsorbent (graphene) and conventional adsorbent (granular activated carbon, GAC) for CIP removal. Batch experiments and characterization tests were conducted to investigate the adsorption kinetics, equilibrium isotherms, thermodynamic properties, and the influences of solution chemistry (pH, ionic strength, natural organic matter (NOM), and water sources). Compared to GAC, graphene showed significantly faster adsorption and reached equilibrium within 3 min, confirming the rapid access of CIP into the macroporous network of high surface area of graphene as revealed by the Brunner-Emmet-Teller measurements analysis. The kinetics was better described by a pseudo-second-order model, suggesting the importance of the initial CIP concentration related to surface site availability of graphene. The adsorption isotherm on graphene followed Langmuir model with a maximum adsorption capacity of 323 mg/g, which was higher than other reported carbonaceous adsorbents. The CIP adsorption was thermodynamically favourable on graphene and primarily occurred through π - π interaction, according to the FTIR spectroscopy. While the adsorption capacity of graphene decreased with increasing solution pH due to the speciation change of CIP, the adverse effects of ionic strength (0.01-0.5 mol L(-1)), presence of NOM (5 mg L⁻¹), and different water sources (river water or drinking water) were less significant on graphene than GAC. These results indicated that graphene can serve as an alternative adsorbent for CIP removal in commonly encountered field conditions, if proper separation and recovery is available in place. PMID:26050736

  6. Genetic and phenotypic analysis of the GacS/GacA system in the moderate halophile Halomonas anticariensis.

    PubMed

    Tahrioui, Ali; Quesada, Emilia; Llamas, Inmaculada

    2013-03-01

    A multisensory, hybrid histidine kinase (HK) and a response regulator (RR), which together may well constitute a two-component regulatory system (TCS), have been located in Halomonas anticariensis FP35(T) by transposon mutagenesis. This TCS is homologous to the GacS/GacA system described for many Gram-negative bacteria. An analysis of crude N-acylhomoserine lactone (AHL) extracts from cultures of FP35gacS and FP35gacA mutants showed that they produced lower quantities of AHLs than the wild-type strain. In addition, RT-PCR analysis revealed a considerable decrease in the expression of the quorum-sensing (QS) genes hanR and hanI compared with the wild-type strain. This result indicates that the GacS/GacA TCS exerts a positive effect upon the QS HanR/HanI system and suggests its integral involvement in the intercellular communication strategies of this bacterium. We have also demonstrated the influence of GacS and GacA upon exopolysaccharide production and biofilm formation, in which this regulatory machinery appears to play a key role in an overall system that co-ordinates gene expression and behaviour in H. anticariensis FP35(T) in response to environmental conditions.

  7. Granular activated carbon pilot treatment studies for explosives removal from contaminated groundwater

    SciTech Connect

    Wujcik, W.J.; Lowe, W.L.; Marks, P.J. ); Sisk, W.E. )

    1992-08-01

    Manufacturing activities at Army Ammunition Plants (AAPs) result in the production of organic wastewaters that contain both explosive residues and other organic chemicals. As a result of past waste practices at such plants, explosive residues may leach through the soil and contaminate groundwater. Two pilot studies were performed to evaluate the use of granular activated carbon (GAC) to treat groundwater contaminated with explosives at Badger AAP and Milan AAP. An additional goal of the Badger AAP study was to examine the potential discharge of explosives 2,4-DNT and 2,6-DNT from a packed column air stripper used to remove volatile organic compounds from groundwater. A laboratory method was developed for the BAAP study to permit lower detection levels for 2,4-DNT and 2,6-DNT (0.46[mu]g/L and 0.017 [mu]g/L, respectively). The studies concluded that removal of explosives from groundwater using continuous flow GAC is feasible. 14 refs., 10 figs., 11 tabs.

  8. Global control of GacA in secondary metabolism, primary metabolism, secretion systems, and motility in the rhizobacterium Pseudomonas aeruginosa M18.

    PubMed

    Wei, Xue; Huang, Xianqing; Tang, Lulu; Wu, Daqiang; Xu, Yuquan

    2013-08-01

    The rhizobacterium Pseudomonas aeruginosa M18 can produce a broad spectrum of secondary metabolites, including the antibiotics pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA), hydrogen cyanide, and the siderophores pyoverdine and pyochelin. The antibiotic biosynthesis of M18 is coordinately controlled by multiple distinct regulatory pathways, of which the GacS/GacA system activates Plt biosynthesis but strongly downregulates PCA biosynthesis. Here, we investigated the global influence of a gacA mutation on the M18 transcriptome and related metabolic and physiological processes. Transcriptome profiling revealed that the transcript levels of 839 genes, which account for approximately 15% of the annotated genes in the M18 genome, were significantly influenced by the gacA mutation during the early stationary growth phase of M18. Most secondary metabolic gene clusters, such as pvd, pch, plt, amb, and hcn, were activated by GacA. The GacA regulon also included genes encoding extracellular enzymes and cytochrome oxidases. Interestingly, the primary metabolism involved in the assimilation and metabolism of phosphorus, sulfur, and nitrogen sources was also notably regulated by GacA. Another important category of the GacA regulon was secretion systems, including H1, H2, and H3 (type VI secretion systems [T6SSs]), Hxc (T2SS), and Has and Apr (T1SSs), and CupE and Tad pili. More remarkably, GacA inhibited swimming, swarming, and twitching motilities. Taken together, the Gac-initiated global regulation, which was mostly mediated through multiple regulatory systems or factors, was mainly involved in secondary and primary metabolism, secretion systems, motility, etc., contributing to ecological or nutritional competence, ion homeostasis, and biocontrol in M18. PMID:23708134

  9. A comparative study on the efficiency of ozonation and coagulation-flocculation as pretreatment to activated carbon adsorption of biologically stabilized landfill leachate.

    PubMed

    Oloibiri, Violet; Ufomba, Innocent; Chys, Michael; Audenaert, Wim T M; Demeestere, Kristof; Van Hulle, Stijn W H

    2015-09-01

    The present work investigates the potential of coagulation-flocculation and ozonation to pretreat biologically stabilized landfill leachate before granular activated carbon (GAC) adsorption. Both iron (III) chloride (FeCl3) and polyaluminium chloride (PACl) are investigated as coagulants. Better organic matter removal is observed when leachate was treated with FeCl3. At a dose of 1mg FeCl3/mg CODo (CODo: initial COD content), the COD and α254 removal was 66% and 88%, respectively. Dosing 1mg PACl/mg CODo resulted in 44% COD and 72% α254 removal. The settle-ability of sludge generated by PACl leveled off at 252mL/g, while a better settle-ability of 154mL/g was obtained for FeCl3 after dosing 1mg coagulant/mg CODo. For ozonation, the percentage of COD and α254 removal increased as the initial COD concentration decreased. Respectively 44% COD and 77% α254 removal was observed at 112mg COD/L compared to 5% COD and 26% α254 removal at 1846mg COD/L. Subsequent activated carbon adsorption of ozonated, coagulated and untreated leachate resulted in 77%, 53% and 8% total COD removal after treatment of 6 bed volumes. Clearly showing the benefit of treating the leachate before GAC adsorption. Mathematical modeling of the experimental GAC adsorption data with Thomas and Yoon-Nelson models show that ozonation increases the adsorption capacity and breakthrough time of GAC by a factor of 2.5 compared to coagulation-flocculation.

  10. In situ application of activated carbon and biochar to PCB-contaminated soil and the effects of mixing regime.

    PubMed

    Denyes, Mackenzie J; Rutter, Allison; Zeeb, Barbara A

    2013-11-01

    The in situ use of carbon amendments such as activated carbon (AC) and biochar to minimize the bioavailability of organic contaminants is gaining in popularity. In the first in situ experiment conducted at a Canadian PCB-contaminated Brownfield site, GAC and two types of biochar were statistically equal at reducing PCB uptake into plants. PCB concentrations in Cucurbita pepo root tissue were reduced by 74%, 72% and 64%, with the addition of 2.8% GAC, Burt's biochar and BlueLeaf biochar, respectively. A complementary greenhouse study which included a bioaccumulation study of Eisenia fetida (earthworm), found mechanically mixing carbon amendments with PCB-contaminated soil (i.e. 24 h at 30 rpm) resulted in shoot, root and worm PCB concentrations 66%, 59% and 39% lower than in the manually mixed treatments (i.e. with a spade and bucket). Therefore, studies which mechanically mix carbon amendments with contaminated soil may over-estimate the short-term potential to reduce PCB bioavailability.

  11. In situ application of activated carbon and biochar to PCB-contaminated soil and the effects of mixing regime.

    PubMed

    Denyes, Mackenzie J; Rutter, Allison; Zeeb, Barbara A

    2013-11-01

    The in situ use of carbon amendments such as activated carbon (AC) and biochar to minimize the bioavailability of organic contaminants is gaining in popularity. In the first in situ experiment conducted at a Canadian PCB-contaminated Brownfield site, GAC and two types of biochar were statistically equal at reducing PCB uptake into plants. PCB concentrations in Cucurbita pepo root tissue were reduced by 74%, 72% and 64%, with the addition of 2.8% GAC, Burt's biochar and BlueLeaf biochar, respectively. A complementary greenhouse study which included a bioaccumulation study of Eisenia fetida (earthworm), found mechanically mixing carbon amendments with PCB-contaminated soil (i.e. 24 h at 30 rpm) resulted in shoot, root and worm PCB concentrations 66%, 59% and 39% lower than in the manually mixed treatments (i.e. with a spade and bucket). Therefore, studies which mechanically mix carbon amendments with contaminated soil may over-estimate the short-term potential to reduce PCB bioavailability. PMID:23933124

  12. Application of sulfur impregnated activated carbons for the control of mercury emissions

    SciTech Connect

    Vidic, R.D.; Liu, W.; Brown, T.D.

    1998-12-31

    The dynamics of granular activated carbon (GAC) adsorbers for the uptake of vapor-phase mercury was evaluated as a function of temperature, influent mercury concentration, and empty bed contact time. Sulfur-impregnated carbons exhibited enhanced mercury removal efficiency over virgin carbon due to formation of mercuric sulfide on the carbon surface. The effect of the sulfur impregnation method on mercury removal efficiency was examined through experiments conducted on commercially available sulfur-impregnated carbon (HGR) and carbon impregnated with sulfur in the laboratory (BPL-S). Although HGR and BPL-S possess similar sulfur contents, BPL-S is impregnated at a higher temperature which promotes a more uniform distribution of sulfur in the GAC pore structure. At low influent mercury concentrations and low temperatures, HGR and BPL-S performed similarly in the removal of mercury vapor. However, as the temperature was increased above the melting point of sulfur, the performance of HGR deteriorated significantly, while the performance of BPL-S slightly improved. For both HGR and BPL-S, the observed dynamic mercury adsorptive capacities were far below the capacities predicted by the stoichiometry of mercuric sulfide formation. In HGR carbon the sulfur is very accessible, but agglomeration which occurs at high temperatures causes the sulfur to become relatively unreactive. In BPL-S carbon, on the other hand, the sulfur remains in a highly reactive form, but its location deep in the internal pores makes it relatively inaccessible and susceptible to blockage by HgS formation. Impregnation temperature and the initial sulfur to carbon ratio (SCR) during the impregnation are the two key control parameters for the preparation of these new (BPL-S) sorbents. Higher impregnation temperatures can significantly enhance mercury removal capacity for adsorbents derived either from virgin or re-generated activated carbons. Large fraction of active sulfur atoms that are created at

  13. Carotenoid pigments in GAC fruit (Momordica cochinchinensis SPRENG).

    PubMed

    Aoki, Hiromitsu; Kieu, Nguyen Thi Minh; Kuze, Noriko; Tomisaka, Kazue; Van Chuyen, Nguyen

    2002-11-01

    The carotenoids in Gac fruit (Momordica Cochinchinensis spreng) were analysed by high-performance liquid chromatography (HPLC), and the concentrations of beta-carotene, lycopene, zeaxanthin and beta-cryptoxanthin were measured. Lycopene was found to be predominantly present in the Gac seed membrane at a concentration of up to 380 microg/g of seed membrane. The concentration of lycopene in the Gac seed membrane was about ten-fold higher than that in known lycopene-rich fruit and vegetables, indicating that Gac fruit could be a new and potentially valuable source of lycopene. PMID:12506992

  14. Carotenoid pigments in GAC fruit (Momordica cochinchinensis SPRENG).

    PubMed

    Aoki, Hiromitsu; Kieu, Nguyen Thi Minh; Kuze, Noriko; Tomisaka, Kazue; Van Chuyen, Nguyen

    2002-11-01

    The carotenoids in Gac fruit (Momordica Cochinchinensis spreng) were analysed by high-performance liquid chromatography (HPLC), and the concentrations of beta-carotene, lycopene, zeaxanthin and beta-cryptoxanthin were measured. Lycopene was found to be predominantly present in the Gac seed membrane at a concentration of up to 380 microg/g of seed membrane. The concentration of lycopene in the Gac seed membrane was about ten-fold higher than that in known lycopene-rich fruit and vegetables, indicating that Gac fruit could be a new and potentially valuable source of lycopene.

  15. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbonGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  16. Removal of a wide range of emerging pollutants from wastewater treatment plant discharges by micro-grain activated carbon in fluidized bed as tertiary treatment at large pilot scale.

    PubMed

    Mailler, R; Gasperi, J; Coquet, Y; Buleté, A; Vulliet, E; Deshayes, S; Zedek, S; Mirande-Bret, C; Eudes, V; Bressy, A; Caupos, E; Moilleron, R; Chebbo, G; Rocher, V

    2016-01-15

    Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbonGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with μCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in μGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a μGAC retention time (SRT) of 90-100 days. The μGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the μGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for μGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92

  17. Effect of biological activated carbon pre-treatment to control organic fouling in the microfiltration of biologically treated secondary effluent.

    PubMed

    Pramanik, Biplob Kumar; Roddick, Felicity A; Fan, Linhua

    2014-10-15

    Biological activated carbon (BAC) filtration was investigated as a pre-treatment for reducing the organic fouling of a microfiltration membrane (0.1 μm polyvinylidene fluoride) in the treatment of a biologically treated secondary effluent (BTSE) from a municipal wastewater treatment plant. BAC treatment of the BTSE resulted in a marked improvement in permeate flux, which was attributed to the effective removal of organic foulants and particulates. Although the BAC removed significantly less dissolved organic carbon than the granular activated carbon (GAC) treatment which was used as a control for comparison, it led to a markedly greater flux. This was attributed to the effective removal of the very high molecular weight substances such as biopolymers by the BAC through biodegradation and adsorption of those molecules on the biofilm. Size exclusion chromatography showed the BAC treatment led to approximately 30% reduction in these substances, whereas the GAC did not greatly remove these molecules. The BAC treatment led to a greater reduction of loosely-attached and firmly-attached membrane surface foulant, and this was confirmed by attenuated total reflection-fourier transform infrared spectroscopy analysis. This study demonstrated the potential of BAC pre-treatment for reducing organic fouling and thus improving flux for the microfiltration of BTSE.

  18. Continuous cultivation of Arthrospira platensis using exhausted medium treated with granular activated carbon

    NASA Astrophysics Data System (ADS)

    Morocho-Jácome, Ana Lucía; Mascioli, Guilherme Favaro; Sato, Sunao; Carvalho, João Carlos Monteiro de

    2015-03-01

    Reusing culture medium of Arthrospira platensis is quite important in large scale production because its inappropriate disposal could exacerbate problems of environmental pollution. This study evaluates the suitability of using different quantities of exhausted Schlösser medium after continuous treatment using granular activated carbon (GAC) with a residence time (T) of 2 h for A. platensis growth in continuous cultivation. A tubular photobioreactor (PBR) and urea as cheap nitrogen source were used, taking as response variables kinetic parameters and biomass composition. The removal of both organic matter and pigment (OMR and PgR, respectively) was measured to evaluate the efficiency of the treatment process. This treatment process yielded high values of OMR (73.7 ± 0.1%) and PgR (52.4 ± 0.4%) using 75% treated medium, thereby A. platensis biomass with high protein content (42.0 ± 0.6%), 1568 ± 15 mg/L cell concentration under steady-state conditions and 941 mg/L d cell productivity. This alternative to simultaneous treatment with GAC for reuse of Schlösser medium in continuous cultivation could ensure no diminution in either cell productivity or protein content in A. platensis cultivation using tubular PBR with 65% reduction in medium culture costs.

  19. Adsorptive removal of aniline by granular activated carbon from aqueous solutions with catechol and resorcinol.

    PubMed

    Suresh, S; Srivastava, V C; Mishrab, I M

    2012-01-01

    In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C(0,i)) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature (T), adsorbent dosage (m) and contact time (t). The L27 orthogonal array consisting of five parameters each with three levels was used to determine the total amount of solutes adsorbed on GAC (q(tot), mmol/g) and the signal-to-noise ratio. The analysis of variance (ANOVA) was used to determine the optimum conditions. Under these conditions, the ANOVA shows that m is the most important parameter in the adsorption process. The most favourable levels of process parameters were T = 303 K, m = 10 g/l and t = 660 min for both the systems, qtot values in the confirmation experiments carried out at optimum conditions were 0.73 and 0.95 mmol/g for aniline-catechol and aniline-resorcinol systems, respectively.

  20. Zinc-sulphate-heptahydrate coated activated carbon for microbe removal from stormwater.

    PubMed

    Guest, R M; Schang, C; Deletic, A; McCarthy, D T

    2012-01-01

    There is a need to develop effective stormwater filters for passive (without any addition of chemicals or energy) and effective removal of pathogens in order to mainstream stormwater harvesting. This study focuses on the development of coated granular activated carbon (GAC) filtration material in order to develop filters for effective removal of pathogens from urban stormwater. Several laboratory trials were performed to gauge the effectiveness of the filters, which use a mixture of the zinc-sulphate-heptahydrate coated GAC and sand, on the removal of Escherichia coli (E. coli) from semi-natural stormwater. On average, a 98% removal of the inflow concentration of E. coli was achieved. Furthermore, there was also an improvement of approximately 25% in the removal of phosphorous. However, it was found that the treated material was leaching zinc. It was important to determine whether the observed removal of E. coli was indirectly caused by the sampling methodology. The results showed that the inactivation of the E. coli in the collected sample was small compared with the inactivation which actually occurred within the filter. This provides much promise to the filter, but the presence of zinc in the outflow demonstrates the need for further investigation into the stabilisation of the coating process.

  1. 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

  2. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  3. Detection of hydroxyl radicals during regeneration of granular activated carbon in dielectric barrier discharge plasma system

    NASA Astrophysics Data System (ADS)

    Tang, Shoufeng; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-03-01

    To understand the reactions taking place in the dielectric barrier discharge (DBD) plasma system of activated carbon regeneration, the determination of active species is necessary. A method based on High Performance Liquid Chromatography with radical trapping by salicylic acid, has been developed to measure hydroxyl radical (•OH) in the DBD plasma reactor. The effects of applied voltage, treatment time, and gas flow rate and atmosphere were investigated. Experimental results indicated that increasing voltage, treatment time and air flow rate could enhance the formation of •OH. Oxygen atmosphere and a suitable GAC water content were contributed to •OH generation. The results give an insight into plasma chemical processes, and can be helpful to optimize the design and application for the plasma system.

  4. Pleiotropic effects of GacA on Pseudomonas fluorescens Pf0-1 in vitro and in soil.

    PubMed

    Seaton, Sarah C; Silby, Mark W; Levy, Stuart B

    2013-09-01

    Pseudomonas species can exhibit phenotypic variation resulting from gacS or gacA mutation. P. fluorescens Pf0-1 is a gacA mutant and exhibits pleiotropic changes following the introduction of a functional allele. GacA enhances biofilm development while reducing dissemination in soil, suggesting that alternative Gac phenotypes enable Pseudomonas sp. to exploit varied environments. PMID:23811507

  5. The Gac Regulon of Pseudomonas fluorescens SBW25

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transcriptome analysis of Pseudomonas fluorescens SBW25 showed that 702 genes were differentially regulated (FC>4, P<0.0001) in a gacS::Tn5 mutant, with 300 and 402 genes up- and down-regulated, respectively. Similar to the Gac-regulon of four other Pseudomonas species, genes involved in motility, b...

  6. Coupling granular activated carbon adsorption with membrane bioreactor treatment for trace organic contaminant removal: breakthrough behaviour of persistent and hydrophilic compounds.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Kang, Jinguo; Price, William E; Nghiem, Long D

    2013-04-15

    This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes (BV), the same level of breakthrough of the two neutral compounds metronidazole and carbamazepine did not occur until 11,000 BV. Single-solute isotherm parameters did not demonstrate any discernible correlation individually with any of the parameters that may govern adsorption onto GAC, such as log D, number of hydrogen-bond donor/acceptor groups, dipole moment or aromaticity ratio of the compounds. The isotherm data, however, could differentiate the breakthrough behaviour between negatively charged and neutral trace organic contaminants.

  7. A single mutation in the oprF mRNA leader confers strict translational control by the Gac/Rsm system in Pseudomonas fluorescens CHA0.

    PubMed

    Crespo, María Cecilia Alvarez; Valverde, Claudio

    2009-02-01

    The rhizobacterium Pseudomonas fluorescens CHA0 is able to antagonize fungal phytopathogens on a variety of crop plants, mainly due to the production of secondary metabolites that are coordinately upregulated by the global regulatory Gac/Rsm cascade. The two-component system GacS/GacA activates transcription of the three small regulatory RNAs RsmX, RsmY, and RsmZ, which counteract translational repression of target mRNAs by RsmA and RsmE proteins. In a search for novel Gac/Rsm targets based on the minimal sequence on mRNA leaders required for RsmA/RsmE control, the leader region of the major porin OprF emerged as a candidate. Although an isogenic CHA0 oprF mutant showed a reduced ability to attach to cucumber and tomato roots, suggesting a role for OprF in root colonization as a requisite for pathogen antagonism, a translational oprF'-'lacZ fusion was weakly regulated by Gac/Rsm despite its high sequence similarity to the hcnA leader. A single base substitution put the modified oprF 5'-UTR under strict control by Gac/Rsm. The results highlight the subtle sequence requirements of Gac/Rsm targets.

  8. Elimination of micropollutants and transformation products from a wastewater treatment plant effluent through pilot scale ozonation followed by various activated carbon and biological filters.

    PubMed

    Knopp, Gregor; Prasse, Carsten; Ternes, Thomas A; Cornel, Peter

    2016-09-01

    Conventional wastewater treatment plants are ineffective in removing a broad range of micropollutants, resulting in the release of these compounds into the aquatic environment, including natural drinking water resources. Ozonation is a suitable treatment process for micropollutant removal, although, currently, little is known about the formation, behavior, and removal of transformation products (TP) formed during ozonation. We investigated the elimination of 30 selected micropollutants (pharmaceuticals, X-ray contrast media, industrial chemicals, and TP) by biological treatment coupled with ozonation and, subsequently, in parallel with two biological filters (BF) or granular activated carbon (GAC) filters. The selected micropollutants were removed to very different extents during the conventional biological wastewater treatment process. Ozonation (specific ozone consumption: 0.87 ± 0.29 gO3 gDOC(-1), hydraulic retention time: 17 ± 3 min) eliminated a large number of the investigated micropollutants. Although 11 micropollutants could still be detected after ozonation, most of these were eliminated in subsequent GAC filtration at bed volumes (BV) of approximately 25,000 m(3) m(-3). In contrast, no additional removal of micropollutants was achieved in the BF. Ozonation of the analgesic tramadol led to the formation of tramadol-N-oxide that is effectively eliminated by GAC filters, but not by BF. For the antiviral drug acyclovir, the formation of carboxy-acyclovir was observed during activated sludge treatment, with an average concentration of 3.4 ± 1.4 μg L(-1) detected in effluent samples. Subsequent ozonation resulted in the complete elimination of carboxy-acyclovir and led to the formation of N-(4-carbamoyl-2-imino-5-oxo imidazolidin)-formamido-N-methoxyacetetic acid (COFA; average concentration: 2.6 ± 1.0 μg L(-1)). Neither the BF nor the GAC filters were able to remove COFA. These results highlight the importance of considering TP in the

  9. Elimination of micropollutants and transformation products from a wastewater treatment plant effluent through pilot scale ozonation followed by various activated carbon and biological filters.

    PubMed

    Knopp, Gregor; Prasse, Carsten; Ternes, Thomas A; Cornel, Peter

    2016-09-01

    Conventional wastewater treatment plants are ineffective in removing a broad range of micropollutants, resulting in the release of these compounds into the aquatic environment, including natural drinking water resources. Ozonation is a suitable treatment process for micropollutant removal, although, currently, little is known about the formation, behavior, and removal of transformation products (TP) formed during ozonation. We investigated the elimination of 30 selected micropollutants (pharmaceuticals, X-ray contrast media, industrial chemicals, and TP) by biological treatment coupled with ozonation and, subsequently, in parallel with two biological filters (BF) or granular activated carbon (GAC) filters. The selected micropollutants were removed to very different extents during the conventional biological wastewater treatment process. Ozonation (specific ozone consumption: 0.87 ± 0.29 gO3 gDOC(-1), hydraulic retention time: 17 ± 3 min) eliminated a large number of the investigated micropollutants. Although 11 micropollutants could still be detected after ozonation, most of these were eliminated in subsequent GAC filtration at bed volumes (BV) of approximately 25,000 m(3) m(-3). In contrast, no additional removal of micropollutants was achieved in the BF. Ozonation of the analgesic tramadol led to the formation of tramadol-N-oxide that is effectively eliminated by GAC filters, but not by BF. For the antiviral drug acyclovir, the formation of carboxy-acyclovir was observed during activated sludge treatment, with an average concentration of 3.4 ± 1.4 μg L(-1) detected in effluent samples. Subsequent ozonation resulted in the complete elimination of carboxy-acyclovir and led to the formation of N-(4-carbamoyl-2-imino-5-oxo imidazolidin)-formamido-N-methoxyacetetic acid (COFA; average concentration: 2.6 ± 1.0 μg L(-1)). Neither the BF nor the GAC filters were able to remove COFA. These results highlight the importance of considering TP in the

  10. Bioavailability assessments following biochar and activated carbon amendment in DDT-contaminated soil.

    PubMed

    Denyes, Mackenzie J; Rutter, Allison; Zeeb, Barbara A

    2016-02-01

    The effects of 2.8% w/w granulated activated carbon (GAC) and two types of biochar (Burt's and BlueLeaf) on DDT bioavailability in soil (39 μg/g) were investigated using invertebrates (Eisenia fetida), plants (Cucurbita pepo spp. pepo) and a polyoxymethylene (POM) passive sampler method. Biochar significantly reduced DDT accumulation in E. fetida (49%) and showed no detrimental effects to invertebrate health. In contrast, addition of GAC caused significant toxic effects (invertebrate avoidance and decreased weight) and did not significantly reduce the accumulation of DDT into invertebrate tissue. None of the carbon amendments reduced plant uptake of DDT. Bioaccumulation of 4,4'DDT and 4,4'-DDE in plants (C. pepo spp. pepo) and invertebrates (E. fetida) was assessed using bioaccumulation factors (BAFs) and compared to predicted bioavailability using the freely-dissolved porewater obtained from a polyoxymethylene (POM) equilibrium biomimetic method. The bioavailable fraction predicted by the POM samplers correlated well with measured invertebrate uptake (<50% variability), but was different from plant root uptake by 134%. A literature review of C. pepo BAFs across DDT soil contamination levels and the inclusion of field data from a 2.5 μg/g DDT-contaminated site found that these plants exhibit a concentration threshold effect at [DDT](soil) > 10 μg/g. The results of these studies illustrate the importance of including plants in bioavailability studies as the use of carbon materials for in situ contaminant sorption moves from predominantly sediment to soil remediation technologies.

  11. Photocatalytic degradation of carbofuran by TiO2-coated activated carbon: Model for kinetic, electrical energy per order and economic analysis.

    PubMed

    Vishnuganth, M A; Remya, Neelancherry; Kumar, Mathava; Selvaraju, N

    2016-10-01

    The photocatalytic removal of carbofuran (CBF) from aqueous solution in the presence of granular activated carbon supported TiO2 (GAC-TiO2) catalyst was investigated under batch-mode experiments. The presence of GAC enhanced the photocatalytic efficiency of the TiO2 catalyst. Experiments were conducted at different concentrations of CBF to clarify the dependence of apparent rate constant (kapp) in the pseudo first-order kinetics on CBF photodegradation. The general relationship between the adsorption equilibrium constant (K) and reaction rate constant (kr) were explained by using the modified Langmuir-Hinshelwood (L-H) model. From the observed kinetics, it was observed that the surface reaction was the rate limiting step in the GAC-TiO2 catalyzed photodegradation of CBF. The values of K and kr for this pseudo first-order reaction were found to be 0.1942 L  mg(-1) and 1.51 mg L(-1) min(-1), respectively. In addition, the dependence of kapp on the half-life time was determined by calculating the electrical energy per order experimentally (EEO experimental) and also by modeling (EEO model). The batch-mode experimental outcomes revealed the possibility of 100% CBF removal (under optimized conditions and at an initial concentration of 50 mg L(-1) and 100 mg L(-1)) at a contact time of 90 min and 120 min, respectively. Both L-H kinetic model and EEO model fitted well with the batch-mode experimental data and also elucidated successfully the phenomena of photocatalytic degradation in the presence of GAC-TiO2 catalyst.

  12. Adsorption characteristics of activated carbon fibers (ACFs) for toluene: application in respiratory protection.

    PubMed

    Balanay, Jo Anne G; Bartolucci, Alfred A; Lungu, Claudiu T

    2014-01-01

    Granular activated carbon (GAC) is currently the standard adsorbent in respirators against several gases and vapors because of its efficiency, low cost, and available technology. However, a drawback of GAC due to its granular form is its need for containment, adding weight and bulkiness to respirators. This makes respirators uncomfortable to wear, resulting in poor compliance in their use. Activated carbon fibers (ACF) are considered viable alternative adsorbent materials for developing thinner, light-weight, and efficient respirators because of their larger surface area, lighter weight, and fabric form. This study aims to determine the critical bed depth and adsorption capacity of different types of commercially available ACFs for toluene to understand how thin a respirator can be and the service life of the adsorbents, respectively. ACF in cloth (ACFC) and felt (ACFF) forms with three different surface areas per form were tested. Each ACF type was challenged with six concentrations of toluene (50, 100, 200, 300, 400, 500 ppm) at constant air temperature (23°C), relative humidity (50%), and airflow (16 LPM) at different adsorbent weights and bed depths. Breakthrough data were obtained for each adsorbent using gas chromatography with flame ionization detector. The ACFs' surface areas were measured by an automatic physisorption analyzer. The results showed that ACFC has a lower critical bed depth and higher adsorption capacity compared to ACFF with similar surface area for each toluene concentration. Among the ACF types, ACFC2000 (cloth with the highest measured surface area of 1614 ± 5 m(2)/g) has one of the lowest critical bed depths (ranging from 0.11-0.22 cm) and has the highest adsorption capacity (ranging from 595-878 mg/g). Based on these studied adsorption characteristics, it is concluded that ACF has great potential for application in respiratory protection against toluene, particularly the ACFC2000, which is the best candidate for developing thinner and

  13. Activated carbon to the rescue

    SciTech Connect

    Sen, S.

    1996-03-01

    This article describes the response to pipeline spill of ethylene dichloride (EDC) on the property of an oil company. Activated carbon cleanup proceedure was used. During delivery, changeout, transport, storage, thermal reactivation, and return delivery to the site, the carbon never came into direct contact with operating personnel or the atmosphere. More than 10,000 tones of dredge soil and 50 million gallons of surface water were processed during the emergency response.

  14. The Gac/Rsm and cyclic-di-GMP signalling networks coordinately regulate iron uptake in Pseudomonas aeruginosa.

    PubMed

    Frangipani, Emanuela; Visaggio, Daniela; Heeb, Stephan; Kaever, Volkhard; Cámara, Miguel; Visca, Paolo; Imperi, Francesco

    2014-03-01

    Pseudomonas aeruginosa is a versatile bacterial pathogen capable of occupying diverse ecological niches. To cope with iron limitation, P. aeruginosa secretes two siderophores, pyoverdine and pyochelin, whose ability to deliver iron to the cell is crucial for biofilm formation and pathogenicity. In this study, we describe a link between iron uptake and the Gac/Rsm system, a conserved signal transducing pathway of P. aeruginosa that controls the production of extracellular products and virulence factors, as well as the switch from planktonic to biofilm lifestyle. We have observed that pyoverdine and pyochelin production in P. aeruginosa is strongly dependent on the activation state of the Gac/Rsm pathway, which controls siderophore regulatory and biosynthetic genes at the transcriptional level, in a manner that does not involve regulation of ferric uptake regulator (Fur) expression. Gac/Rsm-mediated regulation of iron uptake genes appears to be conserved in different P. aeruginosa strains. Further experiments led to propose that the Gac/Rsm system regulates siderophore production through modulation of the intracellular levels of the second messenger c-di-GMP, indicating that the c-di-GMP and the Gac/Rsm regulatory networks essential for biofilm formation can also coordinately control iron uptake in P. aeruginosa. PMID:23796404

  15. Preparation of polyacrylnitrile (PAN)/ Manganese oxide based activated carbon nanofibers (ACNFs) for adsorption of Cadmium (II) from aqueous solution

    NASA Astrophysics Data System (ADS)

    Abdullah, N.; Yusof, N.; Jaafar, J.; Ismail, AF; Che Othman, F. E.; Hasbullah, H.; Salleh, W. N. W.; Misdan, N.

    2016-06-01

    In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) were prepared via electrospinning process. The electrospun PAN/MnO2-based ACNFs were characterised in term of its morphological structure and specific surface area using SEM and BET analysis respectively. The comparative adsorption study of cadmium (II) ions from aqueous solution between the neat ACNFs, composite ACNFs and commercial granular activated carbon was also conducted. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads with smaller fiber diameter of 437.2 nm as compared to the neat ACNFs which is 575.5 nm. BET analysis elucidated specific surface area of ACNFs/MnO2 to be 67 m2/g. Under adsorption study, it was found out that Cd (II) removal by ACNFs/MnO2 was the highest (97%) followed by neat ACNFs (96%) and GAC (74%).

  16. Metalloradical-catalyzed aliphatic carbon-carbon activation of cyclooctane.

    PubMed

    Chan, Yun Wai; Chan, Kin Shing

    2010-05-26

    The aliphatic carbon-carbon activation of c-octane was achieved via the addition of Rh(ttp)H to give Rh(ttp)(n-octyl) in good yield under mild reaction conditions. The aliphatic carbon-carbon activation was Rh(II)(ttp)-catalyzed and was very sensitive to porphyrin sterics.

  17. Improved granular activated carbon for the stabilization of wastewater pH

    SciTech Connect

    1996-10-01

    Many times the start up of granular activated carbon adsorption systems for the control of organic contaminants in wastewater cm exhibit unacceptable increases in the adscurber effluent pH. Experience shows that the duration of the pH increase ranges from several hours to several days, during which time several hundred bed volumes of water can be discharged with a pH in excess of 9. Laboratory studies have identified the cause of the pH rise as an interaction between the naturally occurring anions and protons ar the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. Capacities of the carbon for the anions range from 2 to 9 mg/g GAC, depending upon the water characteristics, the carbon type, the nature of the anion and its influent concentration. These studies have shown de the anion sorption and resulting pH increase is independent of the raw material used for die activated carbon production, e.g. bituminous or sub-bituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface rather than the water chemistry. The change to the carbon surface is accomplished through a controlled oxidation process. This process provides a more acidic carbon surface with a reduced affinity for the anions in the waste water. As a result, the pH excursions above 9 are eliminated and the initial effluent from the adsorption system can be discharged without further treatment.

  18. Gacs quantum algorithmic entropy in infinite dimensional Hilbert spaces

    SciTech Connect

    Benatti, Fabio; Oskouei, Samad Khabbazi Deh Abad, Ahmad Shafiei

    2014-08-15

    We extend the notion of Gacs quantum algorithmic entropy, originally formulated for finitely many qubits, to infinite dimensional quantum spin chains and investigate the relation of this extension with two quantum dynamical entropies that have been proposed in recent years.

  19. Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon

    EPA Science Inventory

    Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2–persulfate binary mixtur...

  20. Genetic Evidence that Loss of Virulence Associated with gacS or gacA Mutations in Pseudomonas syringae B728a Does Not Result from Effects on Alginate Production

    PubMed Central

    Willis, David K.; Holmstadt, Jeremy J.; Kinscherf, Thomas G.

    2001-01-01

    Mutations in the global regulatory genes gacS and gacA render Pseudomonas syringae pv. syringae strain B728a completely nonpathogenic in foliar infiltration assays on bean plants. It had been previously demonstrated that gac genes regulate alginate production in Pseudomonas species, while other published work indicated that alginate is involved in the pathogenic interaction of P. syringae on bean plants. Together, these results suggested that the effects of gacS and gacA mutations on virulence in B728a might stem directly from a role in regulating alginate. In this report, we confirm a role for gac genes in both algD expression and alginate production in B728a. However, B728a mutants completely devoid of detectable alginate were as virulent as the wild-type strain in our assay. Thus, factors other than, or in addition to, a deficiency of alginate must be involved in the lack of pathogenicity observed with gacS and gacA mutants. PMID:11229941

  1. The effects of mediator and granular activated carbon addition on degradation of trace organic contaminants by an enzymatic membrane reactor.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Price, William E; Leusch, Frederic D L; Roddick, Felicity; Ngo, Hao H; Guo, Wenshan; Magram, Saleh F; Nghiem, Long D

    2014-09-01

    The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 22-55% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (15-45%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 14-25% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent. PMID:24980029

  2. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  3. Activated, coal-based carbon foam

    DOEpatents

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2004-12-21

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  4. Activated, coal-based carbon foam

    SciTech Connect

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2009-06-09

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  5. Aerobic biological activated carbon (BAC) treatment of a phenolic wastewater

    SciTech Connect

    Wei Lin; Weber, A.S. )

    1992-05-01

    Organic removal rates achieved in the aerobic BAC process were comparable to rates typically reported for traditional aerobic fixed-film systems. When operated at organic loading rates lower than 0.03 g COD/g GAC-d and air as the oxygen source, greater than 90% COD removal and 99% phenol removal was achieved. At higher organic loading rates, oxygen limitations resulted in less than optimal performance. Observed oxygen limitations were mitigated by the use of pure oxygen. Long-term stability of operation of the BAC process was excellent with one aerobic BAC column operated under the same conditions in excess of 260 days. During that time, consistent column performance was achieved without the need to provide supplemental carbon or carbon regeneration. System biomass yields ranged from 0.05 to 0.30 g VSS/g COD removed and increased with effluent COD concentration.

  6. Ammonium removal of drinking water at low temperature by activated carbon filter biologically enhanced with heterotrophic nitrifying bacteria.

    PubMed

    Qin, Wen; Li, Wei-Guang; Zhang, Duo-Ying; Huang, Xiao-Fei; Song, Yang

    2016-03-01

    We sought to confirm whether use of Acinetobacter strains Y7 and Y16, both strains of heterotrophic nitrifying bacteria, was practical for removing ammonium (NH4 (+)-N) from drinking water at low temperatures. To test this, ammonium-containing drinking water was treated with strains Y7 and Y16 at 8 and 2 °C. Continuous ammonium treatment was conducted in order to evaluate the performance of three biologically enhanced activated carbon (BEAC) filters in removing ammonium. The three BEAC filters were inoculated with strain Y7, strain Y16, and a mixture of strains Y7 and Y16, respectively. A granular activated carbon (GAC) filter, without inoculation by any strains, was tested in parallel with the BEAC filters as control. The results indicated that NH4 (+)-N removal was significant when a BEAC filter was inoculated with the mixture of strains Y7 and Y16 (BEAC-III filter). Amounts of 0.44 ± 0.05 and 0.25 ± 0.05 mg L(-1) NH4 (+)-N were removed using the BEAC-III filter at 8 and 2 °C, respectively. These values were 2.8-4.0-fold higher than the values of ammonium removal acquired using the GAC filter. The synergistic effect of using strains Y7 and Y16 in concert was the cause of the high-ammonium removal efficiency achieved by using the BEAC-III filter at low temperatures. In addition, a high C/N ratio may promote NH4 (+)-N removal efficiency by improving biomass and microbial activity. This study provides new insight into the use of biofilters to achieve biological removal of ammonium at low temperature. PMID:26527340

  7. Ammonium removal of drinking water at low temperature by activated carbon filter biologically enhanced with heterotrophic nitrifying bacteria.

    PubMed

    Qin, Wen; Li, Wei-Guang; Zhang, Duo-Ying; Huang, Xiao-Fei; Song, Yang

    2016-03-01

    We sought to confirm whether use of Acinetobacter strains Y7 and Y16, both strains of heterotrophic nitrifying bacteria, was practical for removing ammonium (NH4 (+)-N) from drinking water at low temperatures. To test this, ammonium-containing drinking water was treated with strains Y7 and Y16 at 8 and 2 °C. Continuous ammonium treatment was conducted in order to evaluate the performance of three biologically enhanced activated carbon (BEAC) filters in removing ammonium. The three BEAC filters were inoculated with strain Y7, strain Y16, and a mixture of strains Y7 and Y16, respectively. A granular activated carbon (GAC) filter, without inoculation by any strains, was tested in parallel with the BEAC filters as control. The results indicated that NH4 (+)-N removal was significant when a BEAC filter was inoculated with the mixture of strains Y7 and Y16 (BEAC-III filter). Amounts of 0.44 ± 0.05 and 0.25 ± 0.05 mg L(-1) NH4 (+)-N were removed using the BEAC-III filter at 8 and 2 °C, respectively. These values were 2.8-4.0-fold higher than the values of ammonium removal acquired using the GAC filter. The synergistic effect of using strains Y7 and Y16 in concert was the cause of the high-ammonium removal efficiency achieved by using the BEAC-III filter at low temperatures. In addition, a high C/N ratio may promote NH4 (+)-N removal efficiency by improving biomass and microbial activity. This study provides new insight into the use of biofilters to achieve biological removal of ammonium at low temperature.

  8. 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

  9. Thermally activated persulfate oxidation regeneration of NOM- and MTBE- spent granular activated carbon

    EPA Science Inventory

    Chemical oxidation is a developing technology used to regenerate contaminant-spent GAC. Chemical regeneration of GAC represents a viable option to thermal regeneration methods that are energy intensive resulting in significant consumption of fossil fuels and production of greenho...

  10. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  11. EVALUATING CAPACITIES OF GAC PRELOADED WITH NATURAL WATER

    EPA Science Inventory

    Adsorption studies are conducted to determine how preloading a natural groundwater onto GAC affects the adsorption of cis-1,2-dichloroexthene in small-scale and pilot-scale columns. Capacities are determined from batch-isotherm tests, microcolumns, and pilot columns, which are p...

  12. Removal of dissolved organic matter by granular-activated carbon adsorption as a pretreatment to reverse osmosis of membrane bioreactor effluents.

    PubMed

    Gur-Reznik, Shirra; Katz, Ilan; Dosoretz, Carlos G

    2008-03-01

    The adsorption of dissolved organic matter (DOM) on granular-activated carbon (GAC) as a pretreatment to reverse osmosis (RO) desalination of membrane bioreactor (MBR) effluents was studied in lab- and pilot-scale columns. The pattern and efficiency of DOM adsorption and fate of the hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions were characterized, as well as their impact on organic fouling of the RO membranes. Relatively low DOM adsorption capacity and low intensity of adsorption were observed in batch studies. Continuous adsorption experiments performed within a range of hydraulic velocities of 0.9-12m/h depicted permissible values within the mass transfer zone up to 1.6m/h. The breakthrough curves within this range displayed a non-adsorbable fraction of 24+/-6% and a biodegradable fraction of 49+/-12%. Interestingly, the adsorbable fraction remained almost constant ( approximately 30%) in the entire hydraulic range studied. Comparative analysis by HPO interaction chromatography showed a steady removal (63-66%) of the HPO fraction. SUVA index and Fourier Transform Infrared (FTIR) spectra indicated that DOM changes during the adsorption phase were mainly due to elution of the more HPI components. GAC pretreatment in pilot-scale columns resulted in 80-90% DOM removal from MBR effluents, which in turn stabilized membrane permeability and increased permeate quality. FTIR analysis indicated that the residual DOM present in the RO permeate, regardless of the pretreatment, was mainly of HPI character (e.g., low-molecular-weight humics linked to polysaccharides and proteins). The DOM removed by GAC pretreatment is composed mainly of HPO and biodegradable components, which constitutes the fraction primarily causing organic fouling.

  13. SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

    EPA Science Inventory

    The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

  14. Authorized Limit Evaluation of Spent Granular Activated Carbon Used for Vapor-Phase Remediation at the Lawrence Livermore National Laboratory Livermore, California

    SciTech Connect

    Devany, R; Utterback, T

    2007-01-11

    This report provides a technical basis for establishing radiological release limits for granular activated carbon (GAC) containing very low quantities of tritium and radon daughter products generated during environmental remediation activities at Lawrence Livermore National Laboratory (LLNL). This evaluation was conducted according to the Authorized Limit procedures specified in United States Department of Energy (DOE) Order 5400.5, Radiation Protection of the Public and the Environment (DOE, 1993) and related DOE guidance documents. The GAC waste is currently being managed by LLNL as a Resource Conservation and Recovery Act (RCRA) mixed waste. Significant cost savings can be achieved by developing an Authorized Limit under DOE Order 5400.5 since it would allow the waste to be safely disposed as a hazardous waste at a permitted off-site RCRA treatment and disposal facility. LLNL generates GAC waste during vapor-phase soil remediation in the Trailer 5475 area. While trichloroethylene and other volatile organic compounds (VOCs) are the primary targets of the remedial action, a limited amount of tritium and radon daughter products are contained in the GAC at the time of disposal. As defined in DOE Order 5400.5, an Authorized Limit is a level of residual radioactive material that will result in an annual public dose of 100 milliroentgen-equivalent man per year (mrem/year) or less. In 1995, DOE issued additional release requirements for material sent to a landfill that is not an authorized low-level radioactive waste disposal facility. Per guidance, the disposal site will be selected based on a risk/benefit assessment under the As-Low-As-Reasonably-Achievable (ALARA) process while ensuring that individual doses to the public are less than 25 mrem in a year, ground water is protected, the release would not necessitate further remedial action for the disposal site, and the release is coordinated with all appropriate authorities. The 1995 release requirements also state

  15. [Study on influence between activated carbon property and immobilized biological activated carbon purification effect].

    PubMed

    Wang, Guang-zhi; Li, Wei-guang; He, Wen-jie; Han, Hong-da; Ding, Chi; Ma, Xiao-na; Qu, Yan-ming

    2006-10-01

    By means of immobilizing five kinds of activated carbon, we studied the influence between the chief activated carbon property items and immobilized bioactivated carbon (IBAC) purification effect with the correlation analysis. The result shows that the activated carbon property items which the correlation coefficient is up 0.7 include molasses, abrasion number, hardness, tannin, uniform coefficient, mean particle diameter and effective particle diameter; the activated carbon property items which the correlation coefficient is up 0.5 include pH, iodine, butane and tetrachloride. In succession, the partial correlation analysis shows that activated carbon property items mostly influencing on IBAC purification effect include molasses, hardness, abrasion number, uniform coefficient, mean particle diameter and effective particle diameter. The causation of these property items bringing influence on IBAC purification is that the activated carbon holes distribution (representative activated carbon property item is molasses) provides inhabitable location and adjust food for the dominance bacteria; the mechanical resist-crash property of activated carbon (representative activated carbon property items: abrasion number and hardness) have influence on the stability of biofilm; and the particle diameter size and distribution of activated carbon (representative activated carbon property items: uniform coefficient, mean particle diameter and effective particle diameter) can directly affect the force of water in IBAC filter bed, which brings influence on the dominance bacteria immobilizing on activated carbon.

  16. Preparation of activated carbon by chemical activation under vacuum.

    PubMed

    Juan, Yang; Ke-Qiang, Qiu

    2009-05-01

    Activated carbons especially used for gaseous adsorption were prepared from Chinesefir sawdust by zinc chloride activation under vacuum condition. The micropore structure, adsorption properties, and surface morphology of activated carbons obtained under atmosphere and vacuum were investigated. The prepared activated carbons were characterized by SEM, FTIR, and nitrogen adsorption. It was found that the structure of the starting material is kept after activation. The activated carbon prepared under vacuum exhibited higher values of the BET surface area (up to 1079 m2 g(-1)) and total pore volume (up to 0.5665 cm3 g(-1)) than those of the activated carbon obtained under atmosphere. This was attributed to the effect of vacuum condition that reduces oxygen in the system and limits the secondary reaction of the organic vapor. The prepared activated carbon has well-developed microstructure and high microporosity. According to the data obtained, Chinese fir sawdust is a suitable precursor for activated carbon preparation. The obtained activated carbon could be used as a low-cost adsorbent with favorable surface properties. Compared with the traditional chemical activation, vacuum condition demands less energy consumption, simultaneity, and biomass-oil is collected in the procedure more conveniently. FTIR analysis showed that heat treatment would result in the aromatization of the carbon structure. PMID:19534162

  17. Sorption of boron trifluoride by activated carbons

    SciTech Connect

    Polevoi, A.S.; Petrenko, A.E.

    1988-01-10

    The sorption of born trifluoride on AG-3, SKT, SKT-3, SKT-7, SKT-4A, SKT-6A, and SKT-2B carbons was investigated. The sorption isotherms for both vapors and gas were determined volumetrically. The coefficients of two equations described the sorption of BF/sub 3/ in the sorption of BF/sub 3/ on active carbons. Heats of sorption of BF/sub 3/ on the activated carbons are shown and the sorption isotherms and temperature dependences of the equilibrium pressure of BF/sub 3/ for activated carbons were presented. The values of the heats of sorption indicated the weak character of the reaction of BF/sub 3/ with the surface of the carbons. The equations can be used for calculating the phase equilibrium of BF/sub 3/ on carbons in a wider range of temperatures and pressures.

  18. Identification of tertiary butyl alcohol (TBA)-utilizing organisms in BioGAC reactors using 13C-DNA stable isotope probing.

    PubMed

    Aslett, Denise; Haas, Joseph; Hyman, Michael

    2011-09-01

    Biodegradation of the gasoline oxygenates methyl tertiary-butyl ether (MTBE) and ethyl tertiary-butyl ether (ETBE) can cause tertiary butyl alcohol (TBA) to accumulate in gasoline-impacted environments. One remediation option for TBA-contaminated groundwater involves oxygenated granulated activated carbon (GAC) reactors that have been self-inoculated by indigenous TBA-degrading microorganisms in ground water extracted from contaminated aquifers. Identification of these organisms is important for understanding the range of TBA-metabolizing organisms in nature and for determining whether self-inoculation of similar reactors is likely to occur at other sites. In this study (13)C-DNA-stable isotope probing (SIP) was used to identify TBA-utilizing organisms in samples of self-inoculated BioGAC reactors operated at sites in New York and California. Based on 16S rRNA nucleotide sequences, all TBA-utilizing organisms identified were members of the Burkholderiales order of the β-proteobacteria. Organisms similar to Cupriavidus and Methylibium were observed in both reactor samples while organisms similar to Polaromonas and Rhodoferax were unique to the reactor sample from New York. Organisms similar to Hydrogenophaga and Paucibacter strains were only detected in the reactor sample from California. We also analyzed our samples for the presence of several genes previously implicated in TBA oxidation by pure cultures of bacteria. Genes Mpe_B0532, B0541, B0555, and B0561 were all detected in (13)C-metagenomic DNA from both reactors and deduced amino acid sequences suggested these genes all encode highly conserved enzymes. One gene (Mpe_B0555) encodes a putative phthalate dioxygenase-like enzyme that may be particularly appropriate for determining the potential for TBA oxidation in contaminated environmental samples.

  19. Carotenoids concentration of Gac (Momordica cochinchinensis Spreng.) fruit oil using cross-flow filtration technology.

    PubMed

    Mai, Huỳnh Cang; Truong, Vinh; Debaste, Frédéric

    2014-11-01

    Gac (Momordica cochinchinensis Spreng.) fruit, a traditional fruit in Vietnam and other countries of eastern Asia, contains an oil rich in carotenoids, especially lycopene and β-carotene. Carotenoids in gac fruit oil were concentrated using cross-flow filtration. In total recycle mode, effect of membrane pore size, temperature, and transmembrane pressure (TMP) on permeate flux and on retention coefficients has been exploited. Resistance of membrane, polarization concentration, and fouling were also analyzed. Optimum conditions for a high permeate flux and a good carotenoids retention are 5 nm, 2 bars, and 40 °C of membrane pore size, TMP, and temperature, respectively. In batch mode, retentate was analyzed through index of acid, phospholipids, total carotenoids content (TCC), total antioxidant activity, total soluble solids, total solid content, color measurement, and viscosity. TCC in retentate is higher 8.6 times than that in feeding oil. Lipophilic antioxidant activities increase 6.8 times, while hydrophilic antioxidant activities reduce 40%. The major part of total resistance is due to polarization (55%) while fouling and intrinsic membrane contribute about 30% and 24%, respectively. PMID:25367308

  20. Carotenoids concentration of Gac (Momordica cochinchinensis Spreng.) fruit oil using cross-flow filtration technology.

    PubMed

    Mai, Huỳnh Cang; Truong, Vinh; Debaste, Frédéric

    2014-11-01

    Gac (Momordica cochinchinensis Spreng.) fruit, a traditional fruit in Vietnam and other countries of eastern Asia, contains an oil rich in carotenoids, especially lycopene and β-carotene. Carotenoids in gac fruit oil were concentrated using cross-flow filtration. In total recycle mode, effect of membrane pore size, temperature, and transmembrane pressure (TMP) on permeate flux and on retention coefficients has been exploited. Resistance of membrane, polarization concentration, and fouling were also analyzed. Optimum conditions for a high permeate flux and a good carotenoids retention are 5 nm, 2 bars, and 40 °C of membrane pore size, TMP, and temperature, respectively. In batch mode, retentate was analyzed through index of acid, phospholipids, total carotenoids content (TCC), total antioxidant activity, total soluble solids, total solid content, color measurement, and viscosity. TCC in retentate is higher 8.6 times than that in feeding oil. Lipophilic antioxidant activities increase 6.8 times, while hydrophilic antioxidant activities reduce 40%. The major part of total resistance is due to polarization (55%) while fouling and intrinsic membrane contribute about 30% and 24%, respectively.

  1. Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon

    SciTech Connect

    Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd.; Rinaldi, A.; Su, D. S.; Schlogl, R.

    2009-06-01

    Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

  2. Making Activated Carbon by Wet Pressurized Pyrolysis

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Pisharody, Suresh; Wignarajah, K.; Moran, Mark

    2006-01-01

    A wet pressurized pyrolysis (wet carbonization) process has been invented as a means of producing activated carbon from a wide variety of inedible biomass consisting principally of plant wastes. The principal intended use of this activated carbon is room-temperature adsorption of pollutant gases from cooled incinerator exhaust streams. Activated carbon is highly porous and has a large surface area. The surface area depends strongly on the raw material and the production process. Coconut shells and bituminous coal are the primary raw materials that, until now, were converted into activated carbon of commercially acceptable quality by use of traditional production processes that involve activation by use of steam or carbon dioxide. In the wet pressurized pyrolysis process, the plant material is subjected to high pressure and temperature in an aqueous medium in the absence of oxygen for a specified amount of time to break carbon-oxygen bonds in the organic material and modify the structure of the material to obtain large surface area. Plant materials that have been used in demonstrations of the process include inedible parts of wheat, rice, potato, soybean, and tomato plants. The raw plant material is ground and mixed with a specified proportion of water. The mixture is placed in a stirred autoclave, wherein it is pyrolized at a temperature between 450 and 590 F (approximately between 230 and 310 C) and a pressure between 1 and 1.4 kpsi (approximately between 7 and 10 MPa) for a time between 5 minutes and 1 hour. The solid fraction remaining after wet carbonization is dried, then activated at a temperature of 500 F (260 C) in nitrogen gas. The activated carbon thus produced is comparable to commercial activated carbon. It can be used to adsorb oxides of sulfur, oxides of nitrogen, and trace amounts of hydrocarbons, any or all of which can be present in flue gas. Alternatively, the dried solid fraction can be used, even without the activation treatment, to absorb

  3. Characterization of full-scale carbon contactors for siloxane removal from biogas using online Fourier transform infrared spectroscopy.

    PubMed

    Hepburn, C A; Martin, B D; Simms, N; McAdam, E J

    2015-01-01

    In this study, online Fourier transform infrared (FTIR) spectroscopy has been used to generate the first comprehensive characterization of full-scale carbon contactors for siloxane removal from biogas. Using FTIR, two clear operational regions within the exhaustion cycle were evidenced: an initial period of pseudo-steady state where the outlet siloxane concentration was consistently below the proposed siloxane limits; and a second period characterized by a progressive rise in outlet siloxane concentration during and after breakthrough. Due to the sharp breakthrough front identified, existing detection methods (which comprise field sampling coupled with laboratory-based chromatographic determination) are insufficiently responsive to define breakthrough, thus carbon contactors currently remain in service while providing limited protection to the combined heat and power engine. Integration of the exhaustion cycle to breakthrough identified average specific media capacities of 8.5-21.5 gsiloxane kg(-1)GAC, which are lower than that has been reported for vapour phase granular activated carbon (GAC). Further speciation of the biogas phase identified co-separation of organic compounds (alkanes and aromatics), which will inevitably reduce siloxane capacity. However, comparison of the five full-scale contactors identified that greater media capacity was accessible through operating contactors at velocities sufficient to diminish axial dispersion effects. In addition to enabling significant insight into gas phase GAC contactors, the use of FTIR for online control of GAC for siloxane removal is also presented.

  4. 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.

  5. 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

  6. Electrosorption/Electrodesorption of Arsenic on a Granular Activated Carbon in the Presence of Other Heavy Metals.

    PubMed

    Bain, Euan J; Calo, Joseph M; Spitz-Steinberg, Ruben; Kirchner, Johannes; Axén, Jenny

    2010-06-17

    The adsorption, electrosorption, and electrodesorption of aqueous, inorganic arsenic on the granular activated carbon (GAC), DARCO((R)) 12x20 GAC was investigated in solutions containing arsenic as the only contaminant, as well as with chromium, nickel and iron. Darco 1220 was selected for these investigations primarily because it is relatively ineffective as a normal (unassisted) arsenic adsorbent in the chosen electrolytes at the low loadings used. It is shown that the application of anodic potentials in the 1.0 - 1.5V range, however, result in enhanced uptake, most probably due to charging of the electrochemical double-layer at the electrode surface. 100% regeneration of electrosorbed arsenic was achieved via electrodesorption at a cathodic potential of 1.50V. The presence of ad-metal ions was observed to have a significant and complex effect on arsenic adsorption, electrosorption, and electrodesorption. In particular, the Cr:As ratio was shown to have complex effects, decreasing adsorption uptake when present as 3:2, but enhancing adsorption when present as 5:1. Nickel was found to have less of an effect than chromium except at the highest anodic potential used of 1.50V, where it exhibited better performance than chromium. The presence of iron significantly enhanced uptake. With a 1.50V anodic potential, the bulk arsenic concentration was reduced to less than detectable limits, well below the USEPA MCL for drinking water. Regeneration efficiency by electrodesorption for the As-Fe system was greater than about 90%.

  7. Effects of activated carbon amended sediment on biological responses in Chironomus riparius multi-generation testing.

    PubMed

    Nybom, Inna; Abel, Sebastian; Mäenpää, Kimmo; Akkanen, Jarkko

    2016-11-15

    The biological effects of activated carbon (AC) amendments in sediments were studied with the midge Chironomus riparius. The effects on larvae growth were studied using three different AC particles sizes (PAC: 90% <63μm, MAC: ø 63-200μm and GAC: ø 420-1700μm). The long- term effects of MAC were studied in an emergence experiment over two generations (P, F1), together with larvae growth experiment over three generations (P, F1, F2). Retarded growth and development of the larvae were observed in the two smallest particle sizes (PAC and MAC), as well as morphological changes in the gut wall microvilli layer studied from transmission electron micrographs. In addition, at high AC treatments the larvae reaching fourth instar stage were of a smaller size compared to the controls. With PAC treatment AC amendment dosages higher than 1% of sediment dry weight induced mortality. In the emergence experiment there was an indication of a delay in F1 generation emergence. Male dry weight (dw) in P generation was significantly reduced in the 2.5% MAC treatment. The effects of AC amendments were more obvious in the C. riparius larvae compared to the effects seen in emerging adults exposed to AC-amended sediment during the larval stage. PMID:27450330

  8. Measuring and Modeling Organochlorine Pesticide Response to Activated Carbon Amendment in Tidal Sediment Mesocosms.

    PubMed

    Thompson, Jay M; Hsieh, Ching-Hong; Hoelen, Thomas P; Weston, Donald P; Luthy, Richard G

    2016-05-01

    Activated carbon (AC) sediment amendment for hydrophobic organic contaminants (HOCs) is attracting increasing regulatory and industrial interest. However, mechanistic and well-vetted models are needed. Here, we conduct an 18 month field mesocosm trial at a site containing dichlorodiphenyltrichloroethane (DDT) and chlordane. Different AC applications were applied and, for the first time, a recently published mass transfer model was field tested under varying experimental conditions. AC treatment was effective in reducing DDT and chlordane concentration in polyethylene (PE) samplers, and contaminant extractability by Arenicola brasiliensis digestive fluids. A substantial AC particle size effect was observed. For example, chlordane concentration in PE was reduced by 93% 6 months post-treatment in the powdered AC (PAC) mesocosm, compared with 71% in the granular AC (GAC) mesocosm. Extractability of sediment-associated DDT and chlordane by A. brasiliensis digestive fluids was reduced by at least a factor of 10 in all AC treatments. The model reproduced the relative effects of varying experimental conditions (particle size, dose, mixing time) on concentrations in polyethylene passive samplers well, in most cases within 25% of experimental observations. Although uncertainties such as the effect of long-term AC fouling by organic matter remain, the study findings support the use of the model to assess long-term implications of AC amendment. PMID:27040592

  9. Photocatalytic oxidation and removal of arsenite by titanium dioxide supported on granular activated carbon.

    PubMed

    Yao, Shu Hua; Jia, Yong Feng; Zhao, Shan Lin

    2012-01-01

    Arsenic contamination in drinking water is a worldwide concern. Photocatalysis can rapidly oxidize arsenite, i.e. As(III), to less labile arsenate, i.e. As(V), which then can be removed by adsorption on to various adsorbents. This study investigated the photocatalytic oxidation of arsenite in aqueous solution by granular activated carbon supporting a titanium dioxide photocatalyst (GAC-TiO2). The effects of photocatalyst dosage, solution pH values, initial concentration of As(III) and co-anions (SO4(2-), PO4(3-), SiO3(2-) and Cl-) on the oxidation of As(III) were studied. The photocatalytic oxidation of As(III) took place in minutes and followed first-order kinetics. The presence of phosphate and silicate significantly decreased As(III) oxidation, while the effect of sulphate, chloride was insignificant. The oxidation efficiency of As(III) was observed to increase with increasing pH. The results suggest that the supported photocatalyst developed in this study is an ideal candidate for pre-oxidation treatment of arsenic-contaminated water.

  10. Effects of activated carbon amended sediment on biological responses in Chironomus riparius multi-generation testing.

    PubMed

    Nybom, Inna; Abel, Sebastian; Mäenpää, Kimmo; Akkanen, Jarkko

    2016-11-15

    The biological effects of activated carbon (AC) amendments in sediments were studied with the midge Chironomus riparius. The effects on larvae growth were studied using three different AC particles sizes (PAC: 90% <63μm, MAC: ø 63-200μm and GAC: ø 420-1700μm). The long- term effects of MAC were studied in an emergence experiment over two generations (P, F1), together with larvae growth experiment over three generations (P, F1, F2). Retarded growth and development of the larvae were observed in the two smallest particle sizes (PAC and MAC), as well as morphological changes in the gut wall microvilli layer studied from transmission electron micrographs. In addition, at high AC treatments the larvae reaching fourth instar stage were of a smaller size compared to the controls. With PAC treatment AC amendment dosages higher than 1% of sediment dry weight induced mortality. In the emergence experiment there was an indication of a delay in F1 generation emergence. Male dry weight (dw) in P generation was significantly reduced in the 2.5% MAC treatment. The effects of AC amendments were more obvious in the C. riparius larvae compared to the effects seen in emerging adults exposed to AC-amended sediment during the larval stage.

  11. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  12. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  13. ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT

    SciTech Connect

    Edwin S. Olson; Daniel J. Stepan

    2000-07-01

    High concentrations of humate in surface water result in the formation of excess amounts of chlorinated byproducts during disinfection treatment. These precursors can be removed in water treatment prior to disinfection using powdered activated carbon. In the interest of developing a more cost-effective method for removal of humates in surface water, a comparison of the activities of carbons prepared from North Dakota lignites with those of commercial carbons was conducted. Previous studies indicated that a commercial carbon prepared from Texas lignite (Darco HDB) was superior to those prepared from bituminous coals for water treatment. That the high alkali content of North Dakota lignites would result in favorable adsorptive properties for the very large humate molecules was hypothesized, owing to the formation of larger pores during activation. Since no standard humate test has been previously developed, initial adsorption testing was performed using smaller dye molecules with various types of ionic character. With the cationic dye, methylene blue, a carbon prepared from a high-sodium lignite (HSKRC) adsorbed more dye than the Darco HDB. The carbon from the low-sodium lignite was much inferior. With another cationic dye, malachite green, the Darco HDB was slightly better. With anionic dyes, methyl red and azocarmine-B, the results for the HSKRC and Darco HDB were comparable. A humate test was developed using Aldrich humic acid. The HSKRC and the Darco HDB gave equally high adsorption capacities for the humate (138 mg/g), consistent with the similarities observed in earlier tests. A carbon prepared from a high-sodium lignite from a different mine showed an outstanding improvement (201 mg/g). The carbons prepared from the low-sodium lignites from both mines showed poor adsorption capacities for humate. Adsorption isotherms were performed for the set of activated carbons in the humate system. These exhibited a complex behavior interpreted as resulting from two types

  14. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G.

    1996-12-31

    This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

  15. Combined removal of BTEX in air stream by using mixture of sugar cane bagasse, compost and GAC as biofilter media.

    PubMed

    Mathur, Anil K; Majumder, C B; Chatterjee, Shamba

    2007-09-01

    Biofiltration of air stream containing mixture of benzene, toluene, ethyl benzene and o-xylene (BTEX) has been studied in a lab-scale biofilter packed with a mixture of compost, sugar cane bagasse and granulated activated carbon (GAC) in the ratio 55:30:15 by weight. Microbial acclimation was achieved in 30 days by exposing the system to average BTEX inlet concentration of 0.4194 gm(-3) at an empty bed residence time (EBRT) of 2.3 min. Biofilter achieved maximum removal efficiency more than 99% of all four compounds for throughout its operation at an EBRT of 2.3 min for an inlet concentration of 0.681 gm(-3), which is quite significance than the values reported in the literature. The results indicate that when the influent BTEX loadings were less than 68 gm(-3)h(-1) in the biofilter, nearly 100% removal could be achieved. A maximum elimination capacity (EC) of 83.65 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 126.5 gm(-3)h(-1) in phase IV. Elimination capacities of BTEX increased with the increase in influent VOC loading, but an opposite trend was observed for the removal efficiency. The production of CO(2) in each phase (gm(-3)h(-1)) was also observed at steady state (i.e. at maximum removal efficiency). Moreover, the high concentrations of nitrogen in the nutrient solution may adversely affect the microbial activity possibly due to the presence of high salt concentrations. Furthermore, an attempt was also made to isolate the most profusely grown BTEX-degrading strain. A Gram-positive strain had a high BTEX-degrading activity and was identified as Bacillus sphaericus by taxonomical analysis, biochemical tests and 16S rDNA gene analysis methods.

  16. Organic solvent regeneration of granular activated carbon

    NASA Astrophysics Data System (ADS)

    Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

    1982-09-01

    The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

  17. Adsorption of methyl mercaptan on activated carbons.

    PubMed

    Bashkova, Svetlana; Bagreev, Andrey; Bandosz, Teresa J

    2002-06-15

    Activated carbons of different origins were studied as methyl mercaptan adsorbents in wet, dry, and oxidizing conditions. The materials were characterized using adsorption of nitrogen, Boehm titration, and thermal analysis. Investigation was focused on the feasibility of the removal of methyl mercaptan on activated carbons and on the role of surface chemistry and porosity in the adsorption/oxidation processes. The results showed relatively high capacities of carbons for removal of CH3SH. The amount adsorbed depends on the surface features. Methyl mercaptan, in general, is oxidized to disulfides, which, depending on the chemistry of the carbon surface, can be converted to sulfonic acid due to the presence of water and active radicals.

  18. Antimicrobial Activity of Carbon-Based Nanoparticles

    PubMed Central

    Maleki Dizaj, Solmaz; Mennati, Afsaneh; Jafari, Samira; Khezri, Khadejeh; Adibkia, Khosro

    2015-01-01

    Due to the vast and inappropriate use of the antibiotics, microorganisms have begun to develop resistance to the commonly used antimicrobial agents. So therefore, development of the new and effective antimicrobial agents seems to be necessary. According to some recent reports, carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs) (especially single-walled carbon nanotubes (SWCNTs)) and graphene oxide (GO) nanoparticles show potent antimicrobial properties. In present review, we have briefly summarized the antimicrobial activity of carbon-based nanoparticles together with their mechanism of action. Reviewed literature show that the size of carbon nanoparticles plays an important role in the inactivation of the microorganisms. As major mechanism, direct contact of microorganisms with carbon nanostructures seriously affects their cellular membrane integrity, metabolic processes and morphology. The antimicrobial activity of carbon-based nanostructures may interestingly be investigated in the near future owing to their high surface/volume ratio, large inner volume and other unique chemical and physical properties. In addition, application of functionalized carbon nanomaterials as carriers for the ordinary antibiotics possibly will decrease the associated resistance, enhance their bioavailability and provide their targeted delivery. PMID:25789215

  19. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons.

  20. Activated coconut shell charcoal carbon using chemical-physical activation

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Umiatin, Nasbey, Hadi; Bintoro, Ridho Akbar; Wulandari, Futri; Erlina

    2016-02-01

    The use of activated carbon from natural material such as coconut shell charcoal as metal absorbance of the wastewater is a new trend. The activation of coconut shell charcoal carbon by using chemical-physical activation has been investigated. Coconut shell was pyrolized in kiln at temperature about 75 - 150 °C for about 6 hours in producing charcoal. The charcoal as the sample was shieved into milimeter sized granule particle and chemically activated by immersing in various concentration of HCl, H3PO4, KOH and NaOH solutions. The samples then was physically activated using horizontal furnace at 400°C for 1 hours in argon gas environment with flow rate of 200 kg/m3. The surface morphology and carbon content of activated carbon were characterized by using SEM/EDS. The result shows that the pores of activated carbon are openned wider as the chemical activator concentration is increased due to an excessive chemical attack. However, the pores tend to be closed as further increasing in chemical activator concentration due to carbon collapsing.

  1. Evaluation of an integrated sponge--granular activated carbon fluidized bed bioreactor for treating primary treated sewage effluent.

    PubMed

    Xing, W; Ngo, H H; Guo, W S; Listowski, A; Cullum, P

    2011-05-01

    An integrated fluidized bed bioreactor (iFBBR) was designed to incorporate an aerobic sponge FBBR (ASB-FBBR) into an anoxic granular activated carbon FBBR (GAC-FBBR). This iFBBR was operated with and without adding a new starch based flocculant (NSBF) to treat synthetic primary treated sewage effluent (PTSE). The NSBF contains starch based cationic flocculants and trace nutrients. The results indicate that the iFBBR with NSBF addition could remove more than 93% dissolved organic carbon (DOC), 61% total nitrogen (T-N) and 60% total phosphorus (T-P) at just a very short hydraulic retention time of 50 min. The optimum frequency of adding NSBF to the iFFBR is four times per day. As a pretreatment to microfiltration, the iFFBR could increase 5L/m(2)h of critical flux thus reducing the membrane fouling. In addition, better microbial activity was also observed with high DO consumption (>66%) and specific oxygen uptake rate (>35 mg O(2)/g VSS h).

  2. Bioturbation and dissolved organic matter enhance contaminant fluxes from sediment treated with powdered and granular activated carbon.

    PubMed

    Kupryianchyk, D; Noori, A; Rakowska, M I; Grotenhuis, J T C; Koelmans, A A

    2013-05-21

    Sediment amendment with activated carbon (AC) is a promising technique for in situ sediment remediation. To date it is not clear whether this technique sufficiently reduces sediment-to-water fluxes of sediment-bound hydrophobic organic chemicals (HOCs) in the presence of bioturbators. Here, we report polychlorobiphenyl (PCB) pore water concentrations, fluxes, mass transfer coefficients, and survival data of two benthic species, for four treatments: no AC addition (control), powdered AC addition, granular AC addition and addition and subsequent removal of GAC (sediment stripping). AC addition decreased mass fluxes but increased apparent mass transfer coefficients because of dissolved organic carbon (DOC) facilitated transport across the benthic boundary layer (BBL). In turn, DOC concentrations depended on bioturbator activity which was high for the PAC tolerant species Asellus aquaticus and low for AC sensitive species Lumbriculus variegatus. A dual BBL resistance model combining AC effects on gradients, DOC facilitated transport and biodiffusion was evaluated against the data and showed how the type of resistance differs with treatment and chemical hydrophobicity. Data and simulations illustrate the complex interplay between AC and contaminant toxicity to benthic organisms and how differences in species tolerance affect mass fluxes from sediment to the water column. PMID:23590290

  3. The effect of water temperature on the adsorption equilibrium of dissolved organic matter and atrazine on granular activated carbon

    SciTech Connect

    Bernd Schreiber; Viktor Schmalz; Thomas Brinkmann; Eckhard Worch

    2007-09-15

    The influence of water temperature on the adsorption of natural dissolved organic matter (DOM) on activated carbon has not been investigated intensively yet. In this study, batch experiments with granular activated carbon (GAC) F300, from bituminous coal, have been carried out at three temperatures (5, 20, 35{sup o} C) using a humic acid model water and different types of surface water (lake, river, canal). Furthermore, the adsorption of an anthropogenic contaminant, atrazine, was quantified in the absence and presence of DOM. The results indicate a significant influence of water temperature on the adsorption equilibrium of DOM and atrazine. Contrary to expectations, DOM and atrazine adsorption in surface water tends to be increased with increasing water temperature, whereas the extent of this effect is dependent on the type and concentration of DOM. Furthermore, the temperature effect on atrazine adsorption is controlled by competition of DOM and atrazine on adsorption sites. Some assumptions are proposed and discussed for explaining the temperature effects observed in the batch studies. 39 refs., 4 figs., 2 tabs.

  4. Magnetically driven anisotropic structural changes in the atomic laminate M n2GaC

    NASA Astrophysics Data System (ADS)

    Dahlqvist, M.; Ingason, A. S.; Alling, B.; Magnus, F.; Thore, A.; Petruhins, A.; Mockute, A.; Arnalds, U. B.; Sahlberg, M.; Hjörvarsson, B.; Abrikosov, I. A.; Rosen, J.

    2016-01-01

    Inherently layered magnetic materials, such as magnetic Mn +1A Xn (MAX) phases, offer an intriguing perspective for use in spintronics applications and as ideal model systems for fundamental studies of complex magnetic phenomena. The MAX phase composition Mn+1A Xn consists of Mn +1Xn blocks separated by atomically thin A -layers where M is a transition metal, A an A-group element, X refers to carbon and/or nitrogen, and n is typically 1, 2, or 3. Here, we show that the recently discovered magnetic M n2GaC MAX phase displays structural changes linked to the magnetic anisotropy, and a rich magnetic phase diagram which can be manipulated through temperature and magnetic field. Using first-principles calculations and Monte Carlo simulations, an essentially one-dimensional (1D) interlayer plethora of two-dimensioanl (2D) Mn-C-Mn trilayers with robust intralayer ferromagnetic spin coupling was revealed. The complex transitions between them were observed to induce magnetically driven anisotropic structural changes. The magnetic behavior as well as structural changes dependent on the temperature and applied magnetic field are explained by the large number of low energy, i.e., close to degenerate, collinear and noncollinear spin configurations that become accessible to the system with a change in volume. These results indicate that the magnetic state can be directly controlled by an applied pressure or through the introduction of stress and show promise for the use of M n2GaC MAX phases in future magnetoelectric and magnetocaloric applications.

  5. Effects of full-stream carbon filtration on the development of head and lateral line erosion syndrome (HLLES) in ocean surgeon.

    PubMed

    Stamper, M Andrew; Kittell, Michele M; Patel, Erin E; Corwin, Allison L

    2011-09-01

    Head and lateral line erosion syndrome (HLLES) is a common but very poorly understood disease of marine aquarium fish. One suspected etiology is the use of granulated activated carbon (GAC) to filter the water. Seventy-two ocean surgeons Acanthurus bahianus were distributed among three carbon-negative control systems and three GAC-treated systems such that each tank contained approximately the same total body mass. Each replicate system was made up of two 250-L circular tanks with a common filtration system (6 fish per tank, 12 fish per replicate system). The GAC-treated tanks were exposed to full-stream, extruded coconut shell activated carbon, which produced a mean total organic carbon content of 0.4 mg/L. The results of this study indicate that extruded coconut shell activated carbon filtering at full-stream rates can cause HLLES-type lesions in ocean surgeons. The HLLES developed exponentially over 15 d, beginning in the chin region. This was followed by pitting in the cheek region, which expanded until erosions coalesced. Once the carbon was discontinued, the processes reversed in a mean time of 49 d. As the lesions healed, they reverted from the coalesced to the pitted stage and then darkened before returning to normal. PMID:22216709

  6. Effects of full-stream carbon filtration on the development of head and lateral line erosion syndrome (HLLES) in ocean surgeon.

    PubMed

    Stamper, M Andrew; Kittell, Michele M; Patel, Erin E; Corwin, Allison L

    2011-09-01

    Head and lateral line erosion syndrome (HLLES) is a common but very poorly understood disease of marine aquarium fish. One suspected etiology is the use of granulated activated carbon (GAC) to filter the water. Seventy-two ocean surgeons Acanthurus bahianus were distributed among three carbon-negative control systems and three GAC-treated systems such that each tank contained approximately the same total body mass. Each replicate system was made up of two 250-L circular tanks with a common filtration system (6 fish per tank, 12 fish per replicate system). The GAC-treated tanks were exposed to full-stream, extruded coconut shell activated carbon, which produced a mean total organic carbon content of 0.4 mg/L. The results of this study indicate that extruded coconut shell activated carbon filtering at full-stream rates can cause HLLES-type lesions in ocean surgeons. The HLLES developed exponentially over 15 d, beginning in the chin region. This was followed by pitting in the cheek region, which expanded until erosions coalesced. Once the carbon was discontinued, the processes reversed in a mean time of 49 d. As the lesions healed, they reverted from the coalesced to the pitted stage and then darkened before returning to normal.

  7. [Removal of phthalate esters from drinking water using ozone-GAC process].

    PubMed

    Liu, Jun; Wang, Ke; Jia, Ruibao; Wang, Zhansheng

    2003-07-01

    This study investigated the feasibility of using ozone-GAC process to remove phthalate esters from drinking water through a batch-scale study and adsorption isotherms. Dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP) were selected as the representative of phthalate esters. Results indicated that ozonation remove more than 40% DMP, DEP and DBP, GAC absorbed all the DMP, DEP and DBP that had not been oxidized by ozone at the condition of the Empty Bed Contact Time (EBCT) from 4 minutes to 12 minutes. The isotherms for GAC were successful correlated by Freundlich equation, and the date was used to estimate GAC service time. The results indicated that ozone-GAC process is a feasible way to remove DMP, DEP and DBP from drinking water. PMID:14551961

  8. A novel activated carbon for supercapacitors

    SciTech Connect

    Shen, Haijie; Liu, Enhui; Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer A novel activated carbon was prepared from phenol-melamine-formaldehyde resin. Black-Right-Pointing-Pointer The carbon has large surface area with microporous, and high heteroatom content. Black-Right-Pointing-Pointer Heteroatom-containing functional groups can improve the pseudo-capacitance. Black-Right-Pointing-Pointer Physical and chemical properties lead to the good electrochemical properties. -- Abstract: A novel activated carbon has been prepared by simple carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The morphology, thermal stability, surface area, elemental composition and surface chemical composition of samples have been investigated by scanning electron microscope, thermogravimetry and differential thermal analysis, Brunauer-Emmett-Teller measurement, elemental analysis and X-ray photoelectron spectroscopy, respectively. Electrochemical properties have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol L{sup -1} potassium hydroxide. The activated carbon shows good capacitive behavior and the specific capacitance is up to 210 F g{sup -1}, which indicates that it may be a promising candidate for supercapacitors.

  9. Comparison of granular activated carbon and macroreticular synthetic adsorbents for groundwater remediation

    SciTech Connect

    Musterman, J.L.; Boero, V.J.; Plantz, D.A.

    1995-12-31

    An evaluation of Calgon F-400 and Ambersorb 563 and 572 and XAD-4 resins for removal of VOCs from an activated sludge treated groundwater was performed using continuous flow reactors. Breakthrough and EBCT-ST curves were developed and the capacities of the adsorbents were determined. Comparison of the performance of the adsorbents indicated that: (1) Ambersorb 563 resin provided greater VOC adsorption capacity and run-time to breakthrough than Ambersorb 572 and XAD-4 resins or the F-400 GAC. (2) Ambersorb 563 resin could also be operated at three times the surface loading rate of the GAC system resulting in smaller equipment size. (3) The Ambersorb 563 resin showed negligible TOC removal despite a high specificity for the target organic analytes. A cost analysis indicated that the installed cost for a 6.31 L/s Ambersorb 563 resin system was 2.8 times the cost of a F-400 GAC system. The annual operating cost however, was four times lower and the total present worth was $549,000 less.

  10. Inhibition of seed germination and induction of systemic disease resistance by Pseudomonas chlororaphis O6 requires phenazine production regulated by the global regulator, gacS.

    PubMed

    Kang, Beom Ryong; Han, Song Hee; Zdor, Rob E; Anderson, Anne J; Spencer, Matt; Yang, Kwang Yeol; Kim, Yong Hwan; Lee, Myung Chul; Cho, Baik Ho; Kim, Young Cheol

    2007-04-01

    Seed coating by a phenazine-producing bacterium, Pseudomonas chlororaphis O6, induced dose-dependent inhibition of germination in wheat and barley seeds, but did not inhibit germination of rice or cucumber seeds. In wheat seedlings grown from inoculated seeds, phenazine production levels near the seed were higher than in the roots. Deletion of the gacS gene reduced transcription from the genes required for phenazine synthesis, the regulatory phzI gene and the biosynthetic phzA gene. The inhibition of seed germination and the induction of systemic disease resistance against a bacterial soft-rot pathogen, Erwinia carotovora subsp. carotovora, were impaired in the gacS and phzA mutants of P chlororaphis O6. Culture filtrates of the gacS and phzA mutants of P chlororaphis 06 did not inhibit seed germination of wheat, whereas that of the wild-type was inhibitory. Our results showed that the production of phenazines by P chlororaphis O6 was correlated with reduced germination of barley and wheat seeds, and the level of systemic resistance in tobacco against E. carotovora.

  11. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

    Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

    2012-02-01

    The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

  12. GacA is essential for Group A S treptococcus and defines a new class of monomeric dTDP‐4‐dehydrorhamnose reductases (RmlD)

    PubMed Central

    van der Beek, Samantha L.; Le Breton, Yoann; Ferenbach, Andrew T.; Chapman, Robert N.; van Aalten, Daan M. F.; Navratilova, Iva; Boons, Geert‐Jan; McIver, Kevin S.

    2015-01-01

    Summary The sugar nucleotide dTDP‐L‐rhamnose is critical for the biosynthesis of the Group A Carbohydrate, the molecular signature and virulence determinant of the human pathogen Group A S treptococcus (GAS). The final step of the four‐step dTDP‐L‐rhamnose biosynthesis pathway is catalyzed by dTDP‐4‐dehydrorhamnose reductases (RmlD). RmlD from the Gram‐negative bacterium S almonella is the only structurally characterized family member and requires metal‐dependent homo‐dimerization for enzymatic activity. Using a biochemical and structural biology approach, we demonstrate that the only RmlD homologue from GAS, previously renamed GacA, functions in a novel monomeric manner. Sequence analysis of 213 Gram‐negative and Gram‐positive RmlD homologues predicts that enzymes from all Gram‐positive species lack a dimerization motif and function as monomers. The enzymatic function of GacA was confirmed through heterologous expression of gac A in a S. mutans rml D knockout, which restored attenuated growth and aberrant cell division. Finally, analysis of a saturated mutant GAS library using Tn‐sequencing and generation of a conditional‐expression mutant identified gac A as an essential gene for GAS. In conclusion, GacA is an essential monomeric enzyme in GAS and representative of monomeric RmlD enzymes in Gram‐positive bacteria and a subset of Gram‐negative bacteria. These results will help future screens for novel inhibitors of dTDP‐L‐rhamnose biosynthesis. PMID:26278404

  13. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

  14. USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW

    EPA Science Inventory

    Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

  15. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    EPA Science Inventory

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  16. The Feasibility Study of Persulfate Oxidation to Regenerating of Spent Granular Activated Carbon

    EPA Science Inventory

    Chemical oxidation is a developing technology used to regenerate contaminant-spent GAC. Chemical regeneration of GAC represents a viable option to thermal regeneration methods that are energy intensive resulting in significant consumption of fossil fuels and production of greenho...

  17. Characterization of carbon cryogel microspheres as adsorbents for VOC.

    PubMed

    Yamamoto, Takuji; Kataoka, Sho; Ohmori, Takao

    2010-05-15

    Adsorption characteristics of carbon cryogel microspheres (CC microspheres) with controlled porous structure composed of mesopores (2 nmactivated carbon (GAC) with numerous micropores, indicating that toluene is adsorbed more strongly on CC microspheres than on GAC. To permit the practical use of CC microspheres, the adsorption characteristic of moisture on CC microspheres and GAC were evaluated. The effect of adsorption of moisture on the gas permeation property of an adsorption module prepared from the CC microspheres was also examined. PMID:20042276

  18. EFFECT OF MOLECULAR OXYGEN ON THE SCALEUP OF GAC ADSORBERS

    EPA Science Inventory

    A rapid small-scale column test (RSSCT), designed according to the assumption of no dependency of the intraparticle surface diffusion coefficient on the activated carbon particle size, was able to accurately predict breakthrough of three volatile organic chemicals as well as back...

  19. Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

    2013-04-01

    Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

  20. Evaluation of the removal of antiestrogens and antiandrogens via ozone and granular activated carbon using bioassay and fluorescent spectroscopy.

    PubMed

    Ma, Dehua; Chen, Lujun; Wu, Yuchao; Liu, Rui

    2016-06-01

    Antiestrogens and antiandrogens are relatively rarely studied endocrine disrupting chemicals which can be found in un/treated wastewaters. Antiestrogens and antiandrogens in the wastewater treatment effluents could contribute to sexual disruption of organisms. In this study, to assess the removal of non-specific antiestrogens and antiandrogens by advanced treatment processes, ozonation and adsorption to granular activated carbon (GAC), the biological activities and excitation emission matrix fluorescence spectroscopy of wastewater were evaluated. As the applied ozone dose increased to 12 mg/L, the antiestrogenic activity dramatically decreased to 3.2 μg 4-hydroxytamoxifen equivalent (4HEQ)/L, with a removal efficiency of 84.8%, while the antiandrogenic activity was 23.1 μg flutamide equivalent (FEQ)/L, with a removal efficiency of 75.5%. The removal of antiestrogenic/antiandrogenic activity has high correlation with the removal of fulvic acid-like materials and humic acid-like organics, suggesting that they can be used as surrogates for antiestrogenic/antiandrogenic activity during ozonation. The adsorption kinetics of antiestrogenic activity and antiandrogenic activity were well described by pseudo-second-order kinetics models. The estimated equilibrium concentration of antiestrogenic activity is 7.9 μg 4HEQ/L with an effective removal efficiency of 70.5%, while the equilibrium concentration of antiandrogenic activity is 33.7 μg FEQ/L with a removal efficiency of 67.0%. Biological activity evaluation of wastewater effluents is an attractive way to assess the removal of endocrine disrupting chemicals by different treatment processes. Fluorescence spectroscopy can be used as a surrogate measure of bioassays during ozonation. PMID:27027562

  1. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄.

  2. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄. PMID:27483572

  3. Lon protease negatively affects GacA protein stability and expression of the Gac/Rsm signal transduction pathway in Pseudomonas protegens.

    PubMed

    Takeuchi, Kasumi; Tsuchiya, Wataru; Noda, Naomi; Suzuki, Rintaro; Yamazaki, Toshimasa; Haas, Dieter

    2014-08-01

    In Pseudomonas protegens CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway controls secondary metabolism and suppression of fungal root pathogens via the expression of regulatory small RNAs (sRNAs). Because of its high cost, this pathway needs to be protected from overexpression and to be turned off in response to environmental stress such as the lack of nutrients. However, little is known about its underlying molecular mechanisms. In this study, we demonstrated that Lon protease, a member of the ATP-dependent protease family, negatively regulated the Gac/Rsm cascade. In a lon mutant, the steady-state levels and the stability of the GacA protein were significantly elevated at the end of exponential growth. As a consequence, the expression of the sRNAs RsmY and RsmZ and that of dependent physiological functions such as antibiotic production were significantly enhanced. Biocontrol of Pythium ultimum on cucumber roots required fewer lon mutant cells than wild-type cells. In starved cells, the loss of Lon function prolonged the half-life of the GacA protein. Thus, Lon protease is an important negative regulator of the Gac/Rsm signal transduction pathway in P. protegens.

  4. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    NASA Astrophysics Data System (ADS)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  5. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  6. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies.

  7. Radiochemical Analyses of the Filter Cake, Granular Activated Carbon, and Treated Ground Water from the DTSC Stringfellow Superfund Site Pretreatment Plant

    SciTech Connect

    Esser, B K; McConachie, W; Fischer, R; Sutton, M; Szechenyi, S

    2005-09-16

    The Department of Toxic Substance Control (DTSC) requested that Lawrence Livermore National Laboratory (LLNL) evaluate the treatment process currently employed at the Department's Stringfellow Superfund Site Pretreatment Plant (PTP) site to determine if wastes originating from the site were properly managed with regards to their radioactivity. In order to evaluate the current management strategy, LLNL suggested that DTSC characterize the effluents from the waste treatment system for radionuclide content. A sampling plan was developed; samples were collected and analyzed for radioactive constituents. Following is brief summary of those results and what implications for waste characterization may be made. (1) The sampling and analysis provides strong evidence that the radionuclides present are Naturally Occurring Radioactive Material (NORM). (2) The greatest source of radioactivity in the samples was naturally occurring uranium. The sample results indicate that the uranium concentration in the filter cake is higher than the Granular Activated Carbon (GAC) samples. (11 -14 and 2-6 ppm respectively). (3) No radiologic background for geologic materials has been established for the Stringfellow site, and comprehensive testing of the process stream has not been conducted. Without site-specific testing of geologic materials and waste process streams, it is not possible to conclude if filter cake and spent GAC samples contain radioactivity concentrated above natural background levels, or if radionuclides are being concentrated by the waste treatment process. Recommendation: The regulation of Technologically Enhanced, Naturally Occurring Radioactive Materials (T-NORM) is complex. Since the results of this study do not conclusively demonstrate that natural radioactive materials have not been concentrated by the treatment process it is recommended that the DTSC consult with the Department of Health Services (DHS) Radiological Health Branch to determine if any further action is

  8. Toluene removal from waste air stream by the catalytic ozonation process with MgO/GAC composite as catalyst.

    PubMed

    Rezaei, Fatemeh; Moussavi, Gholamreza; Bakhtiari, Alireza Riyahi; Yamini, Yadollah

    2016-04-01

    This paper investigates the catalytic potential of MgO/GAC composite for toluene elimination from waste air in the catalytic ozonation process (COP). The MgO/GAC composite was a micro-porous material with the BET surface area of 1082m(2)/g. Different functional groups including aromatic CC, saturated CO of anhydrates, hydroxyl groups and SH bond of thiols were identified on the surface of MgO/GAC. Effects of residence time (0.5-4s), inlet toluene concentration (100-400ppmv) and bed temperature (25-100°C) were investigated on degradation of toluene in COP. Impregnation of GAC with MgO increased the breakthrough time and removal capacity by 73.9% and 64.6%, respectively, at the optimal conditions. The catalytic potential of the GAC and MgO/GAC for toluene degradation was 11.1% and 90.6%, respectively, at the optimum condition. The highest removal capacity using MgO/GAC (297.9gtoulene/gMgO/GAC) was attained at 100°C, whereas the highest removal capacity of GAC (128.5mgtoulene/gGAC) was obtained at 25°C. Major by-products of the toluene removal in COP with GAC were Formic acid, benzaldehyde, O-nitro-p-cresol and methyl di-phenyl-methane. MgO/GAC could greatly catalyze the decomposition of toluene in COPand formic acid was the main compound desorbed from the catalyst. Accordingly, the MgO/GAC is an efficient material to catalyze the ozonation of hydrocarbon vapors. PMID:26784452

  9. Less-costly activated carbon for sewage treatment

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Kalvinskas, J. J.; Mueller, W. A.

    1977-01-01

    Lignite-aided sewage treatment is based on absorption of dissolved pollutants by activated carbon. Settling sludge is removed and dried into cakes that are pyrolyzed with lignites to yield activated carbon. Lignite is less expensive than activated carbon previously used to supplement pyrolysis yield.

  10. Hierarchically structured activated carbon for ultracapacitors

    PubMed Central

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g−1, exhibited an extremely high specific capacitance of 157 F g−1 (95 F cc−1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors. PMID:26878820

  11. Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment.

    PubMed

    Hai, Faisal Ibney; Yamamoto, Kazuo; Nakajima, Fumiyuki; Fukushi, Kensuke

    2011-03-01

    The long-term performance of a bioaugmented membrane bioreactor (MBR) containing a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally different azo dyes was observed. A unique feeding strategy, consistent with the mode of evolution of separate waste streams in textile plants, was adopted to make the best use of the GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the colorless media was simultaneously fed through the aerobic zone. Preliminary experiments confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness of the process under gradually increasing dye-loading was tested. The respective average dye concentrations (mg/L) in the sample from GAC-zone and the membrane-permeate under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate (0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were 3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during a period of over 7 months under extremely high dye-loadings demonstrated the superiority of the proposed hybrid process.

  12. Vibration damping with active carbon fiber structures

    NASA Astrophysics Data System (ADS)

    Neugebauer, Reimund; Kunze, Holger; Riedel, Mathias; Roscher, Hans-Jürgen

    2007-04-01

    This paper presents a mechatronic strategy for active reduction of vibrations on machine tool struts or car shafts. The active structure is built from a carbon fiber composite with embedded piezofiber actuators that are composed of piezopatches based on the Macro Fiber Composite (MFC) technology, licensed by NASA and produced by Smart Material GmbH in Dresden, Germany. The structure of these actuators allows separate or selectively combined bending and torsion, meaning that both bending and torsion vibrations can be actively absorbed. Initial simulation work was done with a finite element model (ANSYS). This paper describes how state space models are generated out of a structure based on the finite element model and how controller codes are integrated into finite element models for transient analysis and the model-based control design. Finally, it showcases initial experimental findings and provides an outlook for damping multi-mode resonances with a parallel combination of resonant controllers.

  13. Charcoal and activated carbon at elevated pressure

    SciTech Connect

    Antal, M.J. Jr.; Dai, Xiangfeng; Norberg, N.

    1995-12-01

    High quality charcoal has been produced with very high yields of 50% to 60% from macadamia nut and kukui nut shells and of 44% to 47% from Eucalyptus and Leucaena wood in a bench scale unit at elevated pressure on a 2 to 3 hour cycle, compared to commercial practice of 25% to 30% yield on a 7 to 12 day operating cycle. Neither air pollution nor tar is produced by the process. The effects of feedstock pretreatments with metal additives on charcoal yield are evaluated in this paper. Also, the influences of steam and air partial pressure and total pressure on yields of activated carbon from high yield charcoal are presented.

  14. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  15. Production of activated carbon from TCR char

    NASA Astrophysics Data System (ADS)

    Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

    2016-04-01

    The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

  16. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, the principal objective of this work was to characterize and utilize the unburned carbon in fly ash for the production of activated carbons. The unburned carbon samples were collected from different combustion systems, including pulverized utility boilers, a utility cyclone, a stoker, and a fluidized bed combustor. LOI (loss-on-ignition), proximate, ultimate, and petrographic analyses were conducted, and the surface areas of the samples were characterized by N2 adsorption isotherms at 77K. The LOIs of the unburned carbon samples varied between 21.79-84.52%. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt %), while the volatile matter contents varied between 0.45 to 24.82 wt%. The elemental analyses show that all the unburned carbon samples consist mainly of carbon with very little hydrogen, nitrogen, sulfur and oxygen In addition, the potential use of unburned carbon as precursor for activated carbon (AC) was investigated. Activated carbons with specific surface area up to 1075m{sup 2}/g were produced from the unburned carbon. The porosity of the resultant activated carbons was related to the properties of the unburned carbon feedstock and the activation conditions used. It was found that not all the unburned carbon samples are equally suited for activation, and furthermore, their potential as activated carbons precursors could be

  17. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    NASA Astrophysics Data System (ADS)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  18. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-05-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  19. Activated Carbon Composites for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Tsouris, Costas; Burchell, Timothy D

    2011-09-01

    Coal-derived synthesis gas is a potential major source of hydrogen for fuel cells. Oxygen-blown coal gasification is an efficient approach to achieving the goal of producing hydrogen from coal, but a cost-effective means of enriching O2 concentration in air is required. A key objective of this project is to assess the utility of a system that exploits porous carbon materials and electrical swing adsorption to produce an O2-enriched air stream for coal gasification. As a complement to O2 and N2 adsorption measurements, CO2 was used as a more sensitive probe molecule for the characterization of molecular sieving effects. To further enhance the potential of activated carbon composite materials for air separation, work was implemented on incorporating a novel twist into the system; namely the addition of a magnetic field to influence O2 adsorption, which is accompanied by a transition between the paramagnetic and diamagnetic states. The preliminary findings in this respect are discussed.

  20. Highly porous activated carbons prepared from carbon rich Mongolian anthracite by direct NaOH activation

    NASA Astrophysics Data System (ADS)

    Byamba-Ochir, Narandalai; Shim, Wang Geun; Balathanigaimani, M. S.; Moon, Hee

    2016-08-01

    Highly porous activated carbons (ACs) were prepared from Mongolian raw anthracite (MRA) using sodium hydroxide as an activation agent by varying the mass ratio (powdered MRA/NaOH) as well as the mixing method of chemical agent and powdered MRA. The specific BET surface area and total pore volume of the prepared MRA-based activated carbons (MACs) are in the range of 816-2063 m2/g and of 0.55-1.61 cm3/g, respectively. The pore size distribution of MACs show that most of the pores are in the range from large micropores to small mesopores and their distribution can be controlled by the mass ratio and mixing method of the activating agent. As expected from the intrinsic property of the MRA, the highly graphitic surface morphology of prepared carbons was confirmed from Raman spectra and transmission electron microscopy (TEM) studies. Furthermore the FTIR and XPS results reveal that the preparation of MACs with hydrophobic in nature is highly possible by controlling the mixing conditions of activating agent and powdered MRA. Based on all the results, it is suggested that the prepared MACs could be used for many specific applications, requiring high surface area, optimal pore size distribution, proper surface hydrophobicity as well as strong physical strength.

  1. Characterization of Activated Carbons from Oil-Palm Shell by CO2 Activation with No Holding Carbonization Temperature

    PubMed Central

    Herawan, S. G.; Hadi, M. S.; Ayob, Md. R.; Putra, A.

    2013-01-01

    Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced. PMID:23737721

  2. GacS-dependent production of 2R, 3R-butanediol by Pseudomonas chlororaphis O6 is a major determinant for eliciting systemic resistance against Erwinia carotovora but not against Pseudomonas syringae pv. tabaci in tobacco.

    PubMed

    Han, Song Hee; Lee, Seung Je; Moon, Jae Hak; Park, Keun Hyung; Yang, Kwang Yeol; Cho, Balk Ho; Kim, Kil Yong; Kim, Yong Whan; Lee, Myung Chul; Anderson, Anne J; Kim, Young Cheol

    2006-08-01

    Root colonization by a plant-beneficial rhizobacterium, Pseudomonas chlororaphis O6, induces disease resistance in tobacco against leaf pathogens Erwinia carotovora subsp. carotovora SCC1, causing soft-rot, and Pseudomonas syringae pv. tabaci, causing wildfire. In order to identify the bacterial determinants involved in induced systemic resistance against plant diseases, extracellular components produced by the bacterium were fractionated and purified. Factors in the culture filtrate inducing systemic resistance were retained in the aqueous fraction rather than being partitioned into ethyl acetate. Fractionation on high-performance liquid chromatography followed by nuclear magnetic resonance mass spectrometry analysis identified the active compound as 2R, 3R-butanediol. 2R, 3R butanediol induced systemic resistance in tobacco to E. carotovora subsp. carotovora SCC1, but not to P. syringae pv. tabaci. Treatment of tobacco with the volatile 2R, 3R-butanediol enhanced aerial growth, a phenomenon also seen in plants colonized by P. chlororaphis O6. The isomeric form of the butanediol was important because 2S, 3S-butandiol did not affect the plant. The global sensor kinase, GacS, of P. chlororaphis O6 was a key regulator for induced systemic resistance against E. carotovora through regulation of 2R, 3R-butanediol production. This is the first report of the production of these assumed fermentation products by a pseudomonad and the role of the sensor kinase GacS in production of 2R, 3R-butanediol. PMID:16903358

  3. Record Methane Storage in Monolithic and Powdered Activated Carbons

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Nordwald, E.; Hester, B.; Romanos, J.; Isaacson, B.; Stalla, D.; Moore, D.; Kraus, M.; Burress, J.; Dohnke, E.; Pfeifer, P.

    2010-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically and volumetrically. Record methane storage capacities of 250 g CH4/kg carbon and 130 g CH4/liter carbon at 35 bar and 293 K have been achieved. BET surface area, porosity, and pore size distributions were measured from sub-critical nitrogen isotherms. Pore entrances were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths, was tested in Kansas City.

  4. Synthesis of fluorescent carbon nanoparticles directly from active carbon via a one-step ultrasonic treatment

    SciTech Connect

    Li, Haitao; He, Xiaodie; Liu, Yang; Yu, Hang; Kang, Zhenhui; Lee, Shuit-Tong

    2011-01-15

    Water-soluble fluorescent carbon nanoparticles were synthesized directly from active carbon by a one-step hydrogen peroxide-assisted ultrasonic treatment. The carbon nanoparticles were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer. The results showed that the surface of carbon nanoparticles was rich of hydroxyl groups resulting in high hydrophilicity. The carbon nanoparticles could emit bright and colorful photoluminescence covering the entire visible-to-near infrared spectral range. Furthermore, these carbon nanoparticles also had excellent up-conversion fluorescent properties.

  5. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  6. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  7. Fe/S doped granular activated carbon as a highly active heterogeneous persulfate catalyst toward the degradation of Orange G and diethyl phthalate.

    PubMed

    Pu, Mengjie; Ma, Yongwen; Wan, Jinquan; Wang, Yan; Huang, Mingzhi; Chen, Yangmei

    2014-03-15

    Fe/S doped granular activated carbon (Fe/SGAC) was synthesized with ferric nitrate, Na2S2O3 and (NH4)2S2O8 via an impregnation-precipitation, reduction-oxidation combining with aqueous-phase synthesis method treatment. Surface density of functional groups, surface area changes as well as the chemical state inside Fe/SGAC catalyst were studied by Boehm titration, N2 adsorption and X-ray photoelectron spectroscopy (XPS). The reactivity of the catalysts was tested by degrading Orange G (OG) and diethyl phthalate (DEP). The Fe/SGAC catalysts could significantly enhance the removal rate of OG as compared to persulfate alone and PS/GAC. And the catalytic capacity was also enhanced by S doping. But the degradation of DEP under the similar condition was inhibited by adsorption process because of the different hydrophobicities of OG and DEP molecule. Fe2O3/FeOOH (Fe(3+)) (represents ferrihydrite) together with FeO/Fe3O4 (Fe(2+)) and Fe2O3-satellite, which provide the new active site for persulfate catalyst was found to be the major components of iron element in Fe/SGAC catalyst; the existence of FeS2(S(-)) for sulfur element verified the assumption that the doped S element promoted the electron transfer between the persulfate species and iron oxide at the interface. COD removal experiment further confirmed that mostly contaminant removal was owed to the Fe/SGAC catalytic persulfate oxidation process. PMID:24461853

  8. JPL Activated Carbon Treatment System (ACTS) for sewage

    NASA Technical Reports Server (NTRS)

    1976-01-01

    An Activated Carbon Treatment System (ACTS) was developed for sewage treatment and is being applied to a one-million gallon per day sewage treatment pilot plant in Orange County California. Activities reported include pyrolysis and activation of carbon-sewage sludge, and activated carbon treatment of sewage to meet ocean discharge standards. The ACTS Sewage treatment operations include carbon-sewage treatment, primary and secondary clarifiers, gravity (multi-media) filter, filter press dewatering, flash drying of carbon-sewage filter cake, and sludge pyrolysis and activation. Tests were conducted on a laboratory scale, 10,000 gallon per day demonstration plant and pilot test equipment. Preliminary economic studies are favorable to the ACTS process relative to activated sludge treatment for a 175,000,000 gallon per day sewage treatment plant.

  9. Activated Carbon Modified with Copper for Adsorption of Propanethiol

    PubMed Central

    Moreno-Piraján, Juan Carlos; Tirano, Joaquín; Salamanca, Brisa; Giraldo, Liliana

    2010-01-01

    Activated carbons were characterized texturally and chemically before and after treatment, using surface area determination in the BET model, Boehm titration, TPR, DRX and immersion calorimetry. The adsorption capacity and the kinetics of sulphur compound removal were determined by gas chromatography. It was established that the propanethiol retention capacity is dependent on the number of oxygenated groups generated on the activated carbon surface and that activated carbon modified with CuO at 0.25 M shows the highest retention of propanethiol. Additionally is proposed a mechanism of decomposition of propenothiol with carbon-copper system. PMID:20479992

  10. Preparation of nitrogen-enriched activated carbons from brown coal

    SciTech Connect

    Robert Pietrzak; Helena Wachowska; Piotr Nowicki

    2006-05-15

    Nitrogen-enriched activated carbons were prepared from a Polish brown coal. Nitrogen was introduced from urea at 350{sup o}C in an oxidizing atmosphere both to carbonizates obtained at 500-700{sup o}C and to activated carbons prepared from them. The activation was performed at 800{sup o}C with KOH in argon. It has been observed that the carbonization temperature determines the amount of nitrogen that is incorporated (DC5U, 8.4 wt % N{sup daf}; DC6U, 6.3 wt % N{sup daf}; and DC7U, 5.4 wt % N{sup daf}). X-ray photoelectron spectroscopy (XPS) measurements have shown that nitrogen introduced both at the stage of carbonizates and at the stage of activated carbons occurs mainly as -6, -5, and imine, amine and amide groups. On the other hand, the activation of carbons enriched with nitrogen results in the formation of pyridonic nitrogen and N-Q. The introduction of nitrogen at the activated carbon stage leads to a slight decrease in surface area. It has been proven that the most effective way of preparing microporous activated carbons enriched with nitrogen to a considerable extent and having high surface area ({approximately} 3000 m{sup 2}/g) is the following: carbonization - activation - reaction with urea. 40 refs., 1 fig., 6 tabs.

  11. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The process of manufacturing a carbonized and activated nonwoven made by cotton fiber was investigated in this paper. The study was focused on the acoustic application and nonwoven composites with cotton nonwoven as a base layer and glass fiber nonwoven, cotton nonwoven, and carbonized and activated...

  12. A Magnesium-Activated Carbon Hybrid Capacitor

    SciTech Connect

    Yoo, HD; Shterenberg, I; Gofer, Y; Doe, RE; Fischer, CC; Ceder, G; Aurbach, D

    2013-12-11

    Prototype cells of hybrid capacitor were developed, comprising activated carbon (AC) cloth and magnesium (Mg) foil as the positive and negative electrodes, respectively. The electrolyte solution included ether solvent (TBF) and a magnesium organo-halo-aluminate complex 0.25 M Mg2Cl3+-Ph2AlCl2-. In this solution Mg can be deposited/dissolved reversibly for thousands of cycles with high reversibility (100% cycling efficiency). The main barrier for integrating porous AC electrodes with this electrolyte solution was the saturation of the pores with the large ions in the AC prior to reaching the potential limit. This is due to the existence of bulky Mg and Al based ionic complexes consisting Cl, alkyl or aryl (R), and THF ligands. This problem was resolved by adding 0.5 M of lithium chloride (LiCl), thus introducing smaller ionic species to the solution. This Mg hybrid capacitor system demonstrated a stable cycle performance for many thousands of cycles with a specific capacitance of 90 Fg(-1) for the AC positive electrodes along a potential range of 2.4 V. (C) 2014 The Electrochemical Society. All rights reserved.

  13. Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions

    NASA Astrophysics Data System (ADS)

    Allison, S. D.; Jastrow, J. D.

    2004-12-01

    Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

  14. 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.

  15. Fractal analysis of granular activated carbons using isotherm data

    SciTech Connect

    Khalili, N.R.; Pan, M.; Sandi, G.

    1997-08-01

    Utilization of adsorption on solid surfaces was exercised for the first time in 1785. Practical application of unactivated carbon filters, and powdered carbon were first demonstrated in the American water treatment plant, and a municipal treatment plant in New Jersey, in 1883 and 1930, respectively. The use of activated carbon became widespread in the next few decades. At present, adsorption on carbons has a wide spread application in water treatment and removal of taste, odor, removal of synthetic organic chemicals, color-forming organics, and desinfection by-products and their naturally occurring precursors. This paper presents an analysis of the surface fractal dimension and adsorption capacity of a group of carbons.

  16. Selecting activated carbon for water and wastewater treatability studies

    SciTech Connect

    Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C.

    2007-10-15

    A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

  17. The GacS/A-RsmA Signal Transduction Pathway Controls the Synthesis of Alkylresorcinol Lipids that Replace Membrane Phospholipids during Encystment of Azotobacter vinelandii SW136

    PubMed Central

    Romero, Yanet; Guzmán, Josefina; Moreno, Soledad; Cocotl-Yañez, Miguel; Vences-Guzmán, Miguel Ángel; Castañeda, Miguel; Espín, Guadalupe; Segura, Daniel

    2016-01-01

    Azotobacter vinelandii is a soil bacterium that undergoes a differentiation process that forms cysts resistant to desiccation. During encystment, a family of alkylresorcinols lipids (ARs) are synthesized and become part of the membrane and are also components of the outer layer covering the cyst, where they play a structural role. The synthesis of ARs in A. vinelandii has been shown to occur by the activity of enzymes encoded in the arsABCD operon. The expression of this operon is activated by ArpR, a LysR-type transcriptional regulator whose transcription occurs during encystment and is dependent on the alternative sigma factor RpoS. In this study, we show that the two component response regulator GacA, the small RNA RsmZ1 and the translational repressor protein RsmA, implicated in the control of the synthesis of other cysts components (i.e., alginate and poly-ß-hydroxybutyrate), are also controlling alkylresorcinol synthesis. This control affects the expression of arsABCD and is exerted through the regulation of arpR expression. We show that RsmA negatively regulates arpR expression by binding its mRNA, repressing its translation. GacA in turn, positively regulates arpR expression through the activation of transcription of RsmZ1, that binds RsmA, counteracting its repressor activity. This regulatory cascade is independent of RpoS. We also show evidence suggesting that GacA exerts an additional regulation on arsABCD expression through an ArpR independent route. PMID:27055016

  18. Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl 2 activation

    NASA Astrophysics Data System (ADS)

    Uçar, Suat; Erdem, Murat; Tay, Turgay; Karagöz, Selhan

    2009-08-01

    In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl 2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m 2 g -1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m 2 g -1 and 0.329 cm 3 g -1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature.

  19. Grain-based activated carbons for natural gas storage.

    PubMed

    Zhang, Tengyan; Walawender, Walter P; Fan, L T

    2010-03-01

    Natural gas has emerged as a potential alternative to gasoline due to the increase in global energy demand and environmental concerns. An investigation was undertaken to explore the technical feasibility of implementing the adsorbed natural gas (ANG) storage in the fuel tanks of motor vehicles with activated carbons from biomass, e.g., sorghum and wheat. The grain-based activated carbons were prepared by chemical activation; the experimental parameters were varied to identify the optimum conditions. The porosity of the resultant activated carbons was evaluated through nitrogen adsorption; and the storage capacity, through methane adsorption. A comparative study was also carried out with commercial activated carbons from charcoal. The highest storage factor attained was 89 for compacted grain-based activated carbons from grain sorghum with a bulk density of 0.65 g/cm(3), and the highest storage factor attained is 106 for compacted commercial activated carbons (Calgon) with a bulk density of 0.70 g/cm(3). The storage factor was found to increase approximately linearly with increasing bulk density and to be independent of the extent of compaction. This implies that the grain-based activated carbons are the ideal candidates for the ANG storage.

  20. Impact of sulfur oxides on mercury capture by activated carbon.

    PubMed

    Presto, Albert A; Granite, Evan J

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACl, mercury capture was tested under varying conditions of SO2 and SO3 concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface.

  1. Impact of Sulfur Oxides on Mercury Capture by Activated Carbon

    SciTech Connect

    Presto, A.A.; Granite, E.J.

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACI, mercury capture was tested under varying conditions of SO2 and SO3 concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface.

  2. CCN activation of pure and coated carbon black particles.

    PubMed

    Dusek, U; Reischl, G P; Hitzenberger, R

    2006-02-15

    The CCN (cloud condensation nucleus) activation of pure and coated carbon black particles was investigated using the University of Vienna cloud condensation nuclei counter (Giebl, H.; Berner, A.; Reischl, G.; Puxbaum, H.; Kasper-Giebl, A.; Hitzenberger, R. J. Aerosol Sci. 2002, 33, 1623-1634). The particles were produced by nebulizing an aqueous suspension of carbon black in a Collison atomizer. The activation of pure carbon black particles was found to require higher supersaturations than predicted by calculations representing the particles as insoluble, wettable spheres with mobility equivalent diameter. To test whether this effect is an artifact due to heating of the light-absorbing carbon black particles in the laser beam, experiments at different laser powers were conducted. No systematic dependence of the activation of pure carbon black particles on laser power was observed. The observations could be modeled using spherical particles and an effective contact angle of 4-6 degrees of water at their surface. The addition of a small amount of NaCl to the carbon black particles (by adding 5% by mass NaCl to the carbon black suspension) greatly enhanced their CCN efficiency. The measured CCN efficiencies were consistent with Kohler theory for particles consisting of insoluble and hygroscopic material. However, coating the carbon black particles with hexadecanol (a typical film-forming compound with one hydrophobic and one hydrophilic end) efficiently suppressed the CCN activation of the carbon black particles.

  3. Soil Inorganic Carbon in Deserts: Active Carbon Sink or Inert Reservoir?

    NASA Astrophysics Data System (ADS)

    Monger, H. C.; Cole, D. R.

    2011-12-01

    Soil inorganic carbon is the third largest C pool in the active global carbon cycle, containing at least 800 petagrams of carbon. Although carbonate dissolution-precipitation reactions have been understood for over a century, the role of soil inorganic carbon in carbon sequestration, and in particular pedogenic carbonate, is a deceptively complex process because it involves interdependent connections among climate, plants, microorganisms, silicate minerals, soil moisture, pH, and Ca supply via rain, dust, or in situ weathering. An understanding of soil inorganic carbon as a sink or reservoir also requires examination of the system at local to continental scales and at seasonal to millennial time scales. In desert soils studied in North America, carbon isotope ratios and radiocarbon dates were measured in combination with electron microscopy, lab and field experiments with biological calcite formation, and field measurements of carbon dioxide emissions. These investigations reveal that soil inorganic carbon is both an active sink and a inert reservoir depending on the spatial and temporal scale and source of calcium.

  4. Role of nitrogen in pore development in activated carbon prepared by potassium carbonate activation of lignin

    NASA Astrophysics Data System (ADS)

    Tsubouchi, Naoto; Nishio, Megumi; Mochizuki, Yuuki

    2016-05-01

    The present work focuses on the role of nitrogen in the development of pores in activated carbon produced from lignin by K2CO3 activation, employing a fixed bed reactor under a high-purity He stream at temperatures of 500-900 °C. The specific surface area and pore volume obtained by activation of lignin alone are 230 m2/g and 0.13 cm3/g at 800 °C, and 540 m2/g and 0.31 cm3/g at 900 °C, respectively. Activation of a mixture of lignin and urea provides a significant increase in the surface area and volume, respectively reaching 3300-3400 m2/g and 2.0-2.3 cm3/g after holding at 800-900 °C for 1 h. Heating a lignin/urea/K2CO3 mixture leads to a significant decrease in the yield of released N-containing gases compared to the results for urea alone and a lignin/urea mixture, and most of the nitrogen in the urea is retained in the solid phase. X-ray photoelectron spectroscopy and X-ray diffraction analyses clearly show that part of the remaining nitrogen is present in heterocyclic structures (for example, pyridinic and pyrrolic nitrogen), and the rest is contained as KOCN at ≤600 °C and as KCN at ≥700 °C, such that the latter two compounds can be almost completely removed by water washing. The fate of nitrogen during heating of lignin/urea/K2CO3 and role of nitrogen in pore development in activated carbon are discussed on the basis of the results mentioned above.

  5. Ocean bottom sediments as an active carbon pool.

    NASA Astrophysics Data System (ADS)

    Zimov, N.; Zimov, S. A.

    2015-12-01

    Bottom deposits of oceans, seas and lakes are long term carbon sinks - particulate organic carbon falls to the bottom where it is covered by sediments and preserved by anoxic conditions. However, the upper horizons of these deep sediments ('active layer') interact with bottom waters through diffusion, bubbling of gasses and bioturbation and can thus also act as temporary carbon sources given favorable environment conditions. Oxygen diffusion is the main factor that limits organic decomposition in bottom deposits. Depth of diffusion depends on porosity of sediments and rates of oxygen consumption in the upper horizons. Amplified organic rain leads to higher oxygen demand and, consequently, to a thinner oxic horizon in the bottom sediments. Declined ocean productivity, in contrast, allows oxygen to diffuse deeper into the bottom sediments and remobilizes previously preserved carbon. Therefore a substantial decline in ocean productivity during glacial periods could cause ocean sediments to shift abruptly from a carbon sink to a considerable carbon source. To estimate the effects of the phenomena described above, we present a model of the dynamics and vertical distribution of organic carbon in ocean sediments that considers the input of organic rain, sediments porosity, oxygen availability, rates of sedimentation to the ocean floor and bioturbation. The model enables quantification of bulk carbon storage, carbon distribution within the 'active layer', and the flux of carbon from the upper sediment horizons to deeper deposits as sediments accumulate on the ocean floor. Applying our model, we find that during glacial periods, decreased ocean productivity led to the mobilization of old carbon previously stored within anoxic horizons. Under this scenario, carbon transfer from sediments to ocean waters would have exceeded 10 kg/m2. Our study therefore, suggests that the ocean floor is not merely a passive buffer in the global carbon cycle, but instead an active pool which

  6. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants. PMID:27214000

  7. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants.

  8. Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process.

    PubMed

    Dong, Lihua; Liu, Wenjun; Jiang, Renfu; Wang, Zhansheng

    2014-11-01

    The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10 μm) volume and the increase of mesopore and macropore (0.1 μm

  9. JV Task 90 - Activated Carbon Production from North Dakota Lignite

    SciTech Connect

    Steven Benson; Charlene Crocker; Rokan Zaman; Mark Musich; Edwin Olson

    2008-03-31

    The Energy & Environmental Research Center (EERC) has pursued a research program for producing activated carbon from North Dakota lignite that can be competitive with commercial-grade activated carbon. As part of this effort, small-scale production of activated carbon was produced from Fort Union lignite. A conceptual design of a commercial activated carbon production plant was drawn, and a market assessment was performed to determine likely revenue streams for the produced carbon. Activated carbon was produced from lignite coal in both laboratory-scale fixed-bed reactors and in a small pilot-scale rotary kiln. The EERC was successfully able to upgrade the laboratory-scale activated carbon production system to a pilot-scale rotary kiln system. The activated carbon produced from North Dakota lignite was superior to commercial grade DARCO{reg_sign} FGD and Rheinbraun's HOK activated coke product with respect to iodine number. The iodine number of North Dakota lignite-derived activated carbon was between 600 and 800 mg I{sub 2}/g, whereas the iodine number of DARCO FGD was between 500 and 600 mg I{sub 2}/g, and the iodine number of Rheinbraun's HOK activated coke product was around 275 mg I{sub 2}/g. The EERC performed both bench-scale and pilot-scale mercury capture tests using the activated carbon made under various optimization process conditions. For comparison, the mercury capture capability of commercial DARCO FGD was also tested. The lab-scale apparatus is a thin fixed-bed mercury-screening system, which has been used by the EERC for many mercury capture screen tests. The pilot-scale systems included two combustion units, both equipped with an electrostatic precipitator (ESP). Activated carbons were also tested in a slipstream baghouse at a Texas power plant. The results indicated that the activated carbon produced from North Dakota lignite coal is capable of removing mercury from flue gas. The tests showed that activated carbon with the greatest iodine number

  10. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  11. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  12. Nickel adsorption by sodium polyacrylate-grafted activated carbon.

    PubMed

    Ewecharoen, A; Thiravetyan, P; Wendel, E; Bertagnolli, H

    2009-11-15

    A novel sodium polyacrylate grafted activated carbon was produced by using gamma radiation to increase the number of functional groups on the surface. After irradiation the capacity for nickel adsorption was studied and found to have increased from 44.1 to 55.7 mg g(-1). X-ray absorption spectroscopy showed that the adsorbed nickel on activated carbon and irradiation-grafted activated carbon was coordinated with 6 oxygen atoms at 2.04-2.06 A. It is proposed that this grafting technique could be applied to other adsorbents to increase the efficiency of metal adsorption.

  13. Grafting of activated carbon cloths for selective adsorption

    NASA Astrophysics Data System (ADS)

    Gineys, M.; Benoit, R.; Cohaut, N.; Béguin, F.; Delpeux-Ouldriane, S.

    2016-05-01

    Chemical functionalization of an activated carbon cloth with 3-aminophthalic acid and 4-aminobenzoic acid groups by the in situ formation of the corresponding diazonium salt in aqueous acidic solution is reported. The nature and amount of selected functions on an activated carbon surface, in particular the grafted density, were determined by potentiometric titration, elemental analysis and X-ray photoelectron spectroscopy (XPS). The nanotextural properties of the modified carbon were explored by gas adsorption. Functionalized activated carbon cloth was obtained at a discrete grafting level while preserving interesting textural properties and a large porous volume. Finally, the grafting homogeneity of the carbon surface and the nature of the chemical bonding were investigated using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) technique.

  14. Physical and electrochemical study of halide-modified activated carbons

    NASA Astrophysics Data System (ADS)

    Barpanda, Prabeer

    The current thesis aims to improve the electrochemical capacity of activated carbon electrodes, which enjoy prominent position in commercial electrochemical capacitors. Our approach was to develop electrochemical capacity by developing faradaic pseudocapacitance in carbon through a novel mechanochemical modification using iodine and bromine. Various commercial carbons were mechanochemically modified via solid-state iodation and vapour phase iodine-incorporation. The halidation-induced changes in the structure, composition, morphology, electrical and electrochemical properties of carbon materials were studied using different characterization techniques encompassing XRD, XRF, XPS, Raman spectroscopy, BET study, TEM, SAXS and electrochemical testing followed by an intensive battery of physical and electrochemical characterization. The introduction of iodine into carbon system led to the formation of polyiodide species that were preferentially reacted within the micropore voids within the carbon leading to the development of a faradaic reaction at 3.1V. In spite of the lower surface area of modified carbon, we observed manyfold increase in its electrochemical capacity. Parallel inception of non-faradaic development and faradaic pseudocapacitive reaction led to promising gravimetric, surface area normalized and volumetric capacity in iodated carbons. With promising electrochemical improvement post halidation process, the chemical halidation method was extended to different class of carbons and halides. Carbons ranging from amorphous (activated) carbons to crystalline carbons (graphites, fluorographites) were iodine-modified to gain further insight on the local graphite-iodine chemical interaction. In addition, the effect of pore size distribution on chemical iodation process was studied by using in-house fabricated microporous carbon. A comparative study of commercial mesoporous carbons and in-house fabricated microporous carbons showed higher iodine-uptake ability and

  15. Hydrogen storage on activated carbon. Final report

    SciTech Connect

    Schwarz, J.A.

    1994-11-01

    The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.

  16. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, W.P.; Fan, L.T.

    1996-12-31

    The term, activated carbon, is a generic name for a family of carbonaceous materials with well-developed porosities and consequently, large adsorptive capacities. Activated carbons are increasingly being consumed worldwide for environmental applications such as separation of volatiles from bulk gases and purification of water and waste-water streams. The global annual production is estimated to be around 300 million kilograms, with a rate of increase of 7% each year. Activated carbons can be prepared from a variety of raw materials. Approximately, 60% of the activated carbons generated in the United States is produced from coal; 20%, from coconut shells; and the remaining 20% from wood and other sources of biomass. The pore structure and properties of activated carbons are influenced by the nature of the starting material and the initial physical and chemical conditioning as well as the process conditions involved in its manufacture. The porous structures of charcoals and activated carbons obtained by the carbonization of kernels have been characterized.

  17. Microstructure and surface properties of lignocellulosic-based activated carbons

    NASA Astrophysics Data System (ADS)

    González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

    2013-01-01

    Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  18. Mechanism of phenol adsorption onto electro-activated carbon granules.

    PubMed

    Lounici, H; Aioueche, F; Belhocine, D; Drouiche, M; Pauss, A; Mameri, N

    2004-01-01

    The main purpose of this paper is to determine the mechanisms which govern the adsorption of the phenol onto electro-activated carbon granules. This new activation technique allowed an increase of the performance of the adsorbent. Two models were utilised to understand the improvement in the performance of electroactivated carbon granules. The first, a simple external resistance model based on film resistance, gave acceptable predictions, with an error of less than 15%, between the theoretical results and experimental data independent of the activation potential and phenol initial concentration. The second linear model, based on diffusion phenomena, was more representative in describing the experiment than the first model. It was observed that the electro-activation method did not change the mechanism which governs phenol adsorption onto granular carbon. Indeed, the same mathematical model based on diffusion phenomena made it possible to predict with a very low error (less than 5%) the experimental data obtained for the favourable activation potential, without activation potential and with an unfavourable activation potential. The electro-activation technique makes it possible to increase the number of active sites that improve the performance of the electro-activated granular carbon compared with conventional granular activated carbon.

  19. Selection and preparation of activated carbon for fuel gas storage

    DOEpatents

    Schwarz, James A.; Noh, Joong S.; Agarwal, Rajiv K.

    1990-10-02

    Increasing the surface acidity of active carbons can lead to an increase in capacity for hydrogen adsorption. Increasing the surface basicity can facilitate methane adsorption. The treatment of carbons is most effective when the carbon source material is selected to have a low ash content i.e., below about 3%, and where the ash consists predominantly of alkali metals alkali earth, with only minimal amounts of transition metals and silicon. The carbon is washed in water or acid and then oxidized, e.g. in a stream of oxygen and an inert gas at an elevated temperature.

  20. TESTING GUIDELINES FOR TECHNETIUM-99 ABSORPTION ON ACTIVATED CARBON

    SciTech Connect

    BYRNES ME

    2010-09-08

    CH2M HILL Plateau Remediation Company (CHPRC) is currently evaluating the potential use of activated carbon adsorption for removing technetium-99 from groundwater as a treatment method for the Hanford Site's 200 West Area groundwater pump-and-treat system. The current pump-and-treat system design will include an ion-exchange (IX) system for selective removal of technetium-99 from selected wells prior to subsequent treatment of the water in the central treatment system. The IX resin selected for technetium-99 removal is Purolite A530E. The resin service life is estimated to be approximately 66.85 days at the design technetium-99 loading rate, and the spent resin must be replaced because it cannot be regenerated. The resulting operating costs associated with resin replacement every 66.85 days are estimated at $0.98 million/year. Activated carbon pre-treatment is being evaluated as a potential cost-saving measure to offset the high operating costs associated with frequent IX resin replacement. This document is preceded by the Literature Survey of Technetium-99 Groundwater Pre-Treatment Option Using Granular Activated Carbon (SGW-43928), which identified and evaluated prior research related to technetium-99 adsorption on activated carbon. The survey also evaluated potential operating considerations for this treatment approach for the 200 West Area. The preliminary conclusions of the literature survey are as follows: (1) Activated carbon can be used to selectively remove technetium-99 from contaminated groundwater. (2) Technetium-99 adsorption onto activated carbon is expected to vary significantly based on carbon types and operating conditions. For the treatment approach to be viable at the Hanford Site, activated carbon must be capable of achieving a designated minimum technetium-99 uptake. (3) Certain radionuclides known to be present in 200 West Area groundwater are also likely to adsorb onto activated carbon. (4) Organic solvent contaminants of concern (COCs) will

  1. Dynamic regulation of GacA in type III secretion, pectinase gene expression, pellicle formation, and pathogenicity of Dickeya dadantii (Erwinia chrysanthemi 3937).

    PubMed

    Yang, Shihui; Peng, Quan; Zhang, Qiu; Yi, Xuan; Choi, Chang Jae; Reedy, Ralph M; Charkowski, Amy O; Yang, Ching-Hong

    2008-01-01

    Dickeya dadantii (Erwinia chrysanthemi 3937) secretes exoenzymes, including pectin-degrading enzymes, leading to the loss of structural integrity of plant cell walls. A type III secretion system (T3SS) is essential for full virulence of this bacterium within plant hosts. The GacS/GacA two-component signal transduction system participates in important biological roles in several gram-negative bacteria. In this study, a gacA deletion mutant (Ech137) of D. dadantii was constructed to investigate the effect of this mutation on pathogenesis and other phenotypes. Compared with wild-type D. dadantii, Ech137 had a delayed biofilm-pellicle formation. The production of pectate lyase (Pel), protease, and cellulase was diminished in Ech137 compared with the wild-type cells. Reduced transcription of two endo-Pel genes, pelD and pelL, was found in Ech137 using a green fluorescence protein-based fluorescence-activated cell sorter promoter activity assay. In addition, the transcription of T3SS genes dspE (an effector), hrpA (a structural protein of the T3SS pilus), and hrpN (a T3SS harpin) was reduced in Ech137. A lower amount of rsmB regulatory RNA was found in gacA mutant Ech137 compared with the wild-type bacterium by quantitative reverse-transcription polymerase chain reaction. Compared with wild-type D. dadantii, a lower amount of hrpL mRNA was observed in Ech137 at 12 h grown in medium. Although the role of RsmA, rsmB, and RsmC in D. dadantii is not clear, from the regulatory pathway revealed in E. carotovora, the lower expression of dspE, hrpA, and hrpN in Ech137 may be due to a post-transcriptional regulation of hrpL through the Gac-Rsm regulatory pathway. Consequently, the reduced exoenzyme production and Pel gene expression in the mutant may be sue partially to the regulatory role of rsmB-RsmA on exoenzyme expression. Similar to in vitro results, a lower expression of T3SS and pectinase genes of Ech137 also was observed in bacterial cells inoculated into Saintpaulia

  2. Complement activation and protein adsorption by carbon nanotubes.

    PubMed

    Salvador-Morales, Carolina; Flahaut, Emmanuel; Sim, Edith; Sloan, Jeremy; Green, Malcolm L H; Sim, Robert B

    2006-02-01

    As a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantity.

  3. Natural gas storage with activated carbon from a bituminous coal

    USGS Publications Warehouse

    Sun, Jielun; Rood, M.J.; Rostam-Abadi, M.; Lizzio, A.A.

    1996-01-01

    Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (<0.044 mm). The increase in Vm/Vs is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

  4. [Influence of biological activated carbon dosage on landfill leachate treatment].

    PubMed

    Cui, Yan-Rui; Guo, Yan; Wu, Qing

    2014-08-01

    Effects of biological activated carbon (BAC) dosage on COD removal in landfill leachate treatment were compared. The COD removal efficiency of reactors with 0, 100 and 300 g activated carbon dosage per litre activated sludge was 12.9%, 19.6% and 27.7%, respectively. The results indicated that BAC improved the refractory organic matter removal efficiency and there was a positive correlation between COD removal efficiency and BAC dosage. The output of carbon dioxide after 8h of aeration in reactors was 109, 193 and 306 mg corresponding to the activated carbon dosages mentioned above, which indicated the amount of biodegradation and BAC dosage also had a positive correlation. The combination of adsorption and bioregeneration of BAC resulted in the positive correlation betweem organic matter removal efficiency and BAC dosage, and bioregeneration was the root cause for the microbial decomposition of refractory organics.

  5. Treatment of MTBE by air stripping, carbon adsorption, and advanced oxidation: technical and economic comparison for five groundwaters.

    PubMed

    Sutherland, J; Adams, C; Kekobad, J

    2004-01-01

    An investigation was made of the treatability of methyl tert-butyl ether (MTBE) in five groundwaters with highly varied water quality characteristics. Air stripping, granular activated carbon (GAC) adsorption, and the O(3)/H(2)O(2) and UV/H(2)O(2) advanced oxidation processes were compared in a mobile water treatment pilot plant under a variety of process conditions. Air stripping was shown to have the lower unit treatment costs for higher flowrates (i.e., 3800L/min), although relatively tall towers were required for greater treatment requirements. At low flowrates (i.e., 38L/min), advanced oxidation provided the lowest treatment costs for four of five waters (but was ineffective for a high chemical oxygen demand water). Both the O(3)/H(2)O(2) and UV/H(2)O(2) processes were more efficient at pH 7 versus 9 due in part to increased scavenging at higher pH. GAC was examined using rapid small-scale column tests (RSSCT). GAC was effective at most conditions, although it was also the most costly alternative for most waters. The results of this study can help to provide specific guidance into process selection for treating MTBE in contaminated groundwaters.

  6. Adsorption of dichlorodifluoromethane, chlorodifluoromethane, and chloropentafluoroethane on activated carbon

    SciTech Connect

    Berlier, K.; Frere, M.; Bougard, J.

    1995-09-01

    The CFCs (chlorofluorocarbons) are used as working refrigerant fluids. Recent concerns of the effects of CFCs on the ozone layer requires the development of efficient recovery methods. One technique is to adsorb the fluids onto a porous medium such as silica gel or activated carbon. Isotherms and enthalpies of adsorption curves of dichlorodifluoromethane (R12), chlorodifluoromethane (R22), and chloropentafluoroethane (R115) on three different activated carbons have been obtained at 303 K and at pressures to 602 kPa.

  7. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    SciTech Connect

    Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

    2007-05-01

    Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

  8. Preparation and characterization of activated carbon from sugarcane bagasse by physical activation with CO2 gas

    NASA Astrophysics Data System (ADS)

    Bachrun, Sutrisno; AyuRizka, Noni; Annisa, SolichaHidayat; Arif, Hidayat

    2016-01-01

    A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, and 800oC) on characteristics of porosity in activated carbon derived from carbonized sugarcane bagassechar at activation temperature of 800oC. The results showed that the activated carbon derived from high carbonized temperature of sugarcane bagassechars had higher BET surface area, total volume, micropore volume and yield as compared to the activated carbon derived from low carbonized temperature. The BET surface area, total volume and micropore volume of activated carbon prepared from sugarcane bagassechars obtained at 800oC of carbonized temperature and activation time of 120 min were 661.46m2/g, 0.2455cm3/g and 0.1989cm3/g, respectively. The high carbonization temperature (800oC) generated a highly microporous carbonwith a Type-I nitrogen adsorption isotherm, while the low carbonization temperature (400 and 600oC) generated a mesoporous one with an intermediate between types I and IInitrogen adsorption isotherm.

  9. Production of activated carbon from rice husk Vietnam

    NASA Astrophysics Data System (ADS)

    Korobochkin, V. V.; Tu, N. V.; Hieu, N. M.

    2016-09-01

    This work is dedicated to the production of activated carbon from rice husk from Delta of the Red River in Viet Nam. At the first stage, carbonization of a rice husk was carried out to obtain material containing 43.1% carbon and 25 % silica with a specific surface area of 51.5 m2/g. After separating of silica (the second stage), the specific surface area of the product increased to 204 m2/g and the silica content decreased to 1.23% by weight as well. The most important stage in the formation of the porous structure of the material is the activation. The products with the high specific surface area in the range of 800-1345 m2/g were obtained by activation of carbonized product with water vapour or carbon dioxide at temperatures of 700 °C and 850 °C, with varying the flow rate of the activating agent and activation time. The best results were achieved by activation of carbon material with water vapour at the flow rate of 0.08 dm3/min per 500 g of material and the temperature of 850 °C.

  10. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2000-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  11. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2001-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  12. Water vapor adsorption on activated carbon preadsorbed with naphtalene.

    PubMed

    Zimny, T; Finqueneisel, G; Cossarutto, L; Weber, J V

    2005-05-01

    The adsorption of water vapor on a microporous activated carbon derived from the carbonization of coconut shell has been studied. Preadsorption of naphthalene was used as a tool to determine the location and the influence of the primary adsorbing centers within the porous structure of active carbon. The adsorption was studied in the pressure range p/p0=0-0.95 in a static water vapor system, allowing the investigation of both kinetic and equilibrium experimental data. Modeling of the isotherms using the modified equation of Do and Do was applied to determine the effect of preadsorption on the mechanism of adsorption. PMID:15797395

  13. Carbon-Carbon Bond Cleavage in Activation of the Prodrug Nabumetone

    PubMed Central

    Varfaj, Fatbardha; Zulkifli, Siti N. A.; Park, Hyoung-Goo; Challinor, Victoria L.; De Voss, James J.

    2014-01-01

    Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17β-lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O-demethylation and alcohol to ketone transformations of nabumetone and its analogs. PMID:24584631

  14. The Formation of Carbon Nanofibers on Powdered Activated Carbon Impregnated with Nickel

    NASA Astrophysics Data System (ADS)

    Ahmed, Y. M.; Al-Mamun, A. A.; Muyibi, S. A.; Al-Khatib, M. F. R.; Jameel, A. T.; AlSaadi, M. A.

    2009-06-01

    In the present work, the production and characterization of carbon nanofibers (CNFs) composite is reported. Carbon nanofibers (CNF) were produced on powdered activated carbon PAC—impregnated with nickel—by Chemical Vapor Deposition (CVD) of a hydrocarbon in the presence of hydrogen at ˜780° C. The flow rates of carbon source and hydrogen were fixed. The CNFs were formed directly over the impregnated AC. Variable weight percentage ratios of the catalyst salt (Ni+2) were used for the impregnation (1, 3, 5, 7 and 9%, respectively). The product displays a relatively high surface area, essentially constituted by the external surface, and the absence of the bottled pores encountered with activated carbon. FSEM, TEM and TGA were used for the characterization of the product.

  15. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs.

  16. Inhibition of methylation at two internal N6-methyladenosine sites caused by GAC to GAU mutations.

    PubMed

    Kane, S E; Beemon, K

    1987-03-01

    We previously have mapped N6-methyladenosine (m6A) sites within the genomic RNA of Rous sarcoma virus (RSV). The results of that study and of experiments using inhibitors of methylation suggest that m6A might be involved in mRNA processing events. We describe an approach for directly analyzing the function of m6A in RNA and for studying the sequence specificity of the m6A methylase. Two sites of methylation in RSV (nucleotides 7414 and 7424) were altered by oligonucleotide-directed mutagenesis. The highly conserved GAC consensus sequence at those sites was changed to GAU. The new sequences were no longer methylated in the RSV genomic RNA; the GAC sequence was required for efficient base modification at those two adenosines. The altered m6A pattern did not affect viral RNA processing or the viral life cycle within infected cells. PMID:3029112

  17. Mutagenic activity of disinfection by-products.

    PubMed

    Cognet, L; Courtois, Y; Mallevialle, J

    1986-11-01

    Data on raw water quality, disinfection treatment practices, and the resulting mutagenic properties of the treated water were compiled from pilot- and full-scale treatment experiments to evaluate that parameter which might produce variability in the results of a mutagenic study. Analysis of the data and comparison of treatment practices indicated that the measured mutagenic activity is strongly related to the characteristics of the organic matter in the raw water, the methodology used to sample and detect mutagens, the scale of the study both in terms of treatment flow and period of study, and the point at which and the conditions under which oxidants are added during treatment. Conclusions regarding disinfection systems in full-scale water treatment plants include the following: When raw water is pretreated and high concentrations of organics are present in the raw water, both ozonation and chlorination increased mutagenic activity. However, no significant difference in mutagenicity was found between the two oxidants. Both in the case of a nitrified groundwater and a clarified surface water, the mutagenic activity of the water after ozonation was related to its mutagenic activity before ozonation. With ozonation, mutagenic activity decreased after granular activated carbon (GAC) filtration. Thus, when GAC filtration follows ozone disinfection, early addition of oxidants may not be deleterious to the finished water quality. When chlorine or chlorine dioxide is added after GAC filtration, chlorine dioxide was found to produce a less mutagenic water than chlorine. Although these conclusions suggest means of controlling mutagenic activity during treatment, it must be stressed that the measurement of mutagenicity is a presumptive index of contamination level.

  18. Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

    2013-09-01

    In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

  19. Activated Carbon Composites for Air Separation

    SciTech Connect

    Contescu, Cristian I; Baker, Frederick S; Tsouris, Costas; McFarlane, Joanna

    2008-03-01

    In continuation of the development of composite materials for air separation based on molecular sieving properties and magnetic fields effects, several molecular sieve materials were tested in a flow system, and the effects of temperature, flow conditions, and magnetic fields were investigated. New carbon materials adsorbents, with and without pre-loaded super-paramagnetic nanoparticles of Fe3O4 were synthesized; all materials were packed in chromatographic type columns which were placed between the poles of a high intensity, water-cooled, magnet (1.5 Tesla). In order to verify the existence of magnetodesorption effect, separation tests were conducted by injecting controlled volumes of air in a flow of inert gas, while the magnetic field was switched on and off. Gas composition downstream the column was analyzed by gas chromatography and by mass spectrometry. Under the conditions employed, the tests confirmed that N2 - O2 separation occurred at various degrees, depending on material's intrinsic properties, temperature and flow rate. The effect of magnetic fields, reported previously for static conditions, was not confirmed in the flow system. The best separation was obtained for zeolite 13X at sub-ambient temperatures. Future directions for the project include evaluation of a combined system, comprising carbon and zeolite molecular sieves, and testing the effect of stronger magnetic fields produced by cryogenic magnets.

  20. Protective effect and mechanism of action of saponins isolated from the seeds of gac (Momordica cochinchinensis Spreng.) against cisplatin-induced damage in LLC-PK1 kidney cells.

    PubMed

    Jung, Kiwon; Lee, Dahae; Yu, Jae Sik; Namgung, Hojin; Kang, Ki Sung; Kim, Ki Hyun

    2016-03-01

    This study was performed to investigate the renoprotective effect and mechanism of Momordicae Semen, gac seeds, against the cisplatin-induced damage in LLC-PK1 kidney cells. In order to identify the active components, three major saponins were isolated from extract of the gac seed, gypsogenin 3-O-β-d-galactopyranosyl(1→2)-[α-L-rhamnopyranosyl(1→3)]-β-d-glucuronopyranoside (1), quillaic acid 3-O-β-D-galactopyranosyl(1→2)-[α-L-rhamnopyranosyl(1→3)]-β-D-glucuronopyranoside (2), and momordica saponin I (3). Compounds 1 and 2 ameliorated cisplatin-induced nephrotoxicity up to 80% of the control value at both 5 and 25μM. Phosphorylation of MAPKs was decreased along cisplatin treatment after treatment with compounds 1 and 2. These results show that blocking the MAPKs signaling cascade plays a critical role in mediating the renoprotective effect of Momordicae Semen extract and compounds 1 and 2.

  1. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Prof. Harold H. Schobert; Dr. M. Mercedes Maroto-Valer; Ms. Zhe Lu

    2001-09-29

    The implementation of increasingly stringent Clean Air Act Regulations by the coal utility industry has resulted in an increase in the concentration of unburned carbon in coal combustion fly ash. In 1999, around 6 million tons of unburned carbon were disposed in the US, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, this report evaluates and compares several routes for the production of activated carbons from unburned carbon, including physical activation with steam or CO{sub 2}, and chemical activation using KOH pretreatment. During the present reporting period (June 30, 2000--June 29, 2001), Task 1 ''Procurement and characterization of CCBPs'' was concluded, including samples from pulverized utility boilers, a utility cyclone unit equipped with a beneficiation technology, a suspension-fired research boiler, and a class C fly ash. The characterization studies showed that the samples collected have significantly different carbon contents, as determined by the ASTM C114 procedure, with the sample from the cyclone unit containing the highest carbon content (LOI of {approx} 80%), since this unit has been retrofitted with a technology to separate the unburned carbon from the fly ash. The porosity of the samples assembled was characterized by N{sub 2} adsorption isotherms at 77K. The surface areas of the class F fly ash samples from pulverized coal combustors are between 30-40 m{sup 2}/g, while the samples from the suspension-fired research boiler had surface area around 115 m{sup 2}/g. As expected, the surface areas of the class C ash is much higher than that of the class F ashes, with values up to 390 m{sup 2}/g. In addition, during the current reporting period, also Task 2 ''Development of activated carbons'' and Task 3

  2. Porous texture evolution in Nomex-derived activated carbon fibers.

    PubMed

    Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

    2002-08-01

    In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

  3. A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths

    SciTech Connect

    Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

    1996-05-10

    Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

  4. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion. PMID:21936376

  5. Bacteria associated with granular activated carbon particles in drinking water.

    PubMed Central

    Camper, A K; LeChevallier, M W; Broadaway, S C; McFeters, G A

    1986-01-01

    A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogenization procedure (developed previously) indicated that 41.4% of the water samples had heterotrophic plate count bacteria attached to carbon particles. With the enumeration procedures described, heterotrophic plate count bacteria were recovered at an average rate of 8.6 times higher than by conventional analyses. Over 17% of the samples contained carbon particles colonized with coliform bacteria as enumerated with modified most-probable-number and membrane filter techniques. In some instances coliform recoveries were 122 to 1,194 times higher than by standard procedures. Nearly 28% of the coliforms attached to these particles in drinking water exhibited the fecal biotype. Scanning electron micrographs of carbon fines from treated drinking water showed microcolonies of bacteria on particle surfaces. These data indicate that bacteria attached to carbon fines may be an important mechanism by which microorganisms penetrate treatment barriers and enter potable water supplies. PMID:3767356

  6. Biofuel intercropping effects on soil carbon and microbial activity.

    PubMed

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  7. Treatment of activated carbon to enhance catalytic activity for reduction of nitric oxide with ammonia

    SciTech Connect

    Ku, B.J.; Rhee, H.K. . Dept. of Chemical Engineering); Lee, J.K.; Park, D. )

    1994-11-01

    Catalytic activity of activated carbon treated with various techniques was examined in a fixed bed reactor for the reduction of nitric oxide with ammonia at 150 C. Activated carbon derived from coconut shell impregnated with an aqueous solution of ammonium sulfate, further treated with sulfuric acid, dried at 120 C, and then heated in an inert gas stream at 400 C, showed the highest catalytic activity within the range of experimental conditions. The enhancement of catalytic activity of modified activated carbon could be attributed to the increase in the amount of oxygen function groups which increased the adsorption site for ammonia. Catalytic activity of activated carbons depended on the surface area and the oxygen content as well.

  8. Decolorization of Cheddar cheese whey by activated carbon.

    PubMed

    Zhang, Yue; Campbell, Rachel; Drake, MaryAnne; Zhong, Qixin

    2015-05-01

    Colored Cheddar whey is a source for whey protein recovery and is decolorized conventionally by bleaching, which affects whey protein quality. Two activated carbons were studied in the present work as physical means of removing annatto (norbixin) in Cheddar cheese whey. The color and residual norbixin content of Cheddar whey were reduced by a higher level of activated carbon at a higher temperature between 25 and 55°C and a longer time. Activated carbon applied at 40g/L for 2h at 30°C was more effective than bleaching by 500mg/L of hydrogen peroxide at 68°C. The lowered temperature in activated-carbon treatments had less effect on protein structure as investigated for fluorescence spectroscopy and volatile compounds, particularly oxidation products, based on gas chromatography-mass spectrometry. Activated carbon was also reusable, removing more than 50% norbixin even after 10 times of regeneration, which showed great potential for decolorizing cheese whey. PMID:25704972

  9. Decolorization of Cheddar cheese whey by activated carbon.

    PubMed

    Zhang, Yue; Campbell, Rachel; Drake, MaryAnne; Zhong, Qixin

    2015-05-01

    Colored Cheddar whey is a source for whey protein recovery and is decolorized conventionally by bleaching, which affects whey protein quality. Two activated carbons were studied in the present work as physical means of removing annatto (norbixin) in Cheddar cheese whey. The color and residual norbixin content of Cheddar whey were reduced by a higher level of activated carbon at a higher temperature between 25 and 55°C and a longer time. Activated carbon applied at 40g/L for 2h at 30°C was more effective than bleaching by 500mg/L of hydrogen peroxide at 68°C. The lowered temperature in activated-carbon treatments had less effect on protein structure as investigated for fluorescence spectroscopy and volatile compounds, particularly oxidation products, based on gas chromatography-mass spectrometry. Activated carbon was also reusable, removing more than 50% norbixin even after 10 times of regeneration, which showed great potential for decolorizing cheese whey.

  10. Breakthrough CO₂ adsorption in bio-based activated carbons.

    PubMed

    Shahkarami, Sepideh; Azargohar, Ramin; Dalai, Ajay K; Soltan, Jafar

    2015-08-01

    In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide (KOH) activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25-65°C and inlet CO2 concentration range of 10-30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively. Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm(3)/g and surface area of 1400 m(2)/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after 50 cycles with low temperature (160°C) regeneration.

  11. Phenolic carbon tailored for the removal of polar organic contaminants from water: a solution to the metaldehyde problem?

    PubMed

    Busquets, Rosa; Kozynchenko, Oleksandr P; Whitby, Raymond L D; Tennison, Stephen R; Cundy, Andrew B

    2014-09-15

    Current water treatment technologies are inefficient at treating water contaminated with metaldehyde, an 8-member cyclic tetramer of acetaldehyde widely used as a molluscicide in large-scale agriculture and in gardens, and which has been frequently observed to breach European regulatory limits in the UK due to its high solubility and frequent use. Here, we examine the controls on metaldehyde adsorption onto activated phenolic carbon, namely the influence of activation degree, pore size distribution, particle size, point of zero charge and surface functionalisation, by synthesising "tailored" carbons from phenolic resin. Metaldehyde adsorption has been found to be independent of specific surface area (SBET), which is highly unusual for an adsorption process, and is favoured in carbons with (a) high microporosity with narrow pore size distribution, (b) presence of mesopores which allow efficient diffusive transport, and (c) an absence of negatively charged functional groups. The maximum adsorption capacity of the phenolic resin-derived carbons, tested at an elevated (i.e. exceeding environmental levels) water concentration of 64 mg metaldehyde/L, was 76 mg metaldehyde/g carbon compared with 13 mg metaldehyde/g carbon in industrial granular activated carbon (GAC). The phenolic resin-derived carbons and GAC showed similar adsorption kinetics with maximum metaldehyde uptake occurring within 30 min under batch adsorption conditions, although adsorption isotherms indicate much stronger adsorption of metaldehyde on the phenolic resin-derived carbons. Adsorption efficiency for metaldehyde was maintained even in the presence of high background concentrations of organic matter and inorganic salts, indicating the potential utility of these "designer" carbons in waste and/or drinking water treatment.

  12. Chars pyrolyzed from oil palm wastes for activated carbon preparation

    SciTech Connect

    Lua, A.C.; Guo, J.

    1999-01-01

    Chars pyrolyzed from extracted oil palm fibers for the preparation of activated carbons were studied. The effects of pyrolysis temperature and hold time on density, porosity, yield, BET and micropore surface areas, total pore volume, and pore size distributions of chars were investigated. The optimum conditions for pyrolysis were found to be at a pyrolysis temperature of 850 C for a hold time of 3.5 h. Scanning electron micrographs of the char surfaces verified the presence of porosities. The experimental results showed that it was feasible to produce chars with high BET and micropore surface areas from extracted oil palm fibers. The resulting chars will be subjected to steam or carbon dioxide activation to prepare activated carbons for use as gas adsorbents for air pollution control.

  13. 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.

  14. Improved granular activated carbon for the stabilization of wastewater PH

    SciTech Connect

    Farmer, R.W.; Dussert, B.W.; Kovacic, S.L.

    1996-12-31

    Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.

  15. Posttranscriptional Repression of GacS/GacA-Controlled Genes by the RNA-Binding Protein RsmE Acting Together with RsmA in the Biocontrol Strain Pseudomonas fluorescens CHA0

    PubMed Central

    Reimmann, Cornelia; Valverde, Claudio; Kay, Elisabeth; Haas, Dieter

    2005-01-01

    In the plant-beneficial soil bacterium Pseudomonas fluorescens CHA0, the production of biocontrol factors (antifungal secondary metabolites and exoenzymes) is controlled at a posttranscriptional level by the GacS/GacA signal transduction pathway involving RNA-binding protein RsmA as a key regulatory element. This protein is assumed to bind to the ribosome-binding site of target mRNAs and to block their translation. RsmA-mediated repression is relieved at the end of exponential growth by two GacS/GacA-controlled regulatory RNAs RsmY and RsmZ, which bind and sequester the RsmA protein. A gene (rsmE) encoding a 64-amino-acid RsmA homolog was identified and characterized in strain CHA0. Overexpression of rsmE strongly reduced the expression of target genes (hcnA, for a hydrogen cyanide synthase subunit; aprA, for the main exoprotease; and phlA, for a component of 2,4-diacetylphloroglucinol biosynthesis). Single null mutations in either rsmA or rsmE resulted in a slight increase in the expression of hcnA, aprA, and phlA. By contrast, an rsmA rsmE double mutation led to strongly increased and advanced expression of these target genes and completely suppressed a gacS mutation. Both the RsmE and RsmA levels increased with increasing cell population densities in strain CHA0; however, the amount of RsmA showed less variability during growth. Expression of rsmE was controlled positively by GacA and negatively by RsmA and RsmE. Mobility shift assays demonstrated specific binding of RsmE to RsmY and RsmZ RNAs. The transcription and stability of both regulatory RNAs were strongly reduced in the rsmA rsmE double mutant. In conclusion, RsmA and RsmE together account for maximal repression in the GacS/GacA cascade of strain CHA0. PMID:15601712

  16. [Degradation of orange IV dye solution catalyzed by Fe (NO3)3-(NH4)2S2O8 modified GAC in the presence of H2O2].

    PubMed

    Zhang, Ying-Jie; Xu, Shu-Fen; Liao, Xia; Cao, Tian-Jing; Yang, Rong; Li, Da-Peng

    2012-10-01

    This study was designed to investigate the catalytic oxidation performance of modified GAC by Fe(NO3), and (NH4)2S2O8 in the process of H2O2. The effect of the initial concentration of H2O2, initial dye concentration, catalyst dosage, initial pH and temperature on the reaction was discussed. The results show that the catalyst of Fe/S/GAC has a better catalytic reactivity to decompose Orange IV compared with that of Fe/GAC. The catalyst could decompose H2O2 to degrade Orange IV effectively at pH 2.4-9.1. The removal rate of Orange IV increased with the increase of catalyst dosage. With the decrease of dye concentration, the reaction rate became faster, this reaction followed the second-order reaction kinetics with activation energy (Ea) of 68.19 kJ x mol(-1). Reuse of catalyst did not decrease the removal rate. Orange IV degradation mainly followed OH mechanism.

  17. Carbon-Based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Zhu, Y.; Su, D.; Murali, S.; Stoller, M.D.; Ganesh, K.J.; Cai, W.; Ferreira, P.J.; Pirkle, A.; Wallace, R.M.; Cychosz, K.A., Thommes, M.; Stach, E.A.; Ruoff, R.S.

    2011-06-24

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  18. Carbon-based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Y Zhu; S Murali; M Stoller; K Ganesh; W Cai; P Ferreira; A Pirkle; R Wallace; K Cychosz; et al.

    2011-12-31

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  19. Pore structure of the activated coconut shell charcoal carbon

    NASA Astrophysics Data System (ADS)

    Budi, E.; Nasbey, H.; Yuniarti, B. D. P.; Nurmayatri, Y.; Fahdiana, J.; Budi, A. S.

    2014-09-01

    The development of activated carbon from coconut shell charcoal has been investigated by using physical method to determine the influence of activation parameters in term of temperature, argon gas pressure and time period on the pore structure of the activated carbon. The coconut shell charcoal was produced by pyrolisis process at temperature of about 75 - 150 °C for 6 hours. The charcoal was activated at various temperature (532, 700 and 868 °C), argon gas pressure (6.59, 15 and 23.4 kgf/cm2) and time period of (10, 60 and 120 minutes). The results showed that the pores size were reduced and distributed uniformly as the activation parameters are increased.

  20. Production Scale-Up or Activated Carbons for Ultracapacitors

    SciTech Connect

    Dr. Steven D. Dietz

    2007-01-10

    Transportation use accounts for 67% of the petroleum consumption in the US. Electric and hybrid vehicles are promising technologies for decreasing our dependence on petroleum, and this is the objective of the FreedomCAR & Vehicle Technologies Program. Inexpensive and efficient energy storage devices are needed for electric and hybrid vehicle to be economically viable, and ultracapacitors are a leading energy storage technology being investigated by the FreedomCAR program. The most important parameter in determining the power and energy density of a carbon-based ultracapacitor is the amount of surface area accessible to the electrolyte, which is primarily determined by the pore size distribution. The major problems with current carbons are that their pore size distribution is not optimized for liquid electrolytes and the best carbons are very expensive. TDA Research, Inc. (TDA) has developed methods to prepare porous carbons with tunable pore size distributions from inexpensive carbohydrate based precursors. The use of low-cost feedstocks and processing steps greatly lowers the production costs. During this project with the assistance of Maxwell Technologies, we found that an impurity was limiting the performance of our carbon and the major impurity found was sulfur. A new carbon with low sulfur content was made and found that the performance of the carbon was greatly improved. We also scaled-up the process to pre-production levels and we are currently able to produce 0.25 tons/year of activated carbon. We could easily double this amount by purchasing a second rotary kiln. More importantly, we are working with MeadWestvaco on a Joint Development Agreement to scale-up the process to produce hundreds of tons of high quality, inexpensive carbon per year based on our processes.

  1. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  2. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon.

  3. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon. PMID:25881437

  4. Synthesis and characterization of activated carbon from asphalt

    NASA Astrophysics Data System (ADS)

    Kandah, Munther Issa; Shawabkeh, Reyad; Al-Zboon, Mahmoud Ar'ef

    2006-11-01

    Asphalt (cheap and available in huge amount in Jordan) was converted into activated carbon powder by chemical treatment with sulphuric and nitric acids at 450 °C. The final product was characterized and found effective as adsorbent material. Its cation exchange capacity reaches 191.2 meq/100-g carbons when treated with 30 wt% acid/asphalt ratio without airflow rate injection and 208 meq/100-g carbons when 6.5 ml air/min was injected into the surface of the asphalt during activation at the same acid/asphalt weight ratio of 30 and temperature 450 °C. The zero point of charge for this product was found to be stable at pH value around 3 in the range of initial pH between 3 and 10.

  5. Activity of catalase adsorbed to carbon nanotubes: effects of carbon nanotube surface properties.

    PubMed

    Zhang, Chengdong; Luo, Shuiming; Chen, Wei

    2013-09-15

    Nanomaterials have been studied widely as the supporting materials for enzyme immobilization. However, the interactions between enzymes and carbon nanotubes (CNT) with different morphologies and surface functionalities may vary, hence influencing activities of the immobilized enzyme. To date how the adsorption mechanisms affect the activities of immobilized enzyme is not well understood. In this study the adsorption of catalase (CAT) on pristine single-walled carbon nanotubes (SWNT), oxidized single-walled carbon nanotubes (O-SWNT), and multi-walled carbon nanotubes (MWNT) was investigated. The adsorbed enzyme activities decreased in the order of O-SWNT>SWNT>MWNT. Fourier transforms infrared spectroscopy (FTIR) and circular dichrois (CD) analyses reveal more significant loss of α-helix and β-sheet of MWNT-adsorbed than SWNT-adsorbed CAT. The difference in enzyme activities between MWNT-adsorbed and SWNT-adsorbed CAT indicates that the curvature of surface plays an important role in the activity of immobilized enzyme. Interestingly, an increase of β-sheet content was observed for CAT adsorbed to O-SWNT. This is likely because as opposed to SWNT and MWNT, O-SWNT binds CAT largely via hydrogen bonding and such interaction allows the CAT molecule to maintain the rigidity of enzyme structure and thus the biological function.

  6. Graphene-analogue carbon nitride: novel exfoliation synthesis and its application in photocatalysis and photoelectrochemical selective detection of trace amount of Cu2+

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Yan, Jia; She, Xiaojie; Xu, Li; Xia, Jiexiang; Xu, Yuanguo; Song, Yanhua; Huang, Liying; Li, Huaming

    2014-01-01

    Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene-analogue carbon nitride had a new features that could make it suitable as a sensor for Cu2+ determination. So GA-C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu2+ were also discussed.Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene

  7. Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

    PubMed

    Jalilov, Almaz S; Ruan, Gedeng; Hwang, Chih-Chau; Schipper, Desmond E; Tour, Josiah J; Li, Yilun; Fei, Huilong; Samuel, Errol L G; Tour, James M

    2015-01-21

    Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600 °C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m(2) g(-1) and high CO2 uptake performance of 21 mmol g(-1) or 93 wt % at 30 bar and 25 °C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m(2) g(-1) for A-NPC and CO2 uptake to 26 mmol g(-1) or 114 wt % at 30 bar and 25 °C for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO2 is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive.

  8. 40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 60.1820 Section 60.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  9. Black carbon-mediated reduction of 2,4-dinitrotoluene by dithiothreitol.

    PubMed

    Oh, Seok-Young; Son, Jong-Gil; Hur, Seung Hyun; Chung, Jin Suk; Chiu, Pei C

    2013-01-01

    By using various types of black carbon (BC), including chemically converted graphene (CCG), multiwalled carbon nanotubes (MWCNT), and granular activated carbon (GAC), BC-mediated reduction was investigated with 2,4-dinitrotoluene (DNT), a model nitroaromatic compound. We hypothesized that by providing sorption and electron transfer sites, BC can be used as a catalyst to accelerate DNT reduction by dithiothreitol (DTL), a thiol reductant. Results from batch experiments showed that CCG, MWCNT, and GAC could promote reduction of DNT by DTL. The yield ratio of the two aminonitro intermediates was approximately 1:1, which was consistent with that in a graphite system. However, fullerene did not significantly enhance the reduction of DNT, likely due to being a π acceptor. Kinetic data analysis showed that removal of DNT in the presence of BC and DTL was linearly proportional to the electrical conductivity of BC, suggesting that the graphitic structure of BC may be responsible for DNT removal. Our results indicate that the presence of BC materials may affect the fate of nitroaromatic compounds under electron-rich conditions.

  10. Black carbon-mediated reduction of 2,4-dinitrotoluene by dithiothreitol.

    PubMed

    Oh, Seok-Young; Son, Jong-Gil; Hur, Seung Hyun; Chung, Jin Suk; Chiu, Pei C

    2013-01-01

    By using various types of black carbon (BC), including chemically converted graphene (CCG), multiwalled carbon nanotubes (MWCNT), and granular activated carbon (GAC), BC-mediated reduction was investigated with 2,4-dinitrotoluene (DNT), a model nitroaromatic compound. We hypothesized that by providing sorption and electron transfer sites, BC can be used as a catalyst to accelerate DNT reduction by dithiothreitol (DTL), a thiol reductant. Results from batch experiments showed that CCG, MWCNT, and GAC could promote reduction of DNT by DTL. The yield ratio of the two aminonitro intermediates was approximately 1:1, which was consistent with that in a graphite system. However, fullerene did not significantly enhance the reduction of DNT, likely due to being a π acceptor. Kinetic data analysis showed that removal of DNT in the presence of BC and DTL was linearly proportional to the electrical conductivity of BC, suggesting that the graphitic structure of BC may be responsible for DNT removal. Our results indicate that the presence of BC materials may affect the fate of nitroaromatic compounds under electron-rich conditions. PMID:23673948

  11. Overview of EPA activities and research related to black carbon

    EPA Science Inventory

    The purpose of this international presentation is to give an overview of EPA activities related to black carbon (BC). This overview includes some summary information on how EPA defines BC, current knowledge on United States emissions and forecasted emission reductions, and ongoin...

  12. Preparation and characterization of activated carbon from demineralized tyre char

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Prasad, Guddu R.; Joshi, Parth.; Zala, Ranjitsingh S.; Gokhale, Siddharth S.; Manocha, L. M.

    2013-06-01

    Activated carbon is the most adsorbing material for industrial waste water treatment. For wider applications, the main consideration is to manufacture activated carbon from low cost precursors, which are easily available and cost effective. One such source is scrap tyres. Recently much effort has been devoted to the thermal degradation of tyres into gaseous and liquid hydrocarbons and solid char residue, all of which have the potential to be processed into valuable products. As for solid residue, char can be used either as low-grade reinforcing filler or as activated carbon. The product recovered by a typical pyrolysis of tyres are usually, 33-38 wt% pyrolytic char, 38-55 wt% oil and 10-30 wt% solid fractions. In the present work activated carbon was prepared from pyrolyzed tyre char (PC). Demineralization involves the dissolution of metal into acids i.e. HCl, HNO3 and H2SO4 and in base i.e. NaOH. Different concentration of acid and base were used. Sodium hydroxide showed maximum amount of metal oxide removal. Further the concentration of sodium hydroxide was varied from 1N to 6N. As the concentration of acid are increased demineralization increases. 6N Sodium hydroxide is found to be more effective demineralising agent of tyre char.

  13. Activated carbon injection - a mercury control success story

    SciTech Connect

    2008-07-01

    Almost 100 full-scale activated carbon injection (ACI) systems have been ordered by US electric utilities. These systems have the potential to remove over 90% of the mercury in flue, at a cost below $10,000 per pound of mercury removal. Field trials of ACI systems arm outlined. 1 fig.

  14. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An activated carbon fiber nonwoven (ACF) was manufactured from cotton nonowoven fabric. For the ACF acoustical application, a nonwoven composite of ACF with cotton nonwoven as a base layer was developed. Also produced were the composites of the cotton nonwoven base layer with a layer of glass fiber ...

  15. Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue.

    PubMed

    Zhang, Xianlong; Cheng, Liping; Wu, Xueping; Tang, Yingzhao; Wu, Yucheng

    2015-07-01

    An activation process for developing the surface and porous structure of palygorskite/carbon (PG/C) nanocomposite using ZnCl2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM), and Brunauer-Emmett-Teller analysis (BET) techniques. The effects of activation conditions were examined, including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of CC and C-H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold (1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay. PMID:26141882

  16. Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue.

    PubMed

    Zhang, Xianlong; Cheng, Liping; Wu, Xueping; Tang, Yingzhao; Wu, Yucheng

    2015-07-01

    An activation process for developing the surface and porous structure of palygorskite/carbon (PG/C) nanocomposite using ZnCl2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM), and Brunauer-Emmett-Teller analysis (BET) techniques. The effects of activation conditions were examined, including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of CC and C-H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold (1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay.

  17. Activation and micropore structure of carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-12-01

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The main focus of recent work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites to produce controlled pore structures. Processes have been developed using activation in steam and CO{sub 2}, and a less conventional method involving oxygen chemisorption and subsequent heat treatment. Another objective has been to explore applications for the activated composites in environmental applications related to fossil energy production.

  18. Petroleum pollutants in surface and groundwater as indicated by the carbon-14 activity of dissolved organic carbon.

    PubMed

    Spiker, E C; Rubin, M

    1975-01-10

    The (14)C activity of dissolved organic carbon (DOC) can be used to distinguish between the fossil organic carbon due to petrochemical effluents