Sample records for anaerobic digester gas

  1. FCPP application to utilize anaerobic digester gas

    SciTech Connect

    Nakayama, Yoshio; Kusama, Nobuyuki; Wada, Katsuya [Toshiba Corp., Tokyo (Japan)

    1996-12-31

    Toshiba and a municipal organization of Yokohama city are jointly conducting a program to utilize ADG (Anaerobic Digester Gas) more effectively. ADG which contains about 60% methane is produced by anaerobic digestion of waste water treatment sludge and has been used as an energy source for heating digestion tanks in sewage treatment plants and/or for combustion engine fuel. This program is focused on operating a commercial Phosphoric Acid Fuel Cell (PAFC) power plant on ADG because of its inherently high fuel efficiency and low emissions characteristics. According to the following joint program, we have successfully demonstrated an ADG fueled FCPP The success of this study promises that the ADG fueled FCPP, an environment-friendly power generation system, will be added to the line-up of PC25{trademark}C applications.

  2. Test results for fuel cell operation on anaerobic digester gas

    NASA Astrophysics Data System (ADS)

    Spiegel, R. J.; Preston, J. L.

    EPA, in conjunction with ONSI, embarked on a project to define, design, test, and assess a fuel cell energy recovery system for application at anaerobic digester waste water (sewage) treatment plants. Anaerobic digester gas (ADG) is produced at these plants during the process of treating sewage anaerobically to reduce solids. ADG is primarily comprised of methane (57-66%), carbon dioxide (33-39%), nitrogen (1-10%), and a small amount of oxygen (<0.5%). Additionally, ADG contains trace amounts of fuel cell catalyst contaminants consisting of sulfur-bearing compounds (principally hydrogen sulfide) and halogen compounds (chlorides). The project has addressed two major issues: development of a cleanup system to remove fuel cell contaminants from the gas and testing/assessing of a modified ONSI PC25 C fuel cell power plant operating on the cleaned, but dilute, ADG. Results to date demonstrate that the ADG fuel cell power plant can, depending on the energy content of the gas, produce electrical output levels close to full power (200 kW) with measured air emissions comparable to those obtained by a natural gas fuel cell. The cleanup system results show that the hydrogen sulfide levels are reduced to below 10 ppbv and halides to approximately 30 ppbv.

  3. Membrane controlled anaerobic digestion

    NASA Astrophysics Data System (ADS)

    Omstead, D. R.

    In response to general shortages of energy, examination of the anaerboic digestion process as a potential source of a combustible, methane-rich fuel has intensified in recent years. It has been suggested that orgaic intermediates (such as fatty acids), produced during digestion, might also be recovered for use as chemical feedstocks. This investigation has been concerned with combining ultrafiltration separation techniques with anaerobic digestion for the development of a process in which the total production of acetic acid (the most valuable intermediate in anaerobic digestion) and methane are optimized. Enrichment cultures, able to utilize glucose as a sole carbon source, were adapted from sewage digesting cultures using conventional techniques. An ultrafiltration system was constructed and coupled to an anaerobic digester culture vessel which contained the glucose enrichment. The membrane controlled anaerobic digester appears to show promise as a means of producing high rates of both methane gas and acetic acid.

  4. FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS: CONCEPTUAL DESIGN AND ASSESSMENT

    EPA Science Inventory

    The conceptual design of a fuel cell (FC) system for operation on anaerobic digester gas (ADG) is described and its economic and environmental feasibility is projected. ADG is produced at water treatment plants during the process of treating sewage anaerobically to reduce solids....

  5. Economic viability of anaerobic digestion

    SciTech Connect

    Wellinger, A. [INFOENERGIE, Ettenhausen (Switzerland)

    1996-01-01

    The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters - type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates - define the investment and operating costs of an anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters is somewhat higher than that of anaerobic digestion, but the investment costs 1 1/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.

  6. Economic viability of anaerobic digestion

    SciTech Connect

    Wellinger, A. [INFOENERGIE, Ettenhausen (Switzerland)

    1995-11-01

    The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters-type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates-define the investment and operating costs of anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters in somewhat higher than that of anaerobic digestion, but the investment costs 11/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.

  7. Using anhydrous ammonia during anaerobic digester startup

    SciTech Connect

    Trout, P.A. (HDR Engineering, Inc., Omaha, NE (United States)); Schultz, T.; Schlegel, G.K.

    1991-09-01

    During a new wastewater treatment plant (WTP) startup, several systems cannot be placed in full operation or fine tuned until the anaerobic digestion system is fully on-line, stable, and producing sufficient quantities of burnable gas. To start up and demonstrate these systems while reducing plant utility costs, the anaerobic digester startup must proceed smoothly and the time between beginning digester sludge feed and achieving stable operation must be as short as possible. Controlling anaerobic digester pH and neutralizing volatile fatty acids are commonly required during anaerobic digester startup. This is especially true when good quality seed sludge is not available from operating digesters. If seed sludge is not available, planning for and implementing alkaline chemical feed to the digesters is necessary. Anhydrous ammonia can also be used to control anaerobic digester pH and increase digester buffering capacity.

  8. Solar heated anaerobic digester

    Microsoft Academic Search

    Rhoades

    1980-01-01

    The title digester is adapted to utilize organic waste material capable of decomposing to produce CHâ and a liquid fertilizer. The sealed anaerobic digester is wrapped with a layer of heat-absorptive material followed by a series of abutting removable panels of insulative material. Insulative panels may be temporarily removed to expose the heat-absorptive material to solar radiation and may be

  9. Fuel cell operation on anaerobic digester gas: Conceptual design and assessment

    SciTech Connect

    Spiegel, R.J.; Thorneloe, S.A. (Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Lab.); Trocciola, J.C.; Preston, J.L. (ONSI Corp., South Windsor, CT (United States))

    1999-01-01

    The conceptual design of a fuel cell (FC) system for operation on anaerobic digester gas (ADG) is described and its economic and environmental feasibility is projected. ADG is produced at wastewater treatment plants during the process of treating sewage anaerobically to reduce solids. The economic feasibility study shows the fuel cell is economical where plant electricity costs are 5 [cents]/kW h or higher, based on entry level fuel cell costs of $3,000/kW. FCs are one of the cleanest energy technologies available, and the widespread use of this concept should result in a significant reduction in global warming gas and acid rain air emissions. Additionally, technology evaluation focused on improving a commercial phosphoric acid FC power plant operation on ADG is described.

  10. Fuel cell operation on anaerobic digester gas: Conceptual design and assessment

    SciTech Connect

    Spiegel, R.J.; Thorneloe, S.A. [Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Lab.] [Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Lab.; Trocciola, J.C.; Preston, J.L. [ONSI Corp., South Windsor, CT (United States)] [ONSI Corp., South Windsor, CT (United States)

    1999-11-01

    The conceptual design of a fuel cell (FC) system for operation on anaerobic digester gas (ADG) is described and its economic and environmental feasibility is projected. ADG is produced at wastewater treatment plants during the process of treating sewage anaerobically to reduce solids. The economic feasibility study shows the fuel cell is economical where plant electricity costs are 5 [cents]/kW h or higher, based on entry level fuel cell costs of $3,000/kW. FCs are one of the cleanest energy technologies available, and the widespread use of this concept should result in a significant reduction in global warming gas and acid rain air emissions. Additionally, technology evaluation focused on improving a commercial phosphoric acid FC power plant operation on ADG is described.

  11. The Anaerobic Digestion of Organic

    E-print Network

    Iglesia, Enrique

    The Anaerobic Digestion of Organic Municipal Solid Waste in California. Anaerobic Digestion Technology 2.1. Feedstock Characterization 2.2. Collection & Sorting 2.2.1. Waste of Anaerobic Digestion 3.1. Municipal Waste Management 3.2. Climate Change Mitigation 3.2.1. Untreated

  12. Solar heated anaerobic digester

    SciTech Connect

    Rhoades, D.

    1980-09-09

    The title digester is adapted to utilize organic waste material capable of decomposing to produce CH/sub 4/ and a liquid fertilizer. The sealed anaerobic digester is wrapped with a layer of heat-absorptive material followed by a series of abutting removable panels of insulative material. Insulative panels may be temporarily removed to expose the heat-absorptive material to solar radiation and may be replaced when the solar radiation diminishes. A layer of transparent material wrapped in outwardly spaced relation around the insulating panels is capable of transmitting solar radiation while providing protection against environmental elements. Additional heating means extending into the digester provide auxiliary heat as required.

  13. The anaerobic digestion process

    SciTech Connect

    Rivard, C.J. [National Renewable Energy Lab., Golden, CO (United States); Boone, D.R. [Oregon Graduate Inst., Portland, OR (United States)

    1996-01-01

    The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.

  14. Technical assessment of fuel cell operation on anaerobic digester gas at the Yonkers, NY, wastewater treatment plant

    Microsoft Academic Search

    R. J. Spiegel; J. L. Preston

    2003-01-01

    This paper summarizes the results of a 2-year field test to assess the performance of a specially modified commercial phosphoric acid 200-kW fuel cell power plant to recover energy from anaerobic digester gas (ADG) which has been cleansed of contaminants (sulfur and halide compounds) using a patented gas pretreatment unit (GPU). Specific project goals include characterization of the fuel cell

  15. Modeling anaerobic digestion

    SciTech Connect

    Li, Yanlong.

    1988-01-01

    A computer model was developed for a completely-mixed swine-manure digester operated at 35 C. It satisfactorily predicted polymer degradation, gas production, VFA concentration, and VS reduction at steady state. It accurately predicted digester instability under conditions of shock loading, changing HRT, and step loading. The model was also able to predict polymer degradation in a batch culture. Inhibitory effects of VFA, ammonia, and hydrogen were investigated. VFA and ammonia did not necessarily cause digester failure directly. However, at high concentrations, they resulted in an increase in hydrogen concentration. The increase in hydrogen concentration, in turn, caused digester instability and eventually digester failure. The feedback inhibition of hydrogen on acidogens was crucial in the instability process. Influence of LR and HRT on the digestion process were evaluated in the region where experimental data were not available. Better digester performance were achieved by increasing LR or HRT until a significantly high LR or HRT caused digester failure.

  16. Anaerobic digestion of ozonized biosolids

    Microsoft Academic Search

    M Weemaes; H Grootaerd; F Simoens; W Verstraete

    2000-01-01

    The effect of an oxidative pretreatment on the anaerobic digestion of sewage sludge was investigated. Sewage sludge from a domestic wastewater treatment plant was partially oxidized by ozone. The pretreatment could alter up to 67% of the organic matter: 29±3% was solubilized, 38±9% was removed. Anaerobic degradability tests indicated that the pretreatment step enhanced the subsequent anaerobic sludge digestion. The

  17. TECHNICAL ASSESSMENT OF FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS AT THE YONKERS, NY, WASTEWATER TREATMENT PLANT

    EPA Science Inventory

    The paper summarizes the results of a 2-year field test to assess the performance of a specially modified commercial phosphoric acid 200 kW fuel cell power plant to recover energy from anaerobic digester gas (ADG) which has been cleansed of contaminants (sulfur and halide compoun...

  18. The anaerobic digestion of organic solid wastes

    SciTech Connect

    Hartung, H.A. [Hartung (H.A.), Collingswood, NJ (United States)

    1996-09-01

    Anaerobic digestion offers many advantages in the processing of organic solid wastes, using a closed system to convert the waste to combustible gas and a stabilized organic residue.Odors are contained while digestion removes their source and gas is collected for energy recovery as heat or electricity. The stabilized residue is less than the starting waste by the mass of gas produced, and it can be disposed of by land application, land filling, incineration or composting. The stimulation of digesters and the phenomenon of co-digestion are two ways the performance of anaerobic digesters can be enhanced. Data from farm digesters and municipal wastewater treatment plants illustrate the present venue of the process; laboratory studies of the anaerobic digestion of a variety of solid wastes show that the process can be applied to these materials as well. About two thirds of municipal solid waste is shown to be amenable to anaerobic digestion in a substrate from an active municipal sewage plant digester.

  19. Apparatus for the anaerobic digestion of natural organic waste

    SciTech Connect

    Hawkes, D.L.; Horton, R.; Stafford, D.A.

    1980-11-11

    The title system consists of a feed tank, from which sewage is provided to a digester tank at an adjustable continuous weight, in which the sewage is anaerobically digested. The gas produced in the anaerobic digester is collected at the top and pumped to a diffuser at the bottom of the digester. The supernatent from the treated sewage is transferred to an outlet tank, and sludge is removed from the bottom of the digester tank.

  20. Anaerobic Digestion of Biowaste in Developing Countries

    E-print Network

    Wehrli, Bernhard

    Anaerobic Digestion of Biowaste in Developing Countries Practical Information and Case Studies Sandec: Department of Water and Sanitation in Developing Countries #12;Anaerobic Digestion of Biowaste-3-906484-58-7 Bibliographic reference: Vögeli Y., Lohri C. R., Gallardo A., Diener S., Zurbrügg C. (2014). Anaerobic Digestion

  1. Anaerobic Digestion of Primary Sewage Effluent

    E-print Network

    Anaerobic Digestion of Primary Sewage Effluent: Significant Energy Savings over Traditional Activated Sludge Treatment This report presents results for an anaerobic digestion system operated;Anaerobic Digestion of Primary Sewage Effluent Prepared for the U.S. Department of Energy Office

  2. Inhibition of anaerobic digestion process: A review

    Microsoft Academic Search

    Ye Chen; Jay J. Cheng; Kurt S. Creamer

    2008-01-01

    Anaerobic digestion is an attractive waste treatment practice in which both pollution control and energy recovery can be achieved. Many agricultural and industrial wastes are ideal candidates for anaerobic digestion because they contain high levels of easily biodegradable materials. Problems such as low methane yield and process instability are often encountered in anaerobic digestion, preventing this technique from being widely

  3. Biochar from anaerobically digested sugarcane bagasse

    Microsoft Academic Search

    Mandu Inyang; Bin Gao; Pratap Pullammanappallil; Wenchuan Ding; Andrew R. Zimmerman

    2010-01-01

    This study was designed to investigate the effect of anaerobic digestion on biochar produced from sugarcane bagasse. Sugarcane bagasse was anaerobically digested to produce methane. The digested residue and fresh bagasse was pyrolyzed separately into biochar at 600°C in nitrogen environment. The digested bagasse biochar (DBC) and undigested bagasse biochar (BC) were characterized to determine their physicochemical properties. Although biochar

  4. [Anaerobic digestion of lignocellulosic biomass with animal digestion mechanisms].

    PubMed

    Wu, Hao; Zhang, Pan-Yue; Guo, Jian-Bin; Wu, Yong-Jie

    2013-02-01

    Lignocellulosic material is the most abundant renewable resource in the earth. Herbivores and wood-eating insects are highly effective in the digestion of plant cellulose, while anaerobic digestion process simulating animal alimentary tract still remains inefficient. The digestion mechanisms of herbivores and wood-eating insects and the development of anaerobic digestion processes of lignocellulose were reviewed for better understanding of animal digestion mechanisms and their application in design and operation of the anaerobic digestion reactor. Highly effective digestion of lignocellulosic materials in animal digestive system results from the synergistic effect of various digestive enzymes and a series of physical and biochemical reactions. Microbial fermentation system is strongly supported by powerful pretreatment, such as rumination of ruminants, cellulase catalysis and alkali treatment in digestive tract of wood-eating insects. Oxygen concentration gradient along the digestive tract may stimulate the hydrolytic activity of some microorganisms. In addition, the excellent arrangement of solid retention time, digesta flow and end product discharge enhance the animal digestion of wood cellulose. Although anaerobic digestion processes inoculated with rumen microorganisms based rumen digestion mechanisms were developed to treat lignocellulose, the fermentation was more greatly limited by the environmental conditions in the anaerobic digestion reactors than that in rumen or hindgut. Therefore, the anaerobic digestion processes simulating animal digestion mechanisms can effectively enhance the degradation of wood cellulose and other organic solid wastes. PMID:23668159

  5. Anaerobic digestion of space mission wastes.

    PubMed

    Chynoweth, D P; Owens, J M; Teixeira, A A; Pullammanappallil, P; Luniya, S S

    2006-01-01

    The technical feasibility of applying leachbed high-solids anaerobic digestion for reduction and stabilization of the organic fraction of solid wastes generated during space missions was investigated. This process has the advantages of not requiring oxygen or high temperature and pressure while producing methane, carbon dioxide, nutrients, and compost as valuable products. Anaerobic biochemical methane potential assays run on several waste feedstocks expected during space missions resulted in ultimate methane yields ranging from 0.23 to 0.30 L g-1 VS added. Modifications for operation of a leachbed anaerobic digestion process in space environments were incorporated into a new design, which included; (1) flooded operation to force leachate through densified feedstock beds; and (2) separation of biogas from leachate in a gas collection reservoir. This mode of operation resulted in stable performance with 85% conversion of a typical space solid waste blend, and a methane yield of 0.3 Lg per g VS added after a retention time of 15 days. These results were reproduced in a full-scale prototype system. A detailed analysis of this process was conducted to design the system sized for a space mission with a six-person crew. Anaerobic digestion compared favorably with other technologies for solid waste stabilization. PMID:16784202

  6. Anaerobic digestion of olive mill wastewaters

    Microsoft Academic Search

    M. Hamdi; K. Stamatelatou; M. Kornaros; G. Lyberatos

    1996-01-01

    Anaerobic digestions for the treatment of olive mill wastewaters (OMW) are reviewed. A major limitation of anaerobic digestion of OMW is inhibition of methanogenic bacteria by simple phenolic compounds, certain organic acids and polyphenols. Pretreatment methods that modify or remove these natural inhibitors improve digestion of OMW.

  7. Cultivation of marine microalgae using shale gas flowback water and anaerobic digestion effluent as the cultivation medium.

    PubMed

    Racharaks, Ratanachat; Ge, Xumeng; Li, Yebo

    2015-09-01

    The potential of shale gas flowback water and anaerobic digestion (AD) effluent to reduce the water and nutrient requirements for marine microalgae cultivation was evaluated with the following strains: Nannochloropsis salina, Dunaliella tertiolecta, and Dunaliella salina. N. salina and D. tertiolecta achieved the highest biomass productivity in the medium composed of flowback water and AD effluent (6% v/v). Growth in the above unsterilized medium was found to be comparable to that in sterilized commercial media with similar initial inorganic nitrogen concentrations, salinity, and pH levels. Specific growth rates of 0.293 and 0.349day(-1) and average biomass productivities of 225 and 275mgL(-1)day(-1) were obtained for N. salina and D. tertiolecta, respectively. The lipid content and fatty acid profile of both strains in the medium were also comparable to those obtained with commercial nutrients and salts. PMID:25989090

  8. Anaerobic sludge digestion with a biocatalytic additive

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Fedde, P.A.

    1982-01-01

    The objective of this research was to evaluate the effects of a lactobacillus additive an anaerobic sludge digestion under normal, variable, and overload operating conditions. The additive was a whey fermentation product of an acid-tolerant strain of Lactobacillus acidophilus fortified with CaCO/sub 3/, (NH/sub 4/)/sub 2/HPO/sub 4/, ferrous lactate, and lactic acid. The lactobacillus additive is multifunctional in nature and provides growth factors, metabolic intermediates, and enzymes needed for substrate degradation and cellular synthesis. The experimental work consisted of several pairs of parallel mesophilic (35/sup 0/C) digestion runs (control and test) conducted in five experimental phases. Baseline runs without the additive showed that the two experimental digesters had the same methane content, gas production rate (GPR), and ethane yield. The effect of the additive was to increase methane yield and GPR by about 5% (which was statistically significant) during digester operation at a loading rate (LR) of 3.2 kg VS/m/sup 3/-day and a hydraulic retention time (HRT) of 14 days. Data collected from the various experimental phases showed that the biochemical additive increased methane yield, gas production rate, and VS reduction, and decreased volatile acids accumulation. In addition, it enhanced digester buffer capacity and improved the fertilizer value and dewatering characteristics of the digested residue.

  9. Hemicellulose conversion by anaerobic digestion

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Christopher, R.W.

    1982-01-01

    The digestibility of an aquatic biomass (water hyacinth), a land-based biomass (Coastal Bermuda grass), and a biomass-waste blend (a mixture of hyacinth, grass, MSW, and sludge) under various digestion conditions was studied. Anaerobic digestion of hemicellulose consists of the steps of enzymatic hydrolysis of hemicellulose to glucans, mannans, galactans, xylans, and arabans, and then to simple hexose and pentose sugars; production of C/sub 2/ and higher fatty acids from the simple sugars; conversion of higher fatty acids to acetate; and finally, production of methane and CO/sub 2/ from acetate, and CO/sub 2/ and hydrogen. The conversion of hemicellulose was higher under mesophilic conditions than those of cellulose or protein for all biomass test feeds, probably because the hemicellulose structure was more vulnerable to enzymatic attack than that of the lignocellulosic component. Cellulose conversion efficiencies at the mesophilic and thermophilic temperatures were about the same. However, hemicellulose was converted at a much lower efficiency than cellulose during thermophilic digestion - a situation that was the reverse of that observed at the mesophilic temperature. Cellulose was utilized in preference to hemicellulose during mesophilic digestion of nitrogen-supplemented Bermuda grass. It was speculated that Bermuda grass cellulose was converted at a higher efficiency than hemicellulose in the presence of external nitrogen because the metabolism of the breakdown product (glucose) of cellulose requires the least investment of enzymes and energy.

  10. Control of interspecies electron transfer flow during anaerobic digestion: dynamic diffusion reaction models for hydrogen gas transfer in microbial flocs.

    PubMed

    Ozturk, S S; Palsson, B O; Thiele, J H

    1989-02-01

    Dynamic reaction diffusion models were used to analyze the consequences of aggregation for syntrophic reactions in methanogenic ecosystems. Flocs from a whey digestor were used to measure all model parameters under the in situ conditions of a particular defined biological system. Fermentation simulations without adjustable parameters could precisely predict the kinetics of H(2) gas production of digestor flocs during syntrophic methanogenesis from ethanol. The results demonstrated a kinetic compartmentalization of H(2) metabolism inside the flocs. The interspecies electron transfer reaction was mildly diffusion controlled. The H(2) gas profiles across the flocs showed high H (2) concentrations inside the flocs at any time. Simulations of the syntrophic metabolism at low substrate concentrations such as in digestors or sediments showed that it is impossible to achieve high H(2) gas turnovers at simultaneously low steady-state H(2) concentrations. This showed a mechanistic contradiction in the concept of postulated low H(2) microenvironments for the anaerobic digestion process. The results of the computer experiments support the conclusion that syntrophic H(2) production may only be a side reaction of H(2) independent interspecies electron transfer in methanogenic ecosystems. PMID:18587976

  11. Anaerobic digestion of municipal solid waste

    Microsoft Academic Search

    Michael K. Stenstrom; Adam S. Ng; Prasanta K. Bhunia; Seth D. Abramson

    1983-01-01

    Anaerobic digestion of classified municipal solid waste is a proposed disposal method for the mushrooming quantities of solid waste. To determine the suitability of anaerobic digestion to Los Angeles area wastes, a two-year pilot-scale study was conducted. A survey of a Southern California community was made to determine typical municipal waste composition. Municipal solid waste with characteristics conforming to survey

  12. SERI Anaerobic Digestion Program. 1984 annual report

    Microsoft Academic Search

    Lowenstein

    1985-01-01

    This report summarizes the progress and research accomplishments of the DOE Anaerobic Digestion Program. The objective is to develop the technology base for anaerobic digestion of dedicated feedstocks to produce significant quantities of methane at a cost competitive with other gaseous fuels by 1995. During 1984 research was carried out under three tasks: pretreatment, biological processes, and engineering parameters. Pretreatment

  13. DEMONSTRATION OF FUEL CELLS TO RECOVER ENERGY FROM ANAEROBIC DIGESTER GAS - PHASE I. CONCEPTUAL DESIGN, PRELIMINARY COST, AND EVALUATION STUDY

    EPA Science Inventory

    The report discusses Phase I (a conceptual design, preliminary cost, and evaluation study) of a program to demonstrate the recovery of energy from waste methane produced by anaerobic digestion of waste water treatment sludge. The fuel cell is being used for this application becau...

  14. Evaluating anaerobic digestion for reduction of organic wastes

    SciTech Connect

    Hartung, H.A. [Hartung (H.A.), Collingswood, NJ (United States)

    1994-12-31

    A small-scale anaerobic digestion test has been developed for monitoring start-up work with inoperative digesters. The test is described and variables critical to its consistent operation are detailed. The method has been used in many anaerobic digestion studies, including evaluation of the digestibility of various municipal solid wastes like grass and hedge clippings, garbage and newspapers. Digestion rates are expressed in terms of the rate of production of combustible gas and the retention time needed for a fixed degree of volatile solids destruction. An example shows the advantage of digesting selected combined charges, and it is suggested that this approach might be fruitful with many toxic organic materials. Application of this test to find the digestion rates of some high-yield biomass crops is also described.

  15. Production of clean energy by anaerobic digestion of phytomass—New prospects for a global warming amelioration technology

    Microsoft Academic Search

    Tasneem Abbasi; S. A. Abbasi

    2010-01-01

    Anaerobic digestion of animal dung generated combustible gas – this fact has been known since over 130 years and has been gainfully utilized in generating clean energy in the form of methane-rich ‘biogas’. During 1970s it was found that aquatic weeds and other phytomass, if anaerobically digested, also produced similarly combustible ‘bio’ gas. It raised great hopes that anaerobic digestion

  16. On-farm anaerobic digester and fuel alcohol plant

    SciTech Connect

    Not Available

    1985-01-01

    An anaerobic digestion system was constructed and set up on a southern Illinois farm. The anaerobic digestion system was designed to be coupled with a fuel alcohol plant constructed by the farm family as part of an integrated farm energy system. The digester heating can be done using waste hot water from the alcohol plant and biogas from the digester can be used as fuel for the alcohol production. The anaerobic digestion system is made up of the following components. A hog finishing house, which already had a slotted floor and manure pit beneath it, was fitted with a system to scrape the manure into a feed slurry pit constructed at one end of the hog house. A solids handling pump feeds the manure from the feed slurry pit into the digester, a 13,000 gallon tank car body which has been insulated with styrofoam and buried underground. Another pump transfers effluent (digested manure) from the digester to a 150,000 gallon storage tank. The digested manure is then applied to cropland at appropriate times of the year. The digester temperature is maintained at the required level by automated hot water circulation through an internal heat exchanger. The biogas produced in the digester is pumped into a 32,000 gallon gas storage tank.

  17. FERTILITY AND TOXICITY OF POTTING SOILS PREPARED FOR GINNING AND DAIRY WASTES ANAEROBIC DIGESTATE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane gas resulting from combining cotton gin trash and dairy manure in a two phase anaerobic digester is easily marketed. Digestate solids are not. This study was conducted to determine anaerobic digestate toxicity and its potential as a soil amendment. The same mixture of dairy manure and cot...

  18. Anaerobic Co-Digestion on Dairies in Washington State

    E-print Network

    Collins, Gary S.

    1 Anaerobic Co-Digestion on Dairies in Washington State The solid waste handling permit exemption W This factsheet briefly reviews the role of co-digestion within anaerobic digestion (AD), explains the potential digestion facilities that digest dairy manure have begun to co-digest pre-consumer organic wastes (such

  19. Net greenhouse gas emissions from manure management using anaerobic digestion technology in a beef cattle feedlot in Brazil.

    PubMed

    Costa Junior, Ciniro; Cerri, Carlos E P; Pires, Alexandre V; Cerri, Carlos C

    2015-02-01

    As part of an agreement during the COP15, the Brazilian government is fostering several activities intended to mitigate greenhouse gas (GHG) emissions. One of them is the adoption of anaerobic digester (AD) for treating animal manure. Due to a lack of information, we developed a case study in order to evaluate the effect of such initiative for beef cattle feedlots. We considered the net GHG emissions (CH4 and N2O) from the manure generated from 140 beef heifers confined for 90 days in the scope "housing to field application" by including field measurements, literature values, and the offset generated by the AD system through the replacement of conventional sources of nitrogen (N) fertilizer and electricity, respectively. Results showed that direct GHG emissions accounted for 0.14 ± 0.06 kg of carbon dioxide equivalent (CO?eq) per kg of animal live weight gain (lwg), with ~80% originating from field application, suggesting that this emission does not differ from the conventional manure management (without AD) typically done in Brazil (0.19 ± 0.07 kg of CO?eq per kg lwg(-1)). However, 2.4 MWh and 658.0 kg of N-manure were estimated to be generated as a consequence of the AD utilization, potentially offsetting 0.13 ± 0.01 kg of CO?eq kg lwg(-1) or 95% (±45%) of total direct emissions from the manure management. Although, by replacing fossil fuel sources, i.e. diesel oil, this offset could be increased to 169% (±47%). In summary, the AD has the potential to significantly mitigate GHG emissions from manure management in beef cattle feedlots, but the effect is indirect and highly dependent on the source to be replaced. In spite of the promising results, more and continuous field measurements for decreasing uncertainties and improving assumptions are required. Identifying shortcomings would be useful not only for the effectiveness of the Brazilian government, but also for worldwide plans in mitigating GHG emissions from beef production systems. PMID:25461102

  20. Anaerobic sludge digestion with a biocatalytic additive. [Lactobacillus acidophilus

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Fedde, P.A.

    1982-01-01

    Aimed at improving the process operating characteristics of anaerobic digestion for sludge stabilization and SNG production, this study evaluates the effects of a lactobacillus additive under normal, variable, and overload conditions. This whey fermentation product of an acid-tolerant strain of L. acidophilus fortified with CoCO/sub 3/, (NH/sub 4/)/sub 2/HPO/sub 4/, ferrous lactate, and lactic acid provides growth factors, metabolic intermediates, and enzymes needed for substrate degradation and cellular synthesis. Data indicate that the biochemical additive increases methane yield, gas production rate, and volatile solids reduction; decreases volatile acids accumulation; enhances the digester buffer capacity; and improves the fertilizer value and dewatering characteristics of the digested residue. Digester capacities could be potentially doubled when the feed is so treated. Results of field tests with six full-scale digesters confirm observations made with bench-scale digesters.

  1. Pretreatment followed by anaerobic digestion of secondary sludge for reduction of sewage sludge volume.

    PubMed

    Abe, Naoki; Tang, Yue-Qin; Iwamura, Makoto; Morimura, Shigeru; Kida, Kenji

    2013-01-01

    The influence of two pretreatment methods, thermal treatment and low-pressure wet oxidation, on the sludge digestion efficiency was examined. Batch thermophilic anaerobic digestion was used to evaluate the effectiveness of the pretreatment methods in terms of volatile suspended solids (VSS) digestion efficiency and gas production. The results showed that the gas production was not proportional to the VSS degradation efficiency of either thermal treatment or low-pressure wet oxidation. Low-pressure wet oxidation treatment at 150 °C along with 40% of the theoretical oxygen required to oxidize organic carbon gave the highest gas production and the VSS digestion efficiency of 77% at a VSS loading rate of 8 g l(-1) d(-1). The digestion efficiency was about 30% higher than that of thermophilic anaerobic digestion without sludge pretreatment. Sewage sludge could be treated effectively at a high VSS digestion efficiency with this pretreatment followed by thermophilic anaerobic digestion. PMID:23752385

  2. Anaerobic digestion of industrial activated aerobic sludge

    SciTech Connect

    Goodloe, J.G.; Roberts, R.S.

    1990-04-01

    The Tennessee Eastman Company manufactures a variety of organic chemicals, plastics and fibers at their Kingsport Tennessee Facility. The wastewater generated during the manufacture of these compounds is currently treated using an activated sludge process. The objective of the project is to evaluate the economic potential of an anaerobic digestion process to convert industrial sludge at the Tennessee Eastman Company into biogas. The evaluation will require collection and analysis of experimental data on the anaerobic digestion of industrial sludge obtained from Kingsport. Although the experiments will be conducted using Tennessee Eastman sludge, these results should be also generally applicable to similar industrial sludge.

  3. Characterization of food waste as feedstock for anaerobic digestion

    Microsoft Academic Search

    Ruihong Zhang; Hamed M. El-Mashad; Karl Hartman; Fengyu Wang; Guangqing Liu; Chris Choate; Paul Gamble

    2007-01-01

    Food waste collected in the City of San Francisco, California, was characterized for its potential for use as a feedstock for anaerobic digestion processes. The daily and weekly variations of food waste composition over a two-month period were measured. The anaerobic digestibility and biogas and methane yields of the food waste were evaluated using batch anaerobic digestion tests performed at

  4. Kinetics of inactivation of indicator pathogens during thermophilic anaerobic digestion

    E-print Network

    Kinetics of inactivation of indicator pathogens during thermophilic anaerobic digestion Sudeep C Thermophilic anaerobic digestion Pathogen inactivation Ascaris suum Helminth eggs Poliovirus Enteric viruses a b s t r a c t Thermophilic anaerobic sludge digestion is a promising process to divert waste

  5. Degradation of volatile fatty acids in highly efficient anaerobic digestion

    Microsoft Academic Search

    Qunhui Wang; Masaaki Kuninobu; Hiroaki I Ogawa; Yasuhiko Kato

    1999-01-01

    To improve the efficiency of anaerobic digestion, we examined the effects of C2–C6 volatile fatty acids (VFAs) on methane fermentation, as well as the behavior of VFAs in anaerobic digestion. The VFA concentrations and methane production in anaerobic digestion were increased by pretreatment of waste activated sludge (WAS), such as ultrasonic disintegration, thermal and freezing treatments. The major intermediate products

  6. The IWA Anaerobic Digestion Model No 1 (ADM1)

    Microsoft Academic Search

    D. J. Batstone; J. Keller; I. Angelidaki; S. V. Kalyuzhnyi; S. G. Pavalostathis; A. Rozzi; W. T. M. Sanders; H. Siegrist; V. A. Vavilin

    2002-01-01

    The IWA Anaerobic Digestion Modelling Task Group was established in 1997 at the 8th World Congress on Anaerobic Digestion (Sendai, Japan) with the goal of developing a generalised anaerobic digestion model. The structured model includes multiple steps describing biochemical as well as physicochemical processes. The biochemical steps include disintegration from homogeneous particulates to carbohydrates, proteins and lipids; extracellular hydrolysis of

  7. Operational characteristics of anaerobic digesters at selected wastewater-treatment facilities in the United States

    NASA Astrophysics Data System (ADS)

    1981-07-01

    The effectiveness of powered activated carbon in improving volatile solids destruction and gas production in anaerobic digesters that are operating at less than normally expected levels of efficiency was studied. Digester operating characteristics were surveyed and the number of stressed digesters estimated. It is shown that although median values of the operating parameters conformed with those of a well operated digester, 30 percent of the digesters surveyed were stressed with regard to at least one important parameter. Digester gas production and usage are examined to determine the importance of methane off gas as an energy source. Onsite uses include heating digesters and buildings, incinerating sludge, operating equipment, and generating electricity.

  8. Anaerobic Digestion in a Flooded Densified Leachbed

    NASA Technical Reports Server (NTRS)

    Chynoweth, David P.; Teixeira, Arthur A.; Owens, John M.; Haley, Patrick J.

    2009-01-01

    A document discusses the adaptation of a patented biomass-digesting process, denoted sequential batch anaerobic composting (SEBAC), to recycling of wastes aboard a spacecraft. In SEBAC, high-solids-content biomass wastes are converted into methane, carbon dioxide, and compost.

  9. Pulse power enhancement of the anaerobic digester process

    SciTech Connect

    Greene, H.W. [Scientific Utilization, Inc., Huntsville, AL (United States)

    1996-12-31

    A pilot study of the effects of Pulse Power Processing on an anaerobic digester system was completed at the Decatur Utilities Dry Creek Wastewater Treatment Plant, in Decatur Alabama, in September, 1995. This patented method generates several significant effects when all biosolids material is treated as it enters the anaerobic system. Intense, high peak-power plasma arcs are created, one at each end of the parabolic processing chamber, to produce an amplified synergy of alterations to the digester sludge flowing between them. The millisecond electric discharges generate localized temperatures as high as 30,000 K{degrees}, followed by a rapid cooling of the flowing liquid, which produces acoustic shock waves with pressures approaching 5,000 atmospheres. This destructive force: ruptures many of the cell walls of the bacteria and other single-cell organisms, releasing their vacuole fluids; breaks carbon bonds to form smaller organic compounds; and pulverizes large particle conglomerates, increasing the overall surface area of the solids. These beneficial results serve to boost the nutrient source for the anaerobes in the digester. In conjunction with LTV radiation, the formation of excited chemical radicals (including OH{sup -}), and the changes in ionic charge through alteration of the zeta potential, the bioreactor system is turbocharged to enhance the conversion of volatile biosolids to methane gas, which is the natural respiratory by-product of anaerobic digestion.

  10. Photoenhanced anaerobic digestion of organic acids

    SciTech Connect

    Weaver, P.F.

    1989-08-25

    A process is described for rapid conversion of organic acids and alcohols in anaerobic digesters into hydrogen and carbon dioxide, the optimal precursor substrates for production of methane. The process includes addition of photosynthetic bacteria to the digester and exposure of the bacteria to radiant energy (e.g., solar energy). The process also increases the pH stability of the digester to prevent failure of the digester. Preferred substrates for photosynthetic bacteria are the organic acid and alcohol waste products of fermentative bacteria. In mixed culture with methanogenic bacteria or in defined co-culture with non-aceticlastic methanogenic bacteria, photosynthetic bacteria are capable of facilitating the conversion of organic acids and alcohols into methane with low levels of light energy input. 8 figs.

  11. Photoenhanced anaerobic digestion of organic acids

    SciTech Connect

    Weaver, P.F.

    1990-04-24

    This patent describes a process for rapid conversion of organic acids and alcohols in anaerobic digesters into hydrogen and carbon dioxide, the optimal precursor substrates for production of methane. The process includes addition of photosynthetic bacteria to the digester and exposure of the bacteria to radiant energy (solar energy). The process also increases the pH stability of the digester to prevent failure of the digester. Preferred substrates for photosynthetic bacteria are the organic acid and alcohol waste products of fermentative bacteria. In mixed culture with methanogenic bacteria or in defined co-culture with non-aceticlastic methanogenic bacteria, photosynthetic bacteria are capable of facilitating the conversion or organic acids and alcohols into methane with low levels of light energy input.

  12. Photoenhanced anaerobic digestion of organic acids

    DOEpatents

    Weaver, Paul F. (Golden, CO)

    1990-01-01

    A process is described for rapid conversion of organic acids and alcohols anaerobic digesters into hydrogen and carbon dioxide, the optimal precursor substrates for production of methane. The process includes addition of photosynthetic bacteria to the digester and exposure of the bacteria to radiant energy (e.g., solar energy). The process also increases the pH stability of the digester to prevent failure of the digester. Preferred substrates for photosynthetic bacteria are the organic acid and alcohol waste products of fermentative bacteria. In mixed culture with methanogenic bacteria or in defined co-culture with non-aceticlastic methanogenic bacteria, photosynthetic bacteria are capable of facilitating the conversion or organic acids and alcohols into methane with low levels of light energy input.

  13. A methane production feasibility model for central anaerobic digesters

    NASA Astrophysics Data System (ADS)

    Sullivan, J. L.; Peters, N.; Ostrovski, C. M.

    1981-01-01

    A mathematical model was developed for prediction of the practicability of building and operating large centrally located anaerobic digesters for producing methane gas from animal manure. The assumptions were that the manure would be collected from the feedlots and that the product gas would be supplied to an existing pipeline. The model takes account of the farm locations and calculates transportation costs for various numbers of digesters. Digester sizes for each distribution and installation and operating costs are computed. Revenue was then determined on the basis of methane production and fertilizer value recovery. The utility of the model is shown through a study of farms in southwestern Ontario where many small feedlots exist. The results of the study indicate a gas production cost of roughly $0.18/cu m.

  14. Contribution of Anaerobic Digesters to Emissions Mitigation and Electricity Generation Under U.S. Climate Policy

    E-print Network

    Zaks, David P. M.

    Livestock husbandry in the U.S. significantly contributes to many environmental problems, including the release of methane, a potent greenhouse gas (GHG). Anaerobic digesters (ADs) break down organic wastes using bacteria ...

  15. Flow pattern visualization in a mimic anaerobic digester using CFD.

    PubMed

    Vesvikar, Mehul S; Al-Dahhan, Muthanna

    2005-03-20

    Three-dimensional steady-state computational fluid dynamics (CFD) simulations were performed in mimic anaerobic digesters to visualize their flow pattern and obtain hydrodynamic parameters. The mixing in the digester was provided by sparging gas at three different flow rates. The gas phase was simulated with air and the liquid phase with water. The CFD results were first evaluated using experimental data obtained by computer automated radioactive particle tracking (CARPT). The simulation results in terms of overall flow pattern, location of circulation cells and stagnant regions, trends of liquid velocity profiles, and volume of dead zones agree reasonably well with the experimental data. CFD simulations were also performed on different digester configurations. The effects of changing draft tube size, clearance, and shape of the tank bottoms were calculated to evaluate the effect of digester design on its flow pattern. Changing the draft tube clearance and height had no influence on the flow pattern or dead regions volume. However, increasing the draft tube diameter or incorporating a conical bottom design helped in reducing the volume of the dead zones as compared to a flat-bottom digester. The simulations showed that the gas flow rate sparged by a single point (0.5 cm diameter) sparger does not have an appreciable effect on the flow pattern of the digesters at the range of gas flow rates used. PMID:15685599

  16. Anaerobic digestion of organic solid poultry slaughterhouse waste – a review

    Microsoft Academic Search

    E. Salminen; J. Rintala

    2002-01-01

    This work reviews the potential of anaerobic digestion for material recovery and energy production from poultry slaughtering by-products and wastes. First, we describe and quantify organic solid by-products and wastes produced in poultry farming and poultry slaughterhouses and discuss their recovery and disposal options. Then we review certain fundamental aspects of anaerobic digestion considered important for the digestion of solid

  17. Ultrasound Pretreatment of Sludge for Anaerobic Digestion

    Microsoft Academic Search

    Kuan Yeow Show; Joo Hwa Tay; Yung-Tse Hung

    \\u000a Ultrasound pretreatment of sludge has been examined in an effort to improve the hydrolysis rate in anaerobic digestion. The\\u000a reactions that resulted from the generation and collapse of cavitation bubbles produced under the acoustic condition can significantly\\u000a modify the substances present in the sludge. The principles of ultrasound that encompass acoustic cavitation and bubble dynamics,\\u000a the mechanisms of biological damage

  18. Anaerobic digestion of banana stem waste

    Microsoft Academic Search

    V. C Kalia; V Sonakya; N Raizada

    2000-01-01

    Waste banana stem has a high organic content (83%); with 15–20% (w\\/w) lignin and cellulose which gives it a sheath-like texture. Banana stem slurries (BSS) at 2–16% total solids (TS) concentration were anaerobically digested under mesophilic (37–40°C) as well as thermophilic conditions (50–55°C) in batch culture. The final biogas yields, 267–271 l\\/kg TS fed, were observed with 2–4% TS slurries,

  19. Hog farm in California uses anaerobic digestion

    SciTech Connect

    Swanson, D. [Western Area Power Administration, Golden, CO (United States)

    1995-12-31

    This article describes a system of covered lagoons which help address the waste management problems of hog farmers as well as producing methane used to power generators. Four advantages of anaerobic digestion are described along with the system: energy production from methane; fertilizer for fields; economic development in rural areas; and improved water quality through reduction of nonpoint source pollution. Address for full report is given.

  20. Ultrasonic sludge treatment for enhanced anaerobic digestion.

    PubMed

    Hogan, F; Mormede, S; Clark, P; Crane, M

    2004-01-01

    Ultrasound is the term used to describe sound energy at frequencies above 20 kHz. High-powered ultrasound can be applied to a waste stream via purpose-designed tools in order to induce cavitation. This effect results in the rupture of cellular material and reduction of particle size in the waste stream, making the cells more amenable to downstream processing. sonix is a new technology utilising high-powered, concentrated ultrasound for conditioning sludges prior to further treatment. This paper presents recent results from a number of demonstration and full-scale plants treating thickened waste activated sludge (TWAS) prior to anaerobic digestion, therefore enhancing the process. The present studies have proved that the use of ultrasound to enhance anaerobic digestion can be achieved at full scale and effectively result in the TWAS (typically difficult to digest) behaving, after sonication, as if it were a "primary" sludge. The technology presents benefits in terms of increased biogas production, better solids reduction, improved dewatering characteristics of the digested sludge mixture and relatively short payback periods of two years or less subject to the site conditions and practices applicable at that time. PMID:15580991

  1. Processing anaerobic sludge for extended storage as anaerobic digester inoculum.

    PubMed

    Li, Jiajia; Zicari, Steven M; Cui, Zongjun; Zhang, Ruihong

    2014-08-01

    Thermophilic anaerobic sludge was processed to reduce the volume and moisture content in order to reduce costs for storing and transporting the sludge as microbial inoculum for anaerobic digester startup. The moisture content of the sludge was reduced from 98.7% to 82.0% via centrifugation and further to 71.5% via vacuum evaporation. The processed sludge was stored for 2 and 4 months and compared with the fresh sludge for the biogas and methane production using food waste and non-fat dry milk as substrates. It was found that fresh unprocessed sludge had the highest methane yield and the yields of both unprocessed and processed sludges decreased during storage by 1-34%, however processed sludges seemed to regain some activity after 4 months of storage as compared to samples stored for only 2 months. Maximum methane production rates obtained from modified Gompertz model application also increased between the 2-month and 4-month processed samples. PMID:24907580

  2. Balancing hygienization and anaerobic digestion of raw sewage sludge.

    PubMed

    Astals, S; Venegas, C; Peces, M; Jofre, J; Lucena, F; Mata-Alvarez, J

    2012-12-01

    The anaerobic digestion of raw sewage sludge was evaluated in terms of process efficiency and sludge hygienization. Four different scenarios were analyzed, i.e. mesophilic anaerobic digestion, thermophilic anaerobic digestion and mesophilic anaerobic digestion followed by a 60 °C or by an 80 °C hygienization treatment. Digester performance (organic matter removal, process stability and biogas yield) and the hygienization efficiency (reduction of Escherichia coli, somatic coliphages and F-specific RNA phages) were the main examined factors. Moreover, a preliminary economical feasibility study of each option was carried out throughout an energy balance (heat and electricity). The obtained results showed that both thermophilic anaerobic digestion and mesophilic anaerobic digestion followed by a hygienization step were able to produce an effluent sludge that fulfills the American and the European legislation for land application. However, higher removal efficiencies of indicators were obtained when a hygienization post-treatment was present. Regarding the energy balance, it should be noted that all scenarios have a significant energy surplus. Particularly, positive heat balances will be obtained for the thermophilic anaerobic digestion and for the mesophilic anaerobic digestion followed by 60 °C hygienization post-treatment if an additional fresh-sludge/digested sludge heat exchanger is installed for energy recovery. PMID:23063441

  3. Sequencing mesophilic and thermophilic anaerobic digesters. Final report

    SciTech Connect

    Not Available

    1982-12-01

    This project employed two laboratory bench scale, complete-mix anaerobic sludge digesters arranged in a series configuration. The first digester was operated at 35/sup 0/C (mesophilic) and the second at 50/sup 0/C (thermophilic). A portion of the thermophilic sludge was recycled through an aeration basin. As a comparison to the mesophilic-thermophilic sequencing, a mesophilic-mesophilic digester sequence, without sludge recycle to the aeration basin, was operated in parallel to the test units and loaded at an equivalent rate. Conclusions of this study are as follows: in establishing a thermophilic anaerobic digester, a slow-start procedure, in which the temperature is increased at a rate of 0.6/sup 0/C per day with loading, appears to produce a more stable thermophilic digester in a shorter period of time than a quick-start procedure, in which the temperature is increased rapidly with no loading. Even after a year, the slow-start thermophilic digester proved to be unstable once sequencing began. A greater volatile solids, COD, BOD, and grease reduction with a higher gas production was achieved using a mesophilic-mesophilic sequence, probably, in part, due to the instability (volatile acids in the effluent) of the thermophilic digester in the mesophilic-thermophilic sequence. A greater total kjeldahl N (TKN) and total coliform destruction was achieved in the thermophilic digester, however, poor dewatering characteristics, as indicated by the capillary suction time (CST), and an obnoxious odor were also evident. Other than an increase in effluent suspended solids, the recycle of thermophilic sludge to an aeration basin produced no discernable effect. 9 figs., 3 tabs.

  4. DESIGN OF SOFTWARE SENSORS FOR UNMEASURABLE VARIABLES OF ANAEROBIC DIGESTION PROCESSES

    E-print Network

    Boyer, Edmond

    DESIGN OF SOFTWARE SENSORS FOR UNMEASURABLE VARIABLES OF ANAEROBIC DIGESTION PROCESSES Simeonov, I variables of anaerobic digestion processes. For this purpose, different mathematical models of anaerobic digestion and different theoretical approaches (differential algebraic approach, Kalman filter modifications

  5. On a Three Step Model of Anaerobic Digestion Including the Hydrolysis of

    E-print Network

    Paris-Sud XI, Université de

    On a Three Step Model of Anaerobic Digestion Including the Hydrolysis of Particulate Matter R degradation, chemostat, models, growth rate, equilibrium, bistability. 1. INTRODUCTION Anaerobic digestion, the anaerobic digestion is generally considered as a three step process: hydrolysis and liquefaction

  6. Anaerobic digestion of fish processing by-products

    Microsoft Academic Search

    Chris Ward; Bill Slater

    2002-01-01

    Anaerobic digestion can be used to treat many organic waste streams. However, fish wastes pose a particular technological problem, as they release high levels of ammonia when digested, which then inhibits the digestion process. Having overcome these technical problems, it is important that there is a long term, financially viable outlet for the products of the digestion process. The organic

  7. DEMONSTRATION OF FUEL CELLS TO RECOVER ENERGY FROM AN ANAEROBIC DIGESTER GAS - PHASE I. CONCEPTUAL DESIGN, PRELIMINARY COST, AND EVALUATION STUDY

    EPA Science Inventory

    The report discusses Phase I (a conceptual design, preliminary cost, and evaluation study) of a program to demonstrate the recovery of energy from waste methane produced by anaerobic digestion of waste water treatment sludge. he fuel cell is being used for this application becaus...

  8. Bioaugmentation of overloaded anaerobic digesters restores function and archaeal community.

    PubMed

    Tale, V P; Maki, J S; Zitomer, D H

    2015-03-01

    Adding beneficial microorganisms to anaerobic digesters for improved performance (i.e. bioaugmentation) has been shown to decrease recovery time after organic overload or toxicity upset. Compared to strictly anaerobic cultures, adding aerotolerant methanogenic cultures may be more practical since they exhibit higher methanogenic activity and can be easily dried and stored in ambient air for future shipping and use. In this study, anaerobic digesters were bioaugmented with both anaerobic and aerated, methanogenic propionate enrichment cultures after a transient organic overload. Digesters bioaugmented with anaerobic and moderately aerated cultures recovered 25 and 100 days before non-bioaugmented digesters, respectively. Increased methane production due to bioaugmentation continued a long time, with 50-120% increases 6 to 12 SRTs (60-120 days) after overload. In contrast to the anaerobic enrichment, the aerated enrichments were more effective as bioaugmentation cultures, resulting in faster recovery of upset digester methane and COD removal rates. Sixty days after overload, the bioaugmented digester archaeal community was not shifted, but was restored to one similar to the pre-overload community. In contrast, non-bioaugmented digester archaeal communities before and after overload were significantly different. Organisms most similar to Methanospirillum hungatei had higher relative abundance in well-operating, undisturbed and bioaugmented digesters, whereas organisms similar to Methanolinea tarda were more abundant in upset, non-bioaugmented digesters. Bioaugmentation is a beneficial approach to increase digester recovery rate after transient organic overload events. Moderately aerated, methanogenic propionate enrichment cultures were more beneficial augments than a strictly anaerobic enrichment. PMID:25528544

  9. State Of The Science On Cogeneration Of Heat And Power From Anaerobic Digestion Of Municipal Biosolids

    EPA Science Inventory

    This presentation will report on work underway to inventory facilities currently utilizing biogas from anaerobic digestion and speak with practitioners to learn: techniques for preparing residuals for digestion, methods to use for cleaning biogas (e.g., of siloxane), and how gas...

  10. Kinetic model for anaerobic digestion of waste activated sludge

    SciTech Connect

    Pavlostathis, S.G.

    1985-01-01

    Although numerous reports exist in the literature concerning the anaerobic digestion of waste activated sludge (WAS), there are no kinetic models available to describe anaerobic process performance with a WAS feed source. Anaerobic digestion models which consider methanogenesis rate-limiting are inapplicable in the case of WAS. Preliminary conversion mechanisms such as death, lysis and hydrolysis play an important role in the anaerobic digestion of biological sludges. The principal objectives of the present study were: (a) to elucidate the role of the above-described conversion mechanisms in rendering viable WAS organisms into available substrate for the anaerobic microorganisms; (b) to develop and evaluate a comprehensive kinetic model capable of predicting digester performance when fed WAS. In order to meet the above-stated objectives, laboratory-scale anaerobic digesters were operated on an automatic, hourly feed cycle. The hydraulic retention times employed ranged from approximately 1 day to 25 days. The results of this study indicate that viable WAS cell death and lysis, and hydrolysis of the dead particulate biomass constitute a kinetic barrier in the conversion of biological solids to available substrate for the anaerobic digester microflora. Hydrolysis was found to be the slowest step, and therefore kinetically controls the overall process of anaerobic digestion of biological solids. A kinetic model was developed which could accurately describe digester performance and predict effluent quality.

  11. Bioreactor performance in anaerobic digestion of fruit and vegetable wastes

    Microsoft Academic Search

    H. Bouallagui; Y. Touhami; R. Ben Cheikh; M. Hamdi

    2005-01-01

    This work reviews the potential of anaerobic digestion for material recovery and energy production from fruit and vegetable wastes (FVW). These wastes contain 8–18% total solids (TS), with a total volatile solids (VS) content of 86–92%. The organic fraction includes about 75% easy biodegradable matter (sugars and hemicellulose), 9% cellulose and 5% lignin. Anaerobic digestion of FVW was studied under

  12. Anaerobic digestion Of a Petrochemical Wastewater using the UASB process

    Microsoft Academic Search

    J. P. Guyot; H. Macarie; A. Noyola

    1990-01-01

    Anaerobic digestion of effluent from a petrochemical plant producing terephthalic acid has been tested using two Upflow Anaerobic\\u000a Sludge Blanket (USAB) reactors. The reactors were seeded with two different inocula: one from an anaerobic stabilization pond\\u000a receiving wasted sludge from the aerobic treatment plant of the petrochemical industry (reactor A); the other was an anaerobically\\u000a adapted activated sludge from a

  13. Methane enrichment digestion experiments at the anaerobic experimental test unit at Walt Disney World. Final report, March 1989-August 1990

    SciTech Connect

    Srivastava, V.J.; Hill, A.H.

    1993-06-01

    The goal of the project was to determine the technical feasibility of utilizing a novel concept in anaerobic digestion, in-situ methane enrichment digestion or MED for producing utility-grade gas from a pilot-scale anaerobic digester. MED tests conducted during this program consistently achieved digester product gas with a methane (CH4) content of greater than 90% (on a dry-, nitrogen-free basis). The MED concept, because it requires relatively simple equipment and modest energy input, has the potential to simplify gas cleanup requirements and substantially reduce the cost of converting wastes and biomass to pipeline quality gas.

  14. Inactivation of dairy manure-borne pathogens by anaerobic digestion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Anaerobic digestion of animal manure has the potential to inactivate enteric pathogens, thereby reducing exposures to livestock and humans when the products of digestion are disposed by land-spreading or irrigation or returned to livestock uses such as bedding. Data on digester effectiv...

  15. Anaerobic digestion for methane generation and ammonia reforming for hydrogen production

    E-print Network

    Anaerobic digestion for methane generation and ammonia reforming for hydrogen production Accepted 24 May 2013 Available online Keywords: Anaerobic digestion Ammonia Bioenergy Bioammonia Hydrogen Anaerobic digestion-bioammonia to hydrogen (ADBH) a b s t r a c t During anaerobic digestion, organic matter

  16. Extractability of heavy metals in wastewater solids undergoing anaerobic digestion

    SciTech Connect

    Chen, D.D.

    1983-01-01

    The extractability of heavy metals in wastewater sludge undergoing anaerobic digestion was investigated. Using batch laboratory digesters, raw wastewater sludge was anaerobically digested at different raw sludge solids loadings and two temperatures. From each of the laboratory digesters, wastewater sludge was sampled at three day intervals and sequentially separated into seven extraction fractions and analyzed for the metals Cu, Cr, Cd, Fe, Ni, and Pb. The seven step sequential extraction was for metal species: (a) soluble, (b) displaced-exchangeable, (c) adsorbed, (d) organic, (e) carbonate, (f) sulfide-acid soluble, and (g) residual. At the 35/sup 0/C digestion temperature the distribution of metals in the extractant fractions between the raw and anaerobically digested sludges were significantly different. For the 45/sup 0/C digestion temperature the distribution of metals in the raw and digested sludge extractant fractions were different and different compared to the 35/sup 0/C system. The 45/sup 0/C raw sludge showed greater percent metal in the organic and sulfide-acid soluble fraction than the digested sludge. At the 45/sup 0/C anaerobic digestion temperature the percent of raw sludge solids loading in the digester had a greater effect on changes in metal extractability and proposed metal species than the 35/sup 0/C.

  17. Anaerobic biodegradation of nitroglycerin by digester sludge

    SciTech Connect

    Christodoulatos, C.; Pal, N.; Bhaumik, S. [Stevens Inst. of Technology, Hoboken, NJ (United States). Center for Environmental Engineering

    1995-12-31

    Nitroglycerin (NG) is an energetic compound primarily present in gun and rocket propellants as a primary explosive. It was also abundantly found in spent wastes from several chemical or pharmaceutical industries and in the wastewater of munitions manufacturing facilities causing significant environmental pollution. Incineration, other thermal processes, and chemical treatment such as acid or alkaline hydrolysis can effectively destroy these high energy compounds but they are associated with high treatment costs. Moreover, chemical processes may generate waste streams which require further treatment prior to their discharge in the environment. There is therefore, a pressing need for the development of new technologies that can economically and effectively deal with the disposal of energetic compounds. Biological treatment of energetic compounds amenable to microbial degradation provides an alternative to costly thermal and chemical methods. NG can be aerobically biodegraded by several fungal and bacterial consortia in the presence of co-substrates. The decomposition proceeds through a number of intermediate products whose formation is catalyzed by extra-cellular enzymes. The anaerobic biodegradation of NG by a mixed bacterial culture from digester sludge was investigated in this study. the study focused on the ability of anaerobic bacteria to degrade NG and utilize it as sole carbon source, the identification of possible intermediates,and the effect of co-substrates on the rates of transformation.

  18. Methane conversion efficiency as a simple control parameter for an anaerobic digester at high loading rates.

    PubMed

    Charles, W; Carnaje, N P; Cord-Ruwisch, R

    2011-01-01

    The anaerobic digestion process is globally applied to the treatment of highly concentrated wastes such as industrial and rural effluents, and sewage sludge. However, it is known to be relatively unstable. When loaded with high concentrations of organic material, unwanted volatile fatty acids (VFA) are often produced rather than methane (CH4) gas which can lead to digester acidification and failure. This study investigated digester behaviour under high loading rates, testing the usefulness of stoichiometric methane conversion efficiency as a digester control parameter at high loading rates. Our results show that, in general, the CH4 production rate was proportional to the feed rate (loading rate). However, at very high loading rates, the CH4 production rate was not proportional to the increase in the feeding rate. Consequently, VFA accumulated and the H2 partial pressure increased. The proportionality of the loading rate and gas production rate is stoichiometrically expressed as the conversion efficiency. We found that conversion efficiency was a useful indicator as an early warning of digester imbalance. The digester remained stable at conversion efficiencies above 75%. Dropping below 70% signified the onset of digester failure. As loading rate and methane production data are readily available on-line in most anaerobic digestion plants, the conversion efficiency can be monitored on-line and used as an efficient control technique to maintain safe operation of anaerobic digesters at high loading rates. PMID:22097030

  19. Greenhouse gas production: A comparison between aerobic and anaerobic wastewater treatment technology

    Microsoft Academic Search

    F. Y. Cakir; M. K. Stenstrom

    2005-01-01

    Anaerobic wastewater treatment offers improved energy conservation with potential reduction in greenhouse gas emissions. Pitfalls exist in that the methane produced in anaerobic treatment can offset any reductions in carbon dioxide emissions, if it is released to the environment. This paper analyzes greenhouse gas emissions from both aerobic and anaerobic treatment systems, including sludge digestion and the losses of dissolved

  20. INCREASE OF INDICATOR ORGANISMS FOLLOWING ANAEROBIC DIGESTION AND CENTRIFUGE DEWATERING.

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled ?Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges?. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bac...

  1. Environmental impacts of anaerobic digestion and the use of anaerobic residues as soil amendment

    SciTech Connect

    Mosey, F.E. [VFA Services Ltd., Herts (United Kingdom)

    1996-01-01

    This paper defines the environmental role of anaerobic digestion within the overall objective of recovering energy from renewable biomass resources. Examples and opportunities for incorporating anaerobic digestion into biomass-to-energy schemes are discussed, together with environmental aspects of anaerobic digestion plants. These include visual, public amenity, pathogens and public health, odor control, and gaseous emissions. Digestate disposal and the benefits of restrictions on recycling organic wastes and biomass residues back to the land are discussed, particularly as they relate to American and European codes of practice and environmental legislation. The paper concludes that anaerobic digestion, if performed in purpose-designed reactors that efficiently recover and use biogas, is an environmentally benign process that can enhance energy recovery and aid the beneficial land use of plant residues in many biomass-to-energy schemes.

  2. Environmental impacts of anaerobic digestion and the use of anaerobic residues as soil amendment

    SciTech Connect

    Mosey, F.E. [VFA Services Ltd., Herts (United Kingdom)

    1995-11-01

    This paper defines the environmental role of anaerobic digestion with the overall objective of recovering energy from renewable biomass resources. Examples and opportunities for incorporating anaerobic digestion into biomass-to-energy schemes are discussed, together with environmental aspects of anaerobic digestion plants. These include visual, public amenity, pathogens and public health, odor control, and gaseous emissions. Digestate disposal and the benefits of restrictions on recycling organic wastes and biomass residues back to the land are discussed, particularly as they relate to American and European codes of practice and environmental legislation. The paper concludes that anaerobic digestion, if performed in purpose-designed reactors that efficiently recover and use biogas, if performed in purpose-designed reactors that efficiently recover and use biogas, is an environmentally benign process that can enhance energy recovery and aid the beneficial land use of plant residues in many biomass-to-energy schemes.

  3. Using contaminated plants involved in phytoremediation for anaerobic digestion.

    PubMed

    Cao, Zewei; Wang, Shengxiao; Wang, Ting; Chang, Zhizhou; Shen, Zhenguo; Chen, Yahua

    2015-01-01

    This study investigated the anaerobic digestion capability of five plants and the effects of copper (Cu) and S,S'-ethylenediaminedisuccinic acid (EDDS, a chelator widely used in chelant-assisted phytoremediation) on biogas production to determine a feasible disposal method for plants used in remediation. The results showed that in addition to Phytolacca americana L., plants such as Zea mays L., Brassica napus L., Elsholtzia splendens Nakai ex F. Maekawa, and Oenothera biennis L. performed well in biogas production. Among these, O. biennis required the shortest period to finish anaerobic digestion. Compared to normal plants with low Cu content, the plants used in remediation with increased Cu levels (100 mg kg(-1)) not only promoted anaerobic digestion and required a shorter anaerobic digestion time, but also increased the methane content in biogas. When the Cu content in plants increased to 500, 1000, and 5000 mg kg(-1), the cumulative biogas production decreased by 12.3%, 14.6%, and 41.2%, respectively. Studies also found that EDDS conspicuously restrained biogas production from anaerobic digestion. The results suggest that anaerobic digestion has great potential for the disposal of contaminated plants and may provide a solution for the resource utilization of plants used in remediation. PMID:25397976

  4. Industrial symbiosis: corn ethanol fermentation, hydrothermal carbonization, and anaerobic digestion.

    PubMed

    Wood, Brandon M; Jader, Lindsey R; Schendel, Frederick J; Hahn, Nicholas J; Valentas, Kenneth J; McNamara, Patrick J; Novak, Paige M; Heilmann, Steven M

    2013-10-01

    The production of dry-grind corn ethanol results in the generation of intermediate products, thin and whole stillage, which require energy-intensive downstream processing for conversion into commercial animal feed products. Hydrothermal carbonization of thin and whole stillage coupled with anaerobic digestion was investigated as alternative processing methods that could benefit the industry. By substantially eliminating evaporation of water, reductions in downstream energy consumption from 65% to 73% were achieved while generating hydrochar, fatty acids, treated process water, and biogas co-products providing new opportunities for the industry. Processing whole stillage in this manner produced the four co-products, eliminated centrifugation and evaporation, and substantially reduced drying. With thin stillage, all four co-products were again produced, as well as a high quality animal feed. Anaerobic digestion of the aqueous product stream from the hydrothermal carbonization of thin stillage reduced chemical oxygen demand (COD) by more than 90% and converted 83% of the initial COD to methane. Internal use of this biogas could entirely fuel the HTC process and reduce overall natural gas usage. PMID:23568780

  5. Anaerobic digestion of water hyacinth and sludge

    SciTech Connect

    Biljetina, R.; Srivastava, V.J.; Chynoweth, D.P.; Hayes, T.D.

    1986-01-01

    The Institute of Gas Technology (IGT) has been operating an experimental test unit (ETU) at the Walt Disney World (WDW) wastewater treatment plant to demonstrate the conversion of water hyacinth and sludge to methane in a solids concentrating (SOLCON) digester. Results from 2 years to operation have confirmed earlier laboratory observations that this digester achieves higher methane yields and solids conversion than those observed in continuous stirred tank reactors. Methane yields as high as 0.49 m/sup 3/ kg/sup -1/ (7.9 SCF/lb) volatile solids added have been obtained during steady-state operation on a blend of water hyacinth and sludge. 9 refs., 5 figs., 5 tabs.

  6. Waste-to-wheel analysis of anaerobic-digestion-based renewable natural gas pathways with the GREET model

    Microsoft Academic Search

    J. Han; M. Mintz; M. Wang

    2011-01-01

    In 2009, manure management accounted for 2,356 Gg or 107 billion standard cubic ft of methane (CH) emissions in the United States, equivalent to 0.5% of U.S. natural gas (NG) consumption. Owing to the high global warming potential of methane, capturing and utilizing this methane source could reduce greenhouse gas (GHG) emissions. The extent of that reduction depends on several

  7. Anaerobic digestion of sludge from intensive recirculating aquaculture systems: Review

    Microsoft Academic Search

    Natella Mirzoyan; Yossi Tal; Amit Gross

    2010-01-01

    Intensive recirculating aquaculture systems (RAS) produce high volumes of biosolid waste which is a potential source of pollution if not properly treated. A reduction in sludge-mass would therefore minimize the potential environmental hazard and economic burden stemming from its disposal. Recently, anaerobic digestion was suggested as an alternative to aquaculture sludge digestion and stabilization in RAS. This practice results not

  8. Anaerobic digestion of household organic waste to produce biogas

    Microsoft Academic Search

    Mir-Akbar Hessami; Sky Christensen; Robert Gani

    1996-01-01

    Biogas may be readily obtained by the anaerobic digestion of organic waste. If communities and towns could harness the energy which is contained in the organic waste which they presently dispose of in landfills or compost, this fuel could supplement or completely satisfy their heat energy requirements.Biogas production from household organic waste is rare because existing digesters are not suitable

  9. Applications of the anaerobic digestion process.

    PubMed

    Angelidaki, Irini; Ellegaard, Lars; Ahring, Birgitte Kioer

    2003-01-01

    At the start of the new millennium waste management has become a political priority in many countries. One of the main problems today is to cope with an increasing amount of primary waste in an environmentally acceptable way. Biowastes, i.e., municipal, agricultural or industrial organic waste, as well as contaminated soils etc., have traditionally been deposited in landfills or even dumped into the sea or lakes without much environmental concern. In recent times, environmental standards of waste incineration and controlled land filling have gradually improved, and new methods of waste sorting and resource/energy recovery have been developed. Treatment of biowastes by anaerobic digestion processes is in many cases the optimal way to convert organic waste into useful products such as energy (in the form of biogas) and a fertilizer product. Other waste management options, such as land filling and incineration of organic waste has become less desirable, and legislation, both in Europe and elsewhere, tends to favor biological treatment as a way of recycling minerals and nutrients of organic wastes from society back to the food production and supply chain. Removing the relatively wet organic waste from the general waste streams also results in a better calorific value of the remainder for incineration, and a more stable fraction for land filling. PMID:12747564

  10. Effect of alkaline pretreatment on anaerobic digestion of solid wastes

    SciTech Connect

    Lopez Torres, M. [National Center for Scientific Researcher (CNIC), Environmental Pollution Department (DECA), Ave. 25 y 158, Cubanacan, Playa, Havana City (Cuba)], E-mail: matilde.lopez@cnic.edu.cu; Espinosa Llorens, Ma. del C. [National Center for Scientific Researcher (CNIC), Environmental Pollution Department (DECA), Ave. 25 y 158, Cubanacan, Playa, Havana City (Cuba)

    2008-11-15

    The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH){sub 2}), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH){sub 2}/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m{sup 3} CH{sub 4}/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW.

  11. Economic evaluation of a swine farm covered anaerobic lagoon digester

    SciTech Connect

    Lusk, P. [Resource Development Associates, Washington, DC (United States)

    1996-12-31

    It is helpful to evaluate anaerobic digestion technologies using objective economic criteria. Options can then be ranked in terms of their relative cost effectiveness, leading to rational deployment decisions. This study presents the results of a hypothetical pro forma economic evaluation of one type of digestion system that could commonly be found on many swine farms; a covered anaerobic lagoon. The digester was assumed to be located in North Carolina, a major swine-producing state. Electricity generation with waste heat recovery was assumed to be the major end-use application of biogas manufactured from this process.

  12. Anaerobic digestion of hog wastes: Principles and practice

    SciTech Connect

    Oleszkiewicz, J.A.; Bujoczek, G. [Univ. of Manitoba, Winnipeg (Canada)

    1996-12-31

    The principles and overview of research, development and implementation of anaerobic digestion for hog wastes are discussed. Based on economic evaluations, an anaerobic technology is cost-effective, especially for a larger herd and becomes more competitive with aerobic treatment. Nevertheless, the rate of treatment is more sensitive and dependent on the particular fraction of manure being processed. Considering the different factors affecting anaerobic digestion, a complete mixed reactor with solids recycle (having high solids retention time and low hydraulic retention time) was found to be the more reliable system with regards to methane generation and manure stabilization. By solids recycle one can obtain significant saving in the reactor volume required, while still achieving the expected degree of treatment. It was also found that even though treatment using advanced anaerobic systems when compared with simple anaerobic systems is more expensive, the rate of return on investment and efficiency of the process are higher.

  13. Polychlorinated biphenyl concentration changes in sewage sludge and organic municipal waste mixtures during composting and anaerobic digestion.

    PubMed

    Siebielska, Izabela; Side?ko, Robert

    2015-05-01

    We determined the changes in polychlorinated biphenyl (PCB) concentrations in a mixture of sewage sludge and the organic fraction of municipal waste during composting and during anaerobic digestion. The processes were carried out on a laboratory scale. The PCBs were analyzed in the waste samples using gas chromatography-mass spectrometry. We evaluated the rates at which the PCB concentrations decreased during composting and during anaerobic digestion and compared the PCB degradation kinetics during these processes. The most important conclusion of this work is that anaerobic digestion is much more effective than composting at removing PCBs from a mixture of sewage sludge and the organic fraction of municipal waste. PMID:25618191

  14. Surfactants in anaerobic digestion of cheese whey, poultry waste, and cattle dung for improved biomethanation

    SciTech Connect

    Desai, M.; Madamwar, D. [Sardar Patel Univ., Vallabh Vidyanagar (India)

    1994-05-01

    To obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung, poultry waste and cheese whey, with enriched methane content, the effect of various surfactants was studied. Among the surfactants tested, Tween 80 and sodium lauryl sulphate showed the maximum enhancement in gas production as well as methane content, indicating better process performance. The Tween 80 dosed digester (300 {mu}L/L) produced about 3.5 L gas/L of digester/d with 70% methane. Results also indicated increased percent COD reduction in the presence of Tween 80. 13 refs., 2 figs.

  15. Thermochemical liquidization of anaerobically digested and dewatered sludge and anaerobic retreatment

    Microsoft Academic Search

    Shigeki Sawayama; Seiichi Inoue; Kenichiro Tsukahara; Tomoko Ogi

    1996-01-01

    The pretreatment effect of thermochemical liquidization for the anaerobic retreatment of anaerobically digested and dewatered sludge was studied. The digested sludge (dry matter; 15.7%) was thermochemically liquidized at 175°C and 4 MPa with a holding time of 1 h. The liquidized sludge was separated by centrifugation to produce a supernatant of 44.7% (w\\/w) and precipitate of 52.3%. The liquidized sludge

  16. Biogas by semi-continuous anaerobic digestion of food waste.

    PubMed

    Zhang, Cunsheng; Su, Haijia; Wang, Zhenbin; Tan, Tianwei; Qin, Peiyong

    2015-04-01

    The semi-continuous anaerobic digestion of food waste was investigated in 1-L and 20-L continuously stirred tank reactors (CSTRs), to identify the optimum operation condition and the methane production of the semi-continuous anaerobic process. Results from a 1-L digester indicated that the optimum organic loading rate (OLR) for semi-continuous digestion is 8 g VS/L/day. The corresponding methane yield and chemical oxygen demand (COD) reduction were 385 mL/g VS and 80.2 %, respectively. Anaerobic digestion was inhibited at high OLRs (12 and 16 g VS/L/day), due to volatile fatty acid (VFA) accumulation. Results from a 20-L digester indicated that a higher methane yield of 423 mL/g VS was obtained at this larger scale. The analysis showed that the methane production at the optimum OLR fitted well with the determined kinetics equation. An obvious decrease on the methane content was observed at the initial of digestion. The increased metabolization of microbes and the activity decrease of methanogen caused by VFA accumulation explained the lower methane content at the initial of digestion. PMID:25773980

  17. Reduced gas pressure operation of sludge digesters

    SciTech Connect

    Not Available

    1989-05-01

    This report describes bench-scale research for improving the digestion of sludges. The effects of reduced headspace pressure on anaerobic digester performance was evaluated. Four identical digester systems were constructed for investigating reduced headspace pressure effects. The first system served as a control and was operated with a 1.0 atmosphere gas phase pressures. The remaining three reactors had 0.83, 0.75 and 0.5 atm. gas phase pressures. The reactor systems were housed in a 35 {degrees}C walk-in incubator. Each anaerobic system was designed to simulate the operation of a typical municipal digester. Reactors were seeded with sludge and operated with a 15-day solids retention time (SRT), a typical value for a high-rate digester. This was accomplished by replacing one-fifteenth of the active volume (1.5 liters) with fresh feed daily. Headspace gas pressures were controlled by a pressure-sensitive valve located between the reactor and a large closed vacuum reservoir. Changes in reservoir pressure as a function of time were recorded and used to evaluate gas production. Municipal sludges (3, 5, and 8 percent solids) were used as feedstock for the reactors with 15-day SRTs. A 5 percent sludge was also evaluated with a 25-day SRT. Feed characteristics and reactor pH, alkalinity, total chemical oxygen demand (TCOD), total and volatile suspended solids (TSS and VSS) and gas composition (CH{sub 4}, CO{sub 2}, and H{sub 2}) and production rates were routinely monitored. Total COD, VSS and SS destruction rates along with CH{sub 4} and total gas generation rates were determined as a function of headspace pressure. 25 refs., 41 figs., 13 tabs.

  18. Microbial fuel cells in relation to conventional anaerobic digestion technology

    Microsoft Academic Search

    K. Rabaey; P. Aelterman; P. Clauwaert; L. De Schamphelaire; W. Verstraete

    2006-01-01

    Conventional anaerobic digestion based bioconversion processes produce\\u000a biogas and have as such been widely applied for the production of\\u000a renewable energy so far. An innovative technology, based on the use of\\u000a microbial fuel cells, is considered as a new pathway for bioconversion\\u000a processes towards electricity. In comparison with conventional anaerobic\\u000a digestion, the microbial fuel cell technology holds some specific\\u000a advantages,

  19. An adaptive strategy to control anaerobic digesters for wastewater treatment

    SciTech Connect

    Monroy, O.; Alvarez-Ramirez, J.; Cuervo, F.; Femat, R. [Universidad Autonoma Metropolitana-Iztapalapa, Mexico City (Mexico)] [Universidad Autonoma Metropolitana-Iztapalapa, Mexico City (Mexico)

    1996-10-01

    The design and implementation of a new adaptive controller for anaerobic digesters is presented using a general nonlinear model and an uncertainties estimation scheme. The primary advantage of this controller over standard adaptive controllers is that biogas flow rate measurements are not required. The resulting controller is similar in form to standard adaptive controllers and can be tuned analogously. The adaptive control strategy has been implemented in a pilot-scale anaerobic digester showing good performance and robustness against changes in the feed load.

  20. Animal and industrial waste anaerobic digestion: USA status report

    SciTech Connect

    Lusk, P.D. [Resource Development Associates, Washington, DC (United States)

    1996-01-01

    Pollutants from unmanaged animal and bio-based industrial wastes can degrade the environment, and methane emitted from decomposing wastes may contribute to global climate change. One waste management system prevents pollution and converts a disposal problem into a new profit center. Case studies of operating systems indicate that the anaerobic digestion of animal and industrial wastes is a commercially available bioconversion technology with considerable potential for providing profitable coproducts, including a cost-effective renewable fuel. Growth and concentration of the livestock industry create opportunities to properly dispose of the large quantities of manures generated at dairy, swine, and poultry farms. Beyond the farm, extension of the anaerobic digestion process to recover methane has considerable potential for certain classified industries - with a waste stream characterization similar to livestock manures. More than 35 example industries have been identified, and include processors of chemicals, fiber, food, meat, milk, and pharmaceuticals. Some of these industries already recover methane for energy. This status report examines some current opportunities for recovering methane from the anaerobic digestion of animal and industrial wastes in the US. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned,{close_quotes} are included as a reality check. Factors necessary for successful projects, as well as a list of reasons explaining why some anaerobic digestion projects fail, are provided. The role of management is key; not only must digesters be well engineered and built with high-quality components, they must also be sited at facilities willing to incorporate the uncertainties of a new technology. Anaerobic digestion can provide monetary benefits and mitigate possible pollution problems, thereby sustaining development while maintaining environmental quality.

  1. Animal and industrial waste anaerobic digestion: USA status report

    SciTech Connect

    Lusk, P.D. [Resource Development Associates, Washington, DC (United States)

    1995-11-01

    Pollutants from unmanaged animal and bio-based industrial wastes can degrade the environment, and methane emitted from decomposing wastes may contribute to global climate change. One waste management system prevents pollution and converts a disposal problem into a new profit center. Case studies of operating systems indicate that the anaerobic digestion of animal and industrial wastes is a commercially available bioconversion technology with considerable potential for providing profitable coproducts, including a cost-effective renewable fuel. Growth and concentration of the livestock industry create opportunities to properly dispose of the large quantities of manures generated at dairy, swine, and poultry farms. Beyond the farm, extension of the anaerobic digestion process to recover methane has considerable potential for certain classified industries with a waste steam characterization similar to livestock manures. More than 35 example industries have been identified, and include processors of chemicals, fiber, food, meat, mil, and pharmaceuticals. Some of these industries already recover methane for energy. This status report examines some current opportunities for recovering methane from the anaerobic digestion of animal and industrial wastes in the U.S. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned,{close_quotes} are included as a reality check. Factors necessary for successful projects, as well as a list of reasons explaining why some anaerobic digestion projects fail, are provided. The role of management is key; not only must digesters be well engineered and built with high-quality components, they must also be sited at facilities willing to incorporate the uncertainties of a new technology. Anaerobic digestion can provide monetary benefits and mitigate possible pollution problems, thereby sustaining development while maintaining environmental quality.

  2. An environmental assessment of recovering methane from municipal solid waste by anaerobic digestion

    SciTech Connect

    O'Leary, P.R.

    1989-01-01

    The development of an experimental process which produces synthetic natural gas (SNG) or biogas by anaerobic digestion of municipal solid waste (MSW) is evaluated. This technology, if implemented, would be utilized in lieu of incineration or directly landfilling waste. An environmental assessment describing the principal impacts associated with operating the MSW anaerobic digestion process is presented. Variations in process configurations provide for SNG or electricity production and digester residue incineration, composting, or landfilling. Four process configuration are compared to the conventional solid waste disposal alternative of mass burn incineration and landfilling. Emissions are characterized, effluents quantified, and landfill areas predicted. The quantity of SNG and electricity recovered, and aluminum and ferrous metals recycled is predicted along with the emissions and effluents avoided by recovering energy and recycling metals. Air emissions are the primary on-site concern with the anaerobic digestion process. However, when compared to mass burn incineration, the projected particulate emissions for the anaerobic digestion process range from 2.9 {times} 10{sup {minus}6} to 2.6 {times} {sup 10{minus}5} pounds per ton of waste vs. 3.3 {times} 10{sup {minus}5} pounds per ton for mass burn. SO{sub 2}, NO{sub x}, and PCCD emissions have a similar relationship.

  3. Waste heat utilization in an anaerobic digestion system

    NASA Astrophysics Data System (ADS)

    Boissevain, Brett

    Anaerobic digestion has great potential as an energy source. Not only does it provide an effective method for waste mitigation, but it has the potential to generate significant quantities of fuel and electricity. In order to ensure efficient digestion and biomass utilization, however, the system must be continuously maintained at elevated temperatures. It is technically feasible to supplement such a system with outside energy, but it is more cost effective to heat the system using only the produced biogas. While there is considerable literature covering the theory of anaerobic digestion, there are very few practical studies to show how heat utilization affects system operation. This study considers the effect of major design variables (i.e. heat exchanger efficiencies and biogas conditioning) on promoting a completely self-sustaining digestion system. The thesis considers a real world system and analyzes how it can be improved to avoid the need of an external energy source.

  4. Labscale Evaluation of Biomass-Derived Elements Used in Anaerobic Digestion

    E-print Network

    Labscale Evaluation of Biomass-Derived Elements Used in Anaerobic Digestion This report presents performance data for an anaerobic digestion system (at a 10-liter scale) utilizing corncob biochar as biofilm support. The system operated on grease-trap wastewater and high-rate anaerobic digestion of this material

  5. Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes$

    E-print Network

    Paris-Sud XI, Université de

    Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes in simulation. Keywords: Anaerobic digestion, biotechnology, steady state analysis, $ This work was supported the phenomenologic behavior of anaerobic digestion systems following the idea that all the available information

  6. Video Article Continuously-Stirred Anaerobic Digester to Convert Organic Wastes into

    E-print Network

    Angenent, Lars T.

    Video Article Continuously-Stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System@cornell.edu URL: http://www.jove.com/video/3978/ DOI: 10.3791/3978 Keywords: Anaerobic Digestion, J.G., Spirito, C.M., Angenent, L.T. Continuously-Stirred Anaerobic Digester to Convert Organic

  7. The viscoelastic behaviour of raw and anaerobic digested sludge: strong similarities with soft-glassy materials

    E-print Network

    Paris-Sud XI, Université de

    1 The viscoelastic behaviour of raw and anaerobic digested sludge: strong similarities with soft be used to model the rheological behaviour of raw and anaerobic digested sludge. Keywords Glassy materials in pipes or in tanks and reactors, such as anaerobic digesters. However, sludge properties continuously

  8. Optimizing the anaerobic digestion of microalgae in a coupled Terence Bayen

    E-print Network

    Paris-Sud XI, Université de

    Optimizing the anaerobic digestion of microalgae in a coupled process Terence Bayen , Francis by light and an anaerobic digester. The mathematical model for the dynamics of the reactors takes for sustainable energy production [2]. Anaerobic digestion can be applied to recover the energy stored

  9. EVALUATION OF THE PERFORMANCE OF DIFFERENT ANAEROBIC DIGESTION TECHNOLOGIES FOR SOLID WASTE TREATMENT

    Microsoft Academic Search

    Mariana Chavez-Vazquez; David M. Bagley

    The anaerobic digestion of solid wastes is now a widely- used technology in Europe with more than 50 full- scale plants operating. However, anaerobic solid waste digestion is still used to only a limited extent in North America with only three facilities in Canada. Because of the expected importance of anaerobic digestion in the future for energy recovery, reliable tools

  10. Modified Anaerobic Digestion Model No.1 for dry and semi-dry anaerobic digestion of solid organic waste.

    PubMed

    Liotta, Flavia; Chatellier, Patrice; Esposito, Giovanni; Fabbricino, Massimiliano; Frunzo, Luigi; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco

    2015-04-01

    The role of total solids (TS) content in anaerobic digestion of selected complex organic matter, e.g. rice straw and food waste, was investigated. A range of TS from wet (4.5%) to dry (23%) was evaluated. A modified version of the Anaerobic Digestion Model No.1 for a complex organic substrate is proposed to take into account the effect of the TS content on anaerobic digestion. A linear function that correlates the kinetic constants of three specific processes (i.e. disintegration, acetate and propionate up-take) was included in the model. Results of biomethanation and volatile fatty acids production tests were used to calibrate the proposed model. Model simulations showed a good agreement between numerical and observed data. PMID:25311887

  11. Experimental digester facility modifications and digester gas upgrading research

    SciTech Connect

    Srivastava, V.J.; Biljetina, R.; Akin, C.

    1989-01-01

    The Institute of Gas Technology (IGT) has been participating in an experimental program at the Community Waste Research Facility (CWRF) located at the Walt Disney World Resort Complex, Orlando, Florida. Four institutions have formed a team to provide solutions to community waste treatment and disposal programs. Of primary importance to this research effort is the implementation of low-cost, energy-efficient waste treatment and recovery technologies and the net production of energy (methane) from biomass and waste resources. The production of methane is being studied in a novel, high-rate digester. During 1988, we were responsible for modifying the Experimental Test Unit (ETU) to permit dry solids feeding of refuse-derived fuel (RDF) and for conducting bench-scale experiments to evaluate techniques for efficient removal of carbon dioxide produced during anaerobic digestion.

  12. Single stage anaerobic digester at Tarleton State University. Final report

    SciTech Connect

    Not Available

    1980-01-01

    The design and operation of the demonstration plant facilities at Tarleton State University to produce methane in a single stage anaerobic digester are described. A combination of manures from hogs and poultry are used as feedstock. Uses for the methane, cost of the digester, and value of the energy produced are discussed. During the 21 months of operation, 310 people have visited the project. (DMC)

  13. Anaerobic sludge digestion in the presence of lactobacillus additive

    SciTech Connect

    Ghosh, S.; Klass, D.L.

    1980-01-01

    A laboratory evaluation of a lactobacillus fermentation product was performed to study its effects as an additive on the anaerobic digestion of sewage sludge under conventional and overloaded high-rate conditions. The overloaded conditions were those experienced in commercial municipal digesters. It was concluded from this work that the use of the additive at low concentrations permits digester operation at least up to double the loading of untreated digesters and at higher methane yields and volatile solids reductions without affecting effluent quality. The additive also imparts iproved digester stability and rapid response to loading rate and detention time excursions and upsets. The beneficial effets of the additive observed in the laboratory remain to be established with other feeds such as biomass, and in large-scale commercial digestion tests that are now in progress.

  14. Comparison between ozone and ultrasound disintegration on sludge anaerobic digestion.

    PubMed

    Braguglia, C M; Gianico, A; Mininni, G

    2012-03-01

    This paper deals with the comparison of ultrasound (mechanical) and ozone (chemical) pre-treatment on the performances of excess sludge semi-continuous digestion. Sludge solubilisation has been investigated by varying specific energy input. For each pre-treatment, long anaerobic digestion tests were carried out by two parallel digesters: one reactor, as control unit, was fed with untreated waste activated sludge, and the other one was fed with disintegrated sludge. To evaluate and compare the efficacy of both pre-treatments, the specific energy was maintained approximately the same. The digestion tests were carried out to investigate the feasibility of anaerobic digestion performance (total biogas production, volatile solids removal, sludge dewaterability) and to assess the heat balance. Results obtained from the digestion of sonicated sludge at 4% disintegration degree (? 2500 kJ/kg TS) showed that the ultrasound pre-treatment may be effective both in increasing VS destruction (+19%) and cumulative biogas production (+26%). On the contrary, the digestion test with ozonized sludge (ozone dose of 0.05 g O(3)/g TS corresponding to ? 2000 kJ/kg TS) did not indicate a significant improvement on the digestion performances. By doubling the ozone dose an improvement in the organics removal and cumulative biogas production was observed. Relevant differences in terms of colloidal charge and filterability were discussed. PMID:20719427

  15. Anaerobic digestion and wastewater treatment systems

    Microsoft Academic Search

    G. Lettinga

    1995-01-01

    Upflow Anaerobic Sludge Bed (UASB) wastewater (pre-)treatment systems represent a proven sustainable technology for a wide range of very different industrial effluents, including those containing toxic\\/inhibitory compounds. The process is also feasible for treatment of domestic wastewater with temperatures as low as 14–16° C and likely even lower. Compared to conventional aerobic treatment systems the anaerobic treatment process merely offers

  16. Biogas production from anaerobic digestion of Spirulina maxima algal biomass

    SciTech Connect

    Samson, R.; LeDuy, A.

    1982-08-01

    The photosynthetic spectrum of solar energy could be exploited for the production of chemical energy of methane through the combined algal-bacterial process. In this process, the algae are mass produced from light and from carbon in the first step. The algal biomass is then used as a nutrient for feeding the anaerobic digester, in the second step, for the production of methane by anaerobic bacteria. The carbon source for the production of algal biomass could be either organic carbon from wastewaters (for eucaryotic algae), or carbon dioxide from the atmosphere or from the combustion exhaust gases (for both prokaryotic and eukaryotic algae). The technical feasibility data on the anaerobic digestion of algal biomass have been reported for many species of algae including macroscopic algae and microscopic algae. Research being conducted in the authors' laboratory consists of using the semimicroscopic blue-green alga Spirulina maxima as the sole substrate for this combined algal-bacterial process. This species of alga is very attractive for the process because of its capability of using the atmospheric carbon dioxide as carbon source and its simple harvesting methods. Furthermore, it appeared that the fermentability of S. maxima is significantly higher than other microscopic algae. This communication presents the results on the anaerobic inoculum development by the adaptation technique. This inoculum was then used for the semicontinuous anaerobic digestion of S. maxima algal biomass. The evolutions of biogas production and composition, biogas yield, total volatile fatty acids, alkalinity, ammonia nitrogen, pH, and electrode potential were followed.

  17. Kinetic model for anaerobic digestion of biogas biological sludge

    SciTech Connect

    Pavlostathis, S.G.; Gossett, J.M.

    1986-10-01

    The principal objective of this study was the development and evaluation of a comprehensive kinetic model capable of predicting digester performance when fed biological sludge. Preliminary conversion mechanisms such as cell deaths, lysis, and hydrolysis responsible for rendering viable biological sludge organisms to available substrate were studied in depth. The results of this study indicate that hydrolysis of the dead, particulate biomass - primarily consisting of protein - is the slowest step, and therefore kinetically controls the overall process of an anaerobic digestion of biological sludge. A kinetic model was developed which could accurately describe digester performance and predict effluent quality.

  18. Thermophilic Anaerobic Digester Performance Under Different Feed-Loading Frequency

    NASA Astrophysics Data System (ADS)

    Bombardiere, John; Espinosa-Solares, Teodoro; Domaschko, Max; Chatfield, Mark

    The effect of feed-loading frequency on digester performance was studied on a thermophilic anaerobic digester with a working volume of 27.43 m3. The digester was fed 0.93 m3 of chicken-litter slurry/d, containing 50.9 g/L chemical oxygen demand. The treatments were loading frequencies of 1, 2, 6, and 12 times/d. The hourly pH, biogas production, and methane percent of the biogas were less stable at lower feed frequencies. There was no statistical difference among treatments in methanogenic activity. The feed-loading frequency of six times per day treatment provided the greatest biogas production.

  19. A STUDY OF LAND APPLICATION OF ANAEROBICALLY DIGESTED BIOSOLIDS

    EPA Science Inventory

    A field-scale research project was conducted in 2004-2005 to evaluate land application of anaerobically digested biosolids at agronomic levels. Biosolids had not been applied to this land previously. For this study, biosolids wee applied in a 100-m diameter circle by a side dis...

  20. Advanced control of anaerobic digestion processes through disturbances monitoring

    Microsoft Academic Search

    Jean-Philippe Steyer; Pierre Buffière; Damien Rolland; René Moletta

    1999-01-01

    This paper presents a new control strategy for highly loaded anaerobic digestion processes. This strategy is based on the analysis of disturbances added on purpose to the influent flow rate. The control system then carefully overlooks the response of only two parameters, the biogas output flow rate and the pH, in order to determine whether or not the load can

  1. STABILIZATION OF SEWAGE SLUDGE BY TWO-PHASE ANAEROBIC DIGESTION

    EPA Science Inventory

    The research described in the report was concerned with evaluation of alternative approaches to anaerobic digestion, a process commonly used on the residual stream from wastewater treatment. The principal approach studied was that of separating the acid- and methane-forming phase...

  2. Anaerobic digestion of biomass for methane production: A review

    Microsoft Academic Search

    V. Nallathambi Gunaseelan

    1997-01-01

    Biological conversion of biomass to methane has received increasing attention in recent years. Hand- and mechanically-sorted municipal solid waste and nearly 100 genera of fruit and vegetable solid wastes, leaves, grasses, woods, weeds, marine and freshwater biomass have been explored for their anaerobic digestion potential to methane. In this review, the extensive literature data have been tabulated and ranked under

  3. Controlled struvite crystallisation for removing phosphorus from anaerobic digester sidestreams

    Microsoft Academic Search

    Elisabeth V Münch; Keith Barr

    2001-01-01

    Enhanced biological phosphorus removal wastewater treatment plants that use anaerobic digesters for sludge treatment, have high phosphorus concentrations in the sidestreams from their sludge dewatering equipment. To remove phosphorus from such sidestreams controlled struvite crystallisation can be used. Struvite (or MAP) is a naturally occurring crystal of magnesium, ammonium and phosphate. We present operational results obtained with a continuously operated

  4. Anaerobic Digestion Analysis. Training Module 5.120.2.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with alkalinity, volatile acids and carbon dioxide determinations for an anaerobic sludge digester. Included are objectives, instructor guides, student handouts and transparency masters. This module considers total and bicarbonate…

  5. Anaerobic Digestion. Instructor's Guide. Biological Treatment Process Control.

    ERIC Educational Resources Information Center

    Carnegie, John W., Ed.

    This instructor's guide contains materials needed to teach a four-lesson unit on anaerobic digestion control. These materials include: (1) unit overview; (2) lesson plans; (3) lecture outlines; (4) student worksheets for each lesson (with answers); and (5) two copies of a final quiz (with and without answers). Lesson 1 is a review of the theory of…

  6. Anaerobic Digestion I. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.

    ERIC Educational Resources Information Center

    Arasmith, E. E.

    This lesson is the first of a two-part series on anaerobic digestion. Topics discussed include the five basic functions of an anaerobic digester, basic theory of the biological processes involved, basic equipment necessary for digestion, and the products of digestion. The lesson includes an instructor's guide and student workbook. The instructor's…

  7. Anaerobic co-digestion of livestock and vegetable processing wastes: fibre degradation and digestate stability.

    PubMed

    Molinuevo-Salces, Beatriz; Gómez, Xiomar; Morán, Antonio; García-González, Mari Cruz

    2013-06-01

    Anaerobic digestion of livestock wastes (swine manure (SM) and poultry litter (PL)) and vegetable processing wastes (VPW) mixtures was evaluated in terms of methane yield, volatile solids removal and lignocellulosic material degradation. Batch experiments were performed with 2% VS (volatile solids) to ensure complete conversion of TVFAs (total volatile fatty acids) and to avoid ammonia inhibition. Experimental methane yields obtained for the mixtures resulted in higher values than those obtained from the sum of the methane yields from the individual components. VPW addition to livestock wastes before anaerobic digestion also resulted in improved VS elimination. In SM-VPW co-digestions, CH4 yield increased from 111 to 244 mL CH4 g VS added(-1), and the percentage of VS removed increased from 50% to 86%. For PL-VPW co-digestions, the corresponding values were increased from 158 to 223 mL CH4 g VS added(-1) and from 70% to 92% VS removed. Hemicelluloses and more than 50% of cellulose were degraded during anaerobic digestion. Thermal analyses indicated that the stabilization of the wastes during anaerobic digestion resulted in significantly less energy being released by digestate samples than fresh samples. PMID:23540357

  8. Inactivation of Selected Bacterial Pathogens in Dairy Cattle Manure by Mesophilic Anaerobic Digestion (Balloon Type Digester)

    PubMed Central

    Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Okoh, Anthony I.; Makaka, Golden; Simon, Michael

    2014-01-01

    Anaerobic digestion of animal manure in biogas digesters has shown promise as a technology in reducing the microbial load to safe and recommended levels. We sought to treat dairy manure obtained from the Fort Hare Dairy Farm by investigating the survival rates of bacterial pathogens, through a total viable plate count method, before, during and after mesophilic anaerobic digestion. Different microbiological media were inoculated with different serial dilutions of manure samples that were withdrawn from the biogas digester at 3, 7 and 14 day intervals to determine the viable cells. Data obtained indicated that the pathogens of public health importance were 90%–99% reduced in the order: Campylobacter sp. (18 days) < Escherichia coli sp. (62 days) < Salmonella sp. (133 days) from a viable count of 10.1 × 103, 3.6 × 105, 7.4 × 103 to concentrations below the detection limit (DL = 102 cfu/g manure), respectively. This disparity in survival rates may be influenced by the inherent characteristics of these bacteria, available nutrients as well as the stages of the anaerobic digestion process. In addition, the highest p-value i.e., 0.957 for E. coli showed the statistical significance of its model and the strongest correlation between its reductions with days of digestion. In conclusion, the results demonstrated that the specific bacterial pathogens in manure can be considerably reduced through anaerobic digestion after 133 days. PMID:25026086

  9. Anaerobic digestion of microalgal biomass after ultrasound pretreatment.

    PubMed

    Passos, Fabiana; Astals, Sergi; Ferrer, Ivet

    2014-11-01

    High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16-67 MJ/kg TS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16-100%), hydrolysis rate (25-56%) and methane yield (6-33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS). PMID:25002372

  10. Factors controlling pathogen destruction during anaerobic digestion of biowastes

    SciTech Connect

    Smith, S.R. [Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)]. E-mail: s.r.smith@imperial.ac.uk; Lang, N.L. [Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Cheung, K.H.M. [Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Spanoudaki, K. [Centre for Environmental Control and Waste Management, Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2005-07-01

    Anaerobic digestion is the principal method of stabilising biosolids from urban wastewater treatment in the UK, and it also has application for the treatment of other types of biowaste. Increasing awareness of the potential risks to human and animal health from environmental sources of pathogens has focused attention on the efficacy of waste treatment processes at destroying pathogenic microorganisms in biowastes recycled to agricultural land. The degree of disinfection achieved by a particular anaerobic digester is influenced by a variety of interacting operational variables and conditions, which can often deviate from the ideal. Experimental investigations demonstrate that Escherichia coli and Salmonella spp. are not damaged by mesophilic temperatures, whereas rapid inactivation occurs by thermophilic digestion. A hydraulic, biokinetic and thermodynamic model of pathogen inactivation during anaerobic digestion showed that a 2 log{sub 10} reduction in E. coli (the minimum removal required for agricultural use of conventionally treated biosolids) is likely to challenge most conventional mesophilic digesters, unless strict maintenance and management practices are adopted to minimise dead zones and by-pass flow. Efficient mixing and organic matter stabilisation are the main factors controlling the rate of inactivation under mesophilic conditions and not a direct effect of temperature per se on pathogenic organisms.

  11. Early warning indicators for monitoring the process failure of anaerobic digestion system of food waste.

    PubMed

    Li, Lei; He, Qingming; Wei, Yunmei; He, Qin; Peng, Xuya

    2014-11-01

    To determine reliable state parameters which could be used as early warning indicators of process failure due to the acidification of anaerobic digestion of food waste, three mesophilic anaerobic digesters of food waste with different operation conditions were investigated. Such parameters as gas production, methane content, pH, concentrations of volatile fatty acid (VFA), alkalinity and their combined indicators were evaluated. Results revealed that operation conditions significantly affect the responses of parameters and thus the optimal early warning indicators of each reactor differ from each other. None of the single indicators was universally valid for all the systems. The universally valid indicators should combine several parameters to supply complementary information. A combination of total VFA, the ratio of VFA to total alkalinity (VFA/TA) and the ratio of bicarbonate alkalinity to total alkalinity (BA/TA) can reflect the metabolism of the digesting system and realize rapid and effective early warning. PMID:25218457

  12. Thermophilic two-stage dry anaerobic digestion of model garbage with ammonia stripping.

    PubMed

    Yabu, Hironori; Sakai, Chikako; Fujiwara, Tomoko; Nishio, Naomichi; Nakashimada, Yutaka

    2011-03-01

    To avoid the inhibition of methane production by ammonia that occurs during the degradation of garbage, anaerobic digestion with prior ammonia production and subsequent stripping was investigated. In the ammonia production phase, the maximum ammonia concentration was approximately 2800 mg N/kg of total wet sludge in the range of 4 days of sludge retention time, indicating that only 43% of total nitrogen in the model garbage was converted to ammonia. The model garbage from which ammonia was produced and stripped was subjected to semi-continuous thermophilic dry anaerobic digestion over 180 days. The gas yield was in the range of 0.68 to 0.75 Nm(3)/kg volatile solid, and it decreased with the decrease of the sludge retention time. The ammonia-nitrogen concentration in the sludge was kept below 3000 mg N/kg total wet sludge. Microbial community structure analysis revealed that the phylum Firmicutes dominated in the ammonia production, but the community structure changed at different sludge retention times. In dry anaerobic digestion, the dominant bacteria shifted from the phylum Thermotogae to Firmicutes. The dominant archaeon was the genus Methanothermobacter, but the ratio of Methanosarcina increased during the process of dry anaerobic digestion. PMID:21094085

  13. Anaerobic digestion of stillage to produce bioenergy in the sugarcane-to-ethanol industry.

    PubMed

    Fuess, Lucas Tadeu; Garcia, Marcelo Loureiro

    2014-01-01

    Stillage is the main wastewater from ethanol production, containing a high chemical oxygen demand in addition to acidic and corrosive characteristics. Though stillage may be used as a soil fertilizer, its land application may be considered problematic due its high polluting potential. Anaerobic digestion represents an effective alternative treatment to reduce the pollution load of stillage. In addition, the methane gas produced within the process may be converted to energy, which can be directly applied to the treatment plant. The objective of this paper was to investigate the energetic potential of anaerobic digestion applied to stillage in the sugarcane ethanol industry. An overall analysis of the results indicates energy recovery capacity (ERC) values for methane ranging from 3.5% to 10%, respectively, for sugarcane juice and molasses. The processes employed to obtain the fermentable broth, as well as the distillation step, represent the main limiting factors to the energetic potential feasibility. Considering financial aspects the annual savings could reach up to US$ 30 million due to anaerobic digestion of stillage in relatively large-scale distilleries (365,000 m3 of ethanol per year). The best scenarios were verified for the association between anaerobic digestion of stillage and combustion of bagasse. In this case, the fossil fuels consumption in distilleries could be fully ceased, such the ERC of methane could reach values ranging from 140% to 890%. PMID:24600872

  14. Discussion of ``The anaerobic digestion of organic waste``

    SciTech Connect

    NONE

    1996-12-31

    With respect to economics, the presenter indicated that anaerobic digestion of municipal solid waste (MSW) may not be economical based on the value of the energy produced. This will most likely be the case, partly because of the low energy prices in this country. These facilities would have to rely on tipping fees paid for receiving and processing the waste. As stated earlier, the high solids process will help improve the economics. While there are said to be 20 plants operating in Europe on MSW, there seems to be none in the US, and that is the condition this paper addresses. It was hoped that by exploring the benefits of co-digestion and stimulation, and showing how digestible certain components of MSW can be, more operators of existing anaerobic facilities would consider expanding their operations to include at least some elements of MSW.

  15. Methane production from and beneficiation of anaerobic digestion of aquatic plant material

    SciTech Connect

    Klass, D.L.; Ghosh, S.

    1984-01-03

    A process is disclosed for improved CH/sub 4/ production by anaerobic digestion of aquatic plant material, at least a portion or all which was grown in organically polluted water. Mixtures of aquatic plant material whose 1 portion was grown in nonpolluted and a 2nd portion comprising approximately 10 wt.% or more grown in organically polluted water can be used. The liquid effluent from the digester may be advantageously returned to the aquatic plant-growing pond to maintain the desired organic pollution. The process provides for improved CH/sub 4/ production from aquatic plant material which is, by itself, recalcitrant to anaerobic digestion. Thus, 2 digesters were operated under the same conditions, the 1st being fed with water hyacinth grown in nonorganic polluted hardwater of BOD 5 mg/l and hardness of 20 grains/gal. and the 2nd being fed with water hyacinth grown in sewage-polluted water of BOD 20 mg/l. Each digester was operated in a semicontinuous completely mixed anaerobic manner with a culture volume of 5 liters for a detention time of 12 days, a loading of 0.1 lb volatile solid/cubic feet-day, and 35/sup 0/ at pH of 6.8-7.1. The runs were contained for several detention times and exhibited stable performance. CH/sub 4/ yield increased approximately 69% and the gas-production rate increased approximately 82% by using water hyacinth feed grown in sewage-polluted water.

  16. Anaerobic digestion for energy production and environmental protection

    SciTech Connect

    Lettinga, G. [Agricultural Univ., Wageningen (Netherlands); Haandel, A.C. Vaan [Federal Univ. of Paraiba, Campina Grande (Brazil)

    1993-12-31

    Anaerobic digestion is the decomposition of complex molecules into simpler substances by micro-organisms in the absence of oxygen. Anaerobic digestion processes can be employed for resource conservation, for the production of biogas and other useful end products from biomass, and for environmental protection through waste and wastewater treatment. Modern high-rate anaerobic wastewater-treatment processes can effectively remove organic pollutants from wastewater at a cost far below that of conventional aerobic processes. These anaerobic wastewater treatment processes can also be profitably applied for the generation of biogas from energy crops such as sugarcane. In fact, these methods might even be an attractive alternative for the alcohol fermentation extensively employed in Brazil for the production of fuel alcohol from sugarcane. The potential of modern anaerobic processes for this purpose has not yet been widely recognized. This paper describes the principles and use of these processes and demonstrates their prospects for producing energy from sugarcane (1) by treating vinasse, the wastewater generated during the production of ethanol from sugarcane, and (2) as a direct method for producing biogas from sugarcane juice.

  17. Novel trends in anaerobic digestion of municipal solid waste.

    PubMed

    De Baere, Luc

    2003-01-01

    Anaerobic digestion capacity has been installed on a large scale for the treatment of biowaste coming from municipal solid waste in the 90's. However, in recent years, a new trend has developed in which anaerobic digestion is applied more and more for the treatment of mixed or grey waste. It is expected that the installed capacity for grey/mixed waste will surpass the capacity installed for biowaste digestion. Five years ago, more than 85% of the treatment capacity was for biowaste digestion and only 15% for grey/mired waste digestion, derived from two old plants that were constructed prior to 1990. By the end of 2004, a digestion capacity of 1,285,000 ton per year will be available in Europe for the treatment of grey or mixed MSW, while digestion capacity for biowaste will only amount to 1,270,000 ton per year. Especially dry digestion offers new perspectives. Dry digestion is particularly suited for the treatment of grey/mixed waste due to its insensitivity to the presence of heavy inerts and light materials. Heavy inerts such as sand, glass and stones cause sedimentation and the light materials cause floatation and scum formation in the more conventional wet and semi-dry systems. Due to the high initial dry solids content, the digestate coming from dry digestion can be treated in a variety of ways. Besides the conventional mechanical dewatering, drying with waste heat or aerobic drying by addition of a fresh waste can be utilized for the production of a high-quality compost in case of the treatment of biowaste. Digestate from mixed or grey waste is not immediately suitable for the production of a high-quality compost. However, integration with incineration plants and landfills can be optimized easily with such a dry digestate and offers various interesting alternatives. In case a maximum of recyclables is pursued, the dry digestion can be followed by a wet separation in order to produce marketable endproducts such as sand and fibers. PMID:15296145

  18. Anaerobic digestion of pulp and paper mill wastewater and sludge.

    PubMed

    Meyer, Torsten; Edwards, Elizabeth A

    2014-11-15

    Pulp and paper mills generate large amounts of waste organic matter that may be converted to renewable energy in form of methane. The anaerobic treatment of mill wastewater is widely accepted however, usually only applied to few selected streams. Chemical oxygen demand (COD) removal rates in full-scale reactors range between 30 and 90%, and methane yields are 0.30-0.40 m(3) kg(-1) COD removed. Highest COD removal rates are achieved with condensate streams from chemical pulping (75-90%) and paper mill effluents (60-80%). Numerous laboratory and pilot-scale studies have shown that, contrary to common perception, most other mill effluents are also to some extent anaerobically treatable. Even for difficult-to-digest streams such as bleaching effluents COD removal rates range between 15 and 90%, depending on the extent of dilution prior to anaerobic treatment, and the applied experimental setting. Co-digestion of different streams containing diverse substrate can level out and diminish toxicity, and may lead to a more robust microbial community. Furthermore, the microbial population has the ability to become acclimated and adapted to adverse conditions. Stress situations such as toxic shock loads or temporary organic overloading may be tolerated by an adapted community, whereas they could lead to process disturbance with an un-adapted community. Therefore, anaerobic treatment of wastewater containing elevated levels of inhibitors or toxicants should be initiated by an acclimation/adaptation period that can last between a few weeks and several months. In order to gain more insight into the underlying processes of microbial acclimation/adaptation and co-digestion, future research should focus on the relationship between wastewater composition, reactor operation and microbial community dynamics. The potential for engineering and managing the microbial resource is still largely untapped. Unlike in wastewater treatment, anaerobic digestion of mill biosludge (waste activated sludge) and primary sludge is still in its infancy. Current research is mainly focused on developing efficient pretreatment methods that enable fast hydrolysis of complex organic matter, shorter sludge residence times and as a consequence, smaller sludge digesters. Previous experimental studies indicate that the anaerobic digestibility of non-pretreated biosludge from pulp and paper mills varies widely, with volatile solids (VS) removal rates of 21-55% and specific methane yields ranging between 40 and 200 mL g(-1) VS fed. Pretreatment can increase the digestibility to some extent, however in almost all reported cases, the specific methane yield of pretreated biosludge did not exceed 200 mL g(-1) VS fed. Increases in specific methane yield mostly range between 0 and 90% compared to non-pretreated biosludge, whereas larger improvements were usually achieved with more difficult-to-digest biosludge. Thermal treatment and microwave treatment are two of the more effective methods. The heat required for the elevated temperatures applied in both methods may be provided from surplus heat that is often available at pulp and paper mills. Given the large variability in specific methane yield of non-pretreated biosludge, future research should focus on the links between anaerobic digestibility and sludge properties. Research should also involve mill-derived primary sludge. Although biosludge has been the main target in previous studies, primary sludge often constitutes the bulk of mill-generated sludge, and co-digestion of a mixture between both types of sludge may become practical. The few laboratory studies that have included mill primary sludge indicate that, similar to biosludge, the digestibility can range widely. Long-term studies should be conducted to explore the potential of microbial adaptation to lignocellulosic material which can constitute more than half of the organic matter in pulp and paper mill sludge. PMID:25150519

  19. Batch load anaerobic digestion of dairy manure 

    E-print Network

    Egg, Richard P

    1979-01-01

    removed versus influent total solids concentration. . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 31 Volatile solids reduction versus influent total solids concentration. . . . . ~ . . . . . . , . . ~ . . . . . 7 ~ COD reduction versus influent total solids concentration.... ~ ~ . . . . . . . . . . . . ~ ~ . . . . o. . . . . . ~ ~ ~ . ~ . 35 Volume of methane per mass of COD removed versus influent total solids concentration. . . . ~ 36 Cumulative biogas production versus time in batch cycle for laboratory digester run 3. . . , , , 40 10 ' Nass...

  20. Anaerobic digestion of livestock manures: A current opportunities casebook

    SciTech Connect

    Lusk, P.D.

    1995-08-01

    Growth and concentration of the livestock industry creates new opportunities for proper disposal of the large quantities of manures generated at dairy, swine, and poultry farms. One manure management system provides not only pollution prevention but also converts a problem into a new profit center. Economic evaluations and case studies of operating systems indicate that the anaerobic digestion of livestock manures is a commercially-available bioconversion technology with considerable potential for providing profitable co-products, including a renewable fuel. An introduction to the engineering economies of these technologies is provided, based on estimates of digesters that generate electricity from the recovered methane. Regression models used to estimate digester cost and internal rate of return are developed from the evaluations. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned{close_quotes}, are provided as a reality check.

  1. Integrated chemical–physical processes modelling—II. simulating aeration treatment of anaerobic digester supernatants

    Microsoft Academic Search

    E. V. Musvoto; M. C. Wentzel; G. A. Ekama

    2000-01-01

    A three phase (aqueous\\/solid\\/gas) mixed weak acid\\/base kinetic model is developed to simulate the physical and chemical processes that occur on aeration of anaerobic digester supernatant. Included in the model are the kinetic reactions for (i) weak acid\\/base dissociations (water, carbonate, ammonium, phosphate, and short-chain fatty acids), (ii) precipitation of struvite, newberyite, amorphous calcium phosphate, calcium and magnesium carbonate and

  2. Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion

    Microsoft Academic Search

    Tatsuya Noike; Ginro Endo; Juu-En Chang; Jun-Ichi Yaguchi; Jun-Ichiro Matsumoto

    1985-01-01

    The characteristics of the degradation of cellulose, soluble starch, and glucose in the acidogenic phase and the effects of the substrate loading rate and biological solids retention time on the methanogenic phase of anaerobic digestion were investigated. The results obtained from continuous experiments using laboratory-scale anaerobic chemostat reactors elucidated the true rate-limiting step of anaerobic digestion. The specific rate of

  3. Anaerobic waste-activated sludge digestion - A bioconversion mechanism and kinetic model

    Microsoft Academic Search

    Tatsuo Shimizu; Kenzo Kudo; Yoshikazu Nasu

    1993-01-01

    The anaerobic bioconversion of raw and mechanically lysed waste-activated sludge was kinetically investigated. The hydrolysis of the biopolymers, such as protein, which leaked out from the biological sludge with ultrasonic lysis, was a first-order reaction in anaerobic digestion and the rate constant was much higher than the decay rate constant of the raw waste activated sludge. An anaerobic digestion model

  4. Anaerobic digestion of livestock manures in the USA: A current opportunities casebook

    SciTech Connect

    Lusk, P.D. [Resource Development Associates, Washington, DC (United States)

    1994-12-31

    Growth and concentration of the livestock industry creates opportunities for the proper disposal of the large quantities of manures generated at dairy, swine and poultry farms. One manure management system provides not only pollution prevention but also converts a manure management problem into a new profit center. Economic evaluations and case studies of operating systems indicate that the anaerobic digestion of livestock manures is a commercially-available bioconversion technology with considerable potential for providing profitable co-products including a cost-effective alternative fuel for livestock production operations. This Casebook examines some of the current opportunities for the recovery of methane from the anaerobic digestion of animal manures. An introduction to the engineering economies of these technologies is provided and possible end-use applications for methane gas generated by the digestion process are discussed. The economic evaluations are based on engineering studies of digesters that generate electricity from the recovered methane. Regression models, which can be used to estimate digester cost and internal rate of return, are developed from the evaluations. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned{close_quotes}, are provided as a reality check.

  5. Conversion of carbohydrates in herbaceous crops during anaerobic digestion.

    PubMed

    Pakarinen, Annukka; Kymalainen, Maritta; Stoddard, Frederick L; Viikari, Liisa

    2012-08-15

    The methane yields and conversion of pentoses (xylose) and hexoses (cellulose) in hemp, maize, and white lupin were studied over 30 days of anaerobic digestion. Preservation of hemp increased the methane yield by 23% compared with the fresh hemp. The increased methane yield of hemp was verified by the enhanced conversion of C6 sugars, increasing from 48% to about 70%, whereas the conversion of C5 sugars increased from only 9% to nearly 50%. The consumption of all carbohydrates in fresh maize was almost complete in the 30 days of anaerobic digestion. Hence, there was no major difference in carbohydrate consumption between fresh and preserved maize during biogas production. Fresh white lupin produced the highest methane yield (343 ± 33 dm(3) kg(-1) TS) in this work, mainly due to its highest amount of proteins. Conversion of C6 sugars was 80%, but that of C5 sugars was notably less at 46%. PMID:22788699

  6. Reduction of Antibiotic-Resistant Bacteria Present in Food Animal Manures by Composting and Anaerobic Digestion

    E-print Network

    Jones, Michelle

    and Anaerobic Digestion Frederick C. Michel, Food, Agricultural, and Biological Engineering Zhongtang Yu, Animal digestion and composting at mesophilic or moderate temperature significantly reduced the antimicrobial concluded that both anaerobic digestion and composting--especially at elevated temperatures--are effective

  7. Energy and economic assessment of anaerobic digesters and biofuels for rural waste management

    Microsoft Academic Search

    T. P. Abeles; D. F. Freedman; L. A. DeBaere; D. A. Ellsworth

    1978-01-01

    A technological and socioeconomic assessment of anaerobic digester feasibility for small to mid-size livestock operations was undertaken. Three full scale digesters and one pilot scale facility were under various degrees of monitoring and evaluation to assess design and operational problems as they affect the adoption and establishment of farm scale anaerobic digesters. Materials handling presented the greatest obstacle to satisfactory

  8. The Effect of Enzyme Addition on Anaerobic Digestion of Jose Tall Wheat Grass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of the addition of enzyme products containing cellulase, hemicellulase, and Beta-glucosidase to anaerobic digestion systems were studied. Anaerobic digestion tests were performed using batch reactors operated at 35°C. The application of enzyme products in three digestion configurations w...

  9. Anaerobic digestion of two biodegradable municipal waste streams.

    PubMed

    Zhang, Yue; Banks, Charles J; Heaven, Sonia

    2012-08-15

    Landfill avoidance for organic wastes is now a high priority worldwide. Two fractions of the municipal waste stream were considered with respect to their potential for diversion through controlled anaerobic digestion. The physical and chemical properties of source segregated domestic food waste (ss-FW) and of the mechanically-recovered organic fraction of municipal solid waste (mr-OFMSW) were analysed, and their methane yields determined in both batch and semi-continuous digestion. Methane potentials were compared with predicted values based on biochemical composition, elemental analysis and carbon mass balance, and the differences explained by compositional analysis of feedstocks and digestates. The ss-FW had a higher percentage biodegradability and higher energy potential on a dry weight basis due to the high proportion of proteins and fats in this waste, although the energy potential of the mr-OFMSW was slightly higher on a wet weight (WW) basis. The mr-OFMSW showed very stable digestion characteristics, whereas the ss-FW had a high digestate ammoniacal-N concentration and volatile fatty acid accumulation leading to some process instability. Digestates from semi-continuous trials with mr-OFMSW had high concentrations of potentially toxic elements (PTE) and a lower nutrient content than ss-FW digestate, making the former unsuitable for application to land used in food production. PMID:22504715

  10. Anaerobic Digestion for Mitigation of Biodiesel Production Byproducts

    NSDL National Science Digital Library

    The Advanced Technology Environmental and Energy Center (ATEEC) provides this document, which was part of a workshop held on anaerobic digestion for mitigation of biodiesel production byproducts. It would be useful for instructors looking to develop their own curriculum on biofuels and biodiesel byproducts. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

  11. Metabolic activity of pathogenic bacteria during semicontinuous anaerobic digestion.

    PubMed Central

    Kearney, T E; Larkin, M J; Levett, P N

    1994-01-01

    In natural environments such as anaerobic digesters, bacteria are frequently subjected to the stress of nutrient fluxes because of the continual changes in the flow of nutrients, and to survive, they must be capable of adapting readily to nutrient changes. In this study, the metabolic activities of Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes, and Campylobacter jejuni were studied within culture bags (Versapor-200 filters, 0.22-microns pore size) in laboratory anaerobic digesters. The metabolic activity of these bacteria was indicated by their adenylate energy charge (EC) ratios and their ability to incorporate [3H]thymidine, which was related to the respective changes in viable numbers within the culture bags during anaerobic digestion. Fluctuations in the adenylate EC ratios, the uptake of [3H]thymidine, and the viable numbers of E. coli, S. typhimurium, Y. enterocolitica, and L. monocytogenes cells were probably due to constant changes in the amount of available nutrients within the anaerobic digesters. The viability of S. typhimurium increased quickly after a fresh supply of nutrients was added to the system as indicated by the uptake of [3H]thymidine and an increase in the adenylate EC ratios. The viable numbers of E. coli, S. typhimurium, Y. enterocolitica, and L. monocytogenes organisms declined rapidly from 10(7) to 10(8) CFU/ml to 10(3) to 10(4) CFU/ml and remained at this level for an indefinite period. The decimal reduction time calculated during the period of exponential decline ranged from 0.8 to 1.2 days for these bacteria. C. jejuni had the greatest mean decimal reduction time value (3.6 days).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7986040

  12. Production of Methane Biogas as Fuel Through Anaerobic Digestion

    Microsoft Academic Search

    Zhongtang Yu; Floyd L. Schanbacher

    \\u000a Anaerobic digestion (AD) is a biotechnology by which biomass is converted by microbes to methane (CH4) biogas, which can then be utilized as a renewable fuel to generate heat and electricity. A genetically and metabolically\\u000a diverse community of microbes (mainly bacteria and methanogens) drives the AD process through a series of complex microbiological\\u000a processes in the absence of oxygen. During

  13. Mechanical pretreatment of waste activated sludge for anaerobic digestion process

    Microsoft Academic Search

    In Wook Nah; Yun Whan Kang; Kyung-Yub Hwang; Woong-Ki Song

    2000-01-01

    This research investigated the effect of mechanical pretreatment of waste activated sludge (WAS) to a pilot scale (2000 l) anaerobic digestion process. Mechanical pretreatment of WAS by jetting and colliding to a collision-plate at 30 bar made the sludge solubilized, as examining some parameters before and after mechanical pretreatment of waste-activated sludge; for example, Suspended Solid (SS), Soluble Chemical Oxygen Demand

  14. Relating methanogen community structure and anaerobic digester function.

    PubMed

    Bocher, B T W; Cherukuri, K; Maki, J S; Johnson, M; Zitomer, D H

    2015-03-01

    Much remains unknown about the relationships between microbial community structure and anaerobic digester function. However, knowledge of links between community structure and function, such as specific methanogenic activity (SMA) and COD removal rate, are valuable to improve anaerobic bioprocesses. In this work, quantitative structure-activity relationships (QSARs) were developed using multiple linear regression (MLR) to predict SMA using methanogen community structure descriptors for 49 cultures. Community descriptors were DGGE demeaned standardized band intensities for amplicons of a methanogen functional gene (mcrA). First, predictive accuracy of MLR QSARs was assessed using cross validation with training (n = 30) and test sets (n = 19) for glucose and propionate SMA data. MLR equations correlating band intensities and SMA demonstrated good predictability for glucose (q(2) = 0.54) and propionate (q(2) = 0.53). Subsequently, data from all 49 cultures were used to develop QSARs to predict SMA values. Higher intensities of two bands were correlated with higher SMA values; high abundance of methanogens associated with these two bands should be encouraged to attain high SMA values. QSARs are helpful tools to identify key microorganisms or to study and improve many bioprocesses. Development of new, more robust QSARs is encouraged for anaerobic digestion or other bioprocesses, including nitrification, nitritation, denitrification, anaerobic ammonium oxidation, and enhanced biological phosphorus removal. PMID:25562581

  15. Dissolved hydrogen concentration as an on-line control parameter for the automated operation and optimization of anaerobic digesters

    SciTech Connect

    Cord-Ruwisch, R.; Mercz, T.I.; Hoh, C.Y.; Strong, G.E. [Murdoch Univ., Perth (Australia). School of Biological and Environmental Sciences] [Murdoch Univ., Perth (Australia). School of Biological and Environmental Sciences

    1997-12-20

    The stability and efficiency of the industrial anaerobic digestion process relies upon the balance between the degradation of organic waste to hydrogen, formate, acetate, and C{sub 3} to C{sub 5} volatile fatty acids (VFAs) and the conversion of these fermentation products to methane and carbon dioxide. The use of dissolved hydrogen as an early warning signal of digester failure and a control parameter to operate anaerobic digesters was investigated. A sensitive, on-line method was developed for measuring trace levels of dissolved hydrogen in a semi-permeable membrane, situated within the biomass of a 1 L laboratory anaerobic digester, using trace reduction gas analysis. At normal operating conditions, the dissolved hydrogen partial pressure (2 to 8 Pa) was found to be linearly correlated with the loading rate of the digester, and was a sensitive indicator of the effect of shockloads as well as gradual overloading. An increase in hydrogen partial pressure above a critical concentration of 6.5--7 Pa indicated the initial stage of digester overloading. A H{sub 2}-based computer control system, using a critical hydrogen partial pressure of 6.5 Pa as the setpoint, was found to be effective for the safe operation of a laboratory digester close to its maximum sustainable loading rate. The existence of a relationship between hydrogen level and organic loading rate was also confirmed on a 600 m{sup 3} industrial digester, with digester overloading occurring at hydrogen concentrations above 7 Pa.

  16. Liquid-liquid extraction of short-chain organic acids from anaerobic digesters

    SciTech Connect

    Wene, E.G.; Antonopoulos, A.A.

    1989-01-01

    Anaerobic digesters with glucose or municipal solid waste (MSW) feed were operated to maximize production of short-chain organic acids. Digester effluent was extracted by liquid-liquid extraction with trioctylphosphine oxide (TOPO) or trioctylamine (TOA) in heptane or 2-heptanone as the water immiscible phase. Digester effluent was recycled to digesters after extraction. Both TOPO and TOA in organic solvents effectively extract organic acids from anaerobic digester fluid. Longer chain acids have a higher distribution coefficient than shorter-chain acids. Long term extraction of digester fluid with recycle was not toxic to the anaerobic production of short-chain acids.

  17. Micro-scale anaerobic digestion of point source components of organic fraction of municipal solid waste

    E-print Network

    Columbia University

    Micro-scale anaerobic digestion of point source components of organic fraction of municipal solid that are needed when designing plug-flow type anaerobic bioreactors. More specifically, the decomposition patterns

  18. Feasibility assessment of anaerobic digestion of European water chestnuts (Trapa natans L. )

    SciTech Connect

    Besha, J.A.; Countryman, W.D.

    1980-07-01

    The project determined the technical and economic feasibility of anaerobic digestion of Trapa natans L. or European water chestnuts, to produce methane. Trapa natans is a nuisance aquatic plant presently found in the northeastern United States. The field data collection phase included color aerial photogrammetry and manual sampling. Yields of 9.08 kg per square meter of raw material with a corresponding dry weight of 1.53 kg/sq meter were determined. Bacterial digestion resulting in gas production of 69% methane and 31% carbon dioxide was shown in laboratory-scale digestion experiments. Mass spectrographic analysis indicated no contaminants in the gas stream. Conceptual technical design of a 400 kW methane-fueled electric generation facility indicated economic feasibility of this facility either as an independent or a hybrid process in conjunction with a small hydroelectric facility. Substantial economic and environmental benefits may accure from the control of Trapa natans by this means.

  19. Methane production by anaerobic digestion of water hyacinth (Eichhornia crassipes)

    SciTech Connect

    Klass, D.L.; Ghosh, S.

    1980-01-01

    Water hyacinth under conventional high-rate digestion conditions exhibited higher CH4 yields and energy recovery efficiencies when grown in sewage-fed lagoons than when grown in a fresh water pond. Mesophilic digestion provided the highest recovery of feed energy in the product gas as CH4, while thermophilic digestion, when operated at sufficiently high loading rates and reduced detention times, gave the highest specific CH4 production rates. CH4 yields, volatile solids reduction, and energy recovery as CH4 from the sewage-grown water hyacinth were in the same range as those observed for other biomass substrates when digested under similar conditions.

  20. Methane production by anaerobic digestion of water hyacinth (Eichhornia crassipes)

    SciTech Connect

    Klass, D.L.; Ghosh, S.

    1980-01-01

    Water hyacinth under conventional high-rate digestion conditions exhibited higher methane yields and energy recovery efficiencies when grown in sewage-fed lagoons as compared to the corresponding values obtained with water hyacinth grown in a fresh-water pond. Mesophilic digestion provided the highest feed energy recovered in the product gas as methane while thermophilic digestion, when operated at sufficiently high loading rates and reduced detention times, gave the highest specific methane production rates. Methane yields, volatile solids reduction, and energy recovery as methane for the sewage-grown water hyacinth were in the same range as those observed for other biomass substrates when digested under similar conditions.

  1. Study on a fixed zeolite bioreactor for anaerobic digestion of ammonium-rich swine wastes.

    PubMed

    Wang, Qinghong; Yang, Yingnan; Yu, Cang; Huang, He; Kim, Mijung; Feng, Chuanping; Zhang, Zhenya

    2011-07-01

    In this study, a fixed zeolite bioreactor was developed for the anaerobic digestion of ammonium-rich swine wastes (NH(4)(+)-N=3770 mg/l). To investigate the performance of the reactor, a sunken zeolite bioreactor and a bioreactor without zeolite were used as controls. The new bioreactor exhibited good performance, with startup time on the 14th day and methane production of 178.5 ml/g-VS during all 32 days of the experiment at 35°C. This bioreactor significantly shortened startup time, enhanced methane gas yield more than twofold and made COD removal more efficient than under the other models. Furthermore, it reduced the inhibition of high ammonium concentration during the anaerobic digestion of ammonium-rich swine wastes via effective ammonium removal and the immobilisation of microorganisms. Because of its simple structure and good performance, the fixed zeolite bioreactor can be recommended for future use. PMID:21592787

  2. Growth and anaerobic digestion characteristics of microalgae cultivated using various types of sewage.

    PubMed

    Hidaka, Taira; Inoue, Kenichiro; Suzuki, Yutaka; Tsumori, Jun

    2014-10-01

    Microalgal cultivation combined with anaerobic digestion at wastewater treatment plants is promising to recover energy. This study investigated the growth and anaerobic digestion characteristics of microalgae cultivated using nutrients in sewage. Microalgae were cultivated using primary effluent, secondary effluent, and dewatering filtrate. Microscopic observation indicated that Chlorella was cultivated using dewatering filtrate of anaerobic digestion without controlling the type of species. Batch anaerobic digestion experiments with digested sludge showed that the methane conversion ratio of the cultivated mixture was approximately 40-65%. Different cultivation time did not affect the microalgal contents. Methane recovery mass was 0.13NL-methane/L-cultivation liquor. The C/N ratio of the cultivated mixture was approximately 3-5, but the apparent ammonia release ratio was smaller than that of sewage sludge during digestion. These results proved the applicability of methane recovery from microalgae cultivated using nutrients included in anaerobically digested sludge. PMID:25127007

  3. Using volatile fatty acid relationships to predict anaerobic digester failure

    SciTech Connect

    Hill, D.T.; Cobb, S.A.; Bolte, J.P.

    1987-01-01

    During recent years, a number of observations have been made in the literature regarding the level and ratio of certain organic acids and the correlation of these acid relationships with anaerobic digester performance, either complete failure or operation in a stressed state. It is an accepted fact that levels of organic acid are important in digestion for two reasons: (a) organic acids (particularly acetic) are the immediate precursors in the metabolic chain leading to methane formation and (b) if present in high concentration, acids are known to cause stress in the microbial population and can ultimately lead to complete process failure. The recent literature (approximately the last 7 years) was searched for digester performance data and organic acid levels. Seventy observations were used in arriving at a relationship between acetic acid level and propionic to acetic acid ratio and digester failure or success. Methane productivity (L CH4/g VS added) was used as the parameter determining digester performance. A definite trend was recognized that suggests acetic acid levels in excess of 800 mg/L or a propionic to acetic acid ratio greater than 1.4 indicate impending digester failure. A laboratory scale study was then conductd to verify this phenomenon. (Refs. 22).

  4. Tegoprens in anaerobic digestion of a mixture of cheese whey, poultry waste, and cattle dung for improved biomethanation

    SciTech Connect

    Patel, C.; Sastry, V.; Madamwar, D. [Sardar Patel Univ., Gujarat (India)

    1996-01-01

    To obtain enriched methane content and improve the anaerobic digestion of a mixture of cattle dung, poultry waste, and cheese whey, the effect of various doses of Tegoprens: T-3012, T-3099, T-5842, T-5843, T-5851, T-5852 has been studied, in bench-scale digesters. Among them, Tegoprens 3022 showed more than a 45% increase in gas production with higher methane content. 18 refs., 1 fig.

  5. Anaerobic digestion of solid fruit waste supplemented with poultry manure in a horizontal plug?flow reactor

    Microsoft Academic Search

    1984-01-01

    Anaerobic digestion of apple press cake in a horizontal plug?flow reactor (hydraulic residence time 40 d: 2.20 kg organic solids\\/m.d) resulted in 78.1% conversion of organic solids and a gas yield of 0.510 m\\/kg organic matter digested. Poultry manure fed weekly (4 kg total solids\\/m) as the sole source of supplementation maintained levels of 400 mg ammonia nitrogen\\/1 and 13

  6. Two-stage anaerobic co-digestion of waste activated sludge and fruit\\/vegetable waste using inclined tubular digesters

    Microsoft Academic Search

    R. M. Dinsdale; G. C. Premier; F. R. Hawkes; D. L. Hawkes

    2000-01-01

    The anaerobic co-digestion of a 10% total solids (7.4% VS) waste activated sludge\\/fruit and vegetable mixture with approximately 25% of the VS arising from the fruit and vegetable waste was studied in duplicate two-stage systems. Acidogenic CSTRs and methanogenic inclined tubular digesters operated at 30°C achieved stable anaerobic digestion at an overall system loading rate of 5.7 kg VS m?3

  7. Anaerobic digestion of solid waste: state-of-the-art.

    PubMed

    De Baere, L

    2000-01-01

    In order to make a correct assessment of the state-of-the-art of the technology, a study was made on the development of digestion capacity for solid waste in Europe. The study was limited to plants in operation or under construction that were treating at least 10% organic solid waste coming from market waste or municipal solid waste. A total treatment capacity for solid waste organics, excluding the tonnage used for sewage sludge and manures, evolved from 122,000 ton per year in 1990 to 1,037,000 ton available or under construction by the year 2000 in 53 plants across Europe, an increase by 750%. Both mesophilic and thermophilic technologies have been proven, with about 62% of capacity being operated at mesophilic temperatures. Wet and dry digestion are almost evenly split, while a clear choice was made for one-phase systems instead of two-phase systems, which represent only 10.6% of capacity. The capacity provided by co-digestion systems is limited, while there is a rising interest in digestion of mixed household waste. The reliable performance has been demonstrated for all types of anaerobic digestion systems. On the basis of the Dranco technology, a single-phase thermophilic dry digestion process, performances were reached similar to high-rate wastewater digestion. An annual average loading rate of 18.5 kg COD/m3.day, resulting in a biogas production of 9.2 m3/m3 reactor.day was obtained at a full-scale plant. The plant operated at a retention time of 15.3 days. Feedstocks range from clean organic wastes (31% dry matter) to heavily polluted grey waste organics (57% dry matter). Average dry matter concentrations of the digested residue of 41% were obtained. PMID:11382003

  8. Ultrasonic cell disruption of stabilised sludge with subsequent anaerobic digestion.

    PubMed

    Onyeche, T I; Schläfer, O; Bormann, H; Schröder, C; Sievers, M

    2002-05-01

    The world-wide increasing environmental awareness and its subsequent regulations have led to the application of improved technologies in wastewater purification plants. This has resulted in higher wastewater and sludge productions. Sludge is the by-product of such plants and it is not only rich in organic carbon and pathogens but also in heavy metals and other environmental pollutants. In Europe, agricultural application of dried sludge (bio-solids) is confronted with negative reactions from the citizens, governmental organisations, farmers and the food industry. Ultrasonic disruption of sludge is a popular mechanical disruption process in sludge treatment. During ultrasonic treatment, high frequency acoustic signals are used to initiate the cavitation process. The applied ultrasonic field leads to a breakdown of cohesive forces of the liquid molecules resulting in the generation of cavitation bubbles. A shock wave is released by the collapse of the cavitation bubbles and propagates in the surrounding medium forming jet streams that cause the disruption of cells in sludge. Disruption of sludge cells enables the release of light organic substances into the sludge water thereby exposing them for further anaerobic digestion. This paper presents results on the disruption of conventionally stabilised sludge through the application of the ultrasonic field. In order to reduce the specific energy input (i.e. ratio of the consumed energy during ultrasonic disruption to the input sludge mass) and improve biogas production, the total solids content of the stabilised sludge was increased before disruption. The anaerobic digestion of sludge samples was carried out in a set of specially constructed laboratory anaerobic digesters. Results showed that subsequent anaerobic digestion of the ultrasonically disrupted sludge could improve biogas production with reduced sludge quantity that is vital to the economic consideration of the wastewater treatment plants. This process encourages the exploitation of valuable materials and energy from stabilised sewage sludge just before its final disposal. The negative effects of mixing disrupted sludge with its separated sludge water are also shown in this paper. This expresses the microbiological instability of the anaerobic process caused by the mixing process. PMID:12159954

  9. Ultrasound pre-treatment for anaerobic digestion improvement.

    PubMed

    Pérez-Elvira, S; Fdz-Polanco, M; Plaza, F I; Garralón, G; Fdz-Polanco, F

    2009-01-01

    Prior research indicates that ultrasounds can be used in batch reactors as pre-treatment before anaerobic digestion, but the specific energy required at laboratory-scale is too high. This work evaluates both the continuous ultrasound device performance (efficiency and solubilisation) and the operation of anaerobic digesters continuously fed with sonicated sludge, and presents energy balance considerations. The results of sludge solubilisation after the sonication treatment indicate that, applying identical specific energy, it is better to increase the power than the residence time. Working with secondary sludge, batch biodegradability tests show that by applying 30 kWh/m3 of sludge, it is possible to increase biogas production by 42%. Data from continuous pilot-scale anaerobic reactors (V=100 L) indicate that operating with a conventional HRT=20 d, a reactor fed with pre-treated sludge increases the volatile solids removal and the biogas production by 25 and 37% respectively. Operating with HRT=15 d, the removal efficiency is similar to the obtained with a reactor fed with non-hydrolysed sludge at HTR=20 d, although the specific biogas productivity per volume of reactor is higher for the pretreated sludge. Regarding the energy balance, although for laboratory-scale devices it is negative, full-scale suppliers state a net generation of 3-10 kW per kW of energy used. PMID:19759455

  10. Microbial Ecology of Anaerobic Digesters: The Key Players of Anaerobiosis

    PubMed Central

    Ali Shah, Fayyaz; Mahmood, Qaisar; Maroof Shah, Mohammad; Pervez, Arshid; Ahmad Asad, Saeed

    2014-01-01

    Anaerobic digestion is the method of wastes treatment aimed at a reduction of their hazardous effects on the biosphere. The mutualistic behavior of various anaerobic microorganisms results in the decomposition of complex organic substances into simple, chemically stabilized compounds, mainly methane and CO2. The conversions of complex organic compounds to CH4 and CO2 are possible due to the cooperation of four different groups of microorganisms, that is, fermentative, syntrophic, acetogenic, and methanogenic bacteria. Microbes adopt various pathways to evade from the unfavorable conditions in the anaerobic digester like competition between sulfate reducing bacteria (SRB) and methane forming bacteria for the same substrate. Methanosarcina are able to use both acetoclastic and hydrogenotrophic pathways for methane production. This review highlights the cellulosic microorganisms, structure of cellulose, inoculum to substrate ratio, and source of inoculum and its effect on methanogenesis. The molecular techniques such as DGGE (denaturing gradient gel electrophoresis) utilized for dynamic changes in microbial communities and FISH (fluorescent in situ hybridization) that deal with taxonomy and interaction and distribution of tropic groups used are also discussed. PMID:24701142

  11. Multi-wavelength fluorometry for anaerobic digestion process monitoring.

    PubMed

    Morel, E; Santamaria, K; Perrier, M; Guiot, S R; Tartakovsky, B

    2005-01-01

    Applicability of multi-wavelength fluorometry for anaerobic digestion process monitoring was investigated in a 3.5 L upflow anaerobic sludge bed (UASB) lab-scale reactor. Both off-line and on-line monitoring of key process parameters was tested. Off-line emission spectra were measured at an angle of 90 degrees to the excitation beam using a cuvette. On-line measurements were carried out using a fiber optic probe in the external recirculation line of the digester. Fluorescence spectra were correlated to available analytical measurements to obtain partial least square regression models. An independent set of measurements was used to validate the regression models. Model estimations showed reasonable agreement with analytical measurements with multiple determination coefficients (R2) between 0.6 and 0.95. Results showed that offline fluorescence measurements can be used for fast estimation of anaerobic digestor effluent quality. At the same time, the on-line implementation of multi-wavelength fluorescence measurements can be used for realtime process monitoring and, potentially, for on-line process control. PMID:16180465

  12. Control strategy for maximum anaerobic co-digestion performance.

    PubMed

    García-Gen, Santiago; Rodríguez, Jorge; Lema, Juan M

    2015-09-01

    A control strategy for optimising the performance of anaerobic co-digestion in terms of methane productivity, digestate quality and process stability is presented. A linear programming approach is adopted to calculate the feeding of multiple substrates for maximum methane productivity, subjected to restrictions based on experimental and heuristic knowledge. Process stability is quantitatively assessed by an empirical diagnosis function comparing alkalinity ratio measurements against reference values (outputs between (-1,1]). A second empirical diagnosis function is defined to compare methane flow rate measurements against a reference value of maximum capacity (outputs between (0,1]). A variable-gain control function (outputs between (-1,1]), derived from the diagnosis functions, is defined to determine the quantitative change applied to the most active constraint of the substrate blend optimisation problem leading to a new set-point of feeding substrates blend. The control strategy works in a closed-loop architecture under which the process performance for each blend of substrates is continuously assessed. The system was successfully validated in a 1 m(3) hybrid Upflow Anaerobic Sludge Blanket - Anaerobic Filter (UASB-AF) reactor, treating blends of substrates (gelatine, glycerine and pig manure supernatant) at OLR values between 0.71 and 6.33 gCOD/L d over a period of 210 days at mesophilic conditions. PMID:26001824

  13. Optimization of solid state anaerobic digestion of the OFMSW by digestate recirculation: A new approach.

    PubMed

    Michele, Pognani; Giuliana, D'Imporzano; Carlo, Minetti; Sergio, Scotti; Fabrizio, Adani

    2015-01-01

    Dry anaerobic digestion (AD) of OFMSW was optimized in order to produce biogas avoiding the use of solid inoculum. Doing so the dry AD was performed irrigating the solid waste with liquid digestate (flow rate of 1:1.18-1:0.9 w/w waste/digestate; 21d of hydraulic retention time - HRT) in order to remove fermentation products inhibiting AD process. Results indicated that a high hydrolysis rate of organic matter (OM) and partial biogas production were obtained directly during the dry AD. Hydrolysate OM was removed from digester by the percolate flow and it was subsequently used to feed a liquid anaerobic digester. During dry AD a total loss of 36.9% of total solids was recorded. Methane balance indicated that 18.4% of potential methane can be produced during dry AD and 49.7% by the percolate. Nevertheless results obtained for liquid AD digestion indicated that only 20.4% and 25.7% of potential producible methane was generated by adopting 15 and 20 days of HRT, probably due to the AD inhibition due to high presence of toxic ammonia forms in the liquid medium. PMID:25305682

  14. Combining biocatalyzed electrolysis with anaerobic digestion

    Microsoft Academic Search

    P. Clauwaert; R. Tolêdo; D. van der Ha; R. Crab; W. Verstraete; H. Hu; K. M. Udert; K. Rabaey

    2008-01-01

    Biocatalyzed electrolysis is a microbial fuel cell based technology for the generation of hydrogen gas and other reduced products out of electron donors. Examples of electron donors are acetate and wastewater. An external power supply can support the process and therefore circumvent thermodynamical constraints that normally render the generation of compounds such as hydrogen unlikely. We have investigated the possibility

  15. Flow pattern visualization in a mimic anaerobic digester: experimental and computational studies.

    PubMed

    Vesvikar, M S; Varma, R; Karim, K; Al-Dahhan, M

    2005-01-01

    Advanced non-invasive experiments like computer automated radioactive particle tracking and computed tomography along with computational fluid dynamics (CFD) simulations were performed in mimic anaerobic digesters to visualize their flow pattern and obtain hydrodynamic parameters. The mixing in the digester was provided by sparging gas at three different flow rates. The simulation results in terms of overall flow pattern, location of circulation cells and stagnant regions, trends of liquid velocity profiles, and volume of dead zones agree reasonably well with the experimental data. CFD simulations were also performed on different digester configurations. The effects of changing draft tube size, clearance, and shape of the tank bottoms were calculated to evaluate the effect of digester design on its flow pattern. Changing the draft tube clearance and height had no influence on the flow pattern or dead regions volume. However increasing the draft tube diameter or incorporating a conical bottom design helped in reducing the volume of the dead zones as compared to a flat bottom digester. The simulations showed that the gas flow rate sparged by a single point (0.5 cm diameter) sparger does not have appreciable effect on the flow pattern of the digesters. PMID:16180475

  16. Anaerobic digestion of tannery waste: semi-continuous and anaerobic sequencing batch reactor processes.

    PubMed

    Zupancic, Gregor D; Jemec, A

    2010-01-01

    Disposal of the vast amounts of tannery waste that are currently generated is a significant problem. Anaerobic treatment of different types of tannery waste (fleshings, skin trimmings and wastewater sludge) was investigated. The biochemical methane potential is the same at 37 degrees C or 55 degrees C and an assay of this was shown to be an appropriate screening tool with which to estimate the susceptibility of a substrate to anaerobic digestion. The start-up procedure of a tannery waste thermophilic anaerobic digestion in 100 days using seed from mesophilic digester processing municipal sludge is presented. The specific methane production potential at 55 degrees C is estimated to be 0.617 m(3)kg(-1) of volatile suspended solids for tannery waste sludge, 0.377 m(3)kg(-1) for tannery waste trimmings and 0.649 m(3)kg(-1) for tannery waste fleshings. Additional concerns such as chromium content, salinity and temperature fluctuations were also addressed. Chromium content and salinity showed no adverse effects; however a reactor temperature reduction of 4.4 degrees C led to a drop in biogas production of 25%, indicating a requirement to keep the temperature constant at 55 degrees C. PMID:19699632

  17. Anaerobic digestion of secondary residuals from an anaerobic bioreactor at a brewery to enhance bioenergy generation.

    PubMed

    Bocher, Benjamin T; Agler, Matthew T; Garcia, Marcelo L; Beers, Allen R; Angenent, Largus T

    2008-05-01

    Many beer breweries use high-rate anaerobic digestion (AD) systems to treat their soluble high-strength wastewater. Biogas from these AD systems is used to offset nonrenewable energy utilization in the brewery. With increasing nonrenewable energy costs, interest has mounted to also digest secondary residuals from the high-rate digester effluent, which consists of yeast cells, bacteria, methanogens, and small (hemi)cellulosic particles. Mesophilic (37 degrees C) and thermophilic (55 degrees C) lab-scale, low-rate continuously-stirred anaerobic digestion (CSAD) bioreactors were operated for 258 days by feeding secondary residuals at a volatile solids (VS) concentration of approximately 40 g l(-1). At a hydraulic retention time (HRT) of 15 days and a VS loading rate of 2.7 g VS l(-1) day(-1), the mesophilic bioreactor showed an average specific volumetric biogas production rate of 0.88 l CH4 l(-1) day(-1) and an effluent VS concentration of 22.2 g VS l(-1) (43.0% VS removal efficiency) while the thermophilic bioreactor displayed similar performances. The overall methane yield for both systems was 0.21 l CH4 g(-1) VS fed and 0.47-0.48 l CH4 g(-1) VS removed. A primary limitation of thermophilic digestion of this protein-rich waste is the inhibition of methanogens due to higher nondissociated (free) ammonia (NH3) concentrations under similar total ammonium (NH4+) concentrations at equilibrium. Since thermophilic AD did not result in advantageous methane production rates or yields, mesophilic AD was, therefore, superior in treating secondary residuals from high-rate AD effluent. An additional digester to convert secondary residuals to methane may increase the total biogas generation at the brewery by 8% compared to just conventional high-rate digestion of brewery wastewater alone. PMID:18188623

  18. DIGESTER GAS - FUEL CELL - PROJECT

    SciTech Connect

    Dr.-Eng. Dirk Adolph; Dipl.-Eng. Thomas Saure

    2002-03-01

    GEW has been operating the first fuel cell in Europe producing heat and electricity from digester gas in an environmentally friendly way. The first 9,000 hours in operation were successfully concluded in August 2001. The fuel cell powered by digester gas was one of the 25 registered ''Worldwide projects'' which NRW presented at the EXPO 2000. In addition to this, it is a key project of the NRW State Initiative on Future Energies. All of the activities planned for the first year of operation were successfully completed: installing and putting the plant into operation, the transition to permanent operation as well as extended monitoring till May 2001.

  19. Combustion of anaerobically digested humus as a fuel

    SciTech Connect

    Kayhanian, M.; Jenkins, B.M. [Univ. of California, Davis, CA (United States); Baxter, L.L. [Sandia National Labs., Livermore, CA (United States)] [and others

    1994-12-31

    Two pilot scale combustion experiments were conducted to explore the application of an anaerobically digested humus as fuel for commercial boilers. The experiments were performed in a fluidized bed combustor (FBC) and a multifuel suspension combustor (MFC). The results obtained indicate that the humus, blended with another conventional fuel (e.g., wood), can be used as a fuel in commercial boilers. Preliminary results of ash deposit analyses from the MFC indicate that the rate of deposition was low compared to high fouling biomass fuels such as straws, and similar to deposits obtained from wood.

  20. Anaerobic digestion of food waste using yeast.

    PubMed

    Suwannarat, Jutarat; Ritchie, Raymond J

    2015-08-01

    Fermentative breakdown of food waste seems a plausible alternative to feeding food waste to pigs, incineration or garbage disposal in tourist areas. We determined the optimal conditions for the fermentative breakdown of food waste using yeast (Saccharomyces cerevisiae) in incubations up to 30days. Yeast efficiently broke down food waste with food waste loadings as high as 700g FW/l. The optimum inoculation was ?46×10(6)cells/l of culture with a 40°C optimum (25-40°C). COD and BOD were reduced by ?30-50%. Yeast used practically all the available sugars and reduced proteins and lipids by ?50%. Yeast was able to metabolize lipids much better than expected. Starch was mobilized after very long term incubations (>20days). Yeast was effective in breaking down the organic components of food waste but CO2 gas and ethanol production (?1.5%) were only significant during the first 7days of incubations. PMID:25987287

  1. Terminal reactions in the anaerobic digestion of animal waste

    Microsoft Academic Search

    1982-01-01

    An anaerobic mesophilic digestor was operated using beef cattle waste (diluted to 5.75% volatile solids) as substrate; retention time was 10 days with daily batch feed. Volatile solids destruction was 36%. Daily gas production rate was 1.8 liters of gas (standard temperature and pressure) per liter of digestor contents (0.99 liters of CHâ per liter of digestor contents). Acetate turnover

  2. Investigation of Poultry Waste for Anaerobic Digestion: A Case Study

    NASA Astrophysics Data System (ADS)

    Salam, Christopher R.

    Anaerobic Digestion (AD) is a biological conversion technology which is being used to produce bioenergy all over the world. This energy is created from biological feedstocks, and can often use waste products from various food and agricultural processors. Biogas from AD can be used as a fuel for heating or for co-generation of electricity and heat and is a renewable substitute to using fossil fuels. Nutrient recycling and waste reduction are additional benefits, creating a final product that can be used as a fertilizer in addition to energy benefits. This project was conducted to investigate the viability of three turkey production wastes as AD feedstock: two turkey litters and a material separated from the turkey processing wastewater using dissolved air flotation (DAF) process. The DAF waste contained greases, oils and other non-commodity portions of the turkey. Using a variety of different process methods, types of bacteria, loading rates and food-to-microorganism ratios, optimal loading rates for the digestion of these three materials were obtained. In addition, the co-digestion of these materials revealed additional energy benefits. In this study, batch digestion tests were carried out to treat these three feedstocks, using mesophilic and thermophilic bacteria, using loading rates of 3 and 6 gVS/L They were tested separately and also as a mixture for co-digestion. The batch reactor used in this study had total and working volumes of 1130 mL and 500 mL, respectively. The initial organic loading was set to be 3 gVS/L, and the food to microorganism ratio was either 0.6 or 1.0 for different treatments based on the characteristics of each material. Only thermophilic (50 +/- 2ºC) temperatures were tested for the litter and DAF wastes in continuous digestion, but mesophilic and thermophilic batch digestion experiments were conducted. The optimum digestion time for all experiments was 14 days. The biogas yields of top litter, mixed litter, and DAF waste under mesophilic batch conditions all at 3 gVS/L loading were determined to be 148.6 +/- 7.82, 176.5 +/- 11.1 and 542.0 +/- 37.9 mL/ gVS, respectively and were 201.9 +/- 10.0, 210.4 +/- 29.3, and 419.3 +/- 12.1 mL/gVS, respectively, for initial loading of 6 gVS/L. Under thermophilic batch conditions, the top litter, mixed litter, and DAF waste had the biogas yields of 255.3 +/- 7.9, 313.4 +/- 30.1and 297.4 +/- 33.8 mL/gVS for loading rate of 3 gVS/L and 233.8 +/- 45.3, 306.5 +/- 11.8 and 185.1 +/- 0.85 mL/gVS for loading rate of 6 gVS/L. The biogas yields from co-digestion of the mixed litter and DAF waste at 3 gVS/L were 461.8 +/- 41.3 mL/gVS under thermophilic conditions. The results from batch anaerobic digestion tests were then used for designing continuous digestion experiments. All the continuous digestion experiments were conducted by using an Anaerobic Phase Solids (APS) digester system operated at a thermophilic temperature. The total volume of the continuous digester system was 4.8 L and the working volume was around 4.4 L. The APS digester system had two hydrolysis reactors and one biogasification reactor. Feedstock was loaded into the hydrolysis reactors in batches. The feedstock digestion time was 14 days and the average organic loading rate (OLR) of the system was 3 gVS/L/day. The experiment has three distinct feedstock stages, first with turkey litter waste, a co-digestion of DAF and turkey litter waste, followed by DAF waste. The biogas yields were determined to be 305.2 +/- 70.6 mL/gVS/d for turkey mixed litter, 455.8 +/- 77.2 mL/gVS/d during the mixture of mixed litter and DAF waste, and 382.0 +/- 39.6 mL/gVS for DAF waste. The biogas yields from the thermophilic batch test yields compare with that of the continuous digester yields. For experiments utilizing turkey litter, batch tests yielded 313.4 +/- 30.1mL/gVS biogas and 305.2 +/- 70.6 mL/gVS/d for continuous experiments. For experiments using codigestion of turkey litter and DAF waste, batches yielded 461.8 +/- 41.3 mL/gVS biogas comparing well to continuous digester operation that yielded 455.8 +/- 77.

  3. Simulation of low temperature anaerobic digestion of dairy and swine manure q

    E-print Network

    Simulation of low temperature anaerobic digestion of dairy and swine manure q D.T. Hill *, S di- gestion of dairy and swine manure at psychrophilic temperatures (i.e., 10±23°C) have been used Elsevier Science Ltd. All rights reserved. Keywords: Animal-waste; Simulation; Anaerobic-digestion; Swine

  4. Aeration of anaerobically digested sewage sludge for COD and nitrogen removal: optimization at large-scale

    Microsoft Academic Search

    V. Parravicini; K. Svardal; R. Hornek; H. Kroiss

    2008-01-01

    The paper will report about the experiences matured at an Austrian large wastewater treatment plant of 720.000 population equivalents, where anaerobically digested sewage sludge is further stabilised under aerobic conditions. Enhanced stabilisation of the anaerobically digested sludge was required at the plant in order to get a permit for landfill disposal of the dewatered stabilized sludge. By implementing a post-aeration

  5. Speciation modeling of ammonia and other major solutes in anaerobic digesters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic digestion of high-nitrogen wastes can be inhibited by high concentrations of un-ionized ammonia, NH**3 (aq). Understanding the toxicity of NH**3 (aq) to anaerobic digestion requires an understanding of the mechanisms controlling its concentration. Previous work on ammonia toxicity in an...

  6. PRODUCTION OF VOLATILE FATTY ACIDS BY STRICTLY ANAEROBIC BACTERIA IN THE DIGESTIVE TRACT OF GNOTOXENIC MICE.

    E-print Network

    Paris-Sud XI, Université de

    SUMMARY PRODUCTION OF VOLATILE FATTY ACIDS BY STRICTLY ANAEROBIC BACTERIA IN THE DIGESTIVE TRACT OF « GNOTOXENIC » MICE. INHIBITORY EFFECT ON SHIGELLA FLEXNERI Various strains of strictly anaerobic bacteria of holoxenic animals, were implanted in the digestive tract of axenic mice. The in vivo production of VFA

  7. Denitrification in anaerobic digesters: Possibilities and influence of wastewater COD\\/N?NOX ratio

    Microsoft Academic Search

    J. C. Akunna; C. Bizeau; R. Moletta

    1992-01-01

    Laboratory?scale completely?stirred anaerobic digesters were fed with synthetic wastewaters containing nitrate and nitrite and with glucose as the only source of organic carbon in order to investigate and compare the denitrification potentials of anaerobic digesters in the presence of nitrate and nitrite. Varying the input nitrate and nitrite concentration at fixed COD and HRT, methane production without denitrification occurred at

  8. Characterization and environmental studies of Pompano Beach anaerobic digestion facility. Semi-annual report

    SciTech Connect

    Sengupta, S; Farooq, S; Gerrish, H P; Wong, K F; Daly, Jr, E L; Chriswell, C

    1980-02-01

    Anaerobic digestion of municipal waste has been demonstrated to be feasible in bench scale experiments by Pfeffer (1974). Approximately, 50% reduction in mass and production of 6000 ft/sup 3/ of gas/ton have been estimated. The gas composition is estimated to be 50% methane and 50% carbon monoxide. The technical and economic feasibility of anaerobic digestion with an ultimate objective of commercialization are discussed. A plant has been built at Pompano Beach, Florida on an existing shredding and landfill operation site. The plant design capacity is 100 tons/day. Two digesters have been constructed to be used in parallel. The process consists of primary shredding, metal separation, secondary shredding, air classification and digestion of light fraction. Sewage sludge was used to seed the initial mixture in the digester. The output slurry is vacuum filtered and the filter cake disposed on an existing landfill. The filtrate is recycled. Excess filtrate is sprayed on the landfill. At present the output gas is being flared. A flow chart for the plant is presented. It is imperative that environmental investigations be conducted on new energy technology prior to commercialization. A project was initiated to characterize all input and output streams and to assess the potential for ground water contamination by landfill disposal of effluents. Detailed chemical, biological and physical characterization efforts supported by leaching and modelling studies are being conducted to achieve the stated objectives. Some mutagenic studies were also conducted. The environmental investigations were started in August 1978. Sengupta et al (1979a) reported the first year's efforts.

  9. Development of an advanced anaerobic digester design and a kinetic model for biogasification of water hyacinth/sludge blends

    SciTech Connect

    Srivastava, V.; Fannin, K.F.; Biljetina, R.; Chynoweth, D.P.; Hayes, T.D.

    1986-07-01

    The Institute of Gas Technology (IGT) conducted a comprehensive laboratory-scale research program to develop and optimize the anaerobic digestion process for producing methane from water hyacinth and sludge blends. This study focused on digester design and operating techniques, which gave improved methane yields and production rates over those observed using conventional digesters. The final digester concept and the operating experience was utilized to design and operate a large-scale experimentla test unit (ETU) at Walt Disney World, Florida. This paper describes the novel digester design, operating techniques, and the results obtained in the laboratory. The paper also discusses a kinetic model which predicts methane yield, methane production rate, and digester effluent solids as a function of retention time. This model was successfully utilized to predict the performance of the ETU. 15 refs., 6 figs., 6 tabs.

  10. Horsepower requirements for high-solids anaerobic digestion

    SciTech Connect

    Rivard, C.J.; Kay, B.D.; Kerbaugh, D.H. [National Renewable Energy Lab., Golden, CO (United States)

    1995-12-31

    Improved organic loading rates for anaerobic bioconversion of cellulosic feedstocks are possible through high-solids processing. Additionally, the reduction in process water for such a system further improves the economics by reducing the overall size of the digestion system. However, mixing of high-solids materials is often viewed as an energy-intensive part of the process. Although the energy demand for high-solids mixing may be minimized by improving the agitator configuration and reducing the mixing speed, relatively little information is available for the actual horsepower requirements of a mechanically mixed high-solids digester system. The effect of sludge total solids content and digester fill level on mixing power requirements was evaluated using a novel NREL laboratory-scale high-solids digester. Trends in horsepower requirements are shown that establish the optimum parameters for minimizing mixing energy requirements, while maintaining adequate solids blending for biological activity. The comparative relationship between laboratory-scale mixing energy estimates and those required for scale-up systems is also established.

  11. Anaerobic digestion of the organic fraction of municipal solid waste: Influence of co-digestion with manure

    Microsoft Academic Search

    Hinrich Hartmann; Birgitte K. Ahring

    2005-01-01

    Anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was investigated in two thermophilic (55°C) wet digestion treatment systems R1 and R2. Initially OFMSW was co-digested with manure with a successively higher concentration of OFMSW, at a hydraulic retention time (HRT) of 14–18d and an organic loading rate (OLR) of 3.3–4.0g-VS\\/l\\/d. Adaptation of the co-digestion process to a

  12. 5-Cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction in a mesophilic anaerobic digester: Measuring redox behavior,

    E-print Network

    Pace, Norman

    5-Cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction in a mesophilic anaerobic digester in microcosms containing active anaerobic digester biomass, propylene glycol, and settled sewage centrate. In addition, activity assessment in anaerobic digesters using FISH and CTC reduction assays may be comparable

  13. Can we assess the model complexity for a bioprocess ? Theory and example of the anaerobic digestion process

    E-print Network

    Boyer, Edmond

    Can we assess the model complexity for a bioprocess ? Theory and example of the anaerobic digestion the bioreactor. This provides the dimension of K. The method is applied to data from an anaerobic digestion can be obtained with 2 biomasses. Keywords Anaerobic digestion; Bioreactors; Modelling; Nonlinear

  14. Repeated pulse feeding induces functional stability in anaerobic digestion

    PubMed Central

    De Vrieze, Jo; Verstraete, Willy; Boon, Nico

    2013-01-01

    Summary Anaerobic digestion is an environmental key technology in the future bio-based economy. To achieve functional stability, a minimal microbial community diversity is required. This microbial community should also have a certain ‘elasticity’, i.e. the ability to rapidly adapt to suboptimal conditions or stress. In this study it was evaluated whether a higher degree of functional stability could be achieved by changing the feeding pattern, which can change the evenness, dynamics and richness of the bacterial community. The first reactor (CSTRstable) was fed on daily basis, whereas the second reactor (CSTRdynamic) was fed every 2 days. Average biogas production was 0.30?l CH4 l?1 day?1 in both reactors, although daily variation was up to four times higher in the CSTRdynamic compared with the CSTRstable during the first 50 days. Bacterial analysis revealed that this CSTRdynamic had a two times higher degree of bacterial community dynamics. The CSTRdynamic also appeared to be more tolerant to an organic shock load of 8?g COD l?1 and ammonium levels up to 8000?mg TAN l?1. These results suggest that the regular application of a limited pulse of organic material and/or a variation in the substrate composition might promote higher functional stability in anaerobic digestion. PMID:23302421

  15. Degradation properties of protein and carbohydrate during sludge anaerobic digestion.

    PubMed

    Yang, Guang; Zhang, Panyue; Zhang, Guangming; Wang, Yuanyuan; Yang, Anqi

    2015-09-01

    Degradation of protein and carbohydrate is vital for sludge anaerobic digestion performance. However, few studies focused on degradation properties of protein and carbohydrate. This study investigated detailed degradation properties of sludge protein and carbohydrate in order to gain insight into organics removal during anaerobic digestion. Results showed that carbohydrate was more efficiently degraded than protein and was degraded prior to protein. The final removal efficiencies of carbohydrate and protein were 49.7% and 32.2%, respectively. The first 3days were a lag phase for protein degradation since rapid carbohydrate degradation in this phase led to repression of protease formation. Kinetics results showed that, after initial lag phase, protein degradation followed the first-order kinetic with rate constants of 0.0197 and 0.0018d(-1) during later rapid degradation phase and slow degradation phase, respectively. Carbohydrate degradation also followed the first-order kinetics with a rate constant of 0.007d(-1) after initial quick degradation phase. PMID:26025350

  16. Toxicity and biodegradability of olive mill wastewaters in batch anaerobic digestion

    Microsoft Academic Search

    Moktar Hamdi

    1992-01-01

    The anaerobic biodegradability and toxicity of olive mill waste-waters (OMW) were studied in batch anaerobic digestion experiments.\\u000a Anaerobic digestion of OMW or the supernatant of its centrifugation, the methane production was achieved at up to 5–15% (V\\/V)\\u000a dilution corresponding to only 5–20 g\\/L COD. The washed suspended solids of OMW were toxic at up to 80 g\\/L COD; however, the

  17. [Municipal biowaste thermal-hydrolysis and ASBR anaerobic digestion].

    PubMed

    Hou, Hua-hua; Wang, Wei; Hu, Song; Xu, Yi-xian

    2010-02-01

    Thermal-hydrolysis can remarkably improve the solid organics dissolving efficiency of urban biomass waste, and anaerobic sequencing batch reactor (ASBR) was used to improve the efficiency of urban biomass waste anaerobic digestion. The optimum thermal-hydrolysis temperature and holding time was 175 degrees C and 60 min, the volatile suspended solid (VSS) dissolving ratio of kitchen waste, fruit-and-vegetable waste and sludge were 31.3%, 31.9% and 49.7%, respectively. Two ASBR and one continuous-flow stirred tank reactor (CSTR) were started at hydraulic retention time (HRT) = 20 d, COD organic loading rate (OLR) = 3.2-3.6 kg/(m3 x d). The biogas production volumes were 5656 mL/d(A1), 6335 mL/d(A2) and 3 103 mL/d(CSTR), respectively; VSS degradation ratios were 45.3% (A1), 50.87% (A2), 20.81% (CSTR), and the total COD (TCOD) removal rates were 88.1% (A1), 90% (A2), 72.6% (CSTR). In ASBR, organic solid and anaerobic microorganism were remained in the reactor during settling period. When HRT was 20 d, the solid retention time (SRT) was over 130 d, which made ASBR higher efficiency than CSTR. PMID:20391728

  18. Impact of food industrial waste on anaerobic co-digestion of sewage sludge and pig manure

    Microsoft Academic Search

    M Murto; L Björnsson; B Mattiasson

    2004-01-01

    The performance of an anaerobic digestion process is much dependent on the type and the composition of the material to be digested. The effects on the degradation process of co-digesting different types of waste were examined in two laboratory-scale studies. In the first investigation, sewage sludge was co-digested with industrial waste from potato processing. The co-digestion resulted in a low

  19. Anaerobic digestion of organic solid wastes. An overview of research achievements and perspectives

    Microsoft Academic Search

    J Mata-Alvarez; S Macé; P Llabrés

    2000-01-01

    The technology of anaerobic digestion of organic solid wastes is, in many aspects, mature. Topics such as fundamentals (kinetics, modelling, etc.), process aspects (performance, two- and single-phase systems, wet and dry technologies), digestion enhancement (several pre-treatments), co-digestion with other substrates and its relation to composting technology are examined in this review. Special attention is paid to the advantages of anaerobic

  20. Biogas energy production from tropical biomass wastes by anaerobic digestion.

    PubMed

    Ge, Xumeng; Matsumoto, Tracie; Keith, Lisa; Li, Yebo

    2014-10-01

    Anaerobic digestion (AD) is an attractive technology in tropical regions for converting locally abundant biomass wastes into biogas which can be used to produce heat, electricity, and transportation fuels. However, investigations on AD of tropical forestry wastes, such as albizia biomass and food wastes, such as taro, papaya, and sweet potato, are limited. In this study, these tropical biomass wastes were evaluated for biogas production by liquid AD (L-AD) and/or solid-state AD (SS-AD), depending on feedstock characteristics. When albizia leaves and chips were used as feedstocks, L-AD had greater methane yields (161 and 113 L kg(-1)VS, respectively) than SS-AD (156.8 and 59.6 L kg(-1)VS, respectively), while SS-AD achieved 5-fold higher volumetric methane productivity than L-AD. Mono-digestion and co-digestion of taro skin, taro flesh, papaya, and sweet potato achieved methane yields from 345 to 411 L kg(-1)VS, indicating the robustness of AD technology. PMID:25022835

  1. Microalgae to biofuels: life cycle impacts of methane production of anaerobically digested lipid extracted algae.

    PubMed

    Quinn, Jason C; Hanif, Asma; Sharvelle, Sybil; Bradley, Thomas H

    2014-11-01

    This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina. Results show whole microalgae produced 430 cm(3)-CH4 g-volatile solids(-1) (g-VS) (?=60), 3 times more methane than was produced by the LEA, 140 cm(3)-CH4 g-VS(-1) (?=30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. PMID:25181698

  2. Anaerobic co-digestion of kitchen waste and pig manure with different mixing ratios.

    PubMed

    Tian, Hailin; Duan, Na; Lin, Cong; Li, Xue; Zhong, Mingzhu

    2015-07-01

    Anaerobic co-digestion of kitchen waste (KW) and pig manure (PM) with seven different PM to KW total solids (TS) ratios of 1:0, 5:1, 3:1, 1:1, 1:3, 1:5 and 0:1 was conducted at mesophilic temperature (35 ± 1°C) to investigate the feasibility and process performance. The co-digestion of PM and KW was found to be an available way to enhance methane production compared with solo-digestion of PM or KW. The ratio of PM to KW of 1:1 got the highest biodegradability (BDA) of 85.03% and a methane yield of 409.5 mL/gVS. For the co-digestion of KW and PM, there was no obvious inhibition of ammonia nitrogen because it was in an acceptable range from 1380 mg/L to 2020 mg/L in the whole process. However, severe methane inhibition and long lag phase due to the accumulation of volatile fatty acids (VFAs) was observed while the KW content was over 50%, and in the lag phase, propionic acid and butyric acid made up the major constituents of the total VFAs. The technical digestion time (T80: the time it takes to produce 80% of the digester's maximum gas production) of the above 7 ratios was 15, 21, 22, 27, 49, 62 and 61 days, respectively. In this study, a mixing ratio of 1:1 for PM and KW was found to maximize BDA and methane yield, provided a short digestion time and stable digestion performance and was therefore recommended for further study and engineering application. PMID:25617184

  3. Do two-phase biogas plants separate anaerobic digestion phases? - a mathematical model for the distribution of anaerobic digestion phases among reactor stages.

    PubMed

    Muha, Ivo; Zielonka, Simon; Lemmer, Andreas; Schönberg, Mandy; Linke, Bernd; Grillo, Alfio; Wittum, Gabriel

    2013-03-01

    In this article a mathematical model is introduced, which estimates the distribution of the four anaerobic digestion phases (hydrolysis, acidogenesis, acetogenesis and methanogenesis) that occur among the leach bed reactor and the anaerobic filter of a biogas plant. It is shown that only the hydrolysis takes place in the first stage (leach bed reactor), while all other anaerobic digestion phases take place in both reactor stages. It turns out that, besides the usually measured raw materials of the acetogenesis and the methanogenesis phases (organic acids), it is also necessary to analyze the process liquid for raw materials of the acidogenesis phase, i.e., sugars, fatty acids, amino acids, etc. The introduced model can be used to monitor the inhibition of the anaerobic digestion phases in reactor stages and can, thus, help to improve the control system of biogas plants. PMID:23290872

  4. Data summary of municipal solid waste management alternatives. Volume 10, Appendix H: Anaerobic digestion of MSW

    SciTech Connect

    none,

    1992-10-01

    While municipal solid waste (MSW) thermoconversion and recycling technologies have been described in Appendices A through E, this appendix addresses the role of bioconversion technologies in handling the organic fraction in MSW and sewage sludge. Much of the organic matter in MSW, consisting mainly of paper, food waste, and yard waste, has potential for conversion, along with sewage sludge, through biochemical processes to methane and carbon dioxide providing a measurable, renewable energy resource potential. The gas produced may be treated for removal of carbon dioxide and water, leaving pipeline quality gas. The process also has the potential for producing a stabilized solid product that may be suitable as a fuel for combustion or used as a compost fertilizer. Anaerobic digestion can occur naturally in an uncontrolled environment such as a landfill, or it can occur in a controlled environment such as a confined vessel. Landfill gas production is discussed in Appendix F. This appendix provides information on the anaerobic digestion process as it has been applied to produce methane from the organic fraction of MSW in enclosed, controlled reactors.

  5. Mixed culture model of anaerobic digestion: application to the evaluation of startup procedures

    Microsoft Academic Search

    Alberto Dalla Torre; G. Stephanopoulos

    1986-01-01

    The successful operation of anaerobic digestion depends on the balanced growth of many bacterial species. The functions of the main groups of microorganisms present in a digester have been analyzed and a mathematical model constructed that describes the interactions among the microbial populations and their effect on the digester performance. The model was validated by comparing its predictions with actual

  6. Solubilization of particulate organic carbon during the acid phase of anaerobic digestion

    Microsoft Academic Search

    J. A. Eastman; J. F. Ferguson

    1981-01-01

    Hydrolysis of particulates to soluble substrates rather than bacterial growth was the rate-limiting step during the acid phase of anaerobic digestion of sewage sludge, and pH had a greater effect on the process than did influent solids concentrations, suggesting that digestability can be improved for highly variable feed sludges by separate phase digestion for acid production and CHâ production. Carbohydrates

  7. Survey of the Anaerobic Biodegradation Potential of Organic Chemicals in Digesting Sludge

    PubMed Central

    Battersby, Nigel S.; Wilson, Valerie

    1989-01-01

    The degradation potential of 77 organic chemicals under methanogenic conditions was examined with an anaerobic digesting sludge from the United Kingdom. Degradation was assessed in terms of net total gas (CH4 plus CO2) produced, expressed as a percentage of the theoretical production (ThGP). The compounds tested were selected from various chemical groups and included substituted phenols and benzoates, pesticides, phthalic acid esters, homocyclic and heterocyclic ring compounds, glycols, and monosubstituted benzenes. The results obtained were in good agreement with published surveys of biodegradability in U.S. digesting sludges and other methanogenic environments. In general, the presence of chloro or nitro groups inhibited anaerobic gas production, while carboxyl and hydroxyl groups facilitated biodegradation. The relationship between substituent position and susceptibility to methanogenic degradation was compound dependent. The following chemicals were completely degraded (?80% ThGP) at a concentration of 50 mg of carbon per liter: phenol, 2-aminophenol, 4-cresol, catechol, sodium benzoate, 4-aminobenzoic acid, 3-chlorobenzoic acid, phthalic acid, ethylene glycol, diethylene glycol, triethylene glycol, sodium stearate, and quinoline. 3-Cresol, 4-chlorobenzoic acid, dimethyl phthalate, and pyridine were partially degraded. Although the remaining chemicals tested were either persistent or toxic, their behavior may differ at more environmentally realistic chemical-to-biomass ratios. Our findings suggest that biodegradability assessments made with sludge from one source can be extrapolated to sludge from another source with a reasonable degree of confidence and should help in predicting the fate of an organic chemical during the anaerobic digestion of sewage sludge. PMID:16347851

  8. Phycoremediation coupled production of algal biomass, harvesting and anaerobic digestion: possibilities and challenges.

    PubMed

    Prajapati, Sanjeev Kumar; Kaushik, Prachi; Malik, Anushree; Vijay, Virendra Kumar

    2013-12-01

    Biogas produced from anaerobic digestion is a versatile and environment friendly fuel which traditionally utilizes cattle dung as the substrate. In the recent years, owing to its high content of biodegradable compounds, algal biomass has emerged as a potential feedstock for biogas production. Moreover, the ability of algae to treat wastewater and fix CO2 from waste gas streams makes it an environmental friendly and economically feasible feedstock. The present review focuses on the possibility of utilizing wastewater as the nutrient and waste gases as the CO2 source for algal biomass production and subsequent biogas generation. Studies describing the various harvesting methods of algal biomass as well as its anaerobic digestion have been compiled and discussed. Studies targeting the most recent advancements on biogas enrichment by algae have been discussed. Apart from highlighting the various advantages of utilizing algal biomass for biogas production, limitations of the process such as cell wall resistivity towards digestion and inhibitions caused due to ammonia toxicity and the possible strategies for overcoming the same have been reviewed. The studies compiled in the present review indicate that if the challenges posed in translating the lab scale studies on phycoremediation and biogas production to pilot scale are overcome, algal biogas could become the sustainable and economically feasible source of renewable energy. PMID:23827782

  9. Anaerobic digestion of autoclaved and untreated food waste

    SciTech Connect

    Tampio, Elina, E-mail: elina.tampio@mtt.fi [Bioenergy and Environment, MTT Agrifood Research Finland, FI-31600 Jokioinen (Finland); Ervasti, Satu; Paavola, Teija [Bioenergy and Environment, MTT Agrifood Research Finland, FI-31600 Jokioinen (Finland); Heaven, Sonia; Banks, Charles [University of Southampton, Faculty of Engineering and the Environment, Southampton SO17 1BJ (United Kingdom); Rintala, Jukka [Bioenergy and Environment, MTT Agrifood Research Finland, FI-31600 Jokioinen (Finland)

    2014-02-15

    Highlights: • Autoclaving decreased the formation of NH4-N and H{sub 2}S during food waste digestion. • Stable digestion was achieved with untreated and autoclaved FW at OLR 6 kg VS/m{sup 3}day. • Use of acclimated inoculum allowed very rapid increases in OLR. • Highest CH{sub 4} yields were observed at OLR 3 kg VS/m{sup 3}day with untreated FW. • Autoclaved FW produced highest CH{sub 4} yields during OLR 4 kgVS/m{sup 3}day. - Abstract: Anaerobic digestion of autoclaved (160 °C, 6.2 bar) and untreated source segregated food waste (FW) was compared over 473 days in semi-continuously fed mesophilic reactors with trace elements supplementation, at organic loading rates (OLRs) of 2, 3, 4 and 6 kg volatile solids (VS)/m{sup 3} d. Methane yields at all OLR were 5–10% higher for untreated FW (maximum 0.483 ± 0.013 m{sup 3} CH{sub 4}/kg VS at 3 kg VS/m{sup 3} d) than autoclaved FW (maximum 0.439 ± 0.020 m{sup 3} CH{sub 4}/kg VS at 4 kg VS/m{sup 3} d). The residual methane potential of both digestates at all OLRs was less than 0.110 m{sup 3} CH{sub 4}/kg VS, indicating efficient methanation in all cases. Use of acclimated inoculum allowed very rapid increases in OLR. Reactors fed on autoclaved FW showed lower ammonium and hydrogen sulphide concentrations, probably due to reduced protein hydrolysis as a result of formation of Maillard compounds. In the current study this reduced biodegradability appears to outweigh any benefit due to thermal hydrolysis of ligno-cellulosic components.

  10. Pretreatment technologies for advancing anaerobic digestion of pulp and paper biotreatment residues.

    PubMed

    Elliott, Allan; Mahmood, Talat

    2007-11-01

    While anaerobic digestion is commonly practiced in the municipal sector, it has not gained popularity in the pulp and paper industry mainly because of its long sludge residence time requirement of 20-30 days. The construction of large digesters to provide such extended residence times is capital-intensive and thus the implementation of anaerobic digestion has remained economically prohibitive. A review of the literature suggests that recent developments in sludge preconditioning technologies have substantially reduced the sludge residence time requirement to the order of 7 days. Also, the preconditioned sludges have been reported to hold potential for higher methane recovery with reduced excess sludge production requiring disposal. Such advantages, coupled with escalating fuel prices and the introduction of carbon credits under the Kyoto Accord, have significantly improved the economics of anaerobic digestion. As the cost of sludge management varies from one mill to another, mill-specific economic assessment of anaerobic digestion could identify cost-saving opportunities. PMID:17628630

  11. Enhancing the quality of bio-oil and selectivity of phenols compounds from pyrolysis of anaerobic digested rice straw.

    PubMed

    Liang, Jiajin; Lin, Yunqin; Wu, Shubin; Liu, Chao; Lei, Ming; Zeng, Chao

    2015-04-01

    This study investigated the thermal decomposition characteristics and pyrolytic products of anaerobic digested rice straw (ADRS) by thermogravimetric (TG) and pyrolysis-gas chromatograph/mass spectrometry (Py-GC/MS) analysis. Compared with the raw rice straw (RS), the thermal decomposition temperature of ADRS was shifted to higher temperature zone and the second decomposition zone of cellulose (Toffset(c)-Tpeak) became narrower (14 °C less), which indicated that the composition of rice straw were changed significantly by the anaerobic digestion pretreatment. Py-GC/MS analysis showed that the quality of the bio-oil and the selectivity of pyrolytic products could be obviously improved by anaerobic digestion. The total yields of alcohols, acids, aldehydes, furans, anhydrosugars, and ketones pyrolysis substances decreased, while the yield of phenols increased. The yield of 4-Vinylphenol (4-VP) increased from 29.33%, 8.21% and 5.76% to 34.93%, 12.46% and 7.68% at 330, 450 and 650 °C, respectively, after anaerobic digestion. PMID:25647031

  12. Application of low-strength ultrasonication to the continuous anaerobic digestion processes: UASBr and dry digester.

    PubMed

    Cho, Si-Kyung; Kim, Dong-Hoon; Jeong, In-Seok; Shin, Hang-Sik; Oh, Sae-Eun

    2013-08-01

    In this study, the positive effects of low-strength ultrasonication (LS-ultrasonication) on the anaerobic digestion (AD) performance were investigated by continuously operating an upflow anaerobic sludge blanket reactor (UASBr) and a dry digester. In the ultrasonicated UASBr system (1 s per min, 0.05 W/mL), ultrasonication enhanced the CH? production by 38% and 19% in an ambient and a mesophilic condition, respectively. In addition, a different sludge yield and a changed electron flow were observed after ultrasonication. In the ultrasonicated dry digestion system (2 s per 30 s, 0.0025 W/mL), a 40% increase in the production of CH? was observed after lowering the total solid content of the reactor from 12% to 10%, implying that a high solid content diminished the ultrasonic stimulation effect. Moreover, the ultrasonication strength itself appeared to be a more crucial factor than the ultrasonication density during the application of LS-ultrasonication in the AD system. PMID:23582223

  13. Investigation of Non-Newtonian Flow in Anaerobic Digesters

    NASA Astrophysics Data System (ADS)

    Langner, Jeremy M.

    This thesis examines how the non-Newtonian characteristics of liquid hog manure affect the flow conditions within a steady-flow anaerobic digester. There are three main parts to this thesis. In the first part of this thesis, the physical properties of liquid hog manure and their variation with temperature and solids concentration are experimentally determined. Naturally-settled manure sampled from an outdoor storage lagoon is studied, and density, viscosity, and particle size distribution are measured. Hog manure with total solids concentrations of less than 3.6% exhibits Newtonian behaviour; manure between 3.6% and 6.5% total solids is pseudoplastic, and fits the power law; manure with more than 6.5% total solids exhibits non-Newtonian and time-dependent characteristics. The second part of this thesis investigates the flow of Newtonian and non-Newtonian fluids---represented by tap water and xanthan gum solution, respectively---within four lab-scale reactor geometries, using residence time distribution (RTD) experiments. The effect of reactor geometry, flow rate, and fluid viscosity are evaluated. In the third part of this thesis, flow conditions within lab-scale and pilot-scale anaerobic digester reactors are simulated using three-dimensional modeling techniques. The RTDs of lab-scale reactors as predicted by the 3D numerical models compare well to the experimental results. The 3D models are also validated using data from particle image velocimetry (PIV) experiments. Finally, the viscous properties of liquid hog manure at 3% and 8% total solids are incorporated into the models, and the results are evaluated.

  14. Anaerobic co-digestion of poultry blood with OFMSW: FTIR and TG-DTG study of process stabilization.

    PubMed

    Cuetos, M J; Morán, A; Otero, M; Gómez, X

    2009-05-01

    The potential of anaerobic digestion for the treatment of poultry blood has been evaluated in a co-digestion process. The organic fraction of municipal solid waste (OFMSW) was employed as the co-substrate to avoid digestion inhibition by dilution of nitrogen content and improvement of biodegradability. A semi-continuous mesophilic anaerobic digester was studied with a hydraulic retention time (HRT) of 36 days and an organic loading (OLR1) of 1.5 kg VSS feed m(-3) d(-1). The normal operational conditions of the reactor were altered with the application of an OLR2 of 2.0 kg VSS feed m(-3) d(-1) for a short period causing an imbalance in the process. The reduction of the OLR to initial conditions allowed the recovery of the system. The digestion process reached a final specific gas production (SGP) and a methane yield of 0.33 and 0.20 m3 kg(-1) VSS feed, respectively, maintaining low total and free ammonia concentrations. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to gain an insight into transformations experimented by the organic matter at the end of the stabilization process. Furthermore, these analytical techniques were used for evaluating the transformations undergone by the nitrogen-rich protein components of blood after digestion. It was proved that a reduction in volatile content and aliphatic structures of biowastes along with an increase in the degree of aromaticity occurred during the digestion process. PMID:19603704

  15. Life-Cycle Analysis of Energy and Greenhouse Gas Emissions from Anaerobic Biodegradation of Municipal Solid Waste

    Microsoft Academic Search

    Thomas D. DiStefano

    2009-01-01

    Energy requirements and greenhouse gas GHG emissions for current landfilling of municipal solid waste MSW was compared to potential biodegradation of MSW in anaerobic digesters AD throughout the United States. A hybrid life-cycle analysis was completed to assess the potential for anaerobic biodegradation of MSW to methane, a valuable energy source. Conversion of MSW to methane in AD would generate

  16. Mesophilic and thermophilic anaerobic digestion of biologically pretreated abattoir wastewaters in an upflow anaerobic filter.

    PubMed

    Gannoun, H; Bouallagui, H; Okbi, A; Sayadi, S; Hamdi, M

    2009-10-15

    The hydrolysis pretreatment of abattoir wastewaters (AW), rich in organic suspended solids (fats and protein) was studied in static and stirred batch reactors without aeration in the presence of natural microbial population acclimated in a storage tank of AW. Microbial analysis showed that the major populations which contribute to the pretreatment of AW belong to the genera Bacillus. Contrary to the static pretreatment, the stirred conditions favoured the hydrolysis and solubilization of 80% of suspended matter into soluble pollution. The pretreated AW, in continuous stirred tank reactor (CSTR) at a hydraulic retention time (HRT) of 2 days, was fed to an upflow anaerobic filter (UAF) at an HRT of 2 days. The performance of anaerobic digestion of biologically pretreated AW was examined under mesophilic (37 degrees C) and thermophilic (55 degrees C) conditions. The shifting from a mesophilic to a thermophilic environment in the UAF was carried out with a short start-up of thermophilic condition. The UAF ran at organic loading rates (OLRs) ranging from 0.9 to 6g COD/Ld in mesophilic conditions and at OLRs from 0.9 to 9 g COD/Ld in thermophilic conditions. COD removal efficiencies of 80-90% were achieved for OLRs up to 4.5 g COD/Ld in mesophilic conditions, while the highest OLRs i.e. 9 g COD/Ld led to efficiencies of 70-72% in thermophilic conditions. The biogas yield in thermophilic conditions was about 0.32-0.45 L biogas/g of COD removed for OLRs up to 4.5 g COD/Ld. For similar OLR, the UAF in mesophilic conditions showed lower percentage of methanization. Mesophilic anaerobic digestion has been shown to destroy pathogens partially, whereas the thermophilic process was more efficient in the removal of indicator microorganisms and pathogenic bacteria at different organic loading rates. PMID:19501962

  17. On-farm anaerobic digester and fuel-alcohol plant. Final report

    SciTech Connect

    Bengtson, H.H.

    1985-12-01

    An anaerobic-digestion system, coupled with a fuel-alcohol plant, was constructed and set up on a southern Illinois farm as part of an integrated farm-energy system. The digester heating can be done using waste hot water from the alcohol plant and biogas from the digester can be used as fuel for the alcohol production. The anaerobic digestion system is made up of the following components; a hog finishing house with a manure pit; a solids handling pump to feed the manure; and a 13,000-gallon railroad tank car as the main digester vessel and pump to transfer effluent from the digester to a 150,000 gallon storage tank. The digester was operated for sufficient time to demonstrate the use of hot water in an automated digester temperature control system. Sufficient biogas was produced to demonstrate the use of biogas in a converted propane boiler.

  18. Anaerobic digestion of autoclaved and untreated food waste.

    PubMed

    Tampio, Elina; Ervasti, Satu; Paavola, Teija; Heaven, Sonia; Banks, Charles; Rintala, Jukka

    2014-02-01

    Anaerobic digestion of autoclaved (160°C, 6.2 bar) and untreated source segregated food waste (FW) was compared over 473 days in semi-continuously fed mesophilic reactors with trace elements supplementation, at organic loading rates (OLRs) of 2, 3, 4 and 6 kg volatile solids(VS)/m(3)d. Methane yields at all OLR were 5-10% higher for untreated FW (maximum 0.483±0.013 m(3) CH4/kg VS at 3 kg VS/m(3) d) than autoclaved FW (maximum 0.439±0.020 m(3) CH4/kg VS at 4 kg VS/m(3) d). The residual methane potential of both digestates at all OLRs was less than 0.110 m(3) CH4/kg VS, indicating efficient methanation in all cases. Use of acclimated inoculum allowed very rapid increases in OLR. Reactors fed on autoclaved FW showed lower ammonium and hydrogen sulphide concentrations, probably due to reduced protein hydrolysis as a result of formation of Maillard compounds. In the current study this reduced biodegradability appears to outweigh any benefit due to thermal hydrolysis of ligno-cellulosic components. PMID:24238799

  19. Co-digestion of tobacco waste with different agricultural biomass feedstocks and the inhibition of tobacco viruses by anaerobic digestion.

    PubMed

    Liu, Yi; Dong, Jianxin; Liu, Gangjin; Yang, Hongnan; Liu, Wei; Wang, Lan; Kong, Chuixue; Zheng, Dan; Yang, Jinguang; Deng, Liangwei; Wang, Shusheng

    2015-08-01

    Tobacco is widely planted across the world especially in China, which means that a large amount of tobacco waste needs to be treated. This study investigated the biogas fermentation of tobacco stalks co-digested with different biomass feedstocks and the inactivation of Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV) by anaerobic digestion. Results showed that the maximum methane yield of tobacco stalks at 35°C was 0.163m(3)CH4?kgVS(-1), which was from the co-digestion of tobacco stalks, wheat stalks and pig manure. The largest VS removal rate of tobacco stalks was 59.10%. Proven by indicator paper stripe, half-leaf lesion and RT-PCR, CMV could be inactivated by mesophilic and thermophilic anaerobic digestion, whereas TMV could be only inactivated by thermophilic anaerobic digestion over 20days. These results suggested that using tobacco stalks as feedstock for anaerobic digestion and applying the digested residue and slurry to Solanaceae crop land are feasible. PMID:25898081

  20. Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process

    PubMed Central

    2010-01-01

    Background Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. Results Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%), based on the lower heating values, than the reference case (81%). Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L), including the reference case. Conclusions Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat. PMID:20843330

  1. Kinetics and advanced digester design for anaerobic digestion of water hyacinth and primary sludge

    SciTech Connect

    Chynoweth, D.P.; Dolenc, D.A.; Ghosh, S.; Henry, M.P.; Jerger, D.E.; Srivastava, V.J.

    1982-01-01

    A research program centered around a facility located at Walt Disney World (WDW) is in progress to evaluate the use of water hyacinth (WH) for secondary and tertiary wastewater treatment, to optimize growth of WH under these conditions, and to convert the resultant primary sludge (PS) and WH to methane via anaerobic digestion. This article describes the status of the biogasification component of this program, which includes baseline and advanced digestion experiments with individual feeds and blends and the design of an experimental test unit (ETU) to be installed at WDW. Experiments with several blends demonstrated that methane yields can be predicted from the fractional content and methane yield of each component. The process was found to adhere to the Monod kinetic model for microbial growth, and associated kinetic parameters were developed for various feed combinations. A novel upflow digester is achieving significantly higher conversion than a stirred-tank digester. Of several pretreatment techniques used, only alkaline treatment resulted in increased biodegradability. A larger scale (4.5 m/sup 3/) experimental test unit is being designed for installation at WDW in 1982. 13 figures, 4 tables.

  2. Study on anaerobic digestion treatment of hazardous colistin sulphate contained pharmaceutical sludge.

    PubMed

    Yin, Fubin; Wang, Dongling; Li, Zifu; Ohlsen, Thomas; Hartwig, Peter; Czekalla, Sven

    2015-02-01

    Pharmaceutical sludge is considered as a hazardous substance with high treatment and disposal fees. Anaerobic digestion could not only transform the hazardous substance into activated sludge, but also generate valuable biogas. This research had two objectives. First: studying the feasibility of anaerobic digestion and determining the biochemical methane potential (BMP) of pharmaceutical sludge under different Inoculum to substrate TS ratios (ISRs) of 0, 0.65, 2.58 and 10.32 in mesophilic condition of 37±1°C. Secondly, investigating the removal efficiency of colistin sulphate during anaerobic digestion. The results showed that the use of anaerobic digestion to treat the pharmaceutical sludge is feasible and that it can completely eliminate the colistin sulphate. The highest biogas production from pharmaceutical sludge is 499.46 mL/g TS at an ISR of 10.32. PMID:25490101

  3. Anaerobic Co-digestion of Chicken Processing Wastewater and Crude Glycerol from Biodiesel 

    E-print Network

    Foucault, Lucas Jose

    2011-10-21

    The main objective of this thesis was to study the anaerobic digestion (AD) of wastewater from a chicken processing facility and of crude glycerol from local biodiesel operations. The AD of these substrates was conducted in bench-scale reactors...

  4. Feasibility of a digester gas fuel production facility

    SciTech Connect

    Dakes, G.; Greene, D.S.; Sheehan, J.F.

    1982-03-01

    Results of studies on the feasibility of using digester gas produced from wastewater sludge to fuel vehicles are reported. Availability and suitability of digester gas as well as digester gas production records and test analyses on digester gas were reviewed. The feasibility of the project based on economic and environmental considerations is reported and compared to possible alternative uses of the digester gas.

  5. Anaerobic digestion of municipal solid waste as a treatment prior to landfill

    Microsoft Academic Search

    P. H. L. Nguyen; P. Kuruparan; C. Visvanathan

    2007-01-01

    Anaerobic digestion of organic fraction of municipal solid waste was conducted in pilot-scale reactor based on high-solid combined anaerobic digestion process. This study was performed in two runs. In Run 1 and Run 2, pre-stage flushing and micro-aeration were conducted to determine their effect in terms of enhancing hydrolysis and acidification in ambient condition. In Run 2, after pre-stage, the

  6. Improvement of activated sludge stabilisation and filterability during anaerobic digestion by fruit and vegetable waste addition

    Microsoft Academic Search

    Lahdheb Habiba; Bouallagui Hassib; Hamdi Moktar

    2009-01-01

    Anaerobic co-digestion of fruit and vegetable waste (FVW) and activated sludge (AS) was investigated using anaerobic sequencing batch reactors (ASBRs). The effects of AS:FVW ratio and the organic loading rate (OLR) on digesters performances were examined. The mixtures having AS:FVW ratios of 100:00, 65:35, 35:65, by a total solid (TS) basis were operated at an hydraulic retention time (HRT) of

  7. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition

    Microsoft Academic Search

    H. Bouallagui; H. Lahdheb; E. Ben Romdan; B. Rachdi; M. Hamdi

    2009-01-01

    The effect of fish waste (FW), abattoir wastewater (AW) and waste activated sludge (WAS) addition as co-substrates on the fruit and vegetable waste (FVW) anaerobic digestion performance was investigated under mesophilic conditions using four anaerobic sequencing batch reactors (ASBR) with the aim of finding the better co-substrate for the enhanced performance of co-digestion. The reactors were operated at an organic

  8. Enhancement of anaerobic digestion of waste activated sludge by alkaline solubilization

    Microsoft Academic Search

    Jih-Gaw Lin; Cheng-Nan Chang; Shou-Chung Chang

    1997-01-01

    The performance of an anaerobic digestion fed with waste activated sludge (WAS) pretreated with NaOH was examined. The sludge was periodically collected from a municipal wastewater-treatment plant. The laboratory work was run in four 1-l semi-continuous anaerobic digestion reactors. Reactor A was fed with untreated WAS at 1% total solids (TS). The other three reactors, B, C and D, were

  9. Integration of NIRS and PCA techniques for the process monitoring of a sewage sludge anaerobic digester.

    PubMed

    Reed, James P; Devlin, Desmond; Esteves, Sandra R R; Dinsdale, Richard; Guwy, Alan J

    2013-04-01

    This study investigates the use of Hotelling's T(2) control charts as the basis of a process monitor for sewage sludge anaerobic digestion. Fourier transform near infrared spectroscopy was used to produce partial least squares regression models of volatile fatty acids, bicarbonate alkalinity and volatile solids. These were utilised in a series of principle component analysis models along with spectral data from digestate and feedstock samples to produce a pseudo steady state model, which was then used with an independent test set to evaluate the system. The system was able to identify disturbances to the digester due to a temporary alteration of the type of feedstock to the digester and separately, halving of the hydraulic retention time of the digester. It could also provide advance warning of disturbances to the digester. This technique could be used to improve the performance of sewage sludge anaerobic digesters by enabling optimisation of the process. PMID:23454801

  10. Anaerobic digestibility of the waste activated sludge discharged from large-scale membrane bioreactors.

    PubMed

    Yu, Zhiyong; Wen, Xianghua; Xu, Meilan; Qi, Meng; Huang, Xia

    2012-12-01

    Anaerobic digestibility of the waste activated sludge (WAS) discharged from large-scale membrane bioreactors (MBRs) and conventional activated sludge processes (CASs) were compared using batch trials. Four wastewater treatment plants were sampled. Results showed that the sludge from MBRs had poor anaerobic digestibility as it had lower volatile solid (VS) reduction rate and lower maximum biogas production rate. The partial sludge stabilization during the long sludge retention time (SRT) typically applied in MBRs was the possible reason. On the other hand, the difference in wastewater composition had a great impact on the properties of activated sludge and the downstream sludge digestion. Inorganic matter accumulation in the WAS may hinder the access of microorganisms to substrate. The humic-like substances accumulating in the activated sludge was expected to contribute to the worse digestibility and these substances were observed to be released during anaerobic digestion through three-dimensional excitation-emission matrix (EEM) fluorescence spectra. PMID:23131311

  11. Measuring anaerobic sludge digestion and growth by a simple alkalimetric titration

    SciTech Connect

    Jenkins, S.R.; Morgan, J.M.; Sawyer, C.L.

    1983-05-01

    Organic acids produced in the anaerobic digestion of waste-water sludges tend continuously to depress pH below a point where the acids can be converted to methane. As a result, a large buffering capacity is required to maintain pH between 6.7 and 7.4, which allows efficient operation. Present tests to measure this buffer capacity are inadequate. The present research proposes a simple but adequate test that will provide plant operators with accurate information on anaerobic digester efficiency, as well as considerable long-range insight into digester operation - it would seem that an alkalimetric titration to pH 5.75 can be used routinely to monitor laboratory and actual anaerobic digester performance with a high degree of confidence. The simplicity of the test should encourage many operators to pay more attention to digester performance and, therefore, result in improved waste water treatment efficiency. (Refs. 7).

  12. Sulfate reduction, nutrient limitation, and reactor design considerations in anaerobic digesters

    Microsoft Academic Search

    1991-01-01

    Three areas of improvement in anaerobic digestion were investigated: inhibition of sulfate reduction, nutrient limitation, and reactor design. In the anaerobic treatment of wastewaters containing high concentrations of sulfate, hydrogen sulfide, an undesirable end product, is produced by sulfate reducing bacteria (SRB). Research was conducted to evaluate the feasibility of adding SRB-specific biochemical inhibitors to a waste stream as a

  13. Feasibility study of the anaerobic digestion of dewatered pig slurry by means of polyacrylamide

    Microsoft Academic Search

    E. Campos; M. Almirall; J. Mtnez-Almela; J. Palatsi; X. Flotats

    2007-01-01

    Liquid livestock waste can be managed by separating liquid and solid fractions then treating each separately by applying best avail- able technology, such as anaerobic digestion for the solid fraction. There is an increasing use of polyacrylamide (PAM) as a flocculant agent to improve solid-liquid separation. In the present work, the anaerobic toxicity of PAM residues and the optimal range

  14. Feasibility study of the anaerobic digestion of dewatered pig slurry by means of polyacrylamide

    Microsoft Academic Search

    E. Campos; M. Almirall; J. Mtnez-Almela; J. Palatsi; X. Flotats

    2008-01-01

    Liquid livestock waste can be managed by separating liquid and solid fractions then treating each separately by applying best available technology, such as anaerobic digestion for the solid fraction. There is an increasing use of polyacrylamide (PAM) as a flocculant agent to improve solid–liquid separation. In the present work, the anaerobic toxicity of PAM residues and the optimal range of

  15. Anaerobic digestion of wood ethanol stillage using upflow anaerobic sludge blanket reactor

    SciTech Connect

    Callander, I.J.; Clark, T.A.; McFarlane, P.N.

    1987-01-01

    The anaerobic digestion of wood ethanol stillage in a UASB reactor was studied. At organic loading rates below 16 kg COD/m/sup 3/ day the reactor performed effectively, achieving soluble COD and BOD removals in excess of 86 and 93%, respectively. Removal of color averaged 40%. At a loading rate of 16 kg COD/m/sup 3/ day the methane yield was 0.302 L CH/sub 4/ (STP)/g COD removed, and the observed cell yield was 0.112 g VSS/g COD removed. Operation of the reactor at higher loading rates was unsuccessful. Nitrogen, phosphorus, and alkalinity were supplemented. No additions of the essential trace elements Fe, Co, and Ni were required.

  16. A hybrid anaerobic solid-liquid bioreactor for food waste digestion

    Microsoft Academic Search

    Xu Hai-Lou; Wang Jing-Yuan; Tay Joo-Hwa

    2002-01-01

    A hybrid anaerobic solid-liquid (HASL) bioreactor is an enhanced two-phase anaerobic system, that consists of a solid waste reactor as the acidification reactor and a wastewater reactor, i.e. an upflow anaerobic sludge blanket (UASB) reactor as the methanogenic reactor. Food waste digestion in HASL bioreactors with pre-acidification and HASL operation stages was investigated in two separate runs. After 8 days

  17. Biodegradability and change of physical characteristics of particles during anaerobic digestion of domestic sewage

    Microsoft Academic Search

    Tarek A Elmitwalli; Jesko Soellner; Arie De Keizer; Harry Bruning; Grietje Zeeman; Gatze Lettinga

    2001-01-01

    At the high-rate anaerobic treatment of domestic sewage, both biological and physical processes play an important role. Therefore, the anaerobic biodegradability of raw, paper-filtered and membrane-filtered sewage and black water has been investigated in batch experiments. Additionally, the effect of anaerobic digestion on physical characteristics, like particle size, surface tension and zeta-potential, of the present particles is studied. The biodegradability

  18. Supercritical Fluid Extraction of Bacterial and Archaeal Lipid Biomarkers from Anaerobically Digested Sludge

    PubMed Central

    Hanif, Muhammad; Atsuta, Yoichi; Fujie, Koichi; Daimon, Hiroyuki

    2012-01-01

    Supercritical fluid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. Bacterial RQ were determined using ultra performance liquid chromatography (UPLC). Determination of bacterial PLFA and archaeal PLEL was simultaneously performed using gas chromatography-mass spectrometry (GC-MS). The effects of pressure, temperature, and modifier concentration on the total amounts of RQ, PLFA, and PLEL were investigated by 23 experiments with five settings chosen for each variable. The optimal extraction conditions that were obtained through a multiple-response optimization included a pressure of 23.6 MPa, temperature of 77.6 °C, and 10.6% (v/v) of methanol as the modifier. Thirty nine components of microbial lipid biomarkers were identified in the anaerobically digested sludge. Overall, the SFE method proved to be more effective, rapid, and quantitative for simultaneously extracting bacterial and archaeal lipid biomarkers, compared to conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile. PMID:22489140

  19. Mechanisms of floc destruction during anaerobic and aerobic digestion and the effect on conditioning and dewatering of biosolids

    Microsoft Academic Search

    John T. Novak; Mary E. Sadler; Sudhir N. Murthy

    2003-01-01

    Laboratory anaerobic and aerobic digestion studies were conducted using waste activated sludges from two municipal wastewater treatment plants in order to gain insight into the mechanisms of floc destruction that account for changes in sludge conditioning and dewatering properties when sludges undergo anaerobic and aerobic digestion. Batch digestion studies were conducted at 20°C and the dewatering properties, solution biopolymer concentration

  20. Mesophilic and thermophilic anaerobic digestion of primary and secondary sludge. Effect of pre-treatment at elevated temperature

    Microsoft Academic Search

    Hariklia N. Gavala; Umur Yenal; Ioannis V. Skiadas; Peter Westermann; Birgitte K. Ahring

    2003-01-01

    Anaerobic digestion is an appropriate technique for the treatment of sludge before final disposal and it is employed worldwide as the oldest and most important process for sludge stabilization. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization, enhancement of dewatering of the

  1. Modeling the anaerobic digestion of cane-molasses vinasse: extension of the Anaerobic Digestion Model No. 1 (ADM1) with sulfate reduction for a very high strength and sulfate rich wastewater.

    PubMed

    Barrera, Ernesto L; Spanjers, Henri; Solon, Kimberly; Amerlinck, Youri; Nopens, Ingmar; Dewulf, Jo

    2015-03-15

    This research presents the modeling of the anaerobic digestion of cane-molasses vinasse, hereby extending the Anaerobic Digestion Model No. 1 with sulfate reduction for a very high strength and sulfate rich wastewater. Based on a sensitivity analysis, four parameters of the original ADM1 and all sulfate reduction parameters were calibrated. Although some deviations were observed between model predictions and experimental values, it was shown that sulfates, total aqueous sulfide, free sulfides, methane, carbon dioxide and sulfide in the gas phase, gas flow, propionic and acetic acids, chemical oxygen demand (COD), and pH were accurately predicted during model validation. The model showed high (±10%) to medium (10%-30%) accuracy predictions with a mean absolute relative error ranging from 1% to 26%, and was able to predict failure of methanogenesis and sulfidogenesis when the sulfate loading rate increased. Therefore, the kinetic parameters and the model structure proposed in this work can be considered as valid for the sulfate reduction process in the anaerobic digestion of cane-molasses vinasse when sulfate and organic loading rates range from 0.36 to 1.57 kg [Formula: see text]  m(-3) d(-1) and from 7.66 to 12 kg COD m(-3) d(-1), respectively. PMID:25589435

  2. ENERGY AND ECONOMIC ASSESSMENT OF ANAEROBIC DIGESTERS AND BIOFUELS FOR RURAL WASTE MANAGEMENT

    EPA Science Inventory

    A technological and socioeconomic assessment of anaerobic digester feasibility for small to mid-size livestock operations was undertaken. Three full scale digesters and one pilot scale facility were under various degrees of monitoring and evaluation to assess design and operation...

  3. Removal of helminth eggs and fecal coliforms by anaerobic thermophilic sludge digestion

    Microsoft Academic Search

    N. Cabirol; M. Rojas Oropeza; A. Noyola

    Anaerobic digestion of two types of waste sludge was applied in order to assess the suitability of thermophilic conditions for the stabilization of organic matter and removal of fecal coliforms and helminth eggs. Feeding sludge was taken from an activated sludge municipal facility (BS) and from an enhanced primary treatment municipal plant (EPT). As an accompanying experiment, mesophilic digesters were

  4. Biochar produced from anaerobically-digested fiber reduces phosphorus in dairy lagoons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the use of biochar produced from anaerobic digester dairy fiber (ADF) to sequester phosphorus from dairy lagoons. The ADF was collected from a plugged flow digester, air dried to < 8% water content, and pelletized. Biochar was produced by slow pyrolysis in a barrel retort. The potential...

  5. Biogas production from different substrates in an experimental Continuously Stirred Tank Reactor anaerobic digester

    Microsoft Academic Search

    Francesco Fantozzi; Cinzia Buratti

    2009-01-01

    Different mixtures were digested in a single-stage, batch, mixed, laboratory scale mesophilic anaerobic digester at the Biomass Research Centre Laboratory (University of Perugia). The yield and the composition of biogas from the different substrates were evaluated and the cumulative curves were estimated. Two experimental campaigns were carried out, the first on three mixtures (chicken, pig and bovine manures), the second

  6. COMPARATIVE EVALUATION OF MESOPHILIC AND THERMOPHILIC ANAEROBIC DIGESTION. PHASE 2. STEADY STATE STUDIES

    EPA Science Inventory

    A study was conducted of the relative performance of anaerobic digestion systems under mesophilic and thermophilic conditions. Fifty liter laboratory scale digesters were fed primary sludge from the Allentown, PA Waste Water Treatment Plant. Long-term, steady-state performance da...

  7. The future of anaerobic digestion and biogas utilization.

    PubMed

    Holm-Nielsen, J B; Al Seadi, T; Oleskowicz-Popiel, P

    2009-11-01

    One of the common tendencies of animal production activities in Europe and in developed countries in general is to intensify the animal production and to increase the size of the animal production units. High livestock density is always accompanied by production of a surplus of animal manure, representing a considerable pollution threat for the environment in these areas. Avoiding over-fertilization is not only important for environmental protection reasons but also for economical reasons. Intensive animal production areas need therefore suitable manure management, aiming to export and to redistribute the excess of nutrients from manure and to optimize their recycling. Anaerobic digestion of animal manure and slurries offers several benefits by improving their fertilizer qualities, reducing odors and pathogens and producing a renewable fuel - the biogas. The EU policies concerning renewable energy systems (RES) have set forward a fixed goal of supplying 20% of the European energy demands from RES by year 2020. A major part of the renewable energy will originate from European farming and forestry. At least 25% of all bioenergy in the future can originate from biogas, produced from wet organic materials such as: animal manure, whole crop silages, wet food and feed wastes, etc. PMID:19217772

  8. An examination of the effects of detergents on anaerobic digestion.

    PubMed

    Mensah, Kojo Arthur; Forster, Christopher F

    2003-11-01

    An anaerobic filter was used to examine the treatability of wastewater formulated to simulate that from the manufacture of detergents. The detergent element was a mixture (1:1:1 v/v) of concentrated washing up liquid, a non-biological hand washing detergent and a fabric softener and, thus contained a combination of cationic surfactants, anionic surfactants, non-ionic surfactants and amphoteric surfactants. A concentration of 2 ml/l caused a deterioration in the performance of the digester which was pronounced after 7 days. When the packing of the filter was modified to include two layers of granular activated carbon, 320 g in total, the reactor was capable of treating a feed containing 10 ml/l. The amount of detergent removed during this second trial was greater than the Langmuir monolayer capacity of the carbon, indicating that both adsorption and degradation were occurring. The results also showed that, at detergent concentrations greater than 1 ml/l, the theoretical COD removal was lower than the actual COD removal. This was compatible with there being an element of adsorption by the activated carbon. PMID:12895555

  9. The environmental sustainability of anaerobic digestion as a biomass valorization technology.

    PubMed

    De Meester, Steven; Demeyer, Jens; Velghe, Filip; Peene, Andy; Van Langenhove, Herman; Dewulf, Jo

    2012-10-01

    This paper studies the environmental sustainability of anaerobic digestion from three perspectives. First, reference electricity is compared to electricity production from domestic organic waste and energy crop digestion. Second, different digester feed possibilities in an agricultural context are studied. Third, the influence of applying digestate as fertilizer is investigated. Results highlight that biomass is converted at a rational exergy (energy) efficiency ranging from 15.3% (22.6) to 33.3% (36.0). From a life cycle perspective, a saving of over 90% resources is achieved in most categories when comparing biobased electricity to conventional electricity. However, operation without heat valorization results in 32% loss of this performance while using organic waste (domestic and agricultural residues) as feedstock avoids land resources. The use of digestate as a fertilizer is beneficial from a resource perspective, but causes increased nitrogen and methane emissions, which can be reduced by 50%, making anaerobic digestion an environmentally competitive bioenergy technology. PMID:22864176

  10. Greenhouse and laboratory studies on the effects of an anaerobic digester sludge on growth and nutrient uptake of sorghum 

    E-print Network

    Vincent, John Cooper

    1989-01-01

    potentials (N0), and percent N recovery from anaerobic sorghum digester sludge, experiment 1. . 37 Interactive effect of sorghum anaerobic digester sludge and N fertilizer on sorghum dry matter yield, experiment 2, harvest 1. . . 45 Effect of sorghum..., harvest 3, experiment 3 Apparent recovery of sludge and fertilizer applied P, experiment 3. Effect of anaerobic sorghum digester sludge on residual soil P following harvest 3, experiment 3 . 74 . 79 F 80 . 83 . 84 Effect of fertilizer P...

  11. Modelling start-up performance of anaerobic digestion of saline-rich macro-algae.

    PubMed

    Hierholtzer, A; Akunna, J C

    2014-01-01

    Some of the key factors affecting the adaptation of anaerobic digestion processes to increasing levels of salinity were determined in batch tests using brown seaweed as a feedstock. It was found that cultures seeded with non-saline anaerobic inoculum required an adaptation period of up to two months to reach the same level of methane production rate as in those cultures seeded with saline-adapted inoculum. The Anaerobic Digestion Model No.1 (ADM1) was modified to include an extra inhibition function to account for the effect of salinity, and calibrated using a set of experimental data obtained from batch biochemical methane potential tests. After calibration, the model was able to accurately predict methane production rates. Thus, the results show that, in the absence of saline-adapted inoculum, non-saline inoculum can be used for the start-up of anaerobic digestion systems treating saline-rich feedstocks. PMID:24845321

  12. Effect of anaerobic digestion on oocysts of the protozoan Eimeria tenella.

    PubMed Central

    Lee, M R; Shih, J C

    1988-01-01

    The effect of anaerobic digestion of poultry waste on oocysts of the protozoan Eimeria tenella, a common enteric pathogen that causes coccidiosis in poultry, was investigated in this study. Thermophilic (50 degrees C) and mesophilic (35 degrees C) anaerobic digestors, with poultry manure as the substrate, were inoculated with the oocysts. The oocysts were damaged during anaerobic digestion, as determined by morphological change and loss of their ability to sporulate. The recovered oocysts were tested for their infectivity in young chicks, as measured by body weight gain, mortality, and cecal lesions. Oocysts lost all their infectivity during thermophilic digestion, while oocysts subjected to mesophilic digestion remained moderately infective in comparison with untreated oocysts, which produced severe coccidiosis, high mortality, and low body weight gain in chicks. Oocysts were inactivated at 50 degrees C when they were suspended in digestor fluid or saline. Inactivation at 35 degrees C was significantly stronger in the digestor fluid than in the saline, which implied that factors other than temperature were involved in the lethal effect of anaerobic digestion on protozoan oocysts. In this study we demonstrated that the treatment of animal waste by anaerobic digestion, especially at a thermophilic temperature, has the benefits of pathogen control and protection of human and animal health in a farm environment. Images PMID:3202626

  13. Effect of anaerobic digestion on oocysts of the protozoan Eimeria tenella.

    PubMed

    Lee, M R; Shih, J C

    1988-10-01

    The effect of anaerobic digestion of poultry waste on oocysts of the protozoan Eimeria tenella, a common enteric pathogen that causes coccidiosis in poultry, was investigated in this study. Thermophilic (50 degrees C) and mesophilic (35 degrees C) anaerobic digestors, with poultry manure as the substrate, were inoculated with the oocysts. The oocysts were damaged during anaerobic digestion, as determined by morphological change and loss of their ability to sporulate. The recovered oocysts were tested for their infectivity in young chicks, as measured by body weight gain, mortality, and cecal lesions. Oocysts lost all their infectivity during thermophilic digestion, while oocysts subjected to mesophilic digestion remained moderately infective in comparison with untreated oocysts, which produced severe coccidiosis, high mortality, and low body weight gain in chicks. Oocysts were inactivated at 50 degrees C when they were suspended in digestor fluid or saline. Inactivation at 35 degrees C was significantly stronger in the digestor fluid than in the saline, which implied that factors other than temperature were involved in the lethal effect of anaerobic digestion on protozoan oocysts. In this study we demonstrated that the treatment of animal waste by anaerobic digestion, especially at a thermophilic temperature, has the benefits of pathogen control and protection of human and animal health in a farm environment. PMID:3202626

  14. Rapid establishment of thermophilic anaerobic microbial community during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester.

    PubMed

    Tian, Zhe; Zhang, Yu; Li, Yuyou; Chi, Yongzhi; Yang, Min

    2015-02-01

    The purpose of this study was to explore how fast the thermophilic anaerobic microbial community could be established during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester. Stable thermophilic anaerobic digestion was achieved within 20 days from a mesophilic digester treating sewage sludge by adopting the one-step startup strategy. The succession of archaeal and bacterial populations over a period of 60 days after the temperature increment was followed by using 454-pyrosequencing and quantitative PCR. After the increase of temperature, thermophilic methanogenic community was established within 11 days, which was characterized by the fast colonization of Methanosarcina thermophila and two hydrogenotrophic methanogens (Methanothermobacter spp. and Methanoculleus spp.). At the same time, the bacterial community was dominated by Fervidobacterium, whose relative abundance rapidly increased from 0 to 28.52 % in 18 days, followed by other potential thermophilic genera, such as Clostridium, Coprothermobacter, Anaerobaculum and EM3. The above result demonstrated that the one-step startup strategy could allow the rapid establishment of the thermophilic anaerobic microbial community. PMID:25463927

  15. Aeration of anaerobically digested sewage sludge for COD and nitrogen removal: optimization at large-scale.

    PubMed

    Parravicini, V; Svardal, K; Hornek, R; Kroiss, H

    2008-01-01

    The paper will report about the experiences at an Austrian large wastewater treatment plant of 720,000 population equivalents, where anaerobically digested sewage sludge is further stabilised under aerobic conditions. Enhanced stabilisation of the anaerobically digested sludge was required at the plant in order to get a permit for landfill disposal of the dewatered stabilized sludge. By implementing a post-aeration treatment (SRT approximately 6d; 36 degrees C) after anaerobic digestion the organic content of the anaerobically well digested sludge can be decreased by 16%. Investigations on site showed that during digested sludge post-aeration anoxic phases for denitrification are needed to provide stable process conditions. In this way the pH value can be kept in a more favourable range for micro-organisms and concrete structures. Additionally, inhibition of the biological process due to nitrite accumulation can be avoided. By optimising the aeration/pause ratio approximately 45% of total nitrogen in digested sludge can be removed. This significantly improves nitrogen removal efficiency at the wastewater treatment plant. NH(4)-removal occurs mainly through nitritation and denitritation with an efficiency of 98%. The costs/benefit analysis shows that post-aeration of digested sludge results in an increase of total annual costs for wastewater treatment of only 0.84%, corresponding to 0.19 Euro/pe/a. Result of molecular biological analyses (DGGE) indicate that all four ammonium-oxidizing bacteria species present in activated sludge can survive anaerobic digestion, but only two of them can adapt in the digested sludge post-aeration tanks. Additionally, in the post-aerated digested sludge a further ammonium-oxidizing bacteria species was identified. PMID:18235180

  16. Evaluation of a microwave-heating anaerobic digester treating municipal secondary sludge.

    PubMed

    Jang, Joo-Hyun; Ahn, Johng-Hwa

    2013-01-01

    This work experimentally determined the effect of microwave irradiation on the anaerobic digestion of municipal secondary sludge in semi-continuous mesophilic digesters at hydraulic retention times (HRT) of 15, 10 and 5 days when microwaves were used as a heating source. A microwave-heating anaerobic digester (MHAD) was compared with a water-heating reactor (control). Biogas production increased in both digesters as the HRT decreased except for the control with a HRT of 5 days. Improvement in removal efficiency of volatile solid and biogas production of the MHAD relative to the control increased as the HRT decreased. The results show that the MHAD was more effective than the control in increasing mesophilic anaerobic biodegradability and biogas production treating secondary sludge. PMID:23837339

  17. [Effect of substrate concentration on pathogen indicators inactivation during thermophilic anaerobic digestion].

    PubMed

    Cao, Hong-Qing; Zhang, Fei-Fei; Li, Jian; Tong, Zi-Lin; Hu, Zhen-Hu

    2014-03-01

    Because excess sludge contains high density of pathogens, it has to be treated to reduce pathogens before being disposed for land application. In this study, the effect of substrate concentration on pathogen inactivation during thermophilic anaerobic digestion was investigated. The results show that, with the increase of substrate concentration, VFAs and cumulative methane production increased. The density of total coliforms in the suspension liquid has a 2.0-3.0 orders of magnitude decline and fecal coliforms has 1.8-3.3 orders of magnitude decline after 28 days thermophilic anaerobic digestion at substrate concentration of 28-84 g x L(-1) and temperature of 55 degrees C. More than 99% of total coliforms and fecal coliforms have been killed after 28 days digestion. Salmonella spp. was not detected in the suspension and solid after anaerobic digestion. When substrate concentration was higher than 45 g x L(-1), the inactivation of total coliforms and fecal coliforms declined. PMID:24881391

  18. Assessment of the potential for biogas production from wheat straw leachate in upflow anaerobic sludge blanket digesters.

    PubMed

    Idrus, S; Banks, C J; Heaven, S

    2012-01-01

    Wheat straw is a major potential source of waste biomass for renewable energy production, but its high salt content causes problems in combustion. The salts can be removed by washing, but this process also removes a proportion of the organic material which could potentially be recovered by anaerobic digestion of the washwater leachate. This approach would maximise the overall energy yield in an integrated process in which washwater could be recycled after further desalting. Leachate from cold water washing with a chemical oxygen demand (COD) of 1.2 g l?¹ was fed to mesophilic upflow anaerobic sludge blanket (UASB) digesters at a loading rate of 1 g COD l?¹ day?¹ to determine the energy yield and any detrimental effects of the leached salts on the process. The specific methane production was 0.29 l CH? g?¹ COD(added), corresponding to a COD removal rate of 84%. Light metal cations in the leachate, especially potassium, were found to accumulate in the digesters and appeared to have a synergistic effect up to a concentration of ?6.5 mg K g?¹ wet weight of the granular sludge, but further accumulation caused inhibition of methanogenesis. It was shown that gas production in the inhibited digesters could be restored within 12 days by switching the feed to a synthetic sewage, which washed the accumulated K out of the digesters. PMID:23109593

  19. Feasibility and interest of the anammox process as treatment alternative for anaerobic digester supernatants in manure processing--an overview.

    PubMed

    Magrí, Albert; Béline, Fabrice; Dabert, Patrick

    2013-12-15

    Completely autotrophic nitrogen removal (ANR) is based on the combination of partial nitritation (PN) and anaerobic ammonium oxidation (anammox). It is a promising alternative for the subsequent treatment of biogas digester supernatants in livestock manure processing and nitrogen surplus scenarios. However, as no full-scale experiences in the treatment of manure digestates by ANR have been published to date, future field studies addressing treatment of this kind of effluent would be of great interest. Some topics to be considered in these studies would be coupling anaerobic digestion and ANR, analysis of the factors that affect the process, comparing reactor configurations, microbial ecology, gas emissions, and achieving robust performance. This paper provides an overview of published studies on ANR. Specific issues related to the applicability of the process for treating manure digestates are discussed. The energy requirements of ANR are compared with those of other technological alternatives aimed at recovering nitrogen from digester supernatants. The results of the assessment were shown to depend on the composition of the supernatant. In this regard, the PN-anammox process was shown to be more competitive than other alternatives particularly at concentrations of up to 2 kg NH4(+)-N m(-3). PMID:24161806

  20. Thermal wet oxidation improves anaerobic biodegradability of raw and digested biowaste.

    PubMed

    Lissens, Geert; Thomsen, Anne Belinda; De Baere, Luc; Verstraete, Willy; Ahring, Birgitte K

    2004-06-15

    Anaerobic digestion of solid biowaste generally results in relatively low methane yields of 50-60% of the theoretical maximum. Increased methane recovery from organic waste would lead to reduced handling of digested solids, lower methane emissions to the environment, and higher green energy profits. The objective of this research was to enhance the anaerobic biodegradability and methane yields from different biowastes (food waste, yard waste, and digested biowaste already treated in a full-scale biogas plant (DRANCO, Belgium)) by assessing thermal wet oxidation. The biodegradability of the waste was evaluated by using biochemical methane potential assays and continuous 3-L methane reactors. Wet oxidation temperature and oxygen pressure (T, 185-220 degrees C; O2 pressure, 0-12 bar; t, 15 min) were varied for their effect on total methane yield and digestion kinetics of digested biowaste. Measured methane yields for raw yard waste, wet oxidized yard waste, raw food waste, and wet oxidized food waste were 345, 685, 536, and 571 mL of CH/g of volatile suspended solids, respectively. Higher oxygen pressure during wet oxidation of digested biowaste considerably increased the total methane yield and digestion kinetics and permitted lignin utilization during a subsequent second digestion. The increase of the specific methane yield for the full-scale biogas plant by applying thermal wet oxidation was 35-40%, showing that there is still a considerable amount of methane that can be harvested from anaerobic digested biowaste. PMID:15260343

  1. Evaluation of biogas production potential by dry anaerobic digestion of switchgrass--animal manure mixtures.

    PubMed

    Ahn, H K; Smith, M C; Kondrad, S L; White, J W

    2010-02-01

    Anaerobic digestion is a biological method used to convert organic wastes into a stable product for land application with reduced environmental impacts. The biogas produced can be used as an alternative renewable energy source. Dry anaerobic digestion [>15% total solid (TS)] has an advantage over wet digestion (<10% TS) because it allows for the use of a smaller volume of reactor and because it reduces wastewater production. In addition, it produces a fertilizer that is easier to transport. Performance of anaerobic digestion of animal manure-switchgrass mixture was evaluated under dry (15% TS) and thermophilic conditions (55 degrees C). Three different mixtures of animal manure (swine, poultry, and dairy) and switchgrass were digested using batch-operated 1-L reactors. The swine manure test units showed 52.9% volatile solids (VS) removal during the 62-day trial, while dairy and poultry manure test units showed 9.3% and 20.2%, respectively. Over the 62 day digestion, the swine manure test units yielded the highest amount of methane 0.337 L CH4/g VS, while the dairy and poultry manure test units showed very poor methane yield 0.028 L CH4/g VS and 0.002 L CH4/g VS, respectively. Although dairy and poultry manure performed poorly, they may still have high potential as biomass for dry anaerobic digestion if appropriate designs are developed to prevent significant volatile fatty acid (VFA) accumulation and pH drop. PMID:19462259

  2. Sequential anaerobic/anaerobic digestion for enhanced sludge stabilization: comparison of the process performance for mixed and waste sludge.

    PubMed

    Tomei, M Concetta; Carozza, Nicola Antonello

    2015-05-01

    Sequential anaerobic-aerobic digestion has been demonstrated as a promising alternative for enhanced sludge stabilization. In this paper, a feasibility study of the sequential digestion applied to real waste activated sludge (WAS) and mixed sludge is presented. Process performance is evaluated in terms of total solid (TS) and volatile solid (VS) removal, biogas production, and dewaterability trend in the anaerobic and double-stage digested sludge. In the proposed digestion lay out, the aerobic stage was operated with intermittent aeration to reduce the nitrogen load recycled to the wastewater treatment plant (WWTP). Experimental results showed a very good performance of the sequential digestion process for both waste and mixed sludge, even if, given its better digestibility, higher efficiencies are observed for mixed sludge. VS removal efficiencies in the anaerobic stage were 48 and 50 % for waste and mixed sludge, respectively, while a significant additional improvement of the VS removal of 25 % for WAS and 45 % for mixed sludge has been obtained in the aerobic stage. The post-aerobic stage, operated with intermittent aeration, was also efficient in nitrogen removal, providing a significant decrease of the nitrogen content in the supernatant: nitrification efficiencies of 90 and 97 % and denitrification efficiencies of 62 and 70 % have been obtained for secondary and mixed sludges, respectively. A positive effect due to the aerobic stage was also observed on the sludge dewaterability in both cases. Biogas production, expressed as Nm(3)/(kgVSdestroyed), was 0.54 for waste and 0.82 for mixed sludge and is in the range of values reported in the literature in spite of the low anaerobic sludge retention time of 15 days. PMID:25028317

  3. Increasing biogas production from sewage sludge anaerobic co-digestion process by adding crude glycerol from biodiesel industry.

    PubMed

    Nartker, Steven; Ammerman, Michelle; Aurandt, Jennifer; Stogsdil, Michael; Hayden, Olivia; Antle, Chad

    2014-12-01

    In an effort to convert waste streams to energy in a green process, glycerol from biodiesel manufacturing has been used to increase the gas production and methane content of biogas within a mesophilic anaerobic co-digestion process using primary sewage sludge. Glycerol was systematically added to the primary digester from 0% to 60% of the organic loading rate (OLR). The optimum glycerol loading range was from 25% to 60% OLR. This resulted in an 82-280% improvement in specific gas production. Following the feeding schedule described, the digesters remained balanced and healthy until inhibition was achieved at 70% glycerol OLR. This suggests that high glycerol loadings are possible if slow additions are upheld in order to allow the bacterial community to adjust properly. Waste water treatment plant operators with anaerobic digesters can use the data to increase loadings and boost biogas production to enhance energy conversion. This process provides a safe, environmentally friendly method to convert a typical waste stream to an energy stream of biogas. PMID:25249492

  4. The effects of sludge rheology on mixing in the anaerobic digestion process

    SciTech Connect

    Baxter, T.E.

    1988-01-01

    A review of the literature indicated that the understanding of the mixing process in anaerobic digesters is limited. Also indicated was the fact that the ability to measure digester mixing characteristics was lacking and that the rheological characteristics of the sludge have been largely ignored. The need for a more thorough understanding of fundamental mixing relationships and the ability to measure these relationships in the anaerobic digester was recognized. The measurement of mixing characteristics in two laboratory-scale, impeller mixed, anaerobic digesters was based on the concepts of Circulation Time Distribution theory. Circulation time was measured directly from a continuous recording of the change in conductivity following a pulse injection of an ionic tracer. Mean circulation time values were used to derive impeller discharge and pumping flow rates. Impeller flow rates were determined in water and in digesting sludge for comparison. The determination of digesting sludge rheological properties was based on a simple viscometric method, using a Brookfield Model RVT viscometer. The viscometer data were converted to shear stress and shear rate values using conversion factors obtained from the literature. Viscosity functions were derived for the digesting sludge at various levels of total suspended solids. Tests for thixotropy were also conducted on the digesting sludge. The results of this study indicated that the rheological properties of digesting sludge have significant effects on the anaerobic digester mixing process. The Circulation Time Distribution method provided the ability to detect these effects. Additional studies are needed to extend the use of the CTD method and to better define its potential as a tool for designing digester mixing systems.

  5. Relationship between anaerobic digestion of biodegradable solid waste and spectral characteristics of the derived liquid digestate.

    PubMed

    Zheng, Wei; Lü, Fan; Phoungthong, Khamphe; He, Pinjing

    2014-06-01

    The evolution of spectral properties during anaerobic digestion (AD) of 29 types of biodegradable solid waste was investigated to determine if spectral characteristics could be used for assessment of biological stabilization during AD. Biochemical methane potential tests were conducted and spectral indicators (including the ratio of ultraviolet-visible absorbance at 254nm to dissolved organic carbon concentration (SUVA254), the ratio of ultraviolet-visible absorbance measured at 465nm and 665nm (E4/E6), and the abundance of fluorescence peaks) were measured at different AD phases. Inter-relationship between organic degradation and spectral indicators were analyzed by principle component analysis. The results shows that from methane production phase to the end of methane production phase, SUVA254 increased by 0.16-10.93 times, the abundance of fulvic acid-like compounds fluorescence peak increased by 0.01-0.54 times, the abundance of tyrosine fluorescence peak decreased by 0.03-0.64 times. Therefore, these indicators were useful to judge the course of mixed waste digestion. PMID:24686373

  6. Growth of Chlorella vulgaris on sugarcane vinasse: the effect of anaerobic digestion pretreatment.

    PubMed

    Marques, Sheyla Santa Isabel; Nascimento, Iracema Andrade; de Almeida, Paulo Fernando; Chinalia, Fábio Alexandre

    2013-12-01

    Microalgae farming has been identified as the most eco-sustainable solution for producing biodiesel. However, the operation of full-scale plants is still limited by costs and the utilization of industrial and/or domestic wastes can significantly improve economic profits. Several waste effluents are valuable sources of nutrients for the cultivation of microalgae. Ethanol production from sugarcane, for instance, generates significant amounts of organically rich effluent, the vinasse. After anaerobic digestion treatment, nutrient remaining in such an effluent can be used to grow microalgae. This research aimed to testing the potential of the anaerobic treated vinasse as an alternative source of nutrients for culturing microalgae with the goal of supplying the biodiesel industrial chain with algal biomass and oil. The anaerobic process treating vinasse reached a steady state at about 17 batch cycles of 24 h producing about 0.116 m(3)CH4 kgCODvinasse (-1). The highest productivity of Chlorella vulgaris biomass (70 mg l(-1) day(-1)) was observed when using medium prepared with the anaerobic digester effluent. Lipid productivity varied from 0.5 to 17 mg l(-1) day(-1). Thus, the results show that it is possible to integrate the culturing of microalgae with the sugarcane industry by means of anaerobic digestion of the vinasse. There is also the advantageous possibility of using by-products of the anaerobic digestion such as methane and CO2 for sustaining the system with energy and carbon source, respectively. PMID:24013860

  7. Navigating wastewater energy recovery strategies: a life cycle comparison of anaerobic membrane bioreactor and conventional treatment systems with anaerobic digestion.

    PubMed

    Smith, Adam L; Stadler, Lauren B; Cao, Ling; Love, Nancy G; Raskin, Lutgarde; Skerlos, Steven J

    2014-05-20

    The objective of this study was to evaluate emerging anaerobic membrane bioreactor (AnMBR) technology in comparison with conventional wastewater energy recovery technologies. Wastewater treatment process modeling and systems analyses were combined to evaluate the conditions under which AnMBR may produce more net energy and have lower life cycle environmental emissions than high rate activated sludge with anaerobic digestion (HRAS+AD), conventional activated sludge with anaerobic digestion (CAS+AD), and an aerobic membrane bioreactor with anaerobic digestion (AeMBR+AD). For medium strength domestic wastewater treatment under baseline assumptions at 15 °C, AnMBR recovered 49% more energy as biogas than HRAS+AD, the most energy positive conventional technology considered, but had significantly higher energy demands and environmental emissions. Global warming impacts associated with AnMBR were largely due to emissions of effluent dissolved methane. For high strength domestic wastewater treatment, AnMBR recovered 15% more net energy than HRAS+AD, and the environmental emissions gap between the two systems was reduced. Future developments of AnMBR technology in low energy fouling control, increased flux, and management of effluent methane emissions would make AnMBR competitive with HRAS+AD. Rapid advancements in AnMBR technology must continue to achieve its full economic and environmental potential as an energy recovery strategy for domestic wastewater. PMID:24742289

  8. Feasibility assessment tool for urban anaerobic digestion in developing countries.

    PubMed

    Lohri, Christian Riuji; Rodi?, Ljiljana; Zurbrügg, Christian

    2013-09-15

    This paper describes a method developed to support feasibility assessments of urban anaerobic digestion (AD). The method not only uses technical assessment criteria but takes a broader sustainability perspective and integrates technical-operational, environmental, financial-economic, socio-cultural, institutional, policy and legal criteria into the assessment tool developed. Use of the tool can support decision-makers with selecting the most suitable set-up for the given context. The tool consists of a comprehensive set of questions, structured along four distinct yet interrelated dimensions of sustainability factors, which all influence the success of any urban AD project. Each dimension answers a specific question: I) WHY? What are the driving forces and motivations behind the initiation of the AD project? II) WHO? Who are the stakeholders and what are their roles, power, interests and means of intervention? III) WHAT? What are the physical components of the proposed AD chain and the respective mass and resource flows? IV) HOW? What are the key features of the enabling or disabling environment (sustainability aspects) affecting the proposed AD system? Disruptive conditions within these four dimensions are detected. Multi Criteria Decision Analysis is used to guide the process of translating the answers from six sustainability categories into scores, combining them with the relative importance (weights) attributed by the stakeholders. Risk assessment further evaluates the probability that certain aspects develop differently than originally planned and assesses the data reliability (uncertainty factors). The use of the tool is demonstrated with its application in a case study for Bahir Dar in Ethiopia. PMID:23722149

  9. Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature.

    PubMed

    Shao, Liming; Wang, Tianfeng; Li, Tianshui; Lü, Fan; He, Pinjing

    2013-07-01

    Aerobic and anaerobic digestion are popular methods for the treatment of waste activated sludge. However, the differences in degradation of sludge during aerobic and anaerobic digestion remain unclear. In this study, the sludge degradation during aerobic and anaerobic digestion was investigated at mesophilic temperature, focused on protein based on the degradation efficiency and degree of humification. The duration of aerobic and anaerobic digestion was about 90 days. The final degradation efficiency of volatile solid was 66.1 ± 1.6% and 66.4 ± 2.4% under aerobic and anaerobic conditions, respectively. The final degradation efficiency of protein was 67.5 ± 1.4% and 65.1 ± 2.6% under aerobic and anaerobic conditions, respectively. The degradation models of volatile solids were consistent with those of protein under both aerobic and anaerobic conditions. The solubility of protein under aerobic digestion was greater than that under anaerobic digestion. Moreover, the humification index of dissolved organic matter of aerobic digestion was greater than that during anaerobic digestion. PMID:23685650

  10. [Enhancement for anaerobic digestion of sewage sludge pretreated by microwave and its combined processes ].

    PubMed

    Liu, Ji-bao; Ni, Xiao-tang; Wei, Yuan-song; Tong, Juan; Wang, Ya-wei

    2014-09-01

    To improve anaerobic digestion and dewatering of sludge, impacts of sludge pretreated by microwave (MW) and its combined processes on sludge anaerobic digestion and dewatering were investigated. The results showed that microwave and its combined processes could effectively enhance anaerobic sludge digestion. Not only the cumulative methane production in the test of the MW-H2O2-alkaline (0. 2) was increased by 13. 34% compared with the control, but also its methane production rate was much higher than that of the control. Compared with the single MW process, the addition of both H2O2 and alkaline enhanced the solubilization of particle COD( >0. 45 micron) , indicating that synergistically generated soluble organics were faster to biodegrade which resulted in the enhancement of anaerobic digestion. The MW-acid process was effective in improving sludge dewaterability, e. g. , Capillary Suction Time (CST) at only 9. 85 s. The improvement of sludge dewatering was significantly correlated with sludge physical properties such as zeta potential, surface charge density and particle size. Under different sludge pretreatment conditions, the sludge dewatering after anaerobic digestion was similar, though the difference of sludge dewatering to some degrees was observed for pretreated sludge. PMID:25518665

  11. Long-term anaerobic digestion of food waste stabilized by trace elements

    SciTech Connect

    Zhang Lei, E-mail: wxzyfx@yahoo.com [Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Linggong Road 2, Dalian 116024 (China); Jahng, Deokjin, E-mail: djahng@mju.ac.kr [Department of Environmental Engineering and Biotechnology, Myongji University, San 38-2, Namdong, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728 (Korea, Republic of)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Korean food waste was found to contain low level of trace elements. Black-Right-Pointing-Pointer Stable anaerobic digestion of food waste was achieved by adding trace elements. Black-Right-Pointing-Pointer Iron played an important role in anaerobic digestion of food waste. Black-Right-Pointing-Pointer Cobalt addition further enhanced the process performance in the presence of iron. - Abstract: The purpose of this study was to examine if long-term anaerobic digestion of food waste in a semi-continuous single-stage reactor could be stabilized by supplementing trace elements. Contrary to the failure of anaerobic digestion of food waste alone, stable anaerobic digestion of food waste was achieved for 368 days by supplementing trace elements. Under the conditions of OLR (organic loading rates) of 2.19-6.64 g VS (volatile solid)/L day and 20-30 days of HRT (hydraulic retention time), a high methane yield (352-450 mL CH{sub 4}/g VS{sub added}) was obtained, and no significant accumulation of volatile fatty acids was observed. The subsequent investigation on effects of individual trace elements (Co, Fe, Mo and Ni) showed that iron was essential for maintaining stable methane production. These results proved that the food waste used in this study was deficient in trace elements.

  12. Anaerobic co-digestion of the marine microalga Nannochloropsis salina with energy crops.

    PubMed

    Schwede, Sebastian; Kowalczyk, Alexandra; Gerber, Mandy; Span, Roland

    2013-11-01

    Anaerobic co-digestion of corn silage with the marine microalga Nannochloropsis salina was investigated under batch and semi-continuous conditions. Under batch conditions process stability and biogas yields significantly increased by microalgae addition. During semi-continuous long-term experiments anaerobic digestion was stable in corn silage mono- and co-digestion with the algal biomass for more than 200 days. At higher organic loading rates (4.7 kg volatile solids m(-3)d(-1)) inhibition and finally process failure occurred in corn silage mono-digestion, whereas acid and methane formation remained balanced in co-digestion. The positive influences in co-digestion can be attributed to an adjusted carbon to nitrogen ratio, enhanced alkalinity, essential trace elements and a balanced nutrient composition. The results suggest that N. salina biomass is a suitable feedstock for anaerobic co-digestion of energy crops, especially for regions with manure scarcity. Enhanced process stability may result in higher organic loading rates or lower digester volumes. PMID:24071442

  13. Environmental implications of anaerobic digestion for manure management in dairy farms in Mexico: a life cycle perspective.

    PubMed

    Rivas-García, Pasiano; Botello-Álvarez, José E; Abel Seabra, Joaquim E; da Silva Walter, Arnaldo C; Estrada-Baltazar, Alejandro

    2015-09-01

    The environmental profile of milk production in Mexico was analysed for three manure management scenarios: fertilization (F), anaerobic digestion (AD) and enhanced anaerobic digestion (EAD). The study used the life cycle assessment (LCA) technique, considering a 'cradle-to-gate' approach. The assessment model was constructed using SimaPro LCA software, and the life cycle impact assessment was performed according to the ReCiPe method. Dairy farms with AD and EAD scenarios were found to exhibit, respectively, 12% and 27% less greenhouse gas emissions, 58% and 31% less terrestrial acidification, and 3% and 18% less freshwater eutrophication than the F scenario. A different trend was observed in the damage to resource availability indicator, as the F scenario presented 6% and 22% less damage than the EAD and AD scenarios, respectively. The magnitude of environmental damage from milk production in the three dairy manure management scenarios, using a general single score indicator, was 0.118, 0.107 and 0.081?Pt/L of milk for the F, AD and EAD scenarios, respectively. These results indicate that manure management systems with anaerobic digestion can improve the environmental profile of each litre of milk produced. PMID:25732709

  14. Two-stage anaerobic digestion of energy crops: methane production, nitrogen mineralisation and heavy metal mobilisation.

    PubMed

    Lehtomäki, A; Björnsson, L

    2006-02-01

    Energy crops (willow, sugar beet and grass silage) were digested in pilot scale two-stage anaerobic digesters. The specific methane yields obtained were 0.16, 0.38 and 0.39 m3 kg(-1) added volatile solids (VSadded) for willow, sugar beet and grass, respectively, corresponding to yearly gross energy yields of 15, 53 and 26 megawatt-hours (MWh) per hectare. With grass and sugar beets as substrate, 84-85% of the harvestable methane was obtained within 30 days. In pilot scale two-stage digestion of willow and sugar beet, 56 and 85% of the laboratory scale methane yields were obtained, but digestion of grass in two-stage reactors yielded 5% more methane than digestion in laboratory scale completely mixed low solids systems, possibly due to the pH conditions favourable to hydrolysis in the two-stage system. In digestion of grass and sugar beet the liquid at the end of digestion was rich in ammonium nitrogen, and the nitrogen in the substrate was efficiently mineralised. The results show that heavy metal concentrations are not likely to limit the utilisation of residues from digestion of nonmetal accumulating crops. Efficient mobilisation of heavy metals during the acidic phase of digestion revealed the possibility of removing metals from leachate generated in two-stage anaerobic digestion of phytoextracting crops. PMID:16506517

  15. Terminal reactions in the anaerobic digestion of animal waste.

    PubMed

    Boone, D R

    1982-01-01

    An anaerobic mesophilic digestor was operated using beef cattle waste (diluted to 5.75% volatile solids) as substrate; retention time was 10 days with daily batch feed. Volatile solids destruction was 36%. Daily gas production rate was 1.8 liters of gas (standard temperature and pressure) per liter of digestor contents (0.99 liters of CH(4) per liter of digestor contents). Acetate turnover was measured, and it was calculated that 68% of the CH(4) was derived from the methyl group of acetate. When the methanogenic substrates acetic acid or H(2)/CO(2) were added to the digestor on a continuous basis, the microflora were able to adapt and convert them to terminal products while continuing to degrade animal waste to the same extent as without additions. The methanogenic substrates were added at a rate at least 1.5 times the microbial production rate which was measured in the absence of added substrates. Added acetate was converted directly to CH(4) by acetoclastic methanogens; H(2) addition greatly stimulated acetate production in the digestor. A method is described for the measurement of acetate turnover in batch-fed digestors. PMID:16345928

  16. Terminal reactions in the anaerobic digestion of animal waste

    SciTech Connect

    Boone, D.R.

    1982-01-01

    An anaerobic mesophilic digestor was operated using beef cattle waste (diluted to 5.75% volatile solids) as substrate; retention time was 10 days with daily batch feed. Volatile solids destruction was 36%. Daily gas production rate was 1.8 liters of gas (standard temperature and pressure) per liter of digestor contents (0.99 liters of CH/sub 4/ per liter of digestor contents). Acetate turnover was measured, and it was calculated that 68% of the CH/sub 4/ was derived from the methyl group of acetate. When the methanogenic substrates acetic acid or H/sub 2//CO/sub 2/ were added to the digestor on a continuous basis, the microflora were able to adapt and convert them to terminal products while continuing to degrade animal waste to the same extent as without additions. The methanogenic substrates were added at a rate at least 1.5 times the microbial production rate which was measured in the absence of added substrates. Added acetate was converted directly to CH/sub 4/ by acetoclastic methanogens; H/sub 2/ addition greatly stimulated acetate production in the digestor. A method is described for the measurement of acetate turnover in bacth-fed digestors.

  17. Mixed culture model of anaerobic digestion: application to the evaluation of startup procedures

    SciTech Connect

    Dalla Torre, A.; Stephanopoulos, G.

    1986-07-01

    The successful operation of anaerobic digestion depends on the balanced growth of many bacterial species. The functions of the main groups of microorganisms present in a digester have been analyzed and a mathematical model constructed that describes the interactions among the microbial populations and their effect on the digester performance. The model was validated by comparing its predictions with actual digester operation. Several start-up procedures were evaluated in the light of the model predictions and improvements on current operational practices suggested in order to minimize startup time. 29 references.

  18. MICROBIAL DESTRUCTIONS ACHIEVED BY FULL-SCALE ANAEROBIC DIGESTION

    EPA Science Inventory

    As part of studies undertaken to investigate the pathogen reducing capabilities of conventional sludge stabilization procedures, microbial reductions produced by mesophilic and thermophilic digestion at the Los Angeles Hyperion Plant were examined. Samples from the digester feed ...

  19. Rapid start-up of thermophilic anaerobic digestion with the turf fraction of MSW as inoculum.

    PubMed

    Suwannoppadol, Suwat; Ho, Goen; Cord-Ruwisch, Ralf

    2011-09-01

    This study aims to determine suitable start-up conditions and inoculum sources for thermophilic anaerobic digestion. Within days of incubation MSW at 55°C, methane was produced at a high rate. In an attempt to narrow down which components of typical MSW contained the thermophilic methanogens, vacuum cleaner dust, banana peel, kitchen waste, and garden waste were tested as inoculum for thermophilic methanogenesis with acetate as the substrate. Results singled out grass turf as the key source of thermophilic acetate degrading methanogenic consortia. Within 4 days of anaerobic incubation (55°C), anaerobically incubated grass turf samples produced methane accompanied by acetate degradation enabling successful start-up of thermophilic anaerobic digestion. Other essential start-up conditions are specified. Stirring of the culture was not conducive for successful start-up as it resulted specifically in propionate accumulation. PMID:21723117

  20. High frequency ultrasound pretreatment for sludge anaerobic digestion: effect on floc structure and microbial population.

    PubMed

    Braguglia, C M; Gagliano, M C; Rossetti, S

    2012-04-01

    In this work the potential of high frequency ultrasounds as pretreatment for sludge anaerobic digestion has been assessed. Irradiation with 200kHz ultrasounds was efficient in disintegrating the floc structure increasing the available fraction of soluble organic matter (up to seven times at 25,000kJ/kgTS). Batch anaerobic digestion tests were carried out on lab-scale reactors fed either with untreated or disintegrated sludge inoculated with anaerobic sludge, at different feed/inoculum ratio (F/I=0.5 and 1). Degradation of particulate matter, biogas production and related microbial community composition (estimated by fluorescence in situ hybridization, FISH) were investigated. Sludge ultrasounds pretreatment led to an overall improvement of the digestion performances, with a maximum biogas gain of 40% at F/I=0.5. FISH showed a key-role of Methanosarcina spp. in the main reactions of biogas synthesis. PMID:22326112

  1. Enhanced stabilization of digested sludge during long-term storage in anaerobic lagoons.

    PubMed

    Lukicheva, Irina; Pagilla, Krishna; Tian, Guanglong; Cox, Albert; Granato, Thomas

    2014-04-01

    The goal of this work was to study changes in anaerobically stored digested sludge under different lengths of storage time to evaluate the quality of final product biosolids. The analyses of collected data suggest the organic matter degradation occurrence in the anaerobic environment of the lagoon approximately within the first year. After that, the degradation becomes very slow, which is likely caused by unfavorable environmental conditions. The performance of lagoon aging of digested sludge was also compared to the performance of lagoon aging of anaerobically digested and dewatered sludge. It was concluded that both of these processes result in biosolids of comparative quality and that the former provides more economical solution to biosolids handling by eliminating the need for mechanical dewatering. PMID:24851324

  2. Bioavailability of Cu and Zn in raw and anaerobically digested pig slurry.

    PubMed

    Marcato, Claire-Emmanuelle; Pinelli, Eric; Cecchi, Marie; Winterton, Peter; Guiresse, Maritxu

    2009-07-01

    The impact of anaerobic digestion on the bioavailability of copper and zinc from pig slurry was assessed. Both chemical and biological approaches were used independently on raw slurry (RS) and anaerobically digested pig slurry (DS). This work, using ultracentrifugation pellets from the same pig slurry before and after an anaerobic treatment, confirmed that Cu and Zn behave differently in terms of bioavailability, and contrasting results were obtained by chemical and biological assessments. A chemical approach combined a preliminary study of the pH effect on particulate/dissolved metal partitioning, sequential extraction, and biochemical fractionation. This approach tended to show a lower mobility of metals from digested slurry (DS). A biological approach was carried out with Zea mays and Vicia faba to study Cu and Zn uptake in soil amended with RS or DS. This assay could not differentiate the two slurries. PMID:19200597

  3. Evaluating a model of anaerobic digestion of organic wastes through system identification

    SciTech Connect

    Anex, R.P.; Kiely, G.

    1999-07-01

    Anaerobic digestion of the organic fraction of municipal solid waste (MSW), on its own or co-digested with primary sewage sludge (PSS), produces high quality biogas, suitable as renewable energy. Parameter estimation and evaluation of a two-stage mathematical model of the anaerobic co-digestion of the organic fraction of MSW and PSS are described. Measured data are from a bench scale laboratory experiment using a continuously stirred tank reactor and operated at 36 C for 115 days. The two-stage model simulates acidogenesis and methanogenesis, including ammonia inhibition. Model parameters are estimated using an output error, Levenberg-Marquardt (LM) algorithm. Sensitivity of the estimated parameter values and the model outputs to non-estimated model parameters and measurement errors are evaluated. The estimated mathematical model successfully predicts the performance of the anaerobic reactor. Sensitivity results provide guidance for improving the model structure and experimental procedures.

  4. Modular Expert System for the Diagnosis of Operating Conditions of Industrial Anaerobic Digestion Plants (TELEMAC Contribution #5)

    Microsoft Academic Search

    L. Lardon; A. Puñal; J. P. Steyer; J. A. Martinez

    Anaerobic digestion (AD) plants are highly efficient wastewater treatment processes with possible energetic valorisation. Despite these advantages, many industries are still reluctant to use them because of their instability in front of changes in operating conditions. To face this major drawback and to enhance the industrial use of anaerobic digestion, one solution is to develop and to implement knowledge base

  5. AN INNOVATIVE DESIGN FOR ANAEROBIC CO-DIGESTION OF ANIMAL WASTES FOR SUSTAINABLE DEVELOPMENT IN RURAL COMMUNITIES

    EPA Science Inventory

    With the aim of the Phase I project to develop an innovative anaerobic co-digestion design for the treatment of dairy manure and poultry waste, our Phase I team has evaluated the technical and economic feasibility of the anaerobic co-digestion design concept with a thorough in...

  6. Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters

    Microsoft Academic Search

    K. Kujawa-Roeleveld; T. A. Elmitwalli; G. Zeeman

    2006-01-01

    Anaerobic digestion of concentrated domestic wastewater streams - black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR - decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations

  7. Biochemical methane potential and solid state anaerobic digestion of Korean food wastes

    Microsoft Academic Search

    Ho Nam Chang; Soon Chul Park

    1995-01-01

    In order to develop an anaerobic digestion process for Korean food wastes containing 15–30% total solids (TS) the biochemical methane potentials (BMP) of their components and mixture (mixed food waste, MFW) were measured. The methane yields of cooked meat, cellulose (as control), boiled rice, fresh cabbage and MFW were 482, 356, 294, 277 and 472 ml CH4\\/gVS added and anaerobic

  8. Two-phases anaerobic digestion of fruit and vegetable wastes: bioreactors performance

    Microsoft Academic Search

    H. Bouallagui; M. Torrijos; J. J. Godon; R. Moletta; R. Ben Cheikh; Y. Touhami; J. P. Delgenes; M. Hamdi

    2004-01-01

    The two-phase anaerobic digestion of a mixture of fruit and vegetable wastes (FVW) was studied, using two coupled anaerobic sequencing batch reactors (ASBR) operated at mesophilic temperature. The effect of increasing loading rates on the acidification step was investigated. Results indicated that the hydrolysis yield (81%) stabilized at an OLR of 7.5g COD\\/L.d. The volatile fatty acids concentration increased when

  9. Methanogenic population dynamics during start-up of anaerobic digesters treating municipal solid waste and biosolids

    Microsoft Academic Search

    Matt E. Griffin; Katherine D. McMahon; Roderick I. Mackie; Lutgarde Raskin

    1998-01-01

    An aggressive start-up strategy was used to initiate codigestion in two anaerobic, continuously mixed bench-top reactors at mesophilic (37°C) and ther- mophilic (55°C) conditions. The digesters were inocu- lated with mesophilic anaerobic sewage sludge and cattle manure and were fed a mixture of simulated mu- nicipal solid waste and biosolids in proportions that re- flect U.S. production rates. The design

  10. Enhancing anaerobic digestibility and phosphorus recovery of dairy manure through microwave-based thermochemical pretreatment.

    PubMed

    Jin, Ying; Hu, Zhenhu; Wen, Zhiyou

    2009-08-01

    Anaerobic digestion and struvite precipitation are two effective ways of treating dairy manure for recovering biogas and phosphorus. Anaerobic digestion of dairy manure is commonly limited by slow fiber degradation, while struvite precipitation is limited by the availability of orthophosphate. The aim of this work is to study the possibility of using microwave-based thermochemical pretreatment to simultaneously enhance manure anaerobic digestibility (through fiber degradation) and struvite precipitation (through phosphorus solubilization). Microwave heating combined with different chemicals (NaOH, CaO, H(2)SO(4), or HCl) enhanced solubilization of manure and degradation of glucan/xylan in dairy manure. However, sulfuric acid-based pretreatment resulted in a low anaerobic digestibility, probably due to the sulfur inhibition and Maillard side reaction. The pretreatments released 20-40% soluble phosphorus and 9-14% ammonium. However, CaO-based pretreatment resulted in lower orthophosphate releases and struvite precipitation efficiency as calcium interferes with phosphate to form calcium phosphate. Collectively, microwave heating combined with NaOH or HCl led to a high anaerobic digestibility and phosphorus recovery. Using these two chemicals, the performance of microwave- and conventional-heating in thermochemical pretreatment was further compared. The microwave heating resulted in a better performance in terms of COD solubilization, glucan/xylan reduction, phosphorus solubilization and anaerobic digestibility. Lastly, temperature and heating time used in microwave treatment were optimized. The optimal values of temperature and heating time were 147 degrees C and 25.3 min for methane production, and 135 degrees C and 26 min for orthophosphate release, respectively. PMID:19555991

  11. Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production.

    PubMed

    Nges, Ivo Achu; Escobar, Federico; Fu, Xinmei; Björnsson, Lovisa

    2012-01-01

    Currently, there is increasing competition for waste as feedstock for the growing number of biogas plants. This has led to fluctuation in feedstock supply and biogas plants being operated below maximum capacity. The feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) was therefore studied in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process. Co-digesting industrial waste and crops led to significant improvement in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also avoids the need for micronutrients normally required in crop digestion. The batch co-digestion methane yields were used to predict co-digestion methane yield in full scale operation. This was done based on the ratio of methane yields observed for laboratory batch and CSTR experiments compared to full scale CSTR digestion of industrial waste. The economy of crop-based biogas production is limited under Swedish conditions; therefore, adding crops to existing industrial waste digestion could be a viable alternative to ensure a constant/reliable supply of feedstock to the anaerobic digester. PMID:21975301

  12. Should We Build “Obese” or “Lean” Anaerobic Digesters?

    PubMed Central

    Briones, Aurelio; Coats, Erik; Brinkman, Cynthia

    2014-01-01

    Conventional anaerobic digesters (ADs) treating dairy manure are fed with raw or fermented manure rich in volatile fatty acids (VFAs). In contrast, pre-fermented AD (PF-AD) is fed with the more recalcitrant, fiber-rich fraction of manure that has been pre-fermented and depleted of VFAs. Thus, the substrate of PF-AD may be likened to a lean diet rich in fibers while the pre-fermentation stage fermenter is fed a relatively rich diet containing labile organic substances. Previous results have shown that conventional and pre-fermented ADs fed with raw or pre-fermented manure, respectively, produced comparable methane yields. The primary objective of this study was to characterize, using next-generation DNA sequencing, the bacterial communities in various bioreactors (pre-fermentation stage fermenter; various operational arrangements PF-AD; conventional single-stage AD; and a full scale AD) and compare the Firmicutes to Bacteroidetes (F/B) ratios in these different systems. Firmicutes and Bacteroidetes constituted the two most abundant phyla in all AD samples analyzed, as well as most of the samples analyzed in the fermenters and manure samples. Higher relative abundance of Bacteroidetes, ranging from 26% to 51% of bacteria, tended to be associated with PF-AD samples, while the highest relative abundance of Firmicutes occurred in the fermenter (maximum of 76% of bacteria) and manure (maximum of 66% of bacteria) samples. On average, primary stage fermenters exhibited microbiological traits linked to obesity: higher F/B ratios and a ‘diet’ that is less fibrous and more labile compared to that fed to PF-AD. On the other hand, microbial characteristics associated with leanness (lower F/B ratios combined with fibrous substrate) were associated with PF-AD. We propose that bacterial communities in AD shift depending on the quality of substrate, which ultimately results in maintaining VFA yields in PF-AD, similar to the role of bacterial communities and a high fiber diet in lean mice. PMID:24831948

  13. Inoculum selection is crucial to ensure operational stability in anaerobic digestion.

    PubMed

    De Vrieze, Jo; Gildemyn, Sylvia; Vilchez-Vargas, Ramiro; Jáuregui, Ruy; Pieper, Dietmar H; Verstraete, Willy; Boon, Nico

    2015-01-01

    Anaerobic digestion is considered a key technology for the future bio-based economy. The microbial consortium carrying out the anaerobic digestion process is quite complex, and its exact role in terms of "elasticity", i.e., the ability to rapidly adapt to changing conditions, is still unknown. In this study, the role of the initial microbial community in terms of operational stability and stress tolerance was evaluated during a 175-day experiment. Five different inocula from stable industrial anaerobic digesters were fed a mixture of waste activated sludge and glycerol. Increasing ammonium pulses were applied to evaluate stability and stress tolerance. A different response in terms of start-up and ammonium tolerance was observed among the different inocula. Methanosaetaceae were the dominant acetoclastic methanogens, yet, Methanosarcinaceae increased in abundance at elevated ammonium concentrations. A shift from a Firmicutes to a Proteobacteria dominated bacterial community was observed in failing digesters. Methane production was strongly positively correlated with Methanosaetaceae, but also with Bacteria related to Anaerolinaceae, Clostridiales, and Alphaproteobacteria. Volatile fatty acids were strongly positively correlated with Betaproteobacteria and Bacteroidetes, yet ammonium concentration only with Bacteroidetes. Overall, these results indicate the importance of inoculum selection to ensure stable operation and stress tolerance in anaerobic digestion. PMID:25261127

  14. Potential for energy generation from anaerobic digestion of food waste in Australia.

    PubMed

    Lou, Xian Fang; Nair, Jaya; Ho, Goen

    2013-03-01

    Published national and state reports have revealed that Australia deposits an average of 16 million Mg of solid waste into landfills yearly, of which approximately 12.6% is comprised of food. Being highly biodegradable and possessing high energy content, anaerobic digestion offers an attractive treatment option alternative to landfilling. The present study attempted to identify the theoretical maximum benefit of food waste digestion in Australia with regard to energy recovery and waste diversion from landfills. The study also assessed the scope for anaerobic process to utilize waste for energy projects through various case study scenarios. Results indicated anaerobic digestion of total food waste generated across multiple sites in Australia could generate 558 453 dam(3) of methane which translated to 20.3 PJ of heating potential or 1915 GWe in electricity generation annually. This would contribute to 3.5% of total current energy supply from renewable sources. Energy contribution from anaerobic digestion of food waste to the total energy requirement in Australia remains low, partially due to the high energy consumption of the country. However its appropriateness in low density regions, which are prevalent in Australia, may allow digesters to have a niche application in the country. PMID:23381970

  15. Anaerobic waste-activated sludge digestion - A bioconversion mechanism and kinetic model

    SciTech Connect

    Shimizu, Tatsuo; Kudo, Kenzo; Nasu, Yoshikazu (Hokkaido Univ., Sapporo (Japan))

    1993-05-01

    The anaerobic bioconversion of raw and mechanically lysed waste-activated sludge was kinetically investigated. The hydrolysis of the biopolymers, such as protein, which leaked out from the biological sludge with ultrasonic lysis, was a first-order reaction in anaerobic digestion and the rate constant was much higher than the decay rate constant of the raw waste activated sludge. An anaerobic digestion model that is capable of evaluating the effect of the mechanical sludge lysis on digestive performance was developed. The present model includes four major biological processes - the release of intracellular matter with sludge lysis; hydrolysis of biopolymers to volatile acids; the degradation of various volatile acids to acetate; and the conversion of acetate and hydrogen to methane. Each process was assumed to follow first-order kinetics. The model approximately simulated the overall process performance of the anaerobic digestion of waste-activated sludge. The model suggested that when the lysed waste-activated sludge was fed, the overall digestive performance remarkably increased in the two-phase system consisting of an acid forming process and a methanogenic process, which ensured the symbiotic growth of acetogenic and methanogenic bacteria.

  16. CFD simulation of non-Newtonian fluid flow in anaerobic digesters.

    PubMed

    Wu, Binxin; Chen, Shulin

    2008-02-15

    A general mathematical model that predicts the flow fields in a mixed-flow anaerobic digester was developed. In this model, the liquid manure was assumed to be a non-Newtonian fluid, and the flow governed by the continuity, momentum, and k-epsilon standard turbulence equations, and non-Newtonian power law model. The commercial computational fluid dynamics (CFD) software, Fluent, was applied to simulate the flow fields of lab-scale, scale-up, and pilot-scale anaerobic digesters. The simulation results were validated against the experimental data from literature. The flow patterns were qualitatively compared for Newtonian and non-Newtonian fluids flow in a lab-scale digester. Numerical simulations were performed to predict the flow fields in scale-up and pilot-scale anaerobic digesters with different water pump power inputs and different total solid concentration (TS) in the liquid manure. The optimal power inputs were determined for the pilot-scale anaerobic digester. Some measures for reducing dead and low velocity zones were proposed based upon the CFD simulation results. PMID:17705227

  17. Biodegradation of pulp and paper mill effluent using anaerobic followed by aerobic digestion.

    PubMed

    Bishnoi, Narsi R; Khumukcham, R K; Kumar, Rajender

    2006-05-01

    An experimental study was carried to find out the degradability of black liquor of pulp and paper mill wastewater for biomethanogenesis in continuous stirred tank reactor (CSTR) and followed by activated sludge process (ASP). Continuous stirred tank reactor was used in present study for anaerobic digestion of black liquor, while completely mixed activated sludge system was used for aerobic digestion. A maximum methane production was found up to 430 ml/day, chemical oxygen demand was reduced up to 64% and total volatile fatty acid increased up to 1500 mg/l from 975 mg/l at 7.3 pH, 37 degrees C temperature and 8 days hydraulic retention time during anaerobic digestion. In activated sludge process (aerobic digestion) chemical oxygen demand and biological oxygen demand reduction were 81% and 86% respectively at 72 hr hydraulic retention time. PMID:17436533

  18. Phase distribution and removal of pharmaceuticals and personal care products during anaerobic sludge digestion.

    PubMed

    Narumiya, Masanori; Nakada, Norihide; Yamashita, Naoyuki; Tanaka, Hiroaki

    2013-09-15

    The fate and removal of 48 pharmaceuticals and personal care products (PPCPs) during anaerobic digestion of sewage sludge were investigated in four full-scale sewage treatment plants (STPs). We measured concentrations in both the liquid and solid phases of the sludge to compare the distribution ratios (Kd) between phases before and after digestion. The results showed changes in Kd values of PPCPs with carboxyl or amino functional groups, probably due to a shift of dissociation equilibrium with the increase in pH. Sulfamethoxazole and trimethoprim were almost completely degraded (>90%); triclosan, triclocarban, and ofloxacin were moderately degraded (around 30-50%); but carbamazepine was not eliminated. To our knowledge, this is the first report that shows (i) the occurrence and removal of several tens of PPCPs by anaerobic sludge digestion in full-scale municipal STPs and (ii) the change of distribution between the liquid and solid phases during digestion. PMID:23774781

  19. Contribution of anaerobic digesters to emissions mitigation and electricity generation under U.S. climate policy.

    PubMed

    Zaks, David P M; Winchester, Niven; Kucharik, Christopher J; Barford, Carol C; Paltsev, Sergey; Reilly, John M

    2011-08-15

    Livestock husbandry in the U.S. significantly contributes to many environmental problems, including the release of methane, a potent greenhouse gas (GHG). Anaerobic digesters (ADs) break down organic wastes using bacteria that produce methane, which can be collected and combusted to generate electricity. ADs also reduce odors and pathogens that are common with manure storage and the digested manure can be used as a fertilizer. There are relatively few ADs in the U.S., mainly due to their high capital costs. We use the MIT Emissions Prediction and Policy Analysis (EPPA) model to test the effects of a representative U.S. climate stabilization policy on the adoption of ADs which sell electricity and generate methane mitigation credits. Under such policy, ADs become competitive at producing electricity in 2025, when they receive methane reduction credits and electricity from fossil fuels becomes more expensive. We find that ADs have the potential to generate 5.5% of U.S. electricity. PMID:21761880

  20. Contribution of Anaerobic Digesters to Emissions Mitigation and Electricity Generation Under U.S. Climate Policy

    PubMed Central

    2011-01-01

    Livestock husbandry in the U.S. significantly contributes to many environmental problems, including the release of methane, a potent greenhouse gas (GHG). Anaerobic digesters (ADs) break down organic wastes using bacteria that produce methane, which can be collected and combusted to generate electricity. ADs also reduce odors and pathogens that are common with manure storage and the digested manure can be used as a fertilizer. There are relatively few ADs in the U.S., mainly due to their high capital costs. We use the MIT Emissions Prediction and Policy Analysis (EPPA) model to test the effects of a representative U.S. climate stabilization policy on the adoption of ADs which sell electricity and generate methane mitigation credits. Under such policy, ADs become competitive at producing electricity in 2025, when they receive methane reduction credits and electricity from fossil fuels becomes more expensive. We find that ADs have the potential to generate 5.5% of U.S. electricity. PMID:21761880

  1. Optimizing the anaerobic digestion of microalgae in a coupled process Terence Bayen1,4 and Francis Mairet2 and Pierre Martinon3 and Matthieu Sebbah4

    E-print Network

    Boyer, Edmond

    Optimizing the anaerobic digestion of microalgae in a coupled process Terence Bayen1,4 and Francis the production of methane in a bioreactor coupling an anaerobic digester and a culture of micro-algae limited as an attractive alternative for sustainable energy production [2]. Anaerobic digestion can be applied to convert

  2. Comparison of different liquid anaerobic digestion effluents as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover

    SciTech Connect

    Xu Fuqing; Shi Jian [Department of Food, Agricultural and Biological Engineering, Ohio State University, Ohio Agricultural Research and Development Center, 1680 Madison Ave., Wooster, OH 44691 (United States); Lv Wen; Yu Zhongtang [Department of Animal Sciences, Ohio State University, Columbus, OH 43210 (United States); Li Yebo, E-mail: li.851@osu.edu [Department of Food, Agricultural and Biological Engineering, Ohio State University, Ohio Agricultural Research and Development Center, 1680 Madison Ave., Wooster, OH 44691 (United States)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Compared methane production of solid AD inoculated with different effluents. Black-Right-Pointing-Pointer Food waste effluent (FWE) had the largest population of acetoclastic methanogens. Black-Right-Pointing-Pointer Solid AD inoculated with FWE produced the highest methane yield at F/E ratio of 4. Black-Right-Pointing-Pointer Dairy waste effluent (DWE) was rich of cellulolytic and xylanolytic bacteria. Black-Right-Pointing-Pointer Solid AD inoculated with DWE produced the highest methane yield at F/E ratio of 2. - Abstract: Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of 2, the reactor inoculated by dairy waste effluent achieved the highest methane yield of 238.5 L/kgVS{sub feed}, while at an F/E ratio of 4, the reactor inoculated by food waste effluent achieved the highest methane yield of 199.6 L/kgVS{sub feed}. The microbial population and chemical composition of the three effluents were substantially different. Food waste effluent had the largest population of acetoclastic methanogens, while dairy waste effluent had the largest populations of cellulolytic and xylanolytic bacteria. Dairy waste also had the highest C/N ratio of 8.5 and the highest alkalinity of 19.3 g CaCO{sub 3}/kg. The performance of solid-state batch anaerobic digestion reactors was closely related to the microbial status in the liquid anaerobic digestion effluents.

  3. Removal and recovery of nutrients as struvite from anaerobic digestion residues of poultry manure

    Microsoft Academic Search

    Y. D. Yilmazel; G. N. Demirer

    2011-01-01

    The removal and the recovery of nutrients, namely nitrogen (N) and phosphorus (P) from anaerobically digested and solid–liquid separated manure effluents via struvite precipitation were investigated. Both the liquid and the solid phases of the poultry manure digester effluent were subjected to struvite precipitation experiments. The Mg:N:P molar ratio of 1:1:1 in the liquid phase resulted in an average NH4?N

  4. Performance evaluation of an anaerobic hybrid digester treating palm oil mill effluent

    Microsoft Academic Search

    R. Borja; C. J. Banks; B. Khalfaoui; A. Martín

    1996-01-01

    A high?strength palm oil mill effluent was treated using a hybrid anaerobic digester, in which the bottom two?thirds were occupied by a sludge blanket and the upper one?third by submerged PVC rings, under mesophilic conditions. The influent COD concentration varied considerably (11.6–65.0 g\\/1). The digester was subjected to quantitative increases in organic loading rate (OLR) from 3.3 to 18.6 kg

  5. Evaluation of continuous mesophilic anaerobic sludge digestion after high temperature microwave pretreatment

    Microsoft Academic Search

    Isil Toreci; Kevin J. Kennedy; Ronald L. Droste

    2009-01-01

    Effect of microwave pretreatment (MW) high temperature (175°C) and MW intensity to waste activated sludge digested with acclimatized inoculum in single- and dual-stage semi-continuous mesophilic anaerobic digesters at different sludge retention times (SRTs) (20, 10 and 5 days) were investigated. MW pretreatment led to similar sludge stabilization at low SRTs (5 and 10 days). Although lowering MW intensity slightly improved

  6. Effect of acid speciation on solid waste liquefaction in an anaerobic acid digester

    Microsoft Academic Search

    Sandhya Babel; Kensuke Fukushi; Bunpot Sitanrassamee

    2004-01-01

    Laboratory scale experiments were carried out to evaluate and determine the suitable working conditions for the enhancement of volatile fatty acids (VFAs) production with the stabilization of solid pineapple waste (peel) simultaneously when operating two-phase anaerobic digestion. It was found that acid production, enhanced when the digester was operated at neutral pH. VFAs, could be obtained at about 50g\\/kg-waste within

  7. Two-phase continuous anaerobic digestion of fruit and vegetable wastes

    Microsoft Academic Search

    A. Mtz.-Viturtia; J. Mata-Alvarez; F. Cecchi

    1995-01-01

    Results of a two-phase mesophilic (35°C) anaerobic digestion treatment of fruit and vegetable wastes, carried out at laboratory scale, are presented and discussed. They are contrasted with other results obtained with a similar waste, but digested in a one-phase system. The yields are lower in this simple two-phase system, because of the higher organic loading rate. It is concluded that

  8. Biochar derived from anaerobically digested sugar beet tailings: Characterization and phosphate removal potential

    Microsoft Academic Search

    Ying Yao; Bin Gao; Mandu Inyang; Andrew R. Zimmerman; Xinde Cao; Pratap Pullammanappallil; Liuyan Yang

    2011-01-01

    Two biochars were produced from anaerobically digested and undigested sugar beet tailings through slow-pyrolysis at 600°C. The digested sugar beet tailing biochar (DSTC) and raw sugar beet tailing biochar (STC) yields were around 45.5% and 36.3% of initial dry weight, respectively. Compared to STC, DSTC had similar pH and surface functional groups, but higher surface area, and its surface was

  9. Monitoring methanogenic population dynamics in a full-scale anaerobic digester to facilitate operational management.

    PubMed

    Williams, Julie; Williams, Haydn; Dinsdale, Richard; Guwy, Alan; Esteves, Sandra

    2013-07-01

    Microbial populations in a full-scale anaerobic digester fed on food waste were monitored over an 18-month period using qPCR. The digester exhibited a highly dynamic environment in which methanogenic populations changed constantly in response to availability of substrates and inhibitors. The methanogenic population in the digester was dominated by Methanosaetaceae, suggesting that aceticlastic methanogenesis was the main route for the production of methane. Sudden losses (69%) in Methanosaetaceae were followed by a build-up of VFAs which were subsequently consumed when populations recovered. A build up of ammonium inhibited Methanosaetaceae and resulted in shifts from acetate to hydrogen utilization. Addition of trace elements and alkalinity when propionate levels were high stimulated microbial growth. Routine monitoring of microbial populations and VFAs provided valuable insights into the complex processes occurring within the digester and could be used to predict digester stability and facilitate digester optimization. PMID:23707910

  10. Anaerobic co-digestion of dairy manure with mulched switchgrass for improvement of the methane yield.

    PubMed

    Frigon, Jean-Claude; Roy, Caroline; Guiot, Serge R

    2012-03-01

    The owners of farm-scale anaerobic digesters are relying on off-farm wastes or energy crops as a co-digestion feedstock with animal manure in order to increase their production of methane and thus revenues. Switchgrass represents an interesting feedstock for Canadian digesters owners as it is a high-yielding low-maintenance perennial crop, well adapted to northern climate. Methane potential assays in batch tests showed methane production of 19.4 ± 3.6, 28.3 ± 1.7, 37.3 ± 7.1 and 45.7 ± 0.8 L kg(-1), for raw manure, blended manure, manure and mulched switchgrass, manure and pretreated switchgrass, respectively. Two 6-L lab-scale anaerobic digesters were operated for 130 days in order to assess the benefit of co-digesting switchgrass with bovine manure (digester #2), at a 20% wet mass fraction, compared with a manure-only operation (digester #1) The digesters were operated at an hydraulic retention time of 37 ± 6 days and at loads of 2.4 ± 0.6 and 2.6 ± 0.6 kg total volatile solids (TVS) L(-1) day(-1) for digesters #1 (D1) and #2 (D2), respectively. The TVS degradation reached 25 and 39%, which resulted in a methane production of 1.18 ± 0.18 and 2.19 ± 0.31 L day(-1) for D1 and D2, respectively. The addition of 20% on a wet mass ratio of switchgrass to a manure digester increased its methane production by 86%. The co-digestion of switchgrass in a 500 m(3) manure digester could yield up to 10.2 GJ day(-1) of purified methane or 1.1 MWh day(-1) of electricity. PMID:21779889

  11. Semi-continuous anaerobic digestion of solid poultry slaughterhouse waste: effect of hydraulic retention time and loading

    Microsoft Academic Search

    Esa A Salminen; Jukka A Rintala

    2002-01-01

    We studied the effect of hydraulic retention time (HRT) and loading on anaerobic digestion of poultry slaughterhouse wastes, using semi-continuously fed, laboratory-scale digesters at 31°C. The effect on process performance was highly significant: Anaerobic digestion appeared feasible with a loading of up to 0.8kg volatile solids (VS)\\/m3d and an HRT of 50–100 days. The specific methane yield was high, from

  12. Effective reduction of enteric bacteria and viruses during the anaerobic digestion of biomass and wastes

    SciTech Connect

    Fannin, K.F.; Hsu, P.H.; Mensinger, J.; Cahill, C.

    1984-01-01

    Natural resource depletion increases the amount of waste requiring efficient and affordable disposal alternatives. Through effective management, many of these so-called wastes can be utilized as important energy and agricultural resources. One such management approach involves the utilization of emergent aquatic plant species, such as water hyacinth, to remove nutrients from the wastewater during growth. This process produces an energy-containing biomass that can then be anaerobically digested either separately or with other waste components to produce energy-containing methane and an effluent residue containing significant quantities of protein and nutrients. This residue can be utilized as an effective fertilizer, soil conditioner, or animal feed supplement provided it is rendered reasonably safe from such contaminants as enteric microorganisms. This study was conducted to identify the digester operating parameters that affect the survival of enteric bacteria and viruses during the anaerobic digestion of blends of water hyacinth and primary sewage sludge. Solids retetion time and temperature were demonstrated to be important parameters affecting the survival of poliovirus, f-2 coliphage, Streptoccus fecalis, and Escherichia coli during anaerobic digestion. The die-off rates of the coliphages were similar to those of the poliovirus at 35/sup 0/C. S. fecalis appeared to be the most stable of any of the bacteria and viruses studied. All organisms were more stable at 25 than at 35/sup 0/C. The data demonstrate that the concentration of enteric bacteria and viruses can be effectively reduced during anaerobic digestion using techniques, such as increased solids retention times and mesophilic temperatures, that are consistent with achieving high methane yields. The survival of enteric viruses during anaerobic digestion may be affected by the characteristics of the feedstock as well as by the process operating conditions.

  13. The Effect of Ultrasonic Irradiation on the Anaerobic Digestion of Activated Sludge

    Microsoft Academic Search

    Rubina Farooq; Faiza Rehman; Sofia Baig; Maria Sadique; Sajjad Khan; Umar Farooq; Abdur Rehman; Ather Farooq; Arshed Pervez; S. F. Shaukat

    The activated sludge method is under continuous development and improvements. The slow degradation rate of sludge in anaerobic digester is due to the rate limiting step of sludge hydrolysis. This is caused by a low biodegradability of the cell walls and extra cellular biopolymers in sludge. It is important to reduce the amount of sludge produced and to reduce its

  14. Rapid start-up of thermophilic anaerobic digestion with the turf fraction of MSW as inoculum

    Microsoft Academic Search

    Suwat Suwannoppadol; Goen Ho; Ralf Cord-Ruwisch

    2011-01-01

    This study aims to determine suitable start-up conditions and inoculum sources for thermophilic anaerobic digestion. Within days of incubation MSW at 55°C, methane was produced at a high rate. In an attempt to narrow down which components of typical MSW contained the thermophilic methanogens, vacuum cleaner dust, banana peel, kitchen waste, and garden waste were tested as inoculum for thermophilic

  15. Thermophilic anaerobic digestion of Lurgi coal gasification wastewater in a UASB reactor.

    PubMed

    Wang, Wei; Ma, Wencheng; Han, Hongjun; Li, Huiqiang; Yuan, Min

    2011-02-01

    Lurgi coal gasification wastewater (LCGW) is a refractory wastewater, whose anaerobic treatment has been a severe problem due to its toxicity and poor biodegradability. Using a mesophilic (35±2°C) reactor as a control, thermophilic anaerobic digestion (55±2°C) of LCGW was investigated in a UASB reactor. After 120 days of operation, the removal of COD and total phenols by the thermophilic reactor could reach 50-55% and 50-60% respectively, at an organic loading rate of 2.5 kg COD/(m(3) d) and HRT of 24 h; the corresponding efficiencies were both only 20-30% in the mesophilic reactor. After thermophilic digestion, the wastewater concentrations of the aerobic effluent COD could reach below 200 mg/L compared with around 294 mg/L if mesophilic digestion was done and around 375 mg/L if sole aerobic pretreatment was done. The results suggested that thermophilic anaerobic digestion improved significantly both anaerobic and aerobic biodegradation of LCGW. PMID:21112778

  16. Anaerobic Digestion for Reduction and Stabilization of Organic Solid Waste During Space Missions: Systems Analysis

    Microsoft Academic Search

    Qiyong Xu; Tim Townsend; David Chynoweth; Patrick Haley; John Owens; Elana Rich; Sabrina Maxwell; Hong-Lim Choi

    High Solids Leachbed Anaerobic Digestion (HSLAD) is a biological waste treatment system that has been successfully demonstrated for solid waste treatment in terrestrial applications. The process involves a solid phase leachbed fermentation, employing leachate recycle between new and mature reactors for inoculation, wetting, and removal of volatile organic acids during startup. HSLAD also offers a potential option for treatment of

  17. Biological pretreatment enhances biogas production in the anaerobic digestion of pulp and paper sludge.

    PubMed

    Lin Yunqin; Wang Dehan; Wang Lishang

    2010-09-01

    High efficient resource recovery from pulp and paper sludge (PPS) has been the focus of attention. The objective of this research was to develop a bio-pretreatment process prior to anaerobic digestion of PPS to improve the methane productivity. Active and inactive mushroom compost extracts (MCE) were used for pretreating PPS, followed by anaerobic digestion with monosodium glutamate waste liquor (MGWL). Laboratory-scale experiments were carried out in completely mixed bioreactors, 1-L capacity with 700 ml useful capacity. Optimal amount of active MCE for organics' solubilization in the step of pretreatment was 250 A.U./gVS( sludge). Under this condition, the PPS floc structure was well disrupted, resulting in void rate and fibre size diminishment after pretreatment. In addition, SCOD and VS removal were found to be 56% and 43.6%, respectively, after anaerobic digestion, being the peak value of VFA concentration determined as 1198 mg acetic acid L(-1). The anaerobic digestion efficiency of PPS with and without pretreatment was evaluated. The highest methane yield under optimal pretreatment conditions was 0.23 m(3) CH4/kgVS(add), being 134.2% of the control. The results indicated that MCE bio-pretreatment could be a cost-effective and environmentally sound method for producing methane from PPS. PMID:20147578

  18. Anaerobic Digestion. Selected Instructional Activities and References. Instructional Resources Monograph Series.

    ERIC Educational Resources Information Center

    Townsend, Robert D., Comp.

    Focusing specifically on the wastewater treatment process of anaerobic digestion, this document identifies instructional and reference materials for use by professionals in the field in the development and implementation of new programs or in the updating of existing programs. It is designed to help trainers, plant operators, educators, engineers,…

  19. ENZYME ADDITION TO THE ANAEROBIC DIGESTION OF MUNICIPAL WASTEWATER PRIMARY SLUDGE

    EPA Science Inventory

    The study evaluates the effects of enzyme augmentation on municipal wastewater (MWW) sludge anaerobic digestion. The primary objective was to examine the impact of using enzymes to enhance the degradation of the cellulosic and the oil- and grease-rich sludge fractions. The additi...

  20. Principles and potential of the anaerobic digestion of waste-activated sludge

    Microsoft Academic Search

    Lise Appels; Jan Baeyens; Jan Degrève; Raf Dewil

    2008-01-01

    When treating municipal wastewater, the disposal of sludge is a problem of growing importance, representing up to 50% of the current operating costs of a wastewater treatment plant. Although different disposal routes are possible, anaerobic digestion plays an important role for its abilities to further transform organic matter into biogas (60–70vol% of methane, CH4), as thereby it also reduces the

  1. Influence of different aerobic pretreatments on the kinetics of anaerobic digestion of olive mill wastewater

    Microsoft Academic Search

    R. Borja; A. Martín; V. Alonso; I. García; C. J. Banks

    1995-01-01

    A kinetic study was carried out on the anaerobic digestion of Olive Mill Wastewater (OMW) and OMW that was previously fermented with Geotrichum candidum, Azotobacter chroococcum and Aspergillus terreus. The bioreactor used was batch fed and contained sepiolite as support for the mediating bacteria. Experimental data observed for methane production (G) against time (t) are described by the following equation:

  2. Integrated treatment of olive oil mill effluents (OME): Study of ozonation coupled with anaerobic digestion

    Microsoft Academic Search

    R. Andreozzi; G. Longo; M. Majone; G. Modesti

    1998-01-01

    The possibility of coupling a chemical treatment (ozonation) with a biological treatment (anaerobic digestion), is investigated for olive oil mill effluents (OME). Preliminary tests showed that both total phenols and unsaturated lipids are reduced to about 50% in 3h of ozonation and that the total COD remains about unvaried. Nevertheless ozonated OME exhibit in general a longer lag phase and

  3. Methane production through anaerobic digestion of various energy crops grown in sustainable crop rotations

    Microsoft Academic Search

    Thomas Amon; Barbara Amon; Vitaliy Kryvoruchko; Andrea Machmüller; Katharina Hopfner-Sixt; Vitomir Bodiroza; Regina Hrbek; Jürgen Friedel; Erich Pötsch; Helmut Wagentristl; Matthias Schreiner; Werner Zollitsch

    2007-01-01

    Biogas production is of major importance for the sustainable use of agrarian biomass as renewable energy source. Economic biogas production depends on high biogas yields. The project aimed at optimising anaerobic digestion of energy crops. The following aspects were investigated: suitability of different crop species and varieties, optimum time of harvesting, specific methane yield and methane yield per hectare. The

  4. Lactate and ethanol as intermediates in two-phase anaerobic digestion

    Microsoft Academic Search

    P. Pipyn; W. Verstraete

    1981-01-01

    The thermodynamics of the various anaerobic digestion patterns of hexose to methane are compared. It appears that by directing the hexose-hydrolysis phase towards ethanol and lactic acid production, methanogenesis can be enhanced because the synthrophic bacteria are allocated more potentially available energy. This hypothesis was confirmed in a series of laboratory tests runs. They revealed that lactic acid and ethanol

  5. Utilization of Re-processed Anaerobically Digested Fiber from Dairy Manure as a Container Media Substrate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The solid fraction (fiber) from the effluent of the anaerobic digestion of dairy manure by plug flow technology yields material that has consistent physical properties (total porosity, air filled porosity at saturation, and water holding capacity) to perform satisfactorily as a plant growth media su...

  6. ANAEROBIC DIGESTION OF FOOD WASTE AND DAIRY MANURE FOR BIOENERGY PRODUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The performance of continuously mixed anaerobic digesters was evaluated in the laboratory for treating manure, food waste and their mixtures at 35 ± 2oC and a hydraulic retention time of 20 days. The first mixture was composed of 32% and 68%, and the second was composed of 48% and 52% food waste and...

  7. Reducing the Anaerobic Digestion Model N1 for its application to an industrial wastewater treatment plant

    E-print Network

    Boyer, Edmond

    the Anaerobic Digestion Model N°1 for its application to an industrial wastewater treatment plant treating winery effluent wastewater Carlos García-Diéguez 1 , Olivier Bernard 2 , Enrique Roca 1, * 1 USC ­ PRODES for winery effluent wastewater. A new reduced stoichiometric matrix was identified and the kinetic parameters

  8. Improvement of anaerobic digester performance by wastewater recirculation through an aerated membrane.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swine wastewater from an anaerobic digester was recirculated through a silicone hose located in an external aeration chamber to determine its effect on wastewater malodorants and biogas composition. The silicone hose acted as a semipermeable membrane for the passage of small molecules. In the first...

  9. Predicting Methane Production Potential of Anaerobic Co-digestion of Swine Manure and Food Waste

    Microsoft Academic Search

    JoungDu Shin; SungSu Han; Ki-Cheol Eom; Shihwu Sung; SangWon Park; Hyunook Kim

    2008-01-01

    Anaerobic co-digestion of swine manure and food waste for biogas production was performed in serum bottles at 2% volatile solids(VS) concen- tration and various mixing ratios of two substrates(swine manure: food waste = 100 : 0 ~ 0 : 100). Through kinetic mode of surface methodology, the methane production was fitted to a Gompertz equation. The specific methane production potential

  10. Removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings

    Microsoft Academic Search

    Ying Yao; Bin Gao; Mandu Inyang; Andrew R. Zimmerman; Xinde Cao; Pratap Pullammanappallil; Liuyan Yang

    2011-01-01

    Biochar converted from agricultural residues or other carbon-rich wastes may provide new methods and materials for environmental management, particularly with respect to carbon sequestration and contaminant remediation. In this study, laboratory experiments were conducted to investigate the removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings (DSTC). Batch adsorption kinetic and equilibrium isotherm experiments

  11. Wastewater polishing by a channelized macrophyte-dominated wetland and anaerobic digestion of the harvested phytomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Constructed wetlands (CW) offer a mechanism to meet regulatory standards for wastewater treatment while minimizing energy inputs. To optimize CW wastewater polishing activities and investigate integration of CW with energy production from anaerobic digestion we constructed a pair of three-tier ch...

  12. Pathogen inactivation in liquid dairy manure during anaerobic and aerobic digestions

    NASA Astrophysics Data System (ADS)

    Biswas, S.; Pandey, P.; Castillo, A. R.; Vaddella, V. K.

    2014-12-01

    Controlling manure-borne pathogens such as E. coli O157:H7, Salmonella spp. and Listeria monocytogenes are crucial for protecting surface and ground water as well as mitigating risks to human health. In California dairy farms, flushing of dairy manure (mainly animal feces and urine) from freestall barns and subsequent liquid-solid manure separation is a common practice for handling animal waste. The liquid manure fraction is generally pumped into the settling ponds and it goes into aerobic and/or anaerobic lagoons for extended period of time. Considering the importance of controlling pathogens in animal waste, the objective of the study was to understand the effects of anaerobic and aerobic digestions on the survival of three human pathogens in animal waste. The pathogen inactivation was assessed at four temperatures (30, 35, 42, and 50 °C), and the relationships between temperature and pathogen decay were estimated. Results showed a steady decrease of E. coli levels in aerobic and anaerobic digestion processes over the time; however, the decay rates varied with pathogens. The effect of temperature on Salmonella spp. and Listeria monocytogenes survival was different than the E. coli survival. In thermophilic temperatures (42 and 50 °C), decay rate was considerable greater compared to the mesophilic temperatures (30 and 35°C). The E. coli log reductions at 50 °C were 2.1 in both aerobic and anaerobic digestions after 13 days of incubation. The Salmonella spp. log reductions at 50 °C were 5.5 in aerobic digestion, and 5.9 in anaerobic digestion. The Listeria monocytogenes log reductions at 50 °C were 5.0 in aerobic digestion, and 5.6 in anaerobic digestion. The log reduction of E. coli, Salmonella spp., and Listeria monocytogens at 30 °C in aerobic environment were 0.1, 4.7, and 5.6, respectively. In anaerobic environment, the corresponding reductions were 0.4, 4.3, and 5.6, respectively. We anticipate that the outcomes of the study will help improving the existing animal waste management processes to control manure-borne pathogens.

  13. Ecological, energetic and economic comparison of anaerobic digestion with different competing technologies to treat biogenic wastes.

    PubMed

    Edelmann, W; Schleiss, K; Joss, A

    2000-01-01

    In order to get more detailed information for better decision making in future biogenic waste treatment, different processes to treat biogenic wastes in plants with a treating capacity of 10,000 tons of organic household wastes per year were compared. The comparison included life cycle assessments as well as economic considerations for different treating methods. Measurements on compost plants showed that methane emissions are higher than estimated so far. With the tools ECOINDICATOR and UBP anaerobic digestion shows to be advantageous as compared to composting, incineration or combination of digestion and composting, mainly because of a better energy balance. In fully enclosed, professional treatment plants, the specific biotechnological treatment costs are in the range of about 150.-sFr/ton for aerobic, anaerobic and combined technologies. It can be concluded, that anaerobic processes will become considerably more important in the future mainly for ecological reasons. PMID:11382001

  14. Characterization and single-stage denitrification anaerobic digestion of spent stream from the hydrolysis-fermentation-combustion process

    NASA Astrophysics Data System (ADS)

    Singh, Ramnik

    The demand for ethanol as an oxygenate and octane booster in automobile fuel is growing. A number of processes are being investigated for conversion of biomass to ethanol. The Hydrolysis-Fermentation-Combustion (HFC) process for fuel ethanol production developed at the University of California Forest Products Laboratory, Richmond, California is at the stage of technology transfer following over two decades of research and development. This study addresses the technology to be used in treatment of spent streams to be discharged from this process. The treatment design combines a single stage denitrification and anaerobic digestion (SSDAD) for the biological treatment of a representative stream from this process. A typical spent stream contained a wide range of soluble organic materials including: unfermented sugars, components of the feedstocks solubilized in the hydrolysis, acid degradation products of carbohydrates, cleavage products of lignin, water-soluble extractives and phenolics, terpenes and other unfermented organic material, and nitrate ion from the nitric acid used as a catalyst in the hydrolysis reaction. Three sets of experiments were conducted in laboratory scale anaerobic digesters. Commonly available anaerobic sludge from local sewage treatment plants was used as a starter seed and was successfully acclimated to the high nitrate substrate leading to enrichment of denitrifiers. Necessary nutrients and trace elements were identified and supplied to satisfy the obligatory requirements of different groups of bacterial groups present. A major finding was the unique role of ammonium hydroxide in controlling pH leading to steady-state operation of the digester. At steady state operation the reduction in COD was 65%, the nitrate reduction was 88% and the nitrite reduction was 100%. Nitrate was reduced to safe nitrogen gas without buildup of any intermediate products. Organic material was converted to useful methane gas and carbon dioxide. The SSDAD system was shown to be effective in treating spent streams having high COD and nitrate concentrations.

  15. Single-stage, batch, leach-bed, thermophilic anaerobic digestion of spent sugar beet pulp.

    PubMed

    Koppar, Abhay; Pullammanappallil, Pratap

    2008-05-01

    Spent sugar beet pulp as received was digested in a single-stage, batch, unmixed, leach-bed, laboratory scale thermophilic anaerobic digester. Biogasification of each 0.450 kg (wet weight) batch of spent pulp was initiated by inoculating with anaerobically digested liquor from previous run. The average methane yield was 0.336 m3 CH4 at STP (kgVS)(-1), the maximum methane production rate was 0.087 m3 CH4 at STP (kgVS)(-1)d(-1), average lag time to initiate methanogenesis was only 0.44 days and time required to achieve 95% methane yield was 8 days. The pH in the digesters ranged between 8.0 and 9.5. High rates of methane generation were sustained even at high pH values. The equivalent organic loading rate in the batch digesters was 4 kgCODm(-3)d(-1). The digestion process used here offers significant improvements over one-stage and two-stage systems reported in the literature with comparable performance as it is a single-stage system where the feedstock does not require size reduction, and mixing is not required in the digester. PMID:17855085

  16. A comparative study of ultrasonic pretreatment and an internal recycle for the enhancement of mesophilic anaerobic digestion.

    PubMed

    Muller, Christopher D; Abu-Orf, Mohammad; Blumenschein, Charles D; Novak, John T

    2009-12-01

    The objective of this study was to investigate the use of ultrasonic energy in an internal recycle and pretreatment mode of operation relative to a conventional mode of mesophilic anaerobic digestion. The primary focus was to determine if using ultrasonics in a pretreatment mode and in an internal recycle line produced changes in performance relative to each other and the control. Using a relatively low-energy sonication system, the data showed that the addition of ultrasonic energy, in either a recycle line or as a pretreatment technology, improved anaerobic digestion efficiency for waste-activated sludge. There was a 13 to 21% increase in biogas yield and an increase in total and volatile solids destruction of 3 to 10.3 additional percentage points, depending on the ultrasonic dose and location. Dewatering of the biosolids following ultrasonic treatment was poorer, as measured by an increase in the optimum polymer conditioning dose. The addition of ultrasonics to the digestion systems generated a more stable biosolids product, with a 2 to 58% reduction in organo-sulfur gas production from dewatered biosolids cakes. PMID:20099624

  17. Modeling anaerobic digestion of blue algae: stoichiometric coefficients of amino acids acidogenesis and thermodynamics analysis.

    PubMed

    Yuan, Xian-Zheng; Shi, Xiao-Shuang; Yuan, Chun-Xin; Wang, Yu-Ping; Qiu, Yan-Ling; Guo, Rong-Bo; Wang, Li-Sheng

    2014-02-01

    In order to facilitate the application of Anaerobic Digestion Model No. 1 (ADM1), an approach for a detailed calculation of stoichiometric coefficients for amino acids acidogenesis during the anaerobic digestion of blue algae is presented. The simulation results obtained support the approach by good predictions of the dynamic behavior of cumulative methane production, pH values as well as the concentrations of acetate, propionate, butyrate, valerate and inorganic nitrogen. The sensitivity analysis based on Monte Carlo simulation showed that the stoichiometric coefficients for amino acids acidogenesis had high sensitivities to the outputs of the model. The model further indicated that the Gibbs free energies from the uptake of long-chain fatty acids (LCFA), valerate and butyrate were positive through the digestion, while the free energies for other components were negative. During the digestion, the cumulative heat productions from microbial activities and methane were 77.69 kJ and 185.76 kJ, respectively. This result suggested that proper heat preservation of anaerobic digesters could minimize the external heating needs due to the heat produced from microbial activities. PMID:24326020

  18. A full-scale study of mixing and foaming in egg-shaped anaerobic digesters.

    PubMed

    Subramanian, Bhargavi; Miot, Alexandre; Jones, Bonnie; Klibert, Corey; Pagilla, Krishna R

    2015-09-01

    Seasonal foaming in full-scale egg-shaped digesters (ESD) at the Oceanside Water Pollution Control Plant was investigated over a two-year period. The causes and contributors of anaerobic digestion (AD) foaming, namely, Gordonia amarae filaments and mixing effects were evaluated in these ESDs. The seasonal presence of high levels of G. amarae as a primary cause and excessive induced mixing as an important contributor of AD foaming has been established. The induced mixing frequency in the ESDs was gradually reduced and eventually shut off in a series of controlled experimental phases. Total solids and temperature profiles indicated that reducing mixing frequency did not significantly impact digester performance or disrupt the homogeneity of digester contents, although it did reduce the occurrence of foam in the digesters. Excessive induced mixing, a contributor to foaming, increased foam events at G. amarae thresholds above 10(6)intersections/mg VSS in the mixed liquor. PMID:26080103

  19. Identification of synergistic impacts during anaerobic co-digestion of organic wastes.

    PubMed

    Astals, S; Batstone, D J; Mata-Alvarez, J; Jensen, P D

    2014-10-01

    Anaerobic co-digestion has been widely investigated, but there is limited analysis of interaction between substrates. The objective of this work was to assess the role of carbohydrates, protein and lipids in co-digestion behaviour separately, and together. Two sets of batch tests were done, each set consisting of the mono-digestion of three substrates, and the co-digestion of seven mixtures. The first was done with pure substrates--cellulose, casein and olive oil--while in the second slaughterhouse waste--paunch, blood and fat--were used as carbohydrate, protein and lipid sources, respectively. Synergistic effects were mainly improvement of process kinetics without a significant change in biodegradability. Kinetics improvement was linked to the mitigation of inhibitory compounds, particularly fats dilution. The exception was co-digestion of paunch with lipids, which resulted in an improved final yield with model based analysis indicating the presence of paunch improved degradability of the fatty feed. PMID:25079207

  20. The use of ultrasound and gamma-irradiation as pre-treatments for the anaerobic digestion of waste activated sludge at mesophilic and thermophilic temperatures.

    PubMed

    Lafitte-Trouqué, S; Forster, C F

    2002-09-01

    The effect of ultrasound and gamma-irradiation used as pre-treatments for the anaerobic digestion of waste activated sludge at both mesophilic and thermophilic temperatures was examined. Untreated activated sludge was also subjected to anaerobic digestion at these temperatures as a control. The sonication time was 90 s using a Soniprep 150 (MSE Scientific Instruments) which operated at 23 kHz and had been adjusted to give an output of 47 W and the gamma-irradiation dose was 500 krad. The digesters were operated in a semi-continuous mode, being fed with fresh sludge every 24 h at hydraulic retention times (HRT) of 8, 10 and 12 days. Over the 24 h period the differences between the digesters, in terms of volatile solids (VS) reductions and biogas production, were not statistically significant for any particular set of conditions. Thermophilic digestion performed better than mesophilic digestion in terms of biogas production, VS reductions (except at HRT of 8 days) and specific methane yields and the optimum retention time was 10 days, at both temperatures. When gas production over the initial eight hours (probably the hydrolytic stage) was examined, it was found that the gas production rates for pre-treated sludges were higher than those for untreated sludges. This was most pronounced at thermophilic temperatures and a HRT of 10 days. Sonication did not affect the numbers of faecal coliforms in the sludge. However, gamma-radiation caused a 3-log reduction and, when coupled with mesophilic digestion, gave a product which contained < 100 g(-1) TS. Thermophilic anaerobic digestion produced sludges which contained < 1 g(-1) TS irrespective of any pre-treatment. PMID:12139327

  1. Application of the IWA ADM1 model to simulate anaerobic co-digestion of organic waste with waste activated sludge in mesophilic condition.

    PubMed

    Derbal, K; Bencheikh-Lehocine, M; Cecchi, F; Meniai, A-H; Pavan, P

    2009-02-01

    Anaerobic digestion model no. 1 model of international water association was applied to a full scale anaerobic co-digestion process for the treatment of the organic fraction of municipal solid wastes along with activated sludge wastes originating from a municipal wastewater treatment plant. This operation was carried out in a digester of 2000 m(3) in volume. It is operates at an average hydraulic retention time of 26.9 days with an average organic loading rate of 1.01 kg TVS/m(3) day, at a temperature of 37 degrees C with an average gas production rate of 0.296 m(3)/m(3) day. The aim of the present study is to compare the results obtained from the simulation with the experimental values. The simulated results showed a good fit for pH, methane and carbon dioxide percentages, biogas volume, chemical oxygen demand, total volatile fatty acids, inorganic nitrogen and inorganic carbon. PMID:18954973

  2. Digestion of thermally hydrolyzed sewage sludge by anaerobic sequencing batch reactor.

    PubMed

    Wang, Zhijun; Wang, Wei; Zhang, Xihui; Zhang, Guangming

    2009-03-15

    Laboratory experiments were conducted to investigate the performance of an anaerobic sequencing batch reactor (ASBR) for the digestion of thermally hydrolyzed sewage sludge. Both mesophilic ASBR and continuous-flow stirred tank reactors (CSTR) were evaluated with an equivalent loading rate of 2.71 kg COD/m(3)day at 20-day hydraulic retention time (HRT) and 5.42 kg COD/m(3)day at 10-day HRT. The average total chemical oxygen demand (TCOD) removals of the ASBR at the 20-day and 10-day HRT were 67.71% and 61.66%, respectively. These were 12.38% and 27.92% higher than those obtained by CSTR. As a result, the average daily gas production of ASBR was 15% higher than that of the CSTR at 20-day HRT, and 31% higher than that of the CSTR at 10-day HRT. Solids in thermally hydrolyzed sludge accumulated within ASBR were able to reach a high steady state with solid content of 65-80 g/L. This resulted in a relatively high solid retention time (SRT) of 34-40 days in the ASBR at 10-day HRT. However, too much solid accumulation resulted in the unsteadiness of the ASBR, making regular discharge of digested sludge from the bottom of the ASBR necessary to keep the reactor stable. The evolution of the gas production, soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in an operation cycle of ASBR also showed that the ASBR was steady and feasible for the treatment of thermally hydrolyzed sludge. PMID:18586392

  3. Effect of feed/inoculum ratio on anaerobic digestion of sonicated sludge.

    PubMed

    Braguglia, C M; Mininni, G; Tomei, M C; Rolle, E

    2006-01-01

    In recent years, relevant interest has been devoted to activated sludge disintegration and solubilisation techniques in order to cope with the biological limitations related to particulate degradation. Mechanical disintegration with ultrasound can efficiently transform insoluble organics into a soluble form: the solubilised organic matter is released from the cells to the bulk phase, thus accelerating the hydrolysis step in the digestion process. Experiments were carried out on bench scale anaerobic reactors fed with either untreated or disintegrated excess sludge, added with a biomass inoculum taken from a full scale anaerobic digester. Digestion tests have been carried out at different feed/inoculum ratios (F/I) in the range of 0.1-2, kinetics of VS reduction has been investigated and a beneficial effect of sonication is observed for all the experimental conditions. Similar beneficial results have also been found for biogas production with a maximum gain of 25% at 0.5 F/I ratio. PMID:17087372

  4. Citrus essential oils and their influence on the anaerobic digestion process: an overview.

    PubMed

    Ruiz, B; Flotats, X

    2014-11-01

    Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24-192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively. PMID:25081855

  5. Anaerobic digestion of municipal solid waste: Analysis of cellulose biodegradative power

    SciTech Connect

    Rivard, C.J.; Nagle, N.J.; Nieves, R.A.; Himmel, M.E. [National Renewable Energy Lab., Golden, CO (United States)

    1993-12-31

    Anaerobic digestion of municipal solid waste (MSW) represents a waste disposal option which results in the production of a gaseous fuel (methane) and an organic residue suitable for use as a soil amendment. The rate limiting step in this process is the hydrolysis of polymeric substrates such as cellulose. Analysis of digester sludge resident cellulase enzyme activity will be discussed. Cellulase enzyme activities are removed from sludge solids by a detergent extraction protocol. The analysis of discrete cellulase activities was accomplished using non-denaturing gel electrophoresis and Zymogram activity staining for CMC activity. Preliminary isolations of discrete cellulase activities from anaerobic digester sludge was performed by preparation isoelectric focussing using the Rainin RF-3 system.

  6. Methanogenic population dynamics during start-up of anaerobic digesters treating municipal solid waste and biosolids

    SciTech Connect

    Griffin, M.E.; McMahon, K.D.; Mackie, R.I.; Raskin, L. [Univ. of Illinois at Urbana, IL (United States)] [Univ. of Illinois at Urbana, IL (United States)

    1998-02-05

    An aggressive start-up strategy was used to initiate codigestion in two anaerobic, continuously mixed bench-top reactors at mesophilic (37 C) and thermophilic (55 C) conditions. The digesters were inoculated with mesophilic anaerobic sewage sludge and cattle manure and were fed a mixture of simulated municipal solid waste and biosolids in proportions that reflect US production rates. The design organic loading rate was 3.1 kg volatile solids/m{sup 3}/day and the retention time was 20 days. Ribosomal RNA-targeted oligonucleotide probes were used to determine the methanogenic community structure in the inocula and the digesters. Chemical analyses were performed to evaluate digester performance. The aggressive start-up strategy was successful for the thermophilic reactor, despite the use of a mesophilic inoculum.

  7. CO{sub 2} level control by anthropogenic peat: The anaerobic digestion of biomass

    SciTech Connect

    Hartung, H.A. [Hartung (H.A.), Collingswood, NJ (United States)

    1995-12-31

    Anthropogenic Peat (AP) has been described as an effective and economical way to control the level of CO{sub 2} in the atmosphere without adverse effect on economic activity and development. All elements of the proposal are separately at work, but one, anaerobic digestion, is not widely known nor has it been applied to biomass as AP requires. Anaerobic digestion is described here, with some of its current large-scale applications. Results of lab studies of the digestion of other materials, including biomass especially grown for this purpose are presented, and the methods used to find them are explained. The preferred biomass source for AP is sugar cane, and extended studies have been run on a close relative, sorghum; preliminary work on cane itself and on various sugar sources is also reported.

  8. Influence of phenylacetic acid pulses on anaerobic digestion performance and archaeal community structure in WWTP sewage sludge digesters.

    PubMed

    Cabrol, Léa; Urra, Johana; Rosenkranz, Francisca; Kroff, Pablo Araya; Plugge, Caroline M; Lesty, Yves; Chamy, Rolando

    2015-01-01

    The effect of phenylacetic acid (PAA) pulses on anaerobic digestion (AD) performance and archaeal community structure was evaluated in anaerobic digesters treating sewage sludge from a wastewater treatment plant (WWTP). Four pilot-scale continuous stirred tank reactors were set up at a full-scale municipal WWTP in Santiago de Chile, and fed with either primary or mixed sewage sludge. AD performance was evaluated by volatile fatty acid (VFA) and biogas production monitoring. Archaeal community structure was characterized by 16S rRNA denaturing gradient gel electrophoresis and band sequencing. In the primary sludge digester, a single PAA pulse at 200 mg L(-1) was sufficient to affect AD performance and archaeal community structure, resulting in long-term VFA accumulation, reduced biogas production and community shift from dominant acetoclastic (Methanosaeta concilii) to hydrogenotrophic (Methanospirillum hungatei) methanogens. By contrast, AD performance and archaeal community structure in the mixed sludge digester were stable and resistant to repeated PAA pulses at 200 and 600 mg L(-1). This work demonstrated that the effect of PAA pulses on methanogenic activity and archaeal community structure differed according to AD substrate, and suggests that better insights of the correlations between archaeal population dynamics and functional performance could help to better face toxic shocks in AD. PMID:26067498

  9. Integration of pyrolysis and anaerobic digestion--use of aqueous liquor from digestate pyrolysis for biogas production.

    PubMed

    Hübner, Tobias; Mumme, Jan

    2015-05-01

    Anaerobic digestion of aqueous pyrolysis liquor derived from pyrolysis of solid digestate was tested in batch mode using an un-adapted inoculum. Three pyrolysis liquors produced at 330°C, 430°C and 530°C in four COD-based concentrations of 3, 6, 12 and 30 g L(-1) were investigated. The three lower concentrations showed considerable biogas production, whereas the 30 g L(-1) dosage caused process inhibition. The highest methane yield of 199.1±18.5 mL g(COD)(-1) (COD removal: 56.9±5.3%) was observed for the 330°C pyrolysis liquor, followed by the 430°C sample with only slightly lower values. The 530°C sample dropped to a yield of 129.3±19.7 mL g(COD)(-1) (COD removal: 36.9±5.6%). Most VOCs contained in the pyrolysis liquor (i.e. furfural, phenol, catechol, guaiacol, and levoglucosan) were reduced below detection limit (cresol by 10-60%). Consequently, integrated pyrolysis and anaerobic digestion in addition to thermochemical conversion of digestate also promises bioconversion of pyrolysis liquors. PMID:25725406

  10. Advanced dynamical risk analysis for monitoring anaerobic digestion process

    Microsoft Academic Search

    Jonathan Hess; Olivier Bernard

    2009-01-01

    Methanogenic fermentation involves a natural ecosystem that can be used for waste water treatment. This anaerobic process can have two locally stable steady-states and an unstable one making the process hard to handle. The aim of this work is to propose analytical criteria in order to detect hazardous working modes, namely situations where the system evolves towards the acidification of

  11. TIME-SETTLEMENT BEHAVIOR OF PROCESSED REFUSE. PART III: ANAEROBIC DIGESTION OF MILLED REFUSE

    EPA Science Inventory

    The objectives of this laboratory investigation were to gain an understanding of the decomposition of milled refuse under anaerobic conditions, the rates of decomposition, and the gas production and composition. The rates of decomposition of cellulose and cellulosic materials, ga...

  12. Application of acidic thermal treatment for one- and two-stage anaerobic digestion of sewage sludge.

    PubMed

    Takashima, M; Tanaka, Y

    2010-01-01

    The effectiveness of acidic thermal treatment (ATT) was examined in a 106-day continuous experiment, when applied to one- or two-stage anaerobic digestion of sewage sludge (4.3% TS). The ATT was performed at 170 °C and pH 5 for 1 hour (sulfuric acid for lowering pH). The one-stage process was mesophilic at 20 days hydraulic retention time (HRT), and incorporated the ATT as pre-treatment. The two-stage process consisted of a thermophilic digester at 5 days HRT and a mesophilic digester at 15 days HRT, and incorporated the ATT as interstage-treatment. On average, VSS reduction was 48.7% for the one-stage control, 65.8% for the one-stage ATT, 52.7% for the two-stage control and 67.6% for the two-stage ATT. Therefore, VSS reduction was increased by 15-17%, when the ATT was combined in both one- and two-stage processes. In addition, the dewaterability of digested sludge was remarkably improved, and phosphate release was enhanced. On the other hand, total methane production did not differ significantly, and color generation was noted in the digested sludge solutions with the ATT. In conclusion, the anaerobic digestion with ATT can be an attractive alternative for sludge reduction, handling, and phosphorus recovery. PMID:21099053

  13. Effect of thermal hydrolysis and ultrasounds pretreatments on foaming in anaerobic digesters.

    PubMed

    Alfaro, N; Cano, R; Fdz-Polanco, F

    2014-10-01

    Foam appears regularly in anaerobic digesters producing operational and safety problems. In this research, based on the operational observation at semi-industrial pilot scale where sludge pretreatment mitigated foaming in anaerobic digesters, this study aimed at evaluating any potential relationship between foaming tools applied to activated sludge at lab-scale (foam potential, foam stability and Microthrix parvicella abundance) and the experimental behavior observed in pilot scale and full-scale anaerobic digesters. The potential of thermal hydrolysis and ultrasounds for reducing foaming capacity was also evaluated. Filamentous bacteria abundance was directly linked to foaming capacity in anaerobic processes. A maximum reduction of M.parvicella abundance (from 5 to 2) was reached using thermal hydrolysis with steam explosion at 170°C and ultrasounds at 66.7kWh/m(3), showing both good anti-foaming properties. On the other hand, foam potential and stability determinations showed a lack of consistency with the bacteria abundance results and experimental evidences. PMID:25168914

  14. Increasing microbial activity in thermophilic anaerobic digestion of physicochemical sludge.

    PubMed

    Tinajero, A; Noyola, A

    2006-01-01

    Two thermophilic lab-scale reactors of 5 L were operated on a daily fed basis. Digester T1 received raw sludge (control) and digester T2 was fed with raw sludge plus metallic micronutrients and a bacilli additive. Raw sludge was obtained from a municipal chemically enhanced primary treatment plant. The effect of additives was clear on methane production, since on day 50, digester T2 produced 900 ml more methane than T1, an increase of 64%. On day 80, T2 reached twice the production of biogas of T1. Volatile solid removal (% VSR) in T2 increased to 29%; while T1 achieved only 15%. Acetic acid concentration in T2 diminished to 100 mg/L, which related to the higher biogas production. Based on the Mexican biosolids standard, the digested sludge reached Class A biosolids, in both digesters: fecal coliforms were reduced to less than 1000 MPN/gTS; Salmonella spp was totally eliminated and helminth egg counts were lower than one viable egg per gram of total solids. PMID:16939109

  15. Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

    PubMed

    Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

    2014-04-01

    The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. PMID:24534902

  16. Microbial community structure and dynamics during anaerobic digestion of various agricultural waste materials.

    PubMed

    Ziganshin, Ayrat M; Liebetrau, Jan; Pröter, Jürgen; Kleinsteuber, Sabine

    2013-06-01

    The influence of the feedstock type on the microbial communities involved in anaerobic digestion was investigated in laboratory-scale biogas reactors fed with different agricultural waste materials. Community composition and dynamics over 2 months of reactors' operation were investigated by amplicon sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Major bacterial taxa belonged to the Clostridia and Bacteroidetes, whereas the archaeal community was dominated by methanogenic archaea of the orders Methanomicrobiales and Methanosarcinales. Correlation analysis revealed that the community composition was mainly influenced by the feedstock type with the exception of a temperature shift from 38 to 55 °C which caused the most pronounced community shifts. Bacterial communities involved in the anaerobic digestion of conventional substrates such as maize silage combined with cattle manure were relatively stable and similar to each other. In contrast, special waste materials such as chicken manure or Jatropha press cake were digested by very distinct and less diverse communities, indicating partial ammonia inhibition or the influence of other inhibiting factors. Anaerobic digestion of chicken manure relied on syntrophic acetate oxidation as the dominant acetate-consuming process due to the inhibition of aceticlastic methanogenesis. Jatropha as substrate led to the enrichment of fiber-degrading specialists belonging to the genera Actinomyces and Fibrobacter. PMID:23624683

  17. Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production

    PubMed Central

    Reza, M. Toufiq; Werner, Maja; Pohl, Marcel; Mumme, Jan

    2014-01-01

    Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 °C) and thermophilic (55 °C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 °C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 LCH4/kgVS (VS: volatile solids) and 121 L CH4/kgVS at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kgdry_biochar was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only. PMID:24962786

  18. Methane and nitrous oxide emissions following anaerobic digestion of sludge in Japanese sewage treatment facilities.

    PubMed

    Oshita, Kazuyuki; Okumura, Takuya; Takaoka, Masaki; Fujimori, Takashi; Appels, Lise; Dewil, Raf

    2014-11-01

    Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases with global warming potentials (expressed in terms of CO2-equivalents) of 28 and 265, respectively. When emitted to the atmosphere, they significantly contribute to climate change. It was previously suggested that in wastewater treatment facilities that apply anaerobic sludge digestion, CH4 continues to be emitted from digested sludge after leaving the anaerobic digester. This paper studies the CH4 and N2O emissions from anaerobically digested sludge in the subsequent sludge treatment steps. Two full-scale treatment plants were monitored over a 1-year period. Average emissions of CH4 and N2O were 509±72 mg/m(3)-influent (wastewater) and 7.1±2.6 mg/m(3)-influent, respectively. These values accounted for 22.4±3.8% of the indirect reduction in CO2-emissions when electricity was generated using biogas. They are considered to be significant. PMID:25194911

  19. Evaluation of integrated anaerobic digestion and hydrothermal carbonization for bioenergy production.

    PubMed

    Reza, M Toufiq; Werner, Maja; Pohl, Marcel; Mumme, Jan

    2014-01-01

    Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 °C) and thermophilic (55 °C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 °C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 LCH4/kgVS (VS: volatile solids) and 121 L CH4/kgVS at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kgdry_biochar was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only. PMID:24962786

  20. Hyperspectral imaging techniques applied to the monitoring of wine waste anaerobic digestion process

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Fabbri, Andrea; Bonifazi, Giuseppe

    2012-11-01

    An anaerobic digestion process, finalized to biogas production, is characterized by different steps involving the variation of some chemical and physical parameters related to the presence of specific biomasses as: pH, chemical oxygen demand (COD), volatile solids, nitrate (NO3-) and phosphate (PO3-). A correct process characterization requires a periodical sampling of the organic mixture in the reactor and a further analysis of the samples by traditional chemical-physical methods. Such an approach is discontinuous, time-consuming and expensive. A new analytical approach based on hyperspectral imaging in the NIR field (1000 to 1700 nm) is investigated and critically evaluated, with reference to the monitoring of wine waste anaerobic digestion process. The application of the proposed technique was addressed to identify and demonstrate the correlation existing, in terms of quality and reliability of the results, between "classical" chemical-physical parameters and spectral features of the digestate samples. Good results were obtained, ranging from a R2=0.68 and a RMSECV=12.83 mg/l for nitrate to a R2=0.90 and a RMSECV=5495.16 mg O2/l for COD. The proposed approach seems very useful in setting up innovative control strategies allowing for full, continuous control of the anaerobic digestion process.

  1. ANAEROBIC DIGESTION OF SWINE MANURE: INHIBITION BY AMMONIA

    Microsoft Academic Search

    KAARE HVID HANSEN; IRINI ANGELIDAKI; BIRGITTE KIÆR AHRING

    1998-01-01

    A stable anaerobic degradation of swine manure with ammonia concentration of 6 g-N\\/litre was obtained in continuously stirred tank reactors with a hydraulic retention time of 15 days, at four different temperatures. Methane yields of 188, 141, 67 and 22 ml-CH4\\/g-VS were obtained at 37, 45, 55 and 60°C, respectively. The yields were significantly lower than the potential biogas yield

  2. Reduction of volatile fatty acids and odor offensiveness by anaerobic digestion and solid separation of dairy manure during manure storage.

    PubMed

    Page, Laura H; Ni, Ji-Qin; Zhang, Hao; Heber, Albert J; Mosier, Nathan S; Liu, Xingya; Joo, Hung-Soo; Ndegwa, Pius M; Harrison, Joseph H

    2015-04-01

    Volatile fatty acids (VFA) play an important role in the biodegradation of organic wastes and production of bioenergy under anaerobic digestion, and are related to malodors. However, little is known about the dynamics of VFA during dairy manure storage. This study evaluated the characteristics of VFA in dairy manure before and after anaerobic co-digestion in a laboratory experiment using eight lab-scale reactors. The reactors were loaded with four different types of dairy manure: (1) liquid dairy manure from a freestall barn, (2) mixture of dairy manure and co-digestion food processing wastes at the inlet of an anaerobic digester, (3) effluent from the digester outlet, and (4) the liquid fraction of effluent from a solid separator. Four VFA (acetic, propionic, butyric, and 2-methylbutyric acids) were identified and quantified in weekly manure samples from all reactors. Results showed that the dominant VFA was acetic acid in all four manure sources. The off-farm co-digestion wastes significantly increased the total VFA concentrations and the proportions of individual VFA in the influent. The dairy manure under storage demonstrated high temporal and spatial variations in pH and VFA concentrations. Anaerobic digestion reduced the total VFA by 86%-96%; but solid-liquid separation did not demonstrate a significant reduction in total VFA in this study. Using VFA as an indicator, anaerobic digestion exhibited an effective reduction of dairy manure odor offensiveness. PMID:25617873

  3. Anaerobic digestion of corn stovers for methane production in a novel bionic reactor.

    PubMed

    Zhang, Meixia; Zhang, Guangming; Zhang, Panyue; Fan, Shiyang; Jin, Shuguang; Wu, Dan; Fang, Wei

    2014-08-01

    To improve the biogas production from corn stovers, a new bionic reactor was designed and constructed. The bionic reactor simulated the rumen digestion of ruminants. The liquid was separated from corn stovers and refluxed into corn stovers again, which simulated the undigested particles separated from completely digested materials and fed back again for further degradation in ruminant stomach. Results showed that the bionic reactor was effective for anaerobic digestion of corn stovers. The liquid amount and its reflux showed an obvious positive correlation with biogas production. The highest biogas production rate was 21.6 ml/gVS-addedd, and the total cumulative biogas production was 256.5 ml/gVS-added. The methane content in biogas ranged from 52.2% to 63.3%. The degradation of corn stovers were greatly enhanced through simulating the animal digestion mechanisms in this bionic reactor. PMID:24923659

  4. A comparison of analytical techniques for evaluating food waste degradation by anaerobic digestion.

    PubMed

    Gómez, X; Cuetos, M J; Tartakovsky, B; Martínez-Núñez, M F; Morán, A

    2010-05-01

    Organic matter contained in food waste was degraded by anaerobic digestion under mesophilic and thermophilic conditions at two hydraulic retention times. Evolution of the digestion process was followed by thermogravimetry analysis, fluorescence spectroscopy and (1)H nuclear magnetic resonance. All analytical methods suggested that longer retention times might be required for food waste stabilization under mesophilic conditions as compared to thermophilic stabilization. All the analytical methods showed that the stabilization process consisted of two steps, where complex organic molecules were formed during initial stabilization and then digested providing sufficient hydraulic retention time. Longer hydraulic retention times were required for food waste stabilization under mesophilic conditions. Overall, thermal and (1)H NMR analyses of the digestate samples might be recommended if more detailed analysis is required, while fluorescence measurements can be used as a fast screening technique, which provides qualitative assessment of the stabilization process. PMID:19548007

  5. Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

    PubMed

    Dumas, C; Perez, S; Paul, E; Lefebvre, X

    2010-04-01

    The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency. PMID:19959355

  6. Effect of moisture of municipal biowaste on start-up and efficiency of mesophilic and thermophilic dry anaerobic digestion.

    PubMed

    Li, Chaoran; Mörtelmaier, Christoph; Winter, Josef; Gallert, Claudia

    2014-09-01

    Methane production from biowaste with 20-30% dry matter (DM) by box-type dry anaerobic digestion and contributing bacteria were determined for incubation at 20, 37 and 55 °C. The same digestion efficiency as for wet anaerobic digestion of biowaste was obtained for dry anaerobic digestion with 20% DM content at 20, 37 and 55 °C and with 25% DM content at 37 and 55 °C. No or only little methane was produced in dry anaerobic reactors with 30% DM at 20, 37 or 55 °C. Population densities in the 20-30% DM-containing biowaste reactors were similar although in mesophilic and thermophilic biowaste reactors with 30% DM content significantly less but phylogenetically more diverse archaea existed. Biogas production in the 20% and 25% DM assays was catalyzed by Methanosarcinales and Methanomicrobiales. In all assays Pelotomaculum and Syntrophobacter species were dominant propionate degraders. PMID:24656488

  7. REACTIVATION AND REGROWTH OF INDICATOR ORGANISMS ASSOCIATED WITH ANAEROBICALLY DIGESTED AND DEWATERED BIOSOLIDS: EPA’S PERSPECTIVE

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  8. Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

    PubMed

    Cazier, E A; Trably, E; Steyer, J P; Escudie, R

    2015-08-01

    In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. PMID:25935390

  9. Enhanced methane production from Taihu Lake blue algae by anaerobic co-digestion with corn straw in continuous feed digesters.

    PubMed

    Zhong, Weizhang; Chi, Lina; Luo, Yijing; Zhang, Zhongzhi; Zhang, Zhenjia; Wu, Wei-Min

    2013-04-01

    Anaerobic digestion of Taihu blue algae was tested in laboratory scale, continuous feed digesters (hydraulic retention time 10 days) at 35°C and various organic loading rates (OLR). The methane production and biomass digestion performed well at OLR below 4.00 gVSL(-1)d(-1) but deteriorated as OLR increased due to the increased ammonia concentration, causing inhibition mainly to acetate and propionate degradation. Supplementing corn straw as co-feedstock significantly improved the digestion performance. The optimal C/N ratio for the co-digestion was 20:1 at OLR of 6.00 gVSL(-1) d(-1). Methane yield of 234 mL CH4 gVS(-1) and methane productivity of 1404 mL CH4 L(-1) d(-1) were achieved with solid removal of 63%. Compared with the algae alone, the methane productivity was increased by 46% with less accumulation of ammonia and fatty acids. The reactor rate-limiting step was acetate and propionate degradation. PMID:23506978

  10. Co-digestion of kitchen waste and fruit-vegetable waste by two-phase anaerobic digestion.

    PubMed

    Yang, Yu-Qiang; Shen, Dong-Sheng; Li, Na; Xu, Dong; Long, Yu-Yang; Lu, Xuan-Yu

    2013-04-01

    The high salinity and fat contents of kitchen waste (KW) inhibits the effect of two-phase anaerobic digestion system. This research introduces fruit-vegetable waste (FVW) to alleviate the inhibition effect caused by salinity and fat concentrations, and tries to achieve an optimal addition ratio of FVW, an optimal hydraulic remain time (HRT) of acidogenic-phase reactor and methanogenic-phase reactor. A two-phase anaerobic digestion (AD) system was developed to co-dispose KW and FVW. Four sets of experiments were run with different mass proportions between KW and FVW (25-75, 50-50, 75-25, and 100-0% m/m). Considering the biodegradation rate and the acidification degree, the system with 25% KW had the best performance during the acidogenic phase. When the system was run with 50% KW, it not only had the best stability performance but also had a bigger capacity to treat KW than the system with 25% KW. The system with 50% KW was the best ratio in this two-phase AD system. Co-digestion of KW and FVW by two-phase AD is feasible. The addition of FVW can reduce the inhibition effect caused by salinity and fat concentrations, reduce the HRT, and lead to a higher degree of acidification. PMID:23288673

  11. Full-stream and part-stream ultrasound treatment effect on sludge anaerobic digestion.

    PubMed

    Pérez-Elvira, S I; Ferreira, L C; Donoso-Bravo, A; Fdz-Polanco, M; Fdz-Polanco, F

    2010-01-01

    The use of ultrasound as pre-treatment to improve anaerobic digestion of secondary sludge has been established as a promising technology. There are great differences between lab scale and full-scale devices, regarding the relationship between the disintegration achieved and the energy supplied. Based on economic aspects, most of the full-scale plants use partial-stream instead of the full-stream sonication, which affects biogas production and digestate dewatering characteristics. A laboratory scale operation combining ultrasound and anaerobic digestion (batch tests) has been performed, determining the relationship between the ratio of sonicated sludge fed and the methane production, SCOD removal and capillary suction time after 20-day anaerobic biodegradation, in order to check the possible benefits of part-stream versus full-stream sonication. Additional incubation was also evaluated, searching for an optimum process combining ultrasound and 24-h incubation pretreatment. Results showed that by sonicating fresh WAS at 25,700 kJ/kg TS biogas yield increased linearly with the percentage of sonicated WAS in the substrate, from 248 (control reactor) to 349 mL CH(4)/g VS (41% increase in full-stream sonication). By incubation (24 h, 55 degrees C), 325 mL CH(4)/g VS were obtained (31% increase), but the digestion of the soluble compounds generated during incubation of sonicated sludge appeared to be less degradable compared to those solubilised by ultrasound or incubation alone, which showed no benefit in combining both treatments. Post-digestion dewatering deteriorated for both part-stream and full-stream sonication, and CST values were constant (74% higher than the control digestate) from 30% to 100% sonicated sludge. PMID:20351414

  12. Study of the operational conditions for anaerobic digestion of urban solid wastes.

    PubMed

    M, Edgar Fernando Castillo; Cristancho, Diego Edison; Arellano, A Victor

    2006-01-01

    This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 degrees C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 degrees C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg(-1) of wet wasteday(-1). Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT. PMID:16321515

  13. Study of the operational conditions for anaerobic digestion of urban solid wastes

    SciTech Connect

    Castillo M, Edgar Fernando [Centro de Estudios e Investigaciones Ambientales, Universidad Industrial de Santander, Calle 9a Carrera 27, Aptdo. Aereo 678, Bucaramanga (Colombia)]. E-mail: efcastil@uis.edu.co; Cristancho, Diego Edison [Centro de Estudios e Investigaciones Ambientales, Universidad Industrial de Santander, Calle 9a Carrera 27, Aptdo. Aereo 678, Bucaramanga (Colombia); Victor Arellano, A. [Centro de Estudios e Investigaciones Ambientales, Universidad Industrial de Santander, Calle 9a Carrera 27, Aptdo. Aereo 678, Bucaramanga (Colombia)

    2006-07-01

    This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 deg. C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 deg. C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg{sup -1} of wet waste day{sup -1}. Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT.

  14. [Anaerobic co-digestion of RSU and macro-algae in the Venice lagoon. Preliminary results].

    PubMed

    Cecchi, F; Pavan, P; Bassetti, A; Farneti, A; Barbaresi, U

    1991-01-01

    In these last few years in the lagoon of Venice the phenomenon of eutrophization has increased. The possibility of turning to an anaerobic digestion of the biomass seems to be interesting. In this view, the following experiment describes a study on the co-digestion of mechanically selected algaebiomass and organic fraction of solid urban waste. The results relevant to both yield parameters and process stability are reported, which have been obtained by monitoring a 3 m3 pilot digestor during a running period of about 85 days, under different working conditions. PMID:1756009

  15. [Enhancement of sewage sludge anaerobic digestibility by thermal hydrolysis pretreatment].

    PubMed

    Wang, Zhi-jun; Wang, Wei

    2005-01-01

    Biochemical methane potential (BMP) experiments of thermo-hydrolyzed sewage sludge are carried out to investigate the effects of thermal hydrolysis on the digestibility of sewage sludge. The results show that thermal hydrolysis pretreatment can facilitate the dissolving of organic solid in sludge, and soluble organics hydrolyzed into low molecular organics, in which volatile fat acids accounted for 30% - 40 % of soluble COD, so the digestibility of sewage sludge remarkably improved. The optimum pretreatment temperature and holding time were 170 degrees C and 30 minutes, under which the total COD removal rate enhanced from original 38.11% to 56.78%, and biogas production rate of COD in feeding sludge from 160mL/g to 250mL/g. PMID:15859411

  16. Anaerobic digestion of solid slaughterhouse waste (SHW) at laboratory scale: Influence of co-digestion with the organic fraction of municipal solid waste (OFMSW)

    Microsoft Academic Search

    María José Cuetos; Xiomar Gómez; Marta Otero; Antonio Morán

    2008-01-01

    Mesophilic anaerobic digestion of slaughterhouse waste (SHW) and its co-digestion with the organic fraction of municipal solid waste (OFMSW) have been evaluated. These processes were carried out in a laboratory plant semi-continuously operated and two set-ups were run. The first set-up, with a hydraulic retention time (HRT) of 25 days and organic loading rate (OLR) of 1.70kgVSm?3day?1 for digestion, and

  17. Experimental and modeling study of a two-stage pilot scale high solid anaerobic digester system.

    PubMed

    Yu, Liang; Zhao, Quanbao; Ma, Jingwei; Frear, Craig; Chen, Shulin

    2012-11-01

    This study established a comprehensive model to configure a new two-stage high solid anaerobic digester (HSAD) system designed for highly degradable organic fraction of municipal solid wastes (OFMSW). The HSAD reactor as the first stage was naturally separated into two zones due to biogas floatation and low specific gravity of solid waste. The solid waste was retained in the upper zone while only the liquid leachate resided in the lower zone of the HSAD reactor. Continuous stirred-tank reactor (CSTR) and advective-diffusive reactor (ADR) models were constructed in series to describe the whole system. Anaerobic digestion model No. 1 (ADM1) was used as reaction kinetics and incorporated into each reactor module. Compared with the experimental data, the simulation results indicated that the model was able to well predict the pH, volatile fatty acid (VFA) and biogas production. PMID:22989632

  18. Anaerobic digestion of antibiotic residue in combination with hydrothermal pretreatment for biogas.

    PubMed

    Zhang, Guangyi; Li, Chunxing; Ma, Dachao; Zhang, Zhikai; Xu, Guangwen

    2015-09-01

    Antibiotic residues are difficult to be treated or utilized because of their high water content and residual antibiotics. This article is devoted to investigating the possibility of biogas production from cephalosporin C residue (CPCAR), one typical type of antibiotic residues, via anaerobic digestion in combination with hydrothermal pretreatment (HTPT). The results from the bench-scale experiments showed that the combination of HTPT and anaerobic digestion can provide a viable way to convert CPCAR into biogas, and the biogas and methane yields reached 290 and 200ml(gTS)(-1), respectively. This article further evaluated the proposed technology in terms of energy balance and technical feasibility based on theoretical calculation using the data from a pilot HTPT test. It was shown that the process is totally self-sufficient in energy and its main challenging problem of ammonia inhibition can be solved via ammonia stripping. PMID:26038331

  19. Electrochemical treatment of anaerobic digestion effluent using a Ti/Pt-IrO2 electrode.

    PubMed

    Lei, Xiaohui; Maekawa, Takaaki

    2007-12-01

    Electrochemical treatment of the anaerobic digestion effluents using a Ti/Pt-IrO(2) electrode was evaluated in this study. The effects of electric current, NaCl dosage, and initial pH on ammonia, nitrate, total organic carbon (TOC), inorganic carbon (IC), final pH, and turbidity variations were studied in a series of batch experiments. It was found that the electric current and NaCl dosage had a considerably larger effect on the oxidization of ammonia; this was less for the effect of the initial pH. In addition, electroflotation was the main mechanism for turbidity, TOC, and IC removals. Further, the IC removal was mainly affected by the pH of wastewater. The electrochemical treatment using Ti/Pt-IrO(2) electrode without pretreatment was feasible for the anaerobic digestion effluent. PMID:17207618

  20. Characterization and environmental studies of Pompano Beach anaerobic digestion facility. Annual report

    SciTech Connect

    Sengupta, S; Gerrish, H P; Wong, K F; Nemerow, N; Daly, Jr, E L; Farooq, S; Chriswell, C

    1980-08-01

    Municipal solid wastes contain numerous substances of potential environmental concern. While some understanding of the composition of raw municipal waste and its leachate products is available, no information regarding characteristics of solid, liquid and gaseous outputs from anaerobic digestion exists. If centralized anaerobic digestion plants are to be environmentally viable, the characteristics and environmental effects of effluents from these plants must be acceptable. The environmental concerns are particularly acute where ground water supplies are precariously low and the water table is high, South Florida is such a location. A characterization and environmental study was initiated by the Resource Recovery Group on August 1978. The specific objectives are: (1) systematic characterization of solid, liquid and gaseous inputs and outputs; (2) investigations of leaching characteristic of output solid and liquid effluents, and the transport of pollutants to and through ground water systems; and (3) analysis of environmental and process parameters to obtain causal relationships.

  1. WASTEWATER reclamation and methane production using water hyacinth and anaerobic digestion

    SciTech Connect

    Chynoweth, D.P.; DoLenc, D.A.; Reddy, K.R.; Schwegler, B.

    1983-06-01

    This paper describes the results of research in progress to evaluate the technical and economic feasibility of utilizing water hyacinth ponds for treatment of domestic wastewater and the utilization of anaerobic digestion for conversion of the hyacinth crop and primary sludge to methane. The system concept illustrated in Figure I employs water hyacinth ponds for secondary and tertiary treatment of effluent from primary treatment (which removes settleable solids). Primary effluent supernatant is passed through water hyacinth ponds which effect organic and nutrient reduction. Collected primary sludge and harvested hyacinth are added as a blend to the anaerobic digestion process where a portion of the organic matter is converted to methane and carbon dioxide. The methane is separated from the carbon dioxide and used as an energy product.

  2. Biological treatment of anaerobically digested palm oil mill effluent (POME) using a Lab-Scale Sequencing Batch Reactor (SBR)

    Microsoft Academic Search

    Yi Jing Chan; Mei Fong Chong; Chung Lim Law

    2010-01-01

    The production of highly polluting palm oil mill effluent (POME) has resulted in serious environmental hazards. While anaerobic digestion is widely accepted as an effective method for the treatment of POME, anaerobic treatment of POME alone has difficulty meeting discharge limits due to the high organic strength of POME. Hence, subsequent post-treatment following aerobic treatment is vital to meet the

  3. Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

    PubMed Central

    Jin, Jingwei; Dai, Xiaohu

    2014-01-01

    The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

  4. Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

    PubMed

    Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

    2014-01-01

    The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

  5. Anaerobic digestion of cattle waste at mesophilic and thermophilic temperatures

    Microsoft Academic Search

    R. I. Mackie; M. P. Bryant

    1995-01-01

    Methanogenesis was studied using stirred, bench-top fermentors of 3-1 working volume fed on a semi-continuous basis with waste obtained from cattle fed a high grain, finishing diet. Digestion was carried out at 40 and 60°C. CH4 production was 11.8, 18.3, 61.9 and 84.5% higher in the thermophilic than the mesophilic digestor at the 3, 6, 9 and 12 g volatile

  6. Environmental assessment of farm-scaled anaerobic co-digestion for bioenergy production.

    PubMed

    Lijó, Lucía; González-García, Sara; Bacenetti, Jacopo; Negri, Marco; Fiala, Marco; Feijoo, Gumersindo; Moreira, María Teresa

    2015-07-01

    The aim of this study was to assess the environmental profile of a bioenergy system based on a co-digestion plant using maize silage and pig slurry as substrates. All the processes involved in the production of bioenergy as well as the avoided processes accrued from the biogas production system were evaluated. The results evidenced the environmental importance of the cultivation step and the environmental credits associated to the avoided processes. In addition, this plant was compared with two different plants that digest both substrates separately. The results revealed the environmental benefits of the utilisation of pig slurry due to the absence of environmental burdens associated with its production as well as credits provided when avoiding its conventional management. The results also presented the environmental drawbacks of the utilisation of maize silage due to the environmental burdens related with its production. Accordingly, the anaerobic mono-digestion of maize silage achieved the worst results. The co-digestion of both substrates was ranked in an intermediate position. Additionally, three possible digestate management options were assessed. The results showed the beneficial effect of digestate application as an organic fertiliser, principally on account of environmental credits due to avoided mineral fertilisation. However, digestate application involves important acidifying and eutrophicating emissions. PMID:25892438

  7. Escherichia coli inactivation kinetics in anaerobic digestion of dairy manure under moderate, mesophilic and thermophilic temperatures

    PubMed Central

    2011-01-01

    Batch anaerobic digestion experiments using dairy manure as feedstocks were performed at moderate (25°C), mesophilic (37°C), and thermophilic (52.5°C) temperatures to understand E. coli, an indicator organism for pathogens, inactivation in dairy manure. Incubation periods at 25, 37, and 52.5°C, were 61, 41, and 28 days respectively. Results were used to develop models for predicting E. coli inactivation and survival in anaerobic digestion. For modeling we used the decay of E. coli at each temperature to calculate the first-order inactivation rate coefficients, and these rates were used to formulate the time - temperature - E. coli survival relationships. We found the inactivation rate coefficient at 52.5°C was 17 and 15 times larger than the inactivation rate coefficients at 25 and 37°C, respectively. Decimal reduction times (D10; time to achieve one log removal) at 25, 37, and 52.5°C, were 9 -10, 7 - 8 days, and < 1 day, respectively. The Arrhenius correlation between inactivation rate coefficients and temperatures over the range 25 -52.5°C was developed to understand the impacts of temperature on E. coli inactivation rate. Using this correlation, the time - temperature - E. coli survival relationships were derived. Besides E. coli inactivation, impacts of temperature on biogas production, methane content, pH change, ORP, and solid reduction were also studied. At higher temperatures, biogas production and methane content was greater than that at low temperatures. While at thermophilic temperature pH was increased, at mesophilic and moderate temperatures pH were reduced over the incubation period. These results can be used to understand pathogen inactivation during anaerobic digestion of dairy manure, and impacts of temperatures on performance of anaerobic digesters treating dairy manure. PMID:21906374

  8. Feasibility of biohydrogen production by anaerobic co-digestion of food waste and sewage sludge

    Microsoft Academic Search

    Sang-Hyoun Kim; Sun-Kee Han; Hang-Sik Shin

    2004-01-01

    Anaerobic co-digestion of food waste and sewage sludge for hydrogen production was performed in serum bottles under various volatile solids (VS) concentrations (0.5–5.0%) and mixing ratios of two substrates (0:100–100:0, VS basis). Through response surface methodology, empirical equations for hydrogen evolution were obtained. The specific hydrogen production potential of food waste was higher than that of sewage sludge. However, hydrogen

  9. Applications of Anammox based processes to treat anaerobic digester supernatant at room temperature

    Microsoft Academic Search

    Jose Vázquez-Padín; Isaac Fernádez; Mónica Figueroa; Anuska Mosquera-Corral; Jose-Luis Campos; Ramón Méndez

    2009-01-01

    The supernatant of an anaerobic digester was treated at 20°C in two systems. The first one is a two units configuration, conformed by two sequencing batch reactors (SBR), carrying out partial nitrification and Anammox processes, respectively. Partial nitrification was achieved by granular biomass with a mean diameter of 3mm, operating at a dissolved oxygen concentration of 2.7mg\\/L. The combined system

  10. Effect of aluminium and sulphate on anaerobic digestion of sludge from wastewater enhanced primary treatment

    Microsoft Academic Search

    N. Cabirol; E. J. Barragán; A. Durán; A. Noyola

    2003-01-01

    The combined and individual effects of aluminium and sulphate at concentrations of 1,000 mg\\/l as Al(OH)3, and 150 mgSO42-\\/L as K2SO4, respectively, on the anaerobic digestion of sludge from enhanced primary treatment (EPT) were evaluated in 1 L capacity semi continuous reactors. It was found that at 59 days, aluminium inhibits the specific methanogenic activity (SMA) of methanogenic and acetogenic

  11. Mechanism of inhibition caused by long-chain fatty acids in anaerobic digestion process

    Microsoft Academic Search

    Keisuke Hanaki; Tomonori Matsuo; Michihiko Nagase

    1981-01-01

    The inhibitory effect of long-chain fatty acids on the anaerobic digestion process was examined in batch experiments using synthetic substrates. The addition of long-chain fatty acids caused the appearance of the lag period in the methane production from acetate and in the degradation of both long-chain fatty acids and n-butyrate. Methane production from hydrogen proceeded without lag period although its

  12. Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite

    Microsoft Academic Search

    I. Angelidaki; S. P. Petersen; B. K. Ahring

    1990-01-01

    The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaption of the digestors, very rapid

  13. Bacteria and archaea involved in anaerobic digestion of distillers grains with solubles

    Microsoft Academic Search

    Ayrat M. Ziganshin; Thomas Schmidt; Frank Scholwin; Olga N. Il’inskaya; Hauke Harms; Sabine Kleinsteuber

    2011-01-01

    Cereal distillers grains, a by-product from bioethanol industry, proved to be a suitable feedstock for biogas production in\\u000a laboratory scale anaerobic digesters. Five continuously stirred tank reactors were run under constant conditions and monitored\\u000a for biogas production and composition along with other process parameters. Iron additives for sulfide precipitation significantly\\u000a improved the process stability and efficiency, whereas aerobic pretreatment of

  14. Temperature-phased anaerobic digestion (TPAD) to obtain class A biosolids: A semi-continuous study

    Microsoft Academic Search

    Víctor Riau; M. Ángeles De la Rubia; Montserrat Pérez

    2010-01-01

    Regulations regarding the land application of sewage sludge require the performance of highly efficient treatments for pathogen reduction, such as temperature-phased anaerobic digestion (TPAD). Several semi-continuous experiments with different solid residence times (SRTs) have been made to find the best combination – TPAD 15\\/15, TPAD 5\\/15, TPAD 3\\/15 or TPAD 3\\/12. TPAD systems showed better performance in terms of VS

  15. Effect of COD\\/Sulfate Ratios on Batch Anaerobic Digestion Using Sulfate-Reduction Bacteria

    Microsoft Academic Search

    Heng-heng Cao; Hong-guo Zhang; Ding-gui Luo; Yong-heng Chen

    2011-01-01

    A study on effects of the COD\\/sulfate ratio on characteristics of sulfate-reduction bacteria (SRB) in activated sludge of a UASB reactor was performed in batch anaerobic digestion experiment. Changes of pH in samples were 7.22~8.17 which was beneficial to the growth of SRB with high sulfate removal efficiency. Sulfate reduction efficiencies of COD\\/sulfate ratios from 0.43 to 3.03 were 18.7(R1),

  16. Anaerobic Digestion of Vegetable Wastes for Biogas Production in a Fed-Batch Reactor

    Microsoft Academic Search

    B. Velmurugan; R. Alwar Ramanujam

    2011-01-01

    Vegetable wastes (Banana stem, Cabbage and Ladies finger) were an-aerobically digested in a fed-batch laboratory scale reactor at mesophilic conditions (35 o c). The Organic Loading Rate (OLR) was maintained at 2.25 g\\/l.d with a Hydraulic Retention Time (HRT) of 30 days. The average methane content in the biogas was 65% and the Methane yield was 0.387 l CH4\\/g VS

  17. Electrochemical treatment of anaerobic digestion effluent using a Ti\\/Pt–IrO 2 electrode

    Microsoft Academic Search

    Xiaohui Lei; Takaaki Maekawa

    2007-01-01

    Electrochemical treatment of the anaerobic digestion effluents using a Ti\\/Pt–IrO2 electrode was evaluated in this study. The effects of electric current, NaCl dosage, and initial pH on ammonia, nitrate, total organic carbon (TOC), inorganic carbon (IC), final pH, and turbidity variations were studied in a series of batch experiments. It was found that the electric current and NaCl dosage had

  18. Anaerobic digestion of municipal solid waste in a nonmixed solids concentrating digestor

    Microsoft Academic Search

    T. H. Chen; P. Chynoweth; R. BIljetina

    1990-01-01

    This paper reports on the performance and characteristics of a 4.5 m3 nonmixed, vertical flow Experimental anaerobic digestion Test Unit (ETU) treating refuse-derived fuel (RDF) and primary sludge.\\u000a It was operated at 35°C and a loading rate of 3.2 kg VS\\/m3\\/d. Three tests involving chemical nutrients addition or effluent supernatant recycle were completed. Hydraulic retention\\u000a times were 16, 18, and

  19. Enhanced anaerobic digestion of piggery wastewater by ammonia stripping: Effects of alkali types

    Microsoft Academic Search

    Lei Zhang; Deokjin Jahng

    2010-01-01

    Air stripping at alkaline pH was carried out to remove ammonia from the piggery wastewater, and its effects on subsequent anaerobic digestion were investigated in semi-continuous experiments. In ammonia stripping process, three alkalis (NaOH, KOH and CaO) were used for pH adjustment. When using NaOH and KOH, the methane production rate increased more than two folds as compared to the

  20. Effects of free long-chain fatty acids on thermophilic anaerobic digestion

    Microsoft Academic Search

    I. Angelidaki; B. K. Ahring

    1992-01-01

    Summary Low concentrations of the long-chain fatty acids oleate and stearate inhibited all steps of the anaerobic thermophilic biogas process during digestion of cattle manure. The lag phase increased when the concentrations of oleate and stearate were 0.2 g\\/l and 0.5 g\\/l, respectively, and no growth was found at concentrations of 0.5 g\\/l for oleate and 1.0 g\\/l for stearate.

  1. Comparative process stability and efficiency of anaerobic digestion; mesophilic vs. thermophilic

    Microsoft Academic Search

    Moonil Kim; Young-Ho Ahn; R. E Speece

    2002-01-01

    The comparative process stability and efficiency of mesophilic (35°C) and thermophilic anaerobic digestion (55°C) has been evaluated for four different reactor configurations, which are: daily batch-fed single-stage continuously stirred tank reactor (CSTR), continuously fed single-stage CSTR, daily batch-fed two-phase CSTR, and daily batch-fed non-mixed single-stage reactor. The results are discussed for three periods: (1) start-up, (2) steady state, and (3)

  2. Influence of substrate concentration on the macroenergetic parameters of anaerobic digestion of black-olive wastewater

    Microsoft Academic Search

    R. Borja; A. Garrido; A. Martin; V. Alonso

    1994-01-01

    The macroenergetic parameters of the anaerobic digestion of black-olive wastewater, i.e. the yield coefficient for the biomass (Y. g VSS\\/g COD) and the specific rate of substrate uptake for cell maintenance (m, g COD\\/g VSS-day) decreased 6 limes and increased 5 times. respectively, when the influent substrate concentration increased from 1.1 to 4.4 g COD\\/l. This was significant at 95%

  3. Mathematical modeling of non-ideal mixing continuous flow reactors for anaerobic digestion of cattle manure.

    PubMed

    Keshtkar, A; Meyssami, B; Abolhamd, G; Ghaforian, H; Asadi, M Khalagi

    2003-03-01

    Most conventional digesters used for animal wastewater treatment include continuously stirred-tank reactors. While imperfect mixing patterns are more common than ideal ones in real reactors, anaerobic digestion models often assume complete mixing conditions. Therefore, their applicability appears to be limited. In this study, a mathematical model for anaerobic digestion of cattle manure was developed to describe the dynamic behavior of non-ideal mixing continuous flow reactors. The microbial kinetic model includes an enzymatic hydrolysis step and four microbial growth steps, together with the effects of substrate inhibition, pH and thermodynamic considerations. The biokinetic expressions were linked to a simple two-region liquid mixing model, which considered the reactor volume in two separate sections, the flow-through and the retention regions. Deviations from an ideal completely mixed regime were represented by changing the relative volume of the flow-through region (a) and the ratio of the internal exchange flow rate to the feed flow rate (b). The effects of the hydraulic retention time, the composition of feed, the initial conditions of the reactor and the degree of mixing on process performance can be evaluated by the dynamic model. The simulation results under different conditions showed that deviations from the ideal mixing regime decreased the methane yield and resulted in a reduced performance of the anaerobic reactors. The evaluation of the impact of the characteristic mixing parameters (a) and (b) on the anaerobic digestion of cattle manure showed that both liquid mixing parameters had significant effects on reactor performance. PMID:12733584

  4. Chlorella pyrenoidosa cultivation using anaerobic digested starch processing wastewater in an airlift circulation photobioreactor.

    PubMed

    Tan, Xiaobo; Chu, Huaqiang; Zhang, Yalei; Yang, Libin; Zhao, Fangchao; Zhou, Xuefei

    2014-10-01

    To explore the integration of microalgae cultivation and anaerobic processing for wastewater treatment, we utilized an airlift circulation photobioreactor and a dynamic membrane reactor for microalgae cultivation in combination with an upflow anaerobic sludge bed (UASB) reactor for starch processing wastewater (SPW) treatment. Chlorella pyrenoidosa completely adapted to the digested SPW without any chemical additives, and it grew normally under a wide temperature range in different seasons. C. pyrenoidosa was always the dominant microorganism in the photobioreactors although bacteria and some wild type microalgae were observed. Optimal biomass growth and pollutants removal was achieved at temperatures between 35 and 38°C in summer, removing 65.99% of COD, 83.06% of TN, 96.97% of TP and a biomass productivity of 0.37gL(-1)d(-1). Temperature fluctuation significantly influenced lipid contents and FAMEs compositions in biomass. The results demonstrate the successful integration of microalgae biomass production and anaerobic processing for wastewater treatment. PMID:25164347

  5. Gas in the Digestive Tract

    MedlinePLUS

    ... is primarily composed of carbon dioxide, oxygen, nitrogen, hydrogen, and sometimes methane. Flatus, gas passed through the ... by bacteria in the large intestine, which release hydrogen and carbon dioxide in the process. Other types ...

  6. Start-Up of an Anaerobic Dynamic Membrane Digester for Waste Activated Sludge Digestion: Temporal Variations in Microbial Communities

    PubMed Central

    Yu, Hongguang; Wang, Qiaoying; Wang, Zhiwei; Sahinkaya, Erkan; Li, Yongli; Ma, Jinxing; Wu, Zhichao

    2014-01-01

    An anaerobic dynamic membrane digester (ADMD) was developed to digest waste sludge, and pyrosequencing was used to analyze the variations of the bacterial and archaeal communities during the start-up. Results showed that bacterial community richness decreased and then increased over time, while bacterial diversity remained almost the same during the start-up. Proteobacteria and Bacteroidetes were the major phyla. At the class level, Betaproteobacteria was the most abundant at the end of start-up, followed by Sphingobacteria. In the archaeal community, richness and diversity peaked at the end of the start-up stage. Principle component and cluster analyses demonstrated that archaeal consortia experienced a distinct shift and became stable after day 38. Methanomicrobiales and Methanosarcinales were the two predominant orders. Further investigations indicated that Methanolinea and Methanosaeta were responsible for methane production in the ADMD system. Hydrogenotrophic pathways might prevail over acetoclastic means for methanogenesis during the start-up, supported by specific methanogenic activity tests. PMID:24695488

  7. Do anaerobic digestates promote dispersion, acidification and water repellency in soils?

    NASA Astrophysics Data System (ADS)

    Voelkner, Amrei; Holthusen, Dörthe; Horn, Rainer

    2014-05-01

    Digestates are used as organic fertilizer on agricultural land due to their high amounts of nutrients (e.g. potassium, sodium). It is commonly expected that the application of sludge derived from anaerobic digestion can influence the soil structure and soil stability. Due to the fact that digestates contain large quantities of monovalent salts and long-chained fatty acids, the consequence of sludge amendment can be soil degradation caused by acidification, dispersion and increased water-repellency. Thus, water infiltration can be impeded which results in a preservation of stable soil aggregates. However, a diminished water infiltration can support water erosion and preferential flow of easy soluble nutrients into the groundwater. Our research was conducted with different digestates derived from maize, wheat and sugar beet to examine occurring processes in soils of two different textures after the application of anaerobic sludges. Particularly, we focused on the wetting properties of the soil. For this purpose, the wetting behavior was investigated by determining the sorptivity-based Repellency Index with moist samples and the contact angle with homogenized, air-dried soil material. Further surveys were carried out to assess the flow behavior of digestates application and the deformation of the particle-to-particle association by microscaled shearing. Additionally, the acidification process in the soil as a result of sludge application was investigated. To account for the dispersive impact of digestates, the turbidity of soil suspensions was ascertained. We summarize from the results that the digestates have a clear impact on the water repellency of the soil. We recognized a shift to more hydrophobic conditions. Partially, the pH remains on a high level due to the alkaline digestate, but several samples show a decline of pH, depending on the soil texture, respectively. However, soil structure was weakened as was shown by an increase of turbidity. As a conclusion, we point out the necessity to take into account the impact which anaerobic digestates might have on soil structure and stability in addition to their fertilizing effect to sustain the soil in a good state.

  8. Semi-continuous mesophilic anaerobic digester performance under variations in solids retention time and feeding frequency.

    PubMed

    Manser, Nathan D; Mihelcic, James R; Ergas, Sarina J

    2015-08-01

    The goal of this research was to understand the effect of solids retention time (SRT) and feeding frequency on the performance of anaerobic digesters used to recover bioenergy from swine waste. Semi-continuous mesophilic anaerobic digesters were operated at varying SRTs and feeding frequencies. Performance metrics included biogas and methane production rates, biomass robustness and functionality and removals of volatile solids, soluble chemical oxygen demand, the fecal-indicator bacteria Escherichia coli, and the human pathogen Salmonella. Biochemical methane formation potential and specific methanogenic activity assays were used to demonstrate biomass robustness and functionality. Results indicated that anaerobic digesters fed weekly had higher average methane yields (0.20 vs. 0.18m(3)CH4/kg-VSadded), specific methanogenic activities (40 vs. 35ml/day), and fecal indicator bacteria destruction (99.9% vs. 99.4%) than those fed every-other day. Salmonella, soluble COD, and VS destruction did not change with varied feeding frequency; however, higher removals were observed with longer SRT. PMID:25965953

  9. Modular expert system for the diagnosis of operating conditions of industrial anaerobic digestion plants.

    PubMed

    Lardon, L; Puñal, A; Martinez, J A; Steyer, J P

    2005-01-01

    Anaerobic digestion (AD) plants are highly efficient wastewater treatment processes with possible energetic valorisation. Despite these advantages, many industries are still reluctant to use them because of their instability in the face of changes in operating conditions. To the face this drawback and to enhance the industrial use of anaerobic digestion, one solution is to develop and to implement knowledge base (KB) systems that are able to detect and to assess in real-time the quality of operating conditions of the processes. Case-based techniques and heuristic approaches have been already tested and validated on AD processes but two major properties were lacking: modularity of the system (the knowledge base system should be easily tuned on a new process and should still work if one or more sensors are added or removed) and uncertainty management (the assessment of the KB system should remain relevant even in the case of too poor or conflicting information sources). This paper addresses these two points and presents a modular KB system where an uncertain reasoning formalism is used to combine partial and complementary fuzzy diagnosis modules. Demonstration of the interest of the approach is provided from real-life experiments performed on an industrial 2,000 m3 CSTR anaerobic digester. PMID:16180460

  10. Changes in bacterial communities from anaerobic digesters during petroleum hydrocarbon degradation.

    PubMed

    Scherr, Kerstin E; Lundaa, Tserennyam; Klose, Viviana; Bochmann, Günther; Loibner, Andreas P

    2012-02-20

    Anaerobic biodegradation of petroleum hydrocarbons (PHC) to methane has been recognized to occur in oil reservoirs and contaminated surface sites alike. This process could be employed efficiently for the treatment of contaminated materials, including petrochemical wastes and PHC-contaminated soil, since no external electron acceptor is required. Moreover, the controlled production of methane in digestion plants, similarly to the anaerobic digestion (AD) of energy crops or organic residues, would enable for energy recovery from these wastes. At present, little is known about the bacterial communities involved in and responsible for hydrocarbon fermentation, the initial step in PHC conversion to methane. In the present study, the fate of two different methanogenic communities derived from the AD of wastewater (WWT) and of biowaste, mixed with PHC-contaminated soil (SWT), was monitored during incubation with PHC using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA genes amplified with Bacteria-specific primers. During 11 months of incubation, slight but significant degradation of PHC occurred in both sludges and distinct bacterial communities were developing. In both sludges, Bacteroidetes were found. In addition, in WWT, the bacterial community was found to be dominated by Synergistetes and Proteobacteria, while Firmicutes and unidentified members were abundant in SWT. These results indicate that bacterial communities from anaerobic digesters can adapt to and degrade petroleum hydrocarbons. The decontamination of PHC-containing waste via fermentative treatment appears possible. PMID:21939698

  11. Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano

    SciTech Connect

    Alvarez, Rene [IIDEPROQ, UMSA, Plaza del Obelisco 1175, La Paz (Bolivia)], E-mail: Rene.alvarez@iideproq.org; Liden, Gunnar [Department of Chemical Engineering, Lund University, P.O. Box 124, 221 00 Lund (Sweden)

    2008-07-01

    Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure from llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-l reactors at a temperature of 25 deg. C with 30 days of hydraulic retention time (HRT) and an organic loading rate (OLR) of 1.8 kg VS m{sup -3} d{sup -1}. Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process.

  12. Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano.

    PubMed

    Alvarez, René; Lidén, Gunnar

    2008-01-01

    Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure from llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-l reactors at a temperature of 25 degrees C with 30 days of hydraulic retention time (HRT) and an organic loading rate (OLR) of 1.8 kg VS m(-3) d(-1). Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process. PMID:18155895

  13. Life cycle assessment of energy from waste via anaerobic digestion: a UK case study.

    PubMed

    Evangelisti, Sara; Lettieri, Paola; Borello, Domenico; Clift, Roland

    2014-01-01

    Particularly in the UK, there is potential for use of large-scale anaerobic digestion (AD) plants to treat food waste, possibly along with other organic wastes, to produce biogas. This paper presents the results of a life cycle assessment to compare the environmental impacts of AD with energy and organic fertiliser production against two alternative approaches: incineration with energy production by CHP and landfill with electricity production. In particular the paper investigates the dependency of the results on some specific assumptions and key process parameters. The input Life Cycle Inventory data are specific to the Greater London area, UK. Anaerobic digestion emerges as the best treatment option in terms of total CO2 and total SO2 saved, when energy and organic fertiliser substitute non-renewable electricity, heat and inorganic fertiliser. For photochemical ozone and nutrient enrichment potentials, AD is the second option while incineration is shown to be the most environmentally friendly solution. The robustness of the model is investigated with a sensitivity analysis. The most critical assumption concerns the quantity and quality of the energy substituted by the biogas production. Two key issues affect the development and deployment of future anaerobic digestion plants: maximising the electricity produced by the CHP unit fuelled by biogas and to defining the future energy scenario in which the plant will be embedded. PMID:24112851

  14. Making lignin accessible for anaerobic digestion by wet-explosion pretreatment.

    PubMed

    Ahring, Birgitte K; Biswas, Rajib; Ahamed, Aftab; Teller, Philip J; Uellendahl, Hinrich

    2014-10-23

    Lignin is a major part of the recalcitrant fraction of lignocellulose and in nature its degradation occurs through oxidative enzymes along with microbes mediated oxidative chemical actions. Oxygen assisted wet-explosion pretreatment promotes lignin solubility and leads to an increase biodegradation of lignin during anaerobic digestion processes. The pretreatment of feedlot manure was performed in a 10L reactor at 170°C for 25min using 4bars oxygen and the material was fed to a continuous stirred tank reactor operated at 55°C for anaerobic digestion. Methane yield of untreated and pretreated material was 70±27 and 320±36L/kg-VS/Day, respectively, or 4.5 times higher yield as a result of the pretreatment. Aliphatic acids formed during the pretreatment were utilized by microbes. 44.4% lignin in pretreated material was actually converted in the anaerobic digestion process compared to 12.6% for untreated material indicating the oxygen assisted explosion promoted lignin degradation. PMID:25459820

  15. Anaerobic digestion of poultry wastes and algae production from digester effluent

    Microsoft Academic Search

    W. Turnacliff; V. Kollman; D. Rockey

    1978-01-01

    Results obtained in the biosynthesis of methane from poultry manures and the growth of algae on the digester effluent were reported. The algae would be used as a feed supplement for the poultry. The performance of the digester system as a poultry manure handling and disposal system was very good, but the performance as an energy producer was less than

  16. Anaerobic digestion of the organic fraction of municipal solid waste: influence of co-digestion with manure.

    PubMed

    Hartmann, Hinrich; Ahring, Birgitte K

    2005-04-01

    Anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was investigated in two thermophilic (55 degrees C) wet digestion treatment systems R1 and R2. Initially OFMSW was co-digested with manure with a successively higher concentration of OFMSW, at a hydraulic retention time (HRT) of 14-18 d and an organic loading rate (OLR) of 3.3-4.0 g-VS/l/d. Adaptation of the co-digestion process to a OFMSW:manure ratio of 50% (VS/VS) was established over a period of 6 weeks. This co-digestion ratio was maintained in reactor R2 while the ratio of OFMSW to manure was slowly increased to 100% in reactor R1 over a period of 8 weeks. Use of recirculated process liquid to adjust the organic loading to R1 was found to have a beneficial stabilization effect. The pH rose to a value of 8 and the reactor showed stable performance with high biogas yield and low VFA levels. The biogas yield from source-sorted OFMSW was 0.63-0.71 l/g-VS both in the co-digestion configuration and in the treatment of 100% OFMSW with process liquid recirculation. This yield is corresponding to 180-220 m3 biogas per ton OFMSW. VS reduction of 69-74% was achieved when treating 100% OFMSW. None of the processes showed signs of inhibition at the free ammonia concentration of 0.45-0.62 g-N/l. PMID:15878026

  17. Is phytoremediation without biomass valorization sustainable? - comparative LCA of landfilling vs. anaerobic co-digestion.

    PubMed

    Vigil, Miguel; Marey-Pérez, Manuel F; Martinez Huerta, Gemma; Álvarez Cabal, Valeriano

    2015-02-01

    This study examines the sustainability of phytoremediation for soils contaminated with heavy metals, especially the influence of management of the produced metal-enriched biomass on the environmental performance of the complete system. We examine a case study in Asturias (north of Spain), where the land was polluted with Pb by diffuse emissions from an adjacent steelmaking factory. A Phytoremediation scenario based on this case was assessed by performing a comparative life cycle assessment and by applying the multi-impact assessment method ReCiPe. Our Baseline scenario used the produced biomass as feedstock for an anaerobic digester that produces biogas, which is later upgraded cryogenically. The Baseline scenario was compared with two alternative scenarios: one considers depositing the produced biomass into landfill, and the other considers excavating the contaminated soil, disposing it in a landfill, and refilling the site with pristine soil. A sensitivity analysis was performed using different yields of biomass and biogas, and using different distances between site and biomass valorization/disposal center. Our results show that the impacts caused during agricultural activities and biomass valorization were compensated by the production of synthetic natural gas and the avoided impact of natural gas production. In addition, it was found that if the produced biomass was not valorized, the sustainability of phytoremediation is questionable. The distance between the site and the biomass processing center is not a major factor for determining the technology's sustainability, providing distances are less than 200-300 km. However, distance to landfill or to the source of pristine soil is a key factor when deciding to use phytoremediation or other ex-situ conventional remediation techniques. PMID:25461087

  18. EVALUATION OF THE FULL-SCALE APPLICATION OF ANAEROBIC SLUDGE DIGESTION AT THE BLUE PLAINS WASTEWATER TREATMENT FACILITY, WASHINGTON, DC

    EPA Science Inventory

    The mesophilic-thermophilic digestion process is a new two-step concept for treating municipal wasterwater sludges. The first step operates under mesophilic process conditions (digestion with anaerobic microorganisms that thrive at 90 to 100F). The second step operates under ther...

  19. New generic mathematical model for WWTP sludge digesters operating under aerobic and anaerobic conditions: Model building and experimental verification

    Microsoft Academic Search

    M. de Gracia; P. Grau; E. Huete; J. Gómez; J. L. García-Heras; E. Ayesa

    2009-01-01

    This paper presents a new mathematical model developed to reproduce the performance of a generic sludge digester working either under aerobic or anaerobic operational conditions. The digester has been modelled as two completely mixed tanks associated with gaseous and liquid volumes. The conversion model has been developed based on a plant wide modelling methodology (PWM) and comprises biochemical transformations, physicochemical

  20. Biological nutrients removal from the supernatant originating from the anaerobic digestion of the organic fraction of municipal solid waste.

    PubMed

    Malamis, S; Katsou, E; Di Fabio, S; Bolzonella, D; Fatone, F

    2014-09-01

    This study critically evaluates the biological processes and techniques applied to remove nitrogen and phosphorus from the anaerobic supernatant produced from the treatment of the organic fraction of municipal solid waste (OFMSW) and from its co-digestion with other biodegradable organic waste (BOW) streams. The wide application of anaerobic digestion for the treatment of several organic waste streams results in the production of high quantities of anaerobic effluents. Such effluents are characterized by high nutrient content, because organic and particulate nitrogen and phosphorus are hydrolyzed in the anaerobic digestion process. Consequently, adequate post-treatment is required in order to comply with the existing land application and discharge legislation in the European Union countries. This may include physicochemical and biological processes, with the latter being more advantageous due to their lower cost. Nitrogen removal is accomplished through the conventional nitrification/denitrification, nitritation/denitritation and the complete autotrophic nitrogen removal process; the latter is accomplished by nitritation coupled with the anoxic ammonium oxidation process. As anaerobic digestion effluents are characterized by low COD/TKN ratio, conventional denitrification/nitrification is not an attractive option; short-cut nitrogen removal processes are more promising. Both suspended and attached growth processes have been employed to treat the anaerobic supernatant. Specifically, the sequencing batch reactor, the membrane bioreactor, the conventional activated sludge and the moving bed biofilm reactor processes have been investigated. Physicochemical phosphorus removal via struvite precipitation has been extensively examined. Enhanced biological phosphorus removal from the anaerobic supernatant can take place through the sequencing anaerobic/aerobic process. More recently, denitrifying phosphorus removal via nitrite or nitrate has been explored. The removal of phosphorus from the anaerobic supernatant of OFMSW is an interesting research topic that has not yet been explored. At the moment, standardization in the design of facilities that treat anaerobic supernatant produced from the treatment of OFMSW is still under development. To move toward this direction, it is first necessary to assess the performance of alternative treatment options. It study concentrates existing data regarding the characteristics of the anaerobic supernatant produced from the treatment of OFMSW and from their co-digestion with other BOW. This provides data documenting the effect of the anaerobic digestion operating conditions on the supernatant quality and critically evaluates alternative options for the post-treatment of the liquid fraction produced from the anaerobic digestion process. PMID:23808751

  1. Continuously-stirred anaerobic digester to convert organic wastes into biogas: system setup and basic operation.

    PubMed

    Usack, Joseph G; Spirito, Catherine M; Angenent, Largus T

    2012-01-01

    Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation. PMID:22824993

  2. Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation

    PubMed Central

    Usack, Joseph G.; Spirito, Catherine M.; Angenent, Largus T.

    2012-01-01

    Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier 1-3. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications 4,5. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane 6,7. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures 8, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations 9. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation 10. PMID:22824993

  3. Potential use of duckweed based anaerobic digester effluent as a feed source for heterotrophic growth of micro-algae

    NASA Astrophysics Data System (ADS)

    Ahmadi, L.; Dupont, R.

    2013-12-01

    Finding an alternative source of energy for the growing world's demand is a challenging task being considered by many scientists. Various types of renewable energy alternatives are being investigated by researchers around the world. The abundance of duckweed (i.e., Lemna and Wolfia sp.) in wetlands and wastewater lagoons, their rapid growth, and their capacity for nutrient, metal and other contaminant removal from wastewater suggests their potential as an inexpensive source of biomass for biofuel production. Another source of biomass for biofuel and energy production is micro-algae. The large-scale growth of micro-algae can potentially be achieved in a smaller footprint and at a higher rate and lower cost via heterotrophic growth compared to autotrophic growth for specific species that can grow under both conditions. Here we describe two types of research. First, two lab-scale, 5 L anaerobic digesters containing municipal raw wastewater that were set up, maintained and monitored over the course of 6 months using duckweed as the feed source. The pH, salinity, amount of gas production and gas composition were measured on a daily basis. The results from these measurements show that duckweed can be used as a good source of biofuel production in the form of methane gas. The second set of reactors consisted of two 1 L batch fed reactors containing algae (Chlorella vulgaris) grown in the lab environment heterotrophically. The pH and DO were monitored on a daily basis in order to investigate their effect on algae growth. Lipid analysis of the harvested algal biomass was done to investigate the efficiency of harvestable biofuel products. A nutrient solution containing glucose as an energy source was used as the initial feed solution, and the potential substitution of the glucose solution with the organic carbon residue from the duckweed digester effluent was investigated. Methane production, carbon stabilization, and gas composition results from the duckweed fed anaerobic digesters, and the growth and biolipid production of heterotrophic micro-algae fed pure substrate versus residual digester effluent carbon are discussed in detail in this study.

  4. Prediction of thermal hydrolysis pretreatment on anaerobic digestion of waste activated sludge.

    PubMed

    Phothilangka, P; Schoen, M A; Huber, M; Luchetta, P; Winkler, T; Wett, B

    2008-01-01

    Thermal hydrolysis is known for an efficient sludge disintegration capability to enhance biogas potential--but to which extent? Obviously, residual VSS concentration in digested sludge gives not sufficient information to predict additional biogas potential. In this paper, different types of waste activated sludge (WAS) were pre-hydrolysed by a full-scale Thermo-Pressure-Hydrolysis Process (Thermo-Druck-Hydrolyse, TDH) and break-down mechanisms on specific organic compounds were investigated. The IWA Anaerobic Digestion Model No.1 (ADM1) has been used for a systematic analysis of monitoring data gained from experimental work. The TDH process combined with anaerobic digestion can be well described by a modified ADM1 model that includes an X(P)-fraction (inactivated aerobic biomass and their decay products). More rapid and more complete degradation of TDH-treated sludge is represented by calibrated disintegration rate and disintegration factors, while biokinetic parameters of acetogenesis and methanogenesis show no sensitivity. TDH process impacts mainly biomass and decay products while inerts Xi already contained in the raw wastewater are hardly converted. Final concentration of soluble inerts in digestion effluent has been increased from 2% to 9% of influent COD due to thermal hydrolysis. An increase in biogas generation (ca. +80%) and in ammonia release (ca. +75%) can be explained by complete degradation of cell mass. PMID:18957761

  5. Characterization of sulfur in raw and anaerobically digested municipal wastewater treatment sludges.

    PubMed

    Du, Weiwei; Parker, Wayne

    2013-02-01

    A microwave-enhanced acid digestion method that was integrated with inductively coupled plasma-atomic emission spectrometry was developed and validated for determining total, soluble, and precipitated sulfur in wastewater treatment sludges. The coefficient of variation of this method was less than 4.0%. The recovery of dosed sulfur from sludge samples was between 97.1% and 100.5%. The composition of sulfur in primary and waste-activated sludge (WAS) before and after anaerobic digestion at 35 and 55 degrees C was characterized by employing this developed method. There was not an apparent relationship between the precipitated sulfur and nonsoluble iron concentrations in sludges. Raw WAS had a more consistent organic sulfur fractionation because of its relatively homogeneous composition. The organic-sulfur-containing components (proteins) of WAS had reduced degradability as compared with that in primary sludge during anaerobic digestion. Digestion at 55 degrees C increased solubilization but not ultimate conversion of organic sulfur in sludge. PMID:23472328

  6. Development of a pilot scale anaerobic digester for biogas production from cow manure and whey mix.

    PubMed

    Comino, Elena; Rosso, Maurizio; Riggio, Vincenzo

    2009-11-01

    This paper presents results from anaerobic digestion of cow manure and whey mix. A pilot scale anaerobic digester, 128 l in volume, has been developed, to operate under batch and fed-batch conditions. The versatile and unique characteristics of the instrument allowed testing the methane production directly in the farm. The digester performance was evaluated with two calibration tests, the main for a period of 56 days. The study test was divided into three phases, one for each type of feeding operation (batch, fed-batch, batch). The initial phase of digestion resulted in 57 l-CH(4)/kg-VS, the second phase had a yield of 86.6 l-CH(4)/kg-VS and the third one had a production of 67 l-CH(4)/kg-VS. The total methane yield was equal to 211.4 l-CH(4)/kg-VS. Using the obtained pilot plant results to a real scale diary production cycle, it was possible to evaluate an electricity production equal to 8.86 kwh per 1 t/d. The conducted tests did show that there is a good potential to the use of a cow manure and whey biomass mix for biogas production. PMID:19559606

  7. Initial examination of microwave pretreatment on primary, secondary and mixed sludges before and after anaerobic digestion.

    PubMed

    Eskicioglu, C; Kennedy, K J; Droste, R L

    2008-01-01

    The effects of microwave pretreatment on disintegration and mesophilic digestion of waste activated sludge (WAS), primary sludge (PS), combined (PS + WAS) sequencing batch reactor (SBR) sludge and anaerobically digested biocake were investigated by both household and bench scale industrial types microwaves at temperatures below and above boiling point. Pretreatment variables, temperature, intensity (cooking rate) and sludge concentration had statistically significant effects on solubilization. The microwave pretreatment also increased the bioavailability of sludge components under batch anaerobic digestion and enhanced the dewaterability of pretreated sludges after digestion. However, the level of improvements in solubilization and biodegradation from different waste sludges were different. While the largest improvement in ultimate biodegradation was observed in WAS, microwave irradiation only affected the rate of biodegradation of pretreated PS samples. Similarly, relatively lower solubilization ratios achieved for combined - SBR sludge was attributed to high sludge age of extended aeration SBR unit. It is possible that initial sludge characteristics may influence final pretreatment outcomes so that general statements of performance cannot always be made. PMID:18309206

  8. Effect of microwave hydrolysis on transformation of steroidal hormones during anaerobic digestion of municipal sludge cake.

    PubMed

    Hamid, Hanna; Eskicioglu, Cigdem

    2013-09-15

    Fate and removal of 16 steroidal (estrogenic, androgenic and progestogenic) hormones were studied during advanced anaerobic digestion of sludge cake using microwave (MW) pretreatment. Effect of pretreatment temperature (80, 120, 160 °C), operating temperature (mesophilic at 35 ± 2 °C, thermophilic at 55 ± 2 °C) and sludge retention time (SRT: 20, 10, 5 days) were studied employing eight lab-scale semi-continuously fed digesters. To determine the potential effect of MW hydrolysis, hormones were quantified in total (sorbed + soluble) and supernatant (soluble) phases of the digester influent and effluent streams. Seven of 16 hormones were above the method reporting limit (RL) in one or more of the samples. Hormone concentrations in total phase of un-pretreated (control) and pretreated digester feeds ranged in <157-2491 ng/L and <157-749 ng/L, respectively. The three studied factors were found to be statistically significant (95% confidence level) in removal of one or more hormones from soluble and/or total phase. MW hydrolysis of the influent resulted in both release (from sludge matrix) and attenuation of hormones in the soluble phase. Accumulation of estrone (E1) as well as progesterone (Pr) and androstenedione (Ad) in most of the digesters indicated possible microbial transformations among the hormones. Compared to controls, all pretreated digesters had lower total hormone concentrations in their influent streams. At 20 days SRT, highest total removal (E1+E2+Ad +Pr) was observed for the thermophilic control digester (56%), followed by pretreated mesophilic digesters at 120 °C and 160 °C with around 48% efficiency. In terms of conventional performance parameters, relative (to control) improvements of MW pretreated digesters at a 5-d SRT ranged in 98-163% and 57-121%, for volatile solids removal and methane production, respectively. PMID:23866136

  9. SHORT COMMUNICATION Gas-Phase Separations of Protease Digests

    E-print Network

    Clemmer, David E.

    SHORT COMMUNICATION Gas-Phase Separations of Protease Digests Stephen J. Valentine, Anne E University, Bloomington, Indiana, USA A mixture of peptides from a complete tryptic digest of ubiquitin has and identify peptides from a tryptic digest of ubiquitin. The mixture was electrosprayed into the gas phase

  10. Comparison of premixing methods for solid-state anaerobic digestion of corn stover.

    PubMed

    Zhu, Jiying; Yang, Liangcheng; Li, Yebo

    2014-10-25

    The development of solid-state anaerobic digestion (SS-AD) has prompted studies to resolve practical challenges such as mixing of feedstock and inoculum. This study compared the performance of SS-AD using three premixing methods. Results showed that at feedstock to inoculum (F/I) ratios of 4 and 6, the two-layer partial premixing method obtained the highest methane yield, followed by one-layer partial premixing and complete premixing methods. Partial premixing methods also showed wider daily methane yield peaks than the complete premixing method. The volatile fatty acid (VFA) concentration was affected by the premixing method, and was highly correlated to methane yield; while the concentration of remaining holocellulose was correlated to pH and alkalinity. SS-AD digesters failed at an F/I ratio of 8, regardless of the premixing method. Adding extra inoculum to the top of failed digesters resulted in recovery of methane production. PMID:25459852

  11. Effect of fillers on key characteristics of sludge thermophilic anaerobic digestion.

    PubMed

    Shao, Liming; Xu, Yuanshun; Wang, Tianfeng; Lü, Fan; He, Pinjing

    2015-10-01

    In anaerobic digestion (AD) of sludge, AD efficiency and digested sludge (DS) dewaterability are critical factors. In this study, polyester non-woven fabric fillers were integrated into a sludge digester. The effect of such fillers on digestion was investigated in thermophilic temperature range in semi-continuous mode. Methane production of filler system and control reactor were significantly different (P<0.05, paired t-test). At hydraulic retention times of 18days and 12days, the corresponding methane yields from filler system were 140% and 161%, respectively, of the yields from control digester without filler. Improvement of DS dewaterability was uncertain during 110days of operation. While after a longer period of digestion, filler system resulted in a lower normalized capillary suction time of DS (76.5±21.6sL/g total suspended solids) than control reactor (118.7±32.9sL/g total suspended solids). The results showed that the filler could improve thermophilic AD performance, except at too short hydraulic retention times. PMID:26151853

  12. Wastewater reclamation and methane production using water hyacinth and anaerobic digestion

    SciTech Connect

    Chynoweth, D.P.; Dolenc, D.A.; Schwegler, B.; Reddy, K.R.

    1983-01-01

    Research reported here supports the conclusion that water hyacinth ponds are effective in the secondary treatment of domestic wastewater and under these conditions exhibited an average growth yield of 60 dry tons/ha-yr. However, treatment efficiencies and growth yields vary significantly in response to factors which include: (1) of nutrients in the pond influent; (2) residence times and water depth; (3) cultural techniques such as plant density and harvest frequency; (4) environmental conditions such as temperature, frost, etc.; and (5) insect infestation. These variables are under more intense study using smaller scale experiments. The results of these studies will be employed to determine optimum conditions for operation of the larger ponds. Work thus far completed on the anaerobic digestion of hyacinth and sludge has provided information on feed properties, feed biodegradabilities, digestion efficiencies under conventional digestion, nutritional balance, and the effects of blend constituents on methane yield and production rate. It is known that these feeds can be digested without external nutrient addition or pH control. The kinetics and efficiencies are comparable to those of other biomass or waste feeds; in fact, the yield from primary sludge is the highest we have seen reported for particulate feeds. Two conventional digester designs are currently exhibiting a significant increase in feed conversion to methane. Future laboratory research will continue to focus on advanced digestion and pretreatment for improvement of conversion efficiencies and net energy production. This will be complemented by operation of a larger scale experimental test unit.

  13. Digestion of frozen/thawed food waste in the hybrid anaerobic solid-liquid system

    SciTech Connect

    Stabnikova, O. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)], E-mail: costab@ntu.edu.sg; Liu, X.Y.; Wang, J.Y. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2008-07-01

    The hybrid anaerobic solid-liquid (HASL) system, which is a modified two-phase anaerobic digester, is to be used in an industrial scale operation to minimize disposal of food waste at incineration plants in Singapore. The aim of the present research was to evaluate freezing/thawing of food waste as a pre-treatment for its anaerobic digestion in the HASL system. The hydrolytic and fermentation processes in the acidogenic reactor were enhanced when food waste was frozen for 24 h at -20 deg. C and then thawed for 12 h at 25 deg. C (experiment) in comparison with fresh food waste (control). The highest dissolved COD concentrations in the leachate from the acidogenic reactors were 16.9 g/l on day 3 in the control and 18.9 g/l on day 1 in the experiment. The highest VFA concentrations in the leachate from the acidogenic reactors were 11.7 g/l on day 3 in the control and 17.0 g/l on day 1 in the experiment. The same volume of methane was produced during 12 days in the control and 7 days in the experiment. It gave the opportunity to diminish operational time of batch process by 42%. The effect of freezing/thawing of food waste as pre-treatment for its anaerobic digestion in the HASL system was comparable with that of thermal pre-treatment of food waste at 150 deg. C for 1 h. However, estimation of energy required either to heat the suspended food waste to 150 deg. C or to freeze the same quantity of food waste to -20 deg. C showed that freezing pre-treatment consumes about 3 times less energy than thermal pre-treatment.

  14. Evaluation and characterization during the anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor.

    PubMed

    Xiao, Xiaolan; Huang, Zhenxing; Ruan, Wenquan; Yan, Lintao; Miao, Hengfeng; Ren, Hongyan; Zhao, Mingxing

    2015-10-01

    The anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor (AnMBR) was investigated at two different operational modes, including no sludge discharge and daily sludge discharge of 20L. The AnMBR provided excellent and reliable permeate quality with high COD removal efficiencies over 99%. The obvious accumulations of long chain fatty acids (LCFAs) and Ca(2+) were found in the anaerobic digester by precipitation and agglomeration. Though the physicochemical process contributed to attenuating the free LCFAs toxicity on anaerobic digestion, the digestion efficiency was partly influenced for the low bioavailability of those precipitates. Moreover, higher organic loading rate (OLR) of 5.8kg COD/(m(3)d) and digestion efficiency of 78% were achieved as the AnMBR was stably operated with sludge discharge, where the membrane fouling propensity was also alleviated, indicating the crucial significance of SRT control on the treatment of high-strength kitchen waste slurry via AnMBRs. PMID:26141283

  15. Anaerobic co-digestion of pig manure and crude glycerol at mesophilic conditions: biogas and digestate.

    PubMed

    Astals, S; Nolla-Ardèvol, V; Mata-Alvarez, J

    2012-04-01

    Crude glycerol derived from biodiesel production is characterized by its high concentration of organic carbon and its solubility in water; properties that make it a suitable co-substrate to improve the efficiency of a manure digester. An increase of about 400% in biogas production was obtained under mesophilic conditions when pig manure was co-digested with 4% of glycerol, on a wet-basis, compared to mono-digestion. The increase in biogas production was mainly a consequence of the increase in organic loading rate. However, the differences could also be related to the synergy between both substrates and the carbon-to-nitrogen ratio. Moreover, the analysis of the macro-compounds, protein, lipids, carbohydrates and fibers, showed lower removal efficiencies in the co-digester as the microorganisms obtained nutrients from the soluble carbohydrates provided by the glycerol. The digestate stability, evaluated through a respirometric assay, showed that co-substrate addition does not exert a negative impact on digestate quality. PMID:22341889

  16. Sulfate reduction, nutrient limitation, and reactor design considerations in anaerobic digesters

    SciTech Connect

    Clancy, P.B.

    1991-01-01

    Three areas of improvement in anaerobic digestion were investigated: inhibition of sulfate reduction, nutrient limitation, and reactor design. In the anaerobic treatment of wastewaters containing high concentrations of sulfate, hydrogen sulfide, an undesirable end product, is produced by sulfate reducing bacteria (SRB). Research was conducted to evaluate the feasibility of adding SRB-specific biochemical inhibitors to a waste stream as a method of preventing sulfate reduction in continuous anaerobic digesters. Two classes of inhibitory compounds were identified: (1) sulfate analogs and (2) transition metal divalent cations. Molybdate was found to have an immediate inhibitory effect on sulfate reduction, and a delayed effect on other trophic groups. Non-specific inhibition was not caused by a dynamic imbalance due to cessation of fatty acid degradation via sulfate reduction. Transition metals had no effect on sulfate reduction or overall digester performance in high sulfate digesters. The hypothesis that nutrient limitation could be synergistically coupled with the addition of SRB-specific inhibitors was investigated. Recovery of sulfate reduction was slower after molybdate removal from the feed when phosphate was limited as compared with when it was continually added, although this effect may have been an indirect result of non-specific inhibition. Periodic pulse nutrient addition was investigated as a method of (1) reducing cell growth, sludge production and related disposal costs and (2) reducing nutrient addition costs. Sustained waste treatment performance was demonstrated for iron, phosphorus, and nitrogen-free feeds. When withheld nutrients were added in pulses, effective operation could be maintained over long periods. Increasing pulse strength delayed the onset of adverse effects related to nutrient starvation.

  17. Effect of sulfate on low-temperature anaerobic digestion.

    PubMed

    Madden, Pádhraig; Al-Raei, Abdul M; Enright, Anne M; Chinalia, Fabio A; de Beer, Dirk; O'Flaherty, Vincent; Collins, Gavin

    2014-01-01

    The effect of sulfate addition on the stability of, and microbial community behavior in, low-temperature anaerobic expanded granular sludge bed-based bioreactors was investigated at 15°C. Efficient bioreactor performance was observed, with chemical oxygen demand (COD) removal efficiencies of >90%, and a mean SO(2-) 4 removal rate of 98.3%. In situ methanogensis appeared unaffected at a COD: SO(2-) 4 influent ratio of 8:1, and subsequently of 3:1, and was impacted marginally only when the COD: SO(2-) 4 ratio was 1:2. Specific methanogenic activity assays indicated a complex set of interactions between sulfate-reducing bacteria (SRB), methanogens and homoacetogenic bacteria. SO(2-) 4 addition resulted in predominantly acetoclastic, rather than hydrogenotrophic, methanogenesis until >600 days of SO(2-) 4-influenced bioreactor operation. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes. Fluorescence in situ hybridizations (FISH), qPCR and microsensor analysis were combined to investigate the distribution of microbial groups, and particularly SRB and methanogens, along the structure of granular biofilms. qPCR data indicated that sulfidogenic genes were present in methanogenic and sulfidogenic biofilms, indicating the potential for sulfate reduction even in bioreactors not exposed to SO(2-) 4. Although the architecture of methanogenic and sulfidogenic granules was similar, indicating the presence of SRB even in methanogenic systems, FISH with rRNA targets found that the SRB were more abundant in the sulfidogenic biofilms. Methanosaeta species were the predominant, keystone members of the archaeal community, with the complete absence of the Methanosarcina species in the experimental bioreactor by trial conclusion. Microsensor data suggested the ordered distribution of sulfate reduction and sulfide accumulation, even in methanogenic granules. PMID:25120534

  18. Effect of sulfate on low-temperature anaerobic digestion

    PubMed Central

    Madden, Pádhraig; Al-Raei, Abdul M.; Enright, Anne M.; Chinalia, Fabio A.; de Beer, Dirk; O'Flaherty, Vincent; Collins, Gavin

    2014-01-01

    The effect of sulfate addition on the stability of, and microbial community behavior in, low-temperature anaerobic expanded granular sludge bed-based bioreactors was investigated at 15°C. Efficient bioreactor performance was observed, with chemical oxygen demand (COD) removal efficiencies of >90%, and a mean SO2?4 removal rate of 98.3%. In situ methanogensis appeared unaffected at a COD: SO2?4 influent ratio of 8:1, and subsequently of 3:1, and was impacted marginally only when the COD: SO2?4 ratio was 1:2. Specific methanogenic activity assays indicated a complex set of interactions between sulfate-reducing bacteria (SRB), methanogens and homoacetogenic bacteria. SO2?4 addition resulted in predominantly acetoclastic, rather than hydrogenotrophic, methanogenesis until >600 days of SO2?4-influenced bioreactor operation. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes. Fluorescence in situ hybridizations (FISH), qPCR and microsensor analysis were combined to investigate the distribution of microbial groups, and particularly SRB and methanogens, along the structure of granular biofilms. qPCR data indicated that sulfidogenic genes were present in methanogenic and sulfidogenic biofilms, indicating the potential for sulfate reduction even in bioreactors not exposed to SO2?4. Although the architecture of methanogenic and sulfidogenic granules was similar, indicating the presence of SRB even in methanogenic systems, FISH with rRNA targets found that the SRB were more abundant in the sulfidogenic biofilms. Methanosaeta species were the predominant, keystone members of the archaeal community, with the complete absence of the Methanosarcina species in the experimental bioreactor by trial conclusion. Microsensor data suggested the ordered distribution of sulfate reduction and sulfide accumulation, even in methanogenic granules. PMID:25120534

  19. High-solids anaerobic digestion: comparison of three pilot scales.

    PubMed

    Guendouz, J; Buffière, P; Cacho, J; Carrère, M; Delgenes, J-P

    2008-01-01

    Two experiments were undertaken in three different experimental set-ups in order to compare them: an industrial 21-m3 pilot reactor, a new 40-l laboratory pilot reactor and bmp type plasma bottles. Three consecutive batch dry digestion tests of municipal solid waste were performed under mesophilic conditions with the same feedstock in all vessels. Biogas and methane production at the end of the tests were similar (around 200 m3 CH4STP/tVS) for both pilot reactors and were different from the bottle tests. The dynamics of methane production and VFA accumulation concurred. However, the maximal levels of VFA transitory accumulation varied between reactors and between runs in a same reactor. Ammonia levels were similar in both reactors. These results show that the new reactor accurately imitates the conditions found in the larger one. Adaptation of microorganisms to the waste and operating conditions was also pointed out along the consecutive batches. Thermophilic semi-continuous tests were performed in both reactors with similar conditions. The methane production efficiencies were similar. PMID:19029716

  20. Anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing.

    PubMed

    Siles, J A; Martín, M A; Chica, A F; Martín, A

    2010-08-01

    The anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing, in which COD was found to be 1054 and 428 g/L, respectively, was studied in batch laboratory-scale reactors at mesophilic temperature (35 degrees C). Glycerol was acidified with H(3)PO(4) in order to recover the alkaline catalyst employed in the transesterification reaction (KOH) as agricultural fertiliser (potassium phosphates). Wastewater was subjected to an electrocoagulation process in order to reduce its oil content. After mixing, the anaerobic revalorisation of the wastewater was studied employing inoculum-substrate ratios ranging from 5.02 to 1.48 g VSS/g COD and organic loading rates of 0.27-0.36 g COD/g VSS d. Biodegradability was found to be around 100%, while the methane yield coefficient was 310 mL CH(4)/g COD removed (1 atm, 25 degrees C). At the equilibrium time, the proportionality between r' and the load was constant, showing 1.55 mL CH(4)/(g VSS g COD h). The results showed that anaerobic co-digestion reduces the clean water and nutrient requirement, with the consequent economical and environmental benefit. PMID:20363620

  1. Characterization of a Methanogenic Community within an Algal Fed Anaerobic Digester

    PubMed Central

    Ellis, Joshua T.; Tramp, Cody; Sims, Ronald C.; Miller, Charles D.

    2012-01-01

    The microbial diversity and metabolic potential of a methanogenic consortium residing in a 3785-liter anaerobic digester, fed with wastewater algae, was analyzed using 454 pyrosequencing technology. DNA was extracted from anaerobic sludge material and used in metagenomic analysis through PCR amplification of the methyl-coenzyme M reductase ? subunit (mcrA) gene using primer sets ML, MCR, and ME. The majority of annotated mcrA sequences were assigned taxonomically to the genera Methanosaeta in the order Methanosarcinales. Methanogens from the genus Methanosaeta are obligate acetotrophs, suggesting this genus plays a dominant role in methane production from the analyzed fermentation sample. Numerous analyzed sequences within the algae fed anaerobic digester were unclassified and could not be assigned taxonomically. Relative amplicon frequencies were determined for each primer set to determine the utility of each in pyrosequencing. Primer sets ML and MCR performed better quantitatively (representing the large majority of analyzed sequences) than primer set ME. However, each of these primer sets was shown to provide a quantitatively unique community structure, and thus they are of equal importance in mcrA metagenomic analysis. PMID:23724331

  2. Valorisation of biodiesel production wastes: Anaerobic digestion of residual Tetraselmis suecica biomass and co-digestion with glycerol.

    PubMed

    Santos-Ballardo, David U; Font-Segura, Xavier; Ferrer, Antoni Sánchez; Barrena, Raquel; Rossi, Sergio; Valdez-Ortiz, Angel

    2015-03-01

    One of the principal opportunity areas in the development of the microalgal biodiesel industry is the energy recovery from the solid microalgal biomass residues to optimise the fuel production. This work reports the cumulative methane yields reached from the anaerobic digestion of the solid microalgal biomass residues using different types of inocula, reporting also the improvement of biogas production using the co-digestion of microalgal biomass with glycerol. Results demonstrate that the solid microalgal biomass residues showed better biogas production using a mesophilic inoculum, reaching almost two-fold higher methane production than under thermophilic conditions. Furthermore, the solid microalgal biomass residues methane production rate showed an increase from 173.78 ± 9.57 to 438.46 ± 40.50?mL of methane per gram of volatile solids, when the co-digestion with glycerol was performed. These results are crucial to improve the energy balance of the biodiesel production from Tetraselmis suecica, as well as proposing an alternative way to treat the wastes derived from the microalgae biodiesel production. PMID:25737140

  3. Winery waste recycling through anaerobic co-digestion with waste activated sludge.

    PubMed

    Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

    2014-11-01

    In this study biogas and high quality digestate were recovered from winery waste (wine lees) through anaerobic co-digestion with waste activated sludge both in mesophilic and thermophilic conditions. The two conditions studied showed similar yields (0.40 m(3)/kgCODfed) but different biological process stability: in fact the mesophilic process was clearly more stable than the thermophilic one in terms of bioprocess parameters. The resulting digestates showed good characteristics for both the tested conditions: heavy metals, dioxins (PCDD/F), and dioxin like bi-phenyls (PCBs) were concentred in the effluent if compared with the influent because of the important reduction of the solid dry matter, but remained at levels acceptable for agricultural reuse. Pathogens in digestate decreased. Best reductions were observed in thermophilic condition, while at 37°C the concentration of Escherichia coli was at concentrations level as high as 1000 UFC/g. Dewatering properties of digestates were evaluated by means of the capillary suction time (CST) and specific resistance to filtration (SRF) tests and it was found that a good dewatering level was achievable only when high doses of polymer (more than 25 g per kg dry solids) were added to sludge. PMID:25151445

  4. Anaerobic co-digestion of aircraft deicing fluid and municipal wastewater sludge.

    PubMed

    Zitomer, D; Ferguson, N; McGrady, K; Schilling, J

    2001-01-01

    At many airports, aircraft deicing fluid and precipitation mix, becoming aircraft deicing runoff having a 5-day biochemical oxygen demand (BOD5) of 10(2) to 10(6) mg/L. Publicly owned treatment works can be used for aerobic biological treatment; however, it may be more economical to use anaerobic digesters to codigest a mixture of aircraft deicing fluid and sludge. The objectives of this investigation were to determine benefits and appropriate propylene glycol aircraft deicing fluid loadings to anaerobic codigesters. Results demonstrate aircraft deicing fluid can be successfully codigested to produce methane; supernatant BOD5 and Kjeldahl nitrogen concentration were not higher in codigesters compared to a conventional digester. Aircraft deicing fluid loadings as high as 1.6 g chemical oxygen demand (COD)/L x d were sustainable in codigesters, whereas system fed only aircraft deicing fluid with nutrients and alkalinity achieved a loading of 0.65 g COD/L x d. The sludge used increased digester alkalinity and provided nitrogen, iron, nickel, cobalt, and biomass required for methanogenesis. The deicer provides organics for increased methane production. PMID:11833757

  5. Anaerobic digestion of municipal solid waste as a treatment prior to landfill.

    PubMed

    Nguyen, P H L; Kuruparan, P; Visvanathan, C

    2007-01-01

    Anaerobic digestion of organic fraction of municipal solid waste was conducted in pilot-scale reactor based on high-solid combined anaerobic digestion process. This study was performed in two runs. In Run 1 and Run 2, pre-stage flushing and micro-aeration were conducted to determine their effect in terms of enhancing hydrolysis and acidification in ambient condition. In Run 2, after pre-stage, the methane phase (methanogenesis) was started-up after pH adjustment and inoculum addition in mesophilic condition. Acidified leachate produced in pre-stage was used for percolation during active methane phase. At the end of methane phase, air flushing was conducted before unloading the digesters. Hydrolysis and acidification yield of 140 g C/kg TS and 180 g VFA/kg TS were achieved, respectively in pre-stage. Micro-aeration exhibited an equivocal result in terms of enhancing hydrolysis/acidification; however it showed a positive effect in methane phase performance and this needed further investigation. Leachate percolation during methane phase showed an enhanced methanization when compared to the reactors without leachate percolation. After 60 days, 260 l CH(4)/kg VS was obtained. Based on the waste methane potential, 75% biogas conversion and 61% VS degradation were achieved. PMID:16480863

  6. Effects of lactone, ketone, and phenolic compounds on methane production and metabolic intermediates during anaerobic digestion.

    PubMed

    Wikandari, Rachma; Sari, Noor Kartika; A'yun, Qurrotul; Millati, Ria; Cahyanto, Muhammad Nur; Niklasson, Claes; Taherzadeh, Mohammad J

    2015-02-01

    Fruit waste is a potential feedstock for biogas production. However, the presence of fruit flavors that have antimicrobial activity is a challenge for biogas production. Lactones, ketones, and phenolic compounds are among the several groups of fruit flavors that are present in many fruits. This work aimed to investigate the effects of two lactones, i.e., ?-hexalactone and ?-decalactone; two ketones, i.e., furaneol and mesifurane; and two phenolic compounds, i.e., quercetin and epicatechin on anaerobic digestion with a focus on methane production, biogas composition, and metabolic intermediates. Anaerobic digestion was performed in a batch glass digester incubated at 55 °C for 30 days. The flavor compounds were added at concentrations of 0.05, 0.5, and 5 g/L. The results show that the addition of ?-decalactone, quercetin, and epicathechin in the range of 0.5-5 g/L reduced the methane production by 50 % (MIC50). Methane content was reduced by 90 % with the addition of 5 g/L of ?-decalactone, quercetin, and epicathechin. Accumulation of acetic acid, together with an increase in carbon dioxide production, was observed. On the contrary, ?-hexalactone, furaneol, and mesifurane increased the methane production by 83-132 % at a concentration of 5 g/L. PMID:25416476

  7. Anaerobic Digestion of Renewable Biomass: Thermophilic Temperature Governs Methanogen Population Dynamics ? †

    PubMed Central

    Krakat, Niclas; Westphal, A.; Schmidt, S.; Scherer, P.

    2010-01-01

    Beet silage and beet juice were digested continuously as representative energy crops in a thermophilic biogas fermentor for more than 7 years. Fluorescence microscopy of 15 samples covering a period of 650 days revealed that a decrease in temperature from 60°C to 55°C converted a morphologically uniform archaeal population (rods) into a population of methanogens exhibiting different cellular morphologies (rods and coccoid cells). A subsequent temperature increase back to 60°C reestablished the uniform morphology of methanogens observed in the previous 60°C period. In order to verify these observations, representative samples were investigated by amplified rRNA gene restriction analysis (ARDRA) and fluorescence in situ hybridization (FISH). Both methods confirmed the temperature-dependent population shift observed by fluorescence microscopy. Moreover, all samples investigated demonstrated that hydrogenotrophic Methanobacteriales dominated in the fermentor, as 29 of 34 identified operational taxonomic units (OTUs) were assigned to this order. This apparent discrimination of acetoclastic methanogens contradicts common models for anaerobic digestion processes, such as anaerobic digestion model 1 (ADM1), which describes the acetotrophic Euryarchaeota as predominant organisms. PMID:20097828

  8. Biochar Produced from Anaerobically Digested Fiber Reduces Phosphorus in Dairy Lagoons

    SciTech Connect

    Streubel, Jason D.; Collins, Harold P.; Tarara, Julie M.; Cochran, Rebecca L.

    2012-07-01

    This study evaluated the use of biochar produced from anaerobic digester dairy fiber (ADF) to sequester phosphorus (P) from dairy lagoons. The ADF was collected from a plugged flow digester, air-dried to <8% water content, and pelletized. Biochar was produced by slow pyrolysis in a barrel retort. The potential of biochar to reduce P in the anaerobic digester effluent (ADE) was assessed in small-scale filter systems through which the effluent was circulated. Biochar sequestered an average of 381 mg L?1 P from the ADE, and 4 g L?1 ADF was captured as a coating on the biochar. There was an increase of total (1.9 g kg?1), Olsen (763 mg kg?1), and water-extractable P (914 mg kg?1) bound to the biochar after 15 d of filtration. This accounted for a recovery of 32% of the P in the ADE. The recovered P on the biochar was analyzed using 31P nuclear magnetic resonance for P speciation, which confirmed the recovery of inorganic orthophosphate after liquid extraction of the biochar and the presence of inextractable Ca-P in the solid state. The inorganic phosphate was sequestered on the biochar through physical and weak chemical bonding. Results indicate that biochar could be a beneficial component to P reduction in the dairy system.

  9. An integrated approach to energy recovery from biomass and waste: Anaerobic digestion-gasification-water treatment.

    PubMed

    Milani, M; Montorsi, L; Stefani, M

    2014-06-19

    The article investigates the performance of an integrated system for the energy recovery from biomass and waste based on anaerobic digestion, gasification and water treatment. In the proposed system, the organic fraction of waste of the digestible biomass is fed into an anaerobic digester, while a part of the combustible fraction of the municipal solid waste is gasified. Thus, the obtained biogas and syngas are used as a fuel for running a cogeneration system based on an internal combustion engine to produce electric and thermal power. The waste water produced by the integrated plant is recovered by means of both forward and inverse osmosis. The different processes, as well as the main components of the system, are modelled by means of a lumped and distributed parameter approach and the main outputs of the integrated plant such as the electric and thermal power and the amount of purified water are calculated. Finally, the implementation of the proposed system is evaluated for urban areas with a different number of inhabitants and the relating performance is estimated in terms of the main outputs of the system. PMID:24946772

  10. Energy recovery from the effluent of plants anaerobically digesting urban solid waste

    NASA Astrophysics Data System (ADS)

    1983-03-01

    The parameters of concentration, time, temperature, and pH to find optimum conditions for enzymatically converting unreacted cellulose in the effluent of an anaerobic digester to glucose for ultimate conversion to methane, and then to project the economics to a 100 tons per day plant was studied. The amount of cellulose hydrolysis for enzyme concentrations from 5 to 1000 CIU/gram of substrate using either filter paper or anaerobically digested municipal solid waste (MSW) reacted over periods of time of from 0 to 72 hours is illustrated. The feasibility of recycling enzymes by ultrafilter capture was studied and it is shown that the recovered enzyme is not denatured by any of several possible enzyme loss mechanisms chemical, physical, or biological. Although rather stable enzyme substrate complexes seem to be formed, various techniques permit a 55% enzyme recovery. Posttreatment of digested MSW by cellulase enzymes produces nearly a threefold increase in biomethanation. The value of the additional methane produced in the process is not sufficient to support the cost of enzymes.

  11. Comparison of Seven Chemical Pretreatments of Corn Straw for Improving Methane Yield by Anaerobic Digestion

    PubMed Central

    Song, Zilin; GaiheYang; Liu, Xiaofeng; Yan, Zhiying; Yuan, Yuexiang; Liao, Yinzhang

    2014-01-01

    Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS ?1 in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost. PMID:24695485

  12. Discovery and characterization of a new bacterial candidate division by an anaerobic sludge digester metagenomic approach

    PubMed Central

    Guermazi, Sonda; Daegelen, Patrick; Dauga, Catherine; Rivière, Delphine; Bouchez, Théodore; Godon, Jean Jacques; Gyapay, Gábor; Sghir, Abdelghani; Pelletier, Eric; Weissenbach, Jean; Le Paslier, Denis

    2008-01-01

    We have constructed a large fosmid library from a mesophilic anaerobic digester and explored its 16S rDNA diversity using a high-density filter DNA–DNA hybridization procedure. We identified a group of 16S rDNA sequences forming a new bacterial lineage named WWE3 (Waste Water of Evry 3). Only one sequence from the public databases shares a sequence identity above 80% with the WWE3 group which hence cannot be affiliated to any known or candidate prokaryotic division. Despite representing a non-negligible fraction (5% of the 16S rDNA sequences) of the bacterial population of this digester, the WWE3 bacteria could not have been retrieved using the conventional 16S rDNA amplification procedure due to their unusual 16S rDNA gene sequence. WWE3 bacteria were detected by polymerase chain reaction (PCR) in various environments (anaerobic digesters, swine lagoon slurries and freshwater biofilms) using newly designed specific PCR primer sets. Fluorescence in situ hybridization (FISH) analysis of sludge samples showed that WWE3 microorganisms are oval-shaped and located deep inside sludge flocs. Detailed phylogenetic analysis showed that WWE3 bacteria form a distinct monophyletic group deeply branching apart from all known bacterial divisions. A new bacterial candidate division status is proposed for this group. PMID:18459975

  13. Methane from an integrated hyacinth treatment anaerobic digestion facility

    SciTech Connect

    Hayes, T.D.; Chynoweth, D.P.; Reddy, K.R.; Schwegler, B.

    1985-08-01

    Results to date indicate that the Hyacinth Project could lead to the production of cost-competitive methane from a hyacinth wastewater treatment system. An information base from the project will be available by the end of 1985 to support a decision on whether methane generation from a hyacinth facility is sufficiently attractive for communities and gas companies to pursue at a commercial scale. If the economics are promising, construction of a full-scale plant could begin in the late 1980s. The project could ultimately provide a low-cost supplemental source of pipeline-quality gas while offering a cost-effective wastewater treatment alternative. 9 references, 4 figures, 2 tables.

  14. Continuous determination of volatile products in anaerobic fermenters by on-line capillary gas chromatography.

    PubMed

    Diamantis, V; Melidis, P; Aivasidis, A

    2006-07-28

    Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer. PMID:17723523

  15. Treatment of olive oil mill wastewater by combined process electro-Fenton reaction and anaerobic digestion.

    PubMed

    Khoufi, Sonia; Aloui, Fathi; Sayadi, Sami

    2006-06-01

    In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton process removed 65.8% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100% to 66.9%, which resulted in improving the performance of the anaerobic digestion. A continuous lab-scale methanogenic reactor was operated at a loading rate of 10 g chemical oxygen demand (COD)l(-1) d(-1) without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipid content was achieved by the two successive stages. This result opens promising perspectives since its conception as a fast and cheap pre-treatment prior to conventional anaerobic post-treatment. The use of electro-coagulation as post-treatment technology completely detoxified the anaerobic effluent and removed its toxic compounds. PMID:16678883

  16. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

    PubMed Central

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L?1 day?1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus.

  17. Application of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process.

    PubMed

    Morel, E; Santamaria, K; Perrier, M; Guiot, S R; Tartakovsky, B

    2004-01-01

    This work examined the use of multi-wavelength fluorometry for on-line monitoring of an anaerobic digestion process. Experiments were carried out in a laboratory-scale anaerobic digestor fed with either synthetic or agricultural (cheese factory) wastewater. An in-line fiber optic probe installed in the external recirculation loop of the reactor was used to acquire fluorescence spectra with an interval of 5-10 min. The spectra were compared with analytical measurements taken at the same time to develop regression models, which were then used to predict concentrations of chemical oxygen demand, volatile fatty acids, and other key process parameters. A comparison of partial least squares (PLS), nonlinear principal components regression, and step-wise regression models on an independent set of data showed that the PLS model gave the best prediction accuracy. PMID:15276745

  18. Evaluation of the anaerobic co-digestion of sewage sludge and tomato waste at mesophilic temperature.

    PubMed

    Belhadj, Siham; Joute, Yassine; El Bari, Hassan; Serrano, Antonio; Gil, Aida; Siles, José A; Chica, Arturo F; Martín, M Angeles

    2014-04-01

    Sewage sludge is a hazardous waste, which must be managed adequately. Mesophilic anaerobic digestion is a widely employed treatment for sewage sludge involving several disadvantages such as low methane yield, poor biodegradability, and nutrient imbalance. Tomato waste was proposed as an easily biodegradable co-substrate to increase the viability of the process in a centralized system. The mixture proportion of sewage sludge and tomato waste evaluated was 95:5 (wet weight), respectively. The stability was maintained within correct parameters in an organic loading rate from 0.4 to 2.2 kg total volatile solids (VS)/m(3) day. Moreover, the methane yield coefficient was 159 l/kg VS (0 °C, 1 atm), and the studied mixture showed a high anaerobic biodegradability of 95 % (in VS). Although the ammonia concentration increased until 1,864 ± 23 mg/l, no inhibition phenomenon was determined in the stability variables, methane yield, or kinetics parameters studied. PMID:24682875

  19. Temporal variation in methanogen communities of four different full-scale anaerobic digesters treating food waste-recycling wastewater.

    PubMed

    Lee, Joonyeob; Hwang, Byungchul; Koo, Taewoan; Shin, Seung Gu; Kim, Woong; Hwang, Seokhwan

    2014-09-01

    Methanogen communities were investigated using 454 pyrosequencing in four different full-scale anaerobic digesters treating food waste-recycling wastewater. Seasonal samples were collected for 2 years, and 24 samples were available for microbial analysis from a plug flow thermophilic (PT) digester, a continuously-stirred tank thermophilic (CT) digester, an upflow anerobic sludge blanket mesophilic (UM) digester, and a continuously-stirred tank mesophilic (CM) digester. Methanoculleus, Methanobacterium, Methanothermobacter, and Methanosaeta were revealed to be key methanogens in full-scale anaerobic digestion process treating food waste-recycling wastewater. In the PT digester, Methanoculleus was dominant (96.8%). In the CT digester, Methanoculleus was dominant (95.4%) during the first year of operation, but the dominant genus was shifted to Methanothermobacter (98.5%) due to pH increase. In the UM digester, Methanosaeta was dominant (87.2%). In the CM digester, Methanoculleus was constantly dominant (74.8%) except during CM5 when Methanosaeta was dominant (62.6%) due to the low residual acetate concentration (0.1 g/L). PMID:24767792

  20. Anaerobic co-digestion of forage radish and dairy manure in complete mix digesters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Farmers are increasingly using forage radish as a winter cover crop to achieve multiple soil and environmental benefits. In this study, pilot-scale mixed digesters were used to quantify methane (CH4) and hydrogen sulfide (H2S) production when using forage radish, a sulfur-rich cover crop, as a co-d...

  1. Energy recovery from grass using two-phase anaerobic digestion.

    PubMed

    Yu, H W; Samani, Z; Hanson, A; Smith, G

    2002-01-01

    Municipal solid wastes are major sources of air, water and soil contamination. There is a need for alternative waste management techniques to better utilize the waste and minimize its adverse environmental impact. A two-phase pilot-scale bio-fermentation system was used to evaluate the feasibility of producing methane from grass waste, a major constituent of solid wastes. The bi-phasic system consists of a solid phase and a methane phase. Leachate is re-circulated through the solid phase until a desired level of volatile fatty acid (VFA) is accumulated in the leachate. The leachate is then transferred to the methane reactor where the VFA is converted to methane. The results showed that 67% of the volatile solids in the waste can be converted into soluble chemical oxygen demand in a period of six months. The system produced an average of 0.15 m3 of methane per kg of grass. The average methane concentration in the produced gas was 71%. A mathematical model was developed to estimate the methane and carbon dioxide concentrations in the gas phase as a function of reactor properties. PMID:11942700

  2. Waste activated sludge treatment based on temperature staged and biologically phased anaerobic digestion system.

    PubMed

    Yu, Jingwen; Zheng, Mingxia; Tao, Tao; Zuo, Jiane; Wang, Kaijun

    2013-10-01

    The concept of temperature staged and biological phased (TSBP) was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature (35 to 70 degrees C) as well as the hydraulic retention time (HRT) (2, 4 and 6 days) on the acidogenic phase. The results showed that the solubilization degree of waste-activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70 degrees C, while the acidification degree was highest at 45 degrees C (17.6%), and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree (24.6%) and acidification degree (20.1%) at 45 degrees C. The TSBP system combined the acidogenic reactor (45 degrees C, 4 days) with the methanogenic reactor (35 degrees C, 16 days) and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35 degrees C. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45 degrees C was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system. PMID:24494492

  3. Effects of lipid concentration on anaerobic co-digestion of municipal biomass wastes

    SciTech Connect

    Sun, Yifei, E-mail: sunif@buaa.edu.cn [School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Wang, Dian; Yan, Jiao [School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Qiao, Wei [College of Chemical Science and Engineering, China University of Petroleum, Beijing 102249 (China); Wang, Wei [School of Environment, Tsinghua University, Beijing 100084 (China); Zhu, Tianle [School of Chemistry and Environment, Beihang University, Beijing 100191 (China)

    2014-06-01

    Highlights: • Lipid in municipal biomass would not inhibited the anaerobic digestion process. • A lipid concentration of 65% of total VS was the inhibition concentration. • The amount of Brevibacterium decreased with the increasing of the lipid contents. • Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process. - Abstract: The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2–0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion.

  4. Evaluation of Anammox and denitrification during anaerobic digestion of poultry manure

    Microsoft Academic Search

    Xiao Dong; Ernest W Tollner

    2003-01-01

    Two approaches based on new process development and biological nitrogen transformation were investigated in a bench study for removing nitrogen as N2 gas from poultry waste while stabilizing the wastes. The process, known as “Anammox”, was explored in batch anaerobic culture using serum bottles. The Anammox process involves the use of nitrite as an electron acceptor in the bacterially mediated

  5. The variability in nutrient composition of Anaerobic Digestate granules produced from high shear granulation.

    PubMed

    Mangwandi, Chirangano; JiangTao, Liu; Albadarin, Ahmad B; Allen, Stephen J; Walker, Gavin M

    2013-01-01

    This study investigates the production of organic fertilizer using Anaerobic Digestate (as a nutrient source) and limestone powder as the raw materials. A two-level factorial experimental design was used to determine the influence of process variables on the nutrient homogeneity within the granules. Increasing the liquid-to-solid ratio during granulation resulted in increased granule nutrient homogeneity. Increasing the processing time and the impeller speed were also found to increase the nutrient homogeneity. In terms of nutrients release into deionized water, the granules effectively released both potassium and phosphate into solution. PMID:23083974

  6. Biological degradation of VCCs and CFCs under simulated anaerobic landfill conditions in laboratory test digesters

    Microsoft Academic Search

    Anna Deipser; Rainer Stegmann

    1997-01-01

    The biological degradation of volatile halogenated hydrocarbons (chlorocarbons (VCCs) and chlorofluorocarbons (CFCs)) was\\u000a investigated under simulated conditions of landfills in laboratory test digesters. Fully halogenated VCCs (tetrachloroethylene,\\u000a 1,1,1-trichloroethane, tetrachloromethane and dichloromethane) and CFCs (trichlorofluoromethane (R11), dichlorodifluoromethane\\u000a (R12) and 1,1,2-trichlorotrifluoroethane (R113)) were degraded under anaerobic conditions in addition to the methanogenic\\u000a bacteria in municipal solid waste (MSW) and organic wastes. These

  7. Effects of various pretreatments for enhanced anaerobic digestion with waste activated sludge.

    PubMed

    Kim, Jeongsik; Park, Chulhwan; Kim, Tak-Hyun; Lee, Myunggu; Kim, Sangyong; Kim, Seung-Wook; Lee, Jinwon

    2003-01-01

    The purpose of this study was to enhance the efficiency of anaerobic digestion with waste activated sludge (WAS) by batch experiments. We studied the effects of various pretreatment methods (thermal, chemical, ultrasonic and thermochemical pretreatments) on the biogas production and pollutants reduction owing to solubilization enhancement, particle size reduction, increased soluble protein, and increased soluble COD. The thermochemical pretreatment gave the best results, i.e., the production of methane increased by more than 34.3% and soluble COD (SCOD) removal also increased by more than 67.8% over the control. In this case, the biogas production, methane production and the SCOD removal efficiency were about 5037 l biogas/m3 WAS, 3367 l methane/m3 WAS and 61.4%, respectively. Therefore, it is recognized that higher digestion efficiencies of the WAS were obtained through thermochemical pretreatment of the sludge. PMID:16233404

  8. Effect of urea addition on giant reed ensilage and subsequent methane production by anaerobic digestion.

    PubMed

    Liu, Shan; Ge, Xumeng; Liew, Lo Niee; Liu, Zhe; Li, Yebo

    2015-09-01

    The effect of urea addition on giant reed ensilage and sequential anaerobic digestion (AD) of the ensiled giant reed was evaluated. The dry matter loss during ensilage (up to 90days) with or without urea addition was about 1%. Addition of 2% urea enhanced production of lactic acid by about 4 times, and reduced production of propionic acid by 2-8 times. Besides, urea addition reduced degradation of cellulose and hemicellulose, and increased degradation of lignin in giant reed during ensilage. Ensilage with or without urea addition had no significant effects on the enzymatic digestibility of giant reed, but ensilage with urea addition achieved a cumulative methane yield of 173L/kgVS, which was 18% higher than that of fresh giant reed. The improved methane yield of giant reed could be attributed to the production of organic acids and ethanol during ensilage. PMID:26094194

  9. Case study: the characteristics of the biodegradable waste for the anaerobic digestion plant in Lisbon area.

    PubMed

    Vaz, F; Torres, A; Correia, C Neiva

    2008-01-01

    Taking into account the physical-chemical characteristics of the SC-OFMSW processed at Valorsul's anaerobic digestion plant, the influence of seasonal effects was studied. The waste presents a good quality, with a putrescible content of around 90%. In terms of chemical characteristics, the waste composition is similar to the one referred in the literature. The results show that seasonal variations seem not to affect the SC-OFMSW characteristics. The waste is very soluble and for that reason the solids content in the digester is low (TS in the digestor is 2.8%). The production of biogas is higher than the one predicted in the design operational parameters. Consequently, smaller quantities of compost are produced. PMID:19001708

  10. Improving methane production and phosphorus release in anaerobic digestion of particulate saline sludge from a brackish aquaculture recirculation system.

    PubMed

    Zhang, Xuedong; Ferreira, Rui B; Hu, Jianmei; Spanjers, Henri; van Lier, Jules B

    2014-06-01

    In this study, batch tests were conducted to examine the effects of trehalose and glycine betaine as well as potassium on the specific methanogenic activity (SMA), acid and alkaline phosphatase activity of anaerobic biomass and phosphorus release in anaerobic digestion of saline sludge from a brackish recirculation aquaculture system. The results of ANOVA and Tukey's HSD (honestly significant difference) tests showed that glycine betaine and trehalose enhanced SMA of anaerobic biomass and reactive phosphorus release from the particulate waste. Moreover, SMA tests revealed that methanogenic sludge, which was long-term acclimatized to a salinity level of 17 g/L was severely affected by the increase in salinity to values exceeding 35 g/L. Addition of compatible solutes, such as glycine betaine and trehalose, could be used to enhance the specific methane production rate and phosphorus release in anaerobic digestion from particulate organic waste produced in marine or brackish aquaculture recirculation systems. PMID:24785791

  11. Modeling of Anaerobic Digestion with a Focus on Estimation of Hydrolysis Constants at 35, 55, and 60 °C.

    PubMed

    Haghighatafshar, Salar; Ossiansson, Elin; Koch, Konrad; Kjerstadius, Hamse; Jansen, Jes la Cour; Davidsson, Åsa

    2015-07-01

    Hydrolysis constants of mixed sludge at 35, 55, and 60 °C were found to be 0.32, 0.44, and 0.50 1/d, respectively, in pilot-scale, semicontinuously operated anaerobic digesters. The hydrolysis constants and estimated chemical oxygen demand fractions in the feed were introduced to a mathematical model for anaerobic digestion published by Siegrist et al. (2002), which is similar to Anaerobic Digestion Model No. 1. First-order and Monod-type kinetics were tested for estimation of hydrolysis constants. The applied kinetics were found to affect the outcome of the regression study. Moreover, the free ammonia inhibition model was excluded for both propionate oxidation and acetate conversion, thanks to the apparent acclimatized biomass. No substantial accumulation of volatile fatty acids was observed in the reactors at 35, 55, and 60 °C, corresponding to free ammonia nitrogen concentrations of about 20, 110, and 130 g N/m(3), respectively. PMID:26163494

  12. Effect of different pH-values on process parameters in two-phase anaerobic digestion of high-solid substrates.

    PubMed

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2015-01-01

    In many publications, primary fermentation is described as a limiting step in the anaerobic digestion of fibre-rich biomass [Eastman JA, Ferguson JF. Solubilization of particulacte carbon during the anaerobic digeston. J WPCF. 1981;53:352-366; Noike T, Endo G, Chang J, Yaguchi J, Matsumoto J. Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion. Biotechnol Bioeng. 1985;27:1482-1489; Arntz HJ, Stoppok E, Buchholz K. Anaerobic hydroysis of beet pulp-discontiniuous experiments. Biotechnol Lett. 1985;7:113-118]. The microorganisms of the primary fermentation process differ widely from the methanogenic microorganisms [Pohland FG, Ghosh S. Developments in anaerobic stabilization of organic wastes-the two-phase concept. Environ Lett. 1971;1:255-266]. To optimize the biogas process, a separation in two phases is suggested by many authors [Fox P, Pohland GK. Anaerobic treatment applications and fundamentals: substrate specificity during phase separation. Water Environ Res. 1994;66:716-724; Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580]. To carry out the examination, a two-phase laboratory-scale biogas plant was established, with a physical phase separation. In previous studies, the regulation of the pH-value during the acid formation was usually carried out by the addition of sodium hydroxide [Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580; Ueno Y, Tatara M, Fukui H, Makiuchi T, Goto M, Sode K. Production of hydrogen and methane from organic solid wastes by phase separation of anaerobic process. Bioresour Technol. 2007;98:1861-1865; Zoetemeyer RJ, van den Heuvel JC, Cohen A. pH influence on acidogenic dissimilation of glucose in an anaerobic digestor. Water Res. 1982;16:303-311]. A new technology without the use of additives was developed in which the pH-regulation is executed by the pH-dependent recycling of effluent from the anaerobic filter into the acidification reactor. During this investigation, the influence of the different target pH-values (5.5, 6.0, 7.0 and 7.5) on the degradation rate, the gas composition and the methane yield of the substrate maize silage was determined. With an increase in the target pH-value from 5.5 to 7.5, the acetic acid equivalent decreased by 88.1% and the chemical oxygen demand-concentration by 18.3% in the hydrolysate. In response, there was a 58% increase in the specific methane yield of the overall system. Contrary to earlier studies, a marked increase in biogas production and in substrate degradation was determined with increasing pH-values. However, these led to a successive approximation of a single-phase process. Based on these results, pH-values above 7.0 seem to be favourable for the digestion of fibre-rich substrates. PMID:25413114

  13. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions

    SciTech Connect

    Kim, Dong-Hoon [Wastes Energy Research Center, Korea Institute of Energy Research, 102, Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Oh, Sae-Eun, E-mail: saeun@hanbat.ac.kr [Department of Environmental Engineering, Hanbat National University, San 16-1, Duckmyoung-dong, Yuseong-gu, Daejeon (Korea, Republic of)

    2011-09-15

    Highlights: > High-solids (dry) anaerobic digestion is attracting a lot of attention these days. > One reactor was fed with food waste (FW) and paper waste. > Maximum biogas production rate of 5.0 m{sup 3}/m{sup 3}/d was achieved at HRT 40 d and 40% TS. > The other reactor was fed with FW and livestock waste (LW). > Until a 40% LW content increase, the reactor exhibited a stable performance. - Abstract: With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO{sub 2} emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH{sub 4} production yield (MPY) and VS reduction achieved in this condition were 5.0 m{sup 3}/m{sup 3}/d, 0.25 m{sup 3} CH{sub 4}/g COD{sub added}, and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m{sup 3}/m{sup 3}/d, MPY of 0.26 m{sup 3} CH{sub 4}/g COD{sub added}, and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes.

  14. Can sludge dewatering reactivate microorganisms in mesophilically digested anaerobic sludge? Case of belt filter versus centrifuge.

    PubMed

    Erkan, M; Sanin, F D

    2013-01-01

    The anaerobic digestion process that successfully reduces the organic content of sludge is one of the most common alternatives to meet pathogen reduction requirements for particular classes of biosolids. However, recently it was reported that, much higher densities of indicator bacteria were measured in dewatered cake samples compared to samples collected after anaerobic digestion. Additionally, this increase was commonly observed after centrifugation but not after belt filter dewatering. Several hypotheses were tested to explain this occurrence; however, much of the attention was given to the reactivation of the indicator bacteria which might enter a viable but non-culturable state (VBNC) during digestion. The objective of this research is to examine sludge samples from 5 different full-scale treatment plants in order to observe the effect of dewatering processes on the reactivation potential of indicator bacteria. The bacterial enumerations were performed by both Standard Culturing Methods (SCM) and quantitative polymerase chain (qPCR) on samples collected after digestion and dewatering. Results obtained by SCM indicated that in two investigated treatment plants operating belt filter dewatering, an average 0.6 log decrease was observed after the dewatering process. However, 0.7-1.4 log increases were observed immediately after centrifuge dewatering for the other three treatment plants. On the other hand, qPCR results gave 0.1-1.9 log higher numbers compared to SCM. Comparative evaluation of results obtained by two analytical methods for five treatment plants indicates that the differences observed might be originating from both reactivation of VBNC bacteria and amplification of DNA from dead cells found in the sludge. PMID:23141737

  15. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions.

    PubMed

    Kim, Dong-Hoon; Oh, Sae-Eun

    2011-01-01

    With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO(2) emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH(4) production yield (MPY) and VS reduction achieved in this condition were 5.0m(3)/m(3)/d, 0.25 m(3) CH(4)/g COD(added), and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m(3)/m(3)/d, MPY of 0.26 m(3) CH(4)/g COD(added), and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes. PMID:21684733

  16. Performance of uasb reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste

    Microsoft Academic Search

    H. S Shin; S. K Han; Y. C Song; C. Y Lee

    2001-01-01

    This study was conducted to investigate the performance of the upflow anaerobic sludge blanket (UASB) reactor treating leachate from acidogenic fermenter in the two-phase anaerobic digestion of food waste. The chemical oxygen demand (COD) removal efficiency was consistently over 96% up to the loading rates of 15.8gCOD\\/ld. The methane production rate increased to 5.5l\\/ld. Of all the COD removed, 92%

  17. Modelling the anaerobic digestion of wastewater derived from the pressing of orange peel produced in orange juice manufacturing

    Microsoft Academic Search

    José Ángel Siles López; Arturo Francisco Chica Pérez; Antonio Martín Martín

    2010-01-01

    A kinetic model of the anaerobic digestion of wastewater derived from the pressing of orange peel is proposed. The process was conducted in a laboratory-scale, completely stirred tank reactor operating in batch mode at mesophilic temperature. The anaerobic biodegradability of the physical–chemical pre-treated wastewater was found to be 84%, while methane yield coefficient was 297NmL CH4\\/g COD removed. The mathematical

  18. Enzymatic characterization of acid tolerance response (ATR) during the enhanced biohydrogen production process from Taihu cyanobacteria via anaerobic digestion

    Microsoft Academic Search

    Qun Yan; Aijie Wang; Chunfai Yu; Nanqi Ren; Yibo Zhang; Guangsheng Zhang

    2011-01-01

    Enhancement of biohydrogen production via anaerobic digestion from Taihu cyanobacteria (blue algae) after acid stress on anaerobic sludge, and the enzymatic characterization of the acid tolerance response (ATR) during the enhanced biohydrogen production process were investigated in this study. Comparing to those of the control, biohydrogen accumulation and hydrogen content increased by 1.9 and 1.7 times, when 12.5 and 7.5 g\\/L

  19. Anaerobic treatment of residual lemon pulp in digesters with semi-continuous feed.

    PubMed

    Navarro, A R; Lopez, Z; Salguero, J; Maldonado, M C

    2013-01-01

    Lemon growing areas in the north of Argentina have industries that produce concentrated juice, peel and essential oil and generate a significant amount of liquid and solid waste as lemon pulp. In Argentina, despite the potential applications that the pulp has as animal feed and human and industrial raw material, only 10% is used for these purposes and the rest is discarded into the environment causing many ecological and economic problems. There is little information in the literature on biotechnologies for the treatment of this industrial waste. This paper shows that lemon pulp is a suitable substrate to be treated by anaerobic digestion. We obtained 86 and 92% reduction of chemical oxygen demand in a digester with a semi-continuous feed and retention time of 10 and 20 days respectively and a productivity of 0.406 g CH(4)/g VS h. Comparative tests showed that pre-digesting the pulp improved the process of digestion and increased biogas generation by 20%. PMID:23202554

  20. Gas-phase separations of protease digests.

    PubMed

    Valentine, S J; Counterman, A E; Hoaglund, C S; Reilly, J P; Clemmer, D E

    1998-11-01

    A mixture of peptides from a complete tryptic digest of ubiquitin has been analyzed by ion mobility/time-of-flight mass spectrometry techniques. All components of the mixture were electrosprayed and ions were separated in the gas phase based on differences in their mobilities through helium before being dispersed into a time-of-flight mass spectrometer for mass-to-charge analysis. The data show that ions separate into families primarily according to differences in their charge states and, to a lesser extent, differences in conformation. This approach reduces spectral congestion typically associated with electrosprayed mixtures and provides charge assignments for mass-to-charge ratio data. Gas-phase separations of ions appear to provide a new physical basis for characterizing components of biological mixtures. PMID:9794086

  1. Development of an efficient process for the treatment of residual sludge discharged from an anaerobic digester in a sewage treatment plant.

    PubMed

    Abe, Naoki; Tang, Yue-Qin; Iwamura, Makoto; Ohta, Hiroto; Morimura, Shigeru; Kida, Kenji

    2011-09-01

    In order to reduce the discharge of residual sludge from an anaerobic digester, pre-treatment methods including low-pressure wet-oxidation, Fenton oxidation, alkali treatment, ozone oxidation, mechanical destruction and enzymatic treatment were evaluated and compared. VSS removal efficiencies of greater than 50% were achieved in cases of low-pressure wet-oxidation, Fenton oxidation and alkali treatment. Residual sludge from an anaerobic digester was pre-treated and subjected to thermophilic anaerobic digestion. As a result, the process of low-pressure wet-oxidation followed by anaerobic digestion achieved the highest VSS removal efficiency of 83%. The total efficiency of VSS removal of sewage sludge consisting of primary and surplus sludge would be approximately 92%, assuming that the VSS removal efficiency of sewage sludge is 50% in the anaerobic digester of the sewage treatment plant. PMID:21703855

  2. Potential for direct interspecies electron transfer in an electric-anaerobic system to increase methane production from sludge digestion.

    PubMed

    Zhao, Zhiqiang; Zhang, Yaobin; Wang, Liying; Quan, Xie

    2015-01-01

    Direct interspecies electron transfer (DIET) between Geobacter species and Methanosaeta species is an alternative to interspecies hydrogen transfer (IHT) in anaerobic digester, which however has not been established in anaerobic sludge digestion as well as in bioelectrochemical systems yet. In this study, it was found that over 50% of methane production of an electric-anaerobic sludge digester was resulted from unknown pathway. Pyrosequencing analysis revealed that Geobacter species were significantly enriched with electrodes. Fluorescence in situ hybridization (FISH) further confirmed that the dominant Geobacter species enriched belonged to Geobacter metallireducens. Together with Methanosaeta species prevailing in the microbial communities, the direct electron exchange between Geobacter species and Methanosaeta species might be an important reason for the "unknown" increase of methane production. Conductivity of the sludge in this electric-anaerobic digester was about 30% higher than that of the sludge in a control digester without electrodes. This study not only revealed for the first time that DIET might be the important mechanism on the methanogenesis of bioelectrochemical system, but also provided a new method to enhance DIET by means of bioelectric enrichment of Geobacter species. PMID:26057581

  3. Water Environment Research Foundation (WERF) anaerobic digestion and related processes, odour and health effects study.

    PubMed

    Witherspoon, J R; Adams, G; Cain, W; Cometto-Muniz, E; Forbes, B; Hentz, L; Novack, J T; Higgins, M; Murthy, S; McEwen, D; Ong, H T; Daigger, G T

    2004-01-01

    Biosolids odour emissions can affect the ability of wastewater utilities to implement beneficial biosolids processing and reuse programs. Communities often become more sensitised and vocal about biosolids issues, once they experience odours emanating from a nearby site. Odour impacts from biosolids, including potential human health effects, have been targeted recently by many national and local newspapers, citizens' groups, and regulatory agencies, who have raised significant concerns, ranging from viable disposal methods/sites to outright bans. Many national and local regulatory agencies in the United States are considering biosolids disposal bans in their communities because of misinformation, poor science, and citizen pressure, but primarily because of odour impact concerns. The wastewater industry has a relatively poor understanding of the operations and treatment parameters that influence biosolids odour emissions. Thus, wastewater treatment plants are often unable to control the odour quality of the biosolids that are delivered into communities. A research study to demonstrate the influence of anaerobic digestion, mechanical dewatering, and storage design and operating parameters on the odour quality of the final product was performed and is the subject of this paper. Established and new sampling and analytical methods were used to measure biosolids odour emissions from 11 test sites in North America. By determining the impacts of these control variables on biosolids odour quality, design and operations of anaerobic digestion systems might be enhanced. This paper also summarises a corollary study performed as part of the WERF research study that addresses the health effects of biosolids odours. PMID:15484737

  4. Comparison of solid-state to liquid anaerobic digestion of lignocellulosic feedstocks for biogas production.

    PubMed

    Brown, Dan; Shi, Jian; Li, Yebo

    2012-11-01

    Lignocellulosic biomass feedstocks (switchgrass, corn stover, wheat straw, yard waste, leaves, waste paper, maple, and pine) were evaluated for methane production under liquid anaerobic digestion (L-AD) and solid-state anaerobic digestion (SS-AD). No significant difference in methane yield between L-AD and SS-AD, except for waste paper and pine, were found. However, the volumetric productivity was 2- to 7-fold greater in the SS-AD system compared with the L-AD system, except for paper. Methane yields from corn stover, wheat straw, and switchgrass were 2-5 times higher than those from yard waste, maple, and pine biomass. Waste paper had a methane yield of only 15 L/kg VS caused by souring during SS-AD due to organic overloading. Pine also had very low biogas yield of 17 L/kg VS, indicating the need for pretreatment prior to SS-AD. The findings of this study can guide future studies to improve the efficiency and stability of SS-AD of lignocellulosic biomass. PMID:22995169

  5. Performance and stability improvements in anaerobic digestion of thermally hydrolyzed municipal biowaste by a biofilm system.

    PubMed

    Wang, Wei; Hou, Huahua; Hu, Song; Gao, Xingbao

    2010-03-01

    In this present study, thermal hydrolysis pre-treatment improved the hydrolysis of organic solids and the solid-liquid separation ability of MB, making it possible to obtain a long solid retention time (SRT) and high degradation ratio in anaerobic sequencing batch reactor (ASBR). Biofilm carriers were introduced into ASBR to prolong the mean cell retention time (MCRT). The biofilm system operated at an organic loading rate (OLR) of 3.5-5 gVSL(reactor)(-1)day(-1) and a hydraulic retention time (HRT) of 13.3 days. The biofilm carriers provided perfect conditions for microbe retention and growth, improving the digestion efficiency. The MCRT was 89-150 days and SRT was 24-36 days, with the methane yield of 330-370 mL g(-1)VS(added) and VS(d) of 62-70%. Meanwhile, due to the mass-transport resistance and high microbe density of the biofilm, the system show high stability. Therefore, the biofilm system provided an approach for a highly efficient anaerobic digestion of municipal biowaste. PMID:19910188

  6. Utilisation of wastewater nutrients for microalgae growth for anaerobic co-digestion.

    PubMed

    Sahu, Ashish K; Siljudalen, Jon; Trydal, Tina; Rusten, Bjørn

    2013-06-15

    The feasibility of growing microalgae in natural light using wastewater high in nutrients (N & P) for the production of more bioenergy was examined. The main retrofitting unit would be a photobioreactor for wastewater treatment plants (wwtp) having anaerobic digesters in close proximity. Theoretical microalgae production rates from different wastewater sources (municipal wwtp, source separation of human and animal wastewaters) were estimated using mass balance. Mass and energy balances for a conventional wwtp using chemically enhanced primary treatment was investigated for microalgae growth for a situation limited by availability of carbon dioxide (CO2) generated onsite and where additional CO2 was imported from outside source. Reject water from dewatering of anaerobically digested sludge from four wwtp around Oslo region were pretreated for improved light penetration and examined for microalgae growth. Several pre-treatment methods were investigated. Pretreatment using flocculation + settling + anthracite filtration yielded high light transmittance. A maximum microalgae growth rate of 13 g TSS/m(2)-d was achieved using this pretreated reject water. The challenges of integrating photobioreactors with existing units have been highlighted. PMID:23570973

  7. Effects of lipid concentration on anaerobic co-digestion of municipal biomass wastes.

    PubMed

    Sun, Yifei; Wang, Dian; Yan, Jiao; Qiao, Wei; Wang, Wei; Zhu, Tianle

    2014-06-01

    The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2-0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion. PMID:24075452

  8. Impact of ozone assisted ultrasonication pre-treatment on anaerobic digestibility of sewage sludge.

    PubMed

    Tian, Xinbo; Trzcinski, Antoine Prandota; Lin, Li Leonard; Ng, Wun Jern

    2015-07-01

    Impact of ultrasonication (ULS) and ultrasonication-ozonation (ULS-Ozone) pre-treatment on the anaerobic digestibility of sewage sludge was investigated with semi-continuous anaerobic reactors at solid retention time (SRT) of 10 and 20days. The control, ULS and ULS-Ozone reactors produced 256, 309 and 348mL biogas/g CODfed and the volatile solid (VS) removals were 35.6%, 38.3% and 42.1%, respectively at SRT of 10days. At SRT of 20days, the biogas yields reached 313, 337 and 393mL biogas/g CODfed and the VS removal rates were 37.3%, 40.9% and 45.3% in the control, ULS and ULS-Ozone reactors, respectively. ULS-Ozone pre-treatment increased the residual organic amount in the digested sludge. These soluble residual organics were found to contain macromolecules with molecular weights (MW) larger than 500kDa and smaller polymeric products with MW around 19.4 and 7.7kDa. These compounds were further characterized to be humic acid-like substances with fluorescent spectroscopy analysis. PMID:26141875

  9. Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite.

    PubMed

    Angelidaki, I; Petersen, S P; Ahring, B K

    1990-07-01

    The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaptation of the digestors, very rapid degradation of oil was observed and more than 80% of the oil was degraded within a few hours after daily feeding. In batch experiments, glyceride trioleate was found to be inhibitory to thermophilic anaerobic digestion when the concentrations were higher than 2.0 g/l. However, addition of bentonite (a clay mineral) at concentrations of 0.15% and 0.45% was found to partly overcome this inhibition. Addition of calcium chloride in concentration of 3 mM (0.033% w/v) showed a similar positive effect on the utilization of oil, but the effect was lower than with bentonite. PMID:1366749

  10. Ammonia-methane two-stage anaerobic digestion of dehydrated waste-activated sludge.

    PubMed

    Nakashimada, Yutaka; Ohshima, Yasutaka; Minami, Hisao; Yabu, Hironori; Namba, Yuzaburo; Nishio, Naomichi

    2008-07-01

    The study investigated methane production from dehydrated waste-activated sludge (DWAS) with approximately 80% water content under thermophilic conditions. The repeated batch-wise treatment of DWAS using methanogenic sludge unacclimated to high concentrations of ammonia, increased the ammonia production up to 7,600 mg N per kilogram total wet sludge of total ammonia concentration, and stopped the methane production. Investigation revealed that the loading ratio of DWAS for methanogenic sludge influences anaerobic digestion. Methane production significantly decreased and ammonia concentration increased with the increase in loading ratio of DWAS. Since the semicontinuous culture revealed that approximately 50% of organic nitrogen in DWAS converted to ammonia at sludge retention time (SRT) after 4 days at 37 degrees C and 1.33 days at 55 degrees C, the previous stripping of the ammonia produced from DWAS was carried out. The stripping of ammonia increased methane production significantly. This ammonia-methane two-stage anaerobic digestion demonstrated a successful methane production at SRT 20 days in the semicontinuous operation using a laboratory-scale reactor system. PMID:18491038

  11. Maximum organic loading rate for the single-stage wet anaerobic digestion of food waste.

    PubMed

    Nagao, Norio; Tajima, Nobuyuki; Kawai, Minako; Niwa, Chiaki; Kurosawa, Norio; Matsuyama, Tatsushi; Yusoff, Fatimah Md; Toda, Tatsuki

    2012-08-01

    Anaerobic digestion of food waste was conducted at high OLR from 3.7 to 12.9 kg-VS m(-3) day(-1) for 225 days. Periods without organic loading were arranged between the each loading period. Stable operation at an OLR of 9.2 kg-VS (15.0 kg-COD) m(-3) day(-1) was achieved with a high VS reduction (91.8%) and high methane yield (455 mL g-VS-1). The cell density increased in the periods without organic loading, and reached to 10.9×10(10) cells mL(-1) on day 187, which was around 15 times higher than that of the seed sludge. There was a significant correlation between OLR and saturated TSS in the sludge (y=17.3e(0.1679×), r(2)=0.996, P<0.05). A theoretical maximum OLR of 10.5 kg-VS (17.0 kg-COD) m(-3) day(-1) was obtained for mesophilic single-stage wet anaerobic digestion that is able to maintain a stable operation with high methane yield and VS reduction. PMID:22705526

  12. Biochar enables anaerobic digestion of aqueous phase from intermediate pyrolysis of biomass.

    PubMed

    Torri, Cristian; Fabbri, Daniele

    2014-11-01

    Intermediate pyrolysis produces a two-phase liquid whose aqueous phase is characterized by low heating value and high water content (aqueous pyrolysis liquid, APL). Anaerobic digestion can be the straightest way to produce a fuel (methane) from this material. Batch tests showed poor performance in anaerobic digestion of APL, which underlined the inhibition of biological process. Nutrient supplementation was ineffective, whereas biochar addition increased yield of methane (60±15% of theoretical) with respect to pure APL (34±6% of theoretical) and improved the reaction rate. On the basis of batch results, a semi-continuous biomethanation test was set up, by adding an increasingly amount of APL in a 30ml reactor preloaded with biochar (0.8gml(-1)). With a daily input of 5gd(-1)l(-1) of APL (corresponding to overall amount of 0.1kgl(-1) added before the end of the study) the yield of methane was 65±5% of the theoretical. PMID:25277261

  13. Enhancement of Taihu blue algae anaerobic digestion efficiency by natural storage.

    PubMed

    Miao, Hengfeng; Lu, Minfeng; Zhao, Mingxing; Huang, Zhenxing; Ren, Hongyan; Yan, Qun; Ruan, Wenquan

    2013-12-01

    Taihu blue algae after different storage time from 0 to 60 d were anaerobic fermented to evaluate their digestibility and process stability. Results showed that anaerobic digestion (AD) of blue algae under 15 d natural storage led to the highest CH4 production of 287.6 mL g(-1) VS at inoculum substrate ratio 2.0, demonstrating 36.69% improvement comparing with that from fresh algae. Storage of blue algae led to cell death, microcystins (MCs) release and VS reduction by spontaneous fermentation. However, it also played an important role in removing algal cell wall barrier, pre-hydrolysis and pre-acidification, leading to the improvement in CH4 yield. Closer examination of volatile fatty acids (VFA) variation, VS removal rates and key enzymes change during AD proved short storage time (? 15 d) of blue algae had higher efficiencies in biodegradation and methanation. Furthermore, AD presented significant biodegradation potential for MCs released from Taihu blue algae. PMID:24128398

  14. Coupling of the hydrogen and polyhydroxyalkanoates (PHA) production through anaerobic digestion from Taihu blue algae.

    PubMed

    Yan, Qun; Zhao, Minxing; Miao, Hengfeng; Ruan, Wenquan; Song, Rentao

    2010-06-01

    Coupling bio-production of hydrogen and polyhydroxyalkanoates (PHA) from Taihu blue algae through metabolites circulation was investigated. It was found that the pH adjustment, especially basification was more practical and efficient than other methods for the pretreatment of blue algae before anaerobic digestion. On this occasion, SCOD, biogas accumulation and hydrogen content reached 26 mg/gTS, 500 mL and 37.2%, and which were 4.3, 1.3 and 14.4 times of those of the control group, respectively. Secondly, amounts of both butyric acid and hydrogen could be further increased when blue algae was alkali pretreated at pH 13, as the accumulation of butyric acid, acetic acid and hydrogen reached 1.7, 1.4 and 3.8 times compared to those of the control, respectively. Finally, the coupling bio-production of hydrogen and PHA was conducted through pumping organic residues into PHA fermenter from anaerobic digester. Remarkably, it was found that the larger the pumping rate of carbon and nitrogen sources supply, the higher the yield of DCW and PHA could be expected by Bacillus cereus. PMID:20153165

  15. Kinetic parameters estimation in an anaerobic digestion process using successive quadratic programming.

    PubMed

    Aceves-Lara, C A; Aguilar-Garnica, E; Alcaraz-González, V; González-Reynoso, O; Steyer, J P; Dominguez-Beltran, J L; González-Alvarez, V

    2005-01-01

    In this work, an optimization method is implemented in an anaerobic digestion model to estimate its kinetic parameters and yield coefficients. This method combines the use of advanced state estimation schemes and powerful nonlinear programming techniques to yield fast and accurate estimates of the aforementioned parameters. In this method, we first implement an asymptotic observer to provide estimates of the non-measured variables (such as biomass concentration) and good guesses for the initial conditions of the parameter estimation algorithm. These results are then used by the successive quadratic programming (SQP) technique to calculate the kinetic parameters and yield coefficients of the anaerobic digestion process. The model, provided with the estimated parameters, is tested with experimental data from a pilot-scale fixed bed reactor treating raw industrial wine distillery wastewater. It is shown that SQP reaches a fast and accurate estimation of the kinetic parameters despite highly noise corrupted experimental data and time varying inputs variables. A statistical analysis is also performed to validate the combined estimation method. Finally, a comparison between the proposed method and the traditional Marquardt technique shows that both yield similar results; however, the calculation time of the traditional technique is considerable higher than that of the proposed method. PMID:16180459

  16. Effects of different SRT on anaerobic digestion of MSW dosed with various MSWI ashes.

    PubMed

    Lo, H M; Chiu, H Y; Lo, S W; Lo, F C

    2012-12-01

    This study investigated different solid retention time (SRT) on municipal solid waste (MSW) anaerobic digestion with various MSW incinerator fly ash (FA) and bottom ash (BA) addition. Results showed that biogas production rates (BPRs, ? 200 to ? 400 mL/gVS) with organic loading rate of ? 0.053 gVS/gVS(reactor) (Day 1-435, SRT 20 days, SRT20) at FA 1g/d (FA1), BA 12 g/d (BA12) and BA 24 g/d (BA24) dosed bioreactors increased after adaptation. BPRs with SRT10 and SRT5 decreased while BPRs with SRT40 showed to increase compared to initial BPRs (? 200 mL/gVS) with SRT20. SRT5 operation reduced the BPRs (? 10 - ? 90 mL/gVS) significantly and only BA12 and BA24 dosed bioreactors could recover the BPRs (? 100 - ? 200 mL/gVS) after SRT20 operation (Day 613-617) compared to FA1 and FA3 and control. Released levels of Co, Mo and W at BA12 and BA24 dosed bioreactors showed most potential to improve MSW anaerobic digestion. PMID:23026339

  17. Anaerobic digestion and co-digestion of slaughterhouse waste (SHW): influence of heat and pressure pre-treatment in biogas yield.

    PubMed

    Cuetos, M J; Gómez, X; Otero, M; Morán, A

    2010-10-01

    Mesophilic anaerobic digestion (34+/-1 degrees C) of pre-treated (for 20 min at 133 degrees C, >3 bar) slaughterhouse waste and its co-digestion with the organic fraction of municipal solid waste (OFMSW) have been assessed. Semi-continuously-fed digesters worked with a hydraulic retention time (HRT) of 36 d and organic loading rates (OLR) of 1.2 and 2.6 kg VS(feed)/m(3)d for digestion and co-digestion, respectively, with a previous acclimatization period in all cases. It was not possible to carry out an efficient treatment of hygienized waste, even less so when OFMSW was added as co-substrate. These digesters presented volatile fatty acids (VFA), long chain fatty acids (LCFA) and fats accumulation, leading to instability and inhibition of the degradation process. The aim of applying a heat and pressure pre-treatment to promote splitting of complex lipids and nitrogen-rich waste into simpler and more biodegradable constituents and to enhance biogas production was not successful. These results indicate that the temperature and the high pressure of the pre-treatment applied favoured the formation of compounds that are refractory to anaerobic digestion. The pre-treated slaughterhouse wastes and the final products of these systems were analyzed by FTIR and TGA. These tools verified the existence of complex nitrogen-containing polymers in the final effluents, confirming the formation of refractory compounds during pre-treatment. PMID:20176467

  18. Microbial trophic interactions and mcrA gene expression in monitoring of anaerobic digesters.

    PubMed

    Alvarado, Alejandra; Montañez-Hernández, Lilia E; Palacio-Molina, Sandra L; Oropeza-Navarro, Ricardo; Luévanos-Escareño, Miriam P; Balagurusamy, Nagamani

    2014-01-01

    Anaerobic digestion (AD) is a biological process where different trophic groups of microorganisms break down biodegradable organic materials in the absence of oxygen. A wide range of AD technologies is being used to convert livestock manure, municipal and industrial wastewaters, and solid organic wastes into biogas. AD gains importance not only because of its relevance in waste treatment but also because of the recovery of carbon in the form of methane, which is a renewable energy and is used to generate electricity and heat. Despite the advances on the engineering and design of new bioreactors for AD, the microbiology component always poses challenges. Microbiology of AD processes is complicated as the efficiency of the process depends on the interactions of various trophic groups involved. Due to the complex interdependence of microbial activities for the functionality of the anaerobic bioreactors, the genetic expression of mcrA, which encodes a key enzyme in methane formation, is proposed as a parameter to monitor the process performance in real time. This review evaluates the current knowledge on microbial groups, their interactions, and their relationship to the performance of anaerobic biodigesters with a focus on using mcrA gene expression as a tool to monitor the process. PMID:25429286

  19. Conductive heating and microwave hydrolysis under identical heating profiles for advanced anaerobic digestion of municipal sludge.

    PubMed

    Mehdizadeh, Seyedeh Neda; Eskicioglu, Cigdem; Bobowski, Jake; Johnson, Thomas

    2013-09-15

    Microwave (2.45 GHz, 1200 W) and conventional heating (custom pressure vessel) pretreatments were applied to dewatered municipal waste sludge (18% total solids) using identical heating profiles that span a wide range of temperatures (80-160 °C). Fourteen lab-scale semi-continuous digesters were set up to optimize the energy (methane) output and sludge retention time (SRT) requirements of untreated (control) and thermally pretreated anaerobic digesters operated under mesophilic and thermophilic temperatures. Both pretreatment methods indicated that in the pretreatment range of 80-160 °C, temperature was a statistically significant factor (p-value < 0.05) for increasing solubilization of chemical oxygen demand and biopolymers (proteins, sugars, humic acids) of the waste sludge. However, the type of pretreatment method, i.e. microwave versus conventional heating, had no statistically significant effect (p-value >0.05) on sludge solubilization. With the exception of the control digesters at a 5-d SRT, all control and pretreated digesters achieved steady state at all three SRTs, corresponding to volumetric organic loading rates of 1.74-6.96 g chemical oxygen demand/L/d. At an SRT of 5 d, both mesophilic and thermophilic controls stopped producing biogas after 20 d of operation with total volatile fatty acids concentrations exceeding 1818 mg/L at pH <5.64 for mesophilic and 2853 mg/L at pH <7.02 for thermophilic controls, while the pretreated digesters continued producing biogas. Furthermore, relative (to control) organic removal efficiencies dramatically increased as SRT was shortened from 20 to 10 and then 5 d, indicating that the control digesters were challenged as the organic loading rate was increased. Energy analysis showed that, at an elevated temperature of 160 °C, the amount of methane recovered was not enough to compensate for the energy input. Among the digesters with positive net energy productions, control and pretreated digesters at 80 °C were more favorable at an SRT of 10 d. PMID:23866153

  20. Nutrient removal and biogas upgrading by integrating freshwater algae cultivation with piggery anaerobic digestate liquid treatment.

    PubMed

    Xu, Jie; Zhao, Yongjun; Zhao, Guohua; Zhang, Hui

    2015-08-01

    An integrated approach that combined freshwater microalgae Scenedesmus obliquus (FACHB-31) cultivation with piggery anaerobic digestate liquid treatment was investigated in this study. The characteristics of algal growth, biogas production, and nutrient removal were examined using photobioreactor bags (PBRbs) to cultivate S. obliquus (FACHB-31) in digestate with various digestate dilutions (the concentration levels of 3200, 2200, 1600, 1200, 800, and 400 mg L(-1) chemical oxygen demand (COD)) during 7-day period. The effects of the level of pollutants on nutrient removal efficiency and CO2 removal process were investigated to select the optimum system for effectively upgrade biogas and simultaneously reduce the nutrient content in digestate. The treatment performance displayed that average removal rates of COD, total nitrogen (TN), total phosphorous (TP), and CO2 were 61.58-75.29, 58.39-74.63, 70.09-88.79, and 54.26-73.81 %, respectively. All the strains grew well under any the dilution treatments. With increased initial nutrient concentration to a certain range, the CO4 content (v/v) of raw biogas increased. Differences in the biogas enrichment of S. obliquus (FACHB-31) in all treatments mainly resulted from variations in biomass productivity and CO2 uptake. Notably, the diluted digestate sample of 1600 mg L(-1) COD provided an optimal nutrient concentration for S. obliquus (FACHB-31) cultivation, where the advantageous nutrient and CO2 removals, as well as the highest productivities of biomass and biogas upgrading, were revealed. Results showed that microalgal biomass production offered real opportunities to address issues such as CO2 sequestration, wastewater treatment, and biogas production. PMID:25808519