Showing papers on "Biogas published in 2002"
TL;DR: In this paper, a 3.0-l upflow reactor was used to investigate individual effects of hydraulic retention time (HRT), chemical oxygen demand (COD) concentration in wastewater (14- 36 g COD/l), pH (4.5-6.0), and temperature (20-55°C) on bio-hydrogen production from the wastewater.
413 citations
01 Jan 2002
234 citations
ENEA1
TL;DR: In this paper, the authors evaluated the effects of using different bacteria inoculums at identical technical settings on the anaerobic digestion process for the treatment of semi-solid organic waste available from the orthofruit market.
219 citations
TL;DR: In this paper, the authors presented an analysis of a number of selected options available for developing countries in the context of reducing total greenhouse gas emission per unit of useful energy for cooking, assuming that biomass as an energy carrier is CO2-neutral; however, other GHGs emitted from biomass combustion cause a net greenhouse effect; accordingly, in this study only the non-CO2 greenhouse gases are considered in estimating GHG emission for different biomass-based cooking options.
Abstract: Large quantities of biomass fuels are used for cooking in the developing countries. Although biomass is a renewable source of energy, traditional biomass-fired stoves cause significant greenhouse gas (GHG) emissions due to formation of products of incomplete combustion; also, exposure to smoke from these stoves causes serious health problems. This paper presents an analysis of a number of selected options available for developing countries in the context of reducing total greenhouse gas emission per unit of useful energy for cooking. It is assumed that biomass as an energy carrier is CO2—neutral. However, other GHGs emitted from biomass combustion cause a net greenhouse effect; accordingly, in this study only the non-CO2 greenhouse gases i.e. CH4 and N2O are considered in estimating GHG emission for different biomass-based cooking options. The total GHG emission from traditional wood-fired stoves is estimated to be about 110 g of CO2 equivalent per mega joule of useful energy (g CO2-e MJuseful−1) delivered to the cooking pot; this can be compared with 42, 5, 2, 350, 166 and 196 g CO 2 -e MJuseful−1 in case of improved wood-, biogas-, producer gas-, kerosene-, natural gas- and LPG-fired stoves, respectively. Modern biomass based cooking options such as improved biomass-, biogas- and producer gas-fired stoves can potentially play an important role in mitigating GHG emission from domestic cooking by providing an alternative to kerosene-, natural gas- and LPG-fired stoves.
196 citations
TL;DR: Waste management involving bioresource recovery in a cane molasses-based distillery engaged in the manufacture of rectified spirit (alcohol) is described, contributing to the elimination of effluent discharges.
168 citations
TL;DR: 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, and showed that 67% of the volatile solids in the waste can be converted into soluble chemical oxygen demand in a period of six months.
156 citations
TL;DR: 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.
141 citations
TL;DR: 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 and it was found that the gas production rates for pre-treated sludges were higher than those for untreated sludge.
140 citations
Patent•
17 Dec 2002
TL;DR: In this article, the agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon monoxide and hydrogen.
Abstract: The present invention relates to a process and apparatus for processing agricultural waste to make alcohol and/or biodiesel. The agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon monoxide and hydrogen. The syngas is converted to an alcohol which may be stored, sold, used, or fed directly to a reactor for production of biodiesel. The solids effluent from the anaerobic digester can be further utilized as slow release, organic certified fertilizer. Additionally, the wastewater from the process is acceptable for immediate reuse in agricultural operations.
137 citations
TL;DR: The anaerobic treatment of the wastewater from the meat processing industry was studied and optimal efficiency of the proposed three-phase separation system as well as the possibility of applying it to the treatment of industrial effluents is supported.
131 citations
TL;DR: The variation of the methane yield during the start-up period of an anaerobic fluidized bed reactor, with acclimatized sludge, increased with time during biofilm development up to the theoretical steady yield value, reported to be around 0.351 CH4/g CODdeg.
TL;DR: Antibiotics commonly used in the treatment of pigs - amoxicillin trihydrate, oxytetracycline hydrochloride and thiamphenicol were added at different concentrations to aliquots of pig waste slurry plus anaerobic sludge in serum bottles to determine the effect of the antibiotics on theAnaerobic process.
TL;DR: An alternative flow-chart for full treatment of wastewaters rich in organic substrates, ammonia, and sulfate, such as those generated in fish cannery industries is described and it is demonstrated that typical sulfate and nitrogen concentrations inFish cannery wastewater are highly appropriate for application of autotrophic post-denitrification.
TL;DR: Leachate recirculation reduced waste-stabilization time and was effective in enhancing gas production and improving leachate quality, especially in terms of COD.
TL;DR: An approximate 60% enhancement in methane yield was noticed with the co-digestion of industrial confectionery wastes with cow manure in a full-scale farm digester.
Patent•
07 May 2002
TL;DR: In this article, integrated waste treatment and fertilizer and feed supplement production methods to be implemented at organic waste source sites, at remote treatment sites, or partially at the organic source site and at a remote location, whether in small or large scale operations.
Abstract: Integrated waste treatment and fertilizer and feed supplement production methods to be implemented at organic waste source sites, at remote treatment sites, or partially at the organic waste source site and at a remote location, whether in small or large scale operations. The methods are suitable for retrofitting existing organic waste sources and for treating the organic waste generated by a single source or by a plurality of sources. These methods provide: Reduction or elimination of emissions of acrid and greenhouse gases; effluents that meet discharge standards and that can be used in wetland and irrigation projects; organic based, granular, slow release NPK fertilizer of standard composition and size that can be supplemented with micronutrients and soil amendment materials and whose composition can be adjusted to meet demands and needs of specific markets; methane-rich biogas recovery for its subsequent use for heating, for power generation or for catalytic and synthetic processes, and feed supplement including feed supplement for cattle. The methods comprise steps for thoroughly separating suspended and dissolved materials, preventing gas emissions and capturing gases, and minimizing waste disposal. Fertilizer base is produced by mixing waste with at least one of a phosphate precipitating agent, a base, a flocculant, and optionally with an ammonia retaining agent and a densifier, subsequently separating and drying the precipitate. Pathogen-free, odor-free and dust-free fertilizer is obtained by temperature controlled incineration.
TL;DR: Straw was evaluated as a biofilm carrier in the methanogenic stage of the two-stage anaerobic digestion of crop residues and it was found that straw would work very well in the intended application.
TL;DR: In this paper, two anaerobic acidogenic reactors, one mesophilic (37°C) and one thermophilic(55°C), were operated with a synthetic wastewater at a series of organic loading rates (OLRs).
TL;DR: The two-stage anaerobic wastewater pre-treatment was modelled and controlled using a fuzzy logic system and designed to handle very strong fluctuations in the concentration of the substrate and the volumetric loading rate.
Patent•
12 Mar 2002
TL;DR: An improved digester for converting wet carbonaceous biomass materials to biogas comprises a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria as discussed by the authors.
Abstract: An improved digester apparatus for converting wet carbonaceous biomass materials to biogas comprises a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria; means for conveying slurried aqueous biomass from a biomass source to the concentrator component and for removing the biogas from the concentrator component; means for conveying concentrated aqueous biomass from the concentrator component to the pressure swing component and for conveying digested aqueous biomass from the pressure swing component to the concentrator component; means for removing waste solids from the pressure swing component; and a pressure swing pump for controlling the pressure within the pressure swing component in a cycle comprising a sub-atmospheric first pressure phase and a second pressure phase at or above atmospheric pressure. Included in the apparatus is a programmable computer provided with a database relating previously measured biomass-biogas conversion data for biomass materials of varying compositions to values for the first and second pressure phases. The computer operates to continuously monitor the pressure of biogas in the pressure swing component and adjust the cycle of the pressure swing pump to optimize biogas conversion of biomass from the biomass source.
TL;DR: The result showed that the food wastes containing high lipids content was effectively degraded by the high solids co-digestion process and over 85% of lipid was degraded to biogas with 60-65% of methane.
Patent•
12 Apr 2002
TL;DR: In this article, a method and apparatus for efficiently generating biogas from feedstocks composed of 10 to 100 percent biodegradable solids including carbohydrates, starches and/or sugars, for a variety of uses including the creation of electricity.
Abstract: A method and apparatus for efficiently generating biogas from feedstocks composed of 10 to 100 percent biodegradable solids including carbohydrates, starches and/or sugars, for a variety of uses including the creation of electricity. The apparatus includes a thermophilic digester and a mesophilic digester used in series, in communication with a feedstock supply system. The digesters may be established as a stand-alone system or made part of a wastewater treatment facility. By carefully metering the specialized feedstocks into and between the digesters, maximum production of biogas can be achieved. The biogas may then be burned as part of an electricity generating process, or stored for later use.
TL;DR: A 14.7-L, three-chamber anaerobic baffled reactor was used to evaluate the treatment of low-strength synthetic wastewater and assess process reactivation after a prolonged period of inactivity, and biomass was mostly in the bottom of the reactor and had moved from the first to the second chamber.
Abstract: A 14.7-L, three-chamber anaerobic baffled reactor (ABR) was used to evaluate the treatment of low-strength synthetic wastewater (chemical oxygen demand [COD] of 300 to 400 mg/L) and assess process reactivation after a prolonged period of inactivity. The reactor was inoculated with anaerobic seed and start-up was immediate. At 26 degrees C and hydraulic retention times (HRTs) of 24 and 12 hours, COD removal averaged 87.2 and 91.0%, respectively, and biogas yield for methane (CH4) was 0.184 and 0.102 m3 CH4/kg COD removed, respectively. The ABR was reactivated after two years without feeding. Response was prompt and removal averaged 85.3% even during the initial 10-day period. Lowering temperature to 16 degrees C did not impair removal efficiency at HRTs of 24 and 12 hours. However, biogas release decreased by 30% and apparent COD conversion to methane dropped by 24 and 31%, respectively. At the end of the study, biomass was mostly in the bottom of the reactor and had moved from the first to the second chamber, while organic stabilization was occurring essentially in the first two chambers (56.1 and 22.4%, respectively, in terms of COD).
TL;DR: In the paper it is shown how the use of a start-up strategy based on the actual activity of key microbes can be used to ensure proper and fast transfer of mesophilic digesters into thermophilic operation.
TL;DR: Steam pressure disruption treatment rendered lignocellulosic substrates readily accessible to anaerobic digestion bacteria and improved both the kinetics of biogas production and the overall methane yield from MSW.
Abstract: Biomass waste, including municipal solid waste (MSW), contains lignocellulosic-containing fiber components that are not readily available as substrates for anaerobic digestion due to the physical shielding of cellulose imparted by the nondigestible lignin Consequently, a substantial portion of the potentially available carbon is not converted to methane and the incompletely digested residues from anaerobic digestion generally require additional processing prior to their return to the environment We investigated and developed steam pressure disruption as a treatment step to render lignocellulosic-rich biomass more digestible and as a means for increasing methane energy recovery The rapid depressurization after steam heating (240°C, 5 min) of the nondigested residues following a 30-day primary digestion of MSW caused a visible disruption of fibers and release of soluble organic components The disrupted material, after reinoculation, provided a rapid burst in methane production at rates double those observed in the initial digestion This secondary digestion proceeded without a lag phase in gas production, provided ∼40% additional methane yields, and was accompanied by a ∼40% increase in volatile solids reduction The secondary digestate was found to be enriched in lignin and significantly depleted in cellulose and hemi-cellulose components when compared to primary digestate Thus, steam pressure disruption treatment rendered lignocellulosic substrates readily accessible to anaerobic digestion bacteria and improved both the kinetics of biogas production and the overall methane yield from MSW Steam pressure disruption is central to a new anaerobic digestion process approach including sequential digestion stages and integrated energy recovery, to improve process yields, provide cogenerated energy for process needs, and to provide effective reuse and recycling of waste biomass materials © 2002 John Wiley & Sons, Inc Biotechnol Bioeng 77: 121–130, 2002
TL;DR: In this article, an attempt has been made to estimate the potential of using biogas plants, solar cookers and improved cookstove for domestic cooking in India, based on 1991 statistics on the bovine population and ownership pattern.
Patent•
21 Aug 2002
TL;DR: In this article, a process for treating manure using anaerobic digestion includes introducing manure into a mixing vessel containing a digester liquid and agitating and filtering a slurry formed therefrom to remove substantially all water insoluble solids, thereby leaving a liquid containing ammonia and reactive organic materials.
Abstract: A process for treating manure using anaerobic digestion includes introducing manure into a mixing vessel containing a digester liquid and agitating and filtering a slurry formed therefrom to remove substantially all water insoluble solids, thereby leaving a liquid containing ammonia and reactive organic materials. The liquid is then heated and ammonia is removed therefrom to produce a substantially ammonia-free liquid containing reactive organic materials, which is cooled and placed in a digester containing anaerobic bacteria to convert the reactive organic materials in the liquid to biogas and to produce a digester liquid. The biogas is withdrawn and utilized to generate electricity, and a small amount of the digester liquid is withdrawn from the digester and recycled back to the mixing vessel. The water insoluble solids and ammonia removed during the process may be converted to ruminant animal feed and concentrated liquid fertilizer, respectively.
Patent•
23 Oct 2002
TL;DR: The fixed-film anaerobic digestion of flushed livestock manure includes an enclosed digester tank (fixed or flexible roof), internal media for biofilm development, a biogas collection and flare system, various pumps, and hydraulic control systems.
Abstract: An apparatus for the fixed-film anaerobic digestion of flushed livestock manure includes an enclosed digester tank (fixed or flexible roof), internal media for biofilm development, a biogas collection and flare system, various pumps, and hydraulic control systems. The preferred media has substantially vertically-oriented, uninterrupted channels to promote enhanced bacterial attachment and biofilm development. The immobilization of microbial biomass within the reactor as a biofilm allows effective treatment of the wastewater at ambient and higher temperatures, as well as reasonable hydraulic retention times. The composition and concentration of bacterial groups in the biofilm developed on the media in the fixed-film digester result in a significantly enhanced anaerobic degradation process. This novel fixed-film digester design expands the potential application of anaerobic digestion to dilute livestock waste with significant levels of suspended solids. This holistic manure treatment system not only stabilizes the wastewater but also produces energy (biogas), controls odors, reduces pathogens, minimizes environmental impact from waste emissions, and maximizes fertilizer and water recovery for reuse.
TL;DR: The feasibility of operating a solid oxide fuel cell (SOFC) on biogas has been studied over a wide compositional range of Biogas, using a small tubular SOFC system operating at 850 °C.
Abstract: The feasibility of operating a solid oxide fuel cell (SOFC) on biogas has been studied over a wide compositional range of biogas, using a small tubular solid oxide fuel cell system operating at 850 °C. It is possible to run the SOFC on biogas, even at remarkably low levels of methane, at which conventional heat engines would not work. The power output varies with methane content, with maximum power production occurring at 45% methane, corresponding to maximal production of H2 and CO through internal dry reforming. Direct electrocatalytic oxidation of methane does not contribute to the power output of the cell. At higher methane contents methane decomposition becomes significant, leading to increased H2 production, and hence transiently higher power production, and deleterious carbon deposition and thus eventual cell deactivation.
TL;DR: The comparison of the profiles obtained with the 3 substrates shows that, overall, the acidification of the organic matter and the methanisation of the VFA follow zero order reactions, in the operating conditions of this study.