Showing papers on "Biogas published in 1991"
TL;DR: In this article, high solids anaerobic digestion of the mechanically sorted organic fraction of municipal solid waste under mesophilic and thermophilic conditions was reported, and the semi-dry thermophilous process has a gas production rate two to three times the mesophilic process and nearly complete biodegradation.
92 citations
TL;DR: In this article, modified definitions for CST digester retention times and first order kinetic coefficients are presented for converting biogas data to standard conditions, and two novel methods for quantifying mass removals, based on direct measurement of reactor mass losses and on Biogas production, allow rapid determination of mass removal rates and detection of gas leakage.
Abstract: Methods are presented for kinetic analysis of anaerobic biomass reactors. In some cases, assumptions implicit in kinetic analysis techniques developed for conventional dilute digestion modes are not applicable to systems operating at high rates and/or high solids concentrations. As a result, modified definitions are presented for CST digester retention times and first order kinetic coefficients. Procedures are presented for converting biogas data to standard conditions. Two novel methods for quantifying mass removals, based on direct measurement of reactor mass losses and on biogas production, allow rapid determination of mass removal rates and detection of gas leakage. The use of a per unit mass basis for reporting concentrations and kinetics is recommended.
90 citations
TL;DR: Denitrification of sanitary landfill leachate with biogas as a sole carbon source was found to be possible and high concentrations of oxygen in the liquid medium and low oxygen concentrations in the aeration gas inhibited denitrification.
68 citations
TL;DR: In this paper, a survey of 32 woody samples (chiefly willow and poplar species grown in a wood-grass system) showed that significant yields of methane (≥ 0·25 liters g−1 volatile solids added) were obtained from 19 of the samples.
67 citations
Patent•
16 May 1991TL;DR: An anaerobic sequence batch process carried out in a single vessel is described in this paper, where the biological reactions occur under a sequential manner and the vessel is operated on a fill-and-draw basis.
Abstract: An anaerobic sequence batch process carried out in a single vessel. The biological reactions occur under anaerobic conditions and the vessel is operated on a fill-and-draw basis in a sequential manner. When waste is entering the reactor, the vessel is mixed by biogas or liquid recirculation. Waste feeding continues until the reactor is filled to its predetermined full liquid level. The anaerobic reaction proceeds with intermittent or continuous mixing. Mixing is then discontinued, allowing the biomass to settle under quiescent conditions resulting in the formation of a low suspended solids supernatant. After sufficient time in the settling cycle, supernatant is withdrawn from the reactor lowering the reactor contents to the predetermined lower liquid level. Gas or liquid recirculation mixing is then begun again along with waste feeding. Excess biomass is wasted from the reactor on a periodic basis. The capacity of the reactor depends on the number of feeding-clarification-wasting cycles that can be achieved in a day.
59 citations
TL;DR: The immobilizing of VS in an anaerobic filter fermenter is a means of reducing the inhibition of methanogenic bacteria by the residual phenolic compounds present in prefermented OMW.
55 citations
TL;DR: Furfural was converted to several intermediates, including furfuryl alcohol, furoic acid, and acetic acid, before final conversion to methane and carbon dioxide under anaerobic conditions and resulted in 80% of the theoretically expected biogas.
Abstract: Furfural, a byproduct formed during the thermal/chemical pretreatment of hemicellulosic biomass, was degraded to methane and carbon dioxide under anaerobic conditions. The consortium of anaerobic microbes responsible for the degradation was enriched using small continuously stirred tank reactor (CSTR) systems with daily batch feeding of biomass pretreatment liquor and continuous addition of furfural. Although the continuous infusion of furfural was initially inhibitory to the anaerobic CSTR system, adaptation of the consortium occurred rapidly with high rates of furfural addition. Addition rates of 7.35 mg furfural/700-mL reactor/d resulted in biogas productions of 375%, of that produced in control CSTR systems, fed the biomass pretreatment liquor only. The anaerobic CSTR system fed high levels of furfural was stable, with a sludge pH of 7.1 and methane gas composition of 69%, compared to the control CSTR, which had a pH of 7.2 and 77% methane. CSTR systems in which furfural was continuously added resulted in 80% of the theoretically expected biogas. Intermediates in the anaerobic biodegradation of furfural were determined by spike additions in serum-bottle assays using the enriched consortium from the CSTR systems. Furfural was converted to several intermediates, including furfuryl alcohol, furoic acid, and acetic acid, before final conversion to methane and carbon dioxide.
47 citations
TL;DR: Sorghum and sorghum/cellulose mixtures were digested at 55°C at effluent solids contents over 25% total solids (TS) as discussed by the authors.
Abstract: Sorghum and sorghum/cellulose mixtures were digested at 55°C at effluent solids contents over 25% total solids (TS). Sorghum alone as a feedstock led to excess NH 3 accumulation, while a sorghum/alpha-cellulose mix controlled NH 3 at acceptable levels. Trace nutrient supplementation was required for stable digestion. Stable performance at organic loading rates (OLR) of 18 and 24 gVS kg −1 day −1 resulted in steady methane production rates of 5.7 and 7.51 CH 4 kg −1 day −1 , respectively. The efficiency of volatile solids (VS) conversion to biogas was 74.8% and 72.1% at organic loading rates (OLR) of 18 and 24 gVS kg −1 day −1 , respectively.
46 citations
TL;DR: Pistia stratiotes, an aquatic weed, was investigated as a substrate for biogas production in batch digestion and when an inoculum was added to a ‘soured’ digester the performance of the latter improved dramatically.
45 citations
TL;DR: In this paper, a generalized framework for economic analysis of biogas plants by capturing the effect of the capacity in the benefits accruing from Biogas utilization is presented.
41 citations
Journal Article•
TL;DR: In this article, the responses of hydrogen and carbon monoxide during organic and hydraulic overloads of anaerobic digestion of waste-activated sludge were compared to con ventional process indicators.
Abstract: Hydrogen and carbon monoxide ( CO ) are two trace gases related to metabolic activity that can be monitored in anaerobic systems. The responses of these two gases during organic and hydraulic overloads of anaerobic digestion of waste-activated sludge were compared to con ventional process indicators. Results indicate that both gases supply ad ditional information beyond that which current monitoring strategies provide. Hydrogen provides information as to the level of stress being exerted on the C02-reducing methanogenic population, and CO gives insight to the status of the acetate-catabolizing population. These trace gases can be conveniently monitored on-line using a real-time data ac quisition system. They provide information that relates to the metabolic status of some of the key bacterial groups and augment information obtained via conventional process indicators studied, including volatile fatty acid to alkalinity ratio, gas production, and major components (CH4 and C02) concentrations. Res. J. Water Pollut. Control Fed., 63, 129(1991).
TL;DR: In this paper, the canteen and mess wastes (CMW) were used for biogas generation in a 200 l Khadi and Village Industries Commission of India digester and a high gas yield of 0·981 m3 kg−1 volatile solids (VS) with a methane content of 50% was obtained.
TL;DR: In this paper, an online measurement of hydrogen in the biogas of a continuously stirred laboratory scale sewage sludge digester was conducted to determine whether this variable could provide advanced warning of digester failure.
TL;DR: In this paper, the influence of trace elements (Co2+, Ni2+ and Fe3+) in varying concentrations and combination, was studied in 1.5 m3 Khadi & Village Industries Commission (KVIC) digesters for biogas generation from mangopeel.
Abstract: The influence of trace elements (Co2+, Ni2+ and Fe3+) in varying concentrations and combination, was studied in 1.5 m3 Khadi & Village Industries Commission (KVIC) digesters for biogas generation from mangopeel. Addition of these trace metals enhanced the biogas yield and methane content moderately, the maximum being with the iron fed digester. The digesters were always found to be stable without much variation in total volatile fatty acids (VFA), pH, total alkalinity and other parameters. A methane content of 62% and biogas yield of 0.49 m3/kg VS added was obtained with 4000 mg/L FeCl3 supplemented mangopeel fed digester as compared to control having biogas yield of 0.22 m3/kg VS added with a methane content of about 48–50%.
TL;DR: The suitability of a number of different anaerobic digester designs for use in rural regions of Pakistan, has been investigated in this article, where a horizontal biogas plant was comparatively expensive but was suitable for those areas where the water table was high.
TL;DR: The palm oil industry plays a major role in the economic development of the country as discussed by the authors, however, large quantities of waste are generated by the industry and many resources can be reclaimed.
Abstract: Oil palm has been gaining increasing importance as a cash crop in several tropical countries. The palm oil industry plays a major role in the economic development of the country. However, large quantities of waste are generated by the industry. The palm oil wastes could be regarded as by-products and many resources can be reclaimed. Palm oil mill effluent (POME) can be used through anaerobic digestion to generate biogas. The biogas contains up to 70% by weight of methane. The dehydrated POME solids, termed palm oil meals (POM), and palm kernel cake (PKC) contain high levels of nutrients and can be used as animal feeds. The shell and fiber wastes are used extensively as fuel for steam production. The shell and fiber ash can be blended with cement for concrete making.
TL;DR: The use of bio-ethanol conversion to petrochemical derivatives has been carried out on only a small scale by the industry as mentioned in this paper, however, this conversion has been done on only small scale.
Abstract: Brazil has become a great producer of bioethanol using sugarcane as the basic raw material. Fed-batch process and continuous process are used. Biogas generation from vinasse, production of dry yeast, and autolyzed bagasse for animal feed are making the ethanol production less polluting and more profitable. Bagasse surplus has also been converted into electrical energy. Another alternative use for bioethanol is its conversion to petrochemical derivatives. Up to the present, however, this conversion has been carried out on only a small scale by the industry.
TL;DR: In this paper, a simple technique for the fermentation of untreated or partly-treated leafy biomass in a digester of novel design without incurring the normal problems of feeding, floating and scum formation of feed, etc.
Abstract: This paper describes a simple technique for the fermentation of untreated or partly-treated leafy biomass in a digester of novel design without incurring the normal problems of feeding, floating and scum formation of feed, etc. The solid phase fermentation studied consists of a bed of biomass frequently sprinkled with an aqueous bacterial inoculum and recycling the leachate to conserve moisture and improve the bacterial dispersion in the bed. The decomposition of the leaf biomass and water hyacinth substrates used in this study was rapid, taking 45 and 30 days for the production of 250 and 235 l biogas per kg total solids (TS) respectively, for the above mentioned substrates at a daily sprinkled volume of 26 ml cm−2 of bed per day sprinkled at 12 h intervals. Very little volatile fatty acid (VFA) intermediates accumulated in the liquid sprinkled, suggesting acidogenesis to be rate-limiting in this process. From the pattern of VFA and gas produced it is concluded that most of the biogas produced is from the biomass bed, thus making the operation of a separate methanogenic reactor unnecessary.
TL;DR: The results of operating a pilot plant for the anaerobic methanogenic thermophilic digestion of wastes in an industrial slaughterhouse in Israel are described, and a product called ‘Peatrum’, which can be used commercially as a substitute for peat-moss, while the process simultaneously generates energy.
TL;DR: In this paper, the potential yield of biogas from one ton of pulp can be estimated as 131 m 3, which is equivalent to 100 litres of petrol in fuel value.
08 Nov 1991
TL;DR: In this article, the authors present an analysis of MSW biogasification using combined anaerobic filtration and hydroponics, showing that the MSW bio-dieselization of lignocellulosic materials leads to the development of anaerobes.
Abstract: Overview. Community methane systems. Wastewater treatment and biomass production by floating aquatic macrophytes. Wastewater treatment using combined anaerobic filtration and hydroponics. Anaerobic digestion. Microbial hydrolysis of lignocellulosic materials. Biogasification kinetics of biomass/waste blends. Anaerobic digestion development. Utilization of anaerobic digester residue. Systems analysis of MSW biogasification.
Journal Article•
TL;DR: In this article, an innovative high-solids anaerobic digestion/aerobic composting process is proposed for processing a large fraction of the organic matter in MSW, which can be used as a fuel for the production of energy.
Abstract: The organic fraction of the material diverted from landfills has potential to be utilized as a raw material to be recycled, used for the production of compost, converted to energy in waste-to-energy facilities, or used for the production of other end products. Given the uncertainties concerning the future availability, production costs, and market prices for conventional fuels, any potential source of alternate energy and alternative energy technologies deserve serious consideration. Faced with an uncertain energy future, several European countries have already started using biomass and MSW as a source of energy. An innovative high-solids anaerobic digestion/aerobic composting process currently under investigation at the University of California, Davis is as an ideal candidate for processing a large fraction of the organic matter in MSW. The principal advantages of this innovative process which is described and discussed in this paper are: (1) the recovery of biogas that can be used as a fuel for the production of energy, and (2) the production of humus-like material that can be used as a high-quality soil amendment or as boiler fuel. The fact that a liquid waste stream that needs further treatment is not generated in this process is another significant advantage.
TL;DR: A distinct improvement of the settling qualities of digester effluents was obtained during the anaerobic digestion process, and gas production was significantly higher at 23 days than at 16 days retention time.
TL;DR: In this paper, a two-stage no-mix anaerobic digester was used to investigate the effect of controlling the pH of the methanogenic stage on the biogas production and the pollution potential reduction of acid cheese whey.
Abstract: A two-stage, no-mix anaerobic digester of 145 L capacity was used to investigate the effect of controlling the pH of the methanogenic stage on the biogas production and the pollution potential reduction of acid cheese whey. The digester was operated at a 15-d hydraulic retention time, and a temperature of 35°C. Controlling the pH of the methanogenic stage increased the biogas production rate and methane yield by 77.77 and 289.00%, respectively. Reductions of up to 32.19, 44.44, and 35.86% in the COD, solids and nitrogen were achieved.
TL;DR: In this article, the economics of biogas systems are compared with traditional heating systems fuelled by wood, coal and wood mixture, and dried animal waste in three different climatic regions in the country.
Patent•
05 Jun 1991
TL;DR: In this paper, a closed column gas scrubber equipped with inlet and outlet for biogas and waste water was used to remove H2S from a closed-column gas mixture.
Abstract: A process for removing H2S from biogas is provided, wherein the biogas is treated with an alkaline scrubbing liquid, the alkalinity necessary for absorption of H2S originating from an aerobic biological waste water treatment plant. Thus, the water/biomass mixture form the aerobic treatment or the clarified effluent can be used as a scrubbing liquid. The water flow/gas flow ratio in the scrubbing process is preferably 0.2 or greater. The liquid wherein H2S is absorbed can be recycled to the aerobic phase for oxidising the H2S. The process can be performed using a closed column gas scrubber equipped with inlet and outlet for biogas, inlet and outlet for treated waste water and means for contacting biogas and waste water.
TL;DR: Amongst the surfactants tested, Tegoprens 43 showed a maximum of more than 114% increase in gas production with a 6·25% higher methane content.
Patent•
18 Dec 1991
TL;DR: In this paper, an anaerobically-operated acidification and biogas reaction was used to treat de-watered sludge which consisted of activated sludge from a settlement tank and prim. sludge.
Abstract: The novelty is that a waste water a treatment process and appts. treats de-watered sludge which consists of a mixt. of activated sludge from a settlement tank and prim. sludge. Further that the plant incorporates an anaerobically-operated acidification reactor, followed by an anaerobically-operated biogas reactor with the following features. (a) Protease, amylase, lipase, cellulase or mixts. thereof are introduced into the acidification reactor, (b) the acidification reactor is operated in the temp. range 20 to 70 deg.C. in a pH range of 3.5 to 6.5. (c) the temp. and the pH value are set in the ranges as stated (b) above, such that the acidified organic sludge contents introduced into the biogas reactor, contain at least 50% minerals; further that a carbon-based substrate consisting mainly of acetic acid is drawn off from the acidification reactor by means of a separator assembly, while the residue of the substance in introduced into the biogas reactor.