Showing papers on "Biogas published in 2000"
TL;DR: The technology of anaerobic digestion of organic solid wastes is, in many aspects, mature and its relation to composting technology is examined in this review.
1,725 citations
TL;DR: In this article, a technical evaluation of stillage characterization, treatment, and byproduct recovery in the ethanol industry was performed through a review of the scientific literature, with particular emphasis on solutions pertinent to a cellulosic-based ethanol production system.
Abstract: A technical evaluation of stillage characterization, treatment, and by-product recovery in the ethanol industry was performed through a review of the scientific literature, with particular emphasis on solutions pertinent to a cellulosic-based ethanol production system. This effort has generated substantial information supporting the viability of anaerobic digestion for stillage treatment followed by land application on biomass crops for nutrient recovery. Generally, the characteristics of stillage from cellulosic materials appear comparable to those of conventional sugar- and starch-based feedstocks. However, the data on cellulosic stillage characteristics and treatment parameters are extremely limited and highly variable. This has significant impacts on the capital costs and biogas recovery of anaerobic treatment systems predicted from these data. In addition, technical questions remain unanswered with regard to stillage toxicity from untested feedstocks and the impact of heavy metal leaching when acid hydrolysis reactors are fabricated from corrosion-resistant alloys. Thermophilic anaerobic digestion of ethanol stillage achieves similar treatment efficiencies and methane yields compared to mesophilic treatment, but at almost twice the organic loading rate. Therefore, application of thermophilic anaerobic digestion would improve process economics, since smaller digesters and less stillage cooling are required. Downstream processes for stillage utilization and by-product recovery considered worthy of continued investigation include the production of feed (from single cell protein and/or algae production), color removal, and production of calcium magnesium acetate. This study finds that sustainable and economically viable solutions are available for mitigating the environmental impacts which result from large-scale biomass-to-ethanol conversion facilities. However, further research in some areas is needed to facilitate successful implementation of appropriate technology options.
599 citations
TL;DR: In this paper, a study was made on the development of digestion capacity for solid waste in Europe, which 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.
484 citations
TL;DR: Experimental results obtained emphasize that the response of metabolites was a more useful indicator than hydrogenic activity for obtaining efficient hydrogen production, and expressions of contour plots indicate that Response‐Surface Methodology may provide easily interpretable advice on the operation of a hydrogen‐producing bioprocess.
Abstract: The pH and hydraulic retention time (HRT) of a chemostat reactor were varied according to a central composite design methodology with the aim of modeling and optimizing the conversion of starch into hydrogen by microorganisms in an anaerobic digested sludge. Experimental results from 23 runs indicate that a maximum hydrogen production rate of 1600 L/m(3)/d under the organic loading rate of 6 kg starch m(3)/d obtained at pH = 5.2 and HRT = 17 h. Throughout this study, the hydrogen percentage in the biogas was approximately 60% and no methanogenesis was observed. while the reactor was operated with HRT of 17 h, hydrogen was produced within a pH range between 4.7 and 5.7. Alcohol production rate was greater than hydrogen production rate if the pH was lower than 4.3 or higher than 6.1. Supplementary experiments confirm that the optimum conditions evaluated in this study were highly reliable; while a hydrogen production yield of 1.29 l H(2)/g starch-COD was obtained. An examination of the response surfaces, including hydrogen, volatile fatty acids (VFA) and alcohols production, led us to the belief that clostridium sp. predominated in the anaerobic hydrogen-producing microorganisms in this study. Experiment results obtained emphasize that the response of metabolites was a more useful indicator than hydrogenic activity for obtaining efficient hydrogen production. Furthermore, expressions of contour plots indicate that Response-Surface Methodology may provide easily interpretable advice on the operation of a hydrogen-producing bioprocess.
475 citations
TL;DR: The first full-scale plant for sludge disintegration through Cambi thermal hydrolysis was started up in Hamar, Norway at the end of 1995 as mentioned in this paper, where sludge is directly heated by live steam.
306 citations
TL;DR: In this paper, the effect of an ozone pretreatment on the anaerobic digestion of sewage sludge was investigated and the results indicated that the ozone treatment appeared compatible with subsequent digestion of biosolids and economically feasible.
283 citations
TL;DR: Investigation of the biological hydrogen production potential of individual organic fraction of municipal solid wastes by batch experiments found carbohydrate produced the most hydrogen through biological hydrogen fermentation compared with proteins or lipids.
260 citations
TL;DR: The presence of organic waste residues improves the dewaterability measured as specific resistance to filtration but this positive effect is attenuated if the particle size of the solids is reduced.
253 citations
TL;DR: The biogas potential of manure could be significantly increased by treatment of the recalcitrant organic matter (biofibers) contained in the manure by combination of maceration, chemical treatment, and biological treatment.
221 citations
TL;DR: Results from the macerators indicate that the biodegradability of the fibers is rather enhanced by shearing which is not necessarily reflected by a change in fiber size, and achange in biogas potential was not correlated to a smaller size of the fiber.
188 citations
TL;DR: A minor change in the amount of carbohydrates in the substrate had drastic effects on the buffering effect of the system, and pH was compared with alkalinity, gas production rate, gas composition and the concentration of volatile fatty acids (VFA).
Abstract: The system investigated in this study is an anaerobic digester at a municipal wastewater treatment plant operating on sludge from the wastewater treatment, co-digested with carbohydrate-rich food-processing waste. The digester is run below maximum capacity to prevent overload. Process monitoring at present is not extensive, even for the measurement of on-line gas production rate and off-line pH. Much could be gained if a better program for monitoring and control was developed, so that the full capacity of the system could be utilised without the risk of overload. The only limit presently set for correct process operation is that the pH should be above 6.8. In the present investigation, the pH was compared with alkalinity, gas production rate, gas composition and the concentration of volatile fatty acids (VFA). Changes in organic load were monitored in the full-scale anaerobic digester and in laboratory-scale models of the plant. Gas-phase parameters showed a slow response to changes in load. The VFA concentrations were superior for indicating overload of the microbial system, but alkalinity and pH also proved to be good monitoring parameters. The possibility of using pH as a process indicator is, however, strongly dependent on the buffering capacity. In this study, a minor change in the amount of carbohydrates in the substrate had drastic effects on the buffering effect of the system.
Patent•
26 Jun 2000
TL;DR: In this article, a process to recover energy, reduce pollution potential, and add value to organic waste such as animal manure is described, which involves the anaerobic digestion of feedstocks such as manure, at low to high temperatures in batch, semi-continuous or continuous reactors.
Abstract: A process to recover energy, reduce pollution potential, and add value to organic waste such as animal manure is described. The process involves the anaerobic digestion of feedstocks, such as animal manure, at low to high temperatures in batch, semi-continuous or continuous reactors. The process makes use of existing handling and storage equipment at the farm and requires minimal supervision and skill by the operator. The system is not affected by high concentrations of volatile acids and ammonia or nitrogen. The productivity of the anaerobic digester system, in terms of methane a gas production and quality, is exceptionally high. The anaerobic digester requires only a singe reaction vessel. Consequently, the process is low cost and does not interfere with regular farm operations.
TL;DR: In this article, a batch digestion of municipal garbage was carried out under room temperature conditions (26±4°C) for 240 days and the ultimate gas yields obtained from municipal garbage compared well with the yields obtained by other types of solid wastes.
TL;DR: No accumulation of volatile fatty acids in the treated sludge was observed under aerobic conditions while significant amounts of them were accumulated under microaerobic conditions, and production of biogas on anaerobic digestion of the microaerobically-pretreatedSludge was increased by 1.5 when compared with the sludge without pretreatment.
TL;DR: The widespread introduction of anaerobic digestion in Germany has shown that biogenic organic wastes are a valuable source for energy and nutrients.
Abstract: Anaerobic treatment processes are especially suited for the utilization of wet organic wastes from agriculture and industry as well as for the organic part of source-separated household wastes. Anaerobic degradation is a very cost-effective method for treating biogenic wastes because the formed biogas can be used for heat and electricity production and the digester residues can be recycled to agriculture as a secondary fertilizer. Anaerobic technology will also be used for the common treatment of wastes together with renewable energy crops in order to reduce the CO2-emissions according the Kyoto protocol. Various process types are applied in Germany which differ in material, reaction conditions and in the form of the used reactor systems. The widespread introduction of anaerobic digestion in Germany has shown that biogenic organic wastes are a valuable source for energy and nutrients. Anaerobic waste treatment is done today in approx. 850 biogas plants on small farm scale as well as on large industrial scale with the best beneficial and economic outcome. Due to some new environmental protection acts which promote the recycling of wastes and their utilization for renewable energy formation it can be expected that several hundreds new biogas plants will be built per year in Germany. In order to use the synergetic effects of a combined fermentation of wastes and energy crops new process types must be developed in order to optimize the substrate combinations and the process conditions for maximum biodegradation.
TL;DR: In this article, the authors investigated the biogas production from a slurry obtained by mixing finely ground olive pomace in water using anaerobic digesters of 1-l working volume at 37°C.
Abstract: Biogas production from a slurry obtained by mixing finely ground olive pomace in water was investigated using anaerobic digesters of 1-l working volume at 37°C. A start-up culture was obtained from a local landfill area and was adopted to the slurry within 10 days at this temperature. The biogas generation rates were determined by varying the total solids (TS) concentration in the slurry and the hydraulic retention time (HRT) during semi-continuous digestion. The maximum rate was found to be 0.70 l of biogas per l of digester volume per day, corresponding to a HRT of 20 days and 10% TS with a yield of 0.08 l biogas per g chemical oxygen demand (COD) added to the digester. The methane content of the biogas was in the range of 75–80% for both batch and semi-continuous runs, the remainder being principally carbon dioxide.
TL;DR: In this paper, 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.
TL;DR: In this paper, the authors investigated the effect of BSS inhibition on the performance of the biomethanation process and found that with 16% TS inhibition, a 50-60% loss in biomethane efficiency was observed.
TL;DR: A theoretical feasibility study showed that in Switzerland there is a short term potential on STP's for the codigestion of about 120,000 tons of biogenic wastes per year without big investments.
TL;DR: In this article, a study was conducted to determine the methane production characteristics of low-concentration liquid swine waste using conventional dispersed growth anaerobic fermentation at 35°C.
TL;DR: The BIOCEL process is a mesophilic dry anaerobic batch digestion system for solid organic wastes as discussed by the authors, which is used to process 50,000 tons of biowaste from source separation per year.
TL;DR: The results proved a higher activity of the thermophilic sludge after the addition of glucose, acetate and propionate in comparison with the mesophilicSludge; the maximum methane production rates and the methane yield of the raw sludge were always higher under thermophile conditions; the stability of the degradation process at an increased substrate load was also better.
TL;DR: The study shows that OLR up to 6 kg TVS/m3d can be applicable for the medium selected fraction, while for the MS-OFMSW alone this limit can be doubled, and suggests the use of the double phase process to give more stable conditions.
TL;DR: Bioconversion of municipal solid waste-sludge blend by conventional high-rate and two-phase anaerobic digestion was studied to show that this process exhibited a higher methane yield, and produced aHigher methane-content digester gas than those obtained by single-stage, high- rate anaer aerobic digestion.
TL;DR: A comparison with a one-phase system is carried out, showing that a two- phase system is much more appropriate for the digestion of this kind of highly biodegradable substrate in thermophilic conditions.
TL;DR: To evaluate the potential toxicity of such surfactants on anaerobic sludge, a co-substrate, an easily biodegradable compound in anaerilic conditions, has been added to the samples to test and the effects on biogas production have been determined.
TL;DR: The thermal hydrolysis process allows a complete energy recovery from organic waste, especially suited for wet organic waste and biosolids that are difficult to compost, such as food scraps, biological waste from compact residential areas and sewage sludge.
TL;DR: The results indicate that anaerobic treatment was possible for all the wastewaters studied and the biogas produced had a high methane content.
Abstract: The anaerobic treatability and methane generation potential of the wastewaters of the three important agro-industries in Turkey, namely, cheese-making, poultry breeding and the olive-oil mill industries were studied. Biochemical methane potential (BMP) experiments were conducted for different initial chemical oxygen demand (COD) concentrations. The results indicate that anaerobic treatment was possible for all the wastewaters studied and the biogas produced had a high methane content.
TL;DR: In this article, a fuel cell energy recovery system for anaerobic digester waste water (sewage) treatment plants has been proposed, which can achieve electrical output levels close to full power (200 kW) with measured air emissions comparable to those obtained by a natural gas fuel cell.
TL;DR: In this paper, the behavior of a sanitary landfill was reproduced in a pilot plant under controlled conditions, and the experiment was carried out in an opaque PVC reactor at 36±1°C with recirculation of the leachates.