Showing papers on "Biogas published in 1978"
TL;DR: In this article, the mesophilic anaerobic digestion was used to evaluate the performance of apples, asparagus, carrots, green peas, French beans, spinach, and strawberries from a canning factory.
Abstract: Waste of apples, asparagus, carrots, green peas, French beans, spinach and strawberries from a canning factory have been screened on mesophilic anaerobic digestion in 90-day experiments at loading rates varying between 0.80 and 1.60 kg volatile solids (VS) m−3 day−1 at a retention time of 32 days. Average biogas yields varied from 0.30 to 0.58 m3 kg-1 VS day−1. High percentages of reduction in VS, carbohydrate and crude fibre were obtained in most experiments. Some waste materials showed unbalanced digestion, as might be expected from carbohydrate-rich substrates. In those cases alkali addition, feed interruption and mixing with a nitrogen-rich substrate were used to overcome unbalanced digestion. Residual solids in the digested sludges were removed by flocculation with a polyelectrolyte and centrifugation; liquids with lower CODs remained after flocculation.
72 citations
TL;DR: In this article, the authors measured the rate and composition of gases released during anaerobic degradation of solid waste and found that the major gases observed in the present study were CO 2, H 2 and CH 4.
Abstract: The rate and composition of gases released during anaerobic degradation of solid waste were measured. From 55 kg to 80.5 kg of solid waste was placed in 208-l containers, sealed, and maintained at different environmental conditions, and the gas production and composition were measured. The major gases observed in the present study were CO\d2, H\d2 and CH\d4. The maximum rate of gas production was 0.18 l/kg.day while the maximum amount of gas produced was 5.7 l/kg.day dry weight during the 300-day testing period. The rate of gas production generally increased with increasing moisture content and temperature and with decreasing solid waste size and density.
71 citations
Patent•
17 Mar 1978
TL;DR: An apparatus for the manufacture of combustible gas consisting principally of methane with minor amounts of carbon monoxide, carbon dioxide and hydrogen from organic wastes comprising an inverted vessel positioned in a body of water in a matter of such that the water acts as a "liquid door" to trap plant material and gas within the vessel is described in this paper.
Abstract: An apparatus for manufacture of combustible gas consisting principally of methane with minor amounts of carbon monoxide, carbon dioxide and hydrogen from organic wastes comprising an inverted vessel positioned in a body of water in a matter of such that the water acts as a "liquid door" to trap plant material and gas within the vessel. The combustible gas manufacturing method provided by the apparatus operates at a temperature of about 21° C. to 37.8° C. Under ideal conditions it is possible to produce as much as about 11 cubic foot of gas per pound of organic waste. A moving current of water agitates the organic material and sweeps the waste products from the bottom of the vessel where they may be recovered and used as fertilizer if desired.
18 citations
01 Jan 1978
TL;DR: In this article, a technological and socioeconomic assessment of anaerobic digester feasibility for small-to mid-size livestock operations was undertaken, and the results indicated that the digested manure may not have the same nutritional value as raw manure, and that the cost of dehydrating the effluennt for refeeding to the same animals could be cost prohibitive for the small to mid-scale farming operation.
Abstract: A technological and socioeconomic assessment of anaerobic digester feasibility for small- to mid-size livestock operations was undertaken. Materials handling presented the greatest obstacle to satisfactory operation of the full-scale systems. Conversion of the biogas to electricity via standard engine-generator sets is capital- and maintenance-intensive. Electrical conversion requires engine-generator sets that can add 30% to the cost of the system, and that have conversion efficiencies of only 10 to 25%. The system becomes more economical if the biogas can be used on site for direct thermal loads, suggesting that the economic feasibility of anaeroic digesters is site specific and should be closely integrated with the total farming operation. If excess engine heat can be recovered from electrical-conversion equipment, and if provisins can be made on the farm to level electrical loads and conserve energy, then the economics are enhanced. Analysis was performed for farms with 100 animal units. Laboratory studies using a 2:1 mixture of dairy manure to Municipal Solid Waste showed that the biogas production per pound of volatile solids added is nearly the same as for straight manure. Addition of the organic portion of MSW to small farm digesters could make marginal systems economically attractive. Preliminary refeed studies indicatedmore » that the digested manure may not have the same nutritional value as raw manure, and that the cost of dehydrating the effluennt for refeed to the same animals could be cost prohibitive for the small to mid-size farming operation.« less
7 citations
Patent•
17 Jul 1978
TL;DR: In this article, the amount of nitrous oxide generated in waste gas from denitrification tank was detected by utilizing the relation between the nitrous dioxide concentration measured and the total nitrogen concentration of waste water in order to control activated sludge process.
Abstract: PURPOSE: To detect the concentration of total nitrogen in waste water indirectly but simply and continuously by measuring the amount of nitrous oxide generated in waste gas from denitrification tank. CONSTITUTION: A part of waste water branched from the main waste water pipe 1 is treated in the nitrification tank 31 and the denitrification tank 32, and a carrier gas, e.g., nitrogen gas, methane gas, etc., is continuously introduced into the denitrification tank 32 to carry along waste gas to the nitrous oxide gas meter 38, e.g., an infrared analyzer, gas chromatographic analyzer, etc., to measure nitrous oxide concentration. The total nitrogen concentration of waste water is detected by utilizing the relation between the nitrous oxide concentration measured and the total nitrogen concentration of waste water in order to control activated sludge process as needed. COPYRIGHT: (C)1980,JPO&Japio
4 citations
30 Jul 1978
TL;DR: In this paper, an economic and technical analysis of gas treatment systems for the handling of 0.1, 1.0, and 3.0 MM Scfd of raw feed gas and product delivery pressures of 125 and 1000 psia were considered.
Abstract: Fuel gas obtained from the anaerobic digestion of waste materials usually needs to be treated before being transmitted in existing pipeline systems. The purification scheme involves the removal of carbon dioxide, hydrogen sulfide, and moisture from the digester gas to meet pipeline specifications. Gas treatment systems for the handling of 0.1, 1.0, and 3.0 MM Scfd of raw feed gas and product delivery pressures of 125 and 1000 psia were considered in this study. From the results of an economic and technical analysis of these systems, physical absorption systems, particularly water scrubbing, were found to be the most economical system for the treatment of digester gas with the flow streams considered. The Fluor Solvent process was economically comparable with the water scrubbing process for high pressure applications, but the value presented had a large uncertainty. The commercial chemical absorption systems were less economical due to high heat requirements for solvent regeneration. Among the chemical absorption processes, the hot potassium systems were found to be more economical than the amine system. The molecular sieve adsorption process was economically similar to the chemical absorption process. The GE membrane separation process was economically comparable for both high and low pressure apllications, but thismore » system has not been evaluated in real-life conditions. Since no kinetic and equilibrium data were available for the phosphate buffer system, estimates had to be assumed. Using what were believed to be very conservative estimates, this chemical absorption process was found to be economically competitive with the water scrubbing process for treating gas with a delivery pressure of 125 psia.The cost analyses in this study were based on the assumption of no recovery of the CO/sub 2/ by-product. It was found that credits for the recovery of the CO/sub 2/ could be significant.« less
3 citations
01 Dec 1978
TL;DR: Two anaerobic digesters have been treating cow manure in Michigan and in Wisconsin for a few years as discussed by the authors, and both of them employ plug-flow, contrasted with stirred-pot, management of the manure and operate at mesophilic temperatures.
Abstract: Two anaerobic digesters have been treating cow manure in Michigan and in Wisconsin for a few years. Both of them employ plug-flow, contrasted with stirred-pot, management of the manure and operate at mesophilic temperatures. They exhibit very high stability and good methane yield at feeding rates in excess of 10 Kg of volatile solids per day per cubic meter of digester volume (0.8 lb/cu ft/day). Dispersion occurs in the velocity of the material passing through the digester so that large pieces pass much more slowly than the hydraulic velocity. Odors in the effluent disappear when hydraulic detention times are as long as 4 days. From measurements of energy content, the biogas is about 60 percent methane. The pH of the digester is between 7.0 and 7.2 under most steady feeding conditions. Under transient feeding conditions it may range from 6.8 to 7.8.
2 citations
01 Dec 1978
TL;DR: In this article, a technological and socioeconomic assessment of anaerobic digester feasibility for small to mid-size livestock operations was undertaken, and three full scale digesters and one pilot scale facility were under various degrees of monitoring and evaluation to assess design and operational problems.
Abstract: 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 digestors Materials handling presented the greatest obstacle to satisfactory operation of the full scale systems Conversion of the biogas to electricity via standard engine-generator sets is capital and maintenance intensive Electrical conversion requires engine-generator sets which can add 30% to the cost of the system, and which have conversion efficiencies of only 10-25% The system becomes more economical if the biogas can be used on site for direct thermal loads, suggesting that the economic feasibility of anaerobic digesters is site specific and should be closely integrated with the total farming operation If excess engine heat can be recovered from electrical conversion equipment, and if provisions can be made on the farm to level electrical loads and conserve energy, then the economics are enhanced Analysis was performed for farms with 100 animal units
30 May 1978
TL;DR: Topics presented include: solid waste to methane gas; pipeline fuel gas from an environmental cattle feed lot; heat treatment of organics for increasing anaerobic biodegradability; promoting faster anaerobe digestion; permselective membrane control of algae and wood digesters for increased production and chemicals recovery.
Abstract: Progress was reported by all contractors. Topics presented include: solid waste to methane gas; pipeline fuel gas from an environmental cattle feed lot; heat treatment of organics for increasing anaerobic biodegradability; promoting faster anaerobic digestion; permselective membrane control of algae and wood digesters for increased production and chemicals recovery; anaerobic fermentation of agricultural residues; pilot plant demonstration of an anaerobic, fixed-film bioreactor for wastewater treatment; enhancement of methane production in the anaerobic diegestion of sewage; evaluation of agitation concepts for biogasification of sewage sludge; operation of a 50,000 gallon anaerobic digester; biological conversion of biomass to methane; dirt feedlot residue experiments; anaerobic fermentation of livestock and crop residues; current research on methanogenesis in Europe; and summary of EPA programs in digestion technology. (DC)
01 Jan 1978
TL;DR: In this article, a bibliography includes 11 major topics covering research dealing primarily with anaerobic digestion, including design parameters, influent, effluent, biogas, operating parameters, laboratory analyses (methods), economics, integrated systems, environmental aspects, social aspects, and general reviews.
Abstract: The bibliography includes 11 major topics covering research dealing primarily with anaerobic digestion. Particular emphasis has been given to anaerobic digestion of farm animal manures. Topics included are: design parameters, influent, effluent, biogas, operating parameters, laboratory analyses (methods), economics, integrated systems, environmental aspects, social aspects, and general reviews. An author index is included.
01 Dec 1978
TL;DR: In this article, the applicability of powdered activated carbon to digesters in the United States was evaluated and the number of stressed digesters estimated, and the results showed that although median values of the operating parameters conformed with those of a well-operated digester, 30% of the surveyed were stressed with regard to at least one important parameter.
Abstract: Bench-scale and pilot plant studies at PNL have shown that powdered activated carbon is effective in improving volatile solids destruction and gas production in anaerobic digesters that are operating at less than normally expected levels of efficiency. To evaluate the applicability of this technology to digesters in the United States, digester operating characteristics at 60 facilities were surveyed and the number of stressed digesters estimated. The results show that although median values of the operating parameters conformed with those of a well-operated digester, 30% of the digesters surveyed were stressed with regard to at least one important parameter. Of the 30 largest treatment plants in the U.S., 7 fell into this category. Digester gas production and usage were then examined to determine the importance of methane off-gas as an energy source. A conservative estimate is that the gas produced nationally represents a heating value of about 2.36 x 10/sup 13/ Btu/year with a present value of $40 million. Of this amount, an estimated 75% is used either onsite or sold. Onsite uses include heating digesters and buildings, incinerating sludge, operating equipment, and generating electricity. The other 25% is flared and the energy value lost. The present value of the flaredmore » gas is about $10 million/year. Natural gas prices are projected to increase 150% over the next 7 years. If the present utilization ratio continues, the flared gas will be worth approximately $27 million in 1985. Presently, digester gas is mainly used for process heating and operating equipment. The technical and economic feasibility of recovering digester gas for electrical power generation, onsite equipment operation, and sales to other consumers (utilities, private companies) should be thoroughly investigated. If fuel gas recovery and utilization are found to be desirable, consideration should be given to expanding and upgrading anaerobic digester facilities in the U.S.« less
01 May 1978
TL;DR: In this article, the authors present an up-to-date information in the OSU Extension catalog: http://extension.oregonstate.edu/catalogs.
Abstract: Published May 1978. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog