Showing papers on "Biogas published in 1979"

Low Temperature Anaerobic Digestion of Swine Manure

Abstract: Anaerobic digestion of swine manure at low process temperatures was studied in two pilot-scale experiments where the effect of process temperature was evaluated in terms of biogas production, COD removal, and volatile solids destruction. The first experiment compared 25°C digestion with 35°C to 40°C digestion while the second experiment evaluated various solids retention times for digestion. Gas production rates were comparable to those reported in the literature for domestic sewage sludge digestion at low temperatures. In addition, the relative stability of low temperature digestion as measured by unionized volatile acid concentrations was good when compared to digestion at higher temperatures.

Methane generation by anaerobic digestion of cellulose-containing wastes

Abstract: The anaerobic digestion of cellulose-containing wastes, both municipal and agricultural, holds promise as a dual method of energy (methane) generation and waste treatment. Advances regarding the technical biochemistry and microbiology of this anaerobic-digestion process are reviewed. Experimental results concerning the kinetics of methane generation from various substances and the dependence of methanogenesis on operating parameters are assessed. Deficiencies in our present knowledge and areas of future research needs are identified. The feasibility of the process for farm-scale applications are examined.

A pilot scale anaerobic upflow reactor treating distillery wastewaters

Abstract: A two-stage pilot reactor has been tested for the anaerobic digestion of distillery wastewater with a COD of-10,000 mg/1. In the first stage (residence time 16–72 hours), carbohydrates are fermented to low molecular weight metabolites. The second stage is an upflow reactor (residence time 14 hours) in which these metabolites are converted to biogas. Overall COD elimination is 84% (BOD, 92%) with biogas production 5–7 times the active volume of the upflow reactor per day. The process withstands temporary stress conditions fairly well. The results indicate that anaerobic treatment in the upflow reactor qualifies as an efficient and low cost method for distillery wastewater treatment.

Waste gas purification systems and methods

Abstract: Systems and methods for directing waste gases to a by-pass conduit from a conduit to a waste gas purifier in response to signals indicating predetermined conditions which are harmful to the waste gas purifier to which the waste gases are normally directed while at the same time maintaining a substantially uniform pressure at the source of the waste gases. Preferably, the source of the waste gases is a scrubber unit for a maleic anhydride production unit. The waste gas purifier is preferably a catalytic oxidation unit for oxidizing hydrocarbons and carbon monoxide in the waste gases.

Agricultural anaerobic digesters: design and operation

Abstract: The following are discussed: microbial and chemical processes, design and function of the digester system, operational procedure, storage and use of biogas and effluent, and costs of anaerobic digestion and biogas production from dairy barn manure (MHR)

Increased methane production in biogas

Abstract: Different plant wastes containing digestible volatile solids were tested in admixture with gobar (dung) for their effect in increasing methane output in anaerobic digestion. A mixture of gobar, algae and waterhyacinth in 1 : 1 : 1 proportion produced 79% methane. Parameter affecting the biogas production kinetics are described.

Process for methane and ammonia extraction from organic waste

Abstract: A process for extracting methane gas and ammonia from raw material, such as organic waste. The process is carried out in a closed container or digester by anaerobic bacteria. The yield of the conventional anaerobic bacteria digestion process is greatly increased by the novel step of maintaining the space in the digester above the level of the raw material at a pressure below atmospheric during the digestion process.

Studies in biogas technology. Part IV. A novel biogas plant incorporating a solar water-heater and solar still

Abstract: A reduction in the heat losses from the top of the gas holder of a biogas plant has been achieved by the simple device of a transparent cover. The heat losses thus prevented have been deployed to heat a water pond formed on the roof of the gas holder. This solar-heated water is mixed with the organic input for ‘ hot-charging ’ of the biogas plant.

Replacement of cowdung by fermentation of aquatic and terrestrial plants for use as fuel, fertilizer and biogas plant feed

Abstract: With 85% of the entire Indian population living in villages and 98% of the household energy requirement of the rural population demanded for cooking, research was undertaken on the supply of biomass for those Indians who do not have cattle. This research was carried out on the fermentation of aquatic and terrestrial plants for use in biogas generation. The plants utilized for biogas generation are: water hyacinth, water lettuce, African payal, duck weed, water spinach, cattail ramban, ipil-ipil, morning glory, paragrass, purple nutsedge, and durva grass.

The Sampling and Gas Chromatographic Analysis of Gases from Landfill Sites

Abstract: The safe development of landfill sites is daily increasing in importance. In this context the analysis of soil gases. especially for methane. is vital. Techniques have been developed for the sampling of such gases. and their subsequent analysis at the v.p.m. level by gas chromatography. Factors affecting the gas concentrations are considered.

Studies in biogas technology. Part I. Performance of a conventional biogas plant

Abstract: This paper gives an account of a conventional 5.66 m3/day (200 cubic ft/day) biogas plant which has been instrumented, operated and monitored for 2 1/2 years. The observations regarding input to the plant, sludge and biogas outputs, and conditions inside the digester, have been described. Three salient features stand out. First, the observed average daily gas yield is much less than the rated capacity of the plant. Secondly, the plants show ease of operation and a very slow response to reductions and cessations of dung supply. Thirdly, the unexpectedly marked uniformity of density and temperature inside the digester indicates the almost complete absence of the stratification which is widely believed to take place; hence, biogas plants may be treated as isothermal, ‘ uniform ’ density, most probably imperfectly mixed, fed-batch reactors operating at the mean ambient temperature and the density of water.

Studies in biogas technology. Part III. Thermal analysis of biogas plants

Abstract: A thermal model for a conventional biogas plant has been developed in order to understand the heat transfer from the slurry and the gas holder to the surrounding earth and air respectively. The computations have been performed for two conditions : (i) when the slurry is at an ambient temperature of 20°C, and (ii) when it is at 35°C, the optimum temperature for anaerobic fermentation. Under both these conditions, the gas holder is the major “culprit” with regard to heat losses from the biogas plant. The calculations provide an estimate for the heat which has to be supplied by external means to compensate for the net heat losses which occur if the slurry is to be maintained at 35°C. Even if this external supply of heat is realised through (the calorific value of) biogas, there is a net increase in the biogas output, and therefore a net benefit, by operating the plant at 35°C. At this elevated temperature, the cooling effect of adding the influent at ambient temperature is not insignificant. In conclusion, the results of the thermal analysis are used to define a strategy for operating biogas plants at optimum temperatures, or at higher temperatures than the ambient.

Can biogas provide energy for India's rural poor —

Abstract: or will it benefit only richest 10–12% of rural families? Anil Agarwal reports on the Janata government's plans to promote the use of biogas plants

Biogas A Decentralised Energy System-A Pilot Investigation Project

Abstract: A Pilot Investigation Project P B Ghate This paper discusses the advantages of large size community biogas plants over smaller individual family plants. It describes a pilot project, still under implementation at the time of writing, designed to investigate these advantages, and discusses results observed so far on the basis of preliminary cost data. The question of scale economies is discussed in some detail It also discusses the economic or social viability of a biogas based decentralised energy system such as this one and the charges that might have to be levied to achieve financial viability. The last part of the paper attempts to assess the role of such a system is meeting rural energy needs, especially for irrigation pumping, when viewed in relation to the electricity and diesel alternatives; BIOGAS (gobargas) is the cumbustible gas produced by the anaerobic fermentation of cellulose containing organic materials such as cattle dung, crop residues and vegetable wastes, water hyacinth, etc. The biogas plants currently being extended in India consist of a well-shaped brick masonry digester into which a cowdung and water mixture is introduced through an inlet pipe. Gas collects in an inverted steel drum,. or gas holder, which floats on the slurry and from which the gas is led off through a pipe at the top. The spent slurry is displaced automatically through an outlet pipe and is as rich in nitrogen (N), phosphorous (P) and potassium (K) as farm yard manure. While about 50,000 small family size plants have been installed around the country (with daily gas production capacities ranging typically from 2 to 10 cubic matres) very few community plants have been installed so far largely because of the formidable organisational and managerial problems involved. 1 The advantages of large size community plants, however, are fairly well recognised.

Studies in biogas technology. Part II. Optimisation of plant dimensions

Abstract: In this paper, the design basis of the conventional Khadi and Village Industries Commission biogas plants has been elucidated. It has been shown that minimisation of the cost of the gas holder alone leads to the narrow and deep digesters of conventional plants. If instead, the total capital cost of the gas holder plus digester is minimised, the optimisation leads to wide and shallow digesters, which are less expensive. To test this alternative, two prototype plants have been designed, constructed and operated. These plants are not only 25–40% cheaper, but their performance is actually slightly better than the conventional plants.