Showing papers on "Biogas published in 1981"

Anaerobic digestion process

Abstract: Methane gas produced according to an anaerobic digestion of organic wastes is introduced into digested separated water which is alkalized by a photo-culture of algae, whereby impurity carbon dioxide gas is removed by absorption. Accordingly, methane of high concentration is recovered and at the same time, by-product algae is recycled as feedstock, and thereby improving the yield of methane.

Methane production from agricultural and domestic wastes

Abstract: 1 Introduction.- 2 Methods of production of fuels from biomass.- Physical and physico-chemical methods.- Biological methods.- 3 The microbiology and biochemistry of anaerobic digestion.- The microbial population in general.- The breakdown of carbohydrates.- The breakdown of nitrogenous compounds.- The breakdown of fats.- Minor bacterial reactions.- Methane production.- Factors affecting the rates of growth and activities of digester bacteria and interactions amongst the bacteria.- Conclusions.- 4 Types of digesters: theoretical aspects and modelling of digester systems and deviations from theory.- Biological models.- Systems for use with 'wet' feedstocks.- The batch culture.- Continuous cultures.- Digesters for 'solid' feedstock.- The Engineering Model.- The Economic Model.- 5 Types of digesters being constructed and the operation of digesters.- Starting a digestion.- The single-stage stirred-tank digester.- The small, simple digester.- The Gobar digester.- The Chinese digester.- The large, automated digester.- The sewage digester.- The contact digester.- Anaerobic filters.- The upflow sludge-blanket digester.- The fluidised-bed digester.- Digesters for agricultural wastes and vegetable matter.- Stirred-tank digesters.- 'Solid' feedstocks.- The tubular digester.- Gas-holders and gas handling.- Gas purification.- Uses of digester gas.- Safety precautions and tests with digesters.- 6 Uses of digested sludge.- Use as fertiliser.- Use in animal feedstuffs.- 7 Biogas production-laboratory and pilot-plant experiments.- General-the apparatus.- Domestic sewage.- Domestic garbage.- Industrial wastes.- Other industries.- Conclusions.- Agricultural wastes.- Piggery waste.- Poultry waste.- Cattle waste.- Animal excreta plus other wastes.- Crops and crop residues.- Conclusions.- 8 Energy production by practical-scale digesters.- Domestic and municipal sewage.- Mesophilic digestion.- Thermophilic digestion.- Domestic garbage with sewage sludge.- Other wastes.- Factory wastes.- Meat wastes.- Fruit, vegetable and other crop-processing wastes.- Fermentation-industry wastes.- Farm-animal wastes.- Small digesters.- Large-scale digesters.- 'Energy-crops' and crop residues.- Landfills.- Appendix 1 Photographs of full-scale working digesters.- Appendix 2 Some estimates of wastes available for biogas or other fuel production.- Appendix 3 Glossary of terms.

Production of methanol from organic waste material by use of plasma jet

Abstract: Methanol is produced from an organic waste material such as sewage by a process wherein an arc heater or "plasma jet" performs novel process steps including: (1) partially vaporizing an organic sewage sludge (a semi-liquid material produced by bacterial digestion of the sewage); (2) reacting the gas products obtained by the sludge vaporization, together with a digester gas (obtained by digestion of the sewage), to form a synthesis gas comprising principally H2, CO, CO2, H2 O and CH4, and (3) optionally, driving a water shift reaction to convert a portion of the output gases to additional H2 and CO for use as a feed stream to the jet. The synthesis gas is converted to methanol in a subsequent process step.

Inhibition of anaerobic digestion by organic priority pollutants

Abstract: Inhibition de cultures complexes en anaerobie (digestion de dechets urbains) par 24 composes representatifs des polluants prioritaires organiques semi-volatils

Process for removing contaminants from a stream of methane gas

Abstract: A feed stream of digester gas from an anaerobic process is compressed to a predetermined pressure of about 300 p.s.i.g. and fed into an absorber at that pressure. Carbon dioxide and hydrogen sulfide impurities of this feed stream are absorbed in the absorber by counterflowing water. Water from the absorber may be fed back to an activated sludge sewage treatment facility where the hydrogen sulfide is oxidized and the carbon dioxide released. As an alternative to the absorber, hydrogen sulfide is oxidized in an iron sponge reaction. Alternately, these contaminants are stripped with air and vented. Treated gas from the absorber, essentially methane, is either compressed for introduction into storage tanks, or dried and used as pipeline gas. In the dryer, adsorbed moisture is removed by air, followed by a purge with treated gas.

Compost filters for H/sub 2/S removal from anaerobic digestion and rendering exhausts

Abstract: A system for the disposal of anaerobic digester gas from meat waste treatment plants has been developed as an alternative to atmospheric disposal. Hydrogen sulfide waste gases are filtered through by-product compost. Operation and effectiveness of such a treatment process are detailed. (2 diagrams, 5 references, 4 tables)

Biogas production from mixtures of cattle slurry and pressed sugar cane stalk, with and without urea.

Abstract: Eight two-litre glass jars were used as anaerobic digesters in a trial to compare biogas production from mixtures of cattle slurry and pressed sugar-cane stalk. It was found that as the percentage of pressed cane stalk (PCS) was increased, the initial pH of the mixture decreased and initial gas production was impaired. The PCS was degraded much more slowly than the cattle slurry, although total production was not reduced significantly by the presence of up to 56.7% PCS (dry-matter basis) in the fermentation mixture. Gas production was seriously reduced when the level of PCS rose to 80%. Initial pH of this mixture was 4.6 and 4.4 for the treatments with and without urea respectively. The addition of urea had the effect of increasing pH, and substantially reducing the length of the lag phase of the cumulative biogas production curves. The economics of the production of biogas (a mixture of approximately 60% methane: 40% carbon dioxide) are becoming more favourable as oil and fertilizer prices rise. Furthermore, biogas production units provide a decentralized fuel supply and waste management system,both of which are becoming increasingly attractive, particularly in rural areas of developing countries. The majority of work done on biogas has used animal wastes as the raw material. Additives to this basic raw material can be viewed from two points of view - either as ameliorators of gas production, by improving conditions for gas production, or as a means of utilising potential gas producing wastes. Amongst such non animal-origin wastes are coffee pulp, straw and domestic rubbish. Some raw materials with potential for methane generation are listed in Table 1. (National Academy of Sciences 1977). This study arose as part of an investigation into an integrated crop/ livestock/energy system whereby sugar cane, as a high yielding crop, would form the basis of the diet of confined cattle in which it is proposed that the sugar cane juice, which is high in metabolizable energy, would be fed to the cattle and the cattle slurry would be used for biogas production, and after digestion as a fertilizer. Although there are several ways in which the pressed cane stalk residue could be utilized (eg to make charcoal, producer gas, particle board or paper) one simple alternative would be to chop it and add it to the slurry in the digester to augment biogas production. This study was designed to show by how much slurry could be substituted by pressed cane stalk, by monitoring its effect on pH and biogas production.

Biogas from coffee pulp

Abstract: Coffee pulp, traditionally considered a highly polluting waste, is evaluated for its potential as biogas substrate via anaerobic digestion. The fibrous nature of the material required long retention times.

Container for the storage of gas under low pressure, especially bio gas

Abstract: Tank for the storage of gas under low pressure, in particular biogas, which is produced by anaerobic fermentation from organic matter, such as stable manure or liquid manure. The tank (1, 2, 3, 4) contains an inner wall with a membrane (5) from for instance soft and flexible, thin PVC which can be loaded on the one hand with ballast, such as water (7) and/or stones (6) and the like, and can be placed on the other hand under increased pressure of a fluid F, such as air, by means of a blower (15) with a conduit (14), whereas the pressure of the biogas (G) can be decreased by means of a suction blower (12) until a suitable balanced position of the inner wall is obtained. The inner wall can exist either wholly out of the membrane (5) (fig. 1 and 2) or partly from a border membrane (5a) with a central solid middle part (9) (fig. 3 and 4).

Device for treating biomass to recover methane gas

Abstract: A device for treating biomass from any organic materials for methane gas recovery by anaerobic fermentation is characterised in that a water-cooled internal combustion engine (1) fulfils three main functions: that of the shredder drive (2), that of the stirrer drive (3) in conjunction with a rake (4) for destroying floating covers, and that of digestion tank heating (5) which is designed as direct heating by waste gas heat and is controlled via a thermostat circuit (9), by giving the pulse for starting and stopping the internal combustion engine (1), and in that the engine waste heat (12) and the waste gas heat (11) of the internal combustion engine (1) additionally serve for heating the process water, and furthermore characterised in that, in relatively large plants with power generation from biogas, the generator motor (13) undertakes the function of the digestion tank heating (5) by its waste gas heat, in that the waste gas heat (15) additionally serves for heating the process water and in that a heating circulation is connected to the water cooling system (16) of the generator motor (13), and furthermore characterised in that an effective insulating layer (8) of rigid foam around an iron skeleton frame (17) surrounds the digestion tank (7) as a unit, fixes the holders (18) of the heating coils (5) and serves as a tightly closed protection trough and as transport packaging or external design of a compact unit ready for connection.

Crop residue conversion to biogas by dry fermentation.

Abstract: A simple 'dry fermentation' process has been developed that may enable economical conversion of drier crop residues to biogas. Results from two years of process definition and scale-up to a 110 m/sup 3/ prototype show that biogas production rates exceeding those necessary to make the dry fermentor competitive have been achieved. 13 refs.

Process and apparatus for mixing biomass

Abstract: In the process, biomass (10) stored in a heatable biogas reactor (1) in an oxygen-free atmosphere is mixed by blowing in biogas (11) intermittently. The biogas pressure (11) which is required for this purpose is generated by bacterial strains in a biogas reactor (1), which is sealed towards the outside and is connected to a biogas pressure vessel (4), is built up in the biogas pressure vessel (4) and is subsequently blown from the latter into the biomass (10). The biogas (11) is subsequently discharged to a biogas store (7).

Bio:reactor for methane gas prodn. from organic substances - pretreated with amylase, lipase and protease, comprising separate fermentation chambers with circulation of biomass under gas pressure

Abstract: In a new bioreactor for rotting down organic substances to produce methane gas, (a) before introducing into the bioreactor the biomass is prefermented with the enzymes amylase, lipase and the proteases trypsin, chymotrypsin, elastase and carboxypeptidase to break down cyclic hydrocarbon molecules to short, readily-degradable open-chain molecules; (b) methane bacteria of the desired mesophilic type are cultivated separately on nutrient solution in a separate process to avoid degenerative effects arising from inoculation of fresh sludge with old sludge; (c) the biomass is hygienized by basifying to pH 12 with CaO and exothermic heating at 70 deg.C for 30 mins; (d) the biomass is rotted separately for the entire duration of composting in 12 individual chambers so that the development of methane bacteria is not inhibited by continuous charging; (e) the biomass is cycled through the serially arranged rotting chambers using biogas at the operating temp. of 38 deg., the chambers being fitted at 1-day or 2-day intervals; (f) all the chambers are arranged in series, linked by a closed pipe system, but the pH of each chamber is individually automatically regulated to pH7 by addn. of lime water; and (g) the biomass reactor is fitted with a double mantle and biomass temp. is held constant throughout the process using a thermostatted heating system. The measures outlined above ensure that development of methane-generating bacteria is undisturbed. Gas yields are high, CO2 content is low, and reaction time for 80% gas yield is reduced to 6 days.

Treatment of organic waste

Abstract: PURPOSE:To reduce the size of a solid-liquid separating vessel and reduce treating time by separating the digesting liquid from an anaerobic digester to digested sludge and desorbed liquid by a pressure flotation method in an anaerobic state and returning the whole or part of the digested sludge to the digester. CONSTITUTION:Sewage sludge and the like are charged into an anaerobic digester 1, where they are brought into contact with anaerobic germs and are treated under prescribed conditions. The digester gas produced in the digester 1 is stored in a gas holder 3. The digesting liquid is introduced into a flotation tank 4. The digester gas of the holder 3 is fed into the blow port of a pressurizing pump 9 or pressurizing water producer 7 by a compressor 8, and the desorbed liquid obtained by the solid-liquid separation of the tank 4 is fed therein from a desorbed liquid receiving vessel 10. These are pressurized with the device 7 to dissolve the digester gas and the gas is joined with the digesting liquid in the tank 4 through a pressure reducing valve 6. Thereby, the digester gas is made into fine bubbles which stick on solids and float, whereby the solid-liquid separation is accomplished. The floating digested sludge is charged into the digester 1 in an anaerobic state, and the floating digester gas is stored in a gas holder 5.

Process for liquefying biogas

Abstract: In a process for liquefying biogas, the biogas constituents methane, carbon dioxide and water are reacted, without separation and, where appropriate, with the addition of supplementary water, endothermically over a catalyst to give synthesis gas having a carbon monoxide/hydrogen ratio of between 1:1 and 3:1. Subsequently, the synthesis gas is converted exothermically, using hydrogenation catalysts at a controlled temperature, into liquid hydrocarbons, some of which contain oxygen.

Process and apparatus for producing biogas

Abstract: The invention relates to a process and an apparatus for obtaining biogas from organic substances such as straw, farmyard manure and the like. According to the invention, the floor of a pig, cattle or poultry house is used as heat exchanger area through which the body heat of housed livestock can be delivered to slurry or other organic substance which can be introduced into cavities in the floor.

Prodn. of methane from agricultural waste - using two stage process with initial acid stage followed by alkaline fermentation

Abstract: Treatment of a biomass such as liq. manure, manure or abattoir waste for conversion to biogas (2/3 CH2, 1/3 CO2), comprises a initial stage which is carried out under acid conditions (pH5).The subsequent stage of the process is under alkaline to neutral conditions. The reactor contains an inner vessel for the acidic reaction. Residence time in the acid stage is ca. -3 days. The feed enters the acid reactor from the base and overflows from the top. For use on forms or other agricultural establishments, and pref provides a profitable method for using form waste with good gas yield.

Energy conservation for existing wastewater treatment plants

Abstract: There is a need for energy conservation wastewater treatment and opportunities for conserving energy in existing facilities are examined. Target areas include pumping adjustments; pump maintenance and operation; plant lighting, heating, and ventilation; sludge pumping; trickling filters; rotating biological contactors; and activated sludge. Effects on overall energy utilization of solids retention time, of intermittent operation of the sludge dewatering process, and of anaerobic digestion are examined. Use of recovered anaerobic digester gas and solar energy are noted.

Process and system for obtaining biogas by methane fermentation

Abstract: The invention relates to a process and a system for obtaining biogas by methane fermentation, wherein decaying matter, for example farm slurry, is passed from a reservoir after preheating into a fermentation tank and there heated to the fermentation temperature, and the escaping biogas is passed into a gas tank. The invention has the object of developing a process of this type and a system for carrying out this process, with which an economic heating of the decaying matter to the particular desired fermentation temperature of 33 DEG C or 54 DEG C is ensured with lower investment costs. This object is achieved according to the invention by heating the decaying matter to the fermentation temperature by incinerating dried slurry and transferring the resulting amounts of heat. A particularly advantageous system for carrying out this process is characterised in that a heat transfer device (4) is located in the fermentation tank (3) and is connected via a water circulation (23, 26) to a boiler (7) in which the dried slurry can be incinerated. The use of the present process and its system for carrying out this process is possible in principle for obtaining biogas from all liquid decaying matter amenable to drying.

Process and apparatus for utilization of products of vital activity of animals

Abstract: PROCESS AND APPARATUS FOR UTILIZATION OF PRODUCTS OF VITAL ACTIVITY OF ANIMALS Abstract of the Disclosure The process according to the present invention comprises a decompression treatment of manure prior to anaerobic fer-mentation carried out under conditions of a controlled reduced pressure; the evolving biogas and other nitrogen- and carbon-containing components, after separation thereof from air ex-hausts from the cattle house and from the liquid fraction of manure are employed as trophic elements of the culture medium in an aerobic process for the treatment with prototrophic bacteria. The biomass of the latter is disintegrated and used as a feedstuff component; the gas mixture resulting from the treatment with prototrophic bacteria is used as a heat-trans-fer agent in the system of anaerobic fermentation, while the fermented mass is precipitated by means of an organo-mineral suspension prior to separation into fractions. An apparatus for the treatment of manure comprises an anaerobic microbiological reactor with fermentation and accu-mulation vessels provided with a heating system, as well as means for supply of manure and withdrawal of the fermented mass, the latter means being connected with the means for separation of the fermented mass into the solid and liquid fractions, the accumulation vessel has means for withdrawal and purification of the biogas; the accumulation vessel is connected, through the means for withdrawal of the biogas, with the aerobic microbiological reactor having a disintegra-tor of the biomass, a concentrator, an outlet pipe for with-drawal of the spent biogas into the system of preheating of the fermentation vessel, and the anaerobic microbiological re-actor has a device for automatic control and monitoring of the fermentation process intensity.

Methane gas from swine manure

Abstract: The following topics are discussed: the basic anaerobic digestion process, manure quality, system components, anaerobic digester types, digester design and operation, digester start-up and operation, gas yields, gas scrubbing systems, gas use strategies, nutrient recovery and use, and the economics of methane production systems. (MHR)