Showing papers on "Biogas published in 1992"

Biogas processes for sustainable development

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Anaerobic Digestion of Fruit and VegetableProcessing Wastes for Biogas Production

Abstract: The effect of feeding different fruit and vegetable wastes, mango, pineapple, tomato, jackfruit, banana and orange, was studied in a 60-liter digester by cycling each waste every fifth day in order to operate the digester as and when there was supply of feed. The characteristics of the anaerobically digested fluid and digester performance in terms of biogas production were determined at different loading rates (LR) and at different hydraulic retention times (HRT), and the maximum biogas yield of 06 rrd/kg VS added was achieved at a 20- day HR T and 40 kg TS m- 3day- 1 loading rate. The hourly gas production was observed in the digesters operated at 16 and 24 days HRT. The major yield (74"5%) of gas was produced within 12 h of feeding at a 16-day HRT whereas at a 24-day HRT only 59~93% of the total gas could be obtained at this time.

Anaerobic co‐composting of municipal solid waste and waste sludge at hlgh total solids levels

Abstract: The feasibility of anaerobic co‐composting of waste activated sludge (WSS) and simulated organic fraction of typical North‐American municipal solid waste (NA‐MSW), rich in lignocellulosics, at high total solids (TS) content, was examined. Sixteen semicontinuous reactors were run, at 4 levels of TS (25, 30, 35 and 40%), 2 levels of retention time (15 and 21 days), 2 temperature regimes (mesophilic at 39°C and thermophilic at 53°C), and 2 ratios of MSW‐to‐WSS (1: 1 and 2: 1 on total weight basis). Reactors operated at 35% TS and 21 days gave the best organic matter removal efficiencies (up to 44% and 53% on volatile solids basis, for mesophilic and thermophilic regimes respectively) and highest biogas productivities (up to 6 L kg‐1 reactor content day‐1). The methane concentration in biogas was between 55 and 60%. Successful thermophilic reactors generated 15 to 30% more biogas than the corresponding mesophilic digesters. Instability and failure of some thermophilic reactors at 15 days retention ti...

Compact automated displacement gas metering system for measurement of low gas rates from laboratory fermentors.

Abstract: An automated metering system was developed for measuring biogas production from laboratory scale biogas digestors. The gas metering system is based on the principle of liquid displacement with a 100-mL reversible cycle and registration. The gas meter is made entirely of plastic and rubber materials resistant to the corrosive components of biogas (e.g., H(2)S) and requires a 12 to 15 VDC power supply.

Biochemically enhanced hybrid anaerobic reactor

Abstract: A biochemically enhanced hybrid anaerobic reactor (BEHAR) system has been developed for treatment of high strength industrial wastewaters. The process is designed and operated based on specific criteria developed around critical biochemical and microbiological principles of the facultative and anaerobic microorganisms involved in anaerobic treatment. Biological kinetic relationships developed by the inventor for substrate removal, methane gas production, and biogas quality control as a function of the mass substrate loading rate are used for designing and operating the BEHAR process. A specific formulation of biological growth micronutrients has been developed for enhancing the anaerobic treatment process. Ferric chloride, one of the chemicals used as a micronutrient, is also utilized for sulfide toxicity control, biogas cleaning without scrubbing, and odor control. Magnesium hydroxide is also used as a micronutrient while offering the added benefits of sulfide toxicity control, biogas cleaning without scrubbing, odor control, and addition of alkalinity and buffering capacity to the BEHAR system, along with sodium toxicity control. Various combinations of ferric or ferrous salts and magnesium hydroxide are used to provide maximum and optimized bulk liquid sulfide control and biogas H 2 S control. Heavy metal toxicity control is also provided in problematic wastewaters by the addition of sulfates which are reduced to sulfides to precipitate heavy metals as insoluble metal sulfides. An understanding of these kinetic, microbiological and biochemical principles combined with a unique reactor design to enhance the practical application of these principles constitutes the BEHAR process.

Process for separate treatment and disposal of mixtures of solid and liquid, organic wastes

Abstract: A starting mixture of liquid and solid organic wastes that is susceptible to at least partial microbiological degradation, with formation of biogas, is treated by the following process. The mixture is mechanically separated into a first sludge phase with enriched dry substance and a first liquid phase containing dilute solids. The first liquid phase is subjected to anaerobic treatment leading to formation of biogas and to the development of a second sludge phase and a second liquid phase. The first sludge phase is subjected to aerobic treatment resulting in the formation of compost, fertilizer, or feed. At least part of the second sludge phase is recirculated into the starting mixture, thereby causing the formation of biogas in the starting mixture and facilitating decomposition of higher compounds contained in the starting mixture.

Processing waste materials for anaerobic digestion of the biogenic-organic constituents

Abstract: In a process of treating waste materials for an anaerobic digestion of the biogenic organic constituents of the garbage, particularly of the source separated organic waste, the wet waste, the residual waste and the commercial wastes, an easily dewaterable suspension of the biogenic organic substances is formed in a pretreating stage by a mechanical treatment including a selective dissolution and defibration of the biogenic organic substances. In dependence on the adjusted solids concentration the action of flow-dynamical forces is so controlled that the not biogenic organic substances, are not subjected to an appreciable disintegration before they are removed at the end of the pretreatment. Non-digestable substances are removed. The suspension is converted to biogas by an anaerobic digestion and to a compost-like residue. In the apparatus in accordance with the invention a gentle treatment of adhering solids in the crude waste is ensured in the pretreating stage in that the speed of the impeller 14 in the pulping vessel 13 is controlled in dependence on the solids concentration. This will also result in a distinct saving of energy and in a high efficiency.

Eyahiation of Manurial Value of Biogas spent Slurry Composted with Dry Mango Leaves, Wheat Straw and Rock Phosphate on wheat Crop

Abstract: An attempt has been made to handle efficiently the liquid biogas slurry and to improve its manurial value by absorbing the slurry in dry mango leaves or wheat straw, enriching it with Mussoorie rock phosphate and then composting for 20 and 40 days. The manures so prepared were evaluated by judging their influence on wheat yields, nutrient uptake by plant and post-harvest fertility status of the soil. Results show that 40-days. The composted Mussoorie rock phosphate-enriched biogas slurry absorbed in dry mango leaves was the best as manure for wheat.