Anaerobic digester makes fertiliser and fuel gas - from organic wastes using heat agitation and liquid recirculation in fermentation zone

摘要

Anaerobic digester plant for organic liqs. and solids is claimed which comprises a thermally-insulated, gas-tight vessel divided into three zones, viz, loading and discharge zones sepd. from an intermediate fermenting zone by hydraulic trap seals; the interior of the vessel is equipped with a mechanical agitator and conveying means for solids, a circulation system extracting liq. from the bottom of the fermenting one to redistribute it at the top of the same zone and means of heating the vessel. The vessel is pref. egg-shaped in vertical cross-section, with sharply sloping sides near the bottom to prevent accumulation of deposits; the bottom itself is pref. flat for easy clearance of solids. Gases produced by fermentation are drawn off from the top of the central zone, enclosed between the hydraulic seals. Used for treatment of municipal and domestic organic wastes, dung, manure, stable-litter, etc. to produce a neutralised fertiliser with fuel gas by-prod. Allows homogeneous, rapid fermentation with no vessel dead-spaces, easy loading which does not interfere with full recovery of gas and simplified discharge of treated solids.