Bio-gas generation from household refuse and clarifying sludge - by mixing and grinding, swelling, flotation, water-extn., anaerobic putrefaction and composting

摘要

Bio-gas generation comprises comminuting and mixing untreated household refuse with non-dehydrated clarifying sludge by a 2- or multi-step grinding process, pref using a 2- or multi- compartment ball mill. The sludge obtd is swelled for several hrs. All sludge components incapable of rotting, including plastics, are sepd by one or more flotation processes. The solids content of the remaining sludge is increased to 40% by mechanical water-extn. The dehydrated sludge mixt is made to undergo a controlled anaerobic putrefaction at 30-35 deg C. Anaerobic putrefaction is broken off on reaching max combustible bio-gas yield. A controlled aerobic composting process is then applied to increase hygiene and form humus. The heat required for anaerobic putrefaction is abstracted from the composting process. The compost can be used as soil-improver. The sludge can be used without processing and the refuse requires no preliminary sorting.