| 摘要 |
PURPOSE:To increase the rate of digestion at a high load and to increase the output of gas by concentrating the excess sludge formed in the activated-sludge treatment of sewage to 1-6wt%, and digesting at about 53 deg.C with anaerobic microorganisms. CONSTITUTION:Excess sludge is maintained at 53+ or -0.5 deg.C in a digestion tank 20, and retained in the tank for several ten days under agitation by an agitator at a load of organic materials of 1.5-3.5kg/m<2>/day and digested. The organic materials are decomposed by anaerobic microorganisms, and gaseous methane contg. about 65vol% methane and having about 5,600kcal/Nm<3> net heating value is generated about ten times the gas output and stored in a gas tank 11. The gaseous methane is used as a fuel for a hot-water boiler 19 and also used for other purposes. The digested sludge in the digestion tank 20 is drawn out from the bottom of the tank through a sludge pipe 9, stored in a sludge storage vessel 21, and then sent to a dehydration stage.
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