Digestion of sewage sludge to produce methane and fertiliser - passes incoming sludge through steam ejector:mixer to preheat to about 95 deg. C

摘要

Appts. for the digestion and thickening of sewage sludge obtd. from purificn. treatment plants. Upstream of the digestion chamber, incoming sludge is preheated by being passed through an ejector/mixer together with steam at high temp. and pressure, e.g. 185 deg.C and 10 bars. This results in sludge leaving the ejector/mixer at a temp. between 80 and 100 deg.C, pref. about 95 deg.C, which is sufficient to reduce the level of pathogens without completely sterilising the sludge. The digester is equipped with a mechanical agitator to homogenise the sludge. Digested material is discharged to a storage basin where the material is allowed to thicken. Used to produce methane and agricultural fertiliser by digestion and thickening of sewage sludge. The sludge is drawn from purificn. plants treating domestic, industrial or agricultural effluent. The controllable, high temp. injection of incoming sludge reduces the level of pathogens and enables the user to regulate fermentation rate.