The intensification of sludge digestion by the disintegration of activated sludge and the thermal conditioning of digested sludge

Abstract

The study is focused on the anaerobic degradation of different disintegrated materials containing a cell lysate. The aerobic cell lysate was produced by a disintegration of the excess activated sludge by means of a lysate-thickening centrifuge, and the anaerobic cell lysate, by a rapid thermal treatment of anaerobic digested sludge. The improvement of both the methane yield and the biodegradability of thickened activated sludge is influenced by the quality of input excess activated sludge and the parameters and efficiency of the thickening centrifuge. The improvement of the methane yield was on average 11.5-31.3% depending on the sludge quality. The relation of the stimulation effect, the disintegration rate and the anaerobic sludge activity suggest that the efficiency of the disintegration will be probably higher in the more intensive digestion process. The rapid thermal treatment of digested sludge produced a material with an active anaerobic lysate. The stimulation effect of the anaerobic lysate caused an improvement of the methane yield of raw sludge in the range of 35-49% depending on the lysate amount. The rapid thermal reactor produced a relatively very active cell lysate from anaerobic bacteria; the heat energy of the lysate can be utilised in the digester heating system.