process for entwaessern of sewage sludge and system for implementation of the procedure.

摘要

PCT No. PCT/EP87/00641 Sec. 371 Date Apr. 13, 1990 Sec. 102(e) Date Apr. 13, 1990 PCT Filed Oct. 29, 1987 PCT Pub. No. WO88/03048 PCT Pub. Date May 5, 1988.Procedure for dewatering sewage sludge comprising the steps of subjecting pumpable sludge to chemical pretreatment with addition of a flocculation agent, pre-dewatering the chemically pretreated sludge by gravity filtration and conveying the pre-dewatered sludge by gravity, dewatering the pre-dewatered sludge by pressure filtration to form a sludge cake, crumbling the sludge cake to obtain sludge cake pieces, and drying the sludge cake pieces. After the dewatering step, so hard sludge cake is formed that after crumbling the sludge cake pieces are obtained which maintain their shape in accumulated consistency. A plant for the execution of the procedure is disclosed. The plant comprises a chemical pretreatment station having a receptacle for an addition agent, a dosing pump for filling the addition agent into a sludge pipe provided with a mixer, a pre-dewatering station having at least two pre-dehydration belts superposed in different layers, connected in zigzag series having shells for the reception of water, a sludge silo below the pre-dewatering station in which the sludge is conveyed by gravity, a press station arranged below the sludge silo having at least one filter press which may be loaded with pre-dehydrated sludge from the top, a crushing unit for the crumbling of the hard sludge cake to obtain sludge cake pieces with great surfaces, and a post-dewatering station consisting of drying belts.