Process for the treatment of biological sludge generated by the purification of wastewater

摘要

A process is described for the treatment of biological sludge generated by the purification of industrial and civil wastewater which comprises the following steps: (a) acidification of the sludge to a pH ranging from 1.5 to 2.5 and thickening by means of sedimentation; (b) separation of the thickened sludge and a clarified product; (c) thermo-chemical treatment of the thickened sludge; (d) neutralization of the mixture obtained in step (c) to a pH ranging from 5.3 to 6.2; (e) separation of a solid fraction and a liquid fraction; (f) drying of the solid fraction obtained in step (e) and recovery of the liquid fraction. The solid fraction, characterized by a final content of dry product greater than 90%, can be used as an amending substance or fuel, whereas the liquid fraction, characterized by a high biodegradability can be used for the production of biogas or as a carbon and energy source for microorganisms.