THE EFFECT OF A pH-ADJUSTMENT COMBINED WITH THERMAL PRE-TREATMENT ON THE DEWATERlNG OF SEWAGE SLUDGE
It is invesdgated whether heat-treatment combined with pH-adjustmenr improves the dewatering characteristics of sewage sludge. The treatment is done in order to secure hygienisated sludge by which the manuring and earth-improving effect of the sludge can be utilized in agriculture without any precautions in the case of a fullscale sewage plant. Furthermore fihrate from the dewatering is analysed for its quality as a carbon source for biological processes in wasre water treatment. To characterize the degree of dewatering the following factors are investigated: necessary polymer dosage, filterability and the content of dry solids in the sludge after dewarering. The analysis of the filtrate includes COD, N and Oxygen-Uprake-Rate (OUR).