Generation of an Effective Internal Carbon Source for Denitrification through Thermal Hydrolysis of Pre-Precipitated Sludge

Abstract

Chemical pre-treatment with highly charged metal salts gives an effluent low in both organic substances and phosphorus. To use pre-precipitation as the first step in sewage treatment improves nitrification in the following biological step. The chemically precipitated sludge contains 75% or more of the organic substances in the raw sewage and can by a hydrolysis process be converted to readily degradable organic substances. This paper will review experiences from tests with thermal hydrolysis in a full scale plant as well as results from laboratory studies.