The release and removal of sludge toxicity by different disintegration methods

Abstract The increasing production of toxic sludge becomes the limiting factor of sludge resource utilization. In this study, the source of sludge toxicity and the best way for toxic organic reduction was investigated. Four disintegration methods (freeze/thaw, ultrasonication, alkali-thermal hydrolysis and ozonation) were used to analyze the release of organic matter and sludge toxicity reduction. Ultrasonication (SCOD = 5120.4 ± 67.8 mg L−1) was the best way to break sludge and remove toxicity among four methods, which dissolution rate was more than 80%, and the total toxicity inhibition rate could be reduced to 64.3 ± 4.2%, significantly reducing the toxicity of sludge. Gel chromatography (GPC) showed that the disintegration could convert refractory macromolecular organics (MW > 10 kDa) into small molecular substances (MW