Abstract:The health risk assessment of municipal sludge recycling products is of guiding significance for theirs safe and standardized utilization. The sludges from a wastewater treatment plant was treated by pyrolysis and aerobic fermentation, respectively, and cytotoxicity and genotoxicity experiments were performed on the municipal sludge and its heat treatment residue using Chinese hamster ovary cells (CHO-K1) to assess the hazards and potential risks to typical mammalian cells. The experimental results show that the cytotoxicity and genotoxicity of sludge pyrolysis residues and aerobic fermentation residues are reduced compared to the original sludge samples. Compared with the original sludge sample, the results of RTCA cell proliferation test show that the growth inhibitory effect of CHO-K1 cells by sludge pyrolysis residue and aerobic fermentation residue on the growth of CHO-K1 cells is significantly weakened. The results of CCK-8 cytotoxicity experiment show that compared with the original sludge sample, the relative cell survival rates of sludge pyrolysis residue and aerobic fermentation residue increase by 161% and 137% respectively. The results of the Caspase 3 cell apoptosis protease activity experiment show that compared with the original sludge sample, the Caspase 3 apoptosis protease activity of CHO-K1 cells exposed to sludge pyrolysis residue and aerobic fermentation residue drop by 29.0% and 20.1% respectively. The comet experiment results show that compared with the original sludge sample, the tail lengths of sludge pyrolysis residue and aerobic fermentation residue shorten by 64.5% and 25.9% respectively. The tail moments drops by 78.4% and 28.1% respectively. The results of the study show that heat treatment techniques (pyrolysis treatment and aerobic fermentation treatment) can reduce the cytotoxicity and genetic toxicity of municipal sludge, and reduce the potential risks of municipal sludge to the ecological environmentand human health.