The effects of chlorine dioxide and chlorine
disinfections on the genotoxicity of different biologically
treated sewage wastewater samples were studied by umu-test.
The experiment results showed that when chlorine dioxide
dosage was increased from 0 to 30 mg/L, the genotoxicity of
wastewater first decreased rapidly and then tended to be
stable, while when the chlorine dosage was increased from 0
to 30 mg/L, the genotoxicity of wastewater changed diver sely
for different samples. It was then found that ammonia nitrogen
did not affect the change of genotoxicity during chlorine
dioxide disinfection of wastewater, while it greatly affected
the change of genotoxicity during chlorine disin fection of
wastewater. When the concentration of ammonia nitrogen
was low (< 10–20 mg/L), the genotoxicity of wastewater
decreased after chlorine disinfection, and when the concentration
of ammonia nitrogen was high (> 10–20 mg/L),
the genotoxicity of wastewater increased after chlorine
disinfection.