EVALUATION OF GENOTOXIC POTENCY ON SUBSTANCES CONTAINED IN NIGHT SOILAND ITS REDUCTION PERFORMANCE BY OZONATION

Bacterial assay which can detect the genotoxicity, induction of error- prone repair genes on DNA was applied to samples which were collected at a night soil treatment plant. The genotoxicity of each sample was m easured by using this bacterial assay, called the umu test. Strong gen otoxic potency was found in the sediments of raw night soil, that is, human feces. There are some substances which show toxicity to the DNA and are attributable to the baked foods or metabolites in human digest ive organs. These potencies could not be removed easily in the biologi cal decomposition process through survey of the treatment plant. It wa s quite clear that more effective reduction could be achieved by ozona tion at the treatment condition of about 1 mg O-3/mg C.