ON-SITE TREATMENT OF PESTICIDE WASTE AND RINSATE USING OZONE AND BIOLOGICALLY-ACTIVE SOIL

Pesticide waste and rinsate (PWR) obtained from a small farm was treated on site with ozone (18 h) and then circulated through a biologically active soil column (48 h). Concentrations of atrazine [2-chloro-4-(ethylamino)-6- (isopropylamino)-s-triazine], cyanazine [2-chloro-4-[(1-cyano-(1-methylethyl) amino]-6-(ethylamino)-s-triazine], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl)acetamide] were decreased from 17, 30, and 82 ppm, respectively, to less than 5 ppm. The concentration of the other major pesticide component, paraquat (1, 1′-dimethyl-4, 4′-bipyridinium dichloride), decreased from 40 to 22 ppm. Laboratory studies showed that the rate of ozonation of these mixed pesticides was not first order as was observed in pure solutions. Ozonolysis yielded products that were much more amenable to biological degradation than parent material. Bioassays of treated solutions indicated that herbicidal activity was eliminated. No evidence of mutagenic activity was indicated in Ames assays. © 1990, American Chemical Society. All rights reserved.