BIOMINERALIZATION OF ATRAZINE OZONATION PRODUCTS - APPLICATION TO THEDEVELOPMENT OF A PESTICIDE WASTE-DISPOSAL SYSTEM

Development of remediation techniques for unusable pesticide wastes ha s led to a binary scheme involving ozonation followed by biomineraliza tion of the resultant oxidized pesticides. Preliminary field tests of this technique indicated that the s-triazines were somewhat, more reca lcitrant than the other pesticides present. Further experiments identi fied the final ozonation products of atrazine, the most widely used s- triazine, as 4-acetamido-6-amino-2-chloro-s-triazine (CDAT) and chloro diamino-s-triazine (CAAT). These compounds can be utilized by microorg anisms only as nitrogen sources; however, 1 % concentrations of ammoni a fertilizers are not uncommon in pesticide waste. Therefore, the orga nism should prefer an organic nitrogen source and tolerate high ammoni a concentrations. A Klebsiella terragena (strain DRS-I) was observed t o degrade CAAT in the presence of high ammonia concentrations (0.8 M) with the addition of a carbon source (corn syrup), in contrast to a kn own s-triazine-degrading organism which could not. Nearly complete min eralization of CAAT to CO2 by DRS-1 was demonstrated using CAAT-U-ring -C-14. Bench-scale reactors indicated that continuous-flow or fixed-fi lm reactors would support growth of DRS-1 cultures and CAAT degradatio n.