Anaerobic DDT biotransformation: Enhancement by application of surfactants and low oxidation reduction potential

Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the production of DDD (1,1-dichloro-2,2-bis(p-chlorophenyl) ethane) upon removal of one aliphatic chlorine. The DDT transformation rate increased with the addition of the nonionic surfactants Triton X-114 or Brij 35. The addition of either surfactant or reducing agents did not significantly extend the DDT transformation. Addition of both surfactant and reducing agents extended DDT transformation by reducing the accumulation of DDD and increasing the accumulation of less chlorinated products. It is important to minimize the accumulation of DDD because it is a regulated pesticide and is recalcitrant to aerobic transformation. Controlled experiments revealed that the transformation of DDT requires microbial culture, but the culture need not be biologically active. Transformation results are presented for aqueous and soil phase contamination.