Evaluation of a soil-based pesticide wastewater disposal system using a combination of chemical parameters and microbial biomarker techniques

Non-point source pollution from agricultural pesticides is a growing problem in surface and groundwater contamination. Even though an operator may follow best management practices during application, there remains the residual pesticide contaminated wastewater (tank rinsates).

Mixed waste streams of commonly used East Tennessee herbiddes at various concentrations were tested in soil columns which simulated a Soil Bed Bioreactor, and then repeated with the addition two other insecticides. Pesticide dissipation, soil chemistry, and microbial community response were of prime interest.

Results indicate that pesticide dissipation behavior in the bioreactor is similar to that in the field, and that of the seven pesticides analyzed in this experiment, six significantly dissipated at low and moderate concentrations within 30 days. As pesticide concentration in the bioreactor increased the microbial community structure shifted to one that was resistant, a shift that may ultimately be involved in detoxification.

These data demonstrate and validate the utility of this technology to concentrate and dissipate pesticide rinsates, and show that these methods could become an important tool for farmers and custom applicators.