AEROBIC CARBAMATE BIOREMEDIATION AIDED BY COMPOST RESIDUALS FROM THE MUSHROOM INDUSTRY - LABORATORY STUDIES

Pesticide contamination of surface and groundwater resources has been a continuing concern of the agribusiness community. Inadequate managem ent practices, specifically involving the on-farm handling of rinsates , appear to be a major source of pesticide contamination. The goal of this paper is to present the experimental findings for the evaluation of the biodegradation rates of selected carbamate insecticides when us ed as substrates under laboratory controlled conditions. Carbaryl, car bofuran and aldicarb were selected as the candidate substrates at conc entrations of 10, 20 and 30 mg/L, believed to be representative of on- farm rinsate. Seed obtained from spent mushroom substrate (SMS) provid ed the microbial consortium for the experiments described. The experim ental data indicated that the degradation rates of the three carbamate insecticides were described well by the Monod model using the net mic roorganisms growth rate with experimentally derived kinetic coefficien ts. The average values of k and Ks at 95 percent confidence levels wer e found to be 1.35 +/- 0.36 day(-1) and 4.32 +/- 2.33 mg/L for carbary l, 0.424 +/- 0.073 day(-1) and 31.8 +/- 4.83 mg/L for carbofuran and 0 .077 +/- 0.0132 day(-1) and 15.8 +/- 4.22 mg/L for aldicarb, respectfu lly. Relatively, the magnitude of the kinetic coefficients indicate ca rbaryl and carbofuran were more readily biodegradable than aldicarb un der the conditions imposed.