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 management 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 used as substrates under laboratory controlled conditions. Carbaryl, carbofuran and aldicarb were selected as the candidate substrates at concentrations of 10, 20 and 30 mg/L, believed to be representative of on-farm rinsate. Seed obtained from spent mushroom substrate (SMS) provided the microbial consortium for the experiments described. The experimental data indicated that the degradation rates of the three carbamate insecticides were described well by the Monod model using the net microorganisms growth rate with experimentally derived kinetic coefficients. The average values of k and Ks at 95 percent confidence levels were found to be 1.35 ± 0.36 day1 and 4.32 ± 2.33 mg/L for carbaryl, 0.424 ± 0.073 day−1 and 31.8 ± 4.83 mg/L for carbofuran and 0.077 ± 0.0132 day1 and 15.8 ± 4.22 mg/L for aldicarb, respectfully. Relatively, the magnitude of the kinetic coefficients indicate carbaryl and carbofuran were more readily biodegradable than aldicarb under the conditions imposed.