Biodegradability of pesticides in water by microbes in activated sludge, soil and sediment.

A relatively simple, aerobic and anaerobic biodegradation test method for pesticides is proposed. The method consists of the inoculation of the test substance to a substrate of non-acclimated microbes in activated sludge, field soil and river sediment in a stirred flask. This method was applied to the evaluation for biodegradability of twelve pesticides. The biodegradation rate constants obtained showed a parabolic correlation with the 1-octanol-water partition coefficients of the pesticides and a linear one with their alkaline hydrolysis rate constants. Therefore, the biodegradability of pesticides can be predicted by these two parameters.