EFFECT OF ACTIVATED-SLUDGE MICROPARTICLES ON PESTICIDE PARTITIONING BEHAVIOR

Solutions prepared by suspending freeze-dried sludge in water were fou nd to contain aggregated particles of about 1000-nm size and substanti al concentrations of surfactants. The microparticles sorbed significan t amounts of the organophosphorus (OF) pesticide diazinon, causing low recoveries and a decrease in observed partition coefficients with an increase in the suspended sludge concentration. The microparticles cou ld be removed by prewashing the sludge, by filtration, or by passing t he solution through a C-18 cartridge, which effectively acted as a fil ter. In contrast to diazinon, the recovery of the more polar OP propet amphos was excellent. Microparticles were not significant in muffled s ludge obtained from the same source but were significant in three wast e streams at a sewage treatment plant, including the final effluent. T his could pose problems when predicting the extent of pesticide remova l during sewage treatment.