USE OF POLYTETRAFLUOROETHYLENE RASCHIG RINGS AS A CARRIER IN MALATHION BIODEGRADATION

Abstract

Untreated wastewater potentially contains a variety of chemical constituents such as pesticides, which are hazardous to human health, and the environment. Malathion S-[1, 2- di(ethoxycarbonyl) ethyl] dimethyl phosphorothiolothionate; CAS No 121-75-5; C10 H19 O6 PS2] is one of the most widely used organophosphate insecticides throughout the world because of its efficacious control of insects. Several studies have examined the degradation of malathion by microbes and most of these studies were carried out using pure cultures. Little information is available concerning degradation of malathion by activated sludge culture. The purpose of this investigation was to study the biodegradation of malathion using indigenous activated sludge culture. In addition, no studies have examined the biological degradation of malathion using immobilized microbial cells or biofilm reactors. Therefore, the performances of a laboratory scale reactor (Packed Bed Reactor) treating malathion using polytetrafluoroethylene raschig rings as carrier for cell immobilization were investigated. The results showed that the degradation capacity of the reactor packed with polytetrafluoroethylene raschig rings was higher than the performance obtained with the batch reactor. Malathion removal efficiency observed for the carrier tested was affected by the flow rates. In fact, the maximum degradation rates of malathion by activated sludge culture were found to be 67%, 77.5%, 87.5%, and 94% for flow rate values of 2, 1.5, 0.6, and 0.2 cm3/min, respectively.