MODELING THE FATE OF CHLORINATED PHENOLS IN WASTE-WATER TREATMENT PLANTS

The behavior of 2-chlorophenol, 2,4,6-trichlorophenol and pentachlorop henol in activated sludge wastewater treatment plants was investigated at pilot scale. Batch sorption studies along with steady state and dy namic continuous flow experiments were performed to determine partitio ning between the liquid and solid phases and biodegradation rate coeff icients. A mechanistic mass balance based model was employed as a fram ework with which sorption and biodegradation coefficients were estimat ed by model fitting of experimental data for each compound. Pentachlor ophenol was adsorbed to the greatest extent and biodegraded the least with values for the sorption and biodegradation coefficients ranging f rom 0.6-9.6 L/g and 0.021-0.058 L/g.hr respectively. There was evidenc e of a dependence of biodegradation rate upon sludge age for pentachlo rophenol. The sorption and biodegradation coefficients for 2,4,6-trich lorophenol were estimated in the range 0.11-0.71 L/g and 0.041-0.042 L /g.hr respectively. 2-Chlorophenol was sorbed the least and biodegrade d to the greatest extent with sorption and biodegradation coefficients of 0.06 L/g and 0.23 L/g.hr respectively.