Papers and Reports

The behavior of 2-chlorophenol, 2,4,6-tricholorphenol and pentachlorophenol in activated sludge wastewater treatment plants was investigated at pilot scale. Batch sorption studies along with steady state and dynamic continuous flow experiments were performed to determine partiitioning between the liquid and solid phases and biodegradation rate coefficients. A mechanistic mass balance based model was employed as a framework with which sorption and biodegradation coefficients were estimated by model fitting of experimental data for each compound. Pentachlorophenol was adsorbed to the greatest extent and biodegraded the least with values for the sorption and biodegradation coefficients ranging from 0.6-9.6 L/g and 0.021-0.058 L/g – hr respectively. There was evidence of a dependence of biodegradation rate upon sludge age for pentachlorophenol. The sorption and biodegradation coefficients for 2, 4, 6-trichlorophenol were estimated in the range of 0.11-0.71 L/g and 0.041-0.042 L/g – hr respectively. 2-Chlorophenol was sorbed the least and biodegraded to the greatest extent with sorption and biodegradation coefficients of 0.06 L/g and 0.24 Lg – hr respectively. Increasing concerns about the emission of contaminants to the environment has led to a demand for knowledge about the behavior of these compounds in wastewater treatment plants. This requires an understanding of degradation rates and as well intermedia transport between the liquid, gas and solids states. More stringent regulations which have evolved as a result of these concerns have led regulators, designers and owners of wastewater treatment plants to require models predicting contaminant behavior, thereby allowing optimization of plant design and control. These models can be used to assess the impact of fluctuations in input concentration on effluent, sludge and offgas streams and can also be employed to establish limits on treatment plants influent loading based upon allowable effluent loadings.