EFFECTS OF TEMPERATURE ON CHLOROPHENOL BIODEGRADATION KINETICS IN FLUIDIZED-BED REACTORS WITH DIFFERENT BIOMASS CARRIERS

Groundwater contaminants including 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), and pentachlorophenol (PCP) were mineralized in three aerobic fluidized-bed reactors (FBRs) employing sand, volcanite, and diatomaceous earth as biomass carriers. The effect of temperature on chlorophenol degradation kinetics was studied in FBR batch tests at temperatures ranging from 4 to 16.5°C. TCP and TeCP degradation was modeled using the Michaelis-Menten kinetics. Specific maximum degradation rates for TCP and TeCP varied with temperature from 0.46 × 10 −3 to 31 × 10 −3 mg mgVS −1 h −1 and K s varied from zero to 7.1 mg l −1. Degradation of PCP was affected by the presence of TCP and TeCP and followed competitive inhibition kinetics. Specific degradation rates for PCP degradation varied with temperature from 0.24 × 10 −3 to 1.7 × 10 −3 mg mgVS −1 h −1 and were always lower than for other chlorophenols. The Arrhenius equation described the temperature effects on biodegradation of chlorophenols. The activation energies (kJ mol −1) for TCP and TeCP varied from 126 to 194, and for PCP from 59 to 130. In the studied temperature range, a 10°C decrease in temperature generally resulted in over seven times slower degradation rates. The volcanite reactor had the highest and the sand reactor the lowest biomass accumulation. © 1998 Elsevier Science Ltd. All rights reserved