BIODEGRADATION KINETICS OF CHLOROPHENOLS IN IMMOBILIZED-CELL REACTORSUSING A WHITE-ROT FUNGUS ON WOOD CHIPS

This research investigated the ability of wood-chip reactors seeded wi th a white-rot fungus (Phanerochaete chrysosporium) to degrade hazardo us substances (4-chlorophenol [4-CP] and 2,4-dichlorophenol [2,4-DCP]) . Batch-reactor tests were conducted using 4-CP as a model compound to evaluate the effect of carbon and nitrogen deficiencies on the abilit y of white-rot fungus immobilized on wood chips to degrade 4-CP. The w hite-rot fungus degraded 4-CP (71.1 to 83.0%) under all tested conditi ons including the non-glucose and non-nitrogen conditions. However, th ere are differences in the degradation percentage of 4-CP using the di fferent growing conditions. The degradation of 4-CP occurs to the grea test extent in the non-glucose/with-nitrogen condition (15.38 ppm/h . g of specific biodegradation rate). Continuous-flow packed-bed reactor tests are conducted using 2,4-DCP as a model compound to evaluate the inhibition effect of 2,4-DCP on the biodegradation enzymes in wood-ch ip reactor systems, and the inhibition effects seem to be present. The inhibition kinetics of 2,4-DCP are successfully modeled with the mass -balance equation of plug-flow reactors and a substrate-inhibition equ ation for the reaction rate, yielding an inhibition constant, K-i of 6 9.8 ppm and a maximum 2,4-DCP concentration, [S](max), of 48.9 ppm at the highest reaction rate. The importance of these results is that the substrate-inhibition model can be used to explain the inhibition effe ct of 2,4-DCP on the biodegradation enzymes in this wood-chip reactor system. This study points to the potential of continuous-flow reactors using wood chips as a carbon source to degrade toxic chemicals with h igh-degradation efficiency.