BIODEGRADATION OF MONO-CHLOROBENZENE IN A TRICKLE BED AIR BIOFILTER

Abstract

Volatile organic compounds (VOCs) are among the new class of air pollutants generated from a variety of industrial sources. The presence of VOCs in the atmosphere creates a number of problems for human health as well as environmental quality. Many . technologies are available for treating the VOCs. Among them biofiltration is the one which has attracted wide attention in the recent years. Biofiltration is based on biological destruction where VOCs present in the air streams are treated, without producing further more pollutants. Biofiltration is a cost effective air pollution control technology for volatile organic compounds. Biofiltration involves contacting of VOCs with microbial biofilms which are immobilized on porous support materials. Then the microorganisms in the biofilm degrade VOC into CO2, water and biomass. Biofiltration of Mono-Chlorobenzene (MCB) vapor from the air stream was evaluated using a biotrickling filter packed with coal. Mixed consortium of activated sludge was used as inoculum. The continuous performance of biotrickling filter for the Mono-Chlorobenzene removal was monitored at different gas concentrations, gas flow rates, and EBRT's. A maximum removal efficiency of 95.20 % was achieved for the inlet MCB concentration of 1.069 g/m3 and EBRT of 94.26 s. The effect of temperature and pH on the degradation of MCB in biotrickling filter was studied. The optimum temperature and pH were found to be 22°C-30°C and pH 7-7.7. The effect of starvation on the biotrickling filter was studied. After starvation, the biotrickling filter lost its ability to degrade MCB initially, but recovered very quickly within a short period of time. The kinetic constants such as half saturation constant and maximum reaction rate were determined for the degradation of MCB. A mathematical model was developed and the experimental results were compared with the theoretical values. The model showed that the degradation of MCB followed first order kinetics.