Analysis of a simple biodegradation process for the removal of volatile organic chemicals from wastewater based on a gas stripping principle

A simple biodegradation system consisting of an air stripping Yank and a bi oreactor was proposed for the treatment of volatile organic chemicals in wa stewater. Toluene was used as a model of volatile organic chemicals. An aqu eous solution of toluene and a basic mineral medium were placed in the air stripping tank and bioreactor, respectively. Toluene was stripped by supply ing compressed air into the stripping tank through a sparger, and the strip ped toluene was degraded by Pseudomonas putida mt-2 (ATCC 33015) in the bio reactor under aerobic conditions. The effect of the air stripping rate on b acterial growth was examined. A quantitative relationship was found between the air flow rate in the air stripping tank (Q(a)) and the stripping rate constant. During cultivation, the bacterial cells grew by utilizing toluene as the sole carbon source, and reached their maximum cell concentration (X -m) at the stationary phase. X-m showed a gradual decrease with increase in ea from 1.8 to 7.2 l/h, indicating a decrease in the rate of toluence degr adation with increasing Q(a). The X-m at Q(a)=1.8 l/h was the highest among the experiments under different values of Q(a), which was almost twice tha t at Q(a)=7.2 l/h. Mathematical analysis taking the growth kinetics and mas s transfer of toluene into consideration satisfactorily explained the syste m performance.