Analysis of a Simple Biodegradation Process for the Removal ofudVolatile Organic Chemicals from Wastewater Based on audGas Stripping Principle

摘要

A simple biodegradation system consisting of an air stripping tank and a bioreactor was proposed for the treatment of volatile organic chemicals in wastewater. Toluene was used as a model of volatile organic chemicals. An aqueous solution of toluene and a basic mineral medium were placed in the air stripping tank and bioreactor, respectively. Toluene was stripped by supplying compressed air into the stripping tank through a sparger, and the stripped toluene was degraded by Pseudomonasputida mt-2 (ATCC 33015) in the bioreactor under aerobic conditions. The effect of the air stripping rate on bacterial growth was examined. A quantitative relationship was found between the air flow rate in the air stripping tank (Q,,) 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,) at the stationary phase. X, showed a gradual decrease with increase in Q,, from 1.8 to 7.2 Z/h, indicating a decrease in the rate of toluene degradation with increasing Q.. The X,,, at Q.=1.8 Z/h was the highest among the experiments under different values of Qp, which was almost twice that at Q,=7.2 Z/h. Mathematical analysis taking the growth kinetics and mass transfer of toluene into consideration satisfactorily explained the system performance.