THE MEASURE OF EXTRA OXYGEN DEMAND FOR THE COMETABOLIC TCE REMOVAL BY A RESPIROMETER

摘要

This study focused on the measure of the extra oxygen demand for the cometabolic trichloroethylene (TCE) removal by phenol-degrading cells. A respiro meter was used to measure the difference in oxygen consumptions between the phenol removal and both phenol and cometabolic TCE removals. The theoretical equation suggests that the oxygen consumption for phenol biodegradation is 1.65 mg-02/mg-phenol. The oxygen consumptions measured by the respirometer were 1.64 and 1.61 mg-O2/mg-phenol for a duplicate test at an initial phenol concentration of 20 mg/L. The experimental values were very close to the calculated theoretical value (1.65 mg-O_2/mg-phenol). When phenol was used as the substrate to cometabolically remove TCE at initial concentrations of 500 or 1200 μg/L, TCE concentrations decreased to 10 and 403 μg/L after 27 hours of operation, respectively. With the cometabolic TCE removal, the extra oxygen consumptions were 0.2 and 0.4 mg for initial TCE concentrations at 500 and 1200 mg/L, respectively. According to the extra oxygen demand and the TCE removal, the oxygen demands for the cometabolic TCE removal were 0.41 and 0.51 mg-O_2/mg-TCE at initial TCE concentrations of 500 and 1200 μg/L, respectively. The experimental result (average 0.46) was close to the theoretical value (0.37 mg-O_2/mg-TCE) calculated from a postulated equation.