Efficiency evaluation of PTA wastewater treatment with the ultrasound/H2O2 process

摘要

In this study, we used the ultrasound/hydrogen peroxide (H_2O_2) process to treat the pure terephaltic acid (PTA) industrial wastewater. The BOD_5 and TOC of raw PTA wastewater were 13,200 and 6,390 mg/L, respectively. Several semiand non-volatile organics, such as benzoic acid, 4-methyl benzaldehyde, phenyl acetic acid, and 4-ethyl benzoic acid were detected in PTA wastewater by GCD (HP GCD 1800A). In the present paper, we discussed the effect of ultrasound/H_2O_2 process with various concentrations of H_2O_2 and pH values on mineralization and biodegradability of PTA wastewater. Minerali8zation of PTA wastewater was evaluated by the ratio of TOC removal, and biodegradability by real residual BOD_5 over theoretical residual BOD_5. The results show that the lower the initial pH value and the higher the concentration of H_2O_2, the higher ratio of mineralization was found. During the reaction time, the ORP value at pH 3 was greater than at pH 7 and 11. The pH value affected ORP value more significantly than H_2O_2 dosage in this work. The biodegradability increased with the amount of TOC removal by ultrasound/H_2O_2 process but decreased with the amount of TOC removal by ultrasound only. The optimum condition to pretreat PTA wastewater with ultrasound/H_2O_2 process before biological treatment was pH 3 and H_2O_2 200 mg/L. However, when ultrasound/H_2O_2 process was used as a sole treatment without biological treatment, the optimum pH value was also controlled at 3, but the concentration of H_2O_2 must increase upto 500 mg/L. Under such conditins, the ratio of mineralization was 70percent.