Removal of bisphenol A and 4-n-nonylphenol coupled to nitrate reduction using acclimated activated sludge under anaerobic conditions

摘要

BACKGROUND: Bisphenol A (BPA) and 4-n-nonylphenol (4-n-NP) are of significant research interest due to their extensive use and toxicological properties. Batch experiments were conducted to investigate the sorption and degradation behavior of BPA and 4-n-NP using acclimated activated sludge either under anoxic conditions in the presence of nitrate or under anaerobic conditions in the absence of nitrate. RESULTS: Sorption of BPA and 4-n-NP on sludge was a spontaneous physical and exothermic process; partitioning played a dominant role. The values of partitioning coefficients of BPA and 4-n-NP under different redox conditions follow the order anaerobic>anoxic>aerobic. While BPA was degraded under both anaerobic and anoxic conditions, 4-n-NP was degraded only under anoxic conditions. The degradation rate of BPA under anoxic conditions is much greater than that under anaerobic conditions, and they are much greater than the degradation rate of 4-n-NP under anoxic conditions. Mixed liquor suspended solid and temperature influenced their sorption and degradation. A suitable COD/NO_3~--N ratio was 15 for both BPA or 4-n-NP elimination, and nitrate reduction. CONCLUSION: Effective degradation of BPA and 4-n-NP under nitrate reducing conditions provides an alternative removal method for refractory endocrine disrupting compounds in wastewater treatment plants.