Ibuprofen and diclofenac, two commonly used pharmaceuticals, were studied to evaluate the removal behavior of acid pharmaceuticals in constructed wetlands (CWs) with different flow types, vegetation and seasons. It was shown that flow types influenced the results significantly. The average removal efficiency of ibuprofen in horizontal subsurface flow (HSSF) and vertical subsurface flow (VSSF) CWs (69% and 60%, respectively) was significantly higher than that in surface flow (SF) CWs (26%). For diclofenac, SF CWs (58%) was significantly higher than HSSF and VSSF CWs (49% and 43%, respectively). In addition, the presence of plants improved the efficiency of ibuprofen, while it had no significant influence on the removal of diclofenac. Paired t-test found out that summer and autumn season variety had little impact on the removal. Furthermore, the removal of diclofenac and DO, as well as COD, showed very significant negative correlations. Opposite to diclofenac, the removal of ibuprofen had good positive correlations with dehydrogenase activities. The research indicated that aerobic biodegradation behavior mainly took place in ibuprofen, yet anaerobic biodegradation and photolysis behavior were expected for diclofenac.
Keywords: biodegradation; constructed wetlands; diclofenac; ibuprofen; photolysis.