Removal of ibuprofen from wastewater: comparing biodegradation in conventional, membrane bioreactor, and biological nutrient removal treatment systems

Pharmaceuticals are continually being introduced into the influent of municipal wastewater treatment plants (WWTPs). Developing a better understanding of pharmaceutical removal mechanisms within the different treatment processes is vital in preventing downstream contamination of our water resources. In this study, ibuprofen, a popular over-the-counter pain reliever, was monitored by taking wastewater samples throughout the City of Guelph municipal WWTP. Greater than 95% of ibuprofen was found to be removed in the aeration tank, with aerobic biodegradation being the dominant mechanism. For comparison, first-order kinetics were used to quantify ibuprofen biodegradation in a conventional WWTP aeration tank and in a membrane bioreactor (MBR) pilot plant. The rate constants, k_biol, for the conventional tank and the MBR were determined to be (−6.8±3.3) L/g SS^*d and (−8.4±4.0) L/g SS^*d, respectively. These two rate constants were found to be statistically similar. Preliminary study of a biological nutrient removal pilot system also suggests that ibuprofen can be anaerobically degraded.