The impact of a Wastewater Treatment Works in Southern Gauteng, South Africa on efavirenz and nevirapine discharges into the aquatic environment

Although an order of magnitude lower nevirapine concentrations displayed the opposite behaviour and gradually increased through the various stages of purification in the WWTP. Minor fluctuations occurred but the concentrations of nevirapine were higher at the effluent (between 92 and 473 ng/L) than those entering the WWTP. No nevirapine was detected in the PST sludge. The increase in nevirapine concentrations are likely to be the result of the de-conjugation of the hydroxylated metabolites of nevirapine in the WWTP, its resistance to degradation and the lack of binding of the nevirapine to the PST sludge.