Removal of selected pharmaceuticals in an anaerobic membrane bioreactor (AnMBR) with/without powdered activated carbon (PAC)

•One-time addition of PAC enhanced long-term removal of Smx and Tcs in AnMBR.•PAC-enhanced biotransformation of Smx and Tcs was consistently observed.•PAC-induced abiotic transformation contributed to enhanced removal of Cbz and Dcf.•Tmp was consistently removed at efficiencies of around 94.2% with or without PAC.

The removal of five selected pharmaceutical compounds was investigated in a lab-scale anaerobic membrane bioreactor (AnMBR) treating synthetic sewage. Trimethoprim (Tmp) and sulfamethoxazole (Smx) were consistently removed at efficiencies of 94.2 ± 5.5%, and 67.8 ± 13.9%, respectively, while in contrast, only marginal removals of carbamazepine (Cbz) (0.3 ± 19.0%) and diclofenac (Dcf) (15.0 ± 7.2%) were achieved. Finally, three distinct stages of triclosan (Tcs) removal were observed: 82.3 ± 15.0% within the first 10 days; 54.4 ± 10.4% in the following 30 days; and 31.4 ± 12.6% in the last 30 days. Adsorption to the sludge was the major contributing factor for its initial high removal. When powdered activated carbon (PAC) was added to the AnMBR, the removal of all five pharmaceuticals improved, especially for Smx and Tcs, which showed removal efficiencies of 95.5 ± 4.6% and 93.2 ± 6.6%, respectively. Higher removals of Cbz (92.4 ± 5.3%) and Dcf (82.6 ± 11.1%) were also observed, but only within the initial 5 days of PAC addition, and enhancement in their biotransformation by PAC adsorption was determined to be the major contributing factor for these improved removals.

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