Performance of an anaerobic membrane bioreactor for pharmaceutical wastewater treatment

•Wastewater from pharmaceutical industry can be treated by anaerobic MBR technology.•Varying wastewater composition had negative influence on the treatment efficiency.•Addition of waste organic solvents caused inhibition of the anaerobic degradation.•Dichloromethane exhibited the strongest inhibitory effect on anaerobic degradation.•Changes in the biocenosis reflected the substrate pattern and inhibition events.

Anaerobic treatment of wastewater and waste organic solvents originating from the pharmaceutical and chemical industries was tested in a pilot anaerobic membrane bioreactor, which was operated for 580 days under different operational conditions. The goal was to test the long-term treatment efficiency and identify inhibitory factors. The highest COD removal of up to 97% was observed when the influent concentration was increased by the addition of methanol (up to 25 g L−1 as COD). Varying and generally lower COD removal efficiency (around 78%) was observed when the anaerobic membrane bioreactor was operated with incoming pharmaceutical wastewater as sole carbon source. The addition of waste organic solvents (>2.5 g L−1 as COD) to the influent led to low COD removal efficiency or even to the breakdown of anaerobic digestion. Changes in the anaerobic population (e.g., proliferation of the genus Methanosarcina) resulting from the composition of influent were observed.