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Abstract: Treatment of pharmaceutical wastewater is a real challenge for wastewater engineers. In this study, a pilot-scale system including an external loop airlift membrane bioreactor (ELAMBR) was applied for treatment of a synthetic pharmaceutical wastewater. The performance of this system was evaluated in removal of acetaminophen as the main pollutant of a pharmaceutical wastewater. A conventional activated sludge (CAS process) laboratory system was used in parallel with this system to compare both systems in regard to their ability for acetaminophen removal. The performance of the ELAMBR system was monitored for approximately one month to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of acetaminophen. The removal efficiency was significantly higher in the ELAMBR system than the CAS process. 100% of the acetaminophen was removed after 2days in this system. The results also showed that initial concentration of acetaminophen, chemical oxygen demand (COD) and mixed liquid suspended solids (MLSS) are the most effective parameters in removal of a pollutant such as acetaminophen. This study demonstrates the usefulness of ELAMBR system for pharmaceutical wastewater treatment with the advantages such as: (i) simple operation and maintenance, (ii) efficient removal of pharmaceutical pollutant and COD and (iii) low-energy consumption. [Copyright &y& Elsevier]

Abstract: The effects of sludge viability on process performance and membrane fouling in a membrane bioreactor were investigated. A laboratory-scale submerged membrane bioreactor (SMBR) containing a flat-sheet microfiltration membrane was used at various percentages of living cellular flocs and dead cells. The effect of live to dead cells ratio on the extracellular polymeric substances (EPS) concentration was also studied. The proportion of dead cells affected the type of EPS in the mixed liquor as well as hydrophobicity of activated sludge. Tightly bound EPS (TB-EPS) mitigated membrane fouling, whereas loosely bound EPS (LB-EPS) caused severe membrane fouling. The results show that the content of TB-EPS and LB-EPS increases with dead cells portion. Furthermore, the ratio of TB-EPS to LB-EPS was presented as an important parameter in MBR performance. It was showed that this ratio is a good representative of flocculability of activated sludge and fouling intensity. Compared to the live cells, the dead cells had lower hydrophobicity and induced membrane fouling so that membrane permeability of the viable activated sludge was twice of the dead cell culture. The potential of zone settling velocity (ZSV) to be considered as a key parameter in MBR operation was also reported. [Copyright &y& Elsevier]

Highlights: [•] The impact of OLR on viability and activity of activated sludge sometimes is different. [•] SMP release in the bioreactor depends on the viability of activated sludge. [•] Novel method based on capacitance was introduced for viability of activated sludge. [•] Determination of activated sludge quality is important for efficient operation of MBR. [ABSTRACT FROM AUTHOR]