Water Recycling from Greywater of Shiraz University Dormitory by Membrane Bioreactor (MBR)

Interest in wastewater recycling as an alternative source has grown as a result of increased water demand, water shortage due to population increase, low rainfall, and economic and environmental issues. Water recycling from greywater can serve as a sustainable solution for water demands. Nowadays, membrane bioreactor systems have significantly improved treatment performance and have been widely used in water reuse and reclamation. However, optimization of the MBR system in greywater treatment has received less attention. In this context, an experimental investigation of the MBR for greywater reuse was considered to identify the optimal hydraulic retention time of the MBR system. The lab-scale MBR consisted of a bioreactor with a net volume of 10 L, containing one submerged polypropylene hollow fiber membrane module with an area of 0.2 m2. The lab-scale MBR was fed with greywater collected from a dormitory of Shiraz University and operated for 160 days. Four HRTs (3, 5, 7 and 9 h) were tested to investigate the performance of the MBR system on the removal of total ammonia nitrogen, organic matter, turbidity, and total suspended solid. The results showed that the MBR system could remove more than 95% of COD, 99.5% of BOD5, 99% TAN, and 99.2% of TSS from greywater. The COD, BOD5, TSS effluents, and turbidity were below 10.5 mg/L, 0.4 mg/L, 0.6 mg/L, and 0.3 NTU, respectively. The results also showed that the optimal HRT of the MBR system for greywater treatment was 3 h. In conclusion, the MBR system with optimal HRT of 3 h is highly efficient for greywater treatment and it could produce sustainable water for non-potable reuse such as toilet flushing reuse in terms of chemical–physical quality parameters.