Performance of the biosorptive activated sludge (BAS) as pre-treatment to UF for decentralized wastewater reuse

A biosorptive activated sludge (BAS) was operated at lab-scale with diluted and concentrated municipal wastewater to study the efficiency of removal of organics (particulate and soluble COD) and recovery of nutrients (TKN, ammonia, phosphorus). The system performed significantly better with concentrated wastewater, where COD removal efficiency was 80% at organic loading rates between 10 and 20 kg m−3 d−1. Supplementation of ferrous iron at 20 mg L−1, significantly improved both the removal of particulate, soluble COD and phosphorus. The effluent from the BAS was further treated using an ultrafiltration process with backwashing. The average permeate flux (at constant TMP = 0.3 bar) increased from 23 to 28 and 34 L m−2 h−1 when raw sewage, BAS without iron, and iron respectively were tested. The proposed technology is compact, efficient and suitable for decentralized water reuse, while the capital and operational expenses were calculated as 0.64 and 0.43 € m−3, respectively.