A novel forward osmosis reactor assisted with microfiltration for deep thickening waste activated sludge: performance and implication

Waste activated sludge (WAS) treatment has gained growing interests for its increasingly capacity and high process cost. Sludge thickening is generally the first of WAS treatment. However, traditional approach was restrained by large footprint, low efficiency, tendency releasing phosphorus. Here, we reported a novel microfiltration (MF) membrane assisting forward osmosis (FO) (MF-FO) thickening. The MF-FO reactor achieved mixed liquor suspended solids (MLSS) concentration from approximately 7 to 50 g/L after 10-day operation. More importantly, effluent quality FO filtration superior with total organic carbon (TOC), ammonia nitrogen (NH4+-N), nitrate (NO3?-N) phosphorus (TP) 1.94 ± 0.46, 0.02 0.07, 4.55 1.59 0.24 0.26 mg/L, respectively. Additionally, integration MF successfully controlled salinity in range 1.6-3.1 mS/cm, which mitigated flux decline thus prolonged operating time. In this case, mainly due fouling. Furthermore, fouling layer on surface gel composed biofoulants foulants when MLSS less than 30 g/L, while it turned cake exceeded g/L. Results here demonstrated that promising technology excellent performance membrane.