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

废物活性污泥（WAS）处理由于其容量不断增加和工艺成本较高而受到越来越多的关注。污泥增稠通常是WAS处理的第一步。然而，传统的污泥浓缩方法受到占地面积大，浓缩效率低和磷释放趋势的限制。在这里，我们报道了一种新型的微滤（MF）膜，可帮助正向渗透（FO）过程（MF-FO）用于污泥浓缩。在运行10天后，MF-FO反应器的混合液悬浮固体（MLSS）浓度达到了约7至50 g / L的污泥浓缩。更重要的是，FO过滤后的流出物质量与有机碳总量（TOC），氨氮（NH优越₄ ⁺ N），硝酸态氮（NO ₃ ^--N）和总磷（TP）分别为1.94±0.46、0.02±0.07、4.55±1.59和0.24±0.26 mg / L。此外，MF膜的集成成功地将MF-FO反应器的盐度控制在1.6-3.1 mS / cm的低范围内，这减轻了FO膜的通量下降，从而延长了运行时间。在这种情况下，MF-FO反应器中FO膜的通量下降主要是由于膜结垢。另外，FO膜表面上的污垢层是当MLSS浓度低于30g / L时主要由生物污垢剂和有机污垢剂组成的凝胶层，而当MLSS浓度超过30g / L时则变成滤饼层。