Polymerized titanium salts for municipal wastewater preliminary treatment followed by further purification via crossflow filtration for water reuse

摘要

Research concerning polymerized titanium salts for preliminary treatment of municipal wastewater remains limited. We proposed the pre-coagulation of municipal wastewater with polymerized titanium based coagulants, followed by direct crossflow ultrafiltration for water reuse by avoiding biological treatment. Compared with polymerized aluminum chloride (PAC), polymerized ferric sulfate (PFS) and polymerized titanium sulfate (PTS), the polymerized titanium chloride (PTC) achieved higher coagulation efficiency, with chemical oxygen demand (COD) and total phosphorus (TP) removal reached 80.5% and 99.1%, respectively. Besides, PTC produced larger flocs (median equivalent diameter of 1408.1 tim) with better settling ability (flocs sedimentation in 1 min), higher shear resistance (strength factor reached 95.87%) and stronger re-aggregation capability (recover factor of 225.13%). The subsequent direct crossflow ultrafiltration of primary settled municipal wastewater could achieve complete suspended solids and P removal, being accompanied by additional 10-15% of organics removal. Specifically, ultrafiltration of PTC effluent obtained larger permeate flux up to 499.5 L M-211-1 and the reused water having higher quality (COD removal of 90.4%). Current study demonstrated the feasibility and superiority of utilizing polymerized titanium salts (especially PTC) for preliminary treatment of municipal wastewater. The resultant high-quality effluent through direct ultrafiltration provides alternative schemes for the demanding reclaimed wastewater reuse.