A combined photocatalytic slurry reactor-immersed membrane module system for advanced wastewater treatment

Slurry type photocatalytic reactors need subsequent particle separation to retain the catalyst in the system and allow the discharge of treated effluent. The immersed membrane module accomplished this without prior slurry settling step. Membrane feed pre-treatment with pH adjustment and particle charge neutralisation with aluminium chloride coagulant led to improved critical membrane fluxes, 15.25 L/m2 h and 19.05 L/m2 h, respectively. In each experiment MF/UF produced near zero turbidity permeate, completely retained the photocatalyst, and flocculation also improved the efficiency of DOC removal. Membrane fouling was controlled by particle aggregation rather than feed DOC levels, but the latter had significant impact on coagulant demand. The complete treatment train achieved up to 92% DOC reduction with 12 mg/L AlCl3 dosage using in-line coagulation conditions. The results show that in-line coagulation offers a simple yet effective means to improve the performance of slurry type photocatalytic-MF/UF hybrid systems for advanced water and wastewater treatment applications.