Strategy for flux enhancement in biofilm ceramic membrane bioreactor applying prepolymerized and non-prepolymerized inorganic coagulants
Peer reviewed, Journal article
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Considering new legislative and economic restrictions caused by the water crisis, this work focuses on a more efﬁcient wastewater treatment process, which combines biological treatment in a moving bed bioﬁlm system with a membrane bioreactor (BF-MBR) and coagulation, particularly addressing fouling alleviation in the separation stage. The study justiﬁes the positive impact of coagulantdosinginBF-MBRregardingmembraneﬂuxandfoulingrate. Statisticaltechniquesconnect the results of coagulation and membrane separation experiments with properties of mixed liquor, obtainedafterbiotreatmentintherepresentativepilotplantandcharacteristicsofprepolymerizedand non-prepolymerized inorganic coagulants. Research results substantiate the need for a pH-controlled coagulation of mixed liquor in BF-MBR depending on coagulant type, which inﬂuences charge, hydrophobicity and size of ﬂocs and organic content of the system. It is suggested, that the adsorption/charge neutralization mechanism dominates in ﬂux enhancement in BF-MBR, giving the best results in the case of prepolymerized aluminium coagulants. Together with high quality of permeate, the application of prepolymerized aluminium chloride of medium basicity entails a tenfold increase in ﬁltration time of the membrane separation cycle and increases net membrane ﬂux by 30–56%. The results of the study are practically signiﬁcant for the development of an automated controlsystemforBF-MBR,optimizingtreatmentratestogetherwithmembraneseparationefﬁciency.