The possibility and applicability of coagulation-MBR hybrid system in reclamation of dairy wastewater

The significant improvements of membrane technology in reliability and cost effectiveness have increased the reuse probability and recycling extent of dairy wastewater. However, membrane fouling still remains a major bottleneck in wide application. In order to solve the problem, this paper investigated the possibility and applicability of coagulation-membrane bioreactor (MBR) hybrid system in reclaiming dairy wastewater. A comparative experiment based on the removal efficiencies and the membrane performance was designed to achieve the purpose. The results showed that polyaluminium chloride as the appropriate coagulant in coagulation process was effective for turbidity removal. Coagulation process played a very important role in stabilizing the effluent of MBR and the level of transmembrane pressure. MBR was a crucial process in turbidity and aluminum removal. MBR had the capability to resist shock loading and to maintain the high COD removal. Biological flocs in MBR could improve the fouling level of membrane. The hybrid system reduced 98% COD from the original and COD value of the wastewater came down to 8 mg/L. The combination of coagulation with MBR presents the possibility and applicability to reclaim effluent in dairy industries.

► We investigate the hybrid system of coagulation-MBR in reclaiming dairy wastewater.
► Coagulation stabilizes the MBR effluent and maintains the TMP level.
► MBR can resist shock loading and ensure effluent quality.
► Biological flocs in MBR could improve the fouling level of membrane.
► The hybrid system is feasible and applicable in dairy wastewater reclamation.