Milk processing wastewater treatment in a bioreactor followed by an antifouling O-carboxymethyl chitosan modified Fe3O4/PVDF ultrafiltration membrane

• The antifouling Fe3O4-OCMCS nanoparticles/PVDF UF membrane was prepared.
• The synthetic membrane was used in MBR for treating milk processing wastewater.
• The effects of MLSS and HRT on the MBR performance were conducted using RSM.
• Performance of the prepared UF membrane was comparable with commercial MF membrane.

In this study, a synthetic nanocomposite ultrafiltration membrane (prepared by blending polyvinylidene fluoride (PVDF) and hydrophilic O-carboxymethyl chitosan modified Fe3O4 (OCMCS-Fe3O4) nanoparticle) was applied in a bioreactor to treat milk processing wastewater (MPW). Experiments were carried out with two independent operating variables, mixed liquor suspended solids (MLSS) and hydraulic retention time (HRT). The region of exploration for the variables was taken as the area enclosed by MLSS (6000–14,000 mg/L) and HRT (8–44 h) boundaries. Throughout the experiments, high COD removal efficiency (92–99%) was obtained. The MLSS had an increasing impact on the removal efficiency of nitrogen, total phosphorous (TP), and flux. HRT also showed an increasing effect on the removal efficiency of nitrogen and flux while had a reverse impact on the TP removal efficiency. The optimal membrane performance was compared to commercial microfiltration (MF) membrane and the results showed that the blended membrane with modified nanoparticles leads to a high flux ultrafiltration membrane comparable with microfiltration while remaining its separation properties as much as UF membrane.

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