Engineering PVC/TPU hybrid membranes for high-efficiency pharmaceutical wastewater treatment using MBR technology

Pharmaceutical industries discharge complex wastewaters rich in organic pollutants and microorganisms to the environment, which necessitate the engineering of high-performance and antibiofouling ultrafiltration (UF) membranes for long-term membrane bioreactor (MBR) operations. Nevertheless, the intrinsic hydrophobicity of conventional polyvinylchloride (PVC) membranes restricts their practical usage. In this study, a series of novel blended PVC/thermoplastic polyurethane (TPU) ultrafiltration membranes were fabricated via the non-solvent induced phase separation (NIPS) technique, aiming at treating actual pharmaceutical wastewater by an MBR system. Spectroscopic analyses (FTIR, XRD, DSC, and Raman) were conducted to confirm the molecular interactions and compatibility between PVC and TPU, while EDX and elemental mapping verified the existence of TPU-related elements and their homogeneous distribution. The inherent hydrophobicity of PVC was effectively overcome through TPU incorporation, resulting in a reduced contact angle from 84.9° to 69.4°. The incorporation of TPU significantly altered membrane morphology, increasing the porosity to 83.6% and exhibiting a nearly threefold enhancement in pure water flux (PWF), rising from 43.3 to 173.1 LMH, accompanied by enhanced equilibrium water content of 80.4%. During MBR operation, 96.7% COD removal, 41% reduction in irreversible fouling ratio (IFR), and a 60.7% flux recovery ratio (FRR) were achieved. The addition of TPU increased elongation up to 96.2%, abrasion resistance by 10%, and antibacterial properties by > 97%. Overall, the developed PVC/TPU blended UF membrane exhibits great potential for stable and efficient application in MBR systems for pharmaceutical wastewater treatment.