Development of expanded polytetrafluoroethylene hollow fiber membranes for membrane Fenton oxidation in wastewater treatment.

The Fenton advanced oxidation technology is widely regarded as an effective solution for treating refractory industrial wastewater. However, a major challenge lies in the substantial generation of hazardous sludge. In this study, a novel membrane Fenton (MF) technique was developed, enabling efficient reuse of Fenton sludge and significantly reducing its discharge. To ensure stable and efficient performance under Fenton reaction conditions, expanded polytetrafluoroethylene hollow fiber membranes were fabricated by optimizing the stretching conditions. These membranes feature high porosity, low critical water yield pressure, high mechanical strength, and excellent oxidative resistance. The optimized membrane exhibited high water permeability (200.9 kg/m2h) and low effluent turbidity (1.31 NTU), making it suitable for Fenton sludge concentration. Subsequently, a sequential batch MF technique was designed to integrate the Fenton reaction, sludge concentration, and sludge reuse within a single reactor. The MF process reduced ferrous ion input and hazardous sludge production by 50 %, while achieving a comparable chemical oxygen demand removal efficiency (62.1-64.9 %) to the conventional Fenton process for metronidazole pharmaceutical wastewater. Furthermore, no irreversible membrane contamination occurred during eight continuous reaction batches. The prepared membranes also exhibited excellent chemical and mechanical stability, with no property changes detected after 40 days of immersion in the oxidant.