Recycled Reverse Osmosis Membranes Operated at Low-Pressure for Water Treatment and Point-of-Use Applications

Decentralized systems applied at the point-of-use (POU) could be an alternative for a safe drinking water supply in isolated regions and developing countries. Based on that, it was investigated the recycling of end-of-life reverse osmosis (EoL-RO) household modules as an alternative for groundwater treatment at the POU. The membranes were recycled through chemical oxidation using NaOCl (444,000 ppm.h) and the system was validated in a long-term operation, which technical efficiency was investigated in terms of its capacity to produce treated water in accordance with potability standards. The increase in permeability from 4.5 – 50.4 L/m²h.bar and decrease in salinity rejection from 99.4 to 11.6% suggests that the EoL-RO was effectively converted to UF. The recycled membrane still presented a lower resistance to filtration due to its porous characteristics (average pore size 0.04 ± 0.01 µm). In the perspective of POU application, the lower energy requirement for the recycled membranes compared to EoL-RO would represent advantages if compared to reverse osmosis household modules, more energy-demanding filters. Effective water treatment and a low fouling propensity were observed for long-term operation at the POU. The monitoring data demonstrates a steady permeate flux (21.2 ± 0.46 L/m²h). filtration resistance (6.37 ± 0.16x10¹⁴ 1/m), producing a total permeate volume (3,000 L) comparable with commercial filtration systems and in compliance with the 109 potability standards analyzed. From a broader perspective, the advantages of using recycled membranes could be extended to environmental aspects as it prevents the simple disposal of EoL-RO membranes in landfills