The operation of reverse osmosis system with CO2 as a scale inhibitor: A study on operational behavior and membrane morphology

Abstract

Fouling is one of the acute concerns during the application of reverse osmosis (RO) technology for wastewater reclamation. This study emphasizes the effectiveness of CO2 injection for scale inhibition on the surface of membranes during wastewater reclamation. The main objective of CO2 injection is to reduce pH of feed stream for avoiding inorganic scale precipitation. Two different experimental setups (lab- and pilot-scale) were installed and each was operated with four different RO modules including control (without any scale inhibitor), dosage of antiscalant, CO2 injection and simultaneous dosage of antiscalant and CO2 in an influent line. The pH of influent stream was reduced by CO2 purging at the level of 6 and 5. Data from operational setups, water analysis and morphological study of membrane from each module was used to establish comparative result. In comparison with other modules, the RO modules operated with CO2 were found successful to mitigate the inorganic scale formation on the surface of membrane. Furthermore, the RO modules operated with CO2 presented the successful restoration of system performance with clean-in-place.