Peroxymonosulfate based in situ chemical oxidation: An efficient strategy for mitigation of membrane fouling in real seawater reverse osmosis desalination

Persulfate based advanced oxidation processes (AOPs) is an emerging method to assist the pretreatment to prevent membrane fouling for seawater desalination. However, the present strategies which adopt activators (e. g., UV, heat, Fe) to generate kinds of free radicals, are energy-consuming and enhance the concerns of disinfection by-products (DBPs). Here, peroxymonosulfate (PMS) is adopted as a green, effective and economical pretreatment chemical for simultaneous microorganic pollutants degradation and microorganism inactivation in seawater reverse osmosis (SWRO) desalination without any external energy input. After adding into the seawater, 53% PMS could be activated by Cl- in situ to generate HClO at most with no other active species generated, which is verified by stoichiometric analysis and quenching experiments. Benefited from the residual PMS, not only could up to 89.6% of total organic carbon be removed in the real seawater, but also nearly 80% of DBPs could be degraded by simply adjusting pH from neutral to alkaline conditions. Meanwhile, all bacteria could be killed completely and hardly any regrowth appeared, which further proved the anti-fouling ability of the PMS/Cl- system. Consequently, the addition of PMS could maintain the flux for a long time in the practical SWRO application with significantly reducing the RO membrane fouling. Moreover, the operating cost of PMS is only 0.024 $/ton, which is comparable to NaClO. This study demonstrated the excellent performance of PMS in SWRO pretreatment, supplying a promising scheme in practical desalination processes.