In situ foulant–driven permanganate/peroxymonosulfate process for sustainable membrane fouling control and micropollutant removal

Abstract

Common natural organic matter, such as humic-like substances, proteins, and polysaccharides, cause the irreversible fouling of ultrafiltration (UF) membranes. This study proposes a novel strategy to utilize the common membrane foulants as valuable reagents to synchronously accomplish micropollutant removal and membrane fouling control via a foulant-driven permanganate/peroxymonosulfate (PM/PMS) (FDPP) process. Results show that membranes contaminated with bovine serum albumin (BSA), humic acid (HA), and alginate (SA) can be effectively cleaned within only 6 min with 99.9 %, 97.6 %, and 89.4 % restoration of the permeate flux, respectively. Notably, repeated experiments prove that the flux recovery ratio of membranes is >96 % after 20 recycle fouling-cleaning experiments. Meanwhile, ibuprofen removal rates of 4.9 × 10⁻² s⁻¹, 1.8 × 10⁻² s⁻¹, and 0.31 × 10⁻² s⁻¹ are achieved using the FDPP process with BSA, HA, and SA foulants during filtration, respectively, which were significantly higher than those achieved in the PM/PMS process without foulants. Mechanistic studies show that membrane foulants initiate the decomposition of [Mn^VII(OOSO₃)₄]⁻ via electron transfer. This generates a series of reactive species (Mn(V), Mn(VI), SO₄^•−, and ^•OH) that effectively oxidize irreversible foulants and micropollutants under spatial nanoconfinement. Moreover, BSA and HA are more beneficial for the generation of reactive species than SA in the FDPP process owing to their electron-rich property. FDPP cleaning consumes less energy and has higher efficiency than NaClO and NaOH cleaning. The proposed FDPP process has a high potential for synchronously removing micropollutants and controlling the irreversible fouling of UF membranes in practice