Multi-ionic electrolytes and E.coli removal from wastewater using chitosan-based in-situ mediated thin film composite nanofiltration membrane

Abstract

This work presents the experimental investigation of flat sheet composite nanofiltration membrane synthesized with chitosan nanoparticles through interfacial polymerization of piperazine with trimesoyl chloride on polyethersulfone/sulfonated polysulfone substrates. The synthesized membrane was tested in wastewater treatment containing inorganic salts and E.Coli. Single binary electrolyte solution of KCl, MgCl₂, MgSO_4, and Na₂SO₄, ternary electrolyte solution, containing a combination of MgCl₂ and MgSO₄, KCl and MgCl₂ and quaternary electrolyte solution of KCl, MgCl_2, and MgSO₄ as feed were treated in crossflow membrane cell for the water flux and species rejection in the permeate under operating pressure up to 0.5 MPa. The rejection of Na¹⁺, K¹⁺, Mg²⁺, Cl^1-, and SO₄^2- was observed to be 81, 28, 87, 96, and 98%, respectively with an average water flux up to 214 ± 10 L m⁻².hr⁻¹ in the permeate for the binary electrolyte solution. Similarly, the rejection for K¹⁺, Mg²⁺, Cl^1- and SO₄^2- was noted to be 33, 94, 97, and 99%, respectively, for ternary electrolyte solution with an average water flux up to 211 ± 10 L m^-2.hr^-1. The quaternary ion system in the feed resulted in an average water flux up to 198 ± 12 L m⁻².hr⁻¹ with the rejection of K⁺, Mg⁺², Cl^- and SO₄^-2 as 35, 87, 96, and 99%, respectively. The model feed solution of E. coli after passing through the membrane achieved an E. coli rejection (99%) with water flux up to 220 L m^-2.hr^-1.

Keywords: Crossflow membrane; E. coli; Electrolytes; Interfacial polymerization; Nanofiltration membrane.