Cyclen-based polyamide thin film composite nanofiltration membranes for humic substances/salts separation from landfill leachate MBR effluent

Nanofiltration (NF) and reverse osmosis (RO) treatment of landfill leachate from MBR effluent will produce refractory leachate concentrates containing high concentrations of humic substances and salts. A NF membrane with the ability to separate organic substances and inorganic salts to prevent the accumulation of humic substances and salts during treatment were prepared through interfacial polymerization (IP), utilizing 1,4,7,10-tetraazacyclododecane (Cyclen) with a large spatial structure as the monomer of aqueous-phase and Trimesoyl chloride (TMC) as the oil-phase monomer. Subsequently, Cyclen/TMC membranes were employed to treat landfill leachate derived from the MBR effluent to separate humic substances and inorganic salts. The resulting Cyclen/TMC membranes exhibited good performance and pure-water permeance (P = 31.73 L m -2 h -1 bar -1 ), low salt rejection (R NaCl = 10.15%, R MgCl2 = 19.60%), and a molecular weight cutoff of 269 g/mol. Moreover, they showed separation properties for humic substances and inorganic salts (R humic substances = 96.36%, R Salts = 9.65%) in landfill leachate MBR effluent. Antifouling and long-term stability tests showed the magnificent operating stability of the Cyclen/TMC membranes. The appropriate negatively charged surface of the membrane contributes to its effective antifouling capability and long-term stability, surpassing those of the NF270 commercial membrane. Cyclen/TMC membranes have the potential for application in landfill leachate treatment, which will promote the advancement of landfill leachate resource management.