Polyepoxysuccinate as a green scale inhibitor for Ba2+ to mitigate irreversible blockage of reverse osmosis membrane during treating landfill leachate

Barium ion (Ba²⁺) in landfill leachate is easy to combine with SO₄²⁻ introduced in acidification treatment stage to generate BaSO₄ precipitate, which causes irreversible blockage of reverse osmosis (RO) membrane in the post-treatment stage. To maintain the stable operation of RO membrane system treating landfill leachate, this study systematically investigated polyepoxysuccinate (PESA) as a green scale inhibitor for Ba²⁺ to mitigate irreversible blockage of RO membrane. The feasibility experiments showed that PESA (0.60 mg/L) could make the scale inhibition rate (SIR) close to 100 % for Ba²⁺ (10.00 mg/L). Adding PESA before the acidification treatment of landfill leachate remarkably improved the scale inhibition effect for Ba²⁺. The coexisting Ca²⁺ and Mg²⁺ made PESA dosage slightly increase to achieve high SIR for Ba²⁺, but the common scale inhibitor 1-hydroxyethylidene-sodium bisphosphonate (HEDP) for Ca²⁺ and Mg²⁺ showed little interference. The application experiments showed that the PESA dosage of 1.00 mg/L achieved an SIR of close to 70 % for the real landfill leachate with Ba²⁺ of 5.09 mg/L. Furthermore, PESA was proved to effectively mitigate the irreversible blockage of RO membrane treating real landfill leachate via inhibiting Ba²⁺ scaling. The analyses of X-ray diffraction, elemental composition and Fourier transform infrared spectroscopy showed that the scale inhibition mechanism of PESA for Ba²⁺ includes mainly chelating solubilization and lattice distortion. Accordingly, PESA showed a good prospect in scale inhibition for Ba²⁺ to mitigate irreversible blockage of RO membrane during treating landfill leachate.