Research On Fouling Behavior Of Nanofiltration Membranes In Strontium-bearing Mine Water Treatment Process And Desalination Performance

The treatment and reuse of mine water can effectively alleviate the shortage of water for production and living in mining areas,and is of practical significance to the construction of a resource-saving and environment-friendly Ningdong energy and chemical base.The fouling of nanofiltration membranes in the process of mine water treatment not only seriously affects the long-term stable operation of the process,but also greatly increases the economic operation costs.The influence of strontium salts on the fouling behaviour of nanofiltration membranes in mine water in Ningdong has not been elucidated yet.In this paper,the influence of the fouling behaviour and desalination performance of nanofiltration membranes in the membrane treatment process of mine water containing strontium is investigated in depth to further reveal the influence mechanism of the interaction between different inorganic salts and APAM on the fouling behaviour of nanofiltration membranes in the membrane treatment process of mine water containing strontium,and to explore the influence of scale inhibitors on the desalination performance of nanofiltration membranes.The effect of scale inhibitors on the desalination performance of nanofiltration membranes was also investigated.Firstly,an experimental setup for nanofiltration membrane treatment of mine water was set up to configure a simulated solution of strontium-containing mine water after softening.During the experiment,the changes in normalized membrane flux and permeate produced water quality were monitored in real time,and the results of contaminated membrane characterization were combined to conclude that the nanofiltration membrane fouling plugging behavior was mainly dominated by SrS04 salt scale,but the addition of APAM would alleviate the membrane fouling dominated by SrS04 inorganic salts,due to the fact that Na+,Ca2+,Sr2+,and the charge shielding effect reduces the repulsion between the membrane and APAM,and Ca2+and Sr2+ divalent cations produce loose clustered composite fouling by the "bridging" effect and ligand complexation between APAM-membrane and APAM-APAM.The presence of Sr2+ causes the composite fouling to adhere more readily to the contaminated membrane,leading to an increase in fouling resistance.However,the Ca2+ component leads to an increase in repulsive forces,an increase in energy barriers and a reduction in fouling blocking behaviour.Fouling of nanofiltration membranes affects membrane desalination performance.Fouling behaviour of nanofiltration membranes produced by two types of scale inhibitors,PASP and HEDP,residual in strontium-containing mine water is mainly dominated by PASP.PASP enhances the adhesion between membrane-fouling and fouling-fouling,and the coverage area of membrane surface composite fouling increases,but the presence of HEDP alleviates the membrane surface composite fouling dominated by PASP.The addition of scale inhibitor decreases the membrane retention of Na+,but increases the retention of Ca2+ and Sr2+ divalent cations.Comparison of the membrane cleaning results showed that the pure water flux of the contaminated membranes was lost due to residual fouling and irreversible structural changes on the membrane surface,and the contaminated membranes could not be fully restored to the original membrane index after the cleaning operation,and the recovery effect of pure water flux showed a gradual weakening trend as the number of cleaning times increased.The research results of this paper provide theoretical support for the mine water membrane treatment process to prevent scale and scale,and demonstrate practical significance in the reuse of mine water quality and cost reduction.