Study On The Preparation Of Cement Hollow Fiber Membrane And The Treatment Performance Of Landfill Leachate

Landfill leachate is defined as a type of high-concentration waste water produced by eluviation of the free water contained in the garbage,natural precipitation,decomposition water of organic matter during the landfilling process of garbage.It is difficult to achieve satisfied results via conventional treatment technology.In this study,a proposal was put forward that utilizing the photo-Fenton reaction to degrade landfill leachate during the membrane separation process,and the target was implemented by cement/FeC₂O₄hollow fiber membrane which prepared through dry-wet spinning technology.The specific research content is as follows:First of all,an asymmetric cement hollow fiber membrane was prepared via the method combining phase inversion with hydration.The effects of hydration time on the water contact angle,pure water flux and surface roughness of the hollow fiber membrane of cement were investigated,and the research manifested that the water contact angle,pure water flux,and surface roughness declined as the hydration time of the hollow fiber membrane prolonged,not merely,complex silicate compounds such as Ca₇Si₆O₁₈CO₃?H₂O?₂also appeared and the porosity decreased.Simultaneously,the finger hole thickness decreased with the increase of the traction rate.Secondly,using PVDF and FeC₂O₄ as raw materials to prepare flat films,and the COD removal effect of light Fenton reaction in landfill leachate and the issue of valence state conversion of Fe²⁺/Fe³⁺on the membrane were explored.The results of X-ray photoelectron spectroscopy?XPS?and COD digestion demonstrated that the Fe³⁺concentration on the surface of the membrane increased from 0%to 60.6%after2 hours of reaction.When the FeC₂O₄addition amount was 3 wt%and the H₂O₂concentration was 2 mol/L,the COD removal rate was about 85%.Finally,the synergistic mechanism of landfill leachate treatment with cement/FeC₂O₄hollow fiber membrane and light Fenton was preliminary studied.The structure and phase changes of cement/FeC₂O₄hollow fiber membranes were analyzed by environmental scanning electron microscopy?SEM?and X-ray diffractometer?XRD?.The effects of pH,H₂O₂concentration and reaction time on the removal rate of COD were also explored.The results indicated that the water contact angle of the hollow fiber membrane dropped continuously with the extension of hydration time on account of the fully hydrated cement particles on the outer surface of the membrane.The results of XRD showed that the cement products such as Ca₅Si₆O₁₆?OH?₂,Ca₅(Si₆O₁₇)?H₂O?₅and hydrated aluminum silicate appear gradually;when the H₂O₂concentration in the leachate was 0.2 mol/L,pH=4 and the illumination time was 120 min,the COD removal rate was 72%.