Research On Treatment Of Organic Compounds In Reverse Osmosis Concentrate By Oxidation And Adsorption

In recent years,with the wide application of ultrafiltration reverse osmosis（UF RO）dual membrane process,efficient and economical removal of organics in RO concentrated water（ROC）is a bottleneck problem.The purpose of this paper is to select an appropriate treatment process to reduce the organic matter content of RO concentrated water and realize reflux or discharge standard（1）The effect of Fenton Oxidation on the removal of ROC organic matter was studied.Under the single factor experiment and orthogonal experiment,the effect of various factors on Fenton oxidation was analyzed.The fitting equation of organic matter removal rate was obtained by response surface analysis（RSM）.The results showed that the mole ratio of H₂O₂ to Fe²⁺was the most important factor,followed by the dosage of H₂O₂.Under the optimized conditions,the removal rate of non purging organic carbon（NPOC）reached 45.1%.（2）To study the removal effect of powdered activated carbon（PAC）adsorption on organic matter of ROC,adsorption kinetics and isotherm experiments were carried out to explore the adsorption law of PAC.The results showed that the adsorption of ROC organics by PAC conformed to pseudo second-order kinetic model and Freundlich adsorption isotherm model.When PAC dosage was 1.7 g/L and adsorption time was 20 min,the removal rate of npoc from ro concentrated water by single-stage adsorption reached 70%.（3）The effect of pre Fenton oxidation PAC adsorption synergistic experiment and PAC two-stage countercurrent adsorption process on the removal of organic matter from ROC was studied.The results show that Fenton preoxidation may change the species and relative molecular weight of some organic compounds,and decrease the adsorption effect of PAC.The removal rate of NPOC by the combined process is only 35%;Under the condition that the removal rate of NPOC is 72%,the dosage of PAC two-stage countercurrent process is 0.824 g/L,which saves about 53.4%of PAC compared with single-stage adsorption.The relative molecular weight analysis showed that the relative molecular weight of most organic compounds in ROC was less than 1 k Da.The qualitative analysis of three-dimensional fluorescence spectrum showed that the organic compounds in ROC might be humic acid,fulvic acid,hydrophobic acid and other substances.In conclusion,Fenton process has low removal efficiency,high dosage of PAC single-stage adsorption,and poor effect of pre Fenton oxidation PAC adsorption synergistic experiment.Combined with the analysis of process reagent cost,PAC two-stage countercurrent adsorption process is the best choice.