Research On UV-Fenton Treatment Of Concentrated Water From Nanofiltration Of Landfill Leachate

Membrane combined with biotreatment has widely applied in leachate treatment inorder to satisfy new discharge demand proposed by Standard for Pollution Control onthe Landfill Site of Municipal Solid Waste GB16889-2008. Therefore with thecharacteristics of high organic concentration, high salinity, low biodegradability,membrane concentrated water produced during this process would contaminate theenvironment if not treated properly. The study focused on treatment of membraneconcentrated water by Advanced Oxidation Processes.UV-Fenton and Fenton had good results on the treatment of concentrated waterafter nanofiltration from Asuwei Sanitary Landfill Site. H₂O₂dosage, FeSO₄·7H₂Odosage, pH and reaction time had significant effects on Fenton process performance.Take TOC removal as an example, removal rate increased as H₂O₂dosage increasinguntil dosage concentration was13320mg/L; removal increased as FeSO₄·7H₂O dosageincreasing until dosage concentration was5500mg/L; optimal pH value was4, andreaction almost completed in2h. H₂O₂dosage, FeSO₄·7H₂O dosage, pH and reactiontimealso had significant effects on UV-Fenton process performance. Take TOC removalas an example, removal rate increased as H₂O₂dosage increasing until dosageconcentration was9990mg/L; removal had a sharp increase followed by moderateincrease as FeSO₄·7H₂O dosage reached2200mg/L; optimal pH value was3, andreaction almost completed in2h. UV-Fenton process had higher removal rate thanFenton process under same condition. Choice of UV-Fenton could reduce chemicaldosage and reduce reaction time as well.Effects on treatment of concentrated water after nanofiltration from BeishenshuSanitary Landfill Site by UV-Fenton were studied by using Response Surface Method.Linear Model of COD_Crand TOC removal rate of H₂O₂dosage, FeSO₄·7H₂O dosage,pH and reaction time had passed test of significance. H₂O₂dosage and pH had stronglinear relationship with removal rate. Removal rate increased with H₂O₂dosageincreasing and decreased with pH increasing within certain range. Optimal parameterwas as follows: H₂O₂dosage was between40mL/L⁴5mL/L, pH was between3.0³.5，FeSO₄·7H₂O dosage was3300mg/L，and reaction time was120min. Pilot-scale investigation was launched under specific condition mentioned aboveon treatment of concentrated water after nanofiltration from Beishenshu SanitaryLandfill Site by UV-Fenton process. Results showed that system had good opearations.COD_Cr removal rate was between74%and83%, and TOC removal rate was between67%and88%, organic pollutants had effectively removed. Three-dimensionalfluorescence method showed that UV-Fenton removed humic acid and fulvic acidexisting in concentrated water.