Treatment Of Landfill Leachate Nanofiltration Concentrate By Persulfate Advanced Oxidation Technology

Membrane technology combined with biotreatment has been widely used in leachate treatment.Membrane concentrate with the characteristics of low biodegradability,high organic mater concentration,high color and high salinity produced during this process.The treatment of membrane filter concentrate has received extensive attention.Based on the better treatment performance of sulfate free radical advanced oxidation processes in the organic wastewater,this study focused on the different ways to activate persulfate(?/PS,Anode-Cath/PS/Fe³⁺,?+Anode-Cath/PS/Fe³⁺)to treat landfill nanofiltration concentrate and studied the the feasibility,influencing factors,kinetic analysis and spectral analysis of different systems.In?/PS system,the COD removal followed pseudo-first order kinetics equation.The COD removal rate,removal rate constants and the removal of NH₄⁺-N and color increased first and then tended to be stable with the increasing of PS concentration,which increased with the rising of temperature and decreased with the increasing of initial pH of concentrate.When the PS concentration was 75 mM,the temperature was 80?and the initial pH was 3.0,the final removal rates of COD,NH₄⁺-N and color were 66.3%,89.7%and 98.7%respectively,the removal rate constant was 0.0046 min^-1 in 0-120min and the BOD₅ increased 140mg/L.Compared with simple undivided,anode alone and cathode alone electrochemical system,Anode-Cath/PS/Fe³⁺showed better treatment for concentrate in used of the anode and cathode alternately.The removal of COD,Cl^-,NO₃^--N and color increased first and then decreased with the increasing of current and PS concentration,which increased with the increasing of Fe³⁺concentration and decreased with the increasing of initial pH.When the current was 80mA,Fe³⁺concentration was 15 mM,PS concentration was 37.5Mm and initial Ph was 3.0,the removal of COD,Cl^-,NO₃^--N and color were 54.7%,11.9%,40.1%,79.5%respectively,the BOD₅ increased 40mg/L.The removal curve of COD of Anode-Cath/PS/Fe³⁺was in accordance with the"two-stage"reaction kinetics equation.With current change,the initial removal rate and the maximum removal rate were determined by the effect of chlorine and Fe²⁺activated persulfate,respectively.With Fe³⁺concentration change,the initial removal rate of COD was determined by coagulation,while the maximum removal rate of COD was determined by coagulation and Fe²⁺activated persulfate.When PS concentration change,the initial removal rate and the maximum removal rate were determined by PS concentration and Fe²⁺activated persulfate,respectively.With initial pH change,the initial removal rate of COD was determined by chlorine,while the maximum removal rate of COD was determined by chlorine Fe²⁺activated persulfate.The treatment effect of the system of?+Anode-Cath/PS/Fe³⁺was equal to the sum of effects of?/PS and Anode-Cath/PS/Fe³⁺system,but the efficiency of PS was higher.The increasing of PS concentration,temperature,current and Fe³⁺concentration could promote the removal of COD,color,NO₃^--N and NH₄⁺-N.The increasing initial pH had an inhibitory effect on the removal of these indexes.The increasing of Fe³⁺concentration promoted the removal of Cl^-,the removal of Cl^-was not obvious under other conditions.When the current was 80mA,he temperature was 80?Fe³⁺concentration was 15 mM,PS concentration was 75mM and initial pH was 3.0,the removal of COD,Cl^-,NH₄⁺-N,NO₃^--N and color were 86.6%,4.4%,91.2%,65.1%,97.4 respectively,and the BOD₅increased 180mg/L.?/PS system had good effect on the removal of organic compounds with?-?transition and conjugated system and fluorescence properties,but the removal effect of inorganic anion was not good.Anode-Cath/PS/Fe³⁺system had better removal of the organic compounds with conjugated system and the fluorescence properties of the fulvic acid,but the removal rate of the inorganic anions,?-?transitions and protein-like fluorescence properties were low.?+Anode-Cath/PS/Fe³⁺combined system had better removal effect on the inorganic anion and the organic matter with the characteristics above-mentioned.