Coagulation-PBER/PDS Catalytic Oxidation Treatment Of Leachate From Garbage Transfer Station

Landfill leachate from transfer station has the characteristics of high organic concentration,high ammonia nitrogen,high salinity,high oil and grease,and the water source is scattered,the overall water volume is relatively small and the water quality fluctuates,which is a large load for the traditional biological treatment,resulting in the treated effluent is difficult to meet the discharge requirements of the《Water Quality Standard for Sewage Discharged into Urban Sewers》（GB/T31962-2015）,while the electro-catalytic oxidation technology has the advantages of simple structure,small footprint and easy management,which is ideal for the engineering and construction needs of decentralized wastewater treatment such as transfer stations.The three-dimensional electrochemical oxidation technology efficiently generates a large number of hydroxyl radicals（·OH）to effectively degrade and remove pollutants,although it has the characteristics of high mass transfer efficiency and high current efficiency,it has the problems of low pollutant degradation rate,limited removal effect and high energy consumption for the treatment of high concentration organic wastewater.The persulfate oxidation technology（SR-AOPs）is mainly used to oxidize and degrade organic pollutants by activating persulfate to produce strong oxidizing sulfate radical（SO₄^-·）,with advantages of high efficiency,environmental protection and stability,it has attracted more and more attention in the field of high concentration organic wastewater treatment.However,there is a problem of low activation efficiency of single activation method.In this thesis,based on the synergistic mechanism of filled-bed electrochemical reactor（PBER）and persulfate（PDS）activation,the coupled system of PBER and PDS activation is constructed to achieve low energy consumption and high efficiency degradation of landfill leachate from transfer station and achieve the standard treatment of nadir.In this paper,coagulation precipitation is used as a pretreatment process to provide a good influent water quality environment for PBER,it effectively removes suspended matter and oil concentration,and avoids the problem of uneven electric field distribution caused by the clogging of the PBER bed,which leads to the decrease of treatment efficiency.In addition,most studies on SR-AOPs focus on the treatment of laboratory simulated wastewater,while few studies and applications of actual wastewater with complex components,such as landfill leachate from transfer station,therefore,the research on SR-AOPs for the treatment of landfill leachate from transfer station has more significance and engineering application value,it is helpful to develop an efficient treatment process of leachate which is easy to be applied in practical engineering.The main conclusions are as follows:1.In the experiment of coagulation process pretreatment of leachate in transfer station,orthogonal test and single factor optimization experiment were used,the effects of dosage of demulsifier Na OH,coagulant PAC and coagulant aid PAM on COD,ammonia nitrogen and SS of leachate were studied,the optimum process parameters were determined.The results show that,the optimal dosages of PAC and PAM were1000 mg/L and 10 mg/L,respectively,when Na OH was demulsified and leachate was adjusted to p H=8,the stirring mode was fast for 2 min at 300 r/min,slow for 5 min at60 r/min,and the sedimentation time was 30 min,and the removal rates of COD,NH₄⁺-N and SS were 45.7%,27.7%and 94.8%.2.The PBER system was tested for electrocatalytic oxidation of coagulated leachate to investigate the optimal working parameters,and the experimental results showed that,the Pb O₂/Ti electrode plate was the anode,and the best treatment effect was achieved at a current density of 100 A/m² without additional electrolyte injection,the removal rates of COD,NH₄⁺-N and chroma were 58.5%,62.8%and 85.0%,respectively.In PBER/PDS coupling system and the best effect was enhanced at the initial p H=7 and the PDS dosage of 40 mmol/L.The final removal rates of COD,NH₄⁺-N and chromaticity were 80.5%,69.5%and 95.5%,respectively.3.The effects of different factors on COD degradation in PBER and PBER/PDS systems were investigated and the kinetic characteristics and laws of COD degradation were analyzed.The kinetic fitting of COD degradation in different experimental conditions showed that the results were in accordance with the quasi-level kinetic model with good correlation,and the effects of anion concentration in water on the activation effect of PBER/PDS system and the mechanism of action were investigated.4.Comparing the treatment effect and power consumption of different reaction systems,the improvement of COD and chromaticity removal in the PBER/PDS system was more significant,22.0%and 10.5%,respectively,compared to the ammonia nitrogen removal effect,which was only 6.7%,and the energy consumption was significantly reduced.