Pretreatment Of Landfill Leachate In Lanzhou By Coagulation And Electro Fenton Oxidation Process

With the rapid development of cities and the improvement of people's living standards,more and more garbage is produced in life and production.Sanitary landfill is the most widely used disposal method for garbage disposal in china.Landfill leachate produced by landfill method has caused serious harm to water quality and living environment in various regions,the leachate has high content of organic pollutants,great variation of water quality and quantity,the capacity and efficiency of conventional treatment methods are seriously affected.At a present,the treatment methods of leachate include physical-chemical method,biological method,land treatment method,etc.In this paper,bentonite combined with electro-fenton oxidation process was used to treat landfill leachate,so as to reduce the content of ammonia nitrogen and COD in the leachate and improve the biodegradability of leachate,providing a basis for the subsequent biochemical treatment and achieving the role of pretreatment in the combined method.In this paper,experimental study on landfill leachate is carried out from three aspects.?1?bentonite experiment.In this experiment,the leachate from the regulating tank of a waste disposal site in Lanzhou City was selected as the experimental water sample,and the experimental study on the treatment of the water quality in the actual landfill site was carried out.Ammonia nitrogen concentration was 334 mg/L,COD concentration was 8525mg/L.Pretreatment of landfill leachate with sodium bentonite and organic bentonite,Through single factor experiment and orthogonal experiment,we can know that:bentonite dosage,water conservancy condition,pH and static time are the main factors affecting bentonite experiment.The optimum experimental conditions for treating landfill leachate with sodium bentonite are as follows:dosage is 3g/L,hydraulic condition is 270r/min?3min?,pH is value7.0 and standing for is 1h.Under these experimental conditions,the removal rate of COD and ammonia nitrogen in leachate was 42.52%and 36.53%,At the same time,the optimum experimental conditions for treating landfill leachate with organobentonite are as follows:dosage is 3g/L,hydraulic condition is 270r/min?3min?,pH is value 7.0 and standing for is 1h.Under these experimental conditions,the removal rate of COD and ammonia nitrogen in leachate was 49.56%and 48.20%.?2?electric fenton experiment.Ammonia nitrogen concentration was 334 mg/L,COD concentration was 8525 mg/L.The optimum experimental conditions were determined by adjusting the Fe²⁺concentration,pH,temperature and voltage,so as to achieve the best treatment efficiency.Through single factor experiment and orthogonal experiment,we can know that:Fe²⁺concentration is 20mmol/L,pH value is 3.0,temperature is 30?and voltage is 7V.under the experimental conditions,The COD removal rate was 55.43%.?3?combined experiment.Ammonia nitrogen concentration was 334 mg/L,COD concentration was 8525 mg/L.The effluent quality of the combined experimental water sample is sodium bentonite and organic bentonite,under these conditions,electrochemical experiments were carried out,the optimum experimental conditions were determined by adjusting the Fe²⁺concentration,pH,temperature and voltage,after the sodium bentonite experiment effluent,the electrochemical experiments showed that:Fe²⁺concentration is3mol/L,pH value is 3.0,temperature is 30?and voltage is 7V.under the experimental conditions,the COD removal rate was 77.71%.After the organic bentonite experiment effluent,the electrochemical experiments showed that:Fe²⁺concentration is 3mol/L,pH value is 3.0,temperature is 30?and voltage is 7V.under the experimental conditions,the COD removal rate was 81.23%.Water quality of experimental influent:Ammonia nitrogen concentration was 334 mg/L,COD concentration was 8525 mg/L,BOD₅ concentration was 1619 mg/L and B:C was 0.19.The effluent quality of sodium bentonite combined with electric fenton experiment is as follows:COD concentration was 1900 mg/L,BOD₅ concentration was 1036 mg/L and B:C was 0.36.The removal rate of COD by sodium bentonite combined with electroFenton experiment was 77.71%,the B:C increased from 0.19 to 0.36,meanwhile,the removal rate of COD by organobentonite combined with electroFenton experiment is 81.23%.The COD concentration of effluent water is 1600 mg/L and BOD₅ concentration is 939 mg/L,the B:C increased from 0.19 to 0.42,the biodegradability has been significantly improved,which promotes the subsequent biochemical treatment.It is of great significance to the subsequent biochemical treatment and achieves the original experimental purpose.