Pretreatment Of Landfill Leachate In Lanzhou By Coagulation And Electrochemical Oxidation Process

Sanitary landfill is the city garbage disposal methods at this stage mainly,the landfill will produce a large amount of leachate,landfill leachate on groundwater and soil,the surrounding environment will cause serious pollution,leachate and organic components of high content,poor biodegradability also contain toxic and harmful substances,and the processing ability the treatment efficiency of serious impediment to conventional treatment methods,the methods to dispose the leachate is the main method and biochemical method,three kinds of combination process.In this paper the leachate treatment difficulties of adopting combined process of coagulation + electrochemical oxidation method for Lanzhou landfill leachate were studied,the maximum degree of permeability decrease the content of ammonia and COD in leachate and improve the biodegradability,create test conditions for the subsequent biochemical treatment better,achieve the pretreatment in the combined process of.Lanzhou is a typical city in the northwest cold and arid region.The landfill leachate in Lanzhou has the characteristics of landfill leachate in the whole country and the particularity of landfill leachate in Northwest China.In this paper,Lanzhou municipal landfill leachate is studied in the following three aspects:(1)Simulated landfill experiment.Through consulting the literature and investigating the garbage components in Lanzhou,the distribution ratio of the garbage group was determined and the landfill experiment was simulated.By controlling the water content in garbage,the contents of ammonia nitrogen and COD in landfill waste disposal stage were measured,and the degradation rule of garbage was analyzed,which provides theoretical data for landfill design and operation.The simulated landfill experiment by comparing the experimental results under the two conditions that keep the garbage optimum moisture content can effectively increase the waste degradation rate,promote the rapid degradation of organic waste,shorten the degradation period,have certain reference value to control the actu al landfill in water.Garbage obvious degradation organic matter in landfill process,ammonia concentration showed a steady upward trend in the landfill,landfill waste degradation in the column until after the full concentration was stable,from the initial 283mg/L,gradually increased to 1000mg/L,the fluctuations in 1000mg/L;difference between COD concentration and ammonia concentration variation of COD concentration is large,fast the rise in the landfill 10 days by the 2822mg/L rapid rise to 51019mg/L,decreased gradually after the final stable in 4400mg/L.(2)Coagulation experiment.The experimental samples for environmental protection,leachate treatment system in adjusting pool water samples is determined by comparing with the experimental data of landfill,coagulation water is COD the highest water content filling period,this experiment is for the actual COD content in landfill peak water processing experiment.Three effective coagulants,PAC,PFS and PFC,were selected in the experiment.The experimental conditions for determining the best removal rate of COD and NH3-N were determined by adjusting coagulant types,coagulant dosage and p H value.When the coagulant is PAC+PFS,the dosage is 8g/L and the p H value is 7.5,the coagulation experiment ca n achieve the best removal effect.The ammonia nitrogen removal rate is 40.2% and the COD removal rate is 48.9% at this time.By adjusting the dosage of PAC and PFS,the removal rate of PAC:PFS is the highest when it is 1:3.(3)Electrochemical experiments.The water quality of the electrochemical experiment is the best effluent quality of coagulation experiment.The experimental conditions were determined by adjusting the value of electrode plate,current density,NaCl dosage and pH value,so as to achieve the best place effect,and lay the foundation for subsequent biochemical experiments.Orthogonal experiment was used to confirm that the electrode was Ti/RuO2-IrO2-TiO2,the dosage of NaCl was 2g/L,the current density was 7.5A/dm2,and the p H value was 7,and the removal rate of experimental effluent was the highest,ammonia nitrogen removal rate was 56.5%,and CODcr removal rate was 59.3%.The water quality of the experiment: the concentration of ammonia nitrogen is 2153mg/L,the concentration of COD is 68312 mg/L,the concentration of BOD5 is 11164mg/L,and the B:C is 0.18.The effluent quality after coagulation + electrochemical experiment: the concentration of ammonia nitrogen is 477mg/L,the concentration of COD is 15441mg/L,the concentration of BOD5 is 6537mg/L,and the B:C is 0.42.The removal rate of ammonia nitrogen was 77.8%,the removal rate of COD was 77.4%,the B:C increased from 0.18 to 0.42,and the biodegradability increased greatly.