Landfill Leachate Pretreatment Process Optimization Research

Leachate contains large amounts of organic pollutants, ammonia and heavy metals, if not treated, will affect surrounding groundwater, soil, etc., and cause serious pollution. A lot of landfill leachate treatment processes usually conclude aerobic biological treatment, anaerobic biological treatment and anaerobic - aerobic combination treatment, because of high ammonia content and low biodegradability, landfill leachate is required to make general pretreatment with physical and chemical methods before biological treatment in order to reduce ammonia concentration and improve the biodegradability. Currently, pretreatment of landfill leachate mainly focuses on micro-electrolysis, Fenton oxidation, advanced oxidation, ammonia stripping and coagulation precipitation. But the application of physical and chemical pretreatment of landfill leachate on the same comparative study rarely is reported, this study uses carbon micro electrolysis, coagulation, and ammonia stripping and three kinds of pretreatment pretreatment of landfill leachate investigated in different conditions, finds out the single best way of using the pre-conditions, then the combination of the three pretreatment methods is applied to study the pretreatment effect of landfill leachate, and the research results are based on re-combination to optimize combination process.Microelectrolysis has good effect on the leachate treatment, the tests are investigated by sponge iron and cast iron, iron carbon mixing ratio, pH, aeration rate, the ratio of the influent COD_cr concentration and hydraulic retention time on garbage seepage the impact of the filtrate, the results show that: Electrolysis is the process for optimum conditions are pH 5.0, 1:1 ratio of iron and carbon, solid-liquid ratio of 1:2, the aeration capacity of 50L / h. Under these conditions, the process can not only degrade away more than 50% of landfill leachate COD_cr in the 60 min, decolorization rate is 95% or more;aeration reactor effectively solve the problem of fill compaction.The research compares the four coagulant by sulfate, aluminum sulfate, PAC and ferric chloride in the test. In the pH value of 7 , COD_cr concentration of 7358 mg / L , the test is measured by the four coagulant respectively COD_cr, SS removal efficiency, experiments show that: ferric chloride is the best treatment of landfill leachate of coagulant; and is aimed at dosage, stirring speed, pH, deposition time and other factors to consider landfill leachate COD_cr, SS effects, concluding: The pH value of 7, COD_cr concentration of 7358mg / L, under the conditions when the ferric chloride best dosage is 0.175g / L; the best stirring speed is 200r/min;, COD_cr removal rate is about 50%; optimum sedimentation time is 40min.Leachate ammonia concentration is especially high, for the normal operation of subsequent biochemical segment, increases the ammonia stripping process. Experiments studies pH, temperature, gas-liquid ratio on the stripping efficiency. The results show that: ammonia stripping process is the best pH value of 11 operating conditions, gas-water ratio of 4200:1, blowing off time 1 hour; temperature is room temperature, the ammonia nitrogen removal rate is up to 89.63%.Finally, the tests of these three different pretreatment combinations compare the treatment effect, the process of electrolysis - coagulation - ammonia stripping is the best combination.