Research On Landfill Leachate Recirculation Treatment In Pilot-scale Experiment

Leachate recirculation treatment has been researched by many researchers, but it is mainly restrained in lab-scale experiment and full-scale application is seldom reported. As for the limitation of experimental environment and scale in lab, there are some differences between the results of lab-scale experiment and of pilot-scale experiment. The purpose of this research is to find the effect of Leachate recirculation treatment in pilot-scale experiment, which provide more accurate technique parameters for full-scale application, and also provide proof for theoretical research and parameters for project design.The pilot-scale experiment was operated at Fuzhou Hong Miaoling Landfill. A cell was dug downward whose surface dimension was 18×13m and bottom dimension was 10×5.4m.It prevented liquid from transition between cell and surrounding by geocloth-geomembrane-geocloth. By changing influent concentration hydraulic load organic load and irrigating frequency, the influence of irrigation on COD BOD5 and NH3-N removal ratio was researched under the sunny conditions and cloudy conditions respectively. Meanwhile the effect on environment was evaluated accordingly. Through comparison of results of lab-scale and pilot-scale experiment, difference was found.The research showed that it was effective for Municipal Solid Waste (MSW) to deal fresh Leachate. After 12-day-low-volume irrigation, the activity of microbe was improved so obviously that COD removal ratio reached 95% when the influent COD concentration was 16000~24000mg/l. After the waste bed was stable, COD removal ratio could reach 80% when hydraulic load varied from 3.4 to 9.16 ml/l.d, organic load 43.8 to 167.2 mg/l.d, velocity 581/min and frequency 3 times, but it was more appropriate at 4~5 ml/l.d of hydraulic load Everytime. As for the influence of the factor such as rainfall and fog, the irrigating hydraulic load should be no more than 3.41ml/l.d everytime. Under that condition, COD removal ratio could reach more than 80%. The same high removal ratiocould also be reached from BOD5 and NH3-N, which the BOD5 removal ratio was higher than that of COD under the same conditions and could maintain at more than 95%. The removal ratio of NH3-N maintained at 50~70%. By the research of terrestrial heat during irrigation, the results showed that the temperature at the outlet reached 31℃ whereas it at the height of 1 m over the waste bed was only 19 ℃. So the results could be referred that the temperature in waste bed was over 31 ℃. Through checking the concentration of H2S by instrument, it accorded with the correlative policy and regulations.