Test Research On Nitrogen Removal Of Landfill Leachate By Aged Refuse

The ammonia nitrogen(NH3-N) concentration in landfill leacate is usually high,which is in the proportion of 85% in total nitrogen(TN), the effiective removal of NH3-N is an important component of leachate treatment study. The research takes aged-refuse bioreactor into the nitrogen removal of leachate,the mechanisms and differences of nitrogen removal with aged-refuse under the semi-aerobic condition and anereobic condition were studied;through the test,influences of different influent ways and operating ways of leachate reflux and cluster reactors to the removal rate of nitrogen were analysised.finally,a primary technical path of leachate treatment with semi-aerobic aged refuse bioreactor was brought forward.The test results show that at different hydraulic loads,removal rates of NH3-N and TN of leachate with semi-aerobic aged refuse bioreactor were 89.3%-99.9% and 88.3%-92.9%,respectively,higher than those in anereobic condition, accumulation of nitrite nitrogen(NO₂^- -N) and obvious difference in nitrate nitrogen( NO₃^- - N) removal rate in two reactors weren't found.There is remarkable advantage in nitrogen removal of leachate with semi-aerobic aged refuse bioreactor because of active nitrification/denitrification process in semi-aerobic condition.The efficiency of NH3-N and TN removal of effluent from semi-aerobic aged refuse bioreactor decreased when the influent concentrations increased, the NH₃-N removal rate was 99.8% at a influent concentration of 342mg/L.The influent frequency should been controlled in a reasonable range,higher or lower influent frequency is disadvantageous to the process of nitrogen removal.In this test,the best influent frequency was 2d^-1. At a hydraulic load of 0.026L/kg aged refuse each time, the NH3-N and TN removal rate was 99.8% and 86.9% respectively,but treatment efficiency decreased rapidly while higher hydraulic loads were applied.The NO₃^- - N concentration in the test was keeping a lower level,the denitrification process had little relation to influent ways.The measures of leachate reflux and cluster reactors could strengthen nitrification/denitrification processes in the semi-aerobic aged refuse bioreactor and improve efficiency of nitrogen removal.The study result shows that the process of taking semi-aerobic aged refuse bioreactor as main body and physical-chemical process followed as a deep treatment is fleasible in technology,which give a new idea to the treatment of leachate in-site and cycle utlization of aged refuse in closed landfills.