Study On Process About A Modified Slow Sand Filtration Treating Landfill Leachate

Nowadays, due to multiple advantages, sanitary landfill has become the main process,which used to treat the domestic municipal solid waste. But landfill leachate produced by sanitary process has high content of pollutant, heavy flow and bad biochemical. It is complex and costly to treat landfill leachate. We try to make full use of merits of slow filter to lower the cost which is used in the pre-processing stage, to create favorable conditions for further processing.The landfill leachate in our study came from Jinan landfill urban sanitation. After simply adjustment, the landfill leachate is sent to modified slow filter. Main parameters which are studied in this experiment are as followings: aeration mode, surface activated carbon thickness, water layer height, depth of filter.They are considered to how they impact the speed, removal and removal quantity. Conclusions that the study gets are as followings:Firstly, the best experimental condition is determined by cross-over trials. Intermittent aeration is used; 1cm thickness of activated carbon is laid to the filter surface; the height of water layer is controlled at 60cm. At this point, the effect of the slow filter is modified best, and the removal of pollutant is the highest.Secondly, speed of the filter can both be reduced by intermittent aeration and constant. But in constant aeration, total quantity is reduced notably, because of lowest speed. However, in intermittent aeration, speed of the filter can be lowered slightly; total removal quantity can be reduced most.Thirdly, the amount of pollution removed can reach the maximum when the layer thickness of the carbon is laid of 1cm. If the thickness is increased constantly, the amount of pollutant removed declines fast. If the thickness is lowered, the removal rate of pollutant is far away from our aim.Fourthly, water height is maintained at 60cm, total removal quantity is the highest. When water layer height is set at 30cm, total removal quantity is lower than that of 60cm, because of low speed.While water height is maintained at 80cm, speed is increased more, but removal of the pollutant is reduced obviously.Fifthly, when water height is set at 60cm, intermittent aeration is used, the layer thickness of the carbon is laid of 1cm, in different depth of the filter; the removal rate of the pollutant can be increased at first, then be reduced.When the depth of the filter is located at 25cm, the total removal quantity can get the maximum. Rate of the added is reduced, if depth of the filter constantly added.