Studies On Semi-aerobic Landfill Leachate Denitrification At Two Different Airway-caliber

Nowadays,with the increasing of the population and urbanization level in our country,large crowds of people move into cities.The economic prosperity leads to the increment of life garbage,bringing huge pressure to the cities.Semi-aerobic landfill technology has a strong advantage in speeding up the stability of garbage and effectively removing the nitrogenous and carboniferous substances.Different pipe diameter of airway tubes has a great effect on the degradation of garbage,but few people have carried out the further study.This experiment is a simulating experiment on semi-aerobic landfill of the life garbage in the laboratory.There are two sets of landfill device,which are disposed into the two biochemistry incubators,ranging from 20℃ to 35℃ and 20℃ to 55℃.In each set,the three landfill devices includes two semi-aerobic landfill devices with different pipe diameter(1#、4#:Φ8mm,2#、5#:Φ4mm)of airway tubes and one anaerobic landfill device as a reference.The thesis mainly conducts the data analysis on the organic compounds degradation of landfill in different pipe diameter,the features of nitrogen removal of leachate and the nitrogen transformation in each layer of leachate.The main conclusions in this thesis are as follows:(1)organic compounds degradation: The declining speed of COD concentration are all 1#>2#>3# and 4#>5#>6#,and the removal rate of COD in 1# and 4#reaches 82.5% and 88.2% respectively,both higher than 2# and 5# under the same conditions.However,the removal rate of COD in referential 3# and 6# anaerobic landfill devices only reaches 34.3% and 47.1%.Thus compared with anaerobic landfill devices,the semi-aerobic landfill devices are conducive to the degradation of organic compounds.Also the bigger the pipe diameter of the airway tube in the semi-aerobic landfill devices is,the faster the degradation efficiency is.(2)nitrogen removal of leachate: the proportion of ammonia-nitrogen is higher than that of total nitrogen in the leachate of life garbage,and the changing trend is the same as total nitrogen,proving that ammonia-nitrogen is the major component of the nitrogen pollutants in the garbage.In comparison with anaerobic landfill devices,the semi-aerobic landfill devices let more air into the devices equipped with the airway tube connecting with the outside.The semi-aerobic landfill devices can finish removing ammonia-nitrogen preliminarily in a short time so that the pollution of organic nitrogen compounds can be decreased faster.(3)the nitrogen transformation in each layer of leachate: in this experiment,the upper layer is under aerobic condition chronically in the semi-aerobic landfill devices,which can proceed nitrification of ammonia-nitrogen steadily.By the end of the experiment,the nitrate concentration is above 140mg/L at the upper leachate in the four semi-aerobic landfill devices,exceeding the upper layer of ammonia-nitrogen in the corresponding devices at the same time.The experimental results show that most of the ammonia-nitrogen has transformed into nitrate nitrogen.Nevertheless,due to the lower layer and bottom are under anaerobic or anoxic condition,nitrification can not carry on smoothly.The upper layer of nitrate nitrogen is leached to bottom through water distribution.(4)Through the derived models,this thesis conducts the data fitting on the change of total nitrogen in the bottom and concentration of ammonia-nitrogen and reflects the changing trend of concentration of total nitrogen and ammonia-nitrogen in this semi-aerobic landfill experiment.Meanwhile,the thesis forecasts the time when the leachate can meet the national discharged standard of life garbage and sewage and again proves that with the increase of the pipe diameter of leachate airway tube,the water-denitrification of leachate will be reinforced.