Research Of Technology And Application Of Aerobic Degradation On The Accelerating Stabilization Process Of Closed Non-Regular Landfills

The advanced technology of aerobic bioreactor can speed up the stabilization process of an old landfill. With the air injection, the Biodegradable organic material (BDM) of MSW will be degradable in an old landfill.The decomposition and biological stabilization of an aerobic landfill is 5-20 times faster than a traditional "dry tombs". The decomposition of the biodegradable matter is very fast in an aerobic landfill. The settlement time of the landfill will be shortened obviously. The leachate disposal costs will be reduced. Compared with the other landfill remediating methods, the aerobic technology has the lower cost and without the secondary pollution.Heishitou Landfill is a closed non-regular landfill. Before the aerobic bioreactor remediation, it polluted the environment and was unstabilized. After 24 months aerobic bioreactor operation, many parameters of Heishitou Landfill has changed obviously. The pH value of solid waste showed a gradual downward trend, from 8.22 at beginning to 7 at the end of the aerobic bioreactor operation. The average moisture content changed in a little scale. With the proper addition of water, the moisture of the landfill was 38% to 39%. The content of BDM in the solid waste decreased from 12.21% at the beginning to 3.1% at the end. The LFG got stabilized after 3 months air injection. The methane content finally reached to less than 1%. The COD and BOD5 of leachate decreased obviously. The total settlement of the landfill at the period of 24 months was 60cm in average.Certain correlation exists between the main technical parameters of the landfill. Higher content of organic matter in the solid waste related to higher content of BDM, higher COD concentration and BOD5 concentration in the leachate, faster landfill subsidence rate, lower bulk density of solid waste.The important conditions of aerobic degradation of solid waste are the content of BDM, oxygen concentration, gas ventilation,the temperature and the humidity on aerobic bioreactor landfill.The mechanism of the aerobic bioreactor shows the key process of the degradation of solid waste in a landfill is chemical reaction. The gas transformation depends on the distribution of air injection well and LFG extraction well, the pressure situation in the landfill, the ventilation of air and the basement and the cover of the landfill. Interval grid-like layout of wells to ensure the uniformity of ventilation is the base to have a good aerobic environment. Liquid migration in the aerobic bioreactor were simulated.To evaluate the landfill stabilization, BDM is the key indicator, the land subsidence rate is the secondary indicator. Methane content, vegetation growth, the concentration of pollutants in leachate can be used as supplementary indicators to evaluate the result of landfill stabilization.