| Sanitary landfilling is the most common way to dispose of municipal solid waste in China, playing an important role in the long-time. In this case, one of the most significant impacts of a landfill on the surrounding environmenthas been consistently identified as being caused by leachate. In recent years, the development of anaerobic bioreactor and aged refuse biofilter technology proposed new approachs for leachate treatment, but these technologies has some deficiencies, such as a poor efficiency of nitrogen pollutants removal. Therefore, the united bioreactor landfill, evolved from the semi-aerobic aged refuse biofilter combined with anaerobic bioreactor, is introduced in this paper. Through laboratory simulation study, the optimal operational condition was revealed, and the low of degradation of solid-phase in the conditions was discussed.By the orthogonal experiment of four important factors inculed temperature, leachate distribution frequency, recharge capacity and influent COD concentration, the optimal operation parameters of the semi-aerobic aged refuse biofilter was the condicont with the temperature of 30℃, the leachate distribution frequency of once every 3 days, recharge capacity of 2L every time, influent COD concentration of 50000mg/L, which of the hydraulic loading is 30L/m3 every times, organic load is about 550g/(m3.d). The results show that the remove efficiency of COD and NH3-N can reach over 99% by the using of semi-aerobic aged refuse biofilter, but the remove efficiency of TN is lower(between80.3% and 98.9%).So, the removal of total nitrogen should be considered as the main limiting factor when the design for semi-aerobic aged refuse biofilter.Through the determinatinon for the indicators of solid waste, the results show that:At first, the sedimentation rate of the three anaerobic column were 24.24%,18.90% and 25.35%, the moisture content was about 70%, the content of organic carbon changed little(between 347.86g/kg and 583.64g/kg) compared to the initial value (387.27g/kg), the removal rates of TC were 3.14%,3.66%,4.07%, the result of BDM showed irregular fluctuations.while the trend of nitrate nitrogen is decline(1954mg/kg to 150mg/kg) and total nitrogen showed irregular fluctuations (between 4600mg/kg and 16000mg/kg), ammonium nitrogen concentration was significantly increased(45mg/kg to 2000mg/kg). the results show that the united bioreactor with leachate recirculation can promote the removal of the organic and nitrogen substances, and accelerate the degradation of solid waste. Second, the settlement of aged refuse in the semi-aerobic bioreactor column was little, the moisture content of aged refuse was increased(31.84% to between 38.39% and 58.14%), while the change of ash content and fuel are little and no low. The rising trend of total nitrogen was mainly due to leachate recirculation. Compared to the concentration in the anaerobic column, the the concentration of ammonium nitrogen in the semi-aerobic bioreactor column was low (between 22mg/kg to 135mg/kg). The accumulation of ammonia and nitrate nitrogen was not appeared in the semi-aerobic aged refuse biofilte, which showed that it can remove organic and nitrogen pollutants effectively.This study showed that the united bioreactor landfill can accelerates the degradation of MSW faster, at the same time it can effectively remove organic pollutants, especially for the removal of nitrogen pollutants. It provided theoretical support for the evaluation system of landfill stabilization and the practical application of bioreactor and semi-aerobic aged refuse biofilter. |
PDF Full Text Request