| Landfill is one of the most widely technology used to dispose solid refuse compared with composting and waste incineration. However, leachate generated during the landfill process will contaminate the environment seriously, in addition, higher ammonia nitrogen and lower organic concentration as the result of longer landfilling time makes leachate more difficult to deal with. The "Municipal Solid Waste Landfill pollution Control Standard"(GB16889-2008) promulgated recently stricter limits for leachate discharge and put forward a challenge for traditional landfill leachate treatment technology. Therefore, the research on landfill leachate treatment has an important practical application value.It is difficult to use just one simple technology to completely solve the problem of landfill leachate due to its complexity. With promulgation and implementation of the new standard, it is necessary to update the existing leachate treatment facilities and optimize the combination of new facilities. In recent years, seeking an efficient, economic, energy saving using physicochemical and biochemical method becomes a hotspot and difficulty of leachate treatment.In this study, the effect of dissolved oxygen (DO) on the shortcut nitrification of aged landfill leachate and microbial community structure using sequencing batch reactor (SBR) were investigated. An aged refuse bioreactor constructed with aged refuse of more than ten years old sampled from Shanghai Laogang municipal solid waste landfill was to investigate the removal efficiency of pollutant during anaerobic process, the effluent of which was then treated by the advanced oxidation technology as an advanced treatment. It was expected to provide references to the treatment of landfill leachate.Conclusions were drawn as follows:(1) The maximum rate of nitrification was found in the group with low DO concentration(0.2～0.5mg/L), after17h of reaction, the value of nitrate nitrogen/ammonia nitrogen was1.05and ammonia nitrogen load reached to1.5 kg/(kgMLSS-d), the effluent could meet the requirement of subsequent Anammox treatment. DGGE fingerprint of the microbial community revealed that the dominant bacteria were Uncultured Bacteroidetes bacteriu, uncultured Thermus/Deinococcus group bacterium, uncultured Candidatus Amoebophilus sp. Ect.DO had limited impact on bacterial community structure.(2) The performance of Anammox reactor treating leachate showed that the removal rate of total nitrogen was80%when the nitrogen load between0.74g/kg(vs)-d and1.35g/kg(vs)·d, and the removal rate of total nitrogen decreased as the total nitrogen load increased; The study of different feeding patens showed that feeding style played an important role in reactor operation and the maximum total nitrogen removal rate of52.2%was achieved with submerged reactor, and other removal were35.7%,21.1%respectively with half submerged and opened reactor, therefor, submerged reactor has a better removal of nitrogen.(3) The results of photocatalytic oxidation degradation experiment showed that when COD concentration was500-600mg/L, COD had the highest removal (42.7%) under the TiO2concentration was1mg/L, and TiO2had a slightly better removal performance compared to BiOBr when the both concentration of TiO2and BiOBr were0.5mg/L.This research suggested that ammonia nitrogen and organic in leachate was effectively treated by the integration processes:SBR and Anammox and photocatalytic oxidation. |
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