| Leachate is a type of organic wastewater containing large amounts of pollutant with high concentration. And quantity and quality of leachate vary significantly with landfills and their ages. Therefore, leachate is always difficult to treat. Nowadays, semi-aerobic aged refuse bioreactor under batch injection conditions has been used to treat leachate, but capacity of the treatment is poor. The objective of this study is to investigate a higher capacity by continuous injection of leachate. By simulated experiments, comparison of batch and continuous injection conditions and a two-stage bioreactor were studied.The comparison study shows that when hydraulic load increased from 41.94 L/d to 104.85 L/d per cubic meter aged refuse, the removal efficiencies of COD under batch and continuous injection conditions are respectively decreased from 95.75% and 96.69% to 79.76% and 85.68%, with that of NH3-N respectively decreased from 99.71% and 99.65% to 80.73% and 86.51%. Therefore, in case of 104.85 L/d of hydraulic load per cubic meter aged refuse, the removal efficiencies of COD and NH3-N in leachate under the continuous are more than that under the batch by 5.92% and 5.78%, respectively.Based on experiment of the two-stage bioreactor, the result shows that with improvement of hydraulic load, the removal efficiencies of COD, NH3-N and TN by the first stage bioreactor straightly drop, whereas those by the second stage bioreactor fluctuate. When hydraulic load increased from 41.94 L/d to 125.82 L/d per cubic meter aged refuse, the removal efficiencies of COD, NH3-N and TN by the two-stage bioreactor are respectively decreased from 94%, 99.9% and 73.38% to 88.85%, 96.2% and 72.42%.The study shows that continuous injection of leachate and the two-stage bioreactor result in a more treatment capacity. The paper gives reference for further study of leachate treatment by semi-aerobic aged refuse bioreactors.
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