Aged Leachate Treatment by Sequencing Aged Refuse Bioreactors

In this study, the aged refuse excavated from a 10-year old closed landfill compartment at Shanghai Laogang Refuse Landfill was used as the substrate in a sequencing aged refuse bioreactor process for treatment of aged landfill leachate which sampled from the same landfill. Typically, screened aged refuse with a diameter less than 8 mm was used as biofiltration material in the two round shaped bioreactor with an inner diameter of 40 cm and a height of 130 cm. Influent aged leachate with initial CODCr, TN and NH3-N concentrations of 2050-2530, 1920-2710 and 1800-2500 mg/L, respectively, was introduced into the system. The corresponding concentrations in the effluent were reduced to below 400-600, 400-750, and below 15 mg/L, respectively. The sequencing aged refuse process is not effective in TN and COD removal for aged leachate treatment. It may mainly due to its low biodegradable and shortage of valid carbon source. The treatment mechanism of nitrogen removal was studied. In the process, the nitrogen removal is mainly due to the nitrate denitrification in the anoxic bioreactor, simultaneous nitrification and denitrification is exist in the aerobic bioreactor, but is not the main nitrogen removal way, which is different from the nitrogen removal mechanism of fresh leachate treatment.