Field assessment of stratified aged-refuse-based reactor for landfill leachate treatment

The aim of this study was to investigate the engineering applicability of the stratified aged-refuse-based process for landfill leachate treatment. In this work, a pilot-scale (10 m(3) day(-1)) and a demonstration-scale (200 m(3) day(-1)) stratified reactor, containing the aged refuse excavated from an 8-year-old closed landfill cell, were used as a medium by which to treat landfill leachate generated in the Shanghai Refuse Landfill (SRL). The preliminary-treated leachate with initial CODcr, NH3-N and total-N concentrations of 2387-8592, 1431-2145 and 1290-2188 mg L-1, respectively, was intermittently sprayed over the refuse surface eight times a day with 3 h per interval in the pilot study. The results from the pilot operation showed that on average 89.5% of COD, 98.8% of NH3-N and 52.6% of total N could be removed from a hydraulic load of 0.267-0.444 m(3) m(-3) refuse day(-1). Additionally, similar results were observed for the demonstration system even with the leachate of low BOD5/COD ratios (0.17-0.19). The investment and operational costs of this stratified process were about 20 000 yuan (E2200) and 1-2 yuan (E0.11-0.22) per m(3) leachate treated, respectively. Taken together, the stratified process has some significant advantages including low operation cost, easy maintenance and good adaptability to the leachate of variable quality, which makes this process a viable alternative for the treatment of landfill leachate.