Pretreatment of landfill leachate using deep shaft aeration bioreactor (DSAB) in cold winter season

摘要

A pilot-scale deep shaft aeration bioreactor (DSAB) with 110 m in depth and 0.5 m in diameter for the pretreatment of landfill leachate in winter was operated at a daily treatment scale of around 10-20 tons. It was found that the performance of the DSAB mainly depended on the inflow loads and concentrations of pollutants. NH_3-N, TN, COD, TOC removals of 66-94%, 41 -64%, 67-87%, 55-92% at organic load rate of 1.7-9.4 g CODL~(-1) day~(-1) and hydraulic retention time of 1-2 d were obtained using DSAB, respectively, with the lowest ambient temperature of-3℃. The effluent COD can be reduced to below 1000 mg/L, an acceptable level for advanced treatment using reverse osmosis system, when the influent COD was below 7000 mg/L at 10t/d. The EEM and GPC analysis implied that the non-biodegradable contaminants such as humic- and fulvic-like DOM dominated in the organic fractions of the effluent, which rendered the biological treatment ineffective. Compared with 20-40% removals obtained using traditional biological processes below 15 ℃, DSAB showed a higher treatment efficiency for COD and NH_3-N, even though at adverse conditions of poor carbon source, lower C/N ratio and high nitrite concentrations in the leachate of test.