Optimization of Conditions of Digested Sludge Using Landfill Biocover Material for Enhance Methane Oxidation

摘要

The modified digested sludge (MDS) can be used as landfill biocover that serve to minimize CH4 emissions by optimizing CH_4 oxidation. MDS composited by coal ash and digested sludge was studied in this paper. The permeability coefficient and the compressive strength of MDS were tested in full factorial L_9(3~4) experiment using simulation column. Results show that when the mix ratio of coal ash and digested sludge is about 1:1-1.5:1, the permeability coefficient < 10~(-4) cm/s and compressive strength ≥ 50 kPa, MDS can meet the engineering requirements for landfill operation. The optimal conditions of MDS were as follow: mix ratio of coal ash/digested sludge = 1:1, nutrient solution = 0.05 ml/g, thickness of biocover = 400mm, and moisture content of MDS = 40%. The maximum CH_4 oxidation efficiency was 88.6% and the volume flow rate of CH_4 was 0.75 mmol/(kg·d) under the optimal conditions.