The acceleration degradation processes of different aged refuses with the forced aeration for landfill reclamation

Abstract

Forced aeration is one of the promising ways to accelerate landfill reclamation, and understanding the relation between aeration rates and waste properties is the prerequisite to implementing forced aeration under the target of energy saving and carbon reduction. In this work, landfill reclamation processes with forced aeration were simulated using aged refuses (ARs) of 1, 4, 7, 10, and 13 disposal years, and the potential of field application was also investigated based on a field project, to identify the degradation rate of organic components, the O₂ consumption efficiency and their correlations to microbes. It was found that the removal rate of organic matter declined from 20.3% (AR₁) to 12.6% (AR₁₃), and that biodegradable matter (BDM) decreased from 5.2% to 2.4% at the set aeration rate of 0.12 L O₂/kg waste (Dry Matter, DM)/day. A linear relationship between the degradation rate constant (K) of BDM and disposal age (x) was established: K = − 0.0002193x + 0.0091 (R² = 0.854), suggesting that BDM might be a suitable indicator to reflect the stabilization of ARs. The cellulose/lignin ratio decrease rate for AR₁ (18.3%) was much higher than that for AR₁₃ (3.1%), while the corresponding humic-acid/fulvic-acid ratio increased from 1.44 to 2.16. The dominant bacteria shifted from Corynebacterium (9.2%), Acinetobacter (6.6%), and Fermentimonas (6.5%), genes related to the decompose of biodegradable organics, to Stenotrophomonas (10.2%) and Clostridiales (3.7%), which were associated with humification. The aeration efficiencies of lab-scale tests were in the range of 5.4–11.8 g BDM/L O₂ for ARs with disposal ages of 1–13 years, and in situ landfill reclamation, ARs with disposal ages of 10–18 years were around 1.9–8.8 g BDM/L O₂, as the disposal age decreased. The increased discrepancy was observed in ARs at the lab-scale and field scale, indicating that the forced aeration rate should be adjusted based on ARs and the unit compartment combined, to reduce the operation cost.