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When separated soil (SS) generated from the Great East Japan Earthquake, which contains woodchips and others (WC), is utilized as ground material, microorganisms decompose the organic carbon in WC, and oxygen is consumed in the process. This reaction results in forming an anaerobic zone and generating methane gas. To effectively utilize SS as ground material, it is necessary to prevent anaerobic zone formation to ensure safety. This study clarified the relationship between WC content and the concentration of leached organic carbon (TOC) and the relationship between TOC concentration in the eluate and the oxygen consumption rate were clarified. We obtained the relationship between WC content and the extent of anaerobic zone formation from the results,. The anaerobic zone is formed below the oxygen penetration depth (LO2). LO2 rapidly decreases as the WC weight ratio increases from 0 to 1 w%, and LO2 is almost constant, i.e., around 1 to 2 m above 1 w% WC weight ratio. An increase in WC weight ratio does not significantly decrease LO2 determined by the aerobic decomposition of the solution. From the above, contamination with WC should be limited to 1 w% or less to prevent the formation of an anaerobic zone. If SS has WC above 1 w%, it is required to put a ventilating layer such as crushed stone every few meters or the other countermeasures when SS is utilized as ground material., Soils and Foundations, 62 (2), art. no. 101109; 2022

Landfilling municipal solid waste incineration (MSWI) residue alkalizes the waste layer, causing a subsequent decrease in microbial activity and a delay in the decomposition of organic matter. In this study, efficiencies of neutralization of the leachate and organic matter decomposition in the waste layer in a column filled with MSWI residue using aeration and compost addition were evaluated. Total organic carbon (TOC) reduction in the waste layer is large at high oxygen flow rate (OFR). To effectively accelerate TOC reduction in the waste layer to which compost was added, a high OFR exceeding that by natural ventilation was required. At day 65, the pH of the leachate when OFR was above 102 mol-O2/(day·m3) was lower than that when OFR was below 101 mol-O2/(day·m3). At the same OFR, the pH of waste sample was lower than that of waste sample with compost. Although leachate neutralization could be affected by compost addition, TOC reduction in the waste layer became rather small. It is possible that humic substances in compost prevent the decomposition of TOC in MSWI residue., identifier:Journal of Environmental Sciences, 25(1), pp.53-58; 2013