Study of leaching scenarios for the application of incineration bottom ash and marine clay for land reclamation

摘要

Green technology for utilizing incineration bottom ash (IBA) and marine clay (MC) using chemical-physical combined method (CPCM) for land reclamation has been proposed for Singapore. The formed filled material was termed as MC-IBA matrix. This proposed technology is an attractive proposition for solving twin problems of finding space for disposal of incineration ash and finding sustainable and low-cost resource as filled material for reclamation. Modeling simulation experiments of land reclamation employing this technology were conducted using the in-house three-dimensional consolidation cells to assess its geotechnical and environmental feasibility. The shear strength of MC-IBA matrix was found to improve significantly under the CPCM treatment and attained 26–30?kPa within around 2?wk. It demonstrated the geotechnical effectiveness of the technology. From environmental aspect, heavy metal contamination through any possible on-site effluents discharge must be considered and evaluated. Effluent generations through self-weight consolidation process (SWC) and vacuum pre-loading (VP) during reclamation construction period were studied, including those of IBA storage and transportation period were simulated. The results were analyzed and compared with the relevant regulation standards. It was found that metal concentrations of all the effluents met the public sewer discharge standard. In regards to the allowable limits for trade effluent discharge into watercourse, VP effluent complied with the standard, while SWC effluent generated during construction period and soaked rainwater generated during IBA transportation and storage period failed to meet the requirements as Cu and Ba concentrations were higher than the limits. As such, an inorganic coagulant was proposed to remove excess Cu and Ba from effluent.