Leaching assessment of matrix land reclamation material

Abstract

A green strategy has been proposed by stabilising incineration bottom ash (IBA) waste and marine clay (MC) waste as land reclamation material, termed MC-IBA matrix. However, the reuse of IBA may increase the potential threats to the environment since IBA contains heavy metals. Heavy metal leaching depends on the interplay of various physical and chemical factors such as size, shape and porosity of the particles, temperature, pH, aging and degradation of material and control mechanism and so on. In this paper, the leaching process against pH and time was studied as a necessary environmental assessment. Three laboratory leaching tests were employed to characterise the leaching: pH-dependent test (CEN/TS 14429), availability test (NEN 7371) and diffusion test (NEN 7347). The shear strength development of the MC-IBA matrix was also determined. Results indicated that (1) the shear strength of the MC-IBA matrix presented a great increase during curing time; (2) pH played a significant role in heavy metal leaching; (3) in long-term leaching, the heavy metal release of the MC-IBA matrix was at minimum level and it was reduced over time; (4) the cumulative heavy metal leaching of the MC-IBA matrix over 64 d was below the maximum leaching threshold.