Evaluating the environmental impacts of stabilization and solidification technologies for managing hazardous wastes through life cycle assessment: A case study of Hong Kong

Proper management of hazardous materials arouses widespread environmental concerns due to its enormous ecological and health impacts. The development of green stabilization/solidification (S/S) technology for resourceful utilization of hazardous materials, as well as the immobilization of potentially toxic elements is of great scientific interests. Cement-based S/S is often considered a low-cost and highly efficient technology, but the environmental sustainability of a broad spectrum of S/S technologies has yet to be evaluated. Therefore, this study assessed the environmental sustainability of S/S technologies for managing two common types of hazardous wastes, i.e., contaminated marine sediment and municipal solid waste incineration fly ash (MIFA) by using life cycle assessment (LCA). A total of 17 scenarios under three strategies for sediment and two strategies for MIFA S/S technologies were comprehensively evaluated. The LCA results identified the most preferable S/S technology in each strategy. In particular, Scenario 1 (mixture of sediment with a small percentage of ordinary Portland cement and incinerated sewage sludge ash) of Strategy 1 (use as fill materials) would be the preferred option, as it reduces about 54% and 70% global warming potential compared to those of Scenarios 2 and 3, respectively. This is the first initiative for evaluating the environmental impacts of a wide range of recently developed S/S technologies using green/alternative binders for diverting hazardous wastes from disposal. The results can serve as a decision support for the practical application of the environmentally friendly S/S technology for sustainable remediation.