Valorization of contaminated dredged harbor sediments into artificial aggregates: Metal immobilization, environmental safety, and carbon footprint

Abstract

Dredging is essential for maintaining ports worldwide, but disposing of contaminated dredged sediments (DS) containing toxic metals poses a major environmental challenge. Conventional disposal methods, such as landfilling and ocean disposal, are increasingly restricted by environmental regulations and public concerns. This study offers a sustainable waste management solution by converting hazardous DS into sintered artificial aggregates (AAs) by adding recycled glass waste. AAs produced at 1150 °C with 10 % glass waste addition yield excellent engineering properties, including high compressive strength (>20 MPa), low water absorption (<3%), and minimal porosity (4.67 %), meeting construction material standards. Environmental safety was assessed using leaching tests and the Community Bureau of Reference Sequential Extraction Procedure (BCR-SEP), a standardized method for evaluating metal stability. Both methods confirmed the low leachability of Cu, Zn, Cr, Pb, and Ni under acidic and marine conditions. Pollution toxicity and human health risk indices further demonstrated that AAs are non-toxic and safe for reuse. Although AA production is energy-intensive, its carbon footprint (+0.45  kg CO₂/kg) is offset by the avoided impacts from landfill and ocean disposal. This valorization pathway reduces reliance on natural aggregates, prevents hazardous metal release, and advances circular economy objectives, offering a viable solution for cleaner production and integrated waste management.