Sustainable bioremediation and reuse of heavy metal-contaminated dredged sediments using Bacillus subtilis

Abstract

Urbanization has led to heavy metal contamination of dredged sediments, posing severe environmental and health risks. This study investigated the efficacy of Bacillus subtilis-bioremediation and reuse Heavy Metal contaminated sediment as construction material. Recognizing the limitations of conventional calcium chloride, alternative calcium sources for enhanced remediation were explored. The results demonstrate that utilizing calcium hydroxide (0.625 M) as a cementing reagent resulted in optimal compressive strength while minimizing heavy metal leaching. A substantial reduction in leachability: 97.8% for cadmium, 92% for nickel, and 98% for zinc, was observed as determined by USEPA Method 1311. Sequential extraction procedure analysis revealed the effective immobilization of heavy metals within the sediment matrix, primarily through their conversion to metal carbonates and their association with organic matter. This eco-friendly bioremediation approach, combining bacterial activity with sustainable cement stabilization, presents a promising remediation strategy for contaminated dredged sediments, enabling the safe reuse in engineering applications.