Remediation of contaminated sediment originating from wastewater at harbor areas using slaked lime – fly ash – cement mixture

Abstract Widespread pollutants from wastewater are serious threats to the ecosystem and aquatic environments in harbor areas. However, very few methods are available for the remediation of contaminated sediments. Herein we examine an in-situ method using a new material, known as slaked lime–fly ash–cement mixture (SFCM), that removes phosphate and hydrogen sulfide from contaminated sediments. For this purpose, we analyze the effects of SFCM based on mesocosm experiments. After the application of SFCM, the hydrogen sulfide concentration significantly decreased from 130 to nearly 0 mg L−1 and remained at this level for nearly six months. The phosphate concentration in the sediment decreased to its lowest level at 5 mg L−1 and decreased for the remainder of the experimental period. These results demonstrate the successful removal of phosphate and hydrogen sulfide by applying SFCM. Results also showed that the pH remained between 8 and 8.2 after experimentation, which is similar to seawater pH. Based on these results, we conclude that SFCM is an effective material to mitigate contaminated coastal sediment in harbor areas.