Contaminated Sediments Used Successfully in Safe Construction Material

A consortium of Scandinavian companies, researchers, and port officials have discovered what they say is a safe and cost-effective way to use contaminated port and river sediments for construction. Many rivers and port areas around the world contain soils and sediments polluted by dangerous chemicals and carcinogens such as PCBs, cadmium, lead, and mercury. The Swedish-Norwegian consortium says it has developed a technique in which the contaminated sediments are dredged and then mixed with cement and slag from the steel-making process. The toxic heavy metals in the sediments bind chemically with materials in the slag, rendering the concrete-like substance stable so that toxins do not leach into the soil or water. Led by Merox, a subsidiary of Swedish steelmaker, Svensk Stal, the team successfully dredged 500 cubic meters of soft sediment and mixed it with the slag and cement. The material was then placed on sand, where studies showed that the contaminants did not spread to the environment. Officials say the new technique — which could be used to build roads, port loading zones, and buildings — is less expensive and safer than moving sediments to landfills or dumping them at sea.