Groundwater remediation using permeable reactive barrier technology

A Permeable Reactive Barrier (PRB) represents a valid and sustainable in situ groundwater remediation technology. It consists of a diaphragm wall, filled with a reactive medium and placed across the flow path of the contaminated groundwater in order to intercept the contaminants. A PRB does not require energy for, it requires the removal of modest volumes of soil, it does not present problems of visual impact and allows the use of the contaminated site during remediation. Monitoring performed on fullscale PRB, composed of zero valent iron (ZVI) as reactive medium, showed that, despite the considerable reactivity, ZVI is not able to maintain its hydraulic conductivity over a long period of time. The objective of the present work was to improve the hydraulic behaviour of the ZVI, by mixing this material with lapillus, a reactive medium of volcanic origin, sustainable for the environment and readily available. Experimental studies, conducted through batch and column tests, have shown that lapillus is reactive towards the tested contaminants, i.e. nickel and zinc, whose presence seriously threatens the quality of aquifers.