Development of a Zero-Valent Iron-Based In-situ Reactive Zones Technique for Remediation of Contaminated Groundwater
ZHENG Xilai;TANG Fenglin;XIN Jia;HAN Jun;Key Laboratory of Ocean Environment and Ecology,Ministry of Education,Ocean University of China;
A zero-valent iron( ZVI)-based in-situ reduction zone( IRZ) is a promising technique and an effective alternative to PRB( permeable reactive barrier) for remediation of contaminated groundwater. IRZ has received significant attention due to its low engineering cost,simple construction,fewer disturbances to the environment and high efficiency in degrading a broad range of contaminants found in aquifer systems. Based on a comprehensive literature review,it was determined that remediation efficiency is influenced by the physical and chemical properties of the ZVI,hydrogeochemical characteristics and contamination situation of the site. Developments in several key aspects are helpful for understanding its advantages and uncertainties. The areas include reactivity with a wide spectrum of organic and inorganic contaminants,methods to enhance the colloidal stability and mobility of ZVIs in subsurface environments,eco-toxicological impact of ZVIs and engineering measures. However,some problems exist when using the technique: 1) poor mobilization of injected ZVIs in the aquifer; the placement of injected ZVIs during groundwater remediation monitored by indirect methods,such as Fe~(2+) and pH; 2)reduced reactivity of ZVIs caused by a series of corrosion reactions and precipitated amorphous and crystalline iron corrosion products; and3) insufficient knowledge about potential biological and environmental effects. Given that,more efforts should be made to address the issues of surface modification,reaction mechanism,passivation behavior,longevity assessment,passivation rejuvenation and prevention.Moreover,the fate,transformation and exposure paths should be revealed,and ecosystem assessment should be established. For engineering applications,the hydrogeological conditions of the contaminated site should be pre-evaluated,and an advanced monitoring technical system should be developed to follow the fate of injected ZVIs particles and their corrosion products.
【CateGory Index】： X523
【CateGory Index】： X523