A new sustainable technique to remediate heavy metals contamination In Groundwater: in-situ precipitation

摘要

Groundwater contamination with heavy metals is a recurring major problem for mining and metallurgical sector worldwide. Expensive and non sustainable remedial methods such as Pump&Treat are currently applied. An extensive pilot program is under execution to design an in-situ remediation system (metals precipitation) for historic groundwater contamination with heavy metals underneath three non-ferrous industrial sites. This program is funded by EU LIFE program. Tracers tests, data acquisition and groundwater & hydrochemical models were performed to simulate, monitor and optimize the injection design. Batch and column tests were performed to select an economic and efficient electron donor. Laboratory tests concluded that biochemical precipitation, inducing sulphate reduction and subsequent metal sulphide precipitation, is a feasible option. Three pilot tests were started in 2007. 6-monthly injections were performed and resulted in a distinct decrease of metals concentrations as well as lowered sulphate concentrations. In situ bioprecipitation has been successfully demonstrated by field tests. However, to ensure a sustainable process, the stability of the formed precipitates is currently under study. This research project could present an economical and sustainable technique to reduce footprint and to remediate metal contaminated aquifer from mining & metal operation sectors, as well as historical industrial contamination.