Among the several remediation techniques available for remediation of groundwater, in-situ bioremediation is one of the most economic and eco-friendly technology. Bioremediation of contaminant in the sub-surface domain is a natural attenuation process in which indigenous bacteria consumes the contaminant thereby reducing it into less harmful products like carbon dioxide and water. To accelerate the biodegradation process, an engineered bioremediation process becomes necessary. In a typical engineered in-situ bioremediation system, injection wells are installed at the upstream of contaminated site whereas extraction wells are installed at the downstream end. The injections wells are mainly used to increase the biodegradation rate of contaminants whereas the extraction wells are used to enhance mixing of oxygen and nutrients with the contaminant and further, to contain migration of the plume. Essential nutrients and oxygen required for bioremediation are injected through the injection wells. Furthermore, amongst the various in-situ technologies available for cleanup of heavy metal contaminated sites, phytoremediation has gained immense popularity in the recent years. Phytoremediation is an emerging technology which uses plants and their associated rhizospheric microorganisms to remove, degrade or contain chemical contaminants located in the soil, sediment, groundwater, surface water and in the atmosphere. Phytoextraction, which has emerged as a cost-effective, environment-friendly cleanup technology, is a type of phytoremediation that involves removing heavy metal contaminant from polluted sites using certain plant species called hyper-accumulators. These plants can accumulate large concentrations of targeted metal contaminant in their root-shoot system.
