A hybrid phytoremediation system for contaminants in groundwater

Impacted groundwater at hazardous waste release sites often contain mixtures of contaminants. It can be relatively easy to treat some compounds ex situ. However, mixtures of some compounds can be difficult to treat. A method to extract and treat complex mixtures of contaminants of concern using phytotechnology is proposed in this paper. A specific case study is described wherein a hybrid phytoremediation system is compared and contrasted with conventional groundwater and phytoremediation technologies. Nitrate is used as an exemplar co-contaminant since nitrate contamination is (1) widespread in the United States, and (2) difficult and expensive to treat. The approach involves using contaminated groundwater as a source of irrigation water for a phytoremediation grove. Groundwater would be extracted using conventional groundwater extraction methods. Groundwater then would be pumped to multiple irrigation zones under the control of an autonomous irrigation system. Each zone would consist of a number of trees. The root system for each tree would be modified to function as a confined treatment cell that facilitates contaminated water uptake. The irrigation controller would optimize the amount of groundwater that can be extracted and treated while preventing surface water runoff away from the phyto component.