I operate a high rate anaerobic/aerobic digester (HRAAD) that treats various types of wastewater. The system produces biogas, R2, and R1 water. The treated effluent is used to grow food/fuel/ornamental crops in an advanced hydroponic system. I am looking for a type of grass/sedge that would be suited for riparian zones that can be gasified. My system does have a height constraint of about 3ft. However, I have grown crops that exceed this height constraint by altering lighting regimes and producing rapid flowering/fruiting.
Possibly not applicable, but you might look at the work that Sopper and Kardos did at Penn State with wastewater irrigation in the 1970s and using reed canary grass, cropping on some cycle to remove nutrients. With a little searching on the internet, it should not be too hard to find. It is best to find suitable native species for this, or at least species that are non-invasive. You probably have a hydric soil listing for your area, and it should also have a hydric plant listing. You may also want plants that can withstand flooding if that is the circumstance. That might be helpful. I don't know anything about their ability to withstand gasification. I co-authored a paper I uploaded in researchgate on effects of irrigating sewage on a bottomland (riparian area), but it was well drained for most part and we did not alter plants or try to crop them for nutrient removal.
We have done a fair amount of work with Yellow Nutsedge for contaminant control. It is hardy, and has a good root system. Below is one article:
https://www.researchgate.net/publication/250162350_Uptake_of_lead_and_tungsten_in_Cyperus_esculentus_in_a_small-arms_range_simulation
Article Uptake of lead and tungsten in Cyperus esculentus in a small...
Reed and water hyacinths has also been used in the Philippines and in NASA. But the most practical approach is to select locally thriving grasses with massive root systems. This way, the supply source and environmental setting are no longer and issues. Then test them in the effluents to get their survival and thresholds.
For metal uptake, NASA has experiments on those since the 1980s. Maybe you can ask them.