Edible Halophytes for Effluent Treatment

I am running a pilot project to test different plants' ability to clean sisal effluent (high BOD and COD, high TDS and salinity 14ppt). The plants either float on the water surface or are put onto raft structures within treatment ponds. Can anyone suggest any plants (preferably indigenous to E Africa) which will tolerate the salt levels and if possible, be palatable to cows and goats or have an alternative economic return? We have to be able to put these onto the rafts so their roots can penetrate the water depth, obviously some plants just become far too big and unstable for this design. Ease of harvesting and handling should also be considered. Thank you in advance for any suggestions.