The harvesting step collects both the algal turf and the pollutants, nutrients or other undesirable species precipitated thereon, thus removing {TAIL ~ the species} from {HEAD ~ the water} 
The harvesting step collects both the algal turf and the pollutants , nutrients or other undesirable species precipitated thereon , thus removing { TAIL ~ the species } from { HEAD ~ the water }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD