ABOUT THIS STORY: TCPalm has published two investigations revealing how Florida threatens protected waters by allowing farms to dump tons of only semi-treated human waste on their fields for fertilizer, but the nitrogen and often unneeded phosphorus can run off and feed toxic algae blooms. Today, we explore proposed solutions. It has to go somewhere. Florida must dispose of about 320,000 tons of treated human waste a year. Even so, some scientists and environmentalists say there’s no good reason the state should keep dumping most of it on farms as free fertilizer because it can overload watersheds with toxic algae-spurring nitrogen and phosphorus. “When it comes to biosolids-dumping, there’s just not that legitimate reason other than, ‘Well, it’s cheaper to dump it than it is to do something with it,’ ” said Audubon Florida scientist Paul Gray. “It’s cheaper for (cities), but it hands the bill to society for the cleanup — and the bill is huge.” (Photo: ERIC HASERT/TREASURE COAST NEWSPAPERS) Instead, Florida could treat Class B waste to the higher Class AA standard — meaning nearly no bacteria or heavy metals, but the same amount of nitrogen and phosphorus — and sell it as refined, commercial fertilizer. Or it could ship the waste to states where nutrient-deficient soils need extra nitrogen and phosphorus to grow crops. It’s not that simple, said other experts, such as Nathan Nelson, a former U.S. Department of Agriculture soil scientist who has published several papers on nutrients. “If…