Fish Wastewater Creates New Variety of Fertilizer
Fish wastewater contains nutrients that can replace fertilizer.Scientists and agriculturalists have used animal by-products such as bird and cow manure as fertilizer and energy sources for thousands of years.The technology and the system by which we obtain the by-products has changed to become more cost effective."When fish eat, they retain about 40 percent of the nutrients in the food," said Jesse Chappell, associate professor in the Department of Fisheries and Allied Aquacultures.The other 60 percent is excreted in the form of urine and feces.In all systems, the water must be treated or the toxins produced by the urine and feces will kill the fish.In most fisheries, the tanks the fish grow in have a biofiltration apparatus, an expensive and often complicated system that removes toxins from the water, Chappell said.Chappell and his team of researchers, including horticulture professor Jeff Sibley, found a way to eliminate the biofilter.Instead of treating the water, Chappell's system removes 1 to 5 percent of the water in the tank, depending on the biomass of the fish and replaces it with new water.That small percentage of fish wastewater is then used as a fertilizer for some plants.
