Innovative research has resulted in the removal of 90% of the phosphorus from animal feed, reducing the possible creation of dead zones in the natural environment.
Commonly used as agricultural feed, dried distiller’s grains with solubles (DDGS) is produced in the corn ethanol process. DDGS often contain more phosphorus than agricultural animals are capable of adsorbing and far more than they need. The excess phosphorus is left in the manure of the animal, which then drains into the watershed. This excess phosphorus can promote algae production which can lead to large ‘dead zones’, like those found in the Gulf of Mexico.
A new study conducted at the University of Illinois, USA, examines the most efficient way to recover excess phosphorus as a co-product. The excess nutrient could then be used to fertilize the land used to grow foods such as corn and soybeans.
“A lot of phosphorus is in the corn itself. When corn is processed, you get different products. Some of it is fed in animal diets, which already contain plenty of phosphorus.
“So, the additional phosphorus comes out in the manure and leaches into the groundwater,” says Vijay Singh, the study’s co-author. Singh is professor of agricultural and biological engineering and director of the Integrated Bioprocessing Research Laboratory (IBRL) at University of Illinois.
“We asked, can we do something in the process itself to recover this phosphorus, and put it back on the land as fertilizer? It’s like a circular economy,” Singh adds.
Recovering 90% of the phosphorus
As part of a multi-pronged project, this study spans several departments at the College of Agricultural, Consumer and Environmental Sciences at University of Illinois.
Ankita Juneja, postdoctoral research associate in the Department of Agricultural and Biological Engineering, said: “We started with a model and estimated the flow of phosphorous in the entire diagrammed plant. Then we determined where the maximum concentration of phosphorus occurs, which will help us recover it economically.”
According to this study, the researchers were able to recover up to 90% of the phosphorus by increasing the alkalinity of thin stillage, adding calcium chloride and then stirring the product in a continuous stir reactor.
Juneja continued: “the animal food requirement of phosphorus in DDGS is 3 to 4 milligrams per gram of DDGS. Previously, the DDGS had about 9 to 10 milligrams per gram. So, the rest was all excess, which would get into the manure. We were able to reduce it down to 3.25 milligrams per gram, which is in the range of what the animals actually need.”
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