Why the Fertilizer Industry Could Use a Little Biosolids

Approximately ten years ago, testing was performed at a traditional ammonium sulfate fertilizer plant by substituting dewatered wastewater biosolids for the water that was used to control reaction temperatures. The result was a high nitrogen product, which exhibited slow-release properties when used on citrus, field and turf crops. Over 115,000 metric tons were manufactured and successfully used from this facility. Over the last several years, VitAg Corporation has refined the manufacturing process and expects to commence construction in 2013 of the first purposefully designed organically-modified ammonium sulfate fertilizer manufacturing facility.In the VitAg patented process, biosolids are first reacted in a mechanically agitated hydrolysis vessel utilizing concentrated sulfuric acid. This acidified mix is then transferred under pressure to a second mechanically agitated hydrolysis vessel and mixed with anhydrous ammonia. The resultant exothermic chemical reactions cause the ammoniation vessel contents to heat to a controlled temperature in excess of 320°F. The acidification and ammoniation reactions destroy all microorganisms. This “melt” is sprayed into a granulator, the resulting granules are then conveyed to a dryer, and finally to product sizing and cooling. This process results in the production of a dry, uniform and hard fertilizer granule.Approximately 14 percent of this fertilizer's ingredients are organic, the balance is inorganic. The typical nutrient content is 16-0-2-17-3-14 (N-P-K-S-Fe-Organic). This product meets standards for agronomic commercial fertilizer use and is widely effective in many commercial crop application strategies. The product is extremely dry (99.5 percent solids) which enhances its ability to compete with both specialty and commodity fertilizers. As a result of the biosolids component being subjected to high temperatures and pressures, the product meets or exceeds the highest level of US Environmental Protection classification for disinfection, i.e., Class A.