I-Corps: Vacuum Stripping and Absorption to Recover Ammonia from Wastewater

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The broader impact of this I-Corps project is the development of technology that lowers the operating costs for treatment of ammonia-rich wastewater and generates revenues by turning the removed ammonia into a sellable nitrogen fertilizer. The ever-increasing number of anaerobic digestion systems at municipal wastewater treatment facilities and concentrated animal feeding operations are shifting the paradigm of wastewater treatment from contaminant removal to recovery of bioenergy in the form of biogas, nutrients, and water. The technology may be fabricated in different sizes of modules, providing operational ease and flexibility of scaling. The ammonia extracted from wastewater also has the potential to be used for production of certified organic fertilizers. This I-Corps project is based on the development of technology termed vacuum stripping and absorption (VaSA) for recovering ammonia in wastewater with high purity. VaSA couples vacuum thermal stripping and acid absorption to pull ammonia out of ammonia-rich wastewater to form ammonium sulfate granules. Moreover, recovering ammonia in wastewater may be a sustainable alternative to the energy-intensive Haber-Bosch process for ammonia synthesis. Using a weak vacuum, the boiling point is reduced from 100 to 65 degrees C for safe, efficient stripping of ammonia without the need for pretreatment. It has been recognized as the most practical method for ammonia recovery and fills the gap for an efficient, versatile, and scalable ammonia recovery technology. When VaSA is incorporated into anaerobic digestion systems, it avoids ammonia inhibition to methane-producing microorganisms, thus enabling stable anaerobic digestion at a higher loading rate. The vacuum-assisted low-temperature thermal treatment in the VaSA process enhances solids solubilization and biodegradability of digestate, further increasing methane production as stripped digestate is returned to the digesters. When employing VaSA to recover ammonia from digester effluent, it improves the ability to separate solids from digester effluent and upgrades the from Class B biosolids to Class A for unrestricted land application.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.