The broader impact of this Small Business Innovation Research (SBIR) Phase I project lies in transforming a source of water pollution into a renewable source of fertilizer, which will reduce dependence on non-renewable resources for both wastewater treatment and fertilizer production. Rather than combining all domestic wastewater into one dilute stream, this project inverts the paradigm by separating out and recycling the largest source of nutrient pollution: urine. Special toilets with a separate drain at the front of the bowl direct urine through dedicated plumbing to a compact building-scale processor, which converts it into a purified liquid fertilizer. This technology will have immediate utility in sensitive watersheds where regulations require landowners to remove nitrogen from wastewater using expensive septic systems upgrades. Urine diversion could be an alternative to such upgrades, at a lower cost, with less ongoing energy demand, and with the added benefit of producing fertilizer as an end product. When the technology is more mature, it could be applied in areas served by central sewers, as a decentralized nutrient recovery strategy. The technology will create jobs in installation and service, reduce the load on wastewater treatment plants, help restore our waterways, and yield a clean, domestically-produced fertilizer for use in agriculture.
This SBIR Phase I project will advance translation of a building-scale urine collection and treatment system is paired with commercially-available urine-diverting toilet fixtures to create an advanced resource recovery system with a conventional bathroom experience. The system employs a four-step process: acidification, pasteurization, freeze concentration, and charcoal filtration. The combined effect of these four steps includes volume reduction, odor control, nutrient stabilization, and removal of contaminants such as pathogens and pharmaceutical residues. The project has two main goals: 1) measuring the energy requirements of the treatment steps, using these data to optimize the freeze concentration step; and 2) testing the performance during ongoing operation to identify and address problems relating to biofilm or mineral scale formation. The proposed freeze concentrator uses a proprietary technology that is mechanically simple, energy-efficient, and scalable to a small physical footprint. In addition to urine diversion, this device could have useful applications in other fields requiring a small, mechanically simple, and inexpensive dewatering system. The four processing subsystems will be designed using thermal and hydraulic modeling, and tested using real urine from a source-separating toilet. Subsystems will be tested individually for performance and energy efficiency, and then together as an integrated system.
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.
