SBIR Phase II: Sanitation for the circular economy: Treating high strength wastewater for nutrient and water recovery

The broader impact of this Small Business Innovation Research (SBIR) Phase II project lies in transforming a ubiquitous source of water pollution into a renewable source of fertilizer, while facilitating onsite treatment and reuse of recycled greywater. This technological solution is intended to conserve precious drinking water supplies and 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 separates and recycles the largest source of nutrient pollution: toilet waste. Source-separating bathroom fixtures (including waterless urinals, urine-diverting toilets, and vacuum-flush toilets) direct the waste through dedicated plumbing to a compact building-scale processor, which converts it into a purified liquid fertilizer.

This technology may have immediate utility in sensitive watersheds where regulations require landowners to remove nitrogen from wastewater, and in urban settings where municipalities are subsidizing or mandating distributed wastewater treatment because their central wastewater treatment facilities have reached or exceeded their design capacity. The technology may create jobs in installation and service, reduce loads on wastewater treatment plants, restore waterways, and yield clean, domestically-produced fertilizer for use in agriculture.

This SBIR Phase II project focuses on developing a building-scale, high-strength, wastewater treatment system paired with source-separating bathroom fixtures to result in a resource recovery system. Nutrients are recovered from the influent wastewater through a four-stage treatment train that includes: (1) acidification to minimize pipe occlusion, (2) freeze concentration to reduce volume, (3) pasteurization to destroy pathogens, and (4) filtration to reduce the concentration of pharmaceuticals and other organic compounds.

The objective of this research project is to develop this technology to the point where it can be installed in a building and is capable of capturing greater than 90% of nutrients from 600 liters of wastewater per day with minimal energy inputs. This goal will require increasing the working volume of the current freeze concentrator, optimizing the energy usage of each element in the treatment train, packaging each element so that they are durable, readily installable, and easily maintained, and developing a fully automated control system.

Each element of the treatment train will be tested individually to demonstrate that a consistent, concentrated, sanitized fertilizer can be produced from high-strength wastewater while decreasing building water demand.

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.