Electrodialytic Nutrient Recovery for traditional and advanced OWTS effluent

EPA Contract Number: 68HERC21C0046
Title: Electrodialytic Nutrient Recovery for traditional and advanced OWTS effluent
Investigators: Forbis-Stokes, Aaron
Small Business: Triangle Environmental Health Initiative
EPA Contact: Richards, April
Phase: II
Project Period: April 1, 2021 through March 31, 2023
Project Amount: $400,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2021) Recipients Lists
Research Category: SBIR - Water , Small Business Innovation Research (SBIR)


Electrodialytic nutrient recovery (ENR) is a bolt-on technology for existing products in the onsite wastewater treatment system (OWTS) market. ENR is set apart from competitive technologies in that it can meet or exceed strict regulatory standards for nutrient removal without biological processes or added chemicals. The United States has a growing population reliant on OWTS products, and many regions are increasingly experiencing negative environmental impacts due to nutrient contamination from OWTSs. At least 10% of new OWTS installations require advanced treatment technologies, and 2.6 million existing systems may require upgrades due to their location in nutrient-sensitive watersheds. Existing advanced OWTS technologies can meet local standards, but they are expensive, require a large footprint, typically only address nitrogen and not phosphorus, and have reached a performance boundary (≤75% N removal or 12-25 mg N L-1 in effluent). Few retrofit options exist for in-ground systems, and these are also large and expensive. ENR provides two market applications: (1) Retrofits of under-performing in-ground systems to meet new nutrient regulations and (2) Incorporation into advanced OWTS products to expand their market reach to regions with the strictest requirements (e.g. <10 mg N L-1 in Chesapeake Bay).

ENR utilizes membranes to capture ammonium (NH4+), nitrate (NO3-), and phosphate (PO43-) ions in a concentrated stream with a proprietary electrochemical process to mitigate organic fouling. The concentrated nutrient-rich stream is suitable for resource recovery and the nutrient-stripped stream is safe for discharge. Phase I testing established the ENR proof-of-concept with a lab-scale prototype treating effluent from both a conventional septic and an advanced OWTS to ≤10 mg L-1 (from ~60 mg NH3-N L-1 and 35 mg PO4-P L-1 in the conventional and ~30 mg L-1 NO3-N and PO4-P in the advanced OWTS) without loss in performance over 7 days of continuous operation. Phase II testing will focus on full-scale ENR prototypes (15 gallon footprint for 500 gallon per day capacity) applied to in-field conventional and advanced OWTS in partnership with industry leaders engaged during Phase I.

Market engagement indicates that the highest demand among end users would be residential homeowners in nutrient-sensitive regions with OTWS. Industry leaders have indicated ENR could support advancement of septage regulations, if Phase I cost and performance metrics can be replicated at scale. Triangle Environmental's targeted direct customers are waste treatment companies with production, marketing, and distribution capabilities. The primary focus are industry leaders with national reach and in-house product development capabilities.

SBIR Phase I:

Electrodialytic Nutrient Recovery From Wastewater  | Final Report