Grantee Research Project Results
Final Report: Electrodialytic Nutrient Recovery for traditional and advanced OWTS effluent
EPA Contract Number: 68HERC21C0046Title: 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)
Description:
Nutrient pollution contributes to global water quality issues in the form of eutrophication, which leads to algal blooms and dead zones due to oxygen depletion, as well as public health issues such as methemoglobinemia. Meanwhile, these same nutrients are necessary for agricultural production, and their supply is in increasing demand while producing that supply requires a substantial amount of energy (nitrogen) or is a finite resource (phosphorus). A major source of nutrient pollution is inadequately treated sewage, in particular, from onsite wastewater treatment systems (OWTSs). The US and global populations reliant on OWTSs are large and growing, and the EPA estimates that over 2.6 million existing OWTSs in the US may require technical improvements for nutrient management (particularly nitrogen) due to their location in nitrogen-sensitive watersheds.
Triangle Environmental Health Initiative (TE) developed a concept to solve this challenge - a bolt-on technology for existing OWTS products that can separate nutrients from their effluents - as a retrofit to systems currently in the ground or as an integration for new installations. TE's innovation is Electrodialytic Nutrient Recovery (ENR) which removes nutrients from wastewater streams, creating separate nutrient-depleted and nutrient-rich steams. The nutrient-depleted stream is safe for environmental release while the nutrient-rich stream can be reused as a fertilizer. With this approach, TE's technology prevents environmental nutrient pollution in a method that recovers these same nutrients for safe reuse. This feature of creating nutrient-rich and nutrient-depleted streams is unique to TE's technology and allows for reuse opportunities, whereas existing nutrient management approaches in OWTSs do not allow reuse. However, where reuse is not viable, the nutrient stream can be recycled through the front-end treatment process of the existing OWTS for much more efficient nutrient removal compared to exiting products. With TE's ENR technology, the final effluents from existing OWTS products can meet new and upcoming nutrient standards that are currently unattainable for most products on the market.
TE's EPA Phase I SBIR efforts proved the concept of the technology and its application to OWTS effluents. The purpose of EPA Phase II SBIR research was to build on Phase I success by demonstrating technology performance at full-scale with operational OWTSs in the field. The key objectives were to determine if bench-scale performance was maintained when scaling up, if performance could be sustained over longer periods, if operation and maintenance was viable for decentralized applications, and if the technology had commercial viability based on value-add and manufacturability.
Summary/Accomplishments (Outputs/Outcomes):
In Phase I testing, TE examined the nutrient separation efficiency of a small, lab-scale electrodialysis cell for the treatment of real onsite wastewater. The experiments demonstrated high ion (e.g., NO3-, NH4+, PO43-) removal and concentration performance that was consistently maintained over three months of operation with real septage. Based on these results, Phase II efforts pursued three primary tasks: (1) piloting full-scale prototypes in real-world applications that would be representative of key markets, (2) advancing our understanding of long-term operation and maintenance, and (3) collaborating with a commercial partner and industry leader, to further baseline manufacturing capabilities and bring the technology to market.
In the first task, TE purchased two full-scale off-the-shelf electrodialysis prototypes and compared their performance to their previous bench-scale prototype with representative wastewaters in our lab to investigate scaling impacts and key design factors between the different prototypes which would inform future custom units. While also in the lab, TE tested different operating scenarios for preventative anti-fouling measures which continued to prevent fouling from setting in while increasing uptime. Further, TE performed stress-testing of the bench-scale prototype with peak-concentrations of nutrients in the feed wastewater stream by continually recycling the concentrate stream back to the feed stream. Finally, TE examined different cleaning methods of the initial bench-scale prototype which had seen several months of operation with representative wastewaters, elucidating the most beneficial cleaning methods which pointed to the primary modes of fouling. The target for reasonable operation and maintenance of this decentralized technology is a maximum cleaning frequency of 1-2 times per year with readily-available and low-cost solutions. These studies supported that protocol is viable.
Based on results from the above lab activities, TE initiated piloting with an off-the-shelf electrodialysis prototype at their commercial partner's testing facility. The technology was installed to treat the effluent leaving an operational system and treated 200-250 gallons of this effluent per day for 10 months. This system was much higher in organic, solid, and nutrient concentrations than would be expected from a typical domestic OWTS. These high-strength wastewaters created challenging but instructive conditions to test the durability and robustness of the technology in a "worst-case" setting. As such, this experience pushed the technology to its limit and displayed the primary potential operational and maintenance challenges for long-term performance. Automated monitoring of key parameters, including power consumption and conductivity, as well as lab testing for wastewater characteristics was routinely conducted to evaluate technology performance in removing and concentrating contaminants. After four months of operation, initial results informed operational strategies to increase system uptime and longevity which were implemented for the final six months of pilot testing with success. Despite operational challenges from the high-strength wastewater feed, the technology generally maintained high nutrient separation performance, achieving nitrogen removal efficiencies between 65-99%, throughout 10 months of operation. The discoveries made during piloting led to the design of a much stronger treatment process and product.
TE executed most of these tasks in collaboration with a commercial partner from the OWTS industry. By the end of Phase II, TE was able to utilize the commercial partner's manufacturing capabilities to produce a custom unit, the design of which was informed by the long-term operation, observation, and optimization of the off-the-shelf prototype. This custom unit was created using the commercial partner's facilities by manufacturing some key components from raw materials and to assemble other components procured directly from other manufacturers. These components purchased from other manufacturers had been identified by testing several varieties and determining which was best for this market application. The "pre-manufactured" unit was created at vastly reduced cost and weight compared to the off-the-shelf prototypes purchased at the start of this project. The final product is soon to be deployed at two field testing sites at homes utilizing the commercial partner's existing system for six months of continuous testing, after which TE will endeavor to work with the commercial partner to bring the system to the marketplace.
Conclusions:
Based on the results of the Phase II piloting initiative, the technology shows promise as a viable solution for nutrient separation in advanced wastewater treatment processes. From lab-scale testing with three different prototypes simulating different conditions to 10 months of full-scale piloting with actual OWTS wastewaters, the system has shown promise in terms of scalability and ease of operation. With further development and optimization, TE anticipates that the device could be implemented in markets ranging from residential homes to commercial buildings, providing a sustainable, cost-effective, and multi-purpose method for the separation of nutrients from waste streams for reuse or, if necessary, improved removal.
In addition to confidence in technical feasibility, TE and their commercial partner have strong confidence in commercial viability, particularly due to the commercial partner's already-developed engineering and manufacturing experience with the technology which will allow for rapid uptake into their product development program. The commercialization plan at that time is to demonstrate system performance at two locations for six months. The commercial partner will lead monitoring and evaluation efforts at one location while TE leads those efforts at the other. Pending successful performance, a licensing agreement will be arranged based on the IP developed around the technology wherein TE will earn sales royalties on product rollout through the commercial partner's manufacturing and distribution channels. During the piloting period, the commercial partner will determine which certifications (national vs. key states) are most strategic for commercial roll-out and initiate the certification process after executing the licensing agreement.
SBIR Phase I:
Electrodialytic Nutrient Recovery From Wastewater | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.