Grantee Research Project Results
2023 Progress Report: Electro-Assisted Wastewater Nutrient Recovery
EPA Grant Number: SV840417Title: Electro-Assisted Wastewater Nutrient Recovery
Investigators: Tarpeh, William A , Dong, Hang , Kogler, Anna , Clark, Brandon , Chow, William , Apraku, Edward
Institution: Stanford University
EPA Project Officer: Page, Angela
Phase: II
Project Period: February 1, 2023 through January 31, 2025
Project Period Covered by this Report: February 1, 2023 through January 31,2024
Project Amount: $100,000
RFA: 17th Annual P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2022) Recipients Lists
Research Category: P3 Awards
Objective:
Nitrogen (N) and phosphorus (P) are critical elements for human society and environmental ecosystems. Both elements exist in multiple forms as pollutants in some settings and valuable products in others. Anthropogenic influences on the N and P cycles have led to harmful algal blooms, unsustainable energy consumption, and runaway greenhouse gas emissions. Meanwhile, both N and P are essential macronutrients in fertilizers that are currently obtained via energy-intensive N-fixation (Haber-Bosch process that consumes ~ 1% global energy to convert N2 to NH3) and unsustainable P mining. Agricultural fertilizer runoff discharges excessive N and P into aquatic systems, causing harmful algal blooms. The primary technical challenge we address is engineering selective separations to capture and recover dilute N and P from polluted waters (wastewater plant effluent and impaired surface waters). We address this technical challenge with selective adsorbents because they can capture dilute pollutants and are amenable to regeneration that replaces chemical inputs with electricity to recover nutrients on site, particularly in remote, rural, and disadvantaged communities. In addition to advancing recovery technologies, we plan to leverage this project as an educational tool by involving undergraduate researchers in laboratory investigations, undergraduate students in classroom demonstrations, and the broader public (with an emphasis on underrepresented minority audiences) in field-scale validation and facility tours. Integrating our research, education, and outreach efforts will inspire future environmental researchers; enhance classroom education with real-world exposure to wastewater treatment; and enhance sustainability awareness among diverse stakeholders.
Progress Summary:
The overarching goal of our proposed work in Phase II is to advance the nutrient-selective adsorbent and the electro-assisted regeneration (developed in Phase I) into an intensified self-sustaining device for nutrient capture and recovery. We concentrate on process intensification, or combining multiple unit processes to minimize inputs and emissions, to further advance our mission of realizing resource-efficient water treatment that benefits people, prosperity, and the planet. We have demonstrated electrochemical regeneration of Zn-WAC resins and HAIX resins in intensified reactors with real wastewater (both urine and membrane bioreactor effluent). We demonstrated electrochemical regeneration and adsorption in another cycle with real wastewater, which enhances feasibility for combined adsorption-regeneration processes that leverage electricity.
Future Activities:
Ammonia-selective adsorbents can manage reactive nitrogen in the environment and promote a circular nutrient economy. Weak acid cation exchangers loaded with zinc exhibit high ammonia selectivity but face two implementation barriers: the stability of the zinc-carboxylate bond in complex wastewaters and energy- and logistics-intensive adsorbent regeneration with acidic solutions. We examined the stability of the zinc-carboxylate bond in varying solutions (pure ammonium solution, synthetic urine, and real urine) and during electro-assisted regeneration. For electrochemical regeneration, both electrolyte concentration and current density influenced the tradeoff between ammonia regeneration and zinc elution. We found that the electrolyte concentration was the key factor influencing the regeneration efficiency of NH₃-selective adsorbents. Due to prevalent zinc elution, we designed an in-situ procedure for reforming the zinc-carboxylate bond and achieved similar adsorption densities between pre- and post-regenerated resin, thus enabling multiple cycle resin use. Ultimately, this research advances the understanding of ammonia-selective resins that can facilitate high-purity, selective, and durable nutrient recovery from waste streams.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 3 publications | 2 publications in selected types | All 2 journal articles |
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Clark B, Sharma N, Apraku E, Dong H, Tarpeh WA. Ligand Exchange Adsorbents for Selective Phosphate and Total Ammonia Nitrogen Recovery from Wastewaters. Accounts of Materials Research 2024;5(4):492-504. |
SV840417 (2023) |
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Apraku E, Laguna CM, Wood RM, Sharma N, Dong H, Tarpeh WA. Enhancing Resource Recovery through Electro-Assisted Regeneration of an Ammonia-Selective Cation Exchange Resin. ACS ES&T Water 2024. |
SV840417 (2023) |
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Supplemental Keywords:
Selective separation, nitrogen-selective adsorbent, electro-assisted regeneration, nutrient recoveryRelevant Websites:
Progress and Final Reports:
Original AbstractP3 Phase I:
Electro-Assisted Wastewater Nutrient Recovery | 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.