Grantee Research Project Results

Electro-Assisted Wastewater Nutrient Recovery

EPA Grant Number: SU840151
Title: Electro-Assisted Wastewater Nutrient Recovery
Investigators: Tarpeh, William A , Dong, Hang
Current Investigators: Tarpeh, William A , Dong, Hang , Kogler, Anna , Clark, Brandon , Chow, William
Institution: Stanford University
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2020 through November 30, 2021
Project Amount: $25,000
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources

Description:

The objectives of this proposed work are (1) to design and experimentally demonstrate deployable, durable and nutrient-selective nano-adsorbents to enable selective nutrient capture; (2) to develop novel on-site electrochemical regeneration and recovery process for the nano-adsorbents to enable pure fertilizer production with minimal chemical inputs and transportation; and (3) to validate the field performance of electro-assisted nutrient recovery at various scales at the Codiga Resource Recovery Center. Embedded nanoparticles enable selective adsorption of N and P and efficient desorption via bulk pH shift, which can be achieved through on-site electrochemical water-splitting. Our proposal synergistically combines molecular-level design, lab-scale development, and field demonstration to advance nutrient management benefits for people, prosperity and planet.  Selective nutrient capture benefits people by preventing harmful algal blooms in drinking water sources and recreational areas to improve the quality of people’s lives; simultaneous recovery benefits prosperity by recovering nutrients as essential agricultural fertilizers to maximize economic benefits; and combination of capture and recovery benefits the planet by re-managing nutrient cycles from linear extract-and-emit schemes to closed recycle loop to reduce emissions from energy-intensive nitrogen-fixation (N) and conserve natural resources by reducing phosphorus-mining (P). Educationally, we partner with the Codiga Center, to engage diverse tour groups (e.g., local community, K-12 students, campus staff and students) to increase awareness of resource-efficient water treatment. Students in Introduction to Chemical Engineering and Chemical Engineering Plant Design will also participate in hands-on laboratory and scale-up studies to evaluate adsorption capacity, regeneration efficiency, and selectivity.

Objective:

The overarching goal of the proposed work is to develop and demonstrate a self-sustaining selective nutrient capture and recovery unit. This project addresses a critical barrier to sustainable water treatment: a lack of cost-effective, flexible-scale options for preventing nutrient-induced algal blooms. This barrier stems from a lack of scalable unit processes capable of both removal and recovery of nitrogen and phosphorus. Recovered products must be high-purity, which demands selective capture of nitrogen and phosphorus as fertilizers and other commodity chemicals. We address this technical challenge using selective nano-adsorbents because they are tunable to different pollutants and amenable to regeneration to extract value-added products. We also advance electrochemical regeneration, which can be applied for on-site treatment in remote, rural, and disadvantaged communities because it replaces chemical inputs with electricity.

Expected Results:

Our primary outputs are novel selective nano-adsorbents and an enhanced molecular understanding of their material and performance properties, novel electrochemical regeneration methods that minimize chemical input, and several functional systems varying from lab to pilot scale. Our first objective will reduce nutrient discharges to prevent harmful algal blooms in drinking water sources and recreational areas. Our second objective (electrochemical regeneration) will minimize chemical, cost, and energy inputs for water treatment that enable on-site, deployable nutrient management and fertilizer production. Our third objective will provide interactive prototypes to engage diverse audiences, and proof-of-concept for future industrial partnerships. We will quantitatively evaluate performance metrics at the molecular (e.g., adsorption capacity, selectivity), process (e.g., regeneration efficiency), and systems scales (e.g., environmental impacts) to advance electro-assisted nutrient recovery.

Because 80% of wastewater is discharged without treatment, nutrient discharge induces algal blooms that damage aquatic ecosystems and threaten human health (algal cyanotoxins, methemoglobinemia in infants). In the U.S, this eutrophication affects 70% of freshwater and costs $2.1 billion annually to remediate. In response to the urgent need to feed a growing population while preserving the environment, the National Academy of Engineering identified managing the nitrogen cycle as the only element-specific 21st century grand challenge. Reimagining aqueous nutrients as products rather than pollutants can reduce nutrient discharges and even remediate legacy emissions. We imagine a truly zero-discharge future in which every wastewater is mined for maximal value (e.g., fertilizers, disinfectants, commodity chemicals). To achieve this vision, we evaluate molecularly-designed adsorptive materials that selectively remediate nitrogen, and combine them with existing phosphate-selective adsorbents into a novel recovery process.

Publications and Presentations:

Publications have been submitted on this project: View all 3 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 2 journal articles for this project

Supplemental Keywords:

life-cycle analysis, nanotechnology, green chemistry, sustainable water management, water purification technologies, agricultural wastewater treatment

Progress and Final Reports:

Final Report

P3 Phase II:

Electro-Assisted Wastewater Nutrient Recovery  | 2023 Progress Report