Grantee Research Project Results

Final Report: Ammonia Removal During Solid Waste Anaerobic Digestion Increasing Energy Generation and Reactive Nitrogen Recovery

EPA Grant Number: SV839352
Title: Ammonia Removal During Solid Waste Anaerobic Digestion Increasing Energy Generation and Reactive Nitrogen Recovery
Investigators: Grimberg, Stefan J. , Holsen, Tom M , Powers, Susan E. , Ajayi, Olutooni , Fleming, Abigail , Guo, Jennifer , Hunt, Jacob , Knapp, Michael , Meyerson, Gabrielle , Roberts, Alexander , Atkinson, Brooke , Rhodes, Steven , Neu, Patrick , Protas, Michael , Quispe Cardenas, Luz Estefanny , Randall, Andrew A. , Dwyer, Bryan , Hartle, Cody , Melgar, Daniel , Jaworski, Ellen , Sweeter, Gavin , Glasgow, Heath , Davis, Justin , Fudo, Lucas , Bredehoeft, Madison , Kitts, Mathew , Goetze, Rhiannon , Pawlowski, Sarah , Gallimore-Repole, Sasha
Institution: Clarkson University
EPA Project Officer: Page, Angela
Phase: II
Project Period: March 1, 2018 through February 29, 2020 (Extended to February 28, 2021)
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2017) Recipients Lists
Research Category: P3 Awards , Sustainable and Healthy Communities , P3 Challenge Area - Safe and Sustainable Water Resources

Objective:

Clarkson has a 2-stage pilot-scale anaerobic digester with a processing capacity of 600 pounds of food waste per day. It’s pre-COVID foodwaste loading was up to 400 pounds of food water per day. Anaerobic digestion occurs in the absence of oxygen generating biogas during this process as microorganisms break down the food waste. Biogas is a renewable energy source composed of carbon dioxide and methane. Another byproduct of this process is called digestate. Digestate is a wet mixture rich in nutrients. Nitrogen present in the FW is converted to ammonia during AD.  Ammonia at high concentrations, however, has been shown to inhibit methanogens i.e. biogas production. Ammonia, however, represents a valuable fertilizer.  To address this issue, the overall objective of this research was to design, construct, and evaluate a pilot-scale ammonia removal and recovery process for a FW anaerobic digester.

Summary/Accomplishments (Outputs/Outcomes):

This process increased the environmental and economic value of the AD system through greater biogas yields and more valuable fertilizer production. Ammonia was continuously removed from the digestate and transferred into a potassium-based draw solution using cation exchange membranes. This ammonia was then stripped from the draw solution and recovered within sulfuric acid traps to create ammonium sulfate, which can be used as a valuable fertilizer additive. The FW digester contains two parallel second-stage tanks, one of which was connected to this removal and recovery process, while the other served as a control reactor allowing for side-by-side monitoring of the two processes. Research focused on the design and construction of this system, followed by data collection to quantify the performance of this pilot-scale operation. In the membrane assisted AD process ammonia nitrogen concentration decreased by 42%, which corresponded with a 55% increase in biogas production. The system recovered 99% of this removed nitrogen.  Economic analysis of the membrane assisted process determined a payback period of less than 3 years for the process.

Conclusions:

The project demonstrated that ammonia inhibition of foodwaste anaerobic digestion can be mitigated effectively through the recovery of ammonia as a fertilizer while increasing energy production.  This process could be model of distributed foodwaste management.

Journal Articles:

No journal articles submitted with this report: View all 11 publications for this project

Supplemental Keywords:

Anaerobic Digestion, Ammonia Recovery, Food Waste

Progress and Final Reports:

Original Abstract

2018 Progress Report

2019 Progress Report

P3 Phase I:

NH4 Removal and Reactive Nitrogen Recovery  | Final Report