Electrical stimulation for enhanced denitrification in woodchip bioreactors: Opportunities and challenges

Thumbnail Image
Date
2018-01-01
Authors
Law, J.
Moorman, T.
Ong, Say
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Person
Soupir, Michelle
Associate Dean
Person
Raman, D. Raj
Morrill Professor
Research Projects
Organizational Units
Organizational Unit
Organizational Unit
Organizational Unit
Iowa Nutrient Research Center
The Iowa Nutrient Research Center was established to pursue science-based approaches to evaluating the performance of current and emerging nutrient management practices and providing recommendations on practice implementation and development. Publications in this digital repository are products of INRC-funded research. The INRC is headquartered at Iowa State University and operates in collaboration with the University of Iowa and the University of Northern Iowa. Additional project information is available at: https://www.cals.iastate.edu/inrc/
Journal Issue
Is Version Of
Versions
Series
Department
Civil, Construction and Environmental EngineeringAgricultural and Biosystems EngineeringIowa Nutrient Research Center
Abstract

Woodchip bioreactors are being implemented for the removal of nitrates in groundwater and tile water drainage. However, low nitrate removals in denitrifying woodchip bioreactors have been observed for short hydraulic retention time (HRT) and low water temperature (°C). One potential approach to improve woodchip bioreactor performance is to provide an alternative and readily available electron source to the denitrifying microorganisms through electrical stimulation. Previous work has demonstrated the capability of bio-electrochemical reactors (BER) to remove a variety of water contaminants, including nitrate, in the presence of a soluble carbon source. The objective of this study was to evaluate the denitrification efficiency of electrically augmented woodchip bioreactors and conduct a simple techno-economic analysis (TEA) to understand the possibilities and limitations for full-scale BER implementation for treatment of agricultural drainage. Up-flow column woodchip bioreactors were studied included two controls (non-energized, and without electrodes), two electrically enhanced bioreactors, each using a single 316 stainless steel anode coupled with graphite cathodes, and two electrically enhanced bioreactors, each with graphite for both anode and cathodes. Both pairs of electrically enhanced bioreactors demonstrated higher denitrification efficiencies than controls when 500 mA of current was applied. While this technology appeared promising, the techno-economic analysis showed that the normalized N removal cost ($/kg N) for BERs was 2–10 times higher than the base cost with no electrical stimulation. With our current reactor design, opportunities to make this technology cost effective require denitrification efficiency of 85% at 100 mA. This work informs the process and design of electrically stimulated woodchip bioreactors with optimized performance to achieve lower capital and maintenance costs, and thus lower N removal cost.

Comments

This article is published as Law, J. Y., M. L. Soupir, D. R. Raman, T. B. Moorman, and S. K. Ong. "Electrical stimulation for enhanced denitrification in woodchip bioreactors: Opportunities and challenges." Ecological Engineering 110 (2018): 38-47. doi: 10.1016/j.ecoleng.2017.10.002. Posted with permission.

Description
Keywords
Citation
DOI
Copyright
Collections