Abstract
Cold temperatures limit nitrate-N load reductions of woodchip bioreactors in higher-latitude climates. This two-year, on-farm (Willmar, Minnesota, USA) study was conducted to determine whether field-scale nitrate-N removal of woodchip bioreactors can be improved by the addition of cold-adapted, locally isolated bacterial denitrifying strains (bioaugmentation) or dosing with a carbon (C) source (biostimulation). In Spring 2017, biostimulation removed 66% of the nitrate-N load, compared to 21% and 18% for bioaugmentation and control, respectively. The biostimulation nitrate-N removal rate (NRR) was also significantly greater, 15.0 g N m−3 d−1, versus 5.8 and 4.4 g N m−3 d−1, for bioaugmentation and control, respectively. After five weeks of operation, bioclogging of the biostimulation beds limited dosing for the remainder of the experiment; NRR was greater for biostimulation in Fall 2017, but in Spring 2018 there were no differences among treatments. Carbon dosing did not increase outflow of dissolved organic C concentration. The abundance of one of the inoculated strains, Cellulomonas cellacea strain WB94, increased over time, while another, Microvirgula aerodenitrificans strain BE2.4, increased briefly, returning to background levels after 42 d. Eleven days after inoculation in Spring 2017, outflow nitrate-N concentrations of bioaugmentation were sporadically reduced compared to the control for two weeks, but the effects were insignificant over the study period. The study suggests that biostimulation and bioaugmentation are promising technologies to enhance nitrate removal during cold conditions. A means of controlling bioclogging is needed for biostimulation, and improved means of inoculation and maintaining abundance of introduced strains is needed for bioaugmentation. In conclusion, biostimulation showed greater potential than bioaugmentation for increasing nitrate removal in a woodchip bioreactor, whereas both methods need improvement before implementation at the field scale.
| Original language | English (US) |
|---|---|
| Article number | 106920 |
| Journal | Ecological Engineering |
| Volume | 191 |
| DOIs | |
| State | Published - Jun 2023 |
Bibliographical note
Funding Information:Outside funding was received from: Minnesota's Discovery, Research, and InnoVation Economy ( MnDRIVE) Environment Initiative, Minnesota Department of Agriculture (Project No. 108837 ); Minnesota Agricultural Water Resource Center/Discovery Farms Minnesota . E.L.A. was partly supported by the USDA North Central Region Sustainable Agriculture Research and Education Graduate Student Grant Program. Mention of companies and manufacturers' names does not imply endorsement by the USDA. The USDA is an equal opportunity provider and employer.
Funding Information:
We acknowledge and thank Ed Dorsey, Scott Schumacher, Todd Schumacher; Drs. Laura Christianson, Andry Ranaivoson, and Chanlan Chun; and a host of staff and students too numerous to mention. We thank the two peer reviewers and associate editor for their thoughtful comments that substantially improved the manuscript. Outside funding was received from: Minnesota's Discovery, Research, and InnoVation Economy (MnDRIVE) Environment Initiative, Minnesota Department of Agriculture (Project No. 108837); Minnesota Agricultural Water Resource Center/Discovery Farms Minnesota. E.L.A. was partly supported by the USDA North Central Region Sustainable Agriculture Research and Education Graduate Student Grant Program. Mention of companies and manufacturers' names does not imply endorsement by the USDA. The USDA is an equal opportunity provider and employer.
Publisher Copyright:
© 2023
Keywords
- Agricultural drainage
- Bioaugmentatioin
- Biostimulation
- Carbon dosing
- Denitrifying bioreactor