Abstract
There is a need to develop practical methods to reduce nitrate-nitrogen loads from recirculating aquaculture systems to facilitate increased food protein production simultaneously with attainment of water quality goals. The most common wastewater denitrification treatment systems utilize methanol-fueled heterotrophs, but sulfur-based autotrophic denitrification may allow a shift away from potentially expensive carbon sources. The objective of this work was to assess the nitrate-reduction potential of fluidized sulfur-based biofilters for treatment of aquaculture wastewater. Three fluidized biofilters (height 3.9m, diameter 0.31m; operational volume 0.206m3) were filled with sulfur particles (0.30mm effective particle size; static bed depth approximately 0.9m) and operated in triplicate mode (Phase I: 37-39% expansion; 3.2-3.3min hydraulic retention time; 860-888L/(m2min) hydraulic loading rate) and independently to achieve a range of hydraulic retention times (Phase II: 42-13% expansion; 3.2-4.8min hydraulic retention time). During Phase I, despite only removing 1.57±0.15 and 1.82±0.32mg NO3-N/L each pass through the biofilter, removal rates were the highest reported for sulfur-based denitrification systems (0.71±0.07 and 0.80±0.15gN removed/(L bioreactor-d)). Lower than expected sulfate production and alkalinity consumption indicated some of the nitrate removal was due to heterotrophic denitrification, and thus denitrification was mixotrophic. Microbial analysis indicated the presence of Thiobacillus denitrificans, a widely known autotrophic denitrifier, in addition to several heterotrophic denitrifiers. Phase II showed that longer retention times tended to result in more nitrate removal and sulfate production, but increasing the retention time through flow rate manipulation may create fluidization challenges for these sulfur particles.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 10-18 |
| Number of pages | 9 |
| Journal | Aquacultural Engineering |
| Volume | 68 |
| DOIs | |
| State | Published - Sep 1 2015 |
| Externally published | Yes |
Bibliographical note
Funding Information:The authors wish to thank the Herrick Foundation (Detroit, Michigan, USA) for their gracious support. This research was additionally supported by the USDA Agricultural Research Service under Agreement no. 59-1930-0-046 . A debt of gratitude is due to Shanen Cogan and Fred Ford for technical assistance and Issra Arif for initial assistance with the testing. Dr. Laura Christianson has been a Research Agricultural Engineer for The Conservation Fund's Freshwater Institute, Shepherdstown, WV since 2013. She finished her Ph.D. in Agricultural Engineering (Co-Major: Sustainable Agriculture) at Iowa State University in December 2011 where her dissertation focused on improvement of agricultural drainage water quality through the use of denitrification “woodchip” bioreactors. During her Ph.D., she spent a year in New Zealand studying agricultural water quality and denitrification technologies as a Fulbright Fellow. Laura previously completed a M.S. in Biological and Agricultural Engineering at Kansas State University and a B.S. in Biosystems Engineering at Oklahoma State University. Christine Lepine is a Research Technician for The Conservation Fund's Freshwater Institute (TCFFI), Shepherdstown, WV. She has been with TCFFI since 2014, originally starting as a Research Intern. She also recently graduated magna cum laude from Shepherd University with a B.S. in Environmental Studies, Concentration of Resource Management. Scott Tsukuda is the Director of Operations at The Conservation Fund's Freshwater Institute (TCFFI), Shepherdstown, WV, with his focus on energy monitoring and auditing. Some of his past work has included MS Excel computer modeling, PLC programming, denitrification technologies and alternative waste treatment systems demonstration. He is a member of the Instrumentation, Systems and Automation Society (ISA) and the Institute of Electrical and Electronics Engineers (IEEE) plus holds a M.S. in Agricultural Engineering and a B.S. in Agricultural Engineering from Cornell University. Past certifications include Microsoft Certified Systems Engineer (MCSE). He is currently Certified Energy Manager (CEM). Dr. Keiko Saito has been a Research Assistant Professor at University of Maryland Baltimore County's Institute of Marine and Environmental Technology since 2010. Her research focuses on aquatic microbial ecology and aquacultural microbiology, and on applying molecular approaches to link the critical roles of microbial community composition, functional diversity, ecosystem processes, and bio-degradation/remediation. She is working toward development and improvement of microbially mediated waste treatment technologies for next-generation aquaculture practices. Dr. Steven T. Summerfelt , Professional Engineer, is Director of Aquaculture Systems Research at The Conservation Fund's Freshwater Institute (TCFFI), Shepherdstown, WV, where he has been an employee since 1992. He is Project Leader on TCFFI's USDA-ARS project titled, “Development of Sustainable Land-based Aquaculture Production Systems” and has authored or co-authored of over 60 refereed papers, 9 book chapters, and a book titled “Recirculating Aquaculture Systems”. Steve has designed several large private and public fish culture facilities using closed-containment technologies. He has B.S., M.S., and Ph.D. degrees in the fields of chemical and environmental engineering.
Publisher Copyright:
© 2015 The Authors.
Keywords
- Autotrophic
- Denitrification
- Fluidized biofilter
- Mixotrophic
- Recirculating aquaculture
- Sulfur
