Controlling eutrophication of aquaculture production water using biochar: correlation of molecular composition with adsorption characteristics as revealed by FT-ICR mass spectrometry

Authors: RANCE, BARE - University Of Idaho; STRUHS, ETHAN - University Of Idaho; MIRKOUEI, AMIN - University Of Idaho; Overturf, Kenneth - Ken; CHACON-PATINO, MARTHA - Florida State University; MCKENNA, AMY - Florida State University; CHEN, HUAN - Florida State University; RAJA, KRISHNAN - University Of Idaho

Submitted to: Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2023
Publication Date: 9/30/2023
Citation: Rance, B., Struhs, E., Mirkouei, A., Overturf, K.E., Chacon-Patino, M., Mckenna, A., Chen, H., Raja, K.S. 2023. Controlling eutrophication of aquaculture production water using biochar: correlation of molecular composition with adsorption characteristics as revealed by FT-ICR mass spectrometry. Processes. 11(10), 2883. https://doi.org/10.3390/pr11102883.
DOI: https://doi.org/10.3390/pr11102883

Interpretive Summary: Aquaculture is the primary protein for over one-third of the world's population. The United States is a major importer of aquaculture products with an annual trade deficit for these products of over 21 billion dollars. The United States is making a large push to increase aquaculture production internally but this requires improved production practices to limit negative downstream effects such as eutrophication, in receiving waters. Eutrophication is the result of oversupplied nutrients, pollutants, and wastes from various operations (e.g., agriculture and aquaculture) to water bodies. Biochar has potential for the removal of waste products from water. Biochar is a charcoal-like material that is produced from plant materials that are decomposed at high temperatures. Results from this research demonstrated that biochar can significantly remove micronutrients such as nitrogen and ammonia from aquaculture production water. Aquaculture producers can utilize this information in the development of infrastructure to incorporate the use of biochar in production facilities and thereby actively reduce the release of harmful regulated micronutrients in a sustainable and economically feasible manner.

Technical Abstract: This study aims to construct a novel and sustainable approach for remediating aquaculturegenerated water contamination using various engineered biochars. Particularly, this study focuses on capturing nitrogen and phosphorus from downstream water of commercial fish farms in Magic Valley, Idaho, containing approximately 2.26 mg/L of nitrogen and 0.15 mg/L of phosphorous. The results indicate that the proposed approach can improve downstream waters by adsorbing micronutrients (e.g., nitrogen-ammonia, nitrate-n + nitrite-n, and total phosphorus). Water treatment time and biochar pH are two key parameters strongly associated with adsorbed compounds. Molecularlevel characterization of solvent-extracted organics from biochar materials (before and after water treatment) suggests increased levels of highly oxygenated molecules as a function of increasing water treatment time. Also, the results show the enrichment in organic species with higher molecular weight and increased double bond equivalents, with a compositional range similar to that of dissolved organic matter. Upon water treatment, extracted organics revealed higher abundances of compounds with higher H/C and O/C ratios. The engineered biochars, after water treatment, can be reused as nutrient-rich fertilizers. This study concluded that the engineered biochars could sequester more nitrogen and phosphorous over time. Also, the proposed approach can simultaneously increase fish production capacity and support the aquaculture industry in different regions by improving water quality and enabling aquaculture expansion.