Search Results (2)

Leachate and storm-driven runoff from silage storage bunkers can degrade receiving water bodies if left untreated. This study evaluated a novel treatment system consisting of three treatment tanks with a moving-bed biofilm reactor and paired side-by-side denitrifying woodchip bioreactors for the ability to reduce influent nutrient mass loads. Flow-based samples were taken at four locations throughout the system, at the inflow to the first tank, outflow from the tanks prior to entering the woodchip bioreactors, and from the outflows of both bioreactors. Samples were analyzed for concentrations of nitrogen (N) and phosphorus (P) species. Inflow concentrations were reduced from the bioreactor outflows by an average of 35% for total N (TN) and 16% for total P (TP) concentrations on a storm event basis. The treatment system cumulatively removed 76% of the TN mass load, 71% of the nitrite + nitrate-N (NO₂⁻+NO₃⁻-N) load, 26% of the TP mass load, and 19% of the soluble reactive P load, but was a source of ammonium-N, based on the monitoring of 16 storm events throughout 2019. While the system was effective, very low NO₂⁻+NO₃⁻-N concentrations in the silage bunker runoff entered the bioreactors, which may have inhibited denitrification performance. Full article

Biochar soil amendment to agricultural systems can reduce nitrogen (N) leaching; however, application to agricultural nitrogen treatment systems has not been extensively explored. The objective of this study was to assess the impact on N leaching in soils receiving repeated N applications which may be observed in agricultural treatment systems. In this study, 400 °C, 700 °C, and oxidized 700 °C corncob biochar was amended to sandy loam soil columns at 5% (wt/wt) to assess the impacts to N cycling following repeated synthetic N applications. Columns received weekly applications of either organic N (ORG-N), ammonium (NH₄⁺-N), or nitrate (NO₃⁻-N) and the N effluent, gaseous emissions, and soil N retention was measured. Biochar produced at 400 °C significantly reduced N leaching compared to control columns by 19% and 15% for ORG-N and NH₄⁺-N, respectively, with application concentrations similar to silage bunker runoff. For NO₃⁻-N applications, 700 °C biochar significantly reduced leaching by 25% compared to the controls. The primary mechanism reducing N effluent for biochar amended columns was enhanced soil retention of ORG-N and NO₃⁻-N. Biochar surface chemistry analysis measured an increase in oxygenated functional groups and cationic minerals on the biochar surface, which likely enhanced retention through cationic bridging or the development of an organomineral layer on the biochar surface. Results indicated biochar amendment to agricultural treatment systems receiving N runoff may reduce the risk of N leaching. Full article