School of Biological Sciences, University of Adelaide, Kaurna Country, Urrbrae, South Australia 5064, Australia; CSIRO Agriculture & Food, Kaurna Country, Gate 4 Waite Road, Urrbrae, South Australia 5064, Australia.
CSIRO Agriculture & Food, Kaurna Country, Gate 4 Waite Road, Urrbrae, South Australia 5064, Australia.
J Environ Manage. 2023 Jan 15;326(Pt A):116625. doi: 10.1016/j.jenvman.2022.116625. Epub 2022 Nov 7.
High organic loadings to constructed wetlands can result in water quality issues such as low dissolved oxygen and high ammonium concentrations, with artificial aeration a potential mitigation option. This study compared baseline (no aeration - NA), continuous aeration (CA), and intermittent aeration (IA) conditions to improve water quality in a tertiary treatment free water surface constructed wetland (FWS CW) with night time hypoxia/anoxia, and high nutrient concentrations. The response variables included dissolved oxygen (DO), total nitrogen (TN), ammonium nitrogen (NH-N), nitrate nitrogen (NO-N), total phosphorus (TP), phosphate (PO-P), and dissolved organic carbon (DOC). In situ aeration and monitoring was performed from April to June 2021 in a large, field-scale FWS CW, the Laratinga wetlands Mount Barker, South Australia. The results demonstrated that DO increased by an average 2.11 mg L from NA to CA during the night and 1.26 mg L and 1.84 mg L from NA to IA during the night and day respectively when averaging over the basins. The C/N ratio was very low and there was no significant influence of DO on DOC concentrations. There was no significant difference in TN concentrations with the application of aeration aside from a decrease in the channel at night from NA to IA, and an increase in NH-N resulted under IA compared with NA in Basin 1 and 2 during the day. This implies that the N loadings exceeded the wetland's ability to complete nutrient conversions at a rate that aligns with input rate. The concentrations of NO-N increased at night under CA and IA treatments suggesting that some nitrification was promoted, or there was inhibition of dissimilatory nitrate reduction to ammonium. The concentrations of TP and PO-P significantly increased with the aeration compared with no aeration, however there was no difference between the aeration treatments. This suggested that increased sediment resuspension during aeration increased P in the water. There was no change in DOC with the application of aeration. Overall, the DO increased with aeration application and may be able to better support the wetland ecology; however, the Laratinga wetland is overloaded and the capacity of the wetland to effectively transform and remove nutrients is inhibited, even with the application of artificial aeration.
高有机负荷会导致水质问题，如溶解氧低和铵浓度高，人工曝气是一种潜在的缓解措施。本研究比较了基线（无曝气-NA）、连续曝气（CA）和间歇曝气（IA）条件，以改善夜间缺氧/缺氧和高营养浓度的三级处理自由水面人工湿地（FWS CW）的水质。响应变量包括溶解氧（DO）、总氮（TN）、铵氮（NH-N）、硝酸盐氮（NO-N）、总磷（TP）、磷酸盐（PO-P）和溶解有机碳（DOC）。2021 年 4 月至 6 月，在南澳大利亚巴卡的拉拉丁加湿地进行了一项大型现场规模的 FWS CW 的原位曝气和监测。结果表明，与 NA 相比，夜间 CA 使 DO 平均增加 2.11mg/L，夜间和白天 NA 分别增加 1.26mg/L 和 1.84mg/L。C/N 比非常低，DO 对 DOC 浓度没有显著影响。除了夜间 NA 到 IA 时通道中的 DO 浓度下降外，曝气的应用对 TN 浓度没有显著影响，并且在白天，与 NA 相比，IA 使 1 号和 2 号盆地中的 NH-N 增加。这意味着氮负荷超过了湿地以与输入速率一致的速率完成养分转化的能力。夜间 CA 和 IA 处理下的 NO-N 浓度增加，表明促进了一些硝化作用，或者抑制了异化硝酸盐还原为铵。与无曝气相比，曝气使 TP 和 PO-P 浓度显著增加，但曝气处理之间没有差异。这表明曝气过程中增加的沉积物再悬浮增加了水中的 P。曝气应用对 DOC 没有影响。总体而言，DO 随着曝气的应用而增加，可能能够更好地支持湿地生态；然而，拉拉丁加湿地已经超载，即使应用了人工曝气，湿地有效转化和去除养分的能力也受到抑制。
