Everglades Research and Education Center, University of Florida, Belle Glade, FL, 33430, USA; Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, FL, 32611, USA; Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA.
Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA.
J Environ Manage. 2023 Nov 1;345:118735. doi: 10.1016/j.jenvman.2023.118735. Epub 2023 Aug 2.
Woodchip bioreactor (WBR) is commonly used to remove nitrate from drainage and runoff. However, the efficiency of nitrate removal in WBR is highly variable due to the properties of filling materials. In this study, we investigated the potential of recycling two waste materials, biochar (B) and silage leachate (SL), to enhance nitrate removal by providing a better living habitat and extra available carbon for denitrification. We constructed twelve lab-scale bioreactors with different filling materials (WBR, WBR + B, WBR + SL, WBR + B + SL), hydraulic retention times (HRT: 0.5-24 h), and nitrate concentrations (5.4-33 mg L) to test nitrate removal efficiency (NRE) and nitrate removal rate (NRR). Our results showed that the combination of biochar and silage leachate led to the highest NRE and NRR, with improvements of 23% and 48%, respectively, compared to WBR alone. However, the benefits of adding biochar and silage leachate were less apparent at longer HRTs. According to the results of our structural equation modeling (SEM), we have attributed the improved denitrification to several factors. These factors include the decrease in dissolved oxygen, saturated hydraulic conductivity, and pH value, as well as an increase in dissolved organic carbon after the addition of silage leachate. Therefore, our study provides evidence that recycling biochar and silage leachate as an additive to WBR could be a beneficial strategy for enhancing nitrate removal. Overall, this study highlights the potential of a win-win solution to improve the efficiency of nitrate removal in water treatment processes.
木屑生物反应器（WBR）常用于去除排水和径流中的硝酸盐。然而，由于填充材料的性质，WBR 中硝酸盐去除的效率变化很大。在这项研究中，我们研究了回收两种废物材料（生物炭（B）和青贮渗滤液（SL））的潜力，通过为反硝化提供更好的生存环境和额外的可用碳来增强硝酸盐去除。我们构建了 12 个具有不同填充材料（WBR、WBR+B、WBR+SL、WBR+B+SL）、水力停留时间（HRT：0.5-24 h）和硝酸盐浓度（5.4-33 mg L）的实验室规模生物反应器，以测试硝酸盐去除效率（NRE）和硝酸盐去除率（NRR）。我们的结果表明，生物炭和青贮渗滤液的组合导致 NRE 和 NRR 最高，与单独的 WBR 相比，分别提高了 23%和 48%。然而，在较长的 HRT 下，添加生物炭和青贮渗滤液的好处不太明显。根据我们的结构方程模型（SEM）的结果，我们将改善的反硝化归因于几个因素。这些因素包括添加青贮渗滤液后溶解氧、饱和水力传导率和 pH 值的降低，以及溶解有机碳的增加。因此，我们的研究提供了证据，表明将生物炭和青贮渗滤液回收作为 WBR 的添加剂可以是提高水处理过程中硝酸盐去除效率的一种有益策略。总的来说，这项研究强调了双赢解决方案的潜力，可以提高水处理过程中硝酸盐去除的效率。
