Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, 410125, PR China.
Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan, 410125, PR China.
Chemosphere. 2019 Jul;226:273-281. doi: 10.1016/j.chemosphere.2019.03.084. Epub 2019 Mar 16.
Rice straw was applied often as a carbon source to improve nitrogen removal; however, few studies have considered the effect of rice straw on nitrous oxide (NO) emission during nitrogen removal in constructed wetlands (CWs). We constructed eighteen combined systems, consisting of rice straw ponds and surface flow CWs to investigate the effect of rice straw application on NO emission in three strengths of swine wastewater treatments. The results showed rice straw (RS) treatment increased 131.5% of NO emission factor from low strength CWs, but decreased 37.2-43.7% of NO emission factors for medium and high strengths compared with no rice straw (NRS) treatment. The RS application led to an average 10.7% increase in the potential denitrification rate, and simultaneously enhanced gene abundances of the total bacteria (16S rRNA), ammonia-oxidising archaea, ammonia-oxidising bacteria, nitrate reductase, and NO reductase (nosZ) for all strengths CWs. The multiple regression model revealed NO emissions were strongly related to water temperature, nitrate, chemical oxygen demand, and denitrification genes. The proportion of nosZ gene abundance in 16S rRNA was higher in RS (0.7-1.3%) than NRS (0.4-0.9%) for medium and high strengths, while an opposite trend was observed for low strength. The discrepancy was responsible for increasing or decreasing NO emission by RS application among different strengths. These findings indicated the effectiveness of RS application to control NO emissions from the surface flow CWs was related to the pollution level of wastewater.
稻草常被用作碳源以提高氮去除率；然而，很少有研究考虑稻草对人工湿地（CWs）中氮去除过程中一氧化二氮（NO）排放的影响。我们构建了 18 个组合系统，包括稻草池塘和表面流 CWs，以研究稻草应用对三种强度猪废水处理中 NO 排放的影响。结果表明，与无稻草（NRS）处理相比，稻草（RS）处理使低强度 CWs 的 NO 排放因子增加了 131.5%，但使中强度和高强度 CWs 的 NO 排放因子降低了 37.2-43.7%。RS 应用导致潜在反硝化速率平均增加了 10.7%，同时增强了所有强度 CWs 的总细菌（16S rRNA）、氨氧化古菌、氨氧化细菌、硝酸盐还原酶和一氧化二氮还原酶（nosZ）的基因丰度。多元回归模型表明，NO 排放与水温、硝酸盐、化学需氧量和反硝化基因密切相关。在中高强度下，RS（0.7-1.3%）中 nosZ 基因丰度在 16S rRNA 中的比例高于 NRS（0.4-0.9%），而在低强度下则相反。这种差异是 RS 应用在不同强度下增加或减少 NO 排放的原因。这些发现表明，RS 应用控制表面流 CWs 中 NO 排放的有效性与废水的污染水平有关。
