基质粒径与排空时间对潮汐流人工湿地运行效能的影响

Effect of substrate size and drained time on the treatment performance of tidal flow constructed wetlands

潮汐运行是强化人工湿地供氧的一种有效途径。为了解基质粒径对潮汐流人工湿地(TFCWs)处理效果及复氧过程的影响,研究了不同基质粒径TFCWs的处理性能,建立了TFCWs排空期氧转移过程的研究方法。结果表明基质粒径影响湿地对NH_(4)^(+)的吸附性及排空期基质孔隙氧体积占比进而影响处理效果,7~9 mm基质粒径的湿地达到最佳的氨氮去除率82.6%,3~5 mm基质粒径的湿地达到最佳的COD去除率88.2%,粒径基质小的湿地中氨氧化菌属和反硝化菌属的相对丰度更高,脱氮能力强;分析排空期基质孔隙氧体积占比变化与湿地微生物耗氧过程的联系,能够优化潮汐流湿地系统的排空时间,湿地微生物的耗氧活动主要集中在氧体积占比快速下降阶段,更长的排空时间对复氧能力没有明显提升,本研究中8 h的排空时间即可满足湿地系统的氧需求。

Tidal operation is an effective technique to enhance the oxygen supply of constructed wetlands.In order to explore the effect of substrate particle size on the treatment performance and reoxygenation process of tidal flow constructed wetlands(TFCWs),the treatment performance of TFCWs with different substrate particle sizes was studied,and the studying method of oxygen transfer process in TFCWs during drained period was established.The results showed that particle size of the substrate affected the adsorption of NH_(4)^(+)and oxygen concentration during the drained period,which in turn affected the treatment performance.The wetland with 7~9 mm substrate achieved the best ammonia removal rate of 82.6%,and wetland with 3~5 mm substrate achieved the best COD removal rate of 88.2%.The wetland with small substrate particle size had higher relative abundance of ammonia oxidizing bacteria and denitrifying bacteria,which had advantages in denitrification.Analyzing the relationship between the change in oxygen concentration and the oxygen consumption process during the drained period can optimize the drained time of TFCWs.The oxygen consumption activity of microorganisms was mainly concentrated at the rapid decline stage of oxygen concentration.The longer drained time did not significantly improve the reoxygenation ability.In this study,the drained time of 8 hours can meet the oxygen demand.