The Institute of Municipal Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang, 312058, People's Republic of China.
Department of Civil and Environmental Engineering, University of Wisconsin, Milwaukee, WI, 53211, USA.
Environ Sci Pollut Res Int. 2018 Aug;25(24):24073-24083. doi: 10.1007/s11356-018-2418-z. Epub 2018 Jun 9.
Clogging is a major operational and maintenance issue associated with the use of constructed wetlands. In this study, four lab-scale vertical flow constructed wetlands (VFCW) were used to fully understand the development mechanisms of various types of clogging and their recovery characteristics. The VFCWs were fed with glucose solution, starch suspension with and without bacteriostat, glucose, and starch mixed solution, respectively, to simulate Bio-clogging, organic particle clogging (Op-clogging), inert particle clogging (Ip-clogging), and the combination of Bio-clogging and Op-clogging (C-clogging). Resting operations with water decline were applied to relieve the clogging in the VFCWs. The results indicate that Op-clogging occurred first, followed by C-clogging and Bio-clogging. Ip-clogging took the longest time to develop and did not occur by the end of this study. The microscope analysis found that the extracellular polymeric substances (EPS) bonded the starch particles together to form a dense membrane-like structure and promoted the clogging process. In addition, surface clogging was observed in all four experimental beds. Op-clogging occurred much closer to the surface than those caused by soluble organic matter and inert particles. Furthermore, the growth of biofilm caused significant decline in hydraulic conductivity, whereas its influence on porosity was relatively slight. Moreover, applying resting operation with water decline was effective for recovery from Bio-clogging, Op-clogging, and C-clogging in VFCWs except for Ip-clogging. The results also implied the recovery rates through applying resting operation with water decline were much higher than that with constant water level.
堵塞是与人工湿地使用相关的一个主要运营和维护问题。在这项研究中，使用了四个实验室规模的垂直流人工湿地（VFCW）来充分了解各种类型堵塞的发展机制及其恢复特性。VFCWs 分别用葡萄糖溶液、含和不含抑菌剂的淀粉悬浮液、葡萄糖和淀粉混合溶液进料，以模拟生物堵塞、有机颗粒堵塞（Op-clogging）、惰性颗粒堵塞（Ip-clogging）以及生物堵塞和有机颗粒堵塞的组合（C-clogging）。采用水位下降的休眠操作来缓解 VFCWs 中的堵塞。结果表明，Op-clogging 首先发生，其次是 C-clogging 和 Bio-clogging。Ip-clogging 发展所需时间最长，到本研究结束时仍未发生。显微镜分析发现，细胞外聚合物（EPS）将淀粉颗粒结合在一起形成致密的膜状结构，促进了堵塞过程。此外，在所有四个实验床中都观察到表面堵塞。Op-clogging 比可溶性有机物和惰性颗粒引起的堵塞更靠近表面。此外，生物膜的生长导致水力传导率显著下降，而对孔隙率的影响相对较小。此外，对于 VFCWs 中的生物堵塞、有机颗粒堵塞和 C-clogging，采用水位下降的休眠操作进行恢复是有效的，除了 Ip-clogging 之外。结果还表明，通过采用水位下降的休眠操作进行恢复的恢复率远高于采用恒定水位的恢复率。
