Sewage Treatment Performance of a Multistage Constructed Wetland Introducing a Hybrid Filtration Bed Combining Tidal Flow and Partial Saturation

Abstract

In this study, the sewage treatment performance of a multistage constructed wetland introducing a hybrid filtration bed combining tidal flow and partial saturation at the second and third treatment stages was elucidated. The enhancement of the aerobic treatment by the tidal flow was significant, resulting in the attainment of a removal efficiency of more than 97% for BOD and NH₄⁺-N irrespective of the filtration media material. On the other hand, the attainable removal efficiencies for T-N and T-P were 31 and 46%, respectively, when the mixture of zeolite and calcium silicate was used for the second filtration bed media. The results of this study confirmed that a higher sewage treatment performance can be attained for BOD, NH₄⁺-N and T-P removal by introducing the proposed hybrid filtration bed combining tidal flow and partial saturation in the multistage constructed wetland compared with a conventional hybrid system consisting of vertical and horizontal constructed wetlands, although the T-N removal efficiency still remains to be improved.