Constructed Wetland as a Low-Energy Technique for Wastewater Treatment -- Seasonal Impact, Performance and Phytomanagement.

This work aims to study the seasonal impact on pollutant removal efficiency of constructed wetland (CW) units which treat domestic wastewater in the region of Rabat, Morocco. In this context, four vertical flow-constructed wetlands (VFCWs) were investigated for one year. Each CW unit has a surface area of 1m² and a depth of 60 cm. The difference between the units is the vegetation. The experiments are conducted on a laboratory scale and outdoors, to investigate also the direct effect of the climate. The purpose is to investigate the CWs performances with two different plant species (Phragmites Australis and Arundo Donax) and plant arrangements (mono-culture and poly-cultures). Since the region of Rabat has a semi-arid climate, plants behave during seasonal changes was explored. The elimination of organic matters showed a seasonal variation in the CW systems, with higher rates during the hot season and lower rates during the cold ones. Planted systems outperformed the unplanted system and the polyculture system was the most effective, reaching removal rates of 99.47%, 99.58%, and 85.64%, for, COD, BOD₅, and TSS in the summer season where the temperature reaches its maximum promoting plant growth as well as microbial activity. Anyhow, results showed that the VFCWs used in this study are a successful technology for the region that is cost-effective and requires low energy. [ABSTRACT FROM AUTHOR]