Journal Article

French vertical flow constructed wetlands: A need of a better understanding of the role of the deposit layer

Milieux aquatiques, écologie et pollutions (UR MALY) ; Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Molle, Pascal

2014

Overview

French vertical flow constructed wetlands, treating directly raw wastewater, have become the main systems implemented for communities under 2,000 population equivalent in France. Like in sludge drying reed beds, an organic deposit layer is formed over time at the top surface of the filter. This deposit layer is a key factor in the performance of the system as it impacts hydraulic, gas transfers, filtration efficiency and water retention time. The paper discusses the role of this deposit layer on the hydraulic and biological behaviour of the system. It presents results from different studies to highlight the positive role of the layer but, as well, the difficulties in modelling this organic layer. As hydraulic, oxygen transfers, and biological activity are interlinked and impacted by the deposit layer, it seems essential to focus on its role (and its quantification) to find new developments of vertical flow constructed wetlands fed with raw wastewater.

• Publisher: CCSD,IWA Publishing,International Water Association
• Subject: Applied sciences / Artificial wetlands / Biological activity / Biological effects / Environmental Sciences / Exact sciences and technology / Hydraulics / Modelling / Oxygen transfer / Pollution / Raw wastewater / Reed beds / Reedbeds / Retention time / Sewage / Sludge / Sludge drying / Vertical flow / Vertical mixing / Waste Disposal, Fluid - methods / Wastewater / Wastewater treatment / Water purification / Water treatment and pollution / Wetlands