Onsite one stage constructed wetland fed by raw wastewater: performances and resilience of the system

Overview & Synopsis

Onsite sanitation systems in Europe are evaluated through a CE Marked procedure done on a platform test under a specific schedule of loads (EN 12566). Nevertheless this test procedure conditions does not represent the real conditions of treatment systems in term of wastewater characteristics and loads. On another angle, in France, systems implemented for capacities above 20 p.e. do not need CE marked procedure but have to comply with performances requirements. For constructed wetlands, it leads to a situation where design for 21 p.e. can be more compact than for 15 p.e.. Some companies have fulfil CE marked procedure for one stage vertical flow constructed design between 1.2 and 2 m² per capita to implement more compact system. This study aims at evaluating, under real conditions the behaviour of a one stage unsaturated/saturated vertical flow constructed wetlands (as designed for small communities, Pringent et al., 2013; Silveira et al., 2015) and fed by raw wastewater (no septic tank). The objectives were to evaluate performances, robustness and resilience of the system when facing load variations and determine possible limits of the system.