Le devenir du phosphore dans 2 Zones de Rejet Végétalisées: contributions de l'eau libre, du sol et des plantes

Papias, S.; Masson, M.; Morvannou, A.; Forquet, N.; Boutin, Catherine; Choubert, J.M.

Fate of phosphorus in two constructed wetlands receiving treated wastewater:contributions of free water, soil and plants retention | Le devenir du phosphore dans 2 Zones de Rejet Végétalisées: contributions de l'eau libre, du sol et des plantes

2018

Constructed Wetlands receiving treated wastewater (CWtw) have recently become attractive in France under the perception that they would increase water quality of the WWTP effluent. This study focuses on the fate of phosphorus (P) in 2 pilot-scale CWtw after 2 years of operation considering the 3 components: water, soil and plants. P mass balance was estimated by measures of water balance (inflow outflow and infiltration), flow composite samples, grab samples, water in soil, deposits, soil and plants samples. When considering inlet/outlet an efficiency of 83% and 39 % P removal was observed respectively in M1 and M2. Since the plant uptake was of 15-25 % of total P removal in both systems, the remaining fraction was either retained in the soil or infiltrated. Removal of P by harvesting of aboveground biomass is relevant in that case because of a lightly load system and confirms the need for a harvesting per year to avoid the release of up to 7 kg of P.

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