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It was evaluated the performance of French vertical flow constructed wetlands of different configurations, for the treatment of domestic residual water in the Tarn Department in France. Likewise, the functioning of these systems, at the mesocomos level, for the removal of emerging contaminants in the tertiary treatment of the effluent of a municipal plant in Izúcar de Matamoros, Mexico was evaluated, comparing two species of macrophytes, Phragmites australis and Typha latifolia. The results obtained in the Tarn show that these systems achieve high removal rates of organic matter and nitrogen, with a stable operation over time. In Izúcar de Matamoros, when comparing the two macrophytes, were observed slightly better results of organic load and some organic micropollutants removal for Typha latifolia, with turbidity values that approach the value established for urban public use water accordingly to Mexican regulations. [ABSTRACT FROM AUTHOR]

In France, gravel vertical flow constructed wetlands (gVFCWs) were adapted to treat raw wastewater, which led to important accumulations of matter in filters (organic and mineral). To prevent clogging, large gravel sizes were employed (Ø 2-6 mm). The aim of this paper was to present the influences of matter accumulation on the hydraulic and biological behaviour of the system. A one-year survey of accumulated matter content and potential respiration activities was completed in three gVFCWs (operating for 3, 4 and 8 years). Cores were sampled into filters. Results showed a vertical stratification of accumulated matter and respiration rates. Dry accumulated matter quantities ranged from 20 kg m-2 (3 and 4 years operating) to 80 kg m-2 in the oldest plant (8 years). Potential respiration was larger in the oldest plant (75 g O2m-2 h-1) than in the most recent one (15 g O2m-2 h-1). Accumulated matter seemed to play a role both on the water retention (enhancing initial percolation time by 5 times) and biological profile (enhancing microfauna's diversity). Contrary to what is generally proposed in the literature, accumulated matter in French gVFCWs seemed to provide better treatment efficiency without leading to surface clogging compared to systems using sand. [ABSTRACT FROM AUTHOR]