Introduction:

Constructed wetlands (CWs) have been widely used in domestic wastewater treatment, and plants are the main component in pollutant removal.

Objective:

To evaluate the efficiency of Sagittaria latifolia and Sagittaria lancifolia in the removal of basic pollutants in nine free flow constructed wetlands (FFCWs).

Methodology:

Nine FFCWs were established, three without vegetation (FFCW-Control), three with Sagittaria lancifolia (FFCW-S-Lan) and three with Sagittaria latifolia (FFCW-S-Lat); for each of them, temperature, pH, total suspended solids (TSS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), fecal coliforms (FCs), and bacterial and plant biomass were determined.

Results:

Sagittaria latifolia presented 21.4 ± 1.90 mg·L-1 of TSS, 14.6 ± 4.44 mg·L-1 of BOD5, 29.55 ± 10.80 mg·L-1 of COD and 1 000 MPN·100 mL-1 of FCs, while Sagittaria lancifolia had 12.6 ± 3.80 mg·L-1 of TSS, 24.4 ± 2.09 mg·L-1 of BOD5, 59.62 ± 5.87 mg·L-1 of COD and 100 MPN·100 mL-1 of FCs. The removal efficiency of Sagittaria latifolia in TSS, BOD5, COD and FCs was 94, 97, 96 and 99 %, respectively, while for Sagittaria lancifolia it was 97, 94, 93 and 99.9 %, respectively.

Study limitations:

The behavior of Sagittaria latifolia and Sagittaria lancifolia within the CWs is documented for only one year, whereas it is known that most of the macrophytes used reach their maximum pollutant removal efficiency between two and three years.

Originality:

There are few reports on the ability of Sagittaria latifolia and Sagittaria lancifolia to remove basic pollutants when used in a CW as a primary or secondary treatment.

Conclusions:

The treated water meets the discharge criteria of NOM-001-SEMARNAT-1996 and NOM-003-SEMARNAT-1997, and can be reused for other purposes.