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Removal efficiency of domestic wastewater contaminants in horizontal subsurface
flow constructed wetlands planted with
Cyperus liguralis
(Cyperaceae) and
Echinochloa colonum
(Poaceae)
J. C. Charris
2
yA. Caselles
1,2
1
Centro de Estudios del Agua, Universidad del Atlántico
2
Research group: Wetlands Caribbean Colombian. Universidad del Atlántico, Km 7 Old way Puerto
Colombia, Barranquilla, 08001, COLOMBIA
Introduction
Horizontal subsurface flow constructed wetlands (HSSF) are an alternative technology to
reduce sewage pollution in small communities and rural areas (Vymazal, 2013). The major
mechanisms for pollutant removal in wetlands include a combination of physical, chemical
and biological processes, where microorganisms, substrate, water and plants carry out the
removal of organic matter, nutrients, pathogens and other pollutants from wastewater
(Kadlec and Wallace, 2009). One of the most studied aspects in these systems has been the
macrophytes in the pollutant removal process. Several studies have reported that these
plants are able to absorb nutrients, carrying oxygen to the root zone and mitigating the
effects of wind and solar radiation on the reactions that occur in water. Several authors
pointed out that there could be a difference in treatment efficiency in relation to plant
species. However, overall, only a small number of species of aquatic macrophytes have
been evaluated in the removal of contaminants in HSSF, such as common reed (
Phragmites
australis
), cattails (
Typha sp
) and sedges (
Scirpus sp
). In tropical regions, although there is
a high diversity of aquatic macrophytes (Velasquez, 1996), little is known about the
removal potential many of these species may have. This research seeks to assess the
potential of local macrophytes:
Cyperus liguralis
and
Echinochloa colonum
in reducing
domestic wastewater pollutants. The experiments were carried out in Universidad del
Atlántico (Barranquilla-Colombia) in a pilot system operating under tropical conditions.
Key words
: COD, ammonium, coliforms, wastewater, biomass, aquatic plants
Methodology
Pilot plant set up of HSSF Constructed Wetlands in the Universidad del Atlántico
Horizontal Sub Surface Flow (HSSF) constructed wetlands consisted of four concrete
containers that were arranged in a parallel configuration. The containers were located near a
wastewater treatment plant that provided service for the university population. Each of the
wetland treatment units measured 1.0×0.6×0.6 m deep and was backfilled with local gravel
substrate (average dimensions of 8 to 10 mm). One set of two wetland beds in series was
planted with 50 seedlings-rhizomes of
Cyperus ligularis
(25 seedlings in each bed) and
another set of two wetland beds in series was planted with 50 seedlings-rhizomes of
Echinochloa colonum
(25 seedlings in each bed). The wetlands were planted in July 2013
and were subsequently monitored for 4 months beginning in August 2013. Clarified
