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Removal efficiency of a horizontal subsurface flow constructed wetlands planted with
corn (
Zea mays
) and sesame (
Sesamum indicus
) in a rural zone of Santa Marta, Colombia
A. Caselles
1,2
, A. Hernandez
2
, G. Jimenez
2
y F. Castilla
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
Streams in the rural areas of Santa Marta (Colombia), are being impacted from poorly treated and
untreated domestic wastewater, agricultural fertilizers, and pesticides. Population growth and
increasing tourism compound environmental pressures. Horizontal subsurface flow constructed
wetlands (HSSF CW) are low energy, cost effective, alternative treatment systems which have
the potential to reduce surface water contamination (Kadlec and Wallace, 2009). Food producing
crops can be grown in the gravel medium of a CW reusing the nutrients in the wastewater and the
effluent can be discharged, or used to irrigate crops, gardens, plantation trees, and pastures.
To advance wastewater treatment studies with an emphasis on sustainability, an integrated CW
wastewater treatment facility was designed and constructed on a small farm inhabited by six
residents. The farm is located within the boundaries of the Biological Reserve CAOBA,
(
, in the Sierra Nevada de Santa Marta
(SNSM). The SNSM is a large and ecologically diverse region located in northeast Colombia.
The rational for the design of the integrated CW system for treating septic tank effluent was
based on optimizing land use, treating wastewater with respect to organic matter and pathogens
while promoting water/nutrient reuse via on-site food production, corn and sesame.
Key words
: domestic wastewater, nutrients, organic matter, microorganisms, corn, sesame
Methods
Wastewater treatment system.
An integrated CW wastewater treatment facility was constructed
at the Biological Reserve CAOBA, which is located in the river basin of the Manzanares river, a
tropical region of the SNSM. The treatment system included a septic tank (2.6 m
3
) for primary
treatment, a series of wetland cells (2 subsurface-flow wetland cells of 11 x 1.7 x 0.6 m) to
provide secondary treatment, and two surface-flow wetlands (2m x 1.8m x 0.4m) for polishing
(tertiary treatment) of the wastewater. Each of the subsurface-flow cells were backfilled to a
depth of 0.5 m with screened 12 mm river gravel harvested from the nearby river.
Planting corn (
Zea mays
) and sesame (
Sesamum indicus
).
Seeds of corn and sesame were
germinated in culture flats and grown for 25 days prior to being transplanted into the treatment
system. At the time of transplanting, the plants ranged from 10-15 cm high and were planted on
20 cm centers. Shade from trees interfered with growth in the final portions of the cells. After
approximately 150 days, the corn and sesame biomass, including roots, shoots and fruit were
