45
Sistemas de Humedales para mejorar la calidad del agua
The use of floating wetlands with
Cyperus papyrus
and
Pontederia sagittata
for the
treatment of a polluted urban lake.
E. J. Olguín, G. Sánchez, E. González, J. L. Domínguez, V. J. Hernández, O. S. Castillo.
Biotechnological Management of Resources Network, Institute of Ecology, Xalapa, Veracruz,
México.
Keywords:
Water quality, Phytofiltration, Phytoremediation.
Introduction
“Los Lagos”, located in the City of Xalapa, in Veracruz, Mexico, is a group of three urban lakes
that are eutrophized according to the monitoring study carried out by our research group during
2012 and 2013. Due to such results, a project funded by the local government to reduce the
pollution level of this water body using floating wetlands (FW), was started in August 2013.
These systems use emergent plants supported on a light structure to provide buoyancy that
accumulate nutrients directly from the water column reducing the concentrations of contaminants
(Tanner and Headley, 2011). However, there is scanty information about them and to the best of
our knowledge; there are no applications in México for the treatment of urban lakes. The
objective of the present work was to assess the performance of two linear FWs, established in
Lake #1, using two emergent plants
, Cyperus papyrus
and
Pontederia sagittata
, which have not
been described previously in FWs.
P. sagittata
has been successfully used in the treatment of
sugar cane stillage (Olguín et al., 2008).
Methodology
Plants
. P. sagittata
was collected from a natural wetland located in “Cansaburros” Veracruz,
Mexico (19° 33' 3.64” N; 96° 22' 29.54” O, 26 m.a.s.l.) while
C. papyrus
was obtained from a
local garden center.
FWs.
Two linear FWs were established in Lake #1 with a surface of 17.5 m² for FW1 and 33 m²
for FW2 in mid-September and early November of 2013, respectively. These were built using
boxes and cylindrical containers made of recycled plastic. Four and one individuals of
P.
sagittata
and
C. papyrus
were planted in each plastic box resulting in an average density of
3.41kgdw.m
-2
.
Monitoring.
A monthly monitoring of lake water was carried out since the establishment of the
FWs. Several samples of water column were taken in the front of the FWs and also in the back
of the barrier to evaluate changes in water quality. The inlet stream of the first lake was also
sampled every time. Chemical oxygen demand (COD), Biochemical oxygen demand (BOD
5
),
nitrates (N-NO
3
), ammonia-nitrogen (N-NH
4
), phosphates (P-PO
4
), sulfates (S-SO
4
),
Chlorophyll-a (CHL-A), pH, total dissolved solids (TDS), dissolved oxygen (DO), microcystin in
