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![Photo: Iris plants growing on floating mats in fishery waste water. Link to photo information](https://webarchive.library.unt.edu/eot2008/20090509201608im_/http://www.ars.usda.gov/is/graphics/photos/jan09/d1292-1i.jpg) Irises can filter
nutrients out of a fishery's wastewater so the water can be returned to ponds
for reuse. Click the image for more information about it.
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Floating Vegetative Mats May Help Clean Fishery
Wastewater
By Sharon Durham January 29, 2009
The feasibility of using floating vegetation to remove nutrients from
fishery wastewater is being tested by Agricultural Research Service (ARS)
scientists.
The researchers' long-term goal is to develop a system to treat
the wastewater, return it to ponds for reuse, and use the nutrients to produce
biomass or plant material. The floating mats act as filters to remove the
nutrients from the water.
The study participants are soil scientist
Robert
K. Hubbard at the
ARS
Southeast Watershed Research Laboratory, in Tifton, Ga.; plant geneticist
William
Anderson and plant pathologist
Jeffrey
P. Wilson at the
ARS
Crop Genetics and Breeding Research Unit, both in Tifton; and University of
Georgia animal science associate professors Gary Burtle and Larry Newton, also
in Tifton.
Wastewater from the fish-production ponds is pumped into 340-gallon
aquaculture tanks. Each tank has a 10-foot-square floating mat on which the
vegetation grows.
The first objective is to find plant species that grow well in fishery
wastewater. Twelve different plant species are currently being tested: St.
Augustine grass, Tifton 85 bermudagrass, common bermudagrass, canna lilies,
iris, bamboo, bulrush, cattail, bordergrass, napiergrass, reeds, and
maidencane. According to Hubbard, the iris is the best performer so far.
The second part of the study--set to begin in the spring of 2009--will
determine the effects of the vegetation on water quality and the amount of
nutrients removed when plant biomass is harvested.
The plant material will be harvested on an as-needed basis and the
plant tissue analyzed for nitrogen, phosphorus, and potassium. Harvested plant
material has several potential uses: It can be transplanted, used as feedstock
for energy production, or composted and used as a soil amendment.
Read more
about this research in the January 2009 issue of Agricultural Research
magazine.
ARS is the principal intramural scientific research agency in the
U.S. Department of Agriculture.