Post on 20-Dec-2015
Using aquatic plants to remove nutrients from
aquaculture wastewater
How does aquaculture introduce nitrogen into the
environment?
• Fish feeds contain nitrogen compounds
• large amounts of waste
Mechanisms to reduce nitrogen
• Traditional separation machinery
• settling ponds
• Constructed wetlands
• hydroponics
Case Studies
Lin et al. (2003)
ammonia 57%, nitrite 90%, nitrate 68%
Mississippi State University
Ammonia 63%
Nitrite 97%
Nitrate 80%
Giant Salvinia (Salvinia molesta)
Experimental Design
• 4 aquaria all containing 30g tilapia
• 2 of the 4 aquaria containing Giant Salvinia
• water quality parameters (ammonia, nitrite, nitrate) measured weekly
• difference in nitrogen levels between tanks with aquatic plants and those without?
Nitrite
00.5
11.5
22.5
33.5
44.5
1 2 3 4 5
Test #
Nitr
ite le
vel tank 1
tank 2
tank 3
tank 4
Nitrate
0
20
40
60
80
100
1 2 3 4 5
Test #
Nit
rate
leve
l tank 1
tank 2
tank 3
tank 4
Ammonia
0
0.2
0.4
0.6
0.8
1
1 2 3 4 5
Test #
Am
mo
nia
leve
l
tank 1
tank 2
tank 3
tank 4
Conclusions/Experimental modifications
• Salvinia may be able to effect nitrogen at very low concentrations
• No effect at higher concentrations• Questionable for use in aquaculture
• Light for Salvinia• replications• extend length of experiment
References
• Posadas, B.C. 2003. Use of constructed wetlands to improve water quality in finfish production. Mississippi State University. http://www.msstate.edu/dept/crec/cwres.html
• Lin, Y-F., Jing, S-R., Lee, D-Y. 2003. The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture. Environmental Pollution. 123: 107-113.
• Seawright, D., Stickney, R., Walker, R. 1998. Nutrient dynamics in integrated aquaculture-hydroponics systems. Aquaculture. 160: 215-237
Photos• Michael, J. H. Jr. 2003. Nutrients in salmon hatchery wastewater and its removal through
the use of a wetland constructed to treat off-line settling pond effluent. Aquaculture. 226: 213-225
• Tilapia:www.sun.ac.za/kie/unistel/ aquaculture/aquastel/• Catfish: www.fish2go.com/info6.htm• Constructed wetland: http://www.msstate.edu/dept/crec/cwres.html• Shrimp: whyfiles.org/025chem_weap/ 7.html• Aquaponics(1): http://www.hamburger-umweltinst.org/biomass/mnlwide/img33.gif• Aquaponics (2): www.aquaranch.com/ aquapon.html• Salvinia: http://www.wapms.org/images/salvinia2.jpg