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THE POTENTIAL OF WETLANDS FOR TREATMENT OF MARINE AQUACULTURE EFFLUENTS
AQUACULTURE TODAY
Fastest growing food producing sector worldwide
80% seafood consumed in the US imported
Half from foreign aquaculture!
US marine aquaculture only 1.5% domestic seafood supply
Growth potential, but…
Limited domestic industry due to environmental restrictions
Prohibitively high cost for appropriate sites currently
NOAA Technical Memorandum NMFS F/SPO‐100
MARINE AQUACULTURE:LIMITATIONS
Location, location, location
Seawater source
Cost of land
Competition for space too
Waste management
Recirculating aquaculture
Aids in moving inland to reduce:
Land cost
Resource consumption
Effluent Management is key!Mote Marine Laboratory
LIMITATIONS:EFFLUENT MANAGEMENT
Discharge or reuse
Reuse research lacking
Resource conservation
Where to discharge?
Nutrient limitations
Need “eco‐friendly” filtration
Unit‐process approach
Aerobic/Anaerobic biological filtration
Natural‐type filtration
Constructed wetlands
Marine Aquaculture Research Center:Waste treatment systems
CONSTRUCTED WETLANDS:EFFLUENT TREATMENT ALTERNATIVES
What is a constructed wetland?
Low cost treatment
Low maintenance too!
Wetland “types” based on water flow regime
Free water surface (FWS)
Subsurface flow (SSF)
Constructed wetlands effective “eco‐reactors” Loma Alta Shrimp Aquaculture
CONSTRUCTED WETLANDS:
TYPES AND FUNCTIONS
FWS (“Lowland”)
Anaerobic sediments
Constituent removal area specific
TSS, BOD/COD, N, P
SSF (“Upland”)
Aerobic and/or anaerobic sediments
Convert and/or remove nitrogen species
Constituent removal
TSS, BOD/COD, PVymazal, 2007
CONSTRUCTED WETLANDS:
PLANTS Role of plants
Medium for biofilm attachment
Gas transport to/from sediments through lacunal structure
Little direct nutrient removal or storage by plants
Selection based on:
Native species
Salinity
Flooding regime
Availability
Sleepy CreekMarshallberg, NC
CASE STUDY:LOMA ALTA SHRIMP
AQUACULTURENEAR PORT MANSFIELD, TX
8.1 ha (~20 ac) shrimp farm
Mesohaline (3‐8 ppt salinity)
Produce 10‐15 MT Litopenaeus vannamei
13,600 m3 d‐1 (3.6MGD) effluent
7.7 ha (~19 ac) of constructed wetland
Constant recirculation
Constituent reductions:
TP: 31%, TSS: 65%, ISS: 76%
BOD < 9 ppm, TAN < 1.8 ppm, NO3‐1‐N < 0.42 ppm
CASE STUDY:LOMA ALTA SHRIMP
AQUACULTURE
Using the k‐C* model
1st order removal rate eqn
Target levels (NPDES) could be attained when CW operated as recirculation filters
Pond SA : Wetland SA 12:1
New models
“Tanks in series” approach
C* still applies
SUMMARY
Potential for effective nutrient removal prior to discharge
Low maintenance
Low cost – Requires full‐cost analysis
Accounts for environmental costs too!
Value added products
Internalizing environmental costs improves:
Marketing
Local ecosystems
Public relations
More high salinity research needed for marine aquaculture
MARINE AQUACULTURE RESEARCH CENTER
Marine aquaculture effluent treatment
Evaluate new technologies
Model conventional treatment process
All studies replicated in triplicate
Goal: Prevent detrimental environmental impact on local waterways by marine aquaculture through effective waste management
MARINE AQUACULTURE RESEARCH CENTER
QUESTIONS
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