Transcript BMPs for Aquaculture, Swine and Poultry Production

BMPs for
Aquaculture Production
Lori Marsh, Associate Professor,
Biological Systems Engineering,
Virginia Tech
September 19, 2005
Aquatic Animal Production
(CAAP/AAP) Systems:
•
•
•
•
•
Flow-through
Recirculating
Net pen and cages
Ponds
Lobster pounds, Crawfish, Shellfish,
Aquariums, and Alligators
Flow-through Systems
•
•
•
•
•
Constantly flowing culture water
Commonly use raceways or tanks
Found throughout US
Require consistent volume of water
Most use well, spring or stream water as
source
• Primary method to grow salmonid species
such as rainbow trout.
Recirculating Systems
• Highly intensive culture
• Actively filter and reuse water
• Water treatment including
– Ammonia removal
– Solids removal
– Oxygenation
– Temperature control….
• Capital intensive at startup
Net Pens and Cages
• Suspended or floating holding systems
• Located along a shoreline or pier or
anchored off shore
• Rely on natural water movement to assure
water exchange/quality for fish
What’s the Problem with CAAPs?
• 4,200 commercial facilities (1998 USDA
census)
• Water quality concerns include
– Suspended solids, P, NH3, BOD
– Drugs (e.g. oxytetracycline or formalin)
– Chemicals (e.g. copper-containing pesticides)
– Pathogens (primarily a concern for native
biota)
BMPs for Feed Management
•
•
•
•
•
Applicable to all systems
Avoid overfeeding
Match feeding to feed requirements
Direct feed to fish
Use quality feed, and store to reserve nutrient
quality
• Handle feed to minimize fines
• Active feed monitoring (net pens): detects when
feed pellets are passing below fish.
BMP for Removal of Solids in a
Flow-through System
• Quiescent Zones typically constructed with
wire mesh to exclude fish from last 10% of
raceway.
• Designed to insure that overflow rate is
smaller than particle settling velocity.
• Solids typically removed by suction
through a vacuum head.
Other BMPs for Solids Removal
• Sedimentation basins
– Off-line settling (OLS) basins receive water and solids
slurry from Quiescent Zone (QZ).
• Note: QZ + OLS are most common settling system for flowthrough systems.
– Full-flow settling (FFS) systems stand alone and
collect water flow from entire facility (need 2 operating
in parallel for solids removal).
• Secondary Settling
– Microscreens
– Vegetated ditches
– Constructed wetlands
Solids Disposal
• Dewatering
– Natural evaporation
– Mechanical assistance
•
•
•
•
•
Filtration
Squeezing
Capillary action
Vacuum withdrawal
Centrifugal
– Chemicals are often added to assist with the
dewatering process
Solids Composting
• Dewatered sludge mixed with bulking
agent to add carbon, reduce moisture,
increase aeration
• Must be aerated (turned or by adding air)
• Often screened to remove bulking agent
– Advantages: reduces volume, stabilizes
material, heating destroys pathogens, value
added product
Vermicomposting of solids
VERMICOMPOST
WORMS
Vermicomposting uses earthworms to
transform organic wastes and results in two
saleable products: vermicompost and worms.
WHY CONSIDER
VERMICOMPOSTING?
Two saleable products
Possibility of worms as fish feed
Worm composting faster than microbial
Worms turn the material so
machines/people don’t have to
Vermicomposting suitable for highmoisture waste
HYDROCLONE
After settling, the
contents were run
through a
hydroclone.
WORM BINS
The bins in operation
WORM
SEPARATOR
Material from beds
was run through a
trommel screen
resulting in
screened material,
unscreened
compost, and
worms.
CONCLUSIONS
Processing rate very slow during
extreme temperature conditions >29 C
or < 10 C; therefore an unconditioned
greenhouse does not appear suitable
for this process.
During more optimum temperature
conditions, worms processed 2.3 kg dry
sludge/m2-week.
For the estimated sludge production at
BRA, a 30.5 m x 91.5 m (100’x300’)
structure would be required to house
sufficient worm beds.
Land Application of Solids
• Can land apply without dewatering
– Hydraulic limitations not nutrient
• Need provisions for times of frozen ground
• BMPs for land application of animal
wastes would apply, e.g. site conditions,
weather, crop nutrient uptake, application
rates, land availability, setbacks, slopes,
neighbors, etc.
Waste Treatment Options for Effluent
• POTW
• Lagoons: BMPs for lagoons apply, e.g. site
selection, design, start up, maintenance,
record keeping, clean water diversion, etc.
Mortality Management
• Avoid disease outbreaks
• Inspect daily, remove mortality promptly
• Proper disposal—composting, rendering
BMPs for Ponds
• Avoid discharges e.g. seine harvest rather than draining;
maintain freeboard for storm volume, drain from top
when necessary.
• Implement erosion control for pond ( protection from
waves, aerators, vehicles, etc.) and watershed.
• Manage rainwater: divert excess runoff,
• Maintain good vegetation and avoid livestock production
in watershed.
• Use drugs and chemicals only as needed, use only FDAand EPA-approved water quality enhancers and follow
label directions carefully.
Constituents of concern
• Nutrients
• Bacteria (?)
– Carr, O.J. and R. Goulder. 1993. Directly counted
bacteria in a trout farm and its effluent. Aquacult. Fish.
Manage. Vol 24, no. 1, pp. 19-27.
• Pharmaceuticals (?)
– Halling-Sorensen, B. et al. 1998. Occurrence, fate
and effects of pharmaceutical substances in the
environment—A review. Chemosphere. Vol 36, no.2,
pp. 357-393. Jan. (Nice abstract. Unfortunately,
article is in German.)
References
• Claude E. Boyd. Guidelines for
aquaculture effluent management at the
farm-level. Aquaculture. Vol 226 Issues 14, Oct. 2003. pp 101-112.
• USEPA. BMPs for CAAP Facilities.
www.epa.gov/guide/aquaculture.