The North Auburn Fisheries unit, located in Auburn,
Alabama harvests Nile Tilapia year round. The tilapia
grow to maturity in two adjacent tanks located inside
of a greenhouse to. The winter months make it
difficult to keep the water warm for healthy growth
conditions. Monetary constraints posed by traditional
heating methods creates the need to develop a
sustainable heating system that utilizes the fish
waste at hand.
•Heat tank water from 22˚C to 25˚C through anaerobic
digestion and collection of generated methane.
•Alter agriculture digestion systems for an
aquaculture system.
•Design a completely nature powered and cost
effective system to demonstrate the potential in
green energy.
•Heat tilapia sludge from 22° to 35°C, on cloudy
and sunny days during the winter months.
•Run in batch mode for about 1 hour
•Two solar stills at a time heat the sludge for one
digester
•The solar stills will be filled 3 times a day with 24
gallons of sludge
•Top of solar still can open to allow user to push
leftover sludge into outlet
Methane aquaculture system consists of:
• 4 solar stills
• 5 fixed film anaerobic digesters
• Rain water capture barrels
• Methane burner for heating
This increases the revenue potential of tilapia by
facilitating increased tilapia growth and decreasing
the use of electrical heating. The system also creates
an opportunity to educate future generations on the
potential of sustainable energy.
Dr. Jesse Chappell, Dr. Mark Dougherty, and Dr. Oladiran Fasina.
NORTH AUBURN FISHERIES UNIT: METHANE AQUACULTUREAnnie Gallagher, Steven Major, Bobbi Steenbergen Williams
Biosystems Engineering Department, Auburn University, Auburn, Alabama 36849.
PROBLEM STATEMENT
DESIGN GOALS
Methods
SUMMARY
LOCATION MAP
PROPOSED DESIGN
Acknowledgements
SOLAR STILL DESIGN
COST ESTIMATE
DIGESTER DESIGN
Fixed Film Anaerobic Digester
•55 Gallon, 15° cone bottom tank with removable lid and stand.
•Denim insulation, and black tarp to keep digester temperature
between 32°C and 35°C.
•Fixed film of textured plastic electrical conduit pipe to increase
contact between bacteria and total solids.
•Digesters run in batch mode, with a hydraulic retention time (HRT) of
1 day, and a solid retention time SRT of 10 days.
•Slurry runs through system in updraft mode.
•System of 5 digesters produces 16 meters cubed a day.
Figure 3: Sketch up rendering of Fixed Film Anaerobic Digester.
1. Existing Features: Waste water with 2% solids flows from the Tilapia tanks to clarification basin.
2. Solar Stills: Thickened sludge (5% solids) from the hydrostatic valve are gravity fed into the solar still. The
sludge is heated from 22°C to 35°C.
3. Fixed Film Anaerobic Digesters: Fed every 24 hours with 48 gallons of sludge from the solar stills.
4. Digestate Collection: Digestate from fixed film digesters is collected in a trough to be used as fertilizer.
Figure 2: SketchUp Rendering of Methane Production System
Components Amount
Solar stills $ -254.30
Fixed Film Anaerobic Digesters $ -2.094.10
Pump and piping
(2” PVC Sch. 40 painted with white paint
for UV protection)
$ - 592.19
Cost Saved on Heating
(December- February)
$ 223.39
Increased Revenue from Fish Sold
(December- Februry)
$ 2937.00
Revenue from System Per Year $ 219.80
Table 1: Cost Analysis of system for months that water needs heating,
doe not include maitence, operation, or production
Figure 1: North Auburn Fisheries Unit located north of auburn university
on N. College Street.
Digestate Solids Trough
Liquid Digestate Collection
Educational Board
Solar Stills
Methane Storage
Water HeaterExisting Clarification Basins