Biofloc

Biofloc Technology and Application to Marine Shrimp Aquaculture

Biofloc technology System design and management Application to marine shrimp Doug Ernst
NaturalShrimp AquaFarm.com

Pacific Aquaculture Caucus. Integrated Multi-Trophic Aquaculture Workshop. Sept 14-15, 2010, Peninsula College, Port Angeles, WA
© Douglas H. Ernst (2010)

Further Reading
Waddell Mariculture Center (SouthCarolina) Texas Agricultural Experiment Station Clemson University Dept. of Agric. & Biol. Engin. (SC) Gulf Coast Research Lab (Univ. S Mississippi) Oceanic Institute (Hawaii) Global Aquaculture Advocate (www.gaalliance.org) Dr. Yoram Avnimelech (Israel Institute of Technology) Biofloc Workgroup Aquacultural Engineering Society www.aesweb.org

Animal Aquaculture Food Conversion
Fish 70% 67.0%FCE 22.3% FCE 1.5 FCR 4.5 FCR Feed

(for non-biofloc systems) Wet and dry weight food conversion

Moisture content: 10% Wet weight FCE: Dry weight FCE:

3X factor

Food conversion and “waste”

Wet wt fish: 1.0 kg feed 0.67 kg fish + 0.78 kg metabolites & solids Dry wt fish: 1.0 kg feed 0.22 kg fish + 0.78 kg metabolites & solids Protein nitrogen conversion (aquaculture average)

Shrimpprotein utilization efficiency: 20% Fish protein utilization efficiency: 25% 70-80% of nitrogen in feed is converted to ammonia (direct & via bacteria)

Biofloc Technology (BFT)

BFT is the utilization of microbial processes within animal rearing units to treat water and provide food resources.

BFT is used to Reduce Reduce water feed

Fish/Shrimp Rearing Unit •Internalized water treatment• “Waste” Biofloc food resource

Reduce waste

Reduce treatment

BFT: Advantages, Disadvantages, Issues

Advantages

Increased food and nitrogen conversion

Reduced water consumption, waste production, and treatment Simplification and cost reduction of facility design Improved environmental control and pathogen biosecurity

Disadvantages

Conditioning time for system start upOxygen consumption of biofloc Energy requirements for maintaining biofloc in suspension

Unique maqnagement issues

Maintenance of desired biofloc density, C/N ratio, and ecology Control of beneficial and harmful bacteria

Biofloc System: Tilapia
Clarification & denitrification

Feed: 32% protein Tilapia: final density 20 kg/m3

1

2

3
1. Clarifier effluent 2. Culture tank water 3.Sludge from clarifier
From Rakocy et al (WAS 2010) University of the Virgin Islands Agricultural Experiment Station

Biofloc System: Semi-Intensive Shrimp

Taw et al, Indonesia WAS 2009

Components of Biofloc

Components of biofloc

Solids: Inorganic and organic particulate solids

Bacteria and fungi: Heterotrophic and chemoautotrophic

Algae: Photoautotrophic and heterotrophicMicro-organisms: protozoa (amoebas, ciliates), nematodes, zooplankton.

BFT in a context of IMTA

The biofloc community and culture animal comprise a multi-trophic ecosystem:

Bacterial-detrital and photosynthetic food chains

Filter deeding detritivores and herbivores

Predator-prey relationships.

Biofloc Components: BDA

Bacterial-detrital aggregate (BDA) Combined cocci. rod, &filamentous bacteria Floc particle size 10 – 1000+ um
100 um

Ray et al, WAS 2009 Hargreaves and Wong, WAS, 2007

Biofloc Components: Algae

Pelagic and benthic diatoms, various green and BG algae

Kent et al, WAS 2010

Kent et al, WAS 2010

www.ucmp.berkeley.edu

LCB stain

Biofloc Components: Micro-organisms

Ciliated protozoan

Nematode

Daphina

Hydroid Planaria ?Vorticella

Biofloc System: Nutrient Pathways
Feed Ammonia Fish / Shrimp POC PON Food/nutrients Biofloc community Heterotrophic bacteria Nitrite Nitrifying bacteria

Fish/Shrimp Culture Tank

Microalgae

DIC DIN DIP

Nitrate

Biofloc removal: Denitrification:

Solid clarifiers & fractionators NO3 N2 and Alkalinity

Whole facility: 1.N & P removal: Macroalgae or halophytes 2.N...