Nutrient Dynamics in Aquaponics

25 Pages·2017·1.55 MB·English

by  Information Technology

Nutrient Dynamics in Aquaponics
Chris Hartleb
University of Wisconsin-Stevens Point
Northern Aquaculture Demonstration Facility
Aquaponics Innovation Center
Aquaponics
• Integrated & soilless • Initial costs
• Free of biocides – Loans & financing
• Conservative use of water, space & • Location
labor
– Zoning & permitting
• Produces both vegetable & protein crop
• Market
• Continuous year-round production

• Meets socio-economic challenges
– Urban & peri-urban
– Locavore movement
Aquaponic Systems
Fish tanks
Raft tank
Water pump

Clarifier
(solids filter) Degassing tank
Mineralization tanks
& biofilter
Air pump
Plant Production Systems
• Raft (Revised agriculture float technology)
– Deep water culture
• Large volume water
• Root aeration
• Nutrient uptake: High
• Nutrient film technique
– Low volume water
– Less system stability
– Nutrient uptake: Low
• Media based
– Biofiltration in media
– Clogging & cleaning present
– Nutrient uptake: High
Element Concentration (ppm) Percent
Plant Nutrition
Nitrogen 15,000 1.5
Potassium 10,000 1.0
Calcium 5,000 0.5
• Macro-nutrients
Magnesium 2,000 0.2
• Micro-nutrients
Phosphorus 2,000 0.2
• Must be in fish food or water
supply Sulfur 1,000 0.1
Chlorine 100 <0.1
Iron 100 <0.1
Boron 20 <0.1
Manganese 50 <0.1
Zinc 20 <0.1
Copper 6 <0.1
Molybdenum 0.1 <0.1
Nickel 0.1 <0.1
Solids Filtration
 Sources
 Fish wastes
 Uneaten food
 Types
 Settable
 Suspended
 Fine and dissolved
 Settable solids (gravity removal)
 Settling tank
 Hydrocyclone (swirl separator)
Aquaponic Mechanics
Fish Plants
• Feeding rate ratio: 60-100 g/day/m2 Organic (protein) Nitrogen
Potassium Potassium
(leafy greens grown on rafts)
Calcium Calcium
• Nitrification
Magnesium Magnesium
• Mineralization
Phosphorus Phosphorus
• Why does it work? Similarities Sulfur Sulfur
Chlorine Chlorine
Retained in Tissues
Food Sodium
30% N
100% N Iron Iron
32% P
100% P 87% Overlap Boron
Manganese Manganese
Zinc Zinc
Copper Copper
Solids Dissolved Molybdenum Molybdenum
Effluent
13% N 87% N Nickel Nickel
70% N
60-90% P 10-40% P Iodine, Cobalt, Fluorine, Vanadium, Chromium,
68% P Selenium, Tin, Silicon
Biological Filtration
• Nitrification
– Oxidizes ammonia and nitrite to nitrate
– No light needed (photosensitive)
– Oxygen required
– Slimy, light brown, no bad odor
1½ O 1½ O
NH 2 NO - 2 NO -

3
2 3
Ammonia-oxidizing bacteria Nitrite-oxidizing bacteria
(AOB) (NOB)
4.3 g O and 7.14 g alkalinity as CaCO needed to oxidize 1.0 g NH -N
2 3 3
Nitrogen Conversion
• Bacteria convert ammonia to nitrite to nitrate.
– Ammonia-oxidizing bacteria (i.e. Nitrosomonas):

55NH + + 76O + 109HCO - → C H O N + 54NO - + 57H O + 104H CO
4 2 3 5 7 2 2 2 2 3

• Ammonium is combined with oxygen & hydrogen carbonate to produce
nitrite, water & carbonic acid.

– Nitrite-oxidizing bacteria (i.e. Nitrobacter):

400NO - + NH + + 4H CO + HCO - + 195O → C H O N + 3H O + 400NO -
2 4 2 3 3 2 5 7 2 2 3

• Nitrite is combined with ammonium, carbonic acid, hydrogen carbonate &
oxygen to produce water & nitrate (nitrification).