The essential design components in an integrated recirculating aquaculture system or Aquaponics are fish rearing tanks, settable and suspended solids removal, bio filter, horticulture grow space ,sump and additions tank, and a degassing tank.
Fish effluent is directed in to settling tanks and filters to remove fish waste solids. Solids can accumulate an create anaerobic pockets as well as clog pipes. Suspended solids will also coat plant roots which will eventually prevent nutrient uptake and will also starve plants of oxygen.
The three primary types of filtration are gravity separation, filtration and flotation.
Gravity separation includes clarifiers or settling tanks, and hydrocyclones. Swirl filters pictured below are part of this type of filtration.
Filtration removal can be utilized to remove finer particulates from culture water. This can be done by using a screen, using granular media or porous media filters.
Also flotation process uses air bubbles, particulate attaches to the bubbles as they rise from the system and are then separated from the culture water.
Tanks filed with porous material or other media gives nitrifying bacteria a place to colonize. In raft aquaponics there is little growing media for the bacteria to attach. Bacteria do colonize sides and bottoms of grow tanks as well as undersides of the rafts and plant roots. By providing a separate tank for bacteria to break down ammonia to nitrite, plants have a better opportunity to uptake nutrients and remove them from the culture water. Two types of required bacteria; Nitrosmonas and Nitrobacter.
Anaerobic conditions are created in the solids and sludge formed. Toxic gasses form such as hydrogen sulfide, methane and nitrogen. Air diffusers help to vent gasses from the culture water before they reach the plant production area.
Hydroponic Production grow space
Deep troughs 12 to 16 inches are constructed to grow vegetables. In the raft system a rectangular pallet holds vegetables above water line with the roots dangling down below into the water flowing from the fish rearing tanks. Troughs can be made from poured concrete or concrete blocks with a polyethylene liner or tanks made from fiberglass can be used. The University of Virgin Islands aquaculture research center recommends a 11.5 to 1 ratio of grow bed surface area to fish tank surface area in a high density system.
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