Recirculating Aquaculture Systems - RAS

In-Situ Stringed Bed Suspended Bioreactor (SBSBR)

The reactor has four components such as

  • The outer fiberglass shell with conical bottom.
  • Inner cartridge comprising Perspex framework and plastic beads on string.
  • Airlift pump, and
  • Black lid at top with perforations.

In-Situ Stringed Bed Suspended Bioreactor (SBSBR)

On suspending the reactor one foot below the water level on a float, and operating the airlift pump, water enters the reactor through the perforations on top of the black lid, passes through the cartridge and flows out. When water comes in contact with the immobilized bacteria on the surface of the beads, nitrification takes place and dissolved ammonia in the water is converted to nitrates and subsequently into elemental nitrogen and oxygen. The framework of the inner cartridge is made in such a way that larvae, plankton, and food particles when enters, pass out through the airlift pump without mutilation and damage.Stringed Bed Suspended Bioreactor contains 1001 beads with a surface area > 684cm2.

Biological Specifications

Water Salinity Range 0, 15, & 30 ppt (+/- 5 ppt)
Three different cultures are available for the above mentioned salinity levels
Temperature Tropical conditions-needs no heating and chilling
Cold condition - needs heating and chilling
Total surface area of media 684cm²
Purification capacity 500 litres/day
TAN removal rate 0.88gTAN/ m²/Day
TNN removal rate 0.84g TNN/ m²/Day
Level of Dissolved Oxygen 5.8 – 6.0 ppm
Nitrate level < 8ppm
Backwash Gentle rinsing once a day
Durability Continuous recirculation keeps the system viable with sufficient aeration and ammonia loading

Technical Specifications

  • Acrylic outer shell &Top cover with I – bolts and locknuts
  • Cartridge placed inside outer acrylic shell with gravitational airlift tube arrangement.
  • Bio-media – Beads with micro perforations. Beads are stringed on inner cartridge
  • Conical shaped bottom used for solid waste collection.
  • Plastic float with string. Helps the reactor float in water.
Why Recirculating Aquaculture Systems

Aquaculture hatcheries currently use the open larval rearing system. The open larval rearing systems have been found to have certain shortcomings. These are illustrated in the figure below and explained subsequently.

In an open larval rearing system in a hatchery, there is continuous exchange of seawater on a regular basis. The quantum of exchange varies depending on the hatchery and could be as high as 100%. Due to the heavy demand of seawater in the production...


Recirculating Aquaculture Systems (RAS)

Recirculating aquaculture systems, or RAS, are closed-loop production systems that continuously filter and recycle water, enabling large-scale fish farming that requires a small amount of water and releases little or no pollution.

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