A note on oxygen supply in RAS: The effect of water temperature

Ido Seginer, Noam Mozes

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Two methods of supplying oxygen to recirculating aquaculture systems (RAS) are considered. One is aeration, here by means of airlifts, and the other is pure oxygen, here by liquid oxygen (LOX). Simplified steady-state models are used to compare the performance of these two methods over a range of water temperatures. Biological information for Mediterranean seabreams, as well as engineering and economic information, was obtained from the literature and from practice in Israel. The results, to a first approximation, are: (1) the feed and oxygen consumed by a fish to grow to a certain size are independent of temperature. (2) Supply of oxygen by aeration is controlled by its (minimal) required concentration in the water. As the temperature increases, this concentration approaches the saturation value, thus reducing the driving gradient. (3) Data of required oxygen concentration as a function of temperature are not consistent. Here we assume that for seabreams it is a constant absolute concentration, independent of temperature. (4) The optimal air discharge of an airlift does not depend on the gas to be transferred (oxygen or carbon dioxide), nor on temperature. (5) In operation mode, all available oxygen supplying airlifts should be operated simultaneously at the same air discharge, which together satisfy the oxygen demand. (6) At high temperatures, oxygenation with pure oxygen has a relative advantage over airlifts (aerators), and vice versa. The advantage of airlifts is larger for lower (safer) permissible carbon dioxide levels in the water.

Original languageEnglish
Pages (from-to)46-54
Number of pages9
JournalAquacultural Engineering
Volume50
DOIs
StatePublished - 1 Sep 2012
Externally publishedYes

Keywords

  • Airlifts
  • CO stripping
  • Fish oxygen requirement
  • RAS
  • Response to temperature
  • Seabream
  • Steady-state population

ASJC Scopus subject areas

  • Aquatic Science

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