Carbon Dioxide Strippers
CO2 strippers are necessary water treatment devices for some types of intensive recirculating aquaculture systems. In general, there are two criteria that indicate the need for a CO2 stripper. If the biofilter is not a trickling filter and pure oxygen is the primary source of oxygen then it is likely that a CO2 stripper is necessary. Ultimately it is the sensitivity of the species of fish that will determine the need for a CO2 stripper.
Unlike a biofilter, the entire recirculating water stream does not have to flow through the stripper. Typically, a small side stream is all that is required. Fortunately, CO2 strippers can also assist with the other water quality maintenance chores. The two extra benefits of a CO2 stripper are the addition of oxygen and the extra biofiltration surface area provided by the packing.
The use of CO2 strippers is becoming more common as RAS (recirculating aquaculture systems) become more intensive. Much has been written about the theory of design and sizing but little has been written about the practical aspects of stripper design and construction. This paper will cover the following topics:
- Cross flow versus counter flow operation
- Forced draft versus induced draft air flow
- Pressure distribution systems versus gravity flow distribution
- Solutions for drift elimination
- Design considerations to minimize heat loss
- Media selection criterion