Carbon Dioxide In Recirculating Aquaculture Systems

The removal of carbon dioxide in Recirculating Aquaculture Systems (RAS) has been an important topic of research due to the increasing amount of recirculating aquaculture systems being employed in the aquaculture industry. Carbon dioxide, as well as ammonia, are excreted by the fish and can be present in high quantities. Elevated levels of CO2 accumulation within the recirculating water could have toxic effects on fish. The maximum level of CO2 and ammonia that can be present in the tanks depends on the species of fish being farmed. Ammonia is typically removed through a nitrification process. Currently, the most common method of CO2 control in RAS is through the use of aerated packed columns (Timmons, Ebeling, Wheaton, Summerfelt, & …show more content…
(2000) and Hu (2011) looked into controlling the levels of CO2 through the use of chemical additives. Hu (2011) concluded that this method could have negative side effects on recirculating aquaculture systems. The use of paddlewheel and submerged aerators for CO¬2 control was investigated by Eschar et al. (2003). He found that paddlewheel aerators are more efficient than the submerged aerators. Wills et al. (2016) questioned the use of sand filled fluidized beds as a method of CO2 control in RAS systems but found that even if they aid in the control of CO2, fluidized beds alone are not a sufficient method of removal. The use of air-lift pumps for carbon dioxide removal was studied by Moran (2010) and it was found that the CO2 removal efficiency was less than 40%. These results differ greatly from results obtained from Loyless and Malone (1998), outlining that further work needs to be done in this area. Colt et al. (2012) stated that more research should be completed not only on air-lift pumps, but also on CO¬2 removal in weirs and moving bed …show more content…
Little work has been done on determining a design methodology for sizing a moving bed biofilter. In 2007, Gürken Sin developed a dynamic model to predict the ammonia removal rate of nitrifying moving bed biofilters. His model could help one optimize moving bed biofilters but the initial design and sizing of the moving bed biofilter would have to be completed using rules of thumb and past experience. Lin (2008) also developed a mathematical model that would aid in predicting the ammonia utilization, as well as the nitrate and organic carbon utilization in a moving bed biofilter. This model could also aid in optimizing previously designed moving bed biofilters. The need to optimize the design of moving bed biofilters would be eliminated if accurate sizing parameters for the biofilter were