Biotechnology and Bioinformatics (1+1)

6.2.2.6. Carbon dioxide strippers

• Build up of CO₂ can be a serious problem in a heavily loaded, intensive recirculating system using pure oxygen.
• The choice of biofilter has a direct influence on the degree to which CO₂ is a problem.
• In general, any biofilter other than a trickling filter will have a CO₂ problem when pure oxygen is used rather than compressed air for aeration.
• Building a CO₂ stripper is not a difficult task but it must be included in the overall design of the system.
• In order to remove CO₂, there must be a large interfacial area between air and water. The interfacial area can be increased through the use of subsurface aeration, mechanical surface aerators, spray systems or packed columns. Subsurface aeration is not very efficient and mechanical surface aerators are difficult to use in an intensive recirculating systems. Spray systems can be big energy users and they are not very efficient either. The best choice for intensive and space limited systems is the packed column. Packed columns can be either cross flow or counter flow systems. Packed columns for CO₂ stripping require fans to either force (push) air in or induce (pull) air through the packing.