An efficient system for carbonation of high-rate algae pond water to enhance CO2 mass transfer

High-rate algal ponds have the potential to produce 59 T of dry biomass ha−1 year−1 based on the specific productivity of 20 g m−2 day−1. Atmospheric air provides only 5% of the CO2 to the pond surface required for photosynthesis. Hence, CO2 is usually provided via bubbling of concentrated CO2-air mixture into the algae ponds. This process is, however, not significantly effective in terms of mass transfer. Use of bubble column to increase the interfacial area of contact available for gas exchange is proposed as an efficient alternative. A carbonation column (CC) was modeled and designed to measure CO2 absorptivity in-pond water at various pH regimes. The CC performed at 83% CO2 transfer efficiency. An air-to-pond mass transport coefficient of 0.0037 m min−1 was derived. The proposed device can be used with any exhaust gas stream with higher concentrations of CO2 in conjunction with raceways for optimizing algae production.