Investigation of CO2 removal by immobilized carbonic anhydrase enzyme in a hollow-fiber membrane bioreactor

Gas-liquid membrane contactors are compelling candidate bioreactors for implementing CO2 capture because of large mass transfer rates and liquid-solid interfaces, low pressure drop, low axial dispersion and mixing, modularity, simple scale-up or scale-down, and operational suppleness. Binding the carbonic anhydrase (CA) enzyme on the membrane surface adds extra advantages due to the impressive large hydration turnover number and offers an attractive way for CO2 capture. This novel approach to CO2 removal by immobilized CA in a hollow-fiber membrane bioreactor (HFMB) was investigated via a multiscale steady-state model, under gas-filled and partially liquid-filled membrane pores conditions. The impact of CA loading, buffer acid-base constant and concentration, membrane wetting, uncatalyzed/catalyzed CO2 hydration in the wetted membrane zone, operating conditions, and cocurrent/countercurrent flow orientation on the HFMB performance was analyzed. The results showed that this low-cost, green, and environmentally friendly technology could be an appealing alternative to CO2 capture from stationary emissions sources. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 2996-3007, 2017