Prediction of dissolved oxygen and carbon dioxide concentration profiles in tubular photobioreactors for microalgal culture

Abstract

Abstract:A model is developed for prediction of axial concentration profiles of dissolved oxygen and carbon dioxide in tubular photobioreactors used for culturing microalgae. Experimental data are used to verify the model for continuous outdoor culture of Porphyridium cruentum grown in a 200-L reactor with 100-m long tubular solar receiver. The culture was carried out at a dilution rate of 0.05 h −1 applied only during a 10-h daylight period. The quasi-steady state biomass concentration achieved was 3.0 g и L −1 , corresponding to a biomass productivity of 1.. The model could predict the dissolved oxygen level in both gas disengagement zone of the reactor and at the end of the loop, the exhaust gas composition, the amount of carbon dioxide injected, and the pH of the culture at each hour. In predicting the various parameters, the model took into account the length of the solar receiver tube, the rate of photosynthesis, the velocity of flow, the degree of mixing, and gas-liquid mass transfer. Because the model simulated the system behavior as a function of tube length and operational variables (superficial gas velocity in the riser, composition of carbon dioxide in the gas injected in the solar receiver and its injection rate), it could potentially be applied to rational design and scale-up of photobioreactors.

Algae for Africa: Microalgae as a source of food, feed and fuel in Kenya

“…Oxygen (O 2 ) is a product of photosynthesis and levels above atmospheric O 2 levels (0.2247 mol O 2 m -3 ) can inhibit photosynthesis in a number of microalgal species, even when the CO 2 levels remain elevated (Aiba, 1982). Furthermore, elevated levels of O 2 coupled with high irradiance can lead to photo-oxidation (Richmond, 1990;Camacho Rubio et al, 1999).…”

Microalgae production in a biofilm photobioreactor

“…Two studies demonstrated CO 2 utilization efficiencies around 70% without significant productivity penalties (Valiorgue et al 2014;Yang 2011). Other studies report CO 2 utilization efficiencies up to 95%, however, the implications for biomass productivity were not quantified (Doucha and Lívanský 2006;Rubio et al 1999). To perform these optimizations, a mathematical model specific for the cultivation system is required, therefore, this model is specific for the Algadisk reactor.…”

“…For microalgae grown in suspended cultures, processes with minimal CO 2 loss have been developed by employing experimentally validated models (Doucha and Lívanský 2006;Rubio et al 1999;Valiorgue et al 2014;Yang 2011). Their primary conclusion is that CO 2 utilization can be improved by increasing the mass transfer from the gas to the liquid (Doucha and Lívanský 2006;Rubio et al 1999;Valiorgue et al 2014;Yang 2011).…”

“…Their primary conclusion is that CO 2 utilization can be improved by increasing the mass transfer from the gas to the liquid (Doucha and Lívanský 2006;Rubio et al 1999;Valiorgue et al 2014;Yang 2011). For microalgal biofilm cultivation, however, processes with minimal CO 2 loss have not been developed, though it has been demonstrated that elevated CO 2 levels are required for maximal productivity Ji et al 2013a;Schultze et al 2015).…”

Dependency of Microalgal Production on Biomass and the Relationship to Yield and Bioreactor Scale-up for Biofuels: a Statistical Analysis of 60+ Years of Algal Bioreactor Data

“…Research on algal production rates for biofuels and commercial products has lead to a plethora of work on open bioreactors, such as ponds and raceway flumes [4,, and closed bioreactors, such as vertical , horizontal [34,40, and helical tubes [97,[143][144][145][146][147][148][149][150][151][152][153][154], flat plates [66,, and other unique designs [133,[185][186][187][188][189]. This research dates back to the early 1950s and was chronicled in a historical perspective by Borowitzka [190].…”