Simultaneous flue gas bioremediation and reduction of microalgal biomass production costs

Abstract

A flue gas originating from a municipal waste incinerator was used as a source of CO(2) for the cultivation of the microalga Chlorella vulgaris, in order to decrease the biomass production costs and to bioremediate CO(2) simultaneously. The utilization of the flue gas containing 10-13% (v/v) CO(2) and 8-10% (v/v) O(2) for the photobioreactor agitation and CO(2) supply was proven to be convenient. The growth rate of algal cultures on the flue gas was even higher when compared with the control culture supplied by a mixture of pure CO(2) and air (11% (v/v) CO(2)). Correspondingly, the CO(2) fixation rate was also higher when using the flue gas (4.4 g CO(2) l(-1) 24 h(-1)) than using the control gas (3.0 g CO(2) l(-1) 24 h(-1)). The toxicological analysis of the biomass produced using untreated flue gas showed only a slight excess of mercury while all the other compounds (other heavy metals, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and dibenzofurans, and polychlorinated biphenyls) were below the limits required by the European Union foodstuff legislation. Fortunately, extending the flue gas treatment prior to the cultivation unit by a simple granulated activated carbon column led to an efficient absorption of gaseous mercury and to the algal biomass composition compliant with all the foodstuff legislation requirements.

Influence of Different Light-Dark Cycles on Motility and Photosynthesis ofEuglena gracilisin Closed Bioreactors

“…Currently, because of shrinking supplies of fossil fuels and the limited amount of agricultural land that supplies the competing needs of food production and cultivation of plants for technical products such as biodiesel, ethanol, and so on, culturing of microalgae has become a subject of interest. In addition to the production of those products, microalgae offer very interesting possibilities with regard to sewage and wastewater treatment and CO 2 sequestration (Douskova et al, 2009). Currently, many research groups and companies are committing research to microalgae (http://www.oilgae.com).…”

Impacto del CO2 sobre la densidad celular en seis cepas de microalgas marinas

“…Se ha reportado para algunas especies, tolerancia a concentraciones máximas de CO 2 [9,[32][33][34]. Sin embargo, para la especies citadas anteriormente, los mejores rendimientos y productividades se han obtenido con la inyección directa de 5 o 15%v de CO 2 a una velocidad de 0,025vvm (volumen de aire por volumen de trabajo por tiempo), lo óptimo es realizar inyecciones a bajas concentraciones y cortos intervalos de tiempo (por ejemplo 6g/100mL cada 15min), o inyectar altas concentraciones pero a intervalos de tiempo mayores (18g/100mL cada 60min) [35,36]; bajo estas condiciones se han logrado incrementar la productividad de biomasa en un 30% y los rendimientos de biomasa hasta tres veces más [37,38]. Actualmente, se siguen impulsando proyectos dirigidos a utilizar microalgas para la eliminación de CO 2 de gases de combustión, además se busca optimizar la velocidad de fijación de CO 2 mediante selección de cepas adecuadas y la inyección mezclada con el aire.…”

CO2 bioremediation by microalgae in photobioreactors: Impacts of biomass and CO2 concentrations, light, and temperature

“…Thus, the capture of CO 2 represents a 36% (4.0 MJ kg -1 ) CO 2 saving over 11.1 MJ kg -1 CO 2 (bioremediated) of the energy stored as biomass if the CO 2 was theoretically used at 100% efficiency. Experimental CO 2 removal rates were determined by Douskova et al, [80] who used flue gas (10-13% CO 2 ) and controlled gas (11% CO 2 ) to cultivate Chlorella vulgaris. The higher CO 2 fixation rate was achieved using flue gas (4.…”