Utilization of Anabaena sp. in CO2 removal processes

Abstract

This paper focuses on modelling the growth rate and exopolysaccharides production of Anabaena sp. ATCC 33047, to be used in carbon dioxide removal and biofuels production. For this, the influence of dilution rate, irradiance and aeration rate on the biomass and exopolysaccharides productivity, as well as on the CO(2) fixation rate, have been studied. The productivity of the cultures was maximum at the highest irradiance and dilution rate assayed, resulting to 0.5 g(bio) l(-1) day(-1) and 0.2 g(eps) l(-1) day(-1), and the CO(2) fixation rate measured was 1.0 gCO(2) l(-1) day(-1). The results showed that although Anabaena sp. was partially photo-inhibited at irradiances higher than 1,300 μE m(-2) s(-1), its growth rate increases hyperbolically with the average irradiance inside the culture, and so does the specific exopolysaccharides production rate. The latter, on the other hand, decreases under high external irradiances, indicating that the exopolysaccharides metabolism hindered by photo-damage. Mathematical models that consider these phenomena have been proposed. Regarding aeration, the yield of the cultures decreased at rates over 0.5 v/v/min or when shear rates were higher than 60 s(-1), demonstrating the existence of thus existence of stress damage by aeration. The behaviour of the cultures has been verified outdoors in a pilot-scale airlift tubular photobioreactor. From this study it is concluded that Anabaena sp. is highly recommended to transform CO(2) into valuable products as has been proved capable of metabolizing carbon dioxide at rates of 1.2 gCO(2) l(-1) day(-1) outdoors. The adequacy of the proposed equations is demonstrated, resulting to a useful tool in the design and operation of photobioreactors using this strain.

Impact of CO2 concentration and ambient conditions on microalgal growth and nutrient removal from wastewater by a photobioreactor

“…There has been increasing focus on the use of microalgal culture technology (MCT) for both bio-fixation of CO 2 from flue gases (Adamczyk et al, 2016;Al Ketife et al, 2017;Almomani et al, 2017;Razzak et al, 2013;Toledo-Cervantes et al, 2018;Zhou et al, 2017a;Zhou et al, 2017b) and removal of nutrients from wastewater (AlMomani and Örmeci, 2016;Arbib et al, 2017;Gao et al, 2018;Sutherland et al, 2014;Sutherland et al, 2015;Zhou et al, 2017a;Znad et al, 2018a), with the technical and cost implications of the combined process also recently considered (Judd et al, 2017;Kasprzyk and Gajewska, 2019). The use of biology for carbon capture and direct generation of useful products, predominantly biofuel (Bai and Acharya, 2017;de Godos et al, 2014;Fernández et al, 2012;Kassim and Meng, 2017;Singh et al, 2016;Zhang et al, 2011), obviates the energy-intensive solvent regeneration step of the conventional absorption process for carbon capture (Hammond and Spargo, 2014;Wang et al, 2017;Wilberforce et al, 2019). Moreover, the removal of nutrients from wastewater is considered an essential requirement for the approval of treatment facilities (Almomani et al, 2014;Nourmohammadi et al, 2013).…”

Potential of CO2 capture from flue gases by physicochemical and biological methods: A comparative study

“…Thus, using Anabaena up to 1.0 g/L•day of captured CO 2 was obtained at laboratory scale, it being mainly accumulated at released exopolysaccharides. 55 In terms of photosynthetic efficiency (PE, Eq. ( 5)) an analogous trend is observed because the light provided was the same for all the experiments and the light utilization is proportional to the biomass productivity (Fig.…”

Exploitation of microalgae for biotechnological applications

“…In order to capture CO2 from the flue gas with a CO2 concentration 400 times higher than that of the atmosphere, Botryococcus braunii (Ruangsomboon et al, 2017), Chlorella vulgaris (Pires et al, 2014), Anabaena sp. (Fernández et al, 2012), and Chlorella sp. (Zhao et al, 2011) have been investigated, which CO2 fixation rates can reach 3.05 g CO2 L -1 d -1 .…”