Influence of elevated CO 2 concentrations on growth, nutrient removal, and CO 2 biofixation using Chlorella kessleri cul
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ORIGINAL PAPER
Influence of elevated CO2 concentrations on growth, nutrient removal, and CO2 biofixation using Chlorella kessleri cultivation M. O. Faruque1,2 · K. A. Mohammed1 · M. M. Hossain1 · S. A. Razzak1 Received: 6 May 2020 / Revised: 30 July 2020 / Accepted: 24 August 2020 © Islamic Azad University (IAU) 2020
Abstract In this study, the ability of microalgae Chlorella kessleri to remove nutrients, biofix CO2, and generate valuable biomass was investigated. For this purpose, C O2 at different concentrations was added to the synthetic tertiary municipal wastewater for cultivating C. kessleri in batch photobioreactors. The concentration of biomass increases gradually during the cultivation period for the tested C O2 concentrations of 2%, 6%, and 10%, except 0% C O2. The highest biomass concentration found was 607 mg/L, and the highest biomass productivity is 46 mg/L/day, at a C O2 concentration of 2%. Monod growth kinetic model based on a single substrate factor was used, and the experimental findings agree well with the predictions by the model for all feed concentrations except 0% C O2. Biofixation of C O2 depends on the optimal C O2 concentration supplied to the culture. The maximum biofixation rate of C O2 achieved at 2% CO2 is 83.88 mg/L/day. The maximum removal of total nitrogen of 99% was achieved for both 2% and 10% CO2, while the total nitrogen removal is negligible by microalgae cultured with air without CO2 enrichment, which confirms the beneficial effect of C O2 on the removal of nutrients from wastewater media. These findings indicate the possibility of nutrient removal from tertiary municipal wastewater using microalgae C. kessleri along with CO2 biofixation. Keywords Algal growth · CO2 biofixation · Kinetic model · Nutrient removal · Wastewater treatment List of symbols OD Optical density BBM Bold’s Basal Medium 𝜇g Specific growth rate 𝜇m Maximum specific growth rate PB Biomass productivity (mg/L/day) X1 and X2 Biomass weight (mg/L) at the time t1 and t2 X0 and Xt Biomass weight (mg/L) at the initial time, t0 and at the end of the cultivation period tt RCO2 CO2 biofixation rate (mg/L/day) Ccarbon Carbon content MCO2 Molecular weight of CO2
Editorial responsibility: Samareh Mirkia. * S. A. Razzak [email protected] 1
Chemical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
Department of Petroleum and Mining Engineering, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh
2
Mc Atomic weight of carbon d Day
Introduction Maintaining a sustainable environment is one of the key goals of all countries around the world. Various anthropogenic activities, resulting in the emission of greenhouse gases (GHGs) and improper disposal of tertiary wastewater (WW) due to over-population and industrialization, are the major processes that pose a pivotal challenge to the environmental sustainability (Arbib et al. 2014). CO2 contributes approximately 52% to emissions responsible for total global
