Optimization of Cultivation Condition of Newly Isolated Strain Chlorella Sorokiniana pa.91 for CO2 Bio-Fixation and Nutrients Removal From Real Municipal Wastewater: Impact of Temperature and Light Intensity

Abstract

The cultivation conditions of a newly isolated strain Chlorella sorokiniana pa.91 were optimized for the first time by performing sixty batch cultivation experiments at various temperatures (20, 25, 30 and 35 °C) and light intensities (1000, 3000, 4000, 5000 and 7000 Lux) in three different culture mediums of BG-11, real settled municipal wastewater (RMWW) and synthetic wastewater (SWW). Additionally, to evaluate the capability of C. sorokiniana pa.91 in CO2 bio-fixation and wastewater treatment, the microalgae was cultivated in a flat-plate photobioreactor (CO2 = 16% and 0.6 vvm aeration) under the optimal condition. The optimization results suggested that at the culture conditions of 30 °C, 4000 Lux and RMWW (COD 211 mgL-1) microalgae had the best performance in growth and biomass productivity. Maximum biomass concentration and productivity of 3.21 gL-1 and 0.31 gL-1d-1were achieved, respectively, by cultivation of C. sorokiniana pa.91 in the photobioreactor under the optimized condition. Experimental results showed that C. sorokiniana pa.91 has a high capacity of CO2 bio-fixation (0.59 mgL-1d-1) and CO2 removal rate (35.6 %). Moreover, using C. sorokiniana pa.91 could efficiently remove 74% of NH3, 93% of NO3-, 83% of PO4-3 and 76% of COD from real municipal wastewater after eight days of cultivation in the photobioreactor.