Abstract
Growing microalgae in tertiary wastewater offers a prospective avenue to remove and re-use the nutrients N and P simultaneously. Moreover, CO2 fixation via microalgae is a potential and promising approach of capturing and storing CO2. The impacts of various nitrogen to phosphorous ratios on the growth, nutrient removal from municipal wastewater, and the bio-fixation of CO2 using Chlorella kessleri were evaluated in this study. For this purpose, the microalgae was grown in synthetic wastewater, similar in composition to tertiary municipal wastewater, with NP ratios of 2:1, 4:1, 6:1, and 8:1 in batch photobioreactors for13 days. Biomass concentration increases at all NP ratios and the maximum biomass concentration is 606.79 mg/L at the NP ratio of 2:1. Nitrogen removal is more than 95% at all NP ratios except at 8:1, where it is only 72.4%. The removal efficiency of phosphorous is significantly affected by the NP ratio. The maximum phosphorous removal is about 97% for the NP ratio 6:1, whereas the lowest removal efficiency of about 20% is at the NP ratio of 2:1. The maximum CO2 bio-fixation rate of 89.36 mgL− 1d− 1 at the end of the first 7 days of the cultivation period is at the NP ratio of 6:1. In this study, Monod growth kinetic model based on a single substrate factor was used and the experimental findings agree well with the predictions by the model.
Simultaneous Biological Nutrient Removal from Municipal Wastewater and CO2-biofixation using Chlorella kessleri
