The study of novelty nutrients supplementary scheme and methodology on advanced carbon sequestration of microalgae

Microalgae has great potential in carbon sequestration and production of biofuel even with a low concentrations of CO2. In this paper, an Andrews based microalgae growth kinetic model and a novel and multiple nutrient supplementary scheme that significantly extends the carbon sequestration period and enhances growth rates of microalgae are proposed. First, the correlation between nutrient concentration and microalgal growth is constructed experimentally. The advanced growth kinetic model incorporating nitrogen and phosphorus consumption is developed. Then, the optimum cultivation conditions including initial nutrients concentration, nutrients supplementary interval and daily nutrients supplementary quantities are obtained in the conical flask reactor. The findings led to a novel nutrient supplementation strategy that initiates with a 0.2BC concentration, followed by a 0.3BC addition at 100 h, with subsequent supplements every 72 h. After adopting this supplementary strategy, the microalgae growth rate is increased by 42.9 % and the carbon sequestration rate is increased by 56.2 % compared with that of the original microalgae cultivation method in one cultivation cycle. Finally, the universal microalgae nutrients supplementary model is proposed in a piecewise model. It can be concluded from the model that in the first cultivation period, microalgae needs a higher affinity for nutrients and after nutrients supplementary, the sensitivity to nutrient inhibition is reduced. The paper is significantly helpful to improve the sustainability of the microalgae growth rate and the carbon sequestration rate.