The effect of gas emissions components on the growth of Chlorella vulgaris microalgae

Abstract

The annual growth of environment anthropogenic impact, in particular, the increase of gaseous emissions amount leads to the need of their disposal. A promising solution for this problem may be the use of microalgae to absorb carbon dioxide and oxides of nitrogen and sulfur. It is important to determine the cultivation conditions for further establishment of rational parameters for the gaseous emissions disposal, which will increase the profitability of the process, reduce environmental pollution and obtain biomass for further use. The aim of the work is to analyze studies of the gaseous components impact on the growth and development of microalgae Chlorella vulgaris. The task is to determine the effect of oxides of carbon, nitrogen, sulfur and gaseous emissions on the growth and development of microalgae Chlorella vulgaris. The typical composition of gaseous emissions from a coal-fired thermal power plant based on water vapor, oxides of carbon, nitrogen, and sulfur, which can be assimilated by microalgae cells, is considered. Carbon dioxide in this mixture is 12±2 %, which is a rational concentration for growing biomass of adapted strains. However, when applying a high concentration of CO2 to the culture medium, it is necessary to stabilize the pH, because increasing the carbon dioxide content in the culture medium leads to acidification, while the consumption of CO2 by microalgae in photosynthesis increases the pH value. It is determined that nitrogen oxides, the main part of which is NO, in concentrations up to 100 ppm contribute to the accumulation of biomass and synthesis of nutrients in cells. It is necessary to reduce the concentration of sulfur oxides to 60–100 ppm and avoid their gradual accumulation, as this leads to acidification of the environment and cell death. When using Chlorella vulgaris to purify biogas from CO2 and H2S, the concentration of hydrogen sulfide should not exceed 100 ppm to eliminate its inhibitory effect on cell growth.