Physiological study of Chlorella vulgaris in Dairy Industry Effluent

Abstract

Brazil is among the largest producers of milk and derivatives in the world; thus the milk and derivatives industry has great economic importance. Cheese production generates, on average, 9 kg of residual whey for each kg of the product. It is a greasy effluent with a high content of organic materials and inorganic nutrients. Microalgae are physiologically versatile organisms and can exhibit mixotrophic metabolism, making them potential candidates for the remediation of such effluent. The main objective of this project is to investigate the physiology of the microalgae Chlorella vulgaris, a mixotrophic strain isolated from organic waste, in effluent from the cheese production industry. This research is divided into two parts: a preliminary one and the experiment itself. In the preliminary part, the concentration of the effluent to be added to the culture medium and that still will allow population growth will be defined. The preliminary step will be carried out in 96-well microplates and after defining the residue concentration to be used, we will proceed to the algal physiology experiment. For that, C. vulgaris will be cultivated in verticaly positioned tissue culture flasks bubbled with air and under controlled conditions of light intensity and temperature; all determinations will be made in the exponential growth phase. Parameters such as growth rate, dry biomass, chlorophyll a and b concentrations, total carotenoids, biomolecules (lipids, proteins and carbohydrates), and photosynthetic parameters as maximum and effective quantum yield and quenchings, as well as rapid light curves will be determined in 72 h cultures. The expected results of this study include understanding the physiology and possible adaptations of the microalgae C. vulgaris in the effluent contaminated medium. This project has great relevance both from an environmental and economic point of view, as it aims to use an industrial waste effluent as part of culture medium for the cultivation of microalgae. The project will contribute to innovative solutions in waste treatment and the development of more sustainable technologies in the industry.