Abstract—This paper discusses environmental problems of the brewing industry. The literature data on wastewater-purification techniques involving microalgae were reviewed. Brewing-industry wastewaters contain biogenic elements essential for microalgae biomass cultivation: nitrogen, phosphorus, and potassium. Therefore, brewing-industry wastewaters can be used as the basis for a nutrient medium suitable for microalgae cultivation. In the experimental part of this study, effects of various dilution rates applied to the suspension of Chlorella sorokiniana (C) microalgae growing in a nutrient medium containing raw brewing-industry wastewater (RWW) were examined. Three wastewater to microalgae suspension ratios (RWW : C = 70 : 30, 50 : 50, and 30 : 70) were studied to determine the ability of the microalgae to absorb nitrogen and organic and inorganic carbon from RWW and change its pH reaction. Relationships between microalgae growth rates and RWW proportions in the nutrient medium are presented. At RWW : C = 30 : 70, this relationship matches the standard growth curve of a microbial culture. The lag phase, exponential growth phase, and death phase can be distinguished. At RWW : C = 70 : 30, harmful effects of wastewaters on the microalgae growth is clearly manifested: microalgae die on the third day, and the green solution becomes brown, which confirms the death of microalgae cells. It is established that the optimal RWW : C ratio is 30 : 70: the microalgae biomass does not die; instead, it grows well using pollutants for nutrition. The solution color after cultivation remains bright green, which is consistent with the color of healthy cells. At RWW : C = 30 : 70, the wastewater-purification efficiency reaches its maximum: the total nitrogen content decreases by up to 70% and the organic-carbon content by up to 90%. The pH reaction changes from acidic to neutral.
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