On the utilization of microalgae for brewery effluent treatment and possible applications of the produced biomass

The effluent of a brewery, complete or diluted with deionised water or with normal culture medium, was used as the growth nutrient medium for Chlorella vulgaris and for a consortium obtained from the autochthonous flora of that effluent (microalgae, cyanobacteria and bacteria). The cultures were exposed to continuous light and aeration, at 25°C, and growth was evaluated by direct counting (C. vulgaris) or by chlorophyll determination (autochthonous flora). Total protein and lipid content, and amino acid and fatty acid profiles in the produced biomass were determined. The highest removal rate of nutrients present in the effluent was obtained when the complete effluent was used as the culture medium for the autochthonous flora - up to 5,855 g kg-1 biomass d-1 of nitrogen and up to 805 g kg-1 biomass d-1 of phosphate. A reduction of up to 27% in biological oxygen demand (BOD5, initial level of 2,172 mg O2 L-1) and up to 15% in chemical oxygen demand (COD, initial level of f mg O2 L- 1) was observed in cultures of the autochthonous flora grown in different loads of effluent. A significant increase in aspartic acid, glutamic acid and valine content, and a higher level of the ramified fatty acids, of the 14:0isobr, 18:4ω3, and the eicosapentaenoic acid, were found in the final biomass obtained from cultures grown with different loads of effluent, compared with the results obtained for the cultures grown in normal nutrient medium. The final microalgae biomass obtained, considering its protein and fatty acid content and the absence of heavy metals in significant amount, can be appropriate for use as animal feed or for biofuel production.