Valorization of Urban Wastewater (UWW) for Microalgae-based Biotechnology

SCHMUCK, J; RENO, U; MARQUEZ, V; REGALDO, L; KERGARAVAT, S.V.; GAGNETEN, AM

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

Society of Environmental Toxicology and Chemistry

Microalgae-based biotechnology can contribute to the bioeconomy through the production of valuable metabolites. The objective of this work was to know the biochemical composition of Chlorella vulgaris in mixotrophic medium composed of Urban Wastewater (UWW). These were collected from the treatment plant of San Justo city (Santa Fe, Argentina), with a system of stabilization ponds and a chlorination chamber, before discharging in the Salado River. Samples were taken prior to the chlorination chamber and were filtrated and centrifugated, before performing a 72 h algal growth inhibition test. Chlorella vulgaris grew at a maximum concentration of 100% UWW, selected to carry out a 100% UWW Mixotrophic Test (MT) (in triplicated, 1 L flask, inoculum of 105 cells mL-1, 24:0 light:dark 8000 lux at 24 ± 2 °C, pH = 7.0 ± 0.5, aeration and continuous magnetic stirring). The growth curve of C. vulgaris was made and an intermediate time (T1, exponential phase) and a final time (T2, decline phase) were determined. At each time, carbohydrates (C) (Dubois phenol-sulphuric acid method), proteins (P) (alkaline hydrolysis method and quantification by the Bradford method), lipids (L) (sulpho-phospho-vanillin reaction) and fatty acid profile (FAP) (gas chromatography) were determined. For C the difference was significant (p0.05), nor between MT and CT-T2. The highest accumulation of L was achieved at MT-T2: 17.45 ± 3.27 %. FAP obtained was similar in MT and CT mainly composed by fatty acids of 16 and 18 carbon atoms; palmitoleic and oleic acids: 3.20% and 11.47% (T1); 1.39% and 21.70% (T2). Linolenic acids reached a maximum of 17.33% in MT-T1. Linoleic acids are relevant for aquaculture diets because microalgae consumers cannot synthesise them. The cultivation of microalgae in UWW is a tool of the new Circular Bio-based Economy. Where the UWW are valued as raw material to produce biomass of sustainable origin with high value in the marking ofbioproducts.