Nutritive capability of anaerobically digested black water increases productivity of Tetradesmus obliquus: Domestic wastewater as an alternative nutrient resource
Addition of Mn2+, Mg2+ and Fe2+ to digested BW caused maximal growth of T. obliquus.
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At maximal growth of T. obliquus in BW low chlorophyll a content was observed.
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Lipids and starch accumulation was observed in the cells with high productivity.
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Indication of mixotrophic growth of T. obliquus at high organic concentration of BW.
Abstract
Domestic wastewater represents a potential source of nutrients, water and energy. In this study, Tetradesmus obliquus was grown in anaerobically digested black water (BW) to observe growth limitation factors and physiological performances of the algal cells. Supplementing BW with Fe2+, Mg2+, and Mn2+ allowed maximal growth and a significantly higher productivity (0.357 g DW L−1 d−1, compared to the control medium (CM) with 0.302 g DW L−1 d−1) (ANOVA F = 992, d.f. 4,10, p ≤ 0.05) was observed. Interestingly, compared to the CM, only 10% of chlorophyll a concentration was observed at such higher productivity but a two times higher number of resting spore cells (which showed accumulation of lipid and starch granules) were found. The existence of an about 1000 times higher concentration of organic substance in BW than in CM may facilitates a mixotrophic mode and became advantageous for the growth of T. obliquus.
