Growth performance and nutrient removal of a Chlorella vulgaris-Rhizobium sp. co-culture during mixotrophic feed-batch cultivation in synthetic wastewater

Producción Científica

The subarctic green algal strain Chlorella vulgaris 13-1, newly isolated from Northern Sweden, and its co-occurring bacterium Rhizobium sp. were tested for their ability to produce valuable biomass and remove nutrients from synthetic wastewater during mixotrophic feed-batch cultivation at multiple hydraulic retention times (HRTs = 7, 5 and 3 days). The algal-bacterial co-culture showed better performance compared to the corresponding axenic cultures (HRT = 7 days), with a biomass concentration of 0.63 ± 0.03 g/L and removal rates of 49.5 ± 6.1% TOC, 55.7 ± 8.04% TN and 95.6 ± 3.6% TP at steady-state. Culture stability and a high nutrient removal capacity were recorded in the algal-bacterial co-culture even at HRTs of 5 and 3 days. Interestingly, reducing the HRT from 7 to 5 days resulted in a higher lipid content of the biomass, further reduction of the HRT to 3 days enhanced both daily biomass productivity (1.03 g/L/day) and nutrient assimilation. Mixotrophic co-cultivation of C. vulgaris-Rhizobium sp. can successfully be applied for wastewater reclamation in continuous mode at HRT of 3–7 days, and thus is suitable for both summer and winter conditions in Nordic countries.

Swedish Energy Agency (grant 2018-017772 ; project 48007-1)

Vinnova (grant 2017-03301)

NordForsk NCoE programme “NordAqua” (project 82845)

European Network for Algal-Bioproducts (EUALGAE Cost Action ES1408)

Junta de Castilla y León (project CLU 2017-09)