Effect of ambient temperature variations on an indigenous microalgae-nitrifying bacteria culture dominated by Chlorella

• Published in: Bioresource technology Vol. 290; p. 121788
• Main Authors: González-Camejo, J., Aparicio, S., Ruano, M.V., Borrás, L., Barat, R., Ferrer, J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-10-2019
• Subjects: Ammonium competition; Chlorella; Microalgae; Nitrifying bacteria; Outdoor; Temperature; Outdoor; Chlorella; Temperature; Microalgae; Nitrifying bacteria; Ammonium competition
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2019.121788

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•Temperatures in the range of 15–30 °C obtained similar performance.•Temperatures over 30–35 °C made microalgae viability reduce.•Maintaining the temperature over 30 °C also favoured AOB activity.•Temperature peaks can trigger AOB growth and limit ammonium in the culture.•Microalgae activity can be recovered after a short temperature peak once it drops.
Two outdoor photobioreactors were operated to evaluate the effect of variable ambient temperature on an indigenous microalgae-nitrifying bacteria culture dominated by Chlorella. Four experiments were carried out in different seasons, maintaining the temperature-controlled PBR at around 25 °C (by either heating or cooling), while the temperature in the non-temperature-controlled PBR was allowed to vary with the ambient conditions. Temperatures in the range of 15–30 °C had no significant effect on the microalgae cultivation performance. However, when the temperature rose to 30–35 °C microalgae viability was significantly reduced. Sudden temperature rises triggered AOB growth in the indigenous microalgae culture, which worsened microalgae performance, especially when AOB activity made the system ammonium-limited. Microalgae activity could be recovered after a short temperature peak over 30 °C once the temperature dropped, but stopped when the temperature was maintained around 28–30 °C for several days.