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Microalgae starvation for enhanced phosphorus uptake from municipal wastewater

Author:
Aigars Lavrinovičs, Linda Mežule, Tālis Juhna
Source:
Algal research 2020 v.52 pp. 102090
ISSN:
2211-9264
Subject:
Chlorella, Desmodesmus, Tetradesmus, ambient temperature, biomass, carbon dioxide, cells, correlation, dissolved inorganic nitrogen, inorganic phosphorus, microalgae, municipal wastewater, pH, research, starvation, strains, wastewater treatment
Abstract:
Three microalgal species, Desmodesmus communis, Tetradesmus obliquus and Chlorella protothecoides were studied for enhanced phosphorus removal from municipal wastewater. Microalgae were first exposed to phosphorus deficit conditions for 7 and 14 days and then inoculated in filtered primary or secondary wastewater from a small municipal wastewater treatment plant at ambient temperature and CO₂ concentration. D. communis and T. obliquus strains showed higher biomass growth rates in secondary wastewater after 7-day starvation period, while C. protothecoides grew better in the same effluent without starvation. All strains were able to achieve nearly complete (>99.9%) removal of dissolved inorganic phosphorus (DIP). Moreover, D. communis and T. obliquus showed ~89% DIP reduction within 24 h after 7-day phosphorus starvation. Dissolved inorganic nitrogen removal for all algal strains did not exceed 50% for any of the treatments. All three strains were able to store excess phosphorus within their cells as polyphosphate and the highest Poly-P content was observed in cultures grown in primary wastewater. Poly-P concentration in C. protothecoides reached 250 μg mg⁻¹. At the same time no correlation between Poly-P and P removal was observed. The efficiency of nutrient (P) removal from municipal wastewater to ultra-low levels (<0.1 mg L⁻¹) is closely linked to algae starvation and auxiliary factors, like environmental pH and N/P ratio.
Agid:
7142846