Abstract

BELTRAN-ROCHA, Julio C; GUAJARDO-BARBOSA, Claudio; BARCELO-QUINTAL, Icela D  and  LOPEZ-CHUKEN, Ulrico J. Biotreatment of secondary municipal effluents using microalgae: Effect of pH, nutrients (C, N and P) and CO₂ enrichment. Rev. biol. mar. oceanogr. [online]. 2017, vol.52, n.3, pp.417-427. ISSN 0718-1957.  http://dx.doi.org/10.4067/S0718-19572017000300001.

This review discusses microalgae assimilation of C, N and P as affected by pH-dependent factors (solubility, ionization state and bioavailability) and CO₂ enrichment in tertiary water treatment during microalgae biomass production. This study indicates the importance of monitoring critical conditions such as: 1) pH and inorganic carbon species interaction; 2) P bioavailability; 3) nitrogen removal through NH₃ volatilization and 4) NH₃ toxicity. Also, optimal CO₂ enriched air considerations, such as: 1) combining intermittent and variable CO₂ enrichment to avoid losses into the atmosphere; 2) preventing microalgae growth inhibition due to H₂CO₃ formation and pH acidification at early stages of the culture and 3) maintenance of optimal pH (≈ 8.5) through the buffer system (CO₂ / HCO₃^_). Finally, we suggest that biological technologies based on microalgae culture to remove excessive nutrient loads and compliance with environmental laws from water, represent a viable alternative attached to recycling and revaluation of resources through the generation and potential uses of biomass (e.g., fertilizer, pigments and antioxidants).

Keywords : Microalgae; MWTP effluents; nutrient recycling; tertiary wastewater treatment.

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