Pilot-Scale cultivation of microalgae in blended effluents: C/N ratio management to boost biomass and biofuel precursors

Saleme Aona de Paula Pereira, Alexia; Silva, Thiago; Magalhães, Iara; Santos, Weller Gabriel da Silva; Oliveira, Mateus Soares de; Reis, Alberto; Couto, Eduardo de Aguiar; Calijuri, Maria Lucia

http://hdl.handle.net/10400.9/6155

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Authors

Saleme Aona de Paula Pereira, Alexia

Silva, Thiago

Magalhães, Iara

Santos, Weller Gabriel da Silva

Oliveira, Mateus Soares de

Reis, Alberto

Couto, Eduardo de Aguiar

Calijuri, Maria Lucia

Abstract(s)

ABSTRACT: Algal biotechnology offers a sustainable pathway for wastewater treatment and resource recovery. However, the low carbon-to-nitrogen (C/N) ratio in domestic wastewater often limits microalgal productivity, which may compromise process viability and, consequently, limit its application in bioproduct valorization routes. This study evaluated the effects of blending municipal wastewater (MW) with industrial wastewater from juice processing (IWJ) at different ratios on biomass production, biochemical composition, and pollutant removal. Pilot-scale experiments in outdoor high-rate algal ponds, operated without external carbon dioxide (CO2) supply (relying on inorganic carbon present in the wastewater and passive diffusion from air). These experiments tested three blends: T1 (60 % MW + 40 % IWJ, C/N 9.25), T2 (40 % MW + 60 % IWJ, C/N 25.31), and T3 (20 % MW + 80 % IWJ, C/N 52.71). T1 achieved the highest biomass productivity and lipid content (14.44 %, p < 0.05), while T3 presented the highest levels of saturated fatty acids C16:0 (40.39 %) and C18:0 (10.08 %), supporting its biodiesel potential. Carbohydrate accumulation was enhanced in T2 (18.44 %) and T3 (21.09 %) under nitrogen-limited conditions. Microalgal species composition varied significantly with the C/N ratio, indicating selective adaptation. Additionally, dissolved organic carbon removal followed first-order kinetics across treatments, confirming model applicability. These findings underscore the effectiveness of effluent blending and C/N adjustment to enhance biomass quality, pollutant removal, and suitability for biofuel production in integrated algal-based wastewater treatment systems.

Keywords

Microalgae Wastewater treatment Nutrient removal Biomass valorisation

URI

http://hdl.handle.net/10400.9/6155

Citation

Pereira, A., Silva, T., Magalhães, I., Santos, W., Oliveira, M., Reis, A., Couto, E. & Calijuri, M.L. (2025). Pilot-Scale cultivation of microalgae in blended effluents: C/N ratio management to boost biomass and biofuel precursors. In: Journal of Environmental Chemical Engineering, 2025, vol. 13(6), article 119910. https://doi.org/10.1016/j.jece.2025.119910