This study assessed the effect that working conditions have on biomass production, nutrient recovery, and microbial diversity in a wastewater treatment process using 100 m 2 outdoor raceway reactors. The influence of the culture depth (0.10–0.20 m) and dilution rate (0.05–0.30 day −1 ) was assessed using the response surface methodology. The results showed that both parameters significantly affected biomass productivity and nutrient removal efficiency, with maximum productivity (17.68 g·m −2 ·day −1 ) being achieved at a 0.15 m depth and a 0.30 day −1 dilution rate. The maximum nitrogen and phosphorus removal rates were 8.57 and 0.51 g·m −2 ·day −1 , respectively. Metagenomic analyses revealed that bacterial populations dominated the consortia (66–85%), while higher dilution rates decreased microalgal abundance and promoted denitrifying genera such as Thauera . Empirical models accurately predicted macromolecular composition (R 2 > 0.87), confirming that operational conditions strongly influence the protein, lipid, and ash contents. Furthermore, near-infrared spectroscopy combined with partial least squares regression successfully predicted protein (R 2 = 0.95, RPD = 4.48) and ash (R 2 = 0.95, RPD = 4.74) contents, demonstrating its suitability as a rapid alternative to conventional analyses. Overall, this work highlights the feasibility of coupling microalgae-based wastewater treatment with rapid biomass characterisation techniques to optimise both environmental and bioproduct outcomes. • Maximum biomass productivity achieved 17.7 g·m −2 ·day −1 at 0.15 m and 0.30 day −1 • High dilution rates enriched the bacterial genus Thauera within the consortium • Empirical models accurately predicted protein, lipid, and ash composition (R 2 > 0.83) • Protein accumulation was favoured at higher dilution rates and moderate depths • Near-infrased spectroscopy succesfully predicted protein (R 2 = 0.95) and ash contents
Viviano et al. (Thu,) studied this question.