Influence of the wavelength photoperiods and N/P ratio on wastewater treatment with microalgae-bacteria

This research investigates the effect of mixing wavelength light photoperiods (12 h blue, 8 h blue: 4 h green, 4 h blue: 8 h green, and 12 h green) and N/P ratios (1.3 to 8.3) on the growth microalgae-bacteria systems, organic matter, and nutrients removals. The highest microalgae-bacteria growth performance (mu = 0.2 d(-1), 481.1 perpendicular to 15.3 mg DW L-1) was observed when 8 h blue: 4 h green mixed wavelength and the low N/P ratio were used. For both N/P ratios, the biomass productivity was favored when using the blue light dominated in time. Mechanisms of nitrogen removal by assimilation depend on the N/P ratio, achieving assimilation between 49 and 65% at a low N/P ratio. High nitrogen removals (>50%) showed a strong relation with alkalinity culture conditions (pH. 8.5). The mixing of wavelength photoperiods seems to be a promissory strategy to achieved high biomass productivity and nutrients removal. However, for the optimal conditions, the N/P ratios in the wastewater should be considered.