Study on the growth of a native microalgae-bacteria mixed culture from the Peruvian Andes exposed to different tannery effluent dilutions and photoperiod.

This study evaluated the suitability of wastewater treatment from tanneries located in the city of Arequipa, Peru. The growth of the microalgae-bacteria consortium enriched from wastewater ponds located in high altitude (2300 m above sea level) and areas with high ultraviolet radiation, was characterized under different wastewater dilutions, nutrient-corrected wastewater and various light periods in a laboratory-scale air-lift system over a 9-day cultivation period . The results indicate a higher COD removal at low dilutions (50%) in both 16L:8D and 24L:0D photoperiods, achieving 43.63% and 42.93%, respectively, however, a higher daily consumption rate was observed in treatments with 75% and 100% tannery wastewater, with the highest COD consumption recorded in the 100% treatment under the 16L:8D photoperiod, with at 85.50 mg L⁻¹ d⁻¹. Regarding nitrogen removal and consumption, significant results were obtained in the 100% treatment with 16L:8D photoperiod with values of 55.46% and 3.81 mg L^-1 d^-1 respectively, while for phosphorus all treatments had high removals (>95%). On the other hand, the highest productivity occurred in the 100% treatment for both the 16L:8D and 24;0 photoperiod with a value of 52.85 and 64.28 mg L^-1 d ^-1 respectively. Finally, by phosphorous supplementation in the medium, the productivity in all treatments improved, obtaining the maximum biomass productivity in the 75% 24L:0D treatment with 95,714 mg L^-1 d^-1. The maximum accumulation of lipids was 18.7% of the effluent with 100%, 16L:8D photoperiod. These results confirm that microalgae technology is an ecofriendly alternative to treat tannery beam house wastewaters.