Análisis de la eficiencia del tratamiento con microalgas Chlorella vulgaris y Nannochloropsis sp para la remoción de nutrientes y materia orgánica de aguas residuales domésticas provenientes de una vivienda de la parroquia Baños

Abstract

The contamination of water caused by untreated domestic wastewater leads to environmental issues, such as eutrophication. A laboratory-scale study was conducted to evaluate the removal capacity of nitrates, nitrites, ammonium, and phosphorus using the species Chlorella vulgaris and Nannochloropsis sp.. The tests were performed under the following light intensities: 480 μmol/m²s, 360 μmol/m²s, and 240 μmol/m²s. It was determined that there were no significant differences in removal rates influenced by light intensity. However, at 240 μmol/m²s over 200 minutes, the following growth rates were recorded: 4,44 day⁻¹ for Chlorella vulgaris and 2,17 day⁻¹ for Nannochloropsis sp.. The biomass concentration variation tests lasted 7 days, and specific growth rates were obtained during the exponential phase, with 0,2810 day⁻¹ for the lowest biomass concentration and 0,2194 day⁻¹ for the highest in Chlorella vulgaris. For Nannochloropsis sp., the rates were 0,1666 day⁻¹ and 0,1416 day⁻¹, respectively. The respective doubling times for the microalgae were 2,46, 3.15, 4.16, and 4,89 days. Additionally, the removal percentages for nitrites, nitrates, ammonium, and phosphorus reached values of 87,5%, 95,12%, 97,3%, and 78% for Chlorella vulgaris, and 85,7%, 95,12%, 35,39%, and 28,57% for Nannochloropsis sp.. The COD for both species exceeded 70%. The harvested microalgae after treatment showed a carbon-nitrogen ratio of 1,8:1 for Chlorella vulgaris and 1,2:1 for Nannochloropsis sp.