Avaliação da eficiência de Desmodesmus subspicatus (R. Chodat) E. Hegewald & A. Schmidt (Chlorophyceae) cultivada em fotobiorreator tubular com efluente da ETE-UNISC, visando biorremediação e obtenção de energia.

Abstract

The high biodiversity of microalgae combined with genetic improvement and establishment of culture technology on a large scale, are allowing them to be used in various applications, particularly the treatment of wastewater from industrial processes, mitigation of greenhouse gases by the assimilation of carbon dioxide (CO2) and the production of biofuels such as biodiesel and ethanol. In this context, this work aimed at the design, construction and operation of a tubular bubble column photo bioreactor with continuous flow of gases and semi artificial lighting, in the University of Santa Cruz do Sul (UNISC), using as test organism the microalgae Desmodesmus subspicatus (R.Chodat) E. Hegewald & A. Schmidt (CHLOROPHYTA), cultivated in the effluent from the UNISC Sewage Treatment Plant (STP-UNISC), assessing the growing capacity, nutrient removal and the biomass oleaginous potential in order to be used in the future for biodiesel production. For cultivation of D. subspicatus without carbon dioxide contribution, the maximum cell density obtained was 8, 49 x 106 cells mL-1, reached at the third day of cultivation. As for the culture with supplemental CO2, the maximum cell density obtained was 25.98 x 106 cells mL-1, reached at the seventh day of cultivation. For the dry weight of biomass, the culture without CO2 contribution in the effluent reached a maximum of 185.0 mg L-1, and the culture with CO2 contribution reached a maximum of 2435.3 mg L-1. The results indicate that there was assimilation of nutrients (biomass growth) mainly in the culture with additional carbon dioxide. The quality of the effluent and the presence of carbon dioxide did not provide additional distinct fatty acid profiles, highlighting the fatty acids C16: 0 (palmitic acid) and C18: 1 (oleic acid). The extracted oil content averaged 18 and 12% for the culture with and without CO2, respectively.