Effects of leachate concentration, carbon dioxide and aeration flow rate on chlorophyll and carotenoid productivity and bioremediation potential of the microalga <i>Chlorella minutissima</i>

Abstract

The use of microalgae cultures to process effluents from industries, leachates, and tanneries, among others, quantified by the reduction  of metallic materials in the medium and the reduction of chemical oxygen demand (COD), helps reduce the environmental impact caused  by human development. In addition, with the growth of the culture, it is possible to produce a significant amount of chlorophyll, a  carotenoid of high value in the cosmetics and food industries that are used as a natural pigment. In this context, this work presents a study conducted to verify the bioremediation and chlorophyll production potential of the cultivation of the microalgae Chlorella  minutíssima, using the Taguchi method. The microalgae Chlorella minutissima has given good results in the bioremediation of leachate,  as a mean reduction of 33% in COD was obtained, as well as a 92% reduction in the toxic components. In addition, statistical analysis  revealed that the four process factors were significant factors for chlorophyll a, chlorophyll b and carotenoid productivity (p < 0.05).  Finally, it was observed that the maximum chlorophyll a (111.9 ± 0.8 mg·L−1·d−1), chlorophyll b (66.1 ± 1.7 mg·L−1·d−1), and carotenoid  (31.9 ± 0.03 mg·L−1·d−1) values obtained occurred in Experiment 8, which is closer to the ideal conditions identified by statistical analysis,  revealing the effectiveness of the use of the Taguchi method for the design of experiments.