Biobutanol and carotenoid production from Hindakia tetrachotoma grown in microplastic-contaminated wastewater within a biorefinery concept

Abstract

Microalgae can produce pigments and biofuels together within the biorefinery concept. The aim of this study was to produce carotenoids and biobutanol from H. tetrachotoma grown in wastewater contaminated with microplastics such as polypropylene (PP) and polyethylene (PE). In this study, H. tetrachotoma was grown under blue, white and red light to determine the maximum biomass and carbohydrate productivities and in various amounts of PP and PE (25, 75, and 150 mg/L) along with two mixtures of microalgae (25, 75, and 150 mg/L PP+PE) to examine how they affect carotenoids and biobutanol. The highest biobutanol productivity and carotenoid content were 0.040 ± 0.001 g/g biomass and 4.6 ± 0.1 mg/g biomass at 75 mg/L of PP+PE, respectively. This resulted in an increase of approximately 66 % for biobutanol. Also, to show the stress effects of microplastics on microalgae, CAT, SOD, MDA and APX activities were examined and the highest CAT, SOD, APX enzyme activities were 87 ± 3 U/mg protein, 108 ± 4 U/mg protein and 14.2 ± 0.3 U/mg protein at 75 mg/L of PP+PE, respectively. In conclusion, H. tetrachotoma can be used for both carotenoid and biobutanol production in the light of the biorefinery concept in wastewater contaminated with microplastics.