Real textile industrial wastewater treatment and biodiesel production using microalgae

Abstract

Microalgae are promising feedstocks capable to simultaneously treat wastewater and produce biodiesel. The focus current studyis the treatment of real textile wastewater (RTWW) and successive biodiesel production using microalgae (Chlorella vulgaris). Cultivation was carried out in unsterilized 100% (without dilution) and diluted (25%, 50%, 75%) RTWW. Microalgae cultivation in defined media (BG-11) was set as a control. In results, 50% dilution showed the highest decolorization efficiency (99 ± 0.13%), COD removal (82%), and Fatty Acid Methyl Esters (FAMEs) content (32.62 mg g−1 of biomass). Cultivation was carried out in mixotrophic and heterotrophic conditions to improve microalgae performance. Mixotrophic cultivation showed 99 ± 0.29% decolorization, 94% COD removal, and 61.65 mg g−1 of biomass as FAMEs, which was higher (p < 0.05) than the heterotrophic condition. FAME content and COD removal in mixotrophic conditions were higher (p < 0.05) than in photo-autotrophic conditions; however, there was no significant difference (p > 0.05) in the decolorization efficiency. Thus, it turned out that 50% diluted RTWW under mixotrophic conditions was the most suitable choice to achieve high treatment performance and the FAMEs yield. This study demonstrates that RTWW could be used as a microalgae feedstock without sterilization and less freshwater addition (50% of RTWW). Thus, it can be considered a promising feedstock for economical biodiesel production.