Cultivation of Chlorella mutant in cellulosic ethanol wastewater using a static mixing airlift photo‐bioreactor for simultaneous wastewater treatment

Abstract

Cellulosic ethanol wastewater (CEW) is a mixture of wastewater from different procedures of cellulosic ethanol production. It cannot be completely purified with a secondary treatment method, such as anaerobic digestion. Microalgae cultivation is an effective way that can achieve advanced wastewater remediation and biomass production simultaneously. In this study, a static mixing airlift photo‐bioreactor (PBR) was designed for the cultivation of a Chlorella vulgaris mutant (named as Chlorella vulgaris CEW‐1) that was induced by ultraviolet (UV) mutagenesis. The microalgae exhibited sufficient robustness to undiluted CEW and its growth process in CEW under different conditions was investigated. The maximum biomass productivity in the static mixing airlift PBR can reach up to 1.98 g/L. The chemical oxygen demands removal rate (CODrr), total ammonia nitrogen removal rate (TANrr) and total phosphorus removal rate (TPrr) of the CEW were 54.8%, 97.6%, and 84.2%, respectively. Moreover, the kinetics of cell growth and substrate consumption of CEW were developed with logistic and modified Luedeking–Piret models. The superior efficiency of the static mixing PBR in microalgae cultivation and CEW treatment was further validated and compared with the other two PBRs. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1274–1281, 2017