Research on the Tolerance and Degradation of o-Cresol by Microalgae

Abstract

o-Cresol shows high toxicity and stability. To explore a better degradation method of o-cresol, the degradation of o-cresol by three kinds of microalgae (Selenastrum capricornutum, Scenedesmus obliquus, and Microcystis aeruginosa) was researched in this paper. The growth status and degradation rate were used to reflect the tolerance and degradation effect of microalgae. The effects of the medium’s initial pH, microalgal density, and different exogenous pollutants on the degradation of o-cresol by Selenastrum capricornutum were investigated. The results showed that Selenastrum capricornutum had the best degradation effect on o-cresol. microalgal density increased after adaptation to different concentrations of o-cresol for some time. At pH 7.0 as the initial condition, the microalgal exhibited the best results of degradation. When the microalgal density OD680 was 0.20, o-cresol was the first to be completely degraded within 5 days. At higher initial concentrations of o-cresol, the microalgae preferentially degraded glucose to promote the growth of the microalgae under mixotrophic cultivation. Selenastrum capricornutum could degrade phenol and o-cresol at the same time, and the degradation was completed within 8 days when the initial concentration of o-cresol and phenol were 100 and 120 mg/L. It was proven that the degradation of o-cresol by Selenastrum capricornutum is feasible under suitable conditions.