High removal of chemical and biochemical oxygen demand from tequila vinasses by using physicochemical and biological methods

Abstract

The goal of this research is to find a more effective treatment for tequila vinasses (TVs) with potential industrial application in order to comply with the Mexican environmental regulations. TVs are characterized by their high content of solids, high values of biochemical oxygen demand (BOD ₅), chemical oxygen demand (COD), low pH and intense colour; thus, disposal of untreated TVs severely impacts the environment. Physicochemical and biological treatments, and a combination of both, were probed on the remediation of TVs. The use of alginate for the physicochemical treatment of TVs reduced BOD ₅ and COD values by 70.6% and 14.2%, respectively. Twenty white-rot fungi (WRF) strains were tested in TV-based solid media. Pleurotus ostreatus 7992 and Trametes trogii 8154 were selected due to their ability to grow on TV-based solid media. Ligninolytic enzymes’ production was observed in liquid cultures of both fungi. Using the selected WRF for TVs’ bioremediation, both COD and BOD ₅ were reduced by 88.7% and 89.7%, respectively. Applying sequential physicochemical and biological treatments, BOD ₅ and COD were reduced by 91.6% and 93.1%, respectively. Results showed that alginate and selected WRF have potential for the industrial treatment of TVs.

Keywords:

• alginate
• Pleurotus ostreatus
• Trametes trogii
• vinasses
• bioremediation

Acknowledgements

We are grateful to Dr Mark D. Redwood for the proof-reading and the valuable comments that helped us to improve the manuscript.

Funding

The authors acknowledge the financial support of Consejo Nacional de Ciencia y Tecnología (CONACYT), México; and for the grant No. 98369 conceded to J. L. Retes-Pruneda.