Anaerobic treatment of sugar cane vinasse: treatability and real‐scale operation
2018
López, Iván | Borzacconi, Liliana | Passeggi, Mauricio
BACKGROUND: Vinasse is a wastewater from bioethanol production with a very high concentration of organic matter, usually from 40 to 80 gCOD L‐¹. These features make this wastewater attractive for treatment in an anaerobic system. Anaerobic processes allow the valorisation of this highly polluting wastewater as an energy resource in an environmentally friendly way. RESULTS: A multiscale approach was followed, using batch tests, continuous bench scale reactors, and a full‐scale upflow anaerobic sludge bed (UASB) reactor. Potential inhibition due to high potassium concentrations was evaluated. Using batch tests, the IC50 potassium concentration was determined to be around 6 g L‐¹, but continuous reactors could adapt the biomass to this concentration level without removal efficiency decay. A load of 20 gCOD L‐¹ d with chemical oxygen demand (COD) removal efficiencies between 60% and 80% were reached in bench scale UASB and expanded granular sludge bed (EGSB) reactors. Finally, a 100 m³ UASB reactor located in a distillery was tested under industrial conditions. A load of 0.6 kgCOD kg‐¹VSS d‐¹ was achieved with a COD removal efficiency of 78%. CONCLUSION: Although potassium was inhibitory for the inoculum, the sludge from a continuously operated reactor can be adapted to high potassium concentrations without affecting its performance. The real possibility of working with undiluted vinasse was also verified. For distilleries like the Uruguayan case, which produces 18 000 m³ of bioethanol per year, 5x10 m³ of biogas per year, with 68% methane, could be expected, representing an energy potential of about one‐third of the main fuel produced. © 2017 Society of Chemical Industry
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