CONICET | Buscador de Institutos y Recursos Humanos

Certain wastewaters from the non-alcoholic sugar-sweetened beverage industry, particularly those discarded due to deficient bottling processes or those returned from the market due to quality policies, exhibit chemical oxygen demand (COD) levels as high as 150,000 mg O2/L. Thus, treating them prior to discharging them into the environment involves high investment and operating costs. Most of the COD of these drinks is due to their sugar content: 60 ?150 g/L, depending on the beverage. Therefore, any treatment process capable of transforming the sugars into other compounds that are easy to remove, such as ethanol or CO2, should be regarded as an interesting alternative. In this work, several high-strength wastewaters from the non-alcoholic sugar-sweetened beverage industry(flavor-enhanced waters, fruit juices, sports and energy drinks and soft drinks) were assayed as media for yeast-mediated fermentation to produce ethanol and CO2, which can be easily removed. The addition of simple nutrients to media inoculated with 5 g/L of yeast, along with pH adjustment, made it possible to deplete the COD by 85% in less than 12 hours, with mean specific COD removal rates between1.03 and 1.40 mgbiomass-1 h-1, which are far above the rates achieved by conventional treatment processes. The residual COD, once ethanol and biomass are removed from the media after completion of the fermentation process, was mainly due to glycerol. The feasibility of removing the glycerol by aerobic propagation of yeast is also studied in this work. Besides being faster than conventional treatment processes, the proposed process allows to produce added-value products: approximately 0.40 g of ethanol and 0.44g of CO2 per g of removed COD.