Coupled Inverse Fluidized Bed Bioreactor with Advanced Oxidation Processes for Treatment of Vinasse

Vinasse is the wastewater generated from ethanol distillation; it is characterized by high levels of organic and inorganic matter, high exit temperature, dissolved salts and low pH. In this work the treatment of undiluted vinasse was achieved using sequentially-coupled biological and advanced oxidation processes. The initial characterization of vinasse showed a high Chemical Oxygen Demand (COD, 32 kg m -3 ), high Total Organic Carbon (TOC, 24.5 kg m -3 ) and low pH (2.5). The first stage of the biological treatment of the vinasse was carried out in an inverse fluidized bed bioreactor with a microbial consortium using polypropylene as support material. The fluidized bed bioreactor was kept at a constant temperature (37 ± 1oC) and pH (6.0 ± 0.5) for 90 days. After the biological process, the vinasse was continuously fed to the photoreactor using a peristaltic pump 2.8 × 10 -3 kg of FeSO 4 •7H 2 O were added to the vinasse and allowed to dissolve in the dark for five minutes; after this time, 15.3 m 3 of hydrogen peroxide (H 2 O 2 ) (30% w/w) were added, and subsequently, the UV radiation was allowed to reach the photoreactor to treat the effluent for 3600 s at pH = 3. Results showed that the maximum organic matter removed using the biological process, measured as COD, was 80% after 90 days. Additionally, 88% of COD removal was achieved using the photo-assisted Fenton oxidation. The overall COD removal after the sequentially-coupled processes reached a value as low as 0.194 kg m -3 , achieving over 99% of COD removal as well as complete TOC removal.