TREATMENT OF VINASSES IN AN ANAEROBIC INVERSE FLUIDIZED BED REACTOR

The vinasses are the residual liquid waste after distillation of the ethanol. This distillery effluent generally has a very high chemical oxygen demand (COD) concentration and low pH. Anaerobic treatment whit biofilms systems is a well-established technology for the treatment of industrial effluents. The anaerobic inverse fluidized bed reactor (IFBR) has been developed to provide biological treatment of high strength organic wastewater for their large specific surface and their low energy requirements for fluidization. This study describes the performance of IFBR with Extendospher (R), for the treatment of vinasses. The start-up was in batch, increasing gradually the organic load rate (OLR): 0.5, 1.0, 3.3, 6.8 and 10.4 gCOD/L d. Different hydraulic retention times (HRT) were evaluated: 10, 5 and 1 days. During the batch operation, the COD removal obtained was of 81 %, and for OLR of 0.5, 1.0, 3.3, 6.8 gCOD/L d the removal obtained was 58, 67, 59 and 50 % respectively. For a maximum OLR of 10.4 gCOD/L d, the COD removal was 38 %, and the system presented instability and a decrease of yield methane. The methane production initiated after 110 days from the start-up of the IFBR, to organic load rate of 1.0 gCOD/L d. The system reached values in the methane yield from 0.15 up to 0.34 LCH4/g CODremoved, for the different organic load rates. During the operation to a constant OLR of 6.4 gCOD/L d, and a HRT of 1 day, the IFBR reached a maximum efficiency of removal of 52 %.