The UASB treatment of winery wastewater under submesophilic and psychrophilic conditions

The start-up and operational performance of two laboratory UASB reactors (working volume of 2.6 1) treating diluted vinasse (1-17 g COD 1(-1)) were investigated at 35 degrees C (run 1, without recycle), 19-21 degrees C (run 2, without recycle), 18-20 degrees C (run 3, with recycle 1:1) and 9-10 degrees C (run 4, with recycle 1:2.6). The reactors for runs 1 and 2 were seeded with flocculant mesophilic sludge. For runs 3 and 4, the reactor seed sludge was upgraded by addition of 30% of psychrotrophically adapted granular sludge. A successful start-up of the reactors for all runs was achieved in 2-3 months. The maximum applied organic loading rates (OLR) were 15.9, 6.5, 12.5 and 7.2 g COD 1(-1)d(-1) for runs 1-4, respectively Hydraulic retention times at these loadings were around or less than 1 day. The total COD removals achieved under these OLR were highs than 85% for the first 3 runs and higher than 60% for run 4 with substantial decoloration of effluents (reduction of polyphenol content varied between 45-67%).