This work studied alternative treatment schemes for the vinasse wastewater from wine distilleries aiming at overcoming the problems caused by the high nitrogen and sulfur concentrations. A plexiglas laboratory-scale upflow anaerobic sludge blanket (UASB) reactor of 20 L volume that was operated at 45°C and hydraulic retention time 1 d, was included in all the examined systems. System 1 was the conventional UASB reactor, system 2 was the UASB reactor supplemented with iron. System 3 consisted of the UASB reactor supplemented with iron and a CSTR reactor that operated under the following conditions: Diluted Oxygen 1.2 mg/L, Hydraulic Retention Time 1 d, pH 6.7 and Temperature 45°C. System 3 aimed at converting ammonium directly to dinitrogen gas under anaerobic conditions but it needed to be preceeded by a first partial nitrification step. All systems had high COD efficiencies over 75%. Ferrous iron addition apart from enhancing the performance of systems 2 and 3, it was able to retain all sulphur content of the wastewater as ferrous sulfide stripping the biogas from hydrogen sulfide. System 3 also managed to meet its goal, since it achieved an 86% nitrogen reduction. Conclusively, system 3 seems to be a very promising environmental technology for the treatment of distillery and winery byproducts, as well as industrial wastewater with high sulfur and nitrogen content.
Keywords: anammox, ferrous iron, nitrogen reduction, UASB, vinasse