A successful strategy for start‐upof a laboratory‐scale UASB reactor treating sulfate‐rich sugar cane vinasse

BACKGROUND The aim of the present research was to provide a strategy for the start‐up of upflow anaerobic sludge blanket (UASB) reactors treating sugar cane vinasse, with emphasis on the relevant sulfur compounds along the reactor height. To this end, a laboratory‐scale UASB reactor was started up and its performance under the applied conditions was studied. RESULTS Biomass was able to assimilate organic loading rates from 3 to 10 kg chemical oxygen demand (COD) m R −3 d −1 , reducing VFAs accumulation, while increasing biogas production rate (BPR) from 0.92 to 4.12 m 3 m R −3 d −1 . The COD and sulfate (SO 4 2− ) were mainly removed in the reactor bed, showing homogenous distribution in the blanket and settler zones. However, from bottom to top of the reactor, a slight decrease of total and free sulfide concentrations was observed, indicating that the sludge bed in the UASB reactor was exposed to H 2 S concentrations higher than those measured in the reactor effluent. CONCLUSIONS During 54 days, the development of macroscopic granules, the COD removal efficiency, the BPR and the CH 4 content proved good indicators to monitor the start‐up period. Further research will be needed for strategy validation in pilot and full‐scale UASB reactors treating vinasse. © 2019 Society of Chemical Industry