چکیده (انگلیسی):

The main objective of this study was to evaluate the anaerobic conversion of vinasse intobiomethane with gradual increase in organic loading rate (OLR) in two upflow anaerobicsludge blanket (UASB) reactors, R1 and R2, with volumes of 40.5 and 21.5 L in the mesophilictemperature range. The UASB reactors were operated for 230 days with a hydraulic detec-tion time (HDT) of 2.8 d (R1) and 2.8–1.8 d (R2). The OLR values applied in the reactors were0.2–7.5 gtotalCOD (L d)−1in R1 and 0.2–11.5 gtotalCOD (L d)−1in R2. The average total chemicaloxygen demand (totalCOD) removal efficiencies ranged from 49% to 82% and the average con-version efficiencies of the removedtotalCOD into methane were 48–58% in R1 and 39–65%in R2. The effluent recirculation was used for an OLR above 6 gtotalCOD (L d)−1in R1 and8 gtotalCOD (L d)−1in R2 and was able to maintain the pH of the influent in R1 and R2 in therange from 6.5 to 6.8. However, this caused a decrease for 53–39% in the conversion efficiencyof the removedtotalCOD into methane in R2 because of the increase in the recalcitrant CODin the influent. The largest methane yield values were 0.181 and 0.185 (L) CH4(gtotalCODremoved)−1in R1 and R2, respectively. These values were attained after 140 days of opera-tion with an OLR of 5.0–7.5 gtotalCOD (L d)−1andtotalCOD removal efficiencies around 70 and80%.© 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. This isan open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).