Resumen
Taguchi statistical design, an orthogonal array (OA) method, was used to study the impact of the COD/SO42- ratio, hydraulic retention time (HRT) and linoleic acid (LA) concentration on sulfate (SO42-) reduction in an anaerobic sequencing batch reactor using glucose as the electron donor. Based on the OA, optimum condition for maximum SO42- reduction was evaluated. Increasing the COD/SO42- ratio and HRT caused decreasing SO42- reduction while increased SO42- reduction was observed with increasing LA concentration (1 g L-1). In control (not fed LA) cultures, higher SO42- reduction (87% ± 3%) was observed at a low COD/SO42- ratio of 0.8. This indicates that increasing SO42- reduction was observed at increasing SO42- loading rates. In general, results from this study reveal that limiting the substrate concentration with high SO42- levels (low COD/SO42- ratio) favors high SO42-removal. Surface plots were used to evaluate the significant interactions between the experimental factors. Accuracy of the model was verified using an analysis of residuals. Optimum conditions for maximum SO42- reduction (97.61%) were observed at a COD/SO42- ratio of 0.8 (level 1), 12 h HRT (level 1) together with 1000 mg L-1 LA addition (level 3). In general, the Taguchi OA provided a useful approach for predicting the percent SO42- reduction in inhibited mixed anaerobic cultures within the factor levels investigated.