The decolorization of azo dye Reactive Black 5 in a sequential anaerobic-aerobic system [Ardışık anaerobik - Aerobik sistemde Reaktif Siyah 5 azo boyasının renk giderimi]

The potential of the sequential anaerobic-aerobic system for decolorization of azo dye Reactive Black 5 (RB 5) was investigated in this study. The synthetic wastewater contained 150 mg/L dye and 3000 mg/L glucose- COD. An upflow anaerobic sludge blanket (UASB) reactor and continuously stirred aerobic reactors (CSAR) were used to the remove color and COD. The methane gas production efficiencies were also investigated under the anaerobic conditions. The UASB - CSAR were operated at different organic loading rates (OLR= 2.4-22.5 kg COD/m3.day) and hydraulic retention times (HRT= 3.2-30.1 h). The COD removal efficiencies decreased from 61 to 36.7% with increases in organic loadings from 2.4 to 22.5 kg COD/m3.day in the anaerobic UASB reactor. The color removals decrease from 99.8 to 90.7% when the HRT decreased from 30.1 to 3.2 hours. The methane production efficiencies obtained were 75 and 38.3% at the organic loading rates of 2.4 and 22.5 kg COD/m3.day respectively, in the anaerobic reactor. The effects of both sludge retention times (SRT) and the food to mass (F/M) ratio on the COD removal efficiencies was investigated in the aerobic reactor. COD removal efficiencies of 62.2 and 86.3% were obtained at 2 and 19 days SRT in the aerobic reactor. The COD removal efficiencies were found to be 86.3 and 62.2% at F/M ratios of 0.112 and 1.569 kgCOD/kgMLSS.day. The color and COD removal efficiencies obtained were 99.8% and 95% by using 150 mg/L of RB 5 dye concentration in the sequential anaerobic-aerobic reactor.