Evaluation of molasses concentration and anoxic-aerobic react period in biodecolorization and mineralization of tartrazine (acid yellow 23)

Dyes are widely used in the textile industry and 10–15% of these dyes are lost to effluent during the dyeing process. Dye reduction usually requires anaerobic or anoxic conditions, whereas bacterial biodegradation of aromatic amines is an exclusively aerobic process. Despite of its feasibility, increase efficiency of anaerobic color removal requires fast reductive processes with electron donor (organic co-substrate) which is usually the drawbacks of conventional biological process. The present study focuses on the evaluation of molasses concentration and anoxicaerobic react period in biodecolorization and mineralization of tartrazine under integrated anoxic-aerobic react sequencing batch reactor (IAASBR). The IAASBR system was operated under anoxic-aerobic condition with 24 hours per cycle. Different molasses loading (0.5 g/L; 1.0 g/L) and anoxic/aerobic react periods (17/4 hours; 12.5/8.5 hours) were adopted, and their effects on microorganism growth, tartrazine decolorization and COD removal were determined. Removal efficiency of tartrazine dye and COD increased to around 50–70% and up to 95%, respectively, after the molasses concentration doubled from 0.5 g/L to 1.0 g/L. The MLVSS also increased from 3660 mg/L to 7700 mg/L. The presence of molasses promote the growth of biomass in the IAASBR system and improve the treatment efficiency of IAASBR in biodecolorization and mineralization of tartrazine. In addition, shorter anoxic react (12.5/8.5 hours anoxic/aerobic) exhibited higher COD reduction (up to 94.00 mg COD/L.hr) compared to 71.93 mg COD/L.hr for 17/4 hours anoxic/aerobic period. However, for biodecolorization of tartrazine dye, influence of the anoxic-aerobic react duration was insignificant but more consistent tartrazine removal was observed under 12.5/8.5 hours anoxic/aerobic period.