Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment

The long-term performance of a bioaugmented membrane bioreactor (MBR) containing

a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally

different azo dyes was observed. A unique feeding strategy, consistent with the mode of

evolution of separate waste streams in textile plants, was adopted to make the best use of the

GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the

colorless media was simultaneously fed through the aerobic zone. Preliminary experiments

confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR

and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness

of the process under gradually increasing dye-loading was tested. The respective

average dye concentrations (mg/L) in the sample from GAC-zone and the membranepermeate

under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate

(0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were

3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during

a period of over 7 months under extremely high dye-loadings demonstrated the superiority

of the proposed hybrid process.