Alkaline textile wastewater biotreatment: A sulfate-reducing granular sludge based lab-scale study.

In this study the feasibility of treating dyeing wastewater with sulfate reducing granular sludge was explored, focusing on decolorization/degradation of azo dye (Procion Red HE-7B) and the performance of microbial consortia under alkaline conditions (pH=11). Efficiency of HE-7B degradation was influenced strongly by the chemical oxygen demand (COD) concentration which was examined in the range of 500-3000mg/L. COD removal efficiency was reduced at high COD concentration, while specific removal rate was enhanced to 17.5 mg-COD/gVSSh-1. HE-7B removal was also improved at higher organic strength with more than 90% removal efficiency and a first-rate removal constant of 5.57h-1 for dye degradation. Three dye-degradation metabolites were identified by HPLC-MS. The granular structure provided enhanced removal performance for HE-7B and COD in comparison to a near-identical floc SRB system and the key functional organisms were identified by high throughput sequencing. This study demonstrates an example of a niche application where SRB granules can be applied for high efficient and cost-effective treatment of a wastewater under adverse environmental conditions.