GAC-Amended UASB Reactor for the Stable Treatment of Toxic Textile Wastewater

Abstract

A feasibility study was carried out in the laboratory for the sequential anaerobic/aerobic treatment of textile wastewater. The process units consisted of an anaerobic UASB (upflow anaerobic sludge blanket) reactor and a SCAS (semi-continuous activated sludge) reactor. A contact-sorption layer with GAC (granular activated carbon) was provided at the bottom of the conventional UASB reactor. The raw textile wastewater first passed through the GAC bed and then through the sludge bed. By means of the GAC bed, the top-layer granular sludge was protected from toxicants. Biological regeneration of GAC, which was enhanced via a recycle flow, was demonstrated. The combined GAC-UASB and SCAS treatments allowed a stable performance and a COD (chemical oxygen demand) and colour removal of 98 and 95 %, respectively.

Keywords:

• Activated sludge
• colour removal
• granular activated carbon
• textile wastewater
• toxic wastewater
• UASB reactor