GAC-amended UASB reactor for the stable treatment of toxic textile wastewater

A feasibility study was carried out in the laboratory for the sequential an aerobic/aerobic treatment of textile wastewater. The process units consiste d 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 conventio nal UASB reactor. The raw textile wastewater first passed through the GAC b ed and then through the sludge bed. By means of the GAC bed, the top-layer granular sludge was protected from toxicants. Biological regeneration of GA G, which was enhanced via a recycle flow, was demonstrated. The combined GA C-UASB and SCAS treatments allowed a stable performance and a COD (chemical oxygen demand) and colour removal of 98 and 95%, respectively.