[Stability of the two-stage SBR system treating dyeing wastewater during a long-term operation].

The stability of the two-stage SBR system treating dyeing wastewater was investigated during a 120-cycle continuous operation. The system was fed with influent of low dye concentration and high dye concentration. The results showed that the two-stage SBR system was adaptable to the change of influent quality and operation conditions during the long-term operation. It could efficiently remove the pollutants in the wastewater, the average dyestuff and COD removal rates were 81% to 92.5% and 89.4% to 93.1% respectively for low and high influent loading, and could produce continuous good quality effluent. In the two-stage SBR system, the anaerobic sludge had the characteristics of high activity and strong pollutant degradation ability, and the aerobic sludge existed in the form of aggregate structure, which helped stabilize the effluent quality.