High-nitrate wastewater treatment in an expanded granular sludge bed reactor and microbial diversity using 454 pyrosequencing analysis

► Complete denitrification can be achieved with nitrate nitrogen concentration as high as 14000 mg/L. ► The optimal performance parameters were achieved: C/N ratio for 2, Vup for 3.0, pH of 6.2-8.2. ► 454-Pyrosequencing technology was used to analyze bacterial diversity. ► The EGSB bioreactor offers bright prospects for the treatment of high strength nitrate wastewater.