Study on Anaerobic Simultaneous Denitrification and Methanogenesis Combined with Shortcut Nitrification Process Treating Piggery Wastewater

Abstract

An expanded granular sludge bed (EGSB) was combined with an anaerobic/anoxic/oxic process (A2/O) to treat piggery wastewater, in which the EGSB was used as a simultaneous methanogenesis and denitrification reactor and the A2/O as an shortcut nitrification reactor. The results showed that: 1) The COD of effluent in anaerobic reactor increased in earlier stage and decreased in later stage with increasing reflux ratios each time, and reached to about 550 mg/L finally. The COD removal efficiencies of the whole process were about 150 mg/L, and almost not affected by different reflux ratios. 2) Simultaneous denitrification and methanogenesis realized successfully after the aerobic effluent recirculated to the anaerobic reactor. The highest nitrite loading reached 1.48 kg/m3.d with constant increase of reflux ratio, while nitrite removal efficiencies were always 100%. 3) Short-cut nitrification was perfored steadily in the whole combined system. When reflux ratios were 50%, 100%, 200%, 300%, respectively, ammonia nitrogen removal efficiencies were all 100%, and total nitrogen removal efficiencies were 52.3%, 53.1%, 68.7%,85.1%, respectively. 4) The first reaction was denitrification when nitrite was recycled to anaerobic reactor, so methane contents were very little in earlier stage with increasing reflux ratios every time, but increased gradually after a period of operation.