Facilities aerobic - anoxic alternate operating environment to achieve nitrification and denitrification - alternating operation to achieve the effect of nitrogen and phosphorus removal, sewage treatment Changde here by setting the subsequent aerobic pool acid hydrolysis process water back to hydrolysis acidification tank to achieve. Slaughter sewage organic matter content, good biodegradability which high concentrations of easily degradable organic matter, process more difficult, slaughter wastewater nutrients mainly nitrogen and phosphorus.