Keywords: 
• hydrolysis-acidification /
• AMBBR /
• combined process /
• start-up

Abstract: A new combined nitrogen removal process ——hydrolysis acidification-AMBBR-aerobic process was proposed to optimize the presented wastewater treatment process，and the start-up of the combined reactor was researched. Domestication by signal reactor was adopted，three reactors of hydrolysisacidification reactor，AMBBR and oxidation reactor were setup at the same time，and the emphasis was on the first two reactors. Results show that，the hydrolysis-acidification reactor was started within 15 days by adding digested dry sludge，and increasing the flow slowly from small amount influent,at the end of the 15 days，the effluent of the hydrolysis-acidification reactor is very clear. The AMBBR is better to started-up by aerobic means and operated under anoxic condition. In this way，the time for biofilm culture is short and the renewal process is very fast. After the combined process was operated, the COD and ammonia removal efficiency reached 80% and 70% in a very short time, respectively. The biofilm renewed in 3 to 4 days after the nitrification effuent and the residual sludge were recycled,and the average total nitrogen in the effluent was below 20 mg/L. There was no sludge discharged from the combined process during the operation in three weeks.