This study was implemented during 210 days. The nitrogen treatment efficiency of the system was evaluated with different hydraulic retention times (HRTs). The short HRT of hours in the AX reactor affected to the total nitrogen treatment efficiency is low of ± . With the hydraulic retention times in PN + AX reactors of 9 and 6 hours, the effluent quality met the requirements of B-column according to QCVN 14:2008/BTNMT or QCVN 40:2011/BTNMT. |