The string speed was 450 rpm and the air flowrate maintained at
5 L/min.Each chamber was considered asacontinuous stirred-
tank reactor owing to the completely mixing conditions.Cations
including ammonium in swine wastewater were ion-exchanged
between chambers A and Bvia aCEM.The ion-exch anged ammonium
was nitrifiedtonitrate inchamber B.The ammonium trans-
portation between chambers Aand Bvia aCEM was determined by
the ammonium flux,and the nitrate transportation was caused by
the concentratio n gradient between chambers Band Cvia anAEM
(Park et al.,2009b,2011 ). The inoculated activated sludge for
chamber B was taken from alivestock wastewater treatment plant
(WWTP) located atGongju,Korea.Activated sludge was washed
three times with purifiedwater.The washed activated sludge with
50 mMphosphat e buffer solution was inoculated tochamber B.
The average concentratio n ofinoculated activated sludge incham-
ber Bwas 3040 ±20mg/L.The pHofchamber Bwas adjusted to
between 7.0 and 7.5 using 1.0 NNaOH or1.0 NH2SO4. Monovalent
anions such as nitrite and nitrate inchamber Bwere ion-ex-
changed between chambers B and Cvia anAEM due tothe concen-
tration gradient. NaHCO 3 was added tostudy nitrification(2.0g/L).
In addition,the concentr ation of dissolved oxygen (DO)was mon-
itored. Organic matter (electrondonor)inswine wastewater flo-
wed into chamber Cand was used for denitrification