An ion exchange biological reactor (IEBR) treated organic matter and nitrogen in swine wastewater at 23 degrees C. The enhanced IEBR enhanced the ammonium flux by electrochemical attraction. The abiotic ammonium fluxes at the applied voltage of 0, 1, and 3 V were 1.33, 1.79, and 2.73 mg/m(2)/s, respectively. In the meantime, the ammonium fluxes caused by biological nitrification at the applied voltage of 0, 1, and 3 V were 1.54, 2.07, and 3.59 mg/m(2)/s, respectively. Removal of organic matter and nitrogen in swine wastewater was proportional to the applied voltage. The average SCUD removal efficiencies at the applied voltage of 0, 1, and 2 V were 59.7%, 60.2%, and 67.0%, respectively. The average total nitrogen removal efficiencies at the applied voltage of 0, 1, and 2 V were 39.8%, 49.5%, and 58.7%, respectively. (C) 2012 Elsevier Ltd. All rights reserved.