A NO(x) aftertreatment system, using nonthermal plasma (NTP) reduction and exhaust gas components' recirculation, is investigated. A pilot-scale system is applied to a stationary diesel engine. In this system, NO(x) is first removed by adsorption, and subsequently, the adsorbent is regenerated by thermal desorption. NO(x) desorbed is reduced by using nitrogen NTR Moreover, NO(x), CO(2), and water vapor recirculated into the engine intake reduce NO(x). In this study, approximately 57% of the NO(x) of the exhaust (NO(x): 240-325 ppm, flow rate = 300 NL/min) can be continuously treated for 58 h. A system energy efficiency of 120 g (NO(2))/kWh is obtained. (C) 2009 Elsevier B.V. All rights reserved.