The pilot scale electron beam flue gas treatment (EBFGT) plant was constructed at Saudi Aramco's Refinery in Jiddah, Saudi Arabia. The plant was designed,to treat 2000 Nm(3)/h of flue gas emitted from a heavy fuel oil fired boiler. A unique mobile electron accelerator unit (600 key, 20 kW) made by EB TECH Co., Ltd., Korea was used as a beam source. The pilot plant operation proved the high potential of the technology for simultaneous control of sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions. The obtained removal efficiencies reached 98.5% for SO2 and 83.1% for NOx. Two types of byproduct collection devices - cartridge bag filter and electrostatic precipitator - were tested. The obtained byproduct was a high quality fertilizer that can be used directly or as a substrate for NPK blends manufacturing. The soluble part of the byproduct was almost pure ammonium sulfate (98% to 99%) with some amount of ammonium nitrate. The content of heavy metals in the byproduct was very low and lower than the allowed standards by two orders of magnitude. The results of the research are the basis for the design of a full industrial scale EBFGT plant for treatment of flue gas from heavy fuel oil combustion. (C) 2016 Elsevier B.V. All rights reserved.