Recycling sewage sludge from wastewater treatment plants is one of the most challenging environmental problems. In this work, we develop a one-step facile synthesis method of converting iron-rich sewage sludge into granular sludge carbon (GSC), further applying as particle electrodes in three-dimensional electrochemical reactor (3DER) for wastewater treatment. Iron in sludge and zinc in activator are insitu loaded on particle electrodes as catalytic ingredients. The prepared GSC under different pyrolysis temperature are characterized to investigate the physical, chemical and electrochemical properties. The treatment performances of GSC as particle electrodes are evaluated by degrading bisphenol A (BPA) and Rhodamine B (RhB) in a continuous-flow 3DER. The stability of the GSC are evaluated and possible reaction mechanism are explored. Results indicate that GSC fabricated are typical macroporous material, exhibiting good electrocatalytic activity. The 500 degrees C/GSC packed 3DER shows the best performances in contaminants removal, that was attributed to larger specific surface and superior electrochemical properties with cooperation of iron oxide and zinc oxide components. The 500 degrees C/GSC prepared are proved to be suitable for utilizing as particle electrodes in 3DER. Our work offers a new strategy for sewage sludge reuse and provides a promising future for 3DER applications. (C) 2018 Elsevier Ltd. All rights reserved.