Drinking water treatment residuals (WTRs) are safe byproducts of water treatment plants containing iron. This work studies the degradation of atrazine (ATZ) by WTR-catalyzed peroxymonosulfate (PMS) in aqueous solutions. Factors that affect the catalytic performance (the PMS concentration, catalyst dose, initial solution pH, reaction temperature and water matrix species) were investigated. The results show that the catalytic degradation efficiency of ATZ increases with the increase in PMS concentration and temperature, whereas a higher content of WTRs results in lower removal efficiency because of the quenching effect and negative effect of high pH. For an initial solution pH of 3 and 5, 94.1% and 87.4% of ATZ degradation can be achieved within 6 h, whereas the value is only 26% for pH of 7. The production of sulfate radicals (SO4 center dot-) and hydroxyl radicals ((OH)-O-center dot) was confirmed by classic radical quenching and electron spin resonance (ESR) tests. Based on the GC-MS and LC-MS results, the main degradation pathways of ATZ may contain dealkylation, dechlorination-hydroxylation, and alkyl chain oxidation processes. In addition to the ATZ removal ability, the WTRs/PMS system can simultaneously remove phosphorus. This article provides a new idea for wastewater treatment and usage of WTRs as a resource. (C) 2017 Elsevier B.V. All rights reserved.