BACKGROUND: Both ionic and nonionic ICM are recalcitrant to ozone and traditional waste water treatment plants. In this study, the efficiency of one kind of ICM-iopromide (IOPr) removal from an aqueous solution using a dielectric barrier discharge (DBD) method was investigated. RESULTS: An energy density of 1.5E05 J L1 resulted in the most significant removal (98.8%) of IOPr. At this energy density, no decrease in total organic carbon (TOC) was observed. Based on the IR spectra, degradation of the IOPr molecule involved hydroxylation, carbonylation and deiodination. BOD5/COD measurements indicated that the biodegradability of IOPr increased significantly as a result of DBD treatment. The byproducts of IOPr after DBD treatment were more polar and easily adsorbed and biodegraded by the activated sludge. The removal of IOPr from the solution followed first-order kinetics, with Ks of 0.10 min1, 0.11 min1, 0.44 min1 and 0.15 min1 corresponding to energy densities of 1E + 05 J L1, 1.3E + 05 J L1, 1.5E + 05 J L1 and 1.8E + 05 J L1, respectively. The kinetics of the deiodination reactions were more complex due to subsequent iodide oxidation. CONCLUSION: DBD is very effective as a pretreatment or advanced treatment method for increasing the recalcitrant chemical's biodegradability and making subsequent biological treatment more efficient. (c) 2012 Society of Chemical Industry