Assessing the feasibility of a downstream heterogeneous Fenton process for the oxidative degradation of biologically treated ranitidine, diclofenac, and simvastatin

[Display omitted] •Acid treatment increased the zeolite hydrophobicity and specific surface area.•Size-exclusion effect prevented simvastatin degradation.•After using the catalyst 5 times (batches), 1.8% of the initial Fe content leached.•82% (diclofenac) and 98% (ranitidine) degradation after 12 min (continuous regime) This work assesses the feasibility of coupling the heterogeneous Fenton process to biologically treated domestic sewage to remove diclofenac, ranitidine, and simvastatin (50 µg L−1 each). The catalyst was a purified natural zeolite, which was impregnated with iron (2Fe4A). First, batch tests (10 g L−1 catalyst, 2 g L−1 H2O2, and pH 7) were performed to gather information about the performance of the process. Simvastatin could not be significantly removed as its molecular dimensions were larger than the zeolite pores. Drugs removal by adsorption and mineralization were not observed. After five cycles of 30 h each, leached iron was approximately 2%, with no significant change in the drugs removal performance. Second, a fixed-bed reactor packed with 2Fe4A was placed after the exit of the biological reactor, with hydraulic retention time of 12 min. 98 and 82% of diclofenac and ranitidine, respectively, were removed, as well as 93% of the added hydrogen peroxide. The coupled system was stable for, at least, 10 days. The operating cost of the heterogeneous Fenton process combined to the biological one was estimated and, although diclofenac and ranitidine could be significantly removed in a short period of time, it was concluded that it is a relatively expensive process that has the disadvantages of high hydrogen peroxide consumption and size exclusion effects.