Mehmet KOBYA

Article | 2023 | Journal of Water Process Engineering56

The near-widespread presence of poly- and perfluoroalkyl substances (PFASs) in humans has generated concerns regarding the potential negative impact of these chemicals on human health, as some PFASs are exceedingly persistent and bioaccumulative. Among the perfluorinated PFASs, which exhibit high polarity and strong carbon–fluorine bonds, perfluorooctanesulfonate (PFOS) is one of the frequently encountered species. In this study, the efficiency of electrooxidation (EO) and its application in groundwater simulation were first evaluated as a realistic approach to PFOS removal. After optimizing EO parameters including the solution pH, . . .current density, and the effects of inlet concentration and the anode material, 83 total organic carbon (TOC) removal was obtained. In groundwater experiments, in which the infiltration of PFOS from soil layers into groundwater was simulated, 79 TOC removal efficiency was achieved in the more complex groundwater; moreover, an F− ion concentration of 8.78 mg/L was obtained from the decomposition of PFOS. To increase the realism of the simulation, the leachate process was repeated four times, and the EO process was applied to each sequential leachate. In addition, the process efficiency was studied in real landfill leachate wastewater to which PFOS had been added. Despite the challenging wastewater composition, 84 TOC removal efficiency was achieved. Together, these results indicate that BDD-anodic oxidation may be a practical method to treat PFOS-contaminated groundwater and wastewater. Keyword: electrochemical treatment; groundwater treatment; landfill leachate treatment; PFAS More less

Mehmet KOBYA

Article | 2020 | Journal of Water Process Engineering38

Anesthetic gas plant wastewater (AGPW) contains high concentrations of ammonia (NH3-N) and sulphate ions, which is known to results in severe environmental pollution in aquatic ecosystems without treatment. In the first stage of this study, a lab-scale investigation was done to improve removal of ammonia from AGPW by air stripping and struvite (or MAP: magnesium ammonium phosphate) precipitation processes, separately. The main operating parameters such as pH, air flow rate (L/min) and operating time were optimized for air stripping. The theoretical amount of removed ammonia via the air stripping process was calculated. The NH3-N rem . . .oval efficiency reached 94 ?t pH 12. On the other hand, the optimum ratio of [Mg2 ]: [NH4 ]: [PO43-] was determined to be 1:1.1:1.8 for the struvite precipitation. The concentration of NH3-N was reduced from 10,600 to 1680 mg/L at pH 8.0 and the corresponding removal efficiency was 84 ?t optimum ration of MAP. The solution remained after the struvite precipitation was reacted with Ca(OH)(2) at pH values in the range 10-13 for removal of sulphate in the second stage. The removal efficiencies at the optimum conditions were 98 ?or sulphate, 31 ?or COD and 20 ?or TOC. Air stripping process and struvite precipitation could be considered an effective technology for removal and recovery of ammonia or ammonium ion (NH4 -N) from the AGPW. Surface analyses of the precipitated samples were characterized by SEM and XRD More less