## 1 Introduction  
Odors emitted from environmental facilities, such as livestock farms, sewage treatment plants, and food waste treatment facilities, are unpleasant and prompt complaints from the adjacent residents [1, 2, 3]. In particular, the generation of highly concentrated odors can cause discomfort, even with a small leak. Therefore, people detest construction of environmental facilities in proximity to their residences and their backyards. In general, odor gases emitted from such facilities include various substances, such as sulfur and nitrogen compounds, acetaldehyde, and organic acids [4]. Conventional technologies, such as adsorption and absorption, cannot suppress the problems generated due to mixed odor gases [5]. To overcome this setback, multistage chemical scrubbing technology is widely used [6]. Chemical scrubbing maximizes the absorption performance by adjusting the pH, using chemicals to absorb the target pollutants or by inducing the oxidation of the absorbed pollutants via the addition of oxidants. However, the use of chemicals, such as HCl, H\({}_{2}\)SO\({}_{4}\), and NaOH, for wet scrubbing can incur significant costs due to waste treatment solutions. Furthermore, determining the appropriate dosage of chemicals is difficult and the storage of chemicals requires huge containers [7]. In this study, a reactive absorption process, which combines water scrubbing and electrochemical oxidation (electrolyzed water scrubber, EWS), was developed to solve the drawbacks of chemical scrubbing. Electrolyzing water generates reactive chlorine species (RCS), such as HOCI, by applying an electrical potential to water containingCl\({}^{-}\) electrolyte [8]. Electrochemical treatment is widely used in wastewater treatment processes [9]. If electrolyzed water is used as an aqueous solution, the absorption capacity of the aqueous solution can be retained by oxidizing pollutants in the solution. Therefore, EWS supports low costs and easy maintenance, compared to chemical scrubbing. Moreover, electrochemical generation of the RCS can be automated and controlled by adjusting the energy applied [10]. We tried to apply electrochemical oxidation to eliminate air contaminants. H\({}_{2}\)S and NH\({}_{3}\), which are representative odorous substances, were chosen as targets substrates to remove. In a previous study, it was observed that during the simultaneous introduction of H\({}_{2}\)S and NH\({}_{3}\), RCS first oxidized H\({}_{2}\)S, followed by NH\({}_{3}\)[11]. In addition, NH\({}_{3}\) was easily absorbed, even without electrochemical oxidation because it has a higher water solubility than H\({}_{2}\)S. In other words, for EWS, the performance of the entire reactor mainly depends on the inlet concentration of H\({}_{2}\)S. A model to describe the experimental results and predict the removal performance of hydrogen sulfide at fixed inlet concentrations of H\({}_{2}\)S and NH\({}_{3}\) was established in this study. The model was validated at various inlet concentrations, and EWS performance was predicted by varying the inlet concentration of H\({}_{2}\)S, while the concentration of NH\({}_{3}\) was fixed. Several experiments under variable inlet conditions were conducted. Then, a numerical model for predicting EWS performance under various H\({}_{2}\)S inlet concentrations was developed. Modeling reactive absorption is significantly more complex than physical absorption. This is because both mass transfer and chemical reactions occur simultaneously. Particularly, the characteristics of chemical reaction, including reversibility and the reaction rate, make the modeling of reactive absorption more complex [12]. To obtain an accurate model for reactive absorption, a comprehensive understanding is required concerning heat transfer and hydraulics in addition to mass transfer and chemical reaction rates. Simulation of a huge reactor requires differentiation in several subdivisions [13]. In the conventional approach, the partial differential equation (PDE) is generally used for numerical analysis. [PERSON] et al.