Abstract
Volatile organic compounds (VOCs) are intermittently emitted at high concentrations (tens of thousands of ppmv) from small-scale laundry shops in urban areas, affecting the urban atmospheric environment. In this study, we suggested integrating VOC treatment processes incorporating condensation and adsorption in series to remove VOCs released from small-scale laundry dryers (laundry weighing less than 30 kg). We designed two different processes depending on regeneration modes for adsorber beds; an open-circuit flow process and a closed-loop flow process in regeneration mode. Our VOC treatment processes enable sustainable operation via the regeneration of adsorbers on a regular basis. Before applying the VOC treatment processes, average concentration of total volatile organic compounds (TVOCs) was 4099 ppmv (12,000 ppmv of the peak concentration) during the drying operation. After applying our closed-loop flow process, TVOC concentration decreased to 58 ppmv, leading to 98.5% removal efficiency. We also verified the robustness of our process performance in a continuous operation (30 cycles) by using a process simulation program. Lastly, we observed that our integrated treatment process can contribute to reductions in ozone and secondary organic aerosol generation by 90.4% and 95.9%, respectively. We concluded that our integrated VOC treatment processes are applicable to small-scale laundry shops releasing high-concentration VOCs intermittently, and are beneficial to the atmospheric environment.
Highlights
Published: 14 September 2021Volatile organic compounds (VOCs) originate from natural and/or anthropogenic emission sources, affecting atmospheric environment [1,2,3]
We found the lower condensation temperature led to higher VOC-removal efficiency, and our experimental results fitted with the theoretical removal efficiency obtained from the Antoine equation (Figure S2a)
With toluene as a representative compound, we found that lower space velocity and higher inlet total volatile organic compounds (TVOCs) concentration led to higher adsorption capacity in the adsorber (Figure S3a)
Summary
Volatile organic compounds (VOCs) originate from natural and/or anthropogenic emission sources, affecting atmospheric environment [1,2,3]. The anthropogenic emission sources of VOCs include internal combustion engine vehicles, large-scale industrial complexes, residential combustion, and solvent use [4,5,6]. Parts of the VOCs have adverse health effects [10,11] and were included in the 187 toxic air pollutants designated by the United States Environmental Protection Agency [12]. Among the various anthropogenic emission sources of VOCs, half of VOC emissions are produced by the use of volatile chemical products in industrialized cities in the United States, while the contribution of vehicle emissions has decreased at the same time [5]. As people in developed countries spend more than 80% of their time indoors [13], human exposure to VOCs in indoor environments, Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
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