Removal efficiencies of emissions of volatile organic compounds by adsorption systems installed in small-scale auto-repair painting operations

Removal efficiencies of emissions of volatile organic compounds by adsorption systems installed in small-scale auto-repair painting operations | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Removal efficiencies of emissions of volatile organic compounds by adsorption systems installed in small-scale auto-repair painting operations Haejoon Chun, Min Young Song This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2102515/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Total hydrocarbon (THC), including volatile organic compounds (VOCs), is emitted during the operations of an auto-repair painting workshop. VOCs are especially hazardous pollutants because of their impacts on ozone formation and human health. To reduce the THC generated from small auto-repair painting shops, the Korean government conducts a support program to enable them to shift from an old to a new adsorption system. Although lab-scale evaluations of the pollutant reduction efficiencies of some adsorption devices have been carried out, actual field evaluations are lacking. In this study, three auto-repair shops (one with an old and two with new air pollutant adsorption systems) in Seoul were selected to evaluate their removal efficiencies with respect to THC and VOCs during painting and drying operations. Results show that the THC removal efficiencies were − 41.3–35.4% and 17.2 − 59.2% for the old and new adsorption systems, respectively. The removal efficiencies of the top five VOC species such as butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene were positive (+) and negative (−) for the new and old adsorption systems, respectively. These results provide a theoretical basis that endorses the government support policy for the removal of air pollutants from the emissions of small businesses that are not well managed, such as auto-repair painting, printing, and dry cleaning. adsorption system automotive painting removal efficiency total hydrocarbon removal volatile organic compound species Figures Figure 1 Figure 2 Figure 3 Introduction Volatile organic compounds (VOCs) have been the focus of environmental concerns related to ozone formation through photochemical reactions (Kim 2011; Wei et al. 2014). VOCs are the main precursors for tropospheric ozone and secondary organic aerosol in urban areas (An et al. 2014; Li et al. 2022; LIU et al. 2020). Especially for ozone depletion, VOCs are released in conjunction with important greenhouse gases, act as atmospheric oxidants and are the most important primary precursors for OH (Bozem et al. 2017; Lelieveld et al. 2004; Monks et al. 2015), thereby causing climate change (Berntsen et al. 1996; Lippmann 1989; Schwartz et al. 1996). Some VOCs are also toxic and are potential threats for human health. Exposure to specific VOCs can affect the reproductive and central nervous systems, cause asthma, and have other deleterious respiratory effects (Rumchev et al. 2007; Venn et al. 2003). Toluene is a VOC that is used as an emission marker for painting operations and it has toxic effects on the nervous and reproductive systems (Wang et al. 2017). Industries that use solvents such as auto repair, and furniture, manufacturing, steel, and ship manufacturing and repairs are major contributors of VOCs (Wang et al. 2017; Wang et al. 2020). Painting is an essential procedure in many industries and various kinds of paints and solvents are applied on different types of surfaces (Wang et al. 2017). In Seoul, the ‘organic solvent usage’ industry contributed 82% of the total emissions of VOCs; of these, painting, printing, and dry-cleaning industries accounted for 38, 11, and 7%, respectively (NAIR 2018). Therefore, the control strategy for VOCs must focus on painting industries to improve the air quality of Seoul. It was estimated that approximately 3,700 auto-repair shops were located in Seoul in 2018 and these form a considerable proportion of the overall painting industry (Molit 2018). In addition, most auto-repair shops that include painting work are small-scale air pollutant emitting businesses. Seoul is a megacity with a population of more than 10 million with a mix of small-scale air pollutant emitting plants and residential areas. It is reported that the concentrations of secondary pollutants in Seoul and surrounding urban areas are higher than those in any other region in Korea (Shin et al. 2013). So far, the management of emission sources of VOCs have focused mainly on large-scale facilities (An et al. 2014; Chen et al. 2019; Shen et al. 2018; Zheng et al. 2017) and small-scale facilities have not received the required attention (Li et al. 2017). In Korea, painting facilities with a volume of 5 m 3 or a power consumption of 2.25 kW or more are bound to adhere to standards for the control of air pollutant emissions. The THC emission standard prescribes an upper limit of 40 and 200 ppm for continuous and discontinuous painting facilities, respectively. Recently, the Korean government has promoted a policy to support the installation of control systems to reduce air pollutant emissions from small-scale plants with a total emission of air pollutants of less than 10 ton/year. In 2020, there were 2,021 air pollutant emitting plants located in Seoul and among them 1,979 (98%) were small-scale plants. The main types of air pollutant emitting industries in the order of decreasing intensity were boilers, painting, and plating. In Seoul, the government supported 138 plants in 2019 and 111 plants in 2020 with the installation of control systems. For painting and plating industries, support was provided for the installation of prevention facilities such as filtration, absorption, and adsorption systems. Activated carbon filters are widely used to control VOCs emitted from painting in auto-repair shops (Metts and Batterman 2006). Methods known for reducing VOCs are condensation, absorption, and adsorption (Belaissaoui et al. 2016; Biard et al. 2017; Pui et al. 2019). Activated carbon, which is used as an adsorbent, has a high removal efficiency and it is economical (Noh et al. 2008). In Korea, an activated carbon tower with multiple activated carbon filters and cartridges is provided in the adsorption system to reduce VOCs emitted from painting in auto-repair shops. The purpose of this study is to evaluate the effectiveness of the Korean government’s air pollution prevention facility replacement support project for small-scale plants. For this purpose, we compared the operation statuses and evaluated the removal efficiencies of old and new adsorption systems. In contrast to previous studies (Afshari et al. 2003; Kozicki and Guzik 2021; Metts and Batterman 2006; Noh et al. 2008; Song et al. 2012; Wang et al. 2020) that tested removal efficiencies at the chamber scale, we conducted in-field studies at three auto-repair shops. In addition, we measured THC concentrations and analyzed VOC species that were emitted during the main operations (painting and drying). Based on these measurements, we calculated the removal efficiencies of the adsorption systems. Based on our analyses, we suggest improvements to the adsorption system to achieve a higher efficiency in terms of air pollutant emission control in small businesses. Materials And Methods 2.1. Measurement sites To investigate and evaluate the operation status of adsorption systems, three automotive-repair shops in Seoul, with one old (Old 1) and two new (New 1 and 2) air pollutant adsorption systems, were selected for our study. Measurements were conducted twice at each shop. For each set of measurements, operation characteristics including duration, quantity of paint used, dilution ratio, THC and VOC species at inlets and outlets were analyzed. Old 1 and New 1 used water-based paint and New 2 used oil-based paint. Old 1 had an old adsorption system that was installed in 2011. New 1 and 2 had new adsorption systems that were installed in 2019 with government support. In all auto-repair shops, measurements were performed during the painting and drying operations. Information on the three auto-repair shops are presented in Table 1). Table 1 Information on the three auto-repair shops in Seoul Year of install ation of adsorption systems P aint t ype used Operation process es Old 1 Old 1-1 2011 Water-based paint Painting and drying Old 1-2 2011 New 1 New 1-1 2019 (Government aid) New 1-2 2019 (Government aid) New 2 New 2-1 2019 (Government aid) Oil-based paint New 2-2 2019 (Government aid) 2.2. Methods of measurements and analyses Measurements of THC and VOC species were conducted throughout the painting and drying operations. The inlet concentrations of THC and VOC species were measured at the bottom of the spray painting booth as painting operations were performed. The outlet concentrations of THC and VOC species were measured after passing through the adsorption systems. The portable Toxic Vapor Analyzer TVA 2020 (Thermo Fisher Scientific, Franklin, MA) equipped with a flame ionization detector (FID) detector was used for real-time monitoring of THC concentrations. The range of measurable concentration was from 1 to 10,000 ppm with an accuracy of ± 10% or ± 1.0 ppm and a reproducibility of ± 2% (at 500 ppm of methane). For the analyses of VOC species, sampling was conducted using the solid adsorption method using Tenax-TA (40/60 mesh, Markers, USA) sorbent tubes. Tenax-TA sorbent tubes were conditioned for 6 h at 300 °C using TC-20 (Markers, USA) prior to measurement (Supplementary Table 1). Sampling of VOCs was conducted for 5 min during the painting and drying operations with a flow rate of 100 ml/min with sorbent tubes filled with Tenax-TA. The flow rate of the sampling pump equipped with the sorbent tube was corrected using a soap film flowmeter before starting measurements. Tenax-TA sorbent tubes were refrigerated at 4 °C or below and analyzed using gas chromatography–mass spectrometry GC/MS (Agilent Technologies, Inc., Agilent HP-6890, USA) (Table S1). As standard substances of the VOCs to be analyzed, 10 CHEM, 50 ozone precursors, and TO-14 of Supelco containing 42 toxic VOCs were used (Table S2). Out of a total of 102 chemicals, 88 were classified by excluding overlapping substances in these standard categories (Table S2). GC/MS analysis was performed using secondary thermal desorption and solvent delay for 5 min to minimize the analysis of the initial low molecular weight material, maintaining a temperature of 50 °C for 10 min, and gradually increasing the temperature to 220 °C. After maintaining the temperature at 220 °C for 10 min, the post run was set to 5 min to reduce the contamination of equipment due to the inflow of polymers other than the compounds to be measured. The analysis of each sample took approximately 54 min. The linearity of the measured VOCs was evaluated using 100 μg/ml of a liquid standard substance (Supelco, USA), which was added in quantities of 100, 300, and 500 ng concentrations into three Tenax-TA sorbent tubes through the adsorbent tube injector system. Based on the linearity evaluation of the calibration curve, the coefficient of determination (R 2 ) was 0.99 or higher and the relative standard deviation, which represents the reproducibility of the analysis, was evaluated at 0.52 to 4.32%. 2.3. Calculation of removal efficiency THC removal efficiency of the adsorption system was calculated using equations (1) –(3). For the average concentrations of the inlet and outlet, flow rate (m 3 /min) and THC concentration (ppm)) were multiplied and divided by the sum of the total flow rate (m 3 /min) for all operations in (1) and (2). The total removal efficiency of the adsorption system was calculated using the difference of the average concentrations of the inlet and outlet divided by average inlet concentration in (3). VOC species removal efficiency of the adsorption system at the outlet was calculated using equation (4). VOC species removal efficiency for each species was calculated using the difference of the average concentrations at the inlet and outlet divided by the inlet concentration (4). Results 3.1 Comparison of old and new adsorption systems Information on the volume of the adsorption system, area of cartridge, number of cartridges, total area, thickness, volume, and quantity of activated carbon at each auto-repair shop are summarized in Table 2. All the three auto-repair shops used activated carbon cartridges to remove the THC emitted from the processes. For Old 1, the maintenance and control status of the equipped activated carbon was insufficient to remove the emitted pollutants. Especially, for Old 1, the quantity of activated carbon was 120 kg, which is the lowest compared to New 1 and 2 (510 and 340 kg, respectively). In addition, the thickness of activated carbon filter, area, and volume were low in all three shops, indicating poor maintenance and control including lack of regular checking of adsorption efficiency and replacement of activated carbon. Table 2 Information on adsorption systems of the three auto-repair shops Auto-repair shops Volume of adsorption system (W × L × H) (m) Activated carbon Area of cartridge Number of Cartridges Total area Thickness Volume Quantity (m 2 ) (m 2 ) (mm) (m 3 ) (kg) Old 1 (1 and 2) 2.0 × 1.6 × 2.8 1.2 4 4.8 50 0.24 120 New 1 (1 and 2) 2.0 × 2.0 × 2.6 2.6 4 10.2 100 1.02 510 New 2 (1 and 2) 2.0 × 1.5 × 3.0 1.3 6 7.6 90 0.68 340 Flow rates of adsorption systems were measured during painting and drying operations (Table 3). Overall, the measured flow rates of adsorption systems of all three auto-repair shops were considerably different compared to that of their designs. The designed flow rate of the three shops was 380–400 S m 3 /min to remove pollutants; however, the actual flow rates were 2.3–22.2% of their design flow rates (Old 1-1: 18.9%, Old 1-2: 14.9%, New 1-1: 2.3%, New 1-2: 3.0%, New 2-1: 22.2%, and New 2-2: 11.4%). Insufficient quantity and irregular replacement of activated carbon and maintaining a low flow rate during operations can lead to the detachment of the adsorbent or in decreased adsorption efficiency (Song and Chun 2021). Table 3 Flow rates of adsorption systems of the three auto-repair shops Auto-repair shops Design flow rate Measured flow rate Paint Dry Total (S m 3 /min) (S m 3 /min) (S m 3 /min) (S m 3 /min) Old 1 (1-1) 380 208.2 12.2 71.7 Old 1 (1-2) 187.5 11.4 56.8 New 1 (1-1) 400 35.6 2.9 9.1 New 1 (1-2) 39.8 6.4 12.0 New 2 (2-1) 380 313.6 4.6 84.2 New 2 (2-2) 211.0 20.2 43.2 3.2. Emitted THC concentrations of old and new adsorption systems The emitted THC concentrations during auto-repair operations were measured using a portable FID detector. Figure 1 shows the variations in emission rates with time of the painting and drying operations of the three auto-repair shops. In all the auto-repair shops, the THC emission rates increased rapidly as the painting operation started and after peaking they decreased with regular fluctuations. The periodicity of the fluctuations in emission rates were different for the ‘Old’ and ‘New’ adsorption systems. In the case of Old 1-1, the fluctuation in the THC outlet concentration was higher than that of the inlet concentration. The THC concentration ranged from 2 to 248 ppm for the old adsorption system (Old 1) and it ranged from 0 to 496 ppm for the new adsorption system (New 1 and 2) for both inlets and outlets. In both adsorption systems, there was a delay between the THC inlet and outlet measurements. A peak in the THC concentration at the inlet was immediately followed by a peak at the outlet. The THC concentration at the outlet was higher than that at the inlet concentration in Old 1-1. In Old 1-1, 32 min after the start of the operation, the THC outlet concentration became higher than that of the inlet, and remained high. These reverse fluctuations indicate as follows: 1) The adsorption system did not work efficiently to reduce the emission of pollutants during the painting and drying operations; 2) Unremoved substances from the adsorption systems can disperse and affect the air quality of surrounding areas. Compared to Old 1, New 1 and 2 showed a stable fluctuation, that is, the THC concentrations of outlets were lower than that of inlets during operations. Therefore, the new adsorption systems effectively remove emitted pollutants. The THC concentrations detected during the painting and drying operations at the inlets and outlets of the auto-repair shops are presented in Table 3. The total THC concentration ranged from 1.7 × 10 3 to 6.3 × 10 5 ppm for all auto-repair shops. For Old 1-1, the THC concentration at the outlet (5.4 × 10 5 ppm) was higher than that at the inlet (3.8 × 10 5 ) for both operations. In other adsorption systems, the concentrations at the inlets (Old 1-2: 4.4 × 10 5 , New 1-1: 1.2 × 10 5 , New 1-2: 2.5 × 10 5 , New 2-1: 6.3 × 10 5 , New 2-2: 4.3 × 10 5 ) were lower than those of the outlets (Old 1-2: 2.8 × 10 5 , New 1-1: 1.0 × 10 5 , New 1-2: 1.0 × 10 5 , New 2-1: 4.1 × 10 5 , New 2-2: 2.4 × 10 5 ) because the pollutants were removed and the THC concentration decreased. Table 3 THC removal efficiency of auto-repair operations Auto-repair shop Operation Measurement location Total THC concentration (ppm) Total flow rate (m 3 /min) Removal efficiency (%) Average THC concentration (ppm) Old 1 (1-1) Painting Inlet 3.4 × 10 5 11,242 −47.7 29.6 Outlet 5.0 × 10 5 43.5 Drying Inlet 4.3 × 10 4 1,515 9.8 27.3 Outlet 3.8 × 10 4 25.6 Total Inlet 3.8 × 10 5 12,757 −41.3 28 Outlet 5.4 × 10 5 31 Old 1 (1-2) Painting Inlet 4.2 × 10 5 8,064 39 49 Outlet 2.6 × 10 5 30.5 Drying Inlet 1.9 × 10 4 1,419 −43.9 12.9 Outlet 2.7 × 10 4 19.2 Total Inlet 4.4 × 10 5 9,483 35.4 22.2 Outlet 2.8 × 10 5 22.1 New 1 (1-1) Painting Inlet × 10 5 1,032 20.5 98 Outlet 8.1 × 10 4 77.8 Drying Inlet 2.0 × 10 4 358 0.7 38.5 Outlet 2.0 × 10 4 26.3 Total Inlet 1.2 × 10 5 1,390 17.2 49.8 Outlet × 10 5 36.1 New 1 (1-2) Painting Inlet 2.0 × 10 5 4,588 66.6 204 Outlet 6.7 × 10 4 68.8 Drying Inlet 5.0 × 10 4 795 29.5 43 Outlet 3.5 × 10 4 23.9 Total Inlet 2.5 × 10 5 5,382 59.2 70 Outlet 1.0 × 10 5 31.5 New 2 (2-1) Painting Inlet 6.3 × 10 5 13,487 34.9 45.9 Outlet 4.1 × 10 5 30 Drying Inlet 3.8 × 10 3 566 55.4 11.4 Outlet 1.7 × 10 3 3.6 Total Inlet 6.3 × 10 5 14,053 35.1 20.3 Outlet 4.1 × 10 5 10.4 New 2 (2-2) Painting Inlet 3.9 × 10 5 3,586 48 108.3 Outlet 2.0 × 10 5 56.2 Drying Inlet 4.1 × 10 4 2,507 10 16.7 Outlet 3.7 × 10 4 3.3 Total Inlet 4.3 × 10 5 6,093 44.4 27.8 Outlet 2.4 × 10 5 9.7 3.3. THC removal efficiency Table 3 shows the removal efficiencies of adsorption systems of the three auto-repair shops, which were calculated based on total flow rates and the total of inlet and outlet concentrations. The total THC emissions (ppm) in both operations were divided by total flow rate (m 3 /min) at each inlet and outlet. For all auto-repair shops, the removal efficiency ranged from −41.3 to 59.2%. The order of removal efficiency for both operations in the three auto-repair shops was as follows: New 1-2 (59.2%) > New 2-2 (44.4%) > New 2-1 (35.1%) > Old 2 (35.4%) > New 1 (17.2%) > Old 1 (−41.3%). It has been reported that in same auto-repair shops, the removal efficiency was different because of multiple factors that affect adsorption efficiency such as quantity of paint used, operation time, and workers’ characteristics (Wang et al. 2017). For Old 1-1, in the painting operation, the total THC concentration of the inlet was 3.4 × 10 5 ppm and that of the outlet was 5.0 × 10 5 ppm, which results in a removal efficiency of −47.7%. For Old 1-2, in the drying operation, the total THC concentration of the inlet was 1.9 × 10 4 ppm and outlet was 2.7 × 10 4 ppm, which results in a removal efficiency of −43.9%. In addition, for Old 1-1, in the painting operation, the average concentration of the inlet was 29.6 ppm and that of the outlet was 43.5 ppm, which is 1.47 times higher than that of the inlet. For Old 1-2, in the drying operation, the average concentration of the inlet was 12.9 ppm and that of the outlet was 19.2 ppm, which is 1.49 times higher than that of the inlet. This negative removal efficiency can be explained by three factors: 1) The flow rate of the adsorption system was not adequate to remove the chemicals emitted during operations (Noh et al. 2008). In the case of Old 1-2, the total flow rate decreased from 8,064 m 3 /min to 1,419 m 3 /min, and because of this rapid decrease in flow rate by 82.4%, the pollutants emitted during the painting and drying operations were adsorbed by the adsorbent; 2) The accumulated chemicals that were attached to the adsorbent in previous operations disrupted the removal process of the newly emitted chemicals. Except for New 2, in all other cases, water-based paint was used and oil-based paint was only used occasionally. The use of oil-based paints can result in higher concentrations of VOCs compared to the use of water-based paints (Song and Chun 2021); moreover, oil-based paints can lead to the accumulation of emitted pollutants, thereby affecting the adsorption process. 3.4. Removal efficiency of VOC species Eighty-eight VOC species, including 5 CHEM, 33 TO-14, and 50 ozone precursor compounds, were analyzed. Analysis of the VOCs was performed by focusing on the dry phase, which is the endpoint of the operations. The concentrations of the top five species of VOCs are presented in Fig. 2 and Table S4. Removal efficiencies of the auto-repair shops are shown in Fig. 3. Detailed results are provided in Table S5. Based on the total concentration at the inlet and outlet in the dry phase, the top five VOCs were identified as butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene. These were also detected in many previous studies (Kim et al. 2020; Park et al. 2008). The inlet concentration of the top five VOC species for Old 1-1, Old 1-2, New 1-1, New 1-2, New 2-1, and New 2-2 were 45−1,231, 73−1,256 260−2,503, 587−2,997, 78−1,034, and 158−1,256 ppm, respectively. Comparatively, the inlet concentrations for Old 1-1, Old 1-2, New 1-1, New 1-2, New 2-1, and New 2-2 were 121−1,478, 135−2.465, 199−2,081, 288−2,338, 61−743, and 95−902 ppm, respectively. Overall, in the case of the old adsorption system, the outlet concentrations of the top five species were higher than those of the inlet. For New 1 and 2, which are equipped with the new adsorption systems, the outlet concentrations were lower than those of the inlet. Figure 3 shows that the top five VOC species achieved a positive (+) removal efficiency at New 1–2 while it was negative (−) at Old 1. The removal efficiencies of the top five VOC species ranged from −178.4 to −11.6% in Old 1-1 and −96.2 to −3.5% in Old 1-2. On the contrary, the removal efficiency of New 1 ranged from 5.8 to 65.3% and of New 2 ranged from 21.4 to 54.0%, indicating a high removal efficiency. It was estimated that the VOC compounds generated from former operations were desorbed during this measurement and the adsorbent (activated carbon) had a low adsorption capacity because of its irregular replacement. Discussion We analyzed the removal efficiencies of THC and VOCs for old and new adsorption systems. We confirmed that the removal efficiency was high in the new adsorption system. Recently, the Korean government implemented a policy to support small-scale auto-repair shops by replacing their old adsorption systems with new adsorption systems. Therefore, our findings provide support to extend this program to improve the removal efficiencies of THC and VOCs that are emitted from auto-repair shops. The removal efficiencies of THC and VOC species were the highest in New 1–2. Contrastingly, in the old auto-repair shops, the removal efficiencies were negative (−) at −47.7% during the painting operation in Old 1-1 and −43.9% during the drying operation in Old 1-2. The removal efficiencies were negative for the top five VOC species in Old 1–2, ranging from −178.4 to −3.5% and positive in New 1–2 at 5.8–65.3%. We confirmed the significance of replacing the adsorption system with the newly designed system that consists of increased quantity and thickness of activated carbon with a better replacement cycle to efficiently recover the VOCs emitted from the painting and drying operations. To design an adsorption system with a high removal efficiency, it is necessary to consider the characteristics of commonly used paints including their contents of aromatic hydrocarbons, aliphatic hydrocarbons, esters, ketones, alcohols, and glycol ethers (Kim 2011). In our study, the top five VOCs were butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene, which are aromatic hydrocarbons. Aromatic hydrocarbons contribute significantly to the formation of ozone, other photooxidants, and secondary organic aerosols in urban atmospheres (Luo et al. 2021). Therefore, when choosing the adsorbent or activated carbon in the adsorption system, it is necessary to consider the characteristics of VOCs. Moreover, there is need to manage and control the main operations that produce high VOCs emissions. In a previous study on auto-assembly plants, spray painting (primers and top coats) were the major sources of VOCs and about 70–80% of the VOCs were generated from the spray booth (Chang et al. 2002). Therefore, during the spraying operation, the management should focus on providing an adequate flow rate to facilitate the capture of VOCs through regular and timely replacement of cartridges and check the breakthrough (saturation) point of the activated carbon frequently. Conclusion The trends of THC emitted from old and new adsorption systems of auto-repair shops in Korea were identified. In the old adsorption system, reverse fluctuation was observed wherein the THC concentration at the outlet was higher than that of the inlet. We compared the removal efficiencies of emitted THC and VOCs of the old and new adsorption systems. The removal efficiency of the new adsorption system was 17.2–59.2% and that of the old adsorption system was −41.3–35.4%. The top five VOCs that were captured at the outlet were butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene, which are aromatic hydrocarbons. In particular, for each VOC species, The removal efficiencies for the top five VOCs were positive (+) in the new adsorption system and negative (−) in the old adsorption system. Our findings provide a scientific basis for implementing appropriate control and effective management of adsorption systems in auto-repair shops to efficiently remove emitted VOCs from painting and drying operations. In addition, our study can lead to improvements in implementing policies that provide installation support for small businesses toward achieving a better VOC removal efficiency in the future. Declarations Acknowledgements This research was supported by the Seoul Institute of Technology (SIT) (2021-AE-002) Competing interests The authors have no relevant financial or non-financial interests to disclose. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Haejoon Chun and Min Young Song. The first draft of the manuscript was written by Haejoon Chun and Min Young Song and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Data Availability All data are provided in the manuscript. References Afshari A, Lundgren B,Ekberg L E (2003) Comparison of three small chamber test methods for the measurement of VOC emission rates from paint. 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Ministry of Land, Infrastructure and Transport (2018) Status of automobile repair companies in Korea. https://stat.molit.go.kr/portal/main/portalMain.do National Air Emission Inventory and Research Center (2018) National air pollutants emission. (National Center for Fine Dust Information, 2018). https://www.air.go.kr/jbmd/sub37.do?tabPage=0 Noh S-Y, Kim K-H, Choi J-H, Han S-D, Kil I-S, Kim D-H,Rhee Y-W (2008) Adsorption characteristics of VOCs in activated carbon beds. Journal of Korean Society for Atmospheric Environment 24:455–469. https://dx.doi.org/10.5572/KOSAE.2008.24.4.455 . Park J-H, Suh J-M,Han S-J (2008) Characteristics of atmospheric concentrations of volatile organic compounds and aldehydes for near a shipyard. Journal of Environmental Science International 17:767–774. https://dx.doi.org/10.5322/JES.2008.17.7.767 . Pui W K, Yusoff R,Aroua M K (2019) A review on activated carbon adsorption for volatile organic compounds (VOCs). Reviews in Chemical Engineering 35:649–668. https://dx.doi.org/10.1515/revce-2017-0057 . Rumchev K, Brown H,Spickett J (2007) Volatile organic compounds: do they present a risk to our health? Reviews on environmental health 22:39–56. https://dx.doi.org/10.1515/REVEH.2007.22.1.39 . Schwartz J, Dockery D W,Neas L M (1996) Is daily mortality associated specifically with fine particles? Journal of the Air & Waste Management Association 46:927–939. https://dx.doi.org/10.1080/10473289.1996.10467528 . Shen L, Xiang P, Liang S, Chen W, Wang M, Lu S,Wang Z (2018) Sources profiles of volatile organic compounds (VOCs) measured in a typical industrial process in Wuhan, Central China. Atmosphere 9:297. https://dx.doi.org/10.3390/atmos9080297 . Shin H, Kim J, Lee S,Kim Y (2013) Evaluation of the optimum volatile organic compounds control strategy considering the formation of ozone and secondary organic aerosol in Seoul, Korea. Environmental Science and Pollution Research 20:1468–1481. https://dx.doi.org/10.1007/s11356-012-1108-5 . Song B-J, Lee S-M, Cho G-J, Cho J-G, You P-J,Kim G-G (2012) VOC/HAPs emission characteristics & adsorption evaluation for paint products in Busan area. Journal of Korean Society of Environmental Engineers 34:316–325. https://dx.doi.org/10.4491/KSEE.2012.34.5.316 . Song M,Chun H (2021) Species and characteristics of volatile organic compounds emitted from an auto-repair painting workshop. Scientific reports 11:1–9. https://dx.doi.org/10.1038/s41598-021-96163-4 . Venn A, Cooper M, Antoniak M, Laughlin C, Britton J,Lewis S (2003) Effects of volatile organic compounds, damp, and other environmental exposures in the home on wheezing illness in children. Thorax 58:955–960. https://dx.doi.org/10.1136/thorax.58.11.955 . Wang D, Nie L, Shao X,Yu H (2017) Exposure profile of volatile organic compounds receptor associated with paints consumption. Sci Total Environ 603–604:57–65. https://dx.doi.org/10.1016/j.scitotenv.2017.05.247 . Wang M, Qin W, Chen W, Zhang L, Zhang Y, Zhang X,Xie X (2020) Seasonal variability of VOCs in Nanjing, Yangtze River delta: Implications for emission sources and photochemistry. Atmospheric Environment 223:117254. https://dx.doi.org/10.1016/j.atmosenv.2019.117254 . Wei W, Cheng S, Li G, Wang G,Wang H (2014) Characteristics of volatile organic compounds (VOCs) emitted from a petroleum refinery in Beijing, China. Atmospheric Environment 89:358–366. https://dx.doi.org/10.1016/j.atmosenv.2014.01.038 . Zheng C, Shen J, Zhang Y, Huang W, Zhu X, Wu X, Chen L, Gao X,Cen K (2017) Quantitative assessment of industrial VOC emissions in China: Historical trend, spatial distribution, uncertainties, and projection. Atmospheric Environment 150:116–125. https://dx.doi.org/10.1016/j.atmosenv.2016.11.023 . Additional Declarations No competing interests reported. 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THC: Total hydrocarbon\u003c/p\u003e","description":"","filename":"F1.png","url":"https://assets-eu.researchsquare.com/files/rs-2102515/v1/407c4eeedb0690462de2bb44.png"},{"id":27139965,"identity":"5add579e-e10b-43c2-bafe-4ab5567fecdb","added_by":"auto","created_at":"2022-09-29 14:52:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":142206,"visible":true,"origin":"","legend":"\u003cp\u003eConcentrations of VOC species that were measured at outlets during auto-repair operations in (a) Old 1-1, (b) Old 2-1, (c) New 1-1, (d) New 1-2, (e) New 2-1, and (f) New 2-2\u003c/p\u003e","description":"","filename":"F2.png","url":"https://assets-eu.researchsquare.com/files/rs-2102515/v1/2000e2813705f3dddfdce884.png"},{"id":27138106,"identity":"5846c9a8-d711-4583-b22a-7b73213f9d1e","added_by":"auto","created_at":"2022-09-29 14:42:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":26688,"visible":true,"origin":"","legend":"\u003cp\u003eRemoval efficiencies of VOC species in old and new adsorption systems\u003c/p\u003e","description":"","filename":"F3.png","url":"https://assets-eu.researchsquare.com/files/rs-2102515/v1/20ebda40620023e51adb11be.png"},{"id":27640464,"identity":"cfc3c30d-6920-4e55-a6e6-879c9442d9f5","added_by":"auto","created_at":"2022-10-11 19:29:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":837618,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2102515/v1/58aacc01-f58d-4c7e-8c3c-e281027dfd4f.pdf"},{"id":27138109,"identity":"d139b6c7-e7a9-47d3-a542-ca563e118129","added_by":"auto","created_at":"2022-09-29 14:42:12","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":40119,"visible":true,"origin":"","legend":"","description":"","filename":"2.SupplementaryInformation0926.docx","url":"https://assets-eu.researchsquare.com/files/rs-2102515/v1/767b69620b7446608db6ed81.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Removal efficiencies of emissions of volatile organic compounds by adsorption systems installed in small-scale auto-repair painting operations","fulltext":[{"header":"Introduction","content":"\u003cp\u003eVolatile organic compounds (VOCs) have been the focus of environmental concerns related to ozone formation through photochemical reactions\u0026nbsp;(Kim 2011; Wei et al. 2014). VOCs are the main precursors for tropospheric ozone and secondary organic aerosol in urban areas\u0026nbsp;(An et al. 2014; Li et al. 2022; LIU et al. 2020). Especially for ozone depletion, VOCs are released in conjunction with important greenhouse gases, act as atmospheric oxidants and are the most important primary precursors for OH\u0026nbsp;(Bozem et al. 2017; Lelieveld et al. 2004; Monks et al. 2015), thereby causing climate change\u0026nbsp;(Berntsen et al. 1996; Lippmann 1989; Schwartz et al. 1996). Some VOCs are also toxic and are potential threats for human health. Exposure to specific VOCs can affect the reproductive and central nervous systems, cause asthma, and have other deleterious respiratory effects\u0026nbsp;(Rumchev et al. 2007; Venn et al. 2003). Toluene is a VOC that is used as an emission marker for painting operations and it has toxic effects on the nervous and reproductive systems\u0026nbsp;(Wang et al. 2017).\u003c/p\u003e\n\u003cp\u003eIndustries that use solvents such as auto\u0026nbsp;repair, and furniture, manufacturing, steel, and ship manufacturing and repairs are major contributors of VOCs\u0026nbsp;(Wang et al. 2017; Wang et al. 2020). Painting is an essential procedure in many industries and various kinds of paints and solvents are applied on different types of surfaces\u0026nbsp;(Wang et al. 2017). In Seoul, the \u0026lsquo;organic solvent usage\u0026rsquo; industry contributed 82% of the total emissions of VOCs; of these, painting, printing, and dry-cleaning industries accounted for 38, 11, and 7%, respectively (NAIR 2018). Therefore, the control strategy for VOCs must focus on painting industries to improve the air quality of Seoul. It was estimated that approximately 3,700 auto-repair shops were located in Seoul in 2018 and these form a considerable proportion of the overall painting industry (Molit 2018). In addition, most auto-repair shops that include painting work are small-scale air pollutant emitting businesses.\u003c/p\u003e\n\u003cp\u003eSeoul is a megacity with a population of more than 10 million with a mix of small-scale air pollutant emitting plants and residential areas.\u0026nbsp;It is reported that the concentrations of secondary pollutants in Seoul and surrounding urban areas are higher than those in any other region in Korea\u0026nbsp;(Shin et al. 2013). So far, the management of emission sources of VOCs have focused mainly on large-scale facilities\u0026nbsp;(An et al. 2014; Chen et al. 2019; Shen et al. 2018; Zheng et al. 2017)\u0026nbsp;and small-scale facilities have not received the required attention\u0026nbsp;(Li et al. 2017). In Korea, painting facilities with a volume of 5 m\u003csup\u003e3\u003c/sup\u003e or a power consumption of 2.25 kW or more are bound to adhere to standards for the control of air pollutant emissions. The THC emission standard prescribes an upper limit of 40 and 200 ppm for continuous and discontinuous painting facilities, respectively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRecently, the Korean government has promoted a policy to support the installation of control systems to reduce air pollutant emissions from small-scale plants with a total emission of air pollutants of less than 10 ton/year. In 2020, there were 2,021 air pollutant emitting plants located in Seoul and among them 1,979 (98%) were small-scale plants. The main types of air pollutant emitting industries in the order of decreasing intensity were boilers, painting, and plating. In Seoul, the government supported 138 plants in 2019 and 111 plants in 2020 with the installation of control systems. For painting and plating industries, support was provided for the installation of prevention facilities such as filtration, absorption, and adsorption systems.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Activated carbon filters are widely used to control VOCs emitted from painting in auto-repair shops\u0026nbsp;(Metts and Batterman 2006). Methods known for reducing VOCs are condensation, absorption, and adsorption\u0026nbsp;(Belaissaoui et al. 2016; Biard et al. 2017; Pui et al. 2019). Activated carbon, which is used as an adsorbent, has a high removal efficiency and it is economical\u0026nbsp;(Noh et al. 2008). In Korea, an activated carbon tower with multiple activated carbon filters and cartridges is provided in the adsorption system to reduce VOCs emitted from painting in auto-repair shops.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe purpose of this study is to evaluate the effectiveness of the Korean government\u0026rsquo;s air pollution prevention facility replacement support project for small-scale plants. For this purpose, we compared the operation statuses and evaluated the removal efficiencies of old and new adsorption systems. In contrast to previous studies (Afshari et al. 2003; Kozicki and Guzik 2021; Metts and Batterman 2006; Noh et al. 2008; Song et al. 2012; Wang et al. 2020) that tested removal efficiencies at the chamber scale, we conducted in-field studies at three auto-repair shops. In addition, we measured THC concentrations and analyzed VOC species that were emitted during the main operations (painting and drying). Based on these measurements, we calculated the removal efficiencies of the adsorption systems. Based on our analyses, we suggest improvements to the adsorption system to achieve a higher efficiency in terms of air pollutant emission control in small businesses.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003e\u003cstrong\u003e2.1. Measurement sites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;To investigate and evaluate the operation status of adsorption systems, three automotive-repair shops in Seoul, with one old (Old 1) and two new (New 1 and 2) air pollutant adsorption systems, were selected for our study. Measurements were conducted twice at each shop. For each set of measurements, operation characteristics including duration, quantity of paint used, dilution ratio, THC and VOC species at inlets and outlets were analyzed. Old 1 and New 1 used water-based paint and New 2 used oil-based paint. Old 1 had an old adsorption system that was installed in 2011. New 1 and 2 had new adsorption systems that were installed in 2019 with government support. In all auto-repair shops, measurements were performed during the painting and drying operations. Information on the three auto-repair shops are presented in Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e1\u003c/strong\u003e Information on the three auto-repair shops in Seoul\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" width=\"30.612244897959183%\"\u003e\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\" width=\"28.571428571428573%\"\u003e\u003cstrong\u003eYear of install\u003c/strong\u003e\u003cstrong\u003eation of adsorption\u003c/strong\u003e\u003cbr\u003e\u003cstrong\u003esystems\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\" width=\"19.387755102040817%\"\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003cstrong\u003eaint\u003c/strong\u003e\u003cbr\u003e\u003cstrong\u003et\u003c/strong\u003e\u003cstrong\u003eype\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;used\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.428571428571427%\"\u003e\u003cstrong\u003eOperation process\u003c/strong\u003e\u003cstrong\u003ees\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"18.556701030927837%\"\u003eOld 1\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"11.34020618556701%\"\u003eOld 1-1\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\"\u003e2011\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"4\" width=\"19.587628865979383%\"\u003eWater-based paint\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"6\" width=\"21.649484536082475%\"\u003ePainting and drying\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.205128205128204%\"\u003eOld 1-2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"71.7948717948718%\"\u003e2011\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"31.57894736842105%\"\u003eNew 1\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"19.29824561403509%\"\u003eNew 1-1\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"49.12280701754386%\"\u003e2019 (Government aid)\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.205128205128204%\"\u003eNew 1-2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"71.7948717948718%\"\u003e2019 (Government aid)\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"23.68421052631579%\"\u003eNew 2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.473684210526315%\"\u003eNew 2-1\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"36.8421052631579%\"\u003e2019 (Government aid)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"25%\"\u003eOil-based paint\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.205128205128204%\"\u003eNew 2-2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"71.7948717948718%\"\u003e2019 (Government aid)\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. Methods of measurements and analyses\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMeasurements of THC and VOC species were conducted throughout the painting and drying operations. The inlet concentrations of THC and VOC species were measured at the bottom of the spray painting booth as painting operations were performed. The outlet concentrations of THC and VOC species were measured after passing through the adsorption systems.\u003c/p\u003e\n\u003cp\u003eThe portable Toxic Vapor Analyzer TVA 2020 (Thermo Fisher Scientific, Franklin, MA) equipped with a flame ionization detector (FID) detector was used for real-time monitoring of THC concentrations. The range of measurable concentration was from 1 to 10,000 ppm with an accuracy of \u0026plusmn; 10% or \u0026plusmn; 1.0 ppm and a reproducibility of \u0026plusmn; 2% (at 500 ppm of methane).\u003c/p\u003e\n\u003cp\u003eFor the analyses of VOC species, sampling was conducted using the solid adsorption method using Tenax-TA (40/60 mesh, Markers, USA) sorbent tubes. Tenax-TA sorbent tubes were conditioned for 6 h at 300 \u0026deg;C using TC-20 (Markers, USA) prior to measurement (Supplementary Table 1). Sampling of VOCs was conducted for 5 min during the painting and drying operations with a flow rate of 100 ml/min with sorbent tubes filled with Tenax-TA. The flow rate of the sampling pump equipped with the sorbent tube was corrected using a soap film flowmeter before starting measurements. Tenax-TA sorbent tubes were refrigerated at 4 \u0026deg;C or below and analyzed using gas chromatography\u0026ndash;mass spectrometry GC/MS (Agilent Technologies, Inc., Agilent HP-6890, USA) (Table S1). As standard substances of the VOCs to be analyzed, 10 CHEM, 50 ozone precursors, and TO-14 of Supelco containing 42 toxic VOCs were used (Table S2). Out of a total of 102 chemicals, 88 were classified by excluding overlapping substances in these standard categories (Table S2). GC/MS analysis was performed using secondary thermal desorption and solvent delay for 5 min to minimize the analysis of the initial low molecular weight material, maintaining a temperature of 50 \u0026deg;C for 10 min, and gradually increasing the temperature to 220 \u0026deg;C. After maintaining the temperature at 220 \u0026deg;C for 10 min, the post run was set to 5 min to reduce the contamination of equipment due to the inflow of polymers other than the compounds to be measured. The analysis of each sample took approximately 54 min.\u003c/p\u003e\n\u003cp\u003eThe linearity of the measured VOCs was evaluated using 100 \u0026mu;g/ml of a liquid standard substance (Supelco, USA), which was added in quantities of 100, 300, and 500 ng concentrations into three Tenax-TA sorbent tubes through the adsorbent tube injector system. Based on the linearity evaluation of the calibration curve, the coefficient of determination (R\u003csup\u003e2\u003c/sup\u003e) was 0.99 or higher and the relative standard deviation, which represents the reproducibility of the analysis, was evaluated at 0.52 to 4.32%.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3. Calculation of removal efficiency\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTHC\u0026nbsp;removal\u0026nbsp;efficiency of the adsorption system\u0026nbsp;was calculated using\u0026nbsp;equations (1) \u0026ndash;(3).\u0026nbsp;For the average concentrations of the inlet\u0026nbsp;and outlet, flow rate (m\u003csup\u003e3\u003c/sup\u003e/min) and THC concentration (ppm)) were multiplied and divided by the sum of the total flow rate (m\u003csup\u003e3\u003c/sup\u003e/min)\u0026nbsp;for\u0026nbsp;all\u0026nbsp;operations in (1) and (2).\u0026nbsp;The total removal\u0026nbsp;efficiency of the adsorption system was calculated using the difference of the average concentrations of the inlet and outlet divided by average inlet concentration in (3).\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003eVOC species\u0026nbsp;removal\u0026nbsp;efficiency of the adsorption system\u0026nbsp;at the outlet was calculated using\u0026nbsp;equation (4).\u0026nbsp;VOC species removal\u0026nbsp;efficiency for each species was calculated using the difference of the average concentrations at the inlet and outlet divided by the inlet concentration (4).\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e3.1 Comparison of old and new adsorption systems\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformation on the volume of the adsorption system, area of cartridge, number of cartridges, total area, thickness, volume, and quantity of activated carbon at each auto-repair shop are summarized in Table 2. All the three auto-repair shops used activated carbon cartridges to remove the THC emitted from the processes. For Old 1, the maintenance and control status of the equipped activated carbon was insufficient to remove the emitted pollutants. Especially, for Old 1, the quantity of activated carbon was 120 kg, which is the lowest compared to New 1 and 2 (510 and 340 kg, respectively). In addition, the thickness of activated carbon filter, area, and volume were low in all three shops, indicating poor maintenance and control including lack of regular checking of adsorption efficiency and replacement of activated carbon.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e Information on adsorption systems of the three auto-repair shops\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" width=\"7.436708860759493%\"\u003e\u003cstrong\u003eAuto-repair shops\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"3\" width=\"16.29746835443038%\"\u003e\u003cstrong\u003eVolume of adsorption system (W \u0026times; L \u0026times; H) (m)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"6\" width=\"76.26582278481013%\"\u003e\u003cstrong\u003eActivated carbon\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"23.443983402489625%\"\u003e\u003cstrong\u003eArea of cartridge\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"17.634854771784234%\"\u003e\u003cstrong\u003eNumber of Cartridges\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.42738589211618%\"\u003e\u003cstrong\u003eTotal area\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.692946058091286%\"\u003e\u003cstrong\u003eThickness\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.560165975103734%\"\u003e\u003cstrong\u003eVolume\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"12.240663900414937%\"\u003e\u003cstrong\u003eQuantity\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"28.463476070528966%\"\u003e\u003cstrong\u003e(m\u003c/strong\u003e\u003cstrong\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"21.15869017632242%\"\u003e\u003cstrong\u003e(m\u003c/strong\u003e\u003cstrong\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.624685138539043%\"\u003e\u003cstrong\u003e(mm)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.89168765743073%\"\u003e\u003cstrong\u003e(m\u003csup\u003e3\u003c/sup\u003e)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.861460957178842%\"\u003e\u003cstrong\u003e(kg)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"7.436708860759493%\"\u003eOld 1 (1\u0026nbsp;and\u0026nbsp;2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.29746835443038%\"\u003e2.0 \u0026times; 1.6 \u0026times; 2.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.879746835443036%\"\u003e1.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.449367088607595%\"\u003e4\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.291139240506329%\"\u003e4.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"10.443037974683545%\"\u003e50\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"11.867088607594937%\"\u003e0.24\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"9.335443037974683%\"\u003e120\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"7.436708860759493%\"\u003eNew 1 (1 and 2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.29746835443038%\"\u003e2.0 \u0026times; 2.0 \u0026times; 2.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.879746835443036%\"\u003e2.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.449367088607595%\"\u003e4\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.291139240506329%\"\u003e10.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"10.443037974683545%\"\u003e100\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"11.867088607594937%\"\u003e1.02\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"9.335443037974683%\"\u003e510\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"7.436708860759493%\"\u003eNew 2 (1 and 2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.29746835443038%\"\u003e2.0 \u0026times; 1.5 \u0026times; 3.0\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"17.879746835443036%\"\u003e1.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.449367088607595%\"\u003e6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"13.291139240506329%\"\u003e7.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"10.443037974683545%\"\u003e90\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"11.867088607594937%\"\u003e0.68\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"9.335443037974683%\"\u003e340\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFlow rates of adsorption systems were measured during painting and drying operations (Table 3). Overall, the measured flow rates of adsorption systems of all three auto-repair shops were considerably different compared to that of their designs. The designed flow rate of the three shops was 380\u0026ndash;400\u0026nbsp;S m\u003csup\u003e3\u003c/sup\u003e/min to remove pollutants; however, the actual flow rates were 2.3\u0026ndash;22.2% of their design flow rates (Old 1-1: 18.9%, Old 1-2: 14.9%, New 1-1: 2.3%, New 1-2: 3.0%, New 2-1: 22.2%, and New 2-2: 11.4%). Insufficient quantity and irregular replacement of activated carbon and maintaining a low flow rate during operations can lead to the detachment of the adsorbent or in decreased adsorption efficiency (Song and Chun 2021).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e Flow rates of adsorption systems of the three auto-repair shops\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" width=\"13.067150635208712%\"\u003e\u003cstrong\u003eAuto-repair shops\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"21.77858439201452%\"\u003e\u003cstrong\u003eDesign flow rate\u0026nbsp;\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"3\" width=\"65.15426497277677%\"\u003e\u003cstrong\u003eMeasured flow rate\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"33.70473537604457%\"\u003e\u003cstrong\u003ePaint\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"38.16155988857939%\"\u003e\u003cstrong\u003eDry\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.133704735376046%\"\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.052192066805844%\"\u003e(S m\u003csup\u003e3\u003c/sup\u003e/min)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"25.260960334029228%\"\u003e(S m\u003csup\u003e3\u003c/sup\u003e/min)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.60125260960334%\"\u003e(S m\u003csup\u003e3\u003c/sup\u003e/min)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"21.085594989561585%\"\u003e(S m\u003csup\u003e3\u003c/sup\u003e/min)\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.067150635208712%\"\u003eOld 1 (1-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"21.77858439201452%\"\u003e380\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"21.960072595281307%\"\u003e208.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"24.86388384754991%\"\u003e12.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.330308529945555%\"\u003e71.7\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.705336426914155%\"\u003eOld 1 (1-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.074245939675173%\"\u003e187.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"31.786542923433874%\"\u003e11.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"23.4338747099768%\"\u003e56.8\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.067150635208712%\"\u003eNew 1 (1-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"21.77858439201452%\"\u003e400\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"21.960072595281307%\"\u003e35.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"24.86388384754991%\"\u003e2.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.330308529945555%\"\u003e9.1\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.705336426914155%\"\u003eNew 1 (1-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.074245939675173%\"\u003e39.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"31.786542923433874%\"\u003e6.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"23.4338747099768%\"\u003e12.0\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.067150635208712%\"\u003eNew 2 (2-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"21.77858439201452%\"\u003e380\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"21.960072595281307%\"\u003e313.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"24.86388384754991%\"\u003e4.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.330308529945555%\"\u003e84.2\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.705336426914155%\"\u003eNew 2 (2-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"28.074245939675173%\"\u003e211.0\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"31.786542923433874%\"\u003e20.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"23.4338747099768%\"\u003e43.2\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e3.2. Emitted THC concentrations of old and new adsorption systems\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe emitted THC concentrations during auto-repair operations were measured using a portable FID detector. Figure 1 shows the variations in emission rates with time of the painting and drying operations of the three auto-repair shops. In all the auto-repair shops, the THC emission rates increased rapidly as the painting operation started and after peaking they decreased with regular fluctuations. The periodicity of the fluctuations in emission rates were different for the \u0026lsquo;Old\u0026rsquo; and \u0026lsquo;New\u0026rsquo; adsorption systems.\u003c/p\u003e\n\u003cp\u003eIn the case of Old 1-1, the fluctuation in the THC outlet concentration was higher than that of the inlet concentration. The THC concentration ranged from 2 to 248 ppm for the old adsorption system (Old 1) and it ranged from 0 to 496 ppm for the new adsorption system (New 1\u0026nbsp;and\u0026nbsp;2) for both inlets and outlets. In both adsorption systems, there was a delay between the THC inlet and outlet measurements. A peak in the THC concentration at the inlet was immediately followed by a peak at the outlet. The THC concentration at the outlet was higher than that at the inlet concentration in Old 1-1. In Old 1-1, 32 min after the start of the operation, the THC outlet concentration became higher than that of the inlet, and remained high.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;These reverse fluctuations indicate as follows: 1) The adsorption system did not work efficiently to reduce the emission of pollutants during the painting and drying operations; 2) Unremoved substances from the adsorption systems can disperse and affect the air quality of surrounding areas. Compared to Old 1, New 1 and 2 showed a stable fluctuation, that is, the THC concentrations of outlets were lower than that of inlets during operations. Therefore, the new adsorption systems effectively remove emitted pollutants.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe THC concentrations detected during the painting and drying operations at the inlets and outlets of the auto-repair shops are presented in Table 3. The total THC concentration ranged from 1.7\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e3\u003c/sup\u003e to 6.3 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e ppm for all auto-repair shops. For Old 1-1, the THC concentration at the outlet (5.4 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e ppm) was higher than that at the inlet (3.8 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e) for both operations. In other adsorption systems, the concentrations at the inlets (Old 1-2: 4.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 1-1: 1.2\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 1-2: 2.5\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 2-1: 6.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 2-2: 4.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e) were lower than those of the outlets (Old 1-2: 2.8\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 1-1: 1.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 1-2: 1.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 2-1: 4.1\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e, New 2-2: 2.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e) because the pollutants were removed and the THC concentration decreased.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3 THC removal efficiency of auto-repair operations\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"13.781512605042018%\"\u003e\u003cstrong\u003eAuto-repair shop\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e\u003cstrong\u003eOperation\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"15.798319327731093%\"\u003e\u003cstrong\u003eMeasurement location\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e\u003cstrong\u003eTotal THC concentration (ppm)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e\u003cstrong\u003eTotal flow rate (m\u003csup\u003e3\u003c/sup\u003e/min)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e\u003cstrong\u003eRemoval efficiency (%)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e\u003cstrong\u003eAverage THC concentration (ppm)\u003c/strong\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"28\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"NaN%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eOld 1 (1-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e3.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e11,242\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e\u0026minus;47.7\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e29.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"18\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e5.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e43.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e4.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e1,515\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e9.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e27.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e3.8\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e25.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e3.8\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e12,757\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e\u0026minus;41.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e28\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e5.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e31\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eOld 1 (1-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e4.2\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e8,064\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e39\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e49\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.6\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e30.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e1.9\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e1,419\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e\u0026minus;43.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e12.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.7\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e19.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e4.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e9,483\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e35.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e22.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.8\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e22.1\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eNew 1 (1-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e\n \u003col\u003e\n \u003cli\u003e\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e1,032\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e20.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e98\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e8.1\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e77.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e2.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e358\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e0.7\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e38.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e26.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e1.2\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e1,390\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e17.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e49.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e\n \u003col\u003e\n \u003cli\u003e\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003c/li\u003e\n \u003c/ol\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e36.1\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eNew 1 (1-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e2.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e4,588\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e66.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e204\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e6.7\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e68.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e5.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e795\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e29.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e43\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e3.5\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e23.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e2.5\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e5,382\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e59.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e70\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e1.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e31.5\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eNew 2 (2-1)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e6.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e13,487\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e34.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e45.9\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e4.1\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e30\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e3.8\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e3\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e566\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e55.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e11.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e1.7\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e3\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e3.6\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e6.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e14,053\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e35.1\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e20.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e4.1\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e10.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"6\" width=\"13.781512605042018%\"\u003eNew 2 (2-2)\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003ePainting\u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"15.798319327731093%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"14.117647058823529%\"\u003e3.9\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"13.949579831932773%\"\u003e3,586\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"14.117647058823529%\"\u003e48\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"14.117647058823529%\"\u003e108.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.0\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e56.2\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eDrying\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e4.1\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e2,507\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e10\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e16.7\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e3.7\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e4\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e3.3\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003eTotal\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"18.323586744639375%\"\u003eInlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"16.374269005847953%\"\u003e4.3\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.179337231968812%\"\u003e6,093\u003cbr\u003e\u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"16.374269005847953%\"\u003e44.4\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"16.374269005847953%\"\u003e27.8\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.87786259541985%\"\u003eOutlet\u003cbr\u003e\u003c/td\u003e\n \u003ctd width=\"32.06106870229008%\"\u003e2.4\u0026nbsp;\u0026times;\u0026nbsp;10\u003csup\u003e5\u003c/sup\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 12.7516%;\" width=\"32.06106870229008%\"\u003e9.7\u003cbr\u003e\u003c/td\u003e\n \u003ctd height=\"19\" style=\"width: 0.8054%;\" width=\"0%\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e3.3. THC removal efficiency\u003c/strong\u003e\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Table 3 shows the removal efficiencies of adsorption systems of the three auto-repair shops, which were calculated based on total flow rates and the total of inlet and outlet concentrations. The total THC emissions (ppm) in both operations were divided by total flow rate (m\u003csup\u003e3\u003c/sup\u003e/min) at each inlet and outlet.\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;For all auto-repair shops, the removal efficiency ranged from \u0026minus;41.3 to 59.2%. The order of removal efficiency for both operations in the three auto-repair shops was as follows: New 1-2 (59.2%) \u0026gt; New 2-2 (44.4%) \u0026gt; New 2-1 (35.1%) \u0026gt; Old 2 (35.4%) \u0026gt; New 1 (17.2%) \u0026gt; Old 1 (\u0026minus;41.3%). It has been reported that in same auto-repair shops, the removal efficiency was different because of multiple factors that affect adsorption efficiency such as quantity of paint used, operation time, and workers\u0026rsquo; characteristics (Wang et al. 2017).\u0026nbsp;\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;For Old 1-1, in the painting operation, the total THC concentration of the inlet was 3.4 \u0026times; 10\u003csup\u003e5\u0026nbsp;\u003c/sup\u003eppm and that of the outlet was 5.0 \u0026times; 10\u003csup\u003e5\u0026nbsp;\u003c/sup\u003eppm, which results in a removal efficiency of \u0026minus;47.7%. For Old 1-2, in the drying operation, the total THC concentration of the inlet was 1.9 \u0026times; 10\u003csup\u003e4\u0026nbsp;\u003c/sup\u003eppm and outlet was 2.7 \u0026times; 10\u003csup\u003e4\u0026nbsp;\u003c/sup\u003eppm, which results in a removal efficiency of \u0026minus;43.9%. In addition, for Old 1-1, in the painting operation, the average concentration of the inlet was 29.6 ppm and that of the outlet was 43.5 ppm, which is 1.47 times higher than that of the inlet. For Old 1-2, in the drying operation, the average concentration of the inlet was 12.9 ppm and that of the outlet was 19.2 ppm, which is 1.49 times higher than that of the inlet. This negative removal efficiency can be explained by three factors: 1) The flow rate of the adsorption system was not adequate to remove the chemicals emitted during operations (Noh et al. 2008). In the case of Old 1-2, the total flow rate decreased from 8,064 m\u003csup\u003e3\u003c/sup\u003e/min to 1,419 m\u003csup\u003e3\u003c/sup\u003e/min, and because of this rapid decrease in flow rate by 82.4%, the pollutants emitted during the painting and drying operations were adsorbed by the adsorbent; 2) The accumulated chemicals that were attached to the adsorbent in previous operations disrupted the removal process of the newly emitted chemicals. Except for New 2, in all other cases, water-based paint was used and oil-based paint was only used occasionally. The use of oil-based paints can result in higher concentrations of VOCs compared to the use of water-based paints (Song and Chun 2021); moreover, oil-based paints can lead to the accumulation of emitted pollutants, thereby affecting the adsorption process.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4. Removal efficiency of VOC species\u003c/strong\u003e\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Eighty-eight VOC species, including 5 CHEM, 33 TO-14, and 50 ozone precursor compounds, were analyzed. Analysis of the VOCs was performed by focusing on the dry phase, which is the endpoint of the operations. The concentrations of the top five species of VOCs are presented in Fig. 2 and Table S4. Removal efficiencies of the auto-repair shops are shown in Fig. 3. Detailed results are provided in Table S5. \u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; Based on the total concentration at the inlet and outlet in the dry phase, the top five VOCs were identified as butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene. These were also detected in many previous studies (Kim et al. 2020; Park et al. 2008). The inlet concentration of the top five VOC species for Old 1-1, Old 1-2, New 1-1, New 1-2, New 2-1, and New 2-2 were 45\u0026minus;1,231, 73\u0026minus;1,256 260\u0026minus;2,503, 587\u0026minus;2,997, 78\u0026minus;1,034, and 158\u0026minus;1,256 ppm, respectively. Comparatively, the inlet concentrations for Old 1-1, Old 1-2, New 1-1, New 1-2, New 2-1, and New 2-2 were 121\u0026minus;1,478, 135\u0026minus;2.465, 199\u0026minus;2,081, 288\u0026minus;2,338, 61\u0026minus;743, and 95\u0026minus;902 ppm, respectively. Overall, in the case of the old adsorption system, the outlet concentrations of the top five species were higher than those of the inlet. For New 1 and 2, which are equipped with the new adsorption systems, the outlet concentrations were lower than those of the inlet. \u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Figure 3 shows that the top five VOC species achieved a positive (+) removal efficiency at New 1\u0026ndash;2 while it was negative (\u0026minus;) at Old 1. The removal efficiencies of the top five VOC species ranged from \u0026minus;178.4 to \u0026minus;11.6% in Old 1-1 and \u0026minus;96.2 to \u0026minus;3.5% in Old 1-2. On the contrary, the removal efficiency of New 1 ranged from 5.8 to 65.3% and of New 2 ranged from 21.4 to 54.0%, indicating a high removal efficiency. It was estimated that the VOC compounds generated from former operations were desorbed during this measurement and the adsorbent (activated carbon) had a low adsorption capacity because of its irregular replacement.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp skip=\"true\"\u003eWe analyzed the removal efficiencies of THC and VOCs for old and new adsorption systems. We confirmed that the removal efficiency was high in the new adsorption system. Recently, the Korean government implemented a policy to support small-scale auto-repair shops by replacing their old adsorption systems with new adsorption systems. Therefore, our findings provide support to extend this program to improve the removal efficiencies of THC and VOCs that are emitted from auto-repair shops.\u0026nbsp;\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; The removal efficiencies of THC and VOC species were the highest in New 1\u0026ndash;2. Contrastingly, in the old auto-repair shops, the removal efficiencies were negative (\u0026minus;) at \u0026minus;47.7% during the painting operation in Old 1-1 and \u0026minus;43.9% during the drying operation in Old 1-2. The removal efficiencies were negative for the top five VOC species in Old 1\u0026ndash;2, ranging from \u0026minus;178.4 to \u0026minus;3.5% and positive in New 1\u0026ndash;2 at 5.8\u0026ndash;65.3%. We confirmed the significance of replacing the adsorption system with the newly designed system that consists of increased quantity and thickness of activated carbon with a better replacement cycle to efficiently recover the VOCs emitted from the painting and drying operations. \u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp; To design an adsorption system with a high removal efficiency, it is necessary to consider the characteristics of commonly used paints including their contents of aromatic hydrocarbons, aliphatic hydrocarbons, esters, ketones, alcohols, and glycol ethers (Kim 2011). In our study, the top five VOCs were butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene, which are aromatic hydrocarbons. Aromatic hydrocarbons contribute significantly to the formation of ozone, other photooxidants, and secondary organic aerosols in urban atmospheres (Luo et al. 2021). Therefore, when choosing the adsorbent or activated carbon in the adsorption system, it is necessary to consider the characteristics of VOCs.\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Moreover, there is need to manage and control the main operations that produce high VOCs emissions. In a previous study on auto-assembly plants, spray painting (primers and top coats) were the major sources of VOCs and about 70\u0026ndash;80% of the VOCs were generated from the spray booth (Chang et al. 2002). Therefore, during the spraying operation, the management should focus on providing an adequate flow rate to facilitate the capture of VOCs through regular and timely replacement of cartridges and check the breakthrough (saturation) point of the activated carbon frequently. \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp skip=\"true\"\u003eThe trends of THC emitted from old and new adsorption systems of auto-repair shops in Korea were identified. In the old adsorption system, reverse fluctuation was observed wherein the THC concentration at the outlet was higher than that of the inlet. We compared the removal efficiencies of emitted THC and VOCs of the old and new adsorption systems. The removal efficiency of the new adsorption system was 17.2\u0026ndash;59.2% and that of the old adsorption system was \u0026minus;41.3\u0026ndash;35.4%. The top five VOCs that were captured at the outlet were butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene, which are aromatic hydrocarbons. In particular, for each VOC species, The removal efficiencies for the top five VOCs were positive (+) in the new adsorption system and negative (\u0026minus;) in the old adsorption system.\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Our findings provide a scientific basis for implementing appropriate control and effective management of adsorption systems in auto-repair shops to efficiently remove emitted VOCs from painting and drying operations. In addition, our study can lead to improvements in implementing policies that provide installation support for small businesses toward achieving a better VOC removal efficiency in the future.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by the Seoul Institute of Technology (SIT) (2021-AE-002)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Haejoon Chun and Min Young Song. The first draft of the manuscript was written by Haejoon Chun and Min Young Song and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data are provided in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAfshari A, Lundgren B,Ekberg L E (2003) Comparison of three small chamber test methods for the measurement of VOC emission rates from paint. 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Atmospheric Environment 150:116\u0026ndash;125. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://dx.doi.org/10.1016/j.atmosenv.2016.11.023\u003c/span\u003e\u003cspan address=\"10.1016/j.atmosenv.2016.11.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"adsorption system, automotive painting, removal efficiency, total hydrocarbon removal, volatile organic compound species ","lastPublishedDoi":"10.21203/rs.3.rs-2102515/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2102515/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTotal hydrocarbon (THC), including volatile organic compounds (VOCs), is emitted during the operations of an auto-repair painting workshop. VOCs are especially hazardous pollutants because of their impacts on ozone formation and human health. To reduce the THC generated from small auto-repair painting shops, the Korean government conducts a support program to enable them to shift from an old to a new adsorption system. Although lab-scale evaluations of the pollutant reduction efficiencies of some adsorption devices have been carried out, actual field evaluations are lacking. In this study, three auto-repair shops (one with an old and two with new air pollutant adsorption systems) in Seoul were selected to evaluate their removal efficiencies with respect to THC and VOCs during painting and drying operations. Results show that the THC removal efficiencies were \u0026minus;\u0026thinsp;41.3\u0026ndash;35.4% and 17.2\u0026thinsp;\u0026minus;\u0026thinsp;59.2% for the old and new adsorption systems, respectively. The removal efficiencies of the top five VOC species such as butyl acetate, toluene, 1,2,3-trimethylbenzene, m,p-xylene, and ethylbenzene were positive (+) and negative (\u0026minus;) for the new and old adsorption systems, respectively. These results provide a theoretical basis that endorses the government support policy for the removal of air pollutants from the emissions of small businesses that are not well managed, such as auto-repair painting, printing, and dry cleaning.\u003c/p\u003e","manuscriptTitle":"Removal efficiencies of emissions of volatile organic compounds by adsorption systems installed in small-scale auto-repair painting operations","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-09-29 14:42:10","doi":"10.21203/rs.3.rs-2102515/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ee767a4b-086d-4ffc-80e3-947c5eb4f475","owner":[],"postedDate":"September 29th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-10-11T19:29:19+00:00","versionOfRecord":[],"versionCreatedAt":"2022-09-29 14:42:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2102515","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2102515","identity":"rs-2102515","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}