• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.744-751
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• 2007

Wet scrubber is widely used to remove toxic gaseous contaminants in various industries such as semi-conductor industry, display manufacturing industry and so on. In this study, to optimize a packed bed scrubber as one of typical wet scrubber size while keeping its performance, four different packing materials were investigated at different air flow rates, liquid-gas ratios and pH values. Ammonia, hydrochloric acid and hydrofluoric acid were used as test gases to characterize the scrubber performance. Gas removal efficiency increased as the packing size decreased, which resulted in the increase of specific surface area. The increase of air flow rate led to the decrease of gas removal efficiency, while the increase of liquid-gas ratio led to the increase of gas removal efficiency. For the case of $NH_3$ gas, lower pH, and for the cases of HCl and HF, higher pH contributed to higher gas removal efficiency. Gas removal efficiency of a wet scrubber increased in the order of HCl < $NH_3$ < HF according to its water solubility.

• Membrane and Water Treatment
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• v.13 no.1
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• pp.1-6
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• 2022

The regulations of the International Maritime Organization (IMO) have been steadily strengthened in ship emissions. Accordingly, there is a growing need for development of related technologies for the removal of contaminants that may occur during the treatment of SOx and NOx using a wet scrubber. However, this system also leads to wastewater production when the exhaust gas is scrubbed. In this research, we evaluated the performance of an ion selective resin process in accordance with scrubber wastewater discharge regulations, specifically nitrate discharge, by the IMO. Accelerated real and synthetic wastewater of wet scrubbers, contained high amounts of TDS with high nitrate, is used as feed water in lab scale systems. Furthermore, a pilot scale dissolved air flotation (DAF) using microbubble generator with ion exchange resin process was combined and developed in order to apply for the treatment of wet scrubber wastewater. The results of the present study revealed that operating conditions, such as resin property, bed volume (BV), and inlet wastewater flow rate, significantly affect the removal performance. Finally, through a pilot test, DAF with ion exchange resin process showed a noticeable improvement of the nitrate removal rate compared to the single DAF process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.88-89
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• 2009

In this paper, we investigated about wet cleaning effect as deep trench formation methods for Power chip devices. Deep trench structure was classified by two methods, PSU (Poly Stick Up) and Non-PSU structure. In this paper, we could remove residue defect during wet. cleaning after deep trench etch process for non-PSU structure device as to change wet cleaning process condition. V-SEM result showed void image at the trench bottom site due to residue defect and residue component was oxide by EDS analysis. In order to find the reason of happening residue defect, we experimented about various process conditions. So, defect source was that oxide film was re-deposited at trench bottom by changed to hydrophobic property at substrate during hard mask removal process. Therefore, in order to removal residue defect, we added in-situ SCI during hard mask removal process, and defect was removed perfectly. And WLR (Wafer Level Reliability) test result was no difference between normal and optimized process condition.

• Journal of environmental and Sanitary engineering
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• v.18 no.2
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• pp.87-93
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• 2003

This study carried out to recommend adaptable technologies and countermeasures for performance improvement of Wet Scrubber(WS) in industrial waste incinerator. When not using the Activated Carbon(AC), the removal efficiency of dust and HCl is 73%, 92%. And particulate phase and gaseous phase dioxins removal efficiency was evaluated up to 31% and 12%. In this case, dioxins enrichment was not revealed in WS. When using the AC mixing with scrubbing water, the case of 1,000ppm, removal efficiency of particulate phase dioxins was about 51%, and gaseous phase dioxins was about 96%. The case of 2,000ppm, removal efficiency of particulate phase dioxins was about 55%, and gaseous phase dioxins was about 97%. And the case of 3,500ppm, the removal efficiency of particulate phase dioxins was about 35%, and gaseous phase dioxins was about 96% respectively. By this study, using the AC was more useful to remove the gaseous phase dioxins, and needed to use proper concentration of the AC, that in case of 3,500ppm, the particulate phase dioxins removal efficiency was more lower than other cases.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1309-1313
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• 2003

This study was carried out to obtain the optimal ammonia removal efficiency using pyroligenous liquid for the economical and environment-friendly odor removal at a petty livestock farmhouse. The ammonia removal efficiencies were evaluated due to changing dilution rates(${\times}$10, ${\times}$20, ${\times}$30, ${\times}$50 and ${\times}$100 times) and different spray amounts(10$m\ell$ and 20$m\ell$) of pyroligenous liquid. The wet scrubber device was used to remove odor in closed-type livestock farmhouse. According to dilution rate of the pyroligenous liquid, the optimum rate was 20 times and the removal efficiency increased by decreasing dilution rates. In the case of spray amounts with the optimum dilution, the amount was 20 me and the removal efficiency increased by increasing spray amount. Also, the removal efficiency by using wet deodorizing device was 83.0-97.0％ with 20 times diluted liquid.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.842-845
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• 2011

Wet air oxidation (WAO) of oily sludge was carried out using $Fe^{3+}$ as catalyst, placed in a 0.5 L batch autoclave in the temperature range of $250-330^{\circ}C$. Experiments were conducted to investigate the effects of temperature, the initial COD, reaction time, concentration of catalyst and $O_2$ excess (OE) on the oxidation of the oily sludge. The results showed that in the WAO 88.4% COD was achieved after 9 min reaction at temperature of $330^{\circ}C$, OE of 0.8 and the initial COD of 20000 mg/L. Temperature was found to have a significant impact on the oxidation of oily sludge. Adding a catalyst significantly improved the COD removal. Homogenous catalyst, $Fe^{3+}$, showed effective removal for pollutants. COD removal was 99.7% in the catalytic wet air oxidation (CWAO) over $Fe^{3+}$ catalyst. The results proved that the CWAO was an effective pretreatment method for the oily sludge.

• Journal of the Korean Chemical Society
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• v.58 no.1
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• pp.68-71
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• 2014

Petroleum refining unavoidably generates large volumes of oily wastewater. The environmentally acceptable disposal of oily wastewater is a current challenge to the petroleum industry. Nowadays, more attentions have been focused on the treatment techniques of oily wastewater. Oily wastewater contained highly concentrated and toxic organic compounds. Wet peroxide oxidation (WPO) and catalytic wet oxidation (CWO) were applied to eliminate pollutants to examine the feasibility of the WPO/CWO of oily wastewater. The results indicated that more than 80% chemical oxygen demand (COD) removal from oily wastewater was achieved with CWO. Homogenous catalyst, $NaHCO_3$ and $Na_2CO_3$ and NaOH showed effective removal for pollutants in oily wastewater. Greater than 90% COD removal was achieved with WPO. It was concluded that WPO was a far more effective process for oily wastewater.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.9
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• pp.745-752
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• 2006

DOS and NaCl aerosol particles were used to determine collection efficiencies of a 2-stage electrostatic wet scrubber with respect to particle size. The DOS and NaCl aerosols have geometric mean diameters of 0.1-3.0 urn, geometric standard deviations of $1.1{\sim}1.8$ and total number concentrations of $450{\sim}2,400\;particles/cm^3$. The tested operating variables for the electrostatic wet scrubber included air velocity and water injection rate. It was shown from the experimental results that particle collection efficiencies increased in the submicron particle size range when different polarities were applied on the water nozzle and corona wire, respectively. This increase in the collection efficiency is attributed to strong electrostatic attraction between the negative water droplets and positive submicron particles. The collection efficiencies also increased when water injection rate was increased or air velocity was decreased. Meanwhile, the pressure drop across the wet scrubber decreased by 90% compared with the existing mechanical wet scrubber. Finally, ammonia gas was used to determine gas removal efficiencies. It was observed that the gas removal efficiencies increased when the air velocity was decreased or the water injection rate was increased.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.360-369
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• 2016

In this study, sequential leaching and wet torrefaction were performed to improve the fuel characteristics of empty fruit bunch (EFB). Leaching was carried out at $25{\sim}90^{\circ}C$ for 5~30 min. The highest ash removal efficiency of 55.99% was achieved when leaching was performed at $90^{\circ}C$ for 10 min. The ash removal efficiency was dependent more on leaching temperature than time. Wet torrefaction was carried out at $180{\sim}200^{\circ}C$ for 5~40 min, following the leaching. Most of the inorganic compounds were removed at removal efficiencies of 41.05~63.58% during sequential leaching and wet torrefaction, while silica remained in the biomass. Chloride, calcium, magnesium, and phosphorus showed more than 80% removal efficiencies. The calorific value of EFB increased to 7.96% (4730 kcal/kg) in comparison to the raw material (4390 kcal/kg) when wet torrefaction was performed at $200^{\circ}C$ for 40 min following leaching.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.935-938
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• 1997

Recently, the minimum line width shows a tendency to decrease and the multi-level increase in semiconductor. Therefore, a planarization technique is needed and chemical mechanical polishing(CMP) is considered as one of the most suitable process. CMP accomplishes a high polishing performance and a global planarization of high quality. But there are several defects in CMP such as micro-scratches, abrasive contaminations, and non-uniformity of polished wafer edges. Wet etching include of Spin-etching can improve he defects of CMP. It uses abrasive-free chemical solution instead of slurry. On this study, ILD(INterlayer-Dielectric) was removed by CMP and wet-etching methods in order to investigate the superiority of wet etching mechanism. In the thin film wafer, the results were evaluated at a viewpoint of material removal rate(MRR) and within wafer non-uniformity(WIWNU). And pattern step height was also compared for planarization characteristics of the patterned wafer.