• 환경위생공학
• /
• 제17권1호
• /
• pp.12-19
• /
• 2002

This study was carried out to investigate the optimal condition for granite particle coagulation process by using various chemical coagulation agents. The coagulation of a suspended granite particle was monitored by using various different coagulants, such as $Al_2(SO_4)_3{\cdot}14H_2O,{\;}FeCl_3{\cdot}6H_2O,{\;}SA-solution(KOH{\;}+{\;}Al(OH)_3{\;}+{\;}K_2CO_3{\;}mixture)$ and jade particle. To accomplish this study, analysis of water quality, removing Turbidity and Packing Density were measured with jar-tester. In the results of this experiment, it was found that the removal rate of the granite particle was increased with the decrease of the pH of the sludge. The turbidity(NTU) at the above coagulants was reduced from 95% to 98%. Removed of Turbidity and Packing Density was more efficiency to the SA-solution than others.

• 상하수도학회지
• /
• 제18권5호
• /
• pp.689-695
• /
• 2004

Electrocoagulation has been suggested as a promising alternative to conventional coagulation. The process is characterized by reduced sludge production, no requirement for chemical use, and ease of operation. However, this coagulation has scarcely been studied in water purifying process. This study was performed several batch experiments to compare turbidity removal between electrocoagulation and chemical coagulation. In addition, characteristics of floe were evaluated with zeta potential and particle size distributions. Electrocoagulation showed a relatively higher removal of turbidity (approximately 5%) with the same aluminum amount than conventional chemical coagulation. In addition, turbidity removal by electrocoagulation was less sensitive to pH and was greater for more extensive pH range than chemical coagulation. The results of zeta potential and floc size distributions illustrated that electrocoagulation provided the preferable conditions for coagulation such as zeta potential close to zero millivolt and increased portions of particles in the range of 40 and $100{\mu}m$.

• 대한기계학회논문집A
• /
• 제33권10호
• /
• pp.1023-1028
• /
• 2009

Cleaning is required following CMP (chemical mechanical planarization) to remove particles. The minimization of particle residue is required with each successive technology generation, and the cleaning of wafers becomes more complicated. In copper damascene process for interconnection structure, it utilizes 2-step CMP consists of Cu and barrier CMP. Such a 2-steps CMP process leaves a lot of abrasive particles on the wafer surface, cleaning is required to remove abrasive particles. In this study, the chemical mechanical cleaning(CMC) is performed various conditions as a cleaning process. The CMC process combined mechanical cleaning by friction between a wafer and a pad and chemical cleaning by CMC solution consists of tetramethyl ammonium hydroxide (TMAH) / benzotriazole (BTA). This paper studies the removal of abrasive on the Cu wafer and the cleaning efficiency of CMC process.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.743-746
• /
• 2000

The removal of contaminants of silicon wafers has been investigated by various methods. Laser cleaning is the new dry cleaning technique to replace wafer wet cleaning in the near future. A dry laser cleaning uses inert gas jet to remove contaminant particles lifted off by the action of a KrF excimer laser. A laser cleaning model is developed to simulate the cleaning process and analyze the influence of contaminant particles and experimental parameters on laser cleaning efficiency. The model demonstrates that various types of submicrometer-sized particles from the front sides of silicon wafer can be efficiently removed by laser cleaning. The laser cleaning is explained by a particle adhesion model. including van der Waals forces and hydrogen bonding, and a particle removal model involving rapid thermal expansion of the substrate due to the thermoelastic effect. In addition, the experiment of wafer laser cleaning using KrF excimer laser was conducted to remove various contaminant particles.

• 한국물환경학회지
• /
• 제24권4호
• /
• pp.415-422
• /
• 2008

Drinking water treatment is enhanced by coagulant dosages and chlorine injection because of pH increase in raw water in droughty seasons such as spring and fall. But water quality deterioration is occurred by increase in residual aluminium and disinfection by-products. Coagulation process can be used to control natural organic matter (NOM) during water treatment. The effect of coagulation process appeared to depend on the pH of water rather than coagulant dosages. In this study, for water treatment in high pH season $H_2SO_4$ was applied for pH adjustment at full scale. Before and after pH adjustment by $H_2SO_4$ injection, water quality of drinking water was evaluate. In the result of investigation of total organic carbon (TOC) removal in high pH season, TOC was removed approximately 30~40%, which showed decrease in water treatment efficiency. Also, it is increased both particle numbers and residual Al concentration in the water. After $H_2SO_4$ injection for adjustment to pH<7.5 in settled water, treated water turbidity decreased in 0.047 NTU from 0.059 NTU, and particle numbers of filtered water decreased in 20/mL from 90/mL. On the other side, TOC removal efficiency increased in approximately 10% after adjustment of pH. In the result of decrease in pH in raw water through more coagulants and prechlorine without $H_2SO_4$ injection, trihalomethanes (THMs) concentration increased in $16{\mu}g/L$ from $8{\mu}g/L$.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제18권7호
• /
• pp.1-11
• /
• 2013

The actively soil pollution by the toxic heavy-metals like the arsenic, cadmium, lead due to the industrialization and economic activity. The uses the electrokinetic remediation of contaminated soil has many researches against the fine soil having a small size in the on going. However, it is the actual condition which the research result that is not effective due to the low surface charge of the particle and high permeability shows in the electrokinetic remediation in comparison with the fine soil in the case of the sandy soil in which the particle size is large. In this research, the electrokinetic remediation and ultrasonic wave fetch strategy is compound applied against the sandy soil polluted by the arsenic, cadmium, and lead removal efficiency of the sandy soil through the comparison with the existing electrokinetic remediation tries to be evaluated. First of all, desorption of contaminants in soil by ultrasonic extraction in the Pre-Test conducted to see desorption effective 5~15%. After that, By conducted Batch-Test results frequency output century 200 Khz, reaction time 30 min, contaminated soil used in experiment was 500 g. Removal efficiency of arsenic, cadmium, lead are 25.55%, 8.01%, 34.90%. But, As, Cd, Pb remediation efficiency less than 1% in EK1(control group).

• 한국물환경학회지
• /
• 제37권1호
• /
• pp.10-19
• /
• 2021

In the flotation process to remove microplastic (MP) particles, the attachment and separation efficiency is determined by the basic physicochemical characteristics of MP particles as well as bubbles. To evaluate the flotation characteristics of MP particles, we carried out a series of simulations using the population balance (PB) model. The initial attachment coefficient (αo) of MP particles was in the range of 0.2-0.275, and it was slightly lower than that of typical particles, such as clay, debris and algae particles, which exist in water bodies, αo, 0.3-0.4. The relative bubble number (RBN) attached to the surface of the typical number of bubbles was 0.30 and 0.32 for MP 30 ㎛ and MP 58 ㎛, respectively. In comparison, the RBN of larger MP particles (138 ㎛) was as high as 0.53. Furthermore, smaller microbubbles were required to separate properly or additional treatment needed to be applied to enhance collision and attachment efficiency since the flotation of MP particles was found to be difficult to treat as high-rate. As a result of comparing the removal rate (experimental value) of MP particles obtained from the batch-type flotation apparatus and the flotation removal rate (predicted value) of MP obtained through the PB model, the final particles by the particle size of MP overall except for the initial separation time area. With respect to the removal efficiency, the observed and predicted values were similar, and it was confirmed that the floating separation characteristics and evaluation of the MP particles through the PB model could be possible.

• 한국입자에어로졸학회지
• /
• 제17권4호
• /
• pp.115-123
• /
• 2021

The emission gas from meat grilled restaurants has unpleasant odor and sticky particulate matters (PM) in form of oil mist. This affects the residents living nearby. In oder to decrease the odor and PM, electrostatic precipitators (ESP) were installed at several restaurants by support of Seoul metropolitan government and emission characteristics of PM and odor were investigated. The removal efficiency of odor and PM at before- and after-ESP was that total hydrocarbon (THC), NH₃, H₂S, acetaldehyde, butyraldehyde were not much decreased. Total suspended particles (TSP) emitted from the vent was below the value of 7 mg/m³ regardless of the concentration of before-ESP and removal efficiency was in the range of 64 ~ 86%. The ratio of PM_1.0 to PM₁₀ of emission gas was over 0.9. So it was revealed that most PM of emission gas was PM1.0. The PM concentration in the air of the street near the vent was higher than another street due to the emission gas and the PM of indoor air of restaurant grilling meats was measured very high compared to outdoor air. So it needs more powerful ventilation of indoor air.

• 대한환경공학회지
• /
• 제37권1호
• /
• pp.7-13
• /
• 2015

본 연구에서는 맛 냄새 물질 발생시 표준정수처리공정에서 지오스민과 활성탄 주입량을 효과적으로 저감하는 방안을 제시하였다. 염소처리방식에 따른 지오스민 제거효율을 평가한 결과, 저농도(< 25 ng/L)의 경우 전염소와 중간염소를 동시에 운영할 경우 지오스민 제거율은 46%인 반면, 중간염소로 운영한 공정의 지오스민 제거율은 57%로 나타났다. 중농도(25~79 ng/L)에서는 전염소와 중간염소로 운영한 지오스민 제거율은 59%, 중간염소로 운영한 지오스민 제거율은 87%로 나타났다. 고농도(> 80 ng/L)에서도 전염소와 중간염소를 동시에 운영한 지오스민 제거율은 67%인 반면 중간염소로 운영한 지오스민 제거율은 95%로 나타나 중간염소로 운영시 제거율이 높아지는 것으로 나타났다. 지오스민 농도별 측정결과와 활성탄 투입량의 상관성을 분석한 결과, 결정계수($R^2$)는 0.96 으로 나타나 적합한 분말활성탄 조견표를 제안하였다. 또한, 지오스민 물질발생 초기에 중간염소와 활성탄을 동시에 투입 시 원수농도가 급격히 증가하여도 지오스민의 입자성 물질을 지속적으로 제거할 수 있어 활성탄 저감 뿐만 아니라 정수 기대농도도 만족할 수 있었다.

• 상하수도학회지
• /
• 제20권3호
• /
• pp.367-375
• /
• 2006

Sequencing Batch Reactor (SBR) is well adopted for community wastewater treatment for its simplicity, performance and various advantageous treatment options. SBR is now drawing attention for its process modification such as coupled with membrane bioreactor, reverse osmosis or applying different media to achieve high removal efficiency. This study focused on the improved efficiency of carbon, nitrogen and phosphorous removal by applying zeolite materials called bioceramics to the SBR. Two laboratory-scale SBR units were operated in the same operating conditions - one with bioceramics called Bioceramic SBR (BCSBR) and the other without bioceramics used as control. Routine monitoring of COD, TP, $NH_3-N$, $NO_3-N$ was performed throughout this study. COD removal was about 80% to 100% and phosphorous removal was about 60% in the process whereas $NH_3-N$ removal efficiency was found to be 99.9% in the BCSBR unit. Addition of bioceramics also improved sludge characteristics such as sludge dewaterability, specific gravity and particle size. BCSBR can withstand high ammonia shock loading leading to the better treatment capacity of high ammonia containing wastewater. The cause of improved removal efficiencies within the biological reactor could be attributed to the biochemosorption mechanisms of bioceramics. Absorption/adsorption or desorption capacity of bioceramics was tested through laboratory experiments.