Conventional wastewater treatment plants (WWTPs) do not fully remove micropollutants. Enhanced treatment of sewage effluents is being considered or implemented in some countries to minimize the discharge of problematic micropollutants from WWTPs. Representative enhanced sewage treatment technologies for micropollutant removal were reviewed, including their current status of research and development. Advanced oxidation processes (AOPs) such as ozonation and UV/H2O2 and adsorption processes using powdered (PAC) and granular activated carbon (GAC) were mainly discussed with focusing on process principles for the micropollutant removal, effect of process operation and water matrix factors, and technical and economic feasibility. Pilot- and full-scale studies have shown that ozonation, PAC, and GAC can achieve significant elimination of various micropollutants at economically feasible costs(0.16-0.29 €/m3). Considering the current status of domestic WWTPs, ozonation and PAC were found to be the most feasible options for the enhanced sewage effluent treatment. Although ozonation and PAC are all mature technologies, a range of technical aspects should be considered for their successful application, such as energy consumption, CO2 emission, byproduct or waste generation, and ease of system construction/operation/maintenance. More feasibility studies considering domestic wastewater characteristics and WWTP conditions are required to apply ozonation or PAC/GAC adsorption process to enhance sewage effluent treatment in Korea.

Industrial wastewater often contains a number of recalcitrant organic contaminants. These contaminants are hardly degradable by biological wastewater treatment processes, which requires a more powerful treatment method based on chemical oxidation. Advanced oxidation technology (AOT) has been extensively studied for the treatment of nonbiodegradable organics in water and wastewater. Among different AOTs developed up to date, ozonation and the Fenton process are the representative technologies that widely used in the field. Based on the traditional ozonation and the Fenton process, several modified processes have been also developed to accelerate the production of reactive radicals. This article reviews the chemistry of ozonation and the Fenton process as well as the cases of application of these two AOTs to industrial wastewater treatment. In addition, research needs to improve the cost efficiency of ozonation and the Fenton process were discussed.

In the present work, a new hydrogen added argon heat treatment process that prevents the formation of hydrides and eliminates the dehydrogenation step, is developed. Dissolved hydrogen has a good effect on sintering properties such as oxidation resistance and density of greens. This process can also reduce costs and processing time. In the experiment, commercially available Ti-6Al-4V powders are used. The powders are annealed using tube furnace in an argon atmosphere at 700oC and 900oC for 120 min. Hydrogen was injected temporarily during argon annealing to dissolve hydrogen, and a dehydrogenation process was performed simultaneously under an argon-only atmosphere. Without hydride formation, hydrogen was dissolved in the Ti-6Al-4V powder by X-ray diffraction and gas analysis. Hydrogen is first solubilized on the beta phase and expanded the beta phases’ cell volume. TGA analysis was carried out to evaluate the oxidation resistance, and it is confirmed that hydrogen-dissolved Ti-6Al-4V powders improves oxidation resistance more than raw materials.

Volatile organic compounds(VOCs) are toxic carcinogenic compounds found in wastewater. VOCs require rapid removal because they are easily volatilized during wastewater treatment. Electrochemical advanced oxidation processes(EAOPs) are considered efficient for VOC removal, based on their fast and versatile anodic electrochemical oxidation of pollutants. Many studies have reported the efficiency of removal of various types of pollutants using different anodes, but few studies have examined volatilization of VOCs during EAOPs. This study examined the removal efficiency for VOCs (chloroform, benzene, trichloroethylene and toluene) by oxidization and volatilization under a static stirred, aerated condition and an EAOP to compare the volatility of each compound. The removal efficiency of the optimum anode was determined by comparing the smallest volatilization ratio and the largest oxidization ratio for four different dimensionally stable anodes(DSA): Pt/Ti, IrO2/Ti, IrO2/Ti, and IrO2-Ru-Pd/Ti. EAOP was operated under same current density (25 mA/cm2) and electrolyte concentration (0.05 M, as NaCl). The high volatility of the VOCs resulted in removal of more than 90% within 30 min under aerated conditions. For EAOP, the IrO2-Ru/Ti anode exhibited the highest VOC removal efficiency, at over 98% in 1 h, and the lowest VOC volatilization (less than 5%). Chloroform was the most recalcitrant VOC due to its high volatility and chemical stability, but it was oxidized 99.2% by IrO2-Ru/Ti, 90.2% by IrO2-Ru-Pd/Ti, 78% by IrO2/Ti, and 75.4% by Pt/Ti anodes The oxidation and volatilization ratios of the VOCs indicate that the IrO2-Ru/Ti anode has superior electrochemical properties for VOC treatment due to its rapid oxidation process and its prevention of bubbling and volatilization of VOCs.

Optimal processes to remove chromaticity at E water treatment plant(WTP) mainly caused by algae of E lake in Jeju island were investigated based on lab-tests of chlorine and ozone oxidation. 42.9% of chromaticity of filtered water was removed by chlorine oxidation under pH 7.0∼8.0, dose of 1.0 mg/L with contact time of 30∼60 min. On the other hand, chromaticity removal was 71.4% when post-ozone dose of 0.9∼1.9 mg/L and pH 9.0, while it was increased to 86.7% under post-ozone dose of 3.1∼7.3 mg/L and pH 9.0. However, there was no significant chromaticity removal efficiency increase when ozone doses were higher than 5.0 mg/L regardless of feeding point(i.e., pre-ozonation and post-ozonation) and pHs(i.e., 7.0 and 9.0.) under the experimental conditions. Based on the results, chlorine oxidation using existing chlorination facilities at the WTP is recommended for lower chromaticity while ozone oxidation is recommended for higher chromaticity by installing new ozone feeding facilities.

Odorous compounds produced from blackwater commonly cause domestic nuisance complaints. In this study, aseries of experiments was conducted to apply an electrolytic oxidation system to abate the odor problems fromblackwater. The electrolytic process removes odorous compounds from the liquid sources using direct and indirectoxidation; therefore, the system performance mainly relies on electrode materials. Four different electrodematerials, SS304, SS316, Ti, Ti/IrO₂, were applied, and the electrolytic oxidation showed that hydrogen sulfideand organic constituents were effectively removed. However, the weights of electrodes, SS304 and SS316, weredecreased by 7.5~8% due to the electrochemical decomposition from the anode surface. In order to improve thedurability and economical feasibility, SS304 was used as the cathode while Ti/IrO₂ was used as the anode. Theelectrode combination with the different materials (Ti/IrO₂:SS304) showed the same odor removal efficiency asthat using the same material (Ti/IrO₂:Ti/IrO₂). Consequentially, the electrolytic reaction to oxidize odorous andorganic constituents in humane manure was strongly affected by the electrode materials, and its combination needsto be carefully selected to achieve better performance.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO2) 광촉매 첨가 PES (polyethersulfone) 구의 혼 성공정에서 주기적 물 역세척 시 유기물질의 영향 및 정밀여과(MF), PES 구 흡착, 광산화의 역할을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT) 측면에서 기존의 질소 역세척 결과와 비교하였다. 휴믹산 농도가 증가함에 따라 급격한 막 오염으로 Rf는 증가하고 J는 감소하여, VT는 휴믹산 농도 2 mg/L에서 가장 높았다. 탁도 처리효율은 물과 질소 역세척 모 두 휴믹산 농도와 상관없이 비슷하였다. 유기물질 처리효율은 물 역세척 경우 최대 휴믹산 10 mg/L에서 최소 71.4%이었으나, 질소 역세척에서는 거의 일정하였다. 물과 질소 역세척 모두 MF 및 PES 구, 자외선의 혼성공정(MF + TiO2 + UV)에서 Rf가 최소이고, J와 VT는 최대였다. 탁도 및 유기물질의 처리효율도 물과 질소 역세척에 상관없이 MF + TiO2 +UV에서 최대였 고, 공정이 MF로 단순화될수록 처리효율도 점차 감소하였다. 하지만 물 역세척에서는 광산화 보다 흡착이, 질소 역세척에 서는 흡착 보다 광산화가 더 주요한 역할을 하였다.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO2) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 유기물질의 영향 및 정밀여과(MF), PES 구 흡착, 광산화의 역할을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)를 통해서 비교 및 고찰하였다. 휴믹산의 농도가 증가함에 따라 급격한 막오염으로 인해 Rf 는 증가하고 J는 감소하였으며, VT는 휴믹산의 농도가 2 mg/L인 조건에서 가장 높았다. 광산화와 흡착의 영향을 알아보기 위해 휴믹산의 농도 4 mg/L와 6 mg/L에서의 결과를 비교하였다. 두 가지 조건에서 공통적으로 정밀여과(MF)만의 단독공정에서 막오염이 급격하게 진행되어 Rf값이 가장 높게 나타났고, 총여과부피(VT)는 광촉매와 자외선의 혼성공정(MF + TiO2 + UV)에서 가장 높은 값을 나타내었다. 탁도와 유기물질의 평균처리효율은 MF + TiO2 + UV 공정에서 가장 높은 값을 나타내었다.

탄소 한외여과막 및 광촉매 혼성 수처리를 위해 관형 여과막 외부와 원통형 막 모듈 내부 사이 공간에 광촉매를 충전하였다. 광촉매는 PP (polypropylene) 구에 이산화티타늄 분말을 플라즈마 화학증착 공정으로 코팅한 것이다. 휴믹산과 카올린 모사용액을 대상으로 막오염을 최소화하기 위해 10분 주기로 10초 동안 물 역세척을 시행하였다. 기존 결과와 동일하게 휴믹산을 10 mg/L부터 2 mg/L로 변화시킴에 따라, 막오염에 의한 저항(Rf)이 감소하여 2 mg/L에서 최대 총여과부피 (VT)를 얻었다. 탁도와 휴믹산의 처리효율은 각각 98.9%와 88.7% 이상이었다. UF 및 UF + TiO2, UF + TiO2 + UV 공정의 처리 분율 결과, 광촉매 흡착과 광산화에 의해 탁도는 거의 처리되지 않았으나, 광촉매 흡착 및 광산화에 의한 휴믹산 처리 분율은 각각 2.5%, 12.3%이었다. 기존 결과와 비교하면, 분리막의 재질과 기공의 크기에 따라 광촉매 흡착과 광산화에 의한 휴믹산의 처리 분율이 다르게 나타났다. 공정이 단순화될수록 180분 운전 후 막오염 저항(Rf,180)은 증가하였고, 최종 투과선속(J180)은 소폭 감소하였다.

MAO(Micro-Arc Oxidation) method was used to make surface on 6063 Al specimen. This study was focused on an influence of voltage, density of electrolyte and a period of treatment on the change of surface microstructure by using SEM(Scanning Electron Microscope), EDS(Energy Dispersive X-ray Spectroscopy). The microstructure shows higher roughness and thicker oxidized layer with increase of voltage and maintaining period of treatment. The density of electrolyte affected a formation of more dense surface and increase of a oxidized layer.

본 연구에서는 정수처리용 세라믹 한외여과 빛 광촉매의 혼성공정에서 휴믹산 농도 및 광산화, 흡착의 영향을 알아보았다. 휴믹산 농도 각각 2mg/L와 4 mg/L 일 때 UF 단독 공정 및 광촉매를 투입한 공정, UV를 조사한 공정을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피 (VΤ) 측면에서 고찰하였다. 휴믹산 농도가 낮아질수록 Rf는 급격히 감소하고 J는 증가하여, 휴믹산 농도 2 mg/L에서 VΤ는 가장 높았다. 탁도의 평균 처리효율은 휴믹산 농도가 증가할수록 감소하였으나, 4 mg/L에서 휴믹산의 처리효율이 가장 높았다. 이러한 결과는 낮은 휴믹산 농도에서 휴믹산 대부분이 분리막에 의해 제거되고 막을 통과한 일부 휴믹산은 광촉매에 흡착 산화되어, 처리수의 수질이 휴믹산 2 mg/L 와 4 mg/L 에서 거의 같고 원수의 수질은 4 mg/L에서 더 높기 때문이다. 광산화와 흡착의 영향 실험에서 UF + TiO2 + UV 공정의 J가 가장 높게 유지되어, 180분 운전 후 VΤ가 가장 높았다. 휴믹산 및 탁도의 처리효율을 비교한 결과, 휴믹산 농도가 2 mg/L 에서 4mg/L로 증가하였을 때 광산화 보다 광촉매 흡착이 더 주요한 역할을 하였다.

The investigation is to modify the mechanical and chemical properties of Mg alloys using a combination of rapid solidification and surface treatment. As the first approach, was gas atomized and pressure sintered by spark plasma sintering process (SPS), showing much finer microstructure and higher strength than the alloys as cast. Further modification was performed by treating the surface of PM Mg specimen using Plasma electrolytic oxidation (PEO) process. During the PEO processing, MgO layer was initiated to form on the surface of Mg powder compacts, and the thickness and the density of MgO layer were varied with the reaction time. The thickening rate became low with the reaction time due to the limited diffusion rate of Mg ions. The surface morphology, corrosion behavior and wear resistance were also discussed

1,4-Dioxane is an EPA priority pollutant often found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to decompose this compound effectively. Therefore, an advanced oxidation process system (AOP) was used for the degradation of 1,4-dioxane. This research investigates the effect of adding oxidants, such as ozone, air, and H2O2 during the UV irradiation of 1,4-dioxane solution. In order to analyze 1,4-dioxane, a modified 8270 method, which is an improved method of U.S EPA 8720, was used. Degradation efficiencies of 1,4-dioxane by only UV irradiation at various temperatures were not significant. However, The addition of oxidants and air bubbling in the UV irradiation system for 1,4-dioxane decomposition showed the higher 1,4-dioxane degradation rate. And, during AOP treatment the tendency of TOC changes was similar to that of 1,4-dioxane decomposition rate.

Oxidation behavior and microstructural characteristics of nano-sized Sn powder were studied. DTA-TG analysis showed that the Sn powder exhibited an endothermic peak at and exothermic peak at with an increase in weight. Based on the phase diagram consideration of Sn-O system and XRD analysis, it was interpreted that the first peak was for the melting of Sn powder and the second peak resulted from the formation of phase. Microstructural observation revealed that the powder, heated to under air atmosphere, consisted of agglomerates with large particle size due to the melting of Sn powder during heat treatment. Finally, fine SnO2 powders with an average size of 50nm can be fabricated by controlled heat treatment and ultrasonic milling process

A long- time aeration method was developed for purification of animal wastewater. Under repeated aereations of 4 hours on and 4 hours off, the higher removal rates were obtained which were in average of 99%, 96%, 92% and 50% for BOD, SS, total nitrogen and phosporous, respectively. In detail, the measured BOD concentrations of the influent and effluent were 2,700ppm and 40ppm while the SS concentrations in the primary chamber and of the effluent were about 3,000 and 110 ppm, respectively. Zeolite and activated carbon, applied for removing the nitrogen and phosphorous, showed a good absorption, especially zeolite for NH4-N and activated carbon for NO3-N and PO4-P. The treatment cost per head by this method amounts to 1,923 won and it comes to 1.6% in the whole production cost. Therefore, this method is economically available with the half cost of the conventional activated sludge process.