Bioremediation has been recognized as a suitable alternative to conventional methods of removing contaminants, and it uses fungi, bacteria and microalgae. In contrast to other organisms, microalgae are unique in that they have the ability to perform photosynthesis like plants and to utilize organic/inorganic carbon substrates, in a process called phytoremediation. Microalgae can populate a reaction site rapidly and enhance the bioremediation efficiency. In this study, Chlorella vulgaris was used to evaluate the removal potentials of the nutrients (N and P) and heavy metals (Cu and Zn) from swine wastewater. The optimum growth conditions for Chlorella vulgaris and the removal potentials of N, P, Cu, and Zn from synthetic wastewater using Chlorella vulgaris were investigated. Based on the results, the applicability of this microalga to on-site wastewater treatment was examined. Optimal growth conditions for Chlorella vulgaris were established to be 28℃, a pH of 7, and light and dark cycles of 14:10 h. As the concentrations of the nutrients were increased, the efficiencies of N and P removal efficiencies by Chlorella vulgaris were decreased in the single and binary mixed treatments of the nutrients, respectively. Further, the efficiencies of Cu and Zn removal also decreased as the heavy metals concentrations added were increased, both in the single and binary mixed treatments. In addition, the efficiency of Cu removal was higher than that of Zn removal. Our results indicate that Chlorella vulgaris could be used in treatment plants for the removal of nutrients and heavy metals from swine wastewater.

In this study, we evaluated the photocatalytic oxidation efficiency of aromatic volatile hydrocarbons by using WO3–doped TiO2 nanotubes (WTNTs) under visible-light irradiation. One-dimensional WTNTs were synthesized by ultrasonic-assisted hydrothermal method and impregnation. XRD analysis revealed successful incorporation of WO3 into TiO2 nanotube (TNT) structures. UV-Vis spectra exhibited that the synthesized WTNT samples can be activated under visible light irradiation. FE-SEM and TEM images showed the one-dimensional structure of the prepared TNTs and WTNTs. The photocatalytic oxidation efficiencies of toluene, ethylbenzene, and o-xylene were higher using WTNT samples than undoped TNT. These results were explained based on the charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. Among the different light sources, light-emitting-diodes (LEDs) are more highly energy-efficient than 8-W daylight used for the photocatalytic oxidation of toluene, ethylbenzene, and o-xylene, though the photocatalytic oxidation efficiency is higher for 8-W daylight.

Trains have been a major means of transport in Korea during these past decades. However, train facilities such as stations and repair shops are contaminated with organic and inorganic substances. There is a high probability of train facility contamination with polyaromatic hydrocarbons (PAHs). This study evaluated the PAH and heavy metal contamination of soil near railroads in the Kyungpook area. A total of 18 soil samples were collected from the railroads and analyzed for 16 PAHs and 6 heavy metal species. The contamination level of the top soil was found to be slightly higher than that of the subsoil for contamination with PAHs. The ratio of carcinogenic PAH concentration to the total PAH concentration was relatively high, with a maximum of 0.9. The toxicity equivalent (TEQ) of the PAHs were 500.6 ng/kg in the topsoil and 355.5 ng/kg in the subsoil. The ratio of low molecular PAHs (LPAHs) to high molecular PAHs (LPAHs) ranged from 6.7 to 29.5; this shows that contamination is primarily due to combustion of fuel rather than due to petroleum. The ratio of phenanthrene to anthracene and the ratio of fluoranthene to pyrene also show that contamination occurred due to combustion for transportation. The heavy metal contamination level was lower than the Korean standard, but higher than the background concentration; this indicates that the soil was affected by the operation of the railways.

The quality standards of solid refuse fuel (SRF) define the values for 12 physico-chemical properties, including moisture, lower heating value, and metal compounds, according to Article 20 of the Enforcement Rules of the Act on Resource Saving and Recycling Promotion. These parameters are evaluated via various SRF Quality Test Methods, but problems related to the heavy metal content have been observed in the microwave acid digestion method. Therefore, these methods and their applicability need improvement. In this study, the appropriate testing conditions were derived by varying the parameters of microwave acid digestion, such as microwave power and pre-treatment time. The pre-treatment of SRF as a function of the microwave power revealed an incomplete decomposition of the sample at 600 W, and the heavy metal content analysis was difficult to perform under 9 mL of nitric acid and 3 mL of hydrochloric acid. The experiments with the reference materials under nitric acid at 600 W lasted 30 minutes, and 1,000 W for 20 or 30 minutes were considered optimal conditions. The results confirmed that a mixture of SRF and an acid would take about 20 minutes to reach 180 oC, requiring at least 30 minutes of pre-treatment. The accuracy was within 30% of the standard deviation, with a precision of 70 ~ 130% of the heavy metal recovery rate. By applying these conditions to SRF, the results for each condition were not significantly different and the heavy metal standards for As, Pb, Cd, and Cr were satisfied.

Proximal femoral fractures are common in older adults. Zimmer natural nail (ZNN, Cephalomedulary Asia; Zimmer, Warsaw, IN, USA) known as useful in immobilizing the fractures of the proximal femoral fractures, have a critical complications like femoral head perforation and cut through in pelvic bone. We report a case that the femoral head perforation by the hip screw occured within 2 months of the operation, and 8 months after operation, the hip screw is completely separated from the metal body and cut through the pelvis.

We evaluated the radiologic, clinical results and the complications of minimally invasive percutaneous medial plate fixation in distal tibial metaphyseal fracture. From January 2010 to December 2016, 31 patients with distal tibial fracture treated by medial plate fixation using Minimal Invasive Plate Osteosynthesis (MIPO) technique were analyzed. The duration of followup was more than 1 year. We evaluated clinical results by IOWA ANKLE rating system, union time by simple X-ray and complication. The bone union was achieved in all cases at average 16.7 weeks. Average IOWA ANKLE rating score was 90.3 point. At the last follow-up, there was no non-union, angular deformity more than 5 degrees or infection. We concluded that minimal invasive percutaneous medial plate fixation for distal tibial metaphyseal fractures is a safe and useful method if there is no medial wound problem, and it is important to pay close attention to prevent angular deformity during surgery.

본 연구에서는 대전 관평천의 도시유역에서 2017~2018년에 발생한 강우 20건의 유출수를 연속적으로 채취하여 As, Cd, Cr, Cu, Ni, Pb 및 Zn 의 중금속 및 총고형물질(TSS) 농도와 유량을 분석하고, 강우특성과 수질 변화의 강우사상별 및 시간별 상관관계를 조사하였다. 일정 강우강도에서 오염물질의 최대농도는 강우 초기에 발생하는 경향을 나타냈으나, 강우량 및 강우강도가 작은 경우에는 일정 시간 경과 후 발생하는 것이 관찰 되었다. 강우지속시간은 중금속 농도 및 부하량과 큰 상관성을 보이지 않았다. Cu와 Zn을 제외한 중금속 질량은 강우강도(0.60~0.88) 및 총강우 유출량(0.74~0.89)과 상대적으로 높은 상관관계를 나타냈다. 강우 시 유량가중평균농도와 선행무강우일수 또한 양의 상관성(0.54~0.73)을 보 이는 반면, 30분 강우강도로 표현된 시간별 유출량과 TSS 및 중금속 농도는 전혀 상관성을 나타내지 않았다. 무강우 기간 동안 지표면에 축적된 오 염물질이 최소한의 강우 에너지에도 세척효과가 발생하여 강우특성과는 무관하기 때문인 것으로 추정된다. 중금속과 TSS 농도의 시간에 따른 변화특성은 상관계수가 0.68~0.87로 양호한 수준을 나타냈다. 이는 고형물질의 이동과 중금속 물질의 이동이 함께 발생한다는 것을 시사하며 동시에 중금속이 고형물질에 흡착되어 이동한다는 것을 의미한다. 따라서 비강우 시에 유역 표면의 고형물질을 청소 등으로 사전에 제거할 경우 하천으로 유입되는 중금속오염물질의 양을 현격하게 저감할 수 있을 것으로 판단된다.

This study is an attempt to develop modular house structural systems with safety seismic performances under maximum seismic load of 0.3G. The modular house system was designed with joints (plan) using four-clip simple fastening type, and was also adopted a type of double inter-metallic assembly modular systems using a light metal. The seismic performance was evaluated.

The purpose of this study is to investigate the ultimate strength of carbon steel (SS400) fillet-welded connections with weld metal fracture through monotonic tensile test. Specimens of CTFW series (transverse fillet weld against loading direction), CLFW series (longitudinal fillet weld against loading direction) and CFW series (a combination of transverse weld and longitudinal weld) failed by tensile fracture, shear fracture and block shear fracture, respectively. Test strengths were compared according to welding direction and weld length

The purpose of this experimental study is to develop an water soluble silicone acrylic surface finishing material of car parks. The heavy metal contents test was conducted in order to supply a guideline for developing a top finishing material. As a results, the sample was satisfied with the quality standard regarding heavy metal contents which is prescribed in KS F 3888-2 of En 71-3. As conclusion, this study confirmed that the developed top finishing material could be an optimized material usable for car parks’ deck.

This study investigated both leaching of heavy metals and ecological toxicity when coal bottom ash (CBA) generated by power plants has been used to reduce both erosion and turbidity of surface runoff at construction sites. The Korean leaching test (KLT) method, sequential extraction method, and acute toxicity test using Daphnia magna were performed to evaluate the environmental impacts and the ecological risks of CBA. According to the results of the KLT method of CBA, trace amounts of Cu were leached at limit of quantitation whereas metal leaching was not monitored for other heavy metals. Through the sequential extraction method of CBA, the relatively high leaching potential was found for As and Pb due to greater fraction of exchangeable (F1) and bound to carbonates (F2), and reasonable probability of leaching under the reducing/anaerobic environment was expected for Cu due to high faction of bound to Fe?Mn oxides (F3). However, significantly low probability of leaching was expected for Cd, Cr, Ni, and Zn with grater fractions of bound to organic matter (F4) and residual (F5). Additionally, total amount of heavy metals in CBA was lower than criteria for soil pollution concerns, and were similar or slightly lower levels than the ‘15 National soil average concentration excluding Cr6+. Finally, acute toxicity test using Daphnia magna display no impact for mobilization and lethality in either the prefiltration or post-filtration experiment, indicating that the ecological toxicity was insignificant with zero values of toxic unit. Consequently, no environmental impacts or ecological toxicity are expected when CBA generated by power plants has been used to reduce both erosion and turbidity of surface runoff at construction sites.

Polluting gases emitted from industrial sites take compound forms consisting of gaseous and particulate phases. Localization of PTFE membrane filters has thus been initiated to remove particulate materials and mercury, which is a heavy and hazardous metallic element. More specifically, a PTFE membrane filter was fabricated by thermal laminating technology to vary porosity on the filter surface for removal of particulate materials thereon. Optimized equi-biaxial stretching ratio control enables minimization of large-size pore formation with an average pore size of 0.58 μm and improved air permeability of 8.03 cm3/cm2/sec. Various adsorbents were tested for removal of mercury vapor by surface treatment of the PTFE membrane filter. The filter’s surface was further altered using functional amine group compounds: one composed of silane coupling agent (APTMS) was found suitable as a mercury adsorbent. When ACF with a large surface area was used as support material, mercury removal efficiency increased threefold to 0.162 mg/g-ACF. Furthermore, the developed PTFE membrane filter was tested in its capacity of differential pressure and filtering efficiency using a pilot scale particulate removal unit. Stable and consistent differential pressure was maintained during long-term operation and less frequent periods of filter shutdown due to pores filling with 99.96% of particulate removal efficiency, which was more than satisfactory filtration efficiency.

Li-Cd 합금을 이용한 환원추출방식을 LiCl-KCl 기반의 drawdown 공정에 적용하게 되면, LiCl-KCl 공융염의 조성이 파괴되므로 공정온도를 높여야 하며, 전해정련 및 전해제련과 같은 공정에 LiCl-KCl 용융염을 재사용할 수 없게 된다. 따라서, 본 연구에서는 공융염 조성에 적합한 Li-K-Cd 합금을 제조하였으며, 이를 이용하여 U와 Nd가 포함된 LiCl-KCl 염에 투입하여 용 융염 내 UCl3의 제거가 가능한지 평가하였다.

In this study, a metal-organic framework (MOF) material NH2-MIL-101(Fe) was synthesized using the solvothermal method, and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectrophotometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and surface area measurements. The XRD pattern of the synthesized NH2-MIL-101(Fe) was similar to the previously reported patterns of MIL-101 type materials, which indicated the successful synthesis of NH2-MIL-101(Fe). The FT-IR spectrum showed the molecular structure and functional groups of the synthesized NH2-MIL-101(Fe). The UV-visible absorbance spectrum indicated that the synthesized material could be activated as a photocatalyst under visible light irradiation. FE-SEM and TEM images showed the formation of hexagonal microspindle structures in the synthesized NH2-MIL-101(Fe). Furthermore, the EDS spectrum indicated that the synthesized material consisted of Fe, N, O, and C elements. The synthesized NH2-MIL-101(Fe) was then employed as an adsorbent and photocatalyst for the removal of Indigo carmine and Rhodamine B from aqueous solutions. The initial 30 min of adsorption for Indigo carmine and Rhodamine B without light irradiation achieved removal efficiencies of 83.6% and 70.7%, respectively. The removal efficiencies thereafter gradually increased with visible light irradiation for 180 min, and the overall removal efficiencies for Indigo carmine and Rhodamine B were 94.2% and 83.5%, respectively. These results indicate that the synthesized MOF material can be effectively applied as an adsorbent and photocatalyst for the removal of dyes.

In this study, heavy metal levels at the sediment monitoring network site upstream of the Gangjeong-Goryeong weir in the Nakdong River were surveyed from 2012 to 2016. We assessed the sediment pollution level using various pollution indexes based on ICP-MS analysis. The stream sediment pollution assessment standard, established through Regulation No. 687 of the National Institute of Environmental Research (2015), pollution load index (PLI), potential ecological risk index (RI), and mean PEL Quotient (mPELQ) were used to evaluate the sediment pollution level. We verified the representativeness of the monitoring point through the distribution of sedimentation and scour behavior by river bed surveying using anacousticDopplercurrentprofiler.

기존의 정수처리 방법으로는 제거되지 않는 물질이 발생함에 고도정수 처리 시설의 도입이 증가하고 있다. 그러나 오존을 이용한 고도정수처리 시설의 내부 방수·방식재는 오존의 산화력에 의해 열화되며 콘크리트까지 영향을 미쳐 내구성 저하의 원인이 된다. 본 연구에서는 내오존성 및 내화학성이 뛰어난 금속 패널을 기존의 시공법 보다 손쉬운 방법으로 시공하기 위한 방법으로 금속용사 공법을 이용하여 수처 리 시설 콘크리트 구조물의 열화를 원천적으로 방지하기 위한 마감공법 개발 연구의 일원으로 용사금속 종류 및 피막의 표면처리 방법에 따른 내오존성 평가를 실시하였으며, 오존처리 후의 부착강도를 평가하였다. 실험결과 용사금속 Ti이 용사 후에도 내오존성이 뛰어난 것으로 나타 났으며 표면처리 방법으로는 테프론계 봉공처리제를 사용하여 마감하는 것이 내오존성 및 부착성능 확보에 가장 적합한 방법이라 판단된다.

This study investigated the concentration of heavy metals in blast-furnace slag cement by changing the content ratio between blast-furnace slag and ordinary Portland cement for the safe recycling of blast-furnace slag in the cement industry. The analysis of the three main materials of the cement (ordinary Portland cement, blast-furnace slag, and the alternative raw materials), resulted in the ordinary Portland cement having the highest concentration of heavy metals. Also, it is concluded that the heavy metal content of blast-furnace slag cement is mainly attributed to the content of ordinary Portland cement. As the content of furnace slag during the manufacture of cement increases, the overall heavy metal content of the furnace slag cement becomes low. This was highly evaluated as a resource in the cement-production process, in respect of the effective recycling of resources and the safe management of hazardous materials.

The purpose of this study was to verify safe and environmentally-sound recycling of blast-furnace slag in the cement industry. This was accomplished by analyzing the heavy metal contents of three kinds of raw materials: blast-furnace slag, Portland cement, and the substitutes, which were mainly input into the manufacture of cement. The research revealed that, in the five samples tested, the heavy metal level in the blast-furnace slag cements (5.90 ~ 8.38 mg/kg for Cr6+) is lower than the ordinary Portland cement (11.04 ~ 14.92 mg/kg for Cr6+). This suggests that both raw materials have low heavy metal contents compared with the 20 mg/kg limit enforced by the autonomic convention in Korea. As for the substitutes, there was no decisive effect on the overall heavy metal content because of the low input ratio of 2.5%. Therefore, it is of high utility value to recycle the blast-furnace slag in the cement industry, considering slag can dilute the overall heavy metal contents in the cement products.

본 연구는 강원도 도계광업소 수계에 발생한 적갈색침전물을 대상으로 침전환경을 파악하고, 중금속함량, 광물조성 및 그에 따른 분광학적 특성을 분석하였다. 적갈색침전물의 pH 범위는 7.59-7.94로 침전환경은 중성에 해당한다. X선형광분석 결과 철이 평균농도보다 높게 검출되었으며, 니켈, 구리 및 아연의 오염도가 높은 것으로 판명된다. X선회절분석 결과 돌로마이트, 방해석, 침철석, 자철석, 고령토, 엽납석, 석영 및 알루미늄 이소프로폭사이드의 광물이 확인되었다. 중금속 오염에 따른 분광학적 특성을 분석한 결과, 중금속함량이 증가함에 따라 가시광선 영역에서는 반사도가 증가하는 추세를, 적외선 영역에서는 반사도가 감소하는 추세를 보인다. 적갈색침전물의 분광특성은 침철석, 자철석, 고령토, 엽납석 및 알루미늄 이소프로폭사이드에 의해 발현되는 것으로 판단된다.

본 연구는 acid bake-water leaching system (AWS)를 이용하여 Au 정광으로부터 경제적이고 친환경적인 유용금속 용출을 위하여 황산염 용매제의 적용성을 파악하는 것이다. AWS 실험은 전기로를 이용하여 다양한 baking 온도(100℃~500℃)와 황산염 용매제(H2SO4, K2SO4, (NH4)2SO4, MgSO4, CaSO4) 조건에서 수행하였다. Baking 온도가 400℃까지 증가할수록 유용금속의 용출률은 증가하였다. 용출시간에 따른 AWS 실험결과, 최대 용출률 조건은 (NH4)2SO4 용매제이었다. 본 연구를 통하여 (NH4)2SO4 용 매제가 AWS를 이용한 유용금속 용출에 있어 효과적인 용매제로 사용가능함을 입증하였다.