• Journal of Electrochemical Science and Technology
• /
• 제8권2호
• /
• pp.124-132
• /
• 2017

The performance of electrolytic processes using copper and catalyzed electrodes for enhanced nutrient removal with various catalyzers and combinations of electrodes was evaluated. The catalyzed electrodes removed more ammonia nitrogen than the copper electrode, but higher ammonia removal was achieved using a Pt/Ti anode. On the other hand, electrolysis using the Pt/Cu anode consumed less energy and cost less. During electroreduction, nitrate was better removed by a pair of copper electrodes than by the catalyzed electrodes. During electrolysis of synthetic wastewater, ammonia removal not only increased owing to direct oxidation at the anode, but was also influenced by indirect oxidation at the cathode. Platinum-coated copper and titanium cathodes actively produced oxidizers and thus removed more ammonia than a pure metal cathode. Although phosphorus was removable irrespective of the type of catalyzer, electrocoagulation using the copper electrode achieved complete removal of phosphorus in a period of less than 10 min.

• Journal of Electrochemical Science and Technology
• /
• 제8권1호
• /
• pp.35-42
• /
• 2017

In this study, the effect of electrolyte addition on the removal of organics and nutrients in electrochemical wastewater using a copper electrode, and the characteristics of the by-product of electrolysis were investigated. The removal of organics increased significantly as shorter reaction times upon the addition of chloride ion, and most of the electrolysis reaction was completed within 20 min. The reaction rate gradually increased in proportion to the $Cl^-$/COD ratio, whereas the highest removed mass of organic matter per mass of added electrolyte was observed at a $Cl^-$/COD ratio of 1. After the addition of electrolyte, significant removal of ammoniacal nitrogen was observed as a result of the enhanced generation of oxidizers such as hypochlorite. Excellent phosphorus removal was also achieved in a very short reaction time (within 2 min) by electro-coagulation. As the electrolysis progressed, the amount of by-product increased gradually, whereas a decrease of sludge volume index was observed after the addition of electrolyte. This indicated that the settling performance of the by-products was better, and their removal would be easily achieved.

• 대한환경공학회지
• /
• 제29권6호
• /
• pp.715-721
• /
• 2007

전자산업 중 반도체 및 LCD 공장과 같이 폐수에 불소가 다량 함유되어 있는 경우, 불소처리를 위하여 과잉으로 사용되는 소석회에 의하여 처리수의 잔류 칼슘농도가 높으며, 높은 잔류칼슘 농도는 폐수의 재이용 시 일반적으로 채택되는 membrane 공정의 불안정한 운전을 초래하게 된다. 따라서, 전자폐수의 재이용을 위하여 신뢰성 있으며, 경제적인 칼슘제거기술의 개발이 절실히 필요한 실정이다. 본 연구에서는 캐비테이션을 이용한 Hyperkinetic Vortex Crystallization(HVC) 공정을 적용하여 폐수중의 칼슘 이온의 calcification 속도를 촉진하였으며, HVC 공정 적용 시 기존 소다회법에 비하여 동일 약품 주입농도에서 31% 높은 칼슘제거효율을 보였다. 또한, 전자산업 폐수의 재이용을 위한 경제적인 칼슘제거효율인 70%를 달성하기 위한 최적 소다회 주입농도는 유입수 대비 530 mg/L였다. 반응조 내 동질의 반응 핵인 calcite seed 농도가 칼슘제거효율에 큰 영향을 주며, 최대 칼슘제거효율을 달성하기 위한 calcite seed 농도는 $800\sim1,200mg$ SSA이였다. 또한, 소다회 주입에 따른 calcite 발생량은 평균 0.30 g SS/g $Na_2CO_3$였다. HVC 케비테이션 생성장치의 설계 시 HVC 장치 통과횟수를 $2\sim5$회 범위에서 안전율을 고려하여 용량선정을 하여야 한다. HVC 공정을 이용한 연속회분식 운전 결과, 유입수 칼슘농도 변화폭은 $74\sim359$ mg/L(평균 173 mg/L)로 매우 컸던 반면, 처리수 칼슘농도는 $30\sim72$ mg/L(평균 49 mg/L)로 비교적 안정적인 처리효율을 보여주었다. 본 연구결과 HVC 공정은 화학약품 사용량의 절감 및 이에 따른 화학슬러지 발생량의 감소를 기대 할 수 있는 친환경기술로 유지관리비를 최소화할 수 있는 장점이 있었다.

• 대한환경공학회지
• /
• 제28권1호
• /
• pp.1-6
• /
• 2006

본 연구에서 수행한 입상형의 발포 폴리스티렌을 이용한 고도처리 공정은 기존의 상용화되거나 개발중인 영양염류 처리공정에 비해 수리학적 체류시간을 상당히 줄일 수 있고 동절기에도 온도의 영향을 크게 받지 않는 장점을 가지고 있다. 도시하수를 이용하여 bench-scale 연구를 수행한 결과 T-N 제거효율의 경우 HRT 6 hr 및 4 hr에서 각각 약 55% 및 51%로서 HRT가 짧아졌을때 단지 약 4%의 처리효율 감소가 관찰되었다. 온도 영향에 있어서 여름철과 겨울철의 T-N 제거효율을 비교해본 결과 T-N 제거 효율이 각각 약 65% 및 54%로 관찰되어 여름철이 겨울철에 비해 약 11% 더 높은 효율이 관찰되었으며 겨울철 효율저하는 주로 암모니아성 질소의 질산화가 원활이 이루어지지 않았기 때문인 것으로 관찰되었다. 유입부하 및 C/N 비에 관한 연구에서는 유량 및 농도의 변화가 심한 하 폐수 처리에 있어서도 안정된 처리수질을 확보할 수 있었으며, C/N 비가 감소에 따른 처리효율 저하가 크지 않음을 관찰 할 수 있었다. 따라서 본 개발 시스템을 기존의 중 소규모 하수처리장에 적용할 경우 유입수내의 유기물을 최대한 활용하여 영양염류를 처리할 수 있을 것이라 기대된다.

• 대한환경공학회지
• /
• 제34권3호
• /
• pp.155-161
• /
• 2012

본 연구에서는 고순도 메탄을 회수하기 위해서 Plug Flow Reactor와 External $CO_2$ Stripper를 결합한 중온 Methane Enhancement System을 개발하였다. 반응조 운전인자로서 알칼리도와 Leachate 순환율(LRR, Leachate Recycle Rate)이 바이오가스의 조성과 생성량 및 TVS 제거효율에 미치는 영향을 규명하였다. 고순도 메탄회수 공정 운전결과 OLR 2 g TVS/L-d, 알칼리도 4 g/L as $CaCO_3$, Leachate 순환율 3 v/v-d일 때 평균 94%의 높은 메탄함량을 나타내 고순도 메탄회수를 위한 최적조건임이 밝혀졌다. 이때 1일 반응조 단위 부피당 0.71부피의 메탄이 생성되었으며, TVS 제거율은 79%로서 Control Reactor의 94% 수준을 달성하였다.

• 한국연초학회지
• /
• 제24권1호
• /
• pp.38-45
• /
• 2002

This study was conducted to determine the smoke component concentration and the smoke distribution in the cambridge filter pad and cigarette filter with stalk position and grade of Korean leaf tobaccos. 12 grades of flue-cured and burley leaf tobaccos which were taken from the Kim-cheon and Ock-cheon leaf tobacco processing factory were used for this study. Six kinds of smoke components such as tar, nicotine, water, carbon monoxide(CO), carbon dioxide($CO_2$) puff No. collected in the cambridge filter pad and cigarette filter were analyzed. Also, nicotine/tar, CO/tar ratio were calculated from the analytical data. Puff no., CO, and $CO_2$ concentration of flue-cured and burley tobacco leaves at high stalk position were higher than those of low stalk position, and these components were increased in high grade of leaf tobacco. Compared with flue-cured tobacco, burley tobacco showed a little values of puff no., nicotine, and tar concentration. The pH range of burley tobaccos was broader than that of flue-cured tobaccos, and the ammonia concentration of burley tobaccos was significantly higher than that of flue-cured tobaccos. The pH value and ammonia concentration of burley tobaccos were decreased as stalk position of leaf tobaccos decreased. The distribution of smoke components collected in the cambridge filter pad and cigarette filter was different with a different grade and stalk position of tobacco leaves. In high stalk position of tobacco leaves, the portion of smoke components collected in the cambridge filter pad was also increased. The average nicotine, water, and tar removal efficiency by a cigarette filter in a flue-cured tobacco were 37%, 64%, and 48%, respectively. Compared with flue-cured tobaccos, smoke components of burley tobaccos had high nicotine and low water removal efficiency by a cigarette filter. The average ratio of nicotine/tar and CO/tar of flue-cured tobaccos and burley tobaccos were 0.097, 1.22, 0.094, and 0.97, in order. Nicotine/tar ratio was decreased and CO/tar ratio was increased in low stalk position.

• Asian Journal of Atmospheric Environment
• /
• 제10권4호
• /
• pp.190-196
• /
• 2016

The objective of this study is to obtain the optimal conditions to remove hydrogen fluoride (HF) generated from a variety of F-gas treatment processes. First, we selected $Ca(OH)_2$ and $CaCO_3$ as a reactant among the various alkali salts which have a high removal efficiency and a competitive price by forming a calcium fluoride precipitate. Additionally, various factors were investigated to improve the removal efficiency of HF. The conditions such as the settling time, agitating time and intensity, reaction temperature, and pH were considered as main factors. As a result, in the treatment process to remove HF through Ca-based alkali salts, the optimal conditions were a 120 min settling time, 30 min of agitation at 100 rpm, a pH of 4-8, and a reaction temperature of $40^{\circ}C$.

• 신재생에너지
• /
• 제16권1호
• /
• pp.68-76
• /
• 2020

Operational testing of the THIOPAQ^® facility that removes H₂S from landfill gas was performed for 746 days. The average H₂S removal efficiency was 99.4%, and the input quantities of air, NaOH, and nutrients per sulfur load were 13.1 ㎥/ton, 1.5 ㎥/ton, and 28.7 L/ton, respectively. The purity of the bio-sulfur produced from the facility was 94.8%, with 3.3% impurities, except for moisture. X-ray photoelectron spectroscopy showed that the compositional contents of amino acids and free amino acids of the bio-sulfur surface were 5,308 and 728 mg/kg, respectively. The mean particle size was 3.41 ㎛, which was much smaller than that of chemical sulfur. Based on these results, a high H₂S removal rate of more than 97% is feasible, and high value-added bio-sulfur, which is used as a fungicide because of its hydrophilic characteristics and small size, can be obtained at this facility.

• 한국환경과학회지
• /
• 제13권9호
• /
• pp.767-777
• /
• 2004

This study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of volatile hydrocarbons(VHC) at low ppb concentrations commonly associated with non-occupational indoor air quality issues. A series of experiments was conducted to evaluate five parameters (relative humidity (RH), hydraulic diameter (HD), feeding type (FT) of VHC, photocatalytic oxidation (PCO) reactor material (RM), and inlet port size (IPS) of PCO reactor) for the PCO destruction efficiencies of the selected target VHC. None of the target VHC presented significant dependence on the RH, which are inconsistent with a certain previous study that reported that under conditions of low humidity and a ppm toluene inlet level, there was a drop in the PCO efficiency with decreasing humidity. However, it is noted that the four parameters (HD, RM, FT and IPS) should be considered for better VHC removal efficiencies for the application of $TiO_2$ photocatalytic technology for cleansing non-occupational indoor air. The PCO destruction of VHC at concentrations associated with non-occupational indoor air quality issues can be up to nearly 100%. The amount of CO generated during PCO were a negligible addition to the indoor CO levels. These abilities can make the PCO reactor an important tool in the effort to improve non-occupational indoor air quality.

• 에너지공학
• /
• 제27권1호
• /
• pp.21-32
• /
• 2018

In this paper, we reported the current technologies of water scaling removal and also water recovery from the flue gases, which are funded by Department of Energy (DOE), USA. Globally, water resources are limited due to the climate change. The potential impacts of climate change is food and water shortages. In the $21^{st}$ century, water shortages and pollution are expected to become more acute as populations grow and concentrate in cities. At present, the water stress increases over 62.0 ~ 75.8% of total water basin area and decreases over 19.7 ~ 29.0%. Many renewable energy sources demand secure water resources. Water is critical for successful climate change mitigation, as many efforts to reduce greenhouse gas emissions depend on reliable access to water resources. Water hardness is one of the major challenge to coal power plants. Department of energy (DOE) funded and encouraged for the development of advanced technologies for the removal of hardness of water (scaling) and also water recovery from the flue gases from coal power plants.