Hyung-Il Choi

Nitrogen and Phosphorus Removal from Plating Wastewater Using the Soil Reactor

A laboratory experiment was conducted to investigate nitrogen removal from plating wastewater by a soil reactor. A combination of soil, waste oyster shell and activated sludge were used as a loading media in a soil reactor. The addition of 20% waste oyster shell and activated sludge to the soil accelerated nitrification (88.6% removal efficiency) and denitrification (84.3% removal) in the soil reactor, respectively. In continuous removal, the influent was mostly converted to nitrate nitrogen in the nitrification soil reactor and only a small amount of was found in the effluent. When methanol was added as a carbon source to the denitrification soil reactor, the average removal efficiency of significantly increased. The removal by methanol addition in the denitrification soil reactor was mainly due to denitrification. The phosphorus was removed by the waste oyster shell media in the nitrification soil reactor. Moreover, the phosphorus removal in the denitrification soil reactor was achieved by synthesis of bacteria and the denitrification under anaerobic conditions. The approximate number of nitrifiers and denitrifiers was soil at a depth of and soil at a depth of , respectively, in the soil reactor mixed with a waste oyster shell media and activated sludge.

Nitrogen and Phosphorus Removal from Domestic Wastewater by MLE Process Combined with Aluminum Corrosion Process

The pilot plant experiment was performed to investigate phosphorus and nitrogen removal from domestic wastewater by MLE process combined with aluminum corrosion reactor. When operating 0.5Q and 1Q to internal recycle and sludge recycle in the MLE process, the effluent concentration of internal recycle 0.5Q were higher than internal recycle 1Q, the removal efficiency rates of -N in the internal recycle 0.5Q were was higher than internal recycle 1Q. Denitrification rates were about 86.8% in internal recycle and sludge recycle 0.5Q. When operating 0.5Q to internal recycle and sludge recycle in the MLE process, the removal efficiency rates of total nitrogen was the highest. The removal efficiency rates of total phosphorus was about 91.5% in the aluminum corrosion reactor.

Adsorption Characteristics of Nitrate-nitrogen by Carbonaceous Material Prepared from Oak

Abstract The adsorption behavior of nitrate nitrogen was investigated from aqueous solution using char prepared from oak chip. The removal rate of nitrate nitrogen was found to be dependent on temperature and it is increased as the temperature increase. Adsorption equilibrium data of nitrate nitrogen on oak char. reasonably fitted Langmuir and Freundlich isotherm models. The adsorption energy obtained from D-R model was 12.5 kJ/mole at 20 ℃ indicating an ion exchange process as primary adsorption mechanism. Thermodynamic parameters such as △ G o, , △ H o , and △ S o were -23.76 kJ/mole, 26.1 kJ/mole and 89.7 J/K·mole at 20 ℃ , respectively, indicated that the nature of nitrate nitrogen adsorption is spontaneous and endothermic. Key Words : Oak char, Nitrate nitrogen, Adsorption, Adsorption isotherm 1) 1. 서 론 지하수 오염은 유기용매, 농약 등의 유기화학물질, 중금속 등을 비롯한 병원성 박테리아, 바이러스, 또는 인간과 동물의 기생충을 함유한 배설물이나 하수 등에 의하여 발생한다. 질산성 질소는 강우에도 함유되어 있지만 인간 및 산업 활동과 깊은 관계가 있으며 주 * Corresponding author : Kyung-Hoon Cheong, Department of Environmental Engineering and BK21 Team for Bio- hydrogen Production, Chosun University, Gwangju 501- 759, Korea Phone: +82-62-230-6628E-mail: khjung@chosun.ac.kr요 오염원으로는 농업계(유기, 무기비료, 식물의 잔사), 축산계(축산폐기물의 농지 환원 , 가축분뇨의 지하 침투), 생활하수나 공장폐수의 지하침투 등을 들 수 있다(細見, 1996). 질산이온으로 오염된 물을 마시면 소화기관에서 아질산이온으로 환원되며 , 특히 유아의 경우 산소전달을 방해하여 청색증(methemoglobinemia)이라는 질병을 야기하며 심한 경우 유아가 사망하는 것으로 보고되고 있다(Hoek와 Klapwijk, 1987). 또한 질산이온 및 아질산이온은 유력한 발암물질로 알려진 N-nitroso 화합물을 형성하는 잠재력을 가지고 있는 것으로 보고되고 있기 때문에 먹는 물 및 먹는 샘물의 수질기준에서도 10

A Study on the Road Traffic Noise Restriction Factors that Affect the Price of Apartment Complexes

In this research, we measured the number of lanes, distance, disposition of apartment that are affecting the road traffic noise to evaluate the current condition of G citys road traffic noise. We decide on a basis regarding an apartment price formation factor, and the apartment current price and the results that compared. To have a point scale, we set the maximum road traffic noise at a 8 lane road for 5 points, give 4 points for a 6 lane road, which has a difference compared to a 8 lane road, give 3 points for a 4 lane road, which has a difference compared to a 8 lane road, and set 2 points for a 2 lane road and lower. If we set the standard floor plan as horizontal and a living room facing the roadside, the horizontal and living room facing the opposite side of the road is 1 point because it differs by 14.1 dB(A), and the vertical is 3 points since the difference is 5.3 dB(A). If we make grades by the distance, making standard the fifth floor with little soundproof effect from apartment to road, we observe a measurement below 2.9 dB(A) at a distance of less than 10 m and 5 dB(A), decreased at a distance of 20 m. Therefore, 4 points were given for less than 10m, 3 points for , 2 points for more than 20 m as we can apply the effect of a decay distance of line sound source and the decrease in noise effects of more than 6 dB(A), 1 point for more than 40m, and 0 points for more that 80 m since it is negligible. 28 apartments got 0 points because there is no effect of road traffic noise from other apartments, and 50 apartments where only the road at one side effect them got points. 4 apartments (17-2, 6-3, 10-4, 3-3) received over 20 points. 15 cases showed a difference between developer price and resale price, and 11 cases (73%) among them showed the same trend (price increases with a low road traffic noise restriction factor point) with the point of road traffic noise restriction factor. 4 cases demonstrated the opposite trend, showing price increases with a high restriction factor point. Among the 4 cases, case numbers 2,6 and 9 appear to be more affected by the location factor (business district) than the road traffic noise restriction factor, and case number 1 appears to be affected by the building factor (openness and direction).

Degradation of Cyanide by Activated Sludge Immobilized with Polyethylene Glycol

The activated sludge obtained from wastewater coke oven plant was immobilized by entrapment with polyethylene glycol (PEG). The effects of several factors on the biodegradation of from. synthetic wastewater were investigated using batch and continuous reactors. The degradation rate of increased with increasing of the immobilized bead volume in the reactor. Approximately 7.65mg/L of was produced upon the degradation of 35mg/L of . When high concentrations of the toxic cyanide complex were used in the testing of cyanide degradation, the free activated sludge could be inhibited more than that of the immobilized activated sludge. When the phenol concentration was higher than 400mg/L in the synthetic wastewater, approximately 98.4% of was removed within 42 hours by the immobilized activated sludge. However, the cyanide was not completely degraded by the tree activated sludge. This indicates that high phenol concentrations can act as a toxic factor for the free activated sludge. A concentration of less than 1mg/L was achieved by the immobilized sludge at the loading rate of 0.025kg . Moreover, it was found that the HRT should be kept for 48 hours in order to obtain stable treatment conditions.

A Study on the Characteristics of Railroad Traffic Noise

This study has been conducted to achieve the following objectives: First, in order to understand the horizontal propagation and attenuation characteristics for the railroad traffic noise, we selected areas within 100 meters away from the railroad and then selected Saemaul-ho and Mugoongwha-ho as the subjects for our experiment. In this way, we analyzed the horizontal propagation and attenuation characteristics for the traffic noise occurring in diversified areas. Second, in order to understand the vertical propagation and attenuation characteristics for the railroad traffic noise, we measured and analyzed the distributional characteristics of vertical sound pressure levels on each floor of multi-storied apartment buildings according to changes of traffic load and types, and the existence or nonexistence of soundproof walls. For the case of the railroad traffic noise, we also selected Samaul-ho and Mugoongwha-ho as the subjects for our experiment, and we measured and analyzed the different noise levels on each floor of multi-storied apartment buildings from the soundproof wall. The results of Horizontal propagation and attenuation characteristics for the railroad traffic noise are as follows: In cases of the flat land, cutting land, and bridge area, as distance increases, the sound pressure level steadily decreases. The sound pressure level for the bridge area is higher than that of the flat land with a measurement of . Vertical propagation and attenuation characteristics for the railroad traffic noise are as follows: The amount of sound pressure level decrease is for Samaul-ho and for Mugoongwha-ho when measuring the vertical sound pressure levels at heights lower than 4.5 m, which indicates a fairly large decrease. At 6 m, the amount of decrease is 8.6 dB(A) for Samaul-ho and 8.2 dB(A) for Mugoongwha-ho, which indicates a small decrease.

Nitrogen Removal from Synthetic Domestic Wastewater Using the Soil Column

A laboratory experiment was performed to investigate nitrogen removal by the soil column. The addition of 20% waste oyster shell to the soil accelerated nitrification in soil column. The concentration in the effluent decreased with the decrease of HRT(Hydraulic Retention Time). When methanol and glucose added as carbon sources, the average removal rates of T-N(Total Nitrogen) were 82% and 77.9%, respectively. The removal by methanol supplementation in soil column can likely be attributed to denitrification. In continuous removal of nitrogen using the soil column, the COD(Chemical Oxygen Demand) and removed simultaneously in organic matter decomposing column. The greater part of was nitrified by the percolated through nitrification column, and the little was found in the effluent. The T-N of 87.4% removed at HRT of 36 hrs in denitrfication column. Because of nitrified effluents from nitrification column are low in carbonaceous matter, an external source of carbon is required.