In this study, a direct contact membrane module was manufactured to be used in a pilot scale membrane distillation process to treat 3 m3/day of the digestate produced from anaerobic digestion of livestock manure. In order to investigate the performance of the membrane module, permeate flux was measured with and without spacer inside the module under various condition of temperature difference and cross flow velocity (CFV) through the membrane surfaces. Flux recovery rate after chemical cleaning was also investigated by applying three different cleaning methods. Additionally, thermal energy consumption was theoretically simulated based on actual pilot plant operation conditions. As results, we observed flux of the module with spacer was almost similar to the theoretically predicted value because the installation of spacer reduced the channeling effect inside the module. Under the same operating condition, the permeate flux also increased with increasing temperature difference and CFV. As a result of chemical in-line cleaning using NaOCl and citric acid for the fouled membranes, the recovery rate was 83.7% compared to the initial flux when NaOCl was used alone, and 87% recovery rate was observed when only citric acid was used. However, in the case of using only citric acid, the permeate flux was decreased at a rapid rate. It seemed that a cleaning by NaOCl was more effective to recover the flux of membrane contaminated by the organic matter as compared to a cleaning by citric acid. The total heat energy consumption increased with increasing CFV and temperature difference across the membrane. Thus, further studies should be intensively conducted to obtain a high permeate flux while keeping the energy consumption to a minimum for a practical application of membrane distillation process to treat wastewater.

In this study, we applied a membrane distillation process to investigate a feasibility of treating a wastewater with high concentration of organic matters including nitrogen and phosphorus. The laboratory scale experiment was performed by using a hydrophobic PVDF membrane with the pore size of 0.22 μm and porosity of 75%. The installation was direct contact type where the temperature difference between a feed and permeate side was controlled to have a range from 20 to 60°C. We observed a flux variation and a concentration changes of COD, PO4 3-－P, NH4 + -N and conductivity of feed side as well as permeate side with various temperature differences (20 to 60°C), cross flow velocities (0.09 to 0.27 m/s) through the module, and pH (6.6 to 12.0) of the feed that has the initial concentration of COD about 1,000 mg/L, total nitrogen 390 mg/L, total phosphorus 10 mg/L, conductivity of 7,000 μs/cm. The results showed that the average flux was ranged from 4 to 40 L/m2/hr which was almost similar with the flux of NaCl and deionized water used as a feed solution. The lowest flux was obtained at the operating condition with the temperature difference of 20°C and cross flow velocity of 0.09 m/s while the highest one was measured with 60°C and 0.27 m/s. Above 99% of COD and PO4 3- -P in the feed could be rejected regardless of an operating condition. However, the removal rate of ammonium nitrogen was varied from 64 to 99% depending on the pH of feed solution.

본 연구는 Sprague-Dawley 계통의 4주령 랫드에서 MSG의 반복경구투여 독성평가와 행동실험을 통해 어린랫드의 인지능력과 불안감에 미치는 영향을 평가하기 위해서 시행하였다. 시험군은 MSG 대신 distilled water를 투여한 대조군(Control, n = 4), MSG를 3 g/kg을 투여한 군(Low, n =4), MSG를 5 g/kg을 투여한 군(High, n = 4)으로 나누어 4주 동안 주5회 경구투여를 하였다. MSG의 안정성을 확인하기 위해 다음과 같은 관찰 및 검사를 하였다. 검사항목으로는 체중의 변화, 임상증상, 행동실험인 T-maze, Elevatedplus-maze와 혈액학적 검사, 혈청생화학적 검사, 병리조직 학적 검사를 관찰한 결과 모든 투여군 및 대조군에서 특이할 만한 임상증상과 체중변화는 관찰되지 않았으며, 폐사 및 빈사 동물은 시험 전 기간을 통하여 발견되지 않았다. 행동실험인 T-maze 결과 MSG 고용량 투여군에서 움직이는 횟수가 감소하다 증가하는 양상을 보였고, Elevatedplus-maze 실험에서는 MSG 고용량 투여군의 Open arm의 출입빈도가 증가하는 등 유의적인 변화가 나타났다. 혈액학적 검사 및 혈청생화학적 검사에서는 대조군과 비교 시 유의적인 변화가 관찰되었지만 그 수치가 정상범위 안에 포함되기 때문에 이상을 나타내지 않았다. 병리조직검사 또한 약간의 염증발생 소견이 나왔지만 정상범위 안에 포함되기 때문에 이상을 나타내지 않았다고 판단했다. 따라서, 어린랫드를 이용한 MSG의 반복투여 독성시험 결과 특이할만한 신체적인 변화는 나타나지 않았으나 고용량의 MSG 투여는 어린랫드에서 인지능력의 저하 및 행동의 불 안을 유발할 가능성이 있다고 사료된다.

A lab-scale Anaerobic Baffled Reactor (ABR) was applied to treat a primary sludge taken from a municipal wastewater treatment plant. In this experiment, acidogenic reaction was promoted by operating the ABR with short hydraulic retention time (HRT) to produce sufficient volatile fatty acids (VFA) instead of production of methane. The performance of ABR on the VFA production and total solids reduction was observed with different operating conditions with 2, 4, 6, and 8 days of HRT. Corresponding organic loading rates were 6.7, 3.4, 2.2, and 1.6 kgCODcr /m3·day. As HRT increased the removal rate of TCOD was also increased (82.5, 84.2, 96.9, and 95.9 % in average for HRT of 2, 4, 6, and 8 days, respectively) because the settlement of solids was enhanced in the baffle by the decrease of upflow velocity. At HRT of 2 days the average concentration of VFA in the effluent was measured at 1,306±552 mgCOD/L corresponding to 107 % increment as compared to the VFA concentration in the influent. However, as HRT increased VFA concentraiotn was decreased to 143±552 mgCOD/L at HRT of 8 days. The reduction rates of total solids were 12.2, 26.5, 24.8, and 43.0 % for HRT of 2, 4, 6, and 8 days. As HRT increased the hydrolysis of organic particulate matters in the reactor was enhanced due to the increasing of solids retention time in the baffle zone with low upflow velocity in long HRT condition. Consequently, we found that a primary sludge became a good source of VFA production by the application of ABR process with HRT less than 4 days and the 12-26 % of total solids reduction was expected at these conditions.

The image-to-image translation is one of the deep learning applications using image data. In this paper, we aim at improving the performance of object transfiguration which transforms a specific object in an image into another specific object. For object transfiguration, it is required to transform only the target object and maintain background images. In the existing results, however, it is observed that other parts in the image are also transformed. In this paper, we have focused on the structure of artificial neural networks that are frequently used in the existing methods and have improved the performance by adding constraints to the exiting structure. We also propose the advanced structure that combines the existing structures to maintain their advantages and complement their drawbacks. The effectiveness of the proposed methods are shown in experimental results.