The point-of-use water dispenser systems are widely used because of convenience in handling and demand for high-quality drinking water. The application has been increased recently in the public places such as department stores, universities and the rest areas in express ways. Improvement of water qualities by the dispenser systems was compared with tap water in this study. The tap water is supplied to the dispenser as the influent of the dispenser system. The twelve dispensers in the public places were used. The five dispensers used reverse osmosis as the main filter and other dispensers used various filters such as ultrafiltration, nanofiltration, and alumina filter. The water quality indicators for sanitation safety, i.e., turbidity and total coliforms, were evaluated. Other water qualities such as pH, residual chlorine, heterotrophic plate count (HPC), and total cell counts were also analyzed. By the point-of-use water dispenser, the turbidity, residual chlorine and pH were decreased and the HPC and total cell counts were increased. The t-test results revealed that the HPC of the tap waters were not significantly different from the treated waters but the total cell counts of the two groups were significantly different. The low pH of the RO filter treatment was also significantly different from the tap waters. This study will contribute to understand the role of the point-of-use water dispenser in improving water quality and to identify key water quality for the proper maintenance of the dispenser systems.

In this study, thermal performance test of VMD module was performed, prior to the construction of the demonstration plant using the vacuum membrane distillation　(VMD) module of the capacity of 400 m3/day and to the commercialization of the VMD module. For the thermal performance test, the experimental equipment of capacity of 2 m3/day was constructed. The permeate flux test and thermal performance test according to feed water conditions such as temperature and flow rate were conducted. The VMD module used in the study was manufactured by ECONITY Co., LTD with PVDF hollow fiber membrane. As a result, the Performance Ratio (PR) of the VMD module showed the maximum value of 0.904 under the condition of feed water temperature of 75℃ and flow rate of 8 m3/h. PR value of the VMD module using PVDF hollow fiber membrane showed linearly increasing relationship with feed water temperature and flow rate. Also, The permeate flux of the VMD module was analyzed to have maximum value of 18.25 LMH and the salt rejection was 99.99%.

본 연구에서는 공급수의 Blending 및 ERD 적용을 통해 역삼투 공정의 소비전력량을 비교 분석하였다.

In this study, the actual energy consumption of the secondary side of district heating system(DHS) with different hot water supply temperature control methods are compared. Two methods are outdoor temperature reset control and outdoor temperature predictive Control. While outdoor temperature reset control has been widely used for energy savings of the secondary side of the system, the results show that outdoor temperature predictive control method saves more energy. In general, outdoor temperature predictive control method is lowering the supply temperature of hot water, and it reduces standby losses and increases overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, outdoor temperature predictive control method saves about 19.1% when it compared to outdoor temperature reset control method. Also, it is found that when partial load condition, such as daytime, the fluctuation of hot water supply temperature with outdoor temperature reset control is more severe than outdoor temperature prediction control. So, it proves that outdoor temperature prediction control is more stable even at partial load conditions.