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%.

Scale formation is inevitable problem when seawater is treated by vacuum membrane distillation. The reason is the high concentration of calcium ion(Ca2+), sulfate ion(SO4 2-) and bicarbonate ion(HCO3 -). These ions form calcium sulfate(CaSO4) and calcium carbonate(CaCO3) on the membrane. The scale formed on membrane has to be removed, because the flux can be severely reduced and membrane wetting can be incurred. This study was carried out to investigate scale formation and effectiveness of acid cleaning in vacuum membrane distillation for SWRO brine treatment. It was found that permeate flux gradually declined until volume concentration factor(VCF) reached around 1.55 and membrane wetting started over VCF over 1.6 in the formation of precipitates containing CaSO4 during VMD operation. In contrast, when calcium carbonate formed on membrane, permeate flux was gradually reduced until VCF 3.0. The precipitates containing both CaSO4 and CaCO3 were formed on the membrane surface and in the membrane pore.

선박에 주로 사용되는 기존 해수담수화 공정의 경우 많은 에너지가 소모 된다는 단점이 있다. 막증발법(MD)은 유입수의 삼투압으로 인한 구동력의 저하가 역삼투공정에 비해서 낮은 장점을 가지며, 비교적 낮은 온도(60 ∼ 80℃)에서 운전 가능하기 때문에 선박의 엔진 폐열, 해수열원 등을 활용하여 운전 비용을 절감할 수 있다. 본 연구에서는 실험실 규모의 진공식 막증발 장치에서 도출된 조건을 바탕으로 3 m3/일 규모의 실제 VMD 파일럿플랜트를 설계 및 제작하여 성능을 평가하였다. 운전결과, 3～5 L/㎡-hr의 플럭스와 99.99%의 염제거율을 나타냈다.

In this study, the performance experiment was conducted to compare the permeate flux of hollow fiber Vacuum Membrane Distillation module according to leak problem between module housing and membrane bundle. For the permeate flux performance experiment of the two Vacuum Membrane Distillation modules, the Lab-scale experimental equipment was built in the capacity of 1㎥/day. The performance test of the two Vacuum Membrane Distillation modules were analyzed according to the feed water conditions. As a result, it was analyzed that the leak VMD module decreased about 14% of permeate flux than normal VMD module.