Fabrication Of Fiber Reinforced Hollow Fiber Ultrafiltration Membrane Module And Its Application In Water Purification

Hollow fiber ultrafiltration membrane has the advanteges of high packing density,good water quality and easy operation in the field of water treatment. However, the membrane is prone to being fouled and with poor mechanical property, which severely limits the application of the membrane. Thus, in this study, reinforced PVDF hollow fiber ultrafiltration membranes with strong mechanical strength were prepared with different forms of membrane modules. The water quality and antifouling properties of different forms of membrane modules were comprarely studied in wastewater treatment. The shortcoming of the weak interfacial bonding force between surface membrane layer and inside supporting body was also discussed. Methods to improve the interfacial bonding strength were proposed.The best formula of membrane casting solution is PVDF 16%, PVP3%, PEG4%,DMAC77%, which the resulting membrane has good mechanical strength and water flux with 319cN tensile strength and 864L·h-1·m-2·bar-1 pure water flux. The reinforced hollow fiber ultrafiltration membrane was prepared based on the formula, which the influence on membranes by tensile machine speed, metering pump speed and wire wheel speed were optimized in membrane producing process. The result showed that the best operation parameters of production equipment: the tensile machine speed was 43 r/min, the metering pump speed was 18 r/min, the wire wheel speed was 15 r/min.The reinforced PVDF hollow fiber ultrafiltration membrane and homogeneous hollow fiber membrane were both assembled into U-type membrane module and seaweed-type membrane module. They were operated in the same membrane bioreactorunder the same circumstance conditions to compare the effluent quality, antifouling performance, and operation life. The result showed that the membrane withseaweed-type module has better antifouling performance and longer operation life. The reason was that the seaweed- type module has larger range of swinging and shaking, which can decrease the formation of cake layer. Also homogeneous membranes have poor antifouling performance and short operation life.Due to lacke of bonding strength between the membrane layer and polyester filament supporting body, membrane often peels from polyester filament in the practical application.So measures were carried out to modify the polyester filament, which caused the hydrophilic polar group hydroxyl and carboxyl group to grow in the surface of polyester filament. These groups could significantly improve the hydrophilic property and enhance interfacial adhesion between the surface membrane layer and polyester filament. After modification, the pull-out force between the membrane layer and polyester filament increase to 206.37N.