Filtration Of Printing And Dyeing Wastewater By Ultrafiltration Equipment

　　 [student problem] ultrafiltration equipment filter Printing and dyeing wastewater?

[solution] printing and dyeing waste water There are many methods, and biochemical method is the most widely used method. There are mainly two kinds of process flow: the first is the biochemical process as the main body, and the physicochemical method as the preprocessing multistage processing flow; the two is the multi-stage processing flow with the materialization method as the main body. After dyeing and printing wastewater was treated by conventional method, the chromaticity decreased to some extent with the removal of BOD and some suspended solids. However, the treated wastewater still had a deeper color, which was unfavorable to discharge and reuse, and further decolorization was necessary.

With the development of dyestuff industry and the progress of printing and dyeing technology, the chemical structure and color stability of dyes have been greatly improved, which has increased the difficulty of physical and biochemical treatment. If ultrafiltration membrane is used to filter printing and dyeing wastewater, according to the type, molecular weight, aggregation state and water solubility of the dyes in the waste water, a good filtration effect can be achieved as long as the membrane material and the molecular weight of the filter are selected properly, so that the dye can be recovered and utilized.

As early as 80s of last century, the cyclization Institute of the Chinese Academy of Sciences carried out an industrial trial on the treatment of vat dye wastewater with the Beijing Guanghua dyeing and weaving factory. A 3. 6rri2 external pressure polysulfone ultrafiltration device was used. Under the conditions of inlet pressure of 0.22 0.24kPa and liquid temperature of 55 40~, 2000h was run, 617m3 of ultrafiltration dye wastewater was recovered, 1036kg of vat dyes was recovered, the flux of ultrafiltration membrane was 20.30U (.H), the decolorization rate was 95%~98%, the COD removal rate was 60%~90%, and the dye recovery rate was greater than that of 95%~98%.

　　 Ultrafiltration desizing wastewater Technology

After filtration, it is sent into the ultrafiltration device through a buffer tank. Ultrafiltration usually has three sections. The concentration of PVA in the concentrate is increased to 8% 1 14%. The concentrated slurry is stored and returned to the slurry tank, and then used in the sizing process with the original slurry (including PVA10%~16%). Ultrafiltration contains about 0.1% of PVA through water, which is used for desizing and rinsing through water, thus reducing the consumption of supplementary water and heat.

Ultrafiltration desizing wastewater has been widely applied in foreign countries. At home, there has been industrial experimentation and research in this area. For example, the Xiangtan dyeing and printing plant introduced a set of PVA ultrafiltration equipment with 2m3/h capacity from Japan, and carried out the industrial test of the desizing wastewater recovery. The test results show that the device can concentrate PVA wastewater with a concentration of 0.5%~1.0% to PVA concentration of about 10%. The removal rate of PVA in water was higher than that in 95%.. Tianjin University of Technology used the self-made SPES/PES -C hollow fiber ultrafiltration membrane module to carry out the concentration test of desizing wastewater. The molecular weight of the membrane was 20000., the PVA content in the liquid (wastewater) was 0.1%.0.5%, and the temperature was 80 - 85 degrees Celsius. During operation, the ultrafiltration population pressure 0.2MPa and outlet pressure 0.05MPa. results that when the concentration of PVA in waste water is concentrated from 0.5% to 4.5010, the membrane flux decreases from 82U (n12.h) to 34U (IT12.h).

The above contents are compiled according to the problems encountered by the trainees in actual work, for reference. If there are any problems, please communicate with them in time.