poly (vinyl alcohol) ( PVA） As a kind of important industrial raw material, has excellent physical and chemical properties, are widely used in coating, adhesive, paper processing agent, emulsifier, dispersant, and thin film products such as production, range of application in textile, food, medicine, construction, wood processing, paper making, printing, agriculture, steel and polymer chemical industry, etc.
In recent years, the world especially in China's textile industry, high-grade paper industry, oil industry and the rapid development of automobile industry and construction industry, driving the surge in PVA production capacity. According to statistics, in 2005 the total output of PVA for 138. 00000 t, 2013 to 213. 30000 t, of which China accounts for about 26. 82%. PVA industry in our country after more than 40 years of development, has become the world's largest producer of PVA and PVA production capacity in China in 2016 to 124. 60000 t, accounting for more than half of world output can. From the perspective of the industry demand of PVA, the largest is the polymer additives and fabric paste production industry, 38% and 20% respectively. Predicts 2020, the total demand to reach around 80 of PVA. 00000 t, about 48 of total global demand. 48%.
PVA can cause pollution to the environment, not because of its toxicity ( Its itself is nontoxic) , but because of its biodegradation. The larger surface activity can make the polluted surface water bubble increased, viscosity increased, reoxygenation behavior is extremely unfavorable for surface water, thus inhibiting aquatic respiration activity. In addition, with PVA wastewater discharged into water body will promote the rivers, lakes and the release of heavy metals in Marine sediments and migration, enhance its activity, cause more serious environmental problems.
At present, the commonly used of PVA wastewater treatment methods mainly include physical and chemical method, biological method and their combination process. Chemical method is first used in PVA wastewater treatment, such as chemical coagulation method, so far, more than 30 years; After 2000, flocculation process and advanced oxidation technologies have became a research hotspot; In recent years, the pva water soluble film separation technology in the treatment of the emergence of pva wastewater. As people the deep study of physical and chemical method, its brings the problems such as high cost and secondary pollution is becoming more and more highlighted. Therefore, many researchers have been focusing on biological treatment of wastewater containing PVA and combination process, especially from 2005 after gradually become a hot research topic. The author based on the literature at home and abroad, pva water soluble film systematically summarizes the status of pva wastewater treatment; At the same time, combining with the existing operation of the project cases, discusses the possible problems of PVA wastewater treatment technology and the future development trend.
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