Process Features of CAST Wastewater Treatment and Its Application in China

Abstract

CAST, an advanced process of wastewater treatment, has achieved great attention and application. This paper gives an overall introduction on CAST development, principles, features and its current application and research in China. This paper focuses on comparison CAST with SBR, the traditional process, and describes its advantages in details. Then the paper summarizes the current research and the existing problems, lastly, makes a prospect for the future application of CAST process. Instroduction Wastewater plays an important role in environment pollution. In various wastewater treatment technologies, sequencing batch reactor (SBR process) is the earliest with advantages of easy con- struction, stable operation and high removal efficiency and disadvantages of not continuous flow, not suitable for processing large amounts of wastewater and complex management of batch opera- tion. In recent twenty years, with the development of automatic control technology, SBR process has attracted attention and research and a series of new improved process has been developed with some typical SBR deformation process including ICEAS,CASS(CAST), DAT-IAT, UNITANK(Zhou, A.L. & Niu. Y. J. 2010 ). CAST process with full title cyclic activated sludge technology, is a new SBR deformation pro- cess based on ICEAS and introduces in China at the beginning of 1990s. Through many years of re- search and practice, it has development into a mature wastewater treatment process. In combination of reaction, precipitation and drainage function, the pollutant is degrading in the whole process of reactor. Microorganism is in the periodic change of aerobic, anoxia and anaerobic. So the reactor realizes pollutants removal, like COD and nitrogen and phosphorus(Zhang,L. & Wang S.P., et al. 2010). More virtues include good effluent quality, strong adaptability to shock load and good acti- vated sludge, which effectively overcomes problems of sludge expansion, low investment and small occupation area. The high efficiency of CAST process confirms to China's situation and achieves wide promotion. Currently, it has applied into wastewater treatment in industries like domestic wastewater, brewery, pharmacy, chemistry, dyeing, food and butchery(Zou B.H. & Wang H.B.2012).