| During recent years, with the improvement of people's living standard and rapid development of industry , the releasing amount of domestic and industrial wastewater has been increasing, and current sewage treatment equipment hasn't been meeting present discharge demand of wastewater , which has caused severely environmental pollution and shortage of water resource. Therefore, developing new sewage treatment equipment with high efficiency and low expense is extremely urgent. Sewage biological treatment technology which has been existing 100 years so far is the most economical and efficient approach among municipal and degradable industrial sewage treatment due to its high removing ratio of organic material and low running cost. Biological process used for wastewater treatment can be divided into two main categories: attached growth and suspended growth process. The former is known as bio-film process, in which microorganisms are attached to some medium. The latter is known as activated sludge process, in which microorganisms are maintained in liquid suspension. But principal disadvantages claimed for conventional activated sludge process are as follows: lager space requirement, high cost of construction and running, complex management, worse recovery from shock loads, readily occurring bulking sludge, the limit ability to remove nutrients, such as N,P. Bio-film process acted as biological treatment developed simultaneously with activated sludge is not only used for secondary biological treatment instead of activated sludge process in most circumstance, but also has some unique advantages, such as diversity of microorganisms participated in treating wastewater and long food chain , greater process stability, less equipment maintenance needs, less energy required, better recovery from shock loads, less residual sludge , no problems of bulking sludge , the ability of nitrification and denitrification. But biofilm process also has some shortages. The application of highly efficient biological fluidized-bed process is limited, because the biofilm attached to the carrier, fluidizing starting, recovery after cutting electric power and water supply are difficult, and power required for fluidizing is great when the density of biological carrier is big, biological carrier will float on the surface when their density is small. Cyclic activated sludge-biofilm technology (CAS-BT) is a sort of new wastewater treatment composite technology of activated sludge-biofilm. Based on referring and assimilating advantages of activated sludge and biofilm process, the technology is developed through bringing the bio-carrier developed by ourselves into the CAST. Each basin of CAS-BT comprises biological selector and composite reaction zone. This process assimilates the advantages of activated sludge and fluidized-bed biofilm process, simultaneously overcomes each shortages and exists cooperation with different specific microbial species in a way. Therefore , CAS-BT is a new wastewater treatment technology which has competition in the aspect of technology and economy, suiting the situation of our country.CAS-BT experimental model was made, adopting light porous biology carrier(suspended stuffing) developed by ourselves, starting with from increasing biomass and enhancing rate of mass transfer. Simulating experiment was conducted in the CAS-BT experimental model to analyze removing characteristics of organic material treat in the beer wastewater and obtained a great deal of fundamental data. CAS-BT experimental model is made of plexiglass. Total volume of reactor is 60 liter. The reactor consists of biological selector and main reactor. The former is divided into 4 sections , the volume of per section is 2.5 liter, total is 10 liter, being 17 percent of total volume of reactor. The volume of the latter is 50 liter, which occupies 83 percent of total volume of reactor. Loop aeration pipelines are laid on the bottom of the main reactor. Air diffuser adopts porous stone aerator. Aerating system consists of air c...
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