2. The sludge sedimentation performances pretty good; its excess sludge quantity much less than the traditional activated sludge process.
3. Its power of resistance against the quality and quantity of water change’s impact is strong, it is flexible to operate; When water fluctuation is larger it is had better consider to set up regulation pool.
4. It is not easy to happen the sludge expansion and the facilities that sewage treatment plant equipped are comparative less on the type and quantity. Also the control system is simple, safe and reliable of operation.
5. Getting higher volume utilization; the whole system runs in a pushing streaming way, while the reaction zones are in the form of completely mixed operation, in order to realize the synchronization of carbide and nitrification - denitrification function to improve the ability of removing organic matter.
6. CASS is continuous with inflow water, the inlet pipe road needs without control components such as solenoid valve, its single pool can run independently; the technological process is simple, the layout is compact, the investment is low and the automation in a high degree.
7. In the pool aeration is cyclical, also there exists changes in the concentration of dissolved oxygen, and the oxygen concentration gradient is so large which can lead to high transmission rate that energy saving effect is remarkable [2].
After determining the main body structure, then according to the original data and conditions as follows:
item    Chemical
Oxygen Demand    Biochemical Oxygen Demand    Suspended solid
Inflow
water quality
（ ）
1200    700    500
Effluent water quality（ ）
≤100    ≤30    ≤100
(The COD, BOD values in inflow water are relatively high, so the urban sewage ought to be mixed with certain volume industrial waste water)
On the basis of getting know with textbook again and check data seriously, and combining with the specific design requirements, in succession to determine the grille that used to remove large volume of waste, settling equipment, the second sedimentation pond to get rid of the water suspended solids and deactivation activated sludge produced after the process of biochemical treatment. In order to guarantee the final sludge got treated completely on a largest extent, setting up a belt type filter press. The recycling water up to standard can be directly get an available used in the corresponding place in factory results in achieving the best combination of decontamination, environmental protection and economy.
There is putting forward a variety of solutions to this treatment process design .under the repeated comparison, finally determine an optimal solution.
Grille - pumps - fine grille - regulating reservoir - flat flow grit chamber-Cyclic Activated Sludge System pool - the second sedimentation pond - concentrated tank - clear water reservoirs [3] (Note: SBR process characteristics show that it can set without the  primary settling tank and the second sedimentation pond, but there is no one processing structure to remove in water with a great quantities. So considering set a to remove Suspended Solid and deactivated sludge produced through biochemical pool effectively. In addition the sludge from second sedimentation pondcan back into the biochemical pool, raising its sludge load, which achieve a virtuous circle.
The design’s whole budget including fixed assets (land charges+ structure engineering cost, construction fee + the cost of equipment)plus operating cost (salary and welfare +expenditure on power wage+ production water cost + transportation cost + maintenance charges), the total investment cost is RMB 63.079 million. Among them tooling plant takes up more, the operation cost is RMB 2.406 million.
Keywords:  Urban wastewater；High biological availability；Sequencing Batch Reactor；Intermittent operation；Economy；Cyclic Activated Sludge System 城市污水SBR生化处理工艺设计+CAD图纸+答辩PPT(3):http://www.751com.cn/huaxue/lunwen_4497.html