The sewage treatment plant is designed for the capacity of 43,000m3 per day which about 70% of its is domestic sewage,the main pollution indicators: CODcr, BOD5, SS, NH3-N, P. The consideration of  influent water according to followings: CODcr: ~ 220mg / L, BOD5: ~ 110mg / L, SS: ~ 220mg / L, NH3-N: ~ 35mg / L, P: ~ 4mg / L.Domestic sewage treatment technology and economy are feasible, effluent is discharged into the river nearby, its quality carry out the first standard(B) of"urban sewage treatment plant pollutant discharge standard" (GB 18918-2002: CODcr: ≤ 60mg / L, BOD5: ≤ 20mg / L, SS: ≤ 20mg / L, NH3-N: ≤ 15mg / L, PH: 6 ~ 9, P: ≤ 1mg / L.
The principles of sewage treatment project determination:
(1)  Reliable basic data. Study basic materials and basic data carefully ,  analyse the various influencing factors comprehensively,  fully acknowledge the characteristics of sewage quality and geography, choose reasonable design parameters for the project to provide a reliable basis.
(2) Reasonable site selection . According to the overall plannings of urban and drainage engineering combining with the terrain, weather conditions ,we should select the site of have better building conditions and environmental impact through a comprehensive analysis and comparison
(3) Advanced and practical technology . Selecting the advanced, stable,reasonable investment and handling costs sewage treatment processes, using of the proven effective new technologies, new processes, new materials and new equipments actively and cautiously which made sewage treatment process advanced and reliable,effluent can reach The stability of discharge standards
4) Thoughtful general arrangement . According to the process and the functional requirements of buildings and structures, , combining Changzhi topographical, geological and climatic conditions, fully considering the requirements of construction, operation and maintenance , coordinating the relationship layout among plane、elevation and pipeline, to strive for perfect overall layout.
(5) Avoid secondary pollution. As a environmental engineering, should avoid or minimize adverse effects on the environment, such as odor, noise and solid waste ; Properly dispose of gate residue, grit, sludge and odor etc generated in the process to avoid secondary pollution to the environment.
(6)Convenient operation and management. People-oriented, fully consider the measures easy to the plant operation and management .Automatic control in its process should strive to safe, reliable, economical and practical which facilitate the management , reduce labor intensity and operating costs.
(7)Combine recent with future. The plant should be overall designed both short term and long term, its area should be controlled according to the general scale, and make arrangements for phased construction, rationally determine the recent scale.
(8) Meet security requirements. The design of the plant should takes full account of the requirements of safe operation, as setting appropriate persion facilities, beyond pipelines. The design of fire control and digester, cylinders and other dangerous elements in plant shall be designed to comply with the appropriate safety design specifications.
According to the design principles and the main pollution indicators selected program processes and procedures, the project design uses Orbal oxidation ditch process, oxidation ditch process Aubert stable, water quality is good, not only to meet the BOD5, SS emission standards, but also the effect of nitrogen and phosphorus removal can be achieved, with a certain resistance to impact load; through Orbal oxidation ditch process, less its residual sludge, digested sludge is not easy to dehydration, sludge treatment costs are lower. Design of this project process: coarse grid, improve pumping stations, fine grid, advection grit chamber, anaerobic tank, Aubert oxidation ditch, two clarifiers, ultraviolet disinfection drainage. After the treatment process, the effluent quality can achieve the following objectives: BOD5: 14.46mg / L, CODcr: 44mg / L, SS: 11mg / L, NH3-N: mg / L, TP: 0.8mg / L. 城镇生活污水处理厂工艺设计+CAD图纸+高程图(2):http://www.youerw.com/huaxue/lunwen_4507.html