Instruction：Because of the fast development of city life, emissions levels grow with each passing day, its composition is also more and more complex, large discharge of sewage in the water environment pollution and water resource availability is reduced, the sewage treatment rate is generally relatively low, some places even untreated sewage directly discharged into the environment. According to the China Environmental Protection compendium of distant view target requirements, municipal and town sewage. The average treatment rate of not less than 50%, city of not less than 60%, key city of not less than 70%. Various types of sewage in accordance with the "integrated wastewater discharge standard" requirements, in order to meet effluent discharge standards, the vast majority of urban sewage treatment plants must be in the two stage biochemical treatment and advanced treatment technologies.
Precursor of sewage treatment is to master the wastewater composition, the important factors that influence the substances on the environment, the composition of sewage and its complex, very difficult to single index to show its properties. Therefore, in the water quality index of many impurities, according to the size and shape of sewage into the suspended matter and dissolved substances in two categories, each type according to their chemical properties into inorganic and organic matter: according to dissolved oxygen consumption in water and pided them into biochemical oxygen demand (BOD), chemical oxygen demand (COD). This index is the most used in sewage treatment, the design of the sewage treatment plant influent quality, COD were 210mg/s, 380mg/s, when the ratio of BOD and COD said the biodegradability of wastewater, the ratio is greater than 0.3 when can think better biodegradability poor biochemical, less than 0.3. The design of the ratio of BOD and COD is greater than 0.3, good biodegradability, can adopt the processing method of biochemical treatment.
The object of the sewage treatment plant processing is secondary urban sewage, sewage average daily volume of 160000 tons, built sewage plant type for the large-scale sewage treatment plant, the treatment with oxidation ditch process the sewage oxidation ditch process, there are many advantages, simple process flow, less structures, construction cost, good treatment effect, it has the function of stable nitrogen and phosphorus removal, have the ability to resist impact load, organic matter can not easily degraded, less sludge production, advanced technology and mature, maintenance is simple, easy to get the domestic engineering management experience, good water quality. Before the biochemical process, you should also set the primary treatment, primary treatment by physical methods, the sieve trapping method, the grill is arranged on the suspended matter and floats the water interception, to reduce the pump and the subsequent biochemical treatment unit load; gravity separation method, setting sand pool to remove inorganic particles in sewage density larger under the action of gravity, the design is aerated grit chamber, only the content of organic matter in the pool of around 5%, but also to the aeration effect on sewage water. Primary treatment for the removal of suspended solids. Because this design using oxidation ditch, so without primary sedimentation tank. Two levels of processing, design of oxidation ditch, I used the Carrousel oxidation ditch six corridor, it is a kind of modified activated sludge, the continuous reaction pool with a biological reaction tank. The mixture of sewage and sludge in the reactor to a closed type aeration channel continuous cyclic reaction, the single channel width of 10 meters, the straight part of the length of 100 meters, the oxidation ditch wall thickness of 0.25 meters, a total of 4. Convergence in the oxidation ditch after flow type two sedimentation tank, with peripheral inlet and outlet layout, the 45 m pool, pool equipped with ZBGN-45 type mud scraper, two sedimentation tanks a total of 4, scraping mud machine 4 sets. And then set the ultraviolet disinfection pool, disinfection of water, ultraviolet disinfection equipment by TR0JAN company in Canada UV4000PLUS production equipment. Two sedimentation tank in sewage and sludge, sludge, enrichment of the pollutants in sewage, in addition to containing ash and large amounts of water (95% ~ 99%), also contains plenty of organic matter, microbes, bacteria, parasite eggs, volatile substances, heavy metals, salts, a plant nutrients (nitrogen, phosphorus, potassium) etc.. Its huge volume, and easy to corruption stinks. So to handling and processing, in order to prevent pollution two. Sewage plant concentrated sludge gravity thickener, make water sludge concentration was 97% (concentration is 99.2%). After the sludge dewatering, sludge cake sinotrans. 城镇生活污水的处理工艺设计+CAD图纸+答辩PPT(2):http://www.youerw.com/huaxue/lunwen_6900.html