Research On The Application Of Anaerobic Process In Low-concentration Waste Water Treatment

The proportion of sanitary sewage among sewage discharge from the whole society is 60%. Although a great amount of wealth and labor has been spent into waste water disposal in cities and towns by the government, few benefits have been achieved. Approx.25 billion tons of sanitary sewage will be discharged every year, and 15 billion RMB will be spent by means of traditional process to dispose the sewage per year. The thesis concentrates the condition mentioned above and represents a feasibility study on the application of anaerobic process with low investment and low energy consumption in sanitary sewage disposal.In practice, anaerobic applied in low concentration sewage disposal is not taken as a late model science, and it has been carried into execution in many regions abroad. From the beginning of anaerobic developing to the invention of specific and high efficient anaerobic reactor at present, anaerobic is applied in low concentration sewage at all times. Domestic embedding disposal process with free energy is a new ABR bent plate anaerobic reactor to dispose sanitary sewage in fact.Meitan County Municipal Sewage Disposal Project is taken as the pilot base in the thesis. High efficient anaerobic reactor + short range nitration treatment process are applied in this pilot base. During commissioning and after normal start up, anaerobic process is controlled manually in multi direction, the factors influenced on anaerobic in low concentration sewage disposal are obtained. Adding catalysts and keeping fine earth water mixing condition to defeat the faults caused by normal temperature of raw water and achieve a good result.In the duration of pilot testing, metallic element catalysts and dosing methods, mixing intensity, load variation, alkalinity and temperature are put into test, and removal efficiency and the curve of these contributing factors are obtained respectively.Kinetic model of anaerobic reaction and calculation model of UASB reactor also have been put forward in this thesis. And according to anaerobic dynamics and plug flow reactor, the engineering calculation equation is advanced. After the basis data is inputted with reference to all kinds of data which is suitable for pilot test, all the data of reactor used for engineering purpose can be obtained.Anaerobic effluent can't accord directly with the relevant national standards and need to be treated by 2nd grade oxicly biologic and chemical way. Traditional SBR, oxidation ditch and biologic catalytic oxidation all can be regarded as the follow-up treatment process for anaerobic effluent, but load of the reactor should be adjusted and functions should be districted and nitration reaction should be strengthened in order to decrease investment and operation expenses.As for pilot test sewage treatment plant with the daily capacity 5000m3/d, economic analysis of capital assets and analysis of actual operation expenses is made and economic budget under the most unfavorable condition is also performed in this thesis.Through a series of test and model derivation, it shows that it's absolutely feasible for high-effective plug flow anaerobic reactor to deal with low-concentration waste water similar to domestic sewage. This treatment also has the huge advantages in economy and management. For purpose of reaching this effect and reflecting these advantages, some engineering suggestions and start-up precautions for anaerobic reaction in low-concentration waste water treatment are also presented in this thesis.