Chemical Deoxygenation Method Of Diffuser Oxygentransfer Measurement And Application

At the end of Mar.2014, China has built about 3622 sewage treatment plants in urbans and cities, whose capacity is about 153 million m3/d. Assuming that the energy consumption per ton of wastewater is 0.20-0.35 kWh, the national urban sewage treatment energy consumption is 0.30-0.54 million kWh/d. As aeration system is a part of the construction of sewage treatment plant, equipment and installation cost is not expensive. Although it is the main energy consuming unit of sewage treatment process, the consumption is about 50%-60% in total energy.Nowadays in China we use "Oxygen transfer measurement of aerators in clean water" (CJ/T 3015.2-1993) as our standard. And we use "Specifications for environmental protection product - Middle and fine bubble diffusers" (HJ/T 252-2006), " Corundum fine bubble diffuser for water and wastewater treatment " (CJ/T 263-2007) and " Membrane fine bubble diffuser for water and wastewater treatment "(CJ/T 264-2007) as limitation standards. Thanks to the development and progress of sciences and technologies, the existing equipment performance has exceeded the standard requirements. There are no effective methods for the detection of the aeration devices, which make a large number of low performance, high energy consumption and short-life productions. Therefore, it is necessary to optimize and modify the existing test methods and revise the standard limitation systems.We have built an aeration testing platform considering domestic sewage actual conditions, aiming at chemical deoxygenation method optimization and limits value of standard revision work. And The main contents and results are as follows.1. Combined with the diffuser oxygen transfer measurement standards, testing platform designation and usage situation, we tested aeration oxygenator performance engineering scale as our purpose, using the mature and advanced aeration oxygenation methods and technologies. A set of aerator test platform has been built in Shandong Province, which includes test pool, air flow control system, water level control system, detection of dissolved oxygen device, PLC control module, the pressure test device, dosing device. The the testing cylindrical tank is 5m diameters and 10m depth, which can meet the needs of the engineering scale test, and it has obtained the CMA qualified certification.2. In order to improve the accuracy, stability and guidance of aeration product testing, the conditions of the aeration device are more close to the actual working conditions. The test method is more general, accurate and fast. The main researches and improvements include the following three aspects.(1) Linear and non-linear regression methods are used to process the data. The linear regression method used to determine the end of the test is 6/kLaT, while the non-linear regression is 4/kLaT. So we use time-effective non-linear regression to process the data.(2) The validity of the data in the original test method were modified. The error of the kLaT value and the mean value of the test points in group 1 was less than ±5%, otherwise, the test should be redone. Corresponding to the three or more different ventilation test sotr values in group 1, test linearity value R2 is equal to or larger than 0.99, and the test results are available; otherwise the test should be repeated another 3 times or more under the same conditions. And the kLaT values error should be less than±10%.(3) We modified the original calculation of Cs,20 substitution fixed value 9.17mg/L. With reference to international standards, the Cs,2o was accurately calculated.3. The standard limited value of the oxygen aeration performance test is determined. The standard oxygen transfer rate (SOTR) is not required, and the standard oxygen transfer efficiency (SOTE), the specific standard oxygen transfer efficiency (SSOTE), the theoretical aeration efficiency (E) and other parameters are regulated.We have set up a suitable sewage treatment aeration technology requirement and test standard system in Shandong province. It will further standardize the province aerator market, and provide more accurate and effective data for engineering design, guide efficient energy-saving aerator. And it can lay the technical foundation in Shandong province to process industry energy and saving-technology improvements.