Research on the Removal of Wastewater and Microorganism in A~2 / O Process at Low Temperature Conditon
|School||Harbin Institute of Technology|
|Keywords||A ~ 2 / O process Biological Nutrient Removal Hypothermia Composite Process Microorganism|
Songhua River is an important river, occupies an important position, and the its tributaries - Feiketu River, one of its main sources of pollution in the watershed management. With economic development, the River Basin Feiketu the industrial enterprises gradually increased, the formation of the industrial park, and its emissions of pollutants seriously exceed Feiketu River assimilative capacity. Specific low temperatures for the northern, expand the industrial park wastewater treatment technology research and analysis of low temperature sewage simultaneous nitrogen and phosphorus removal mechanism to determine the characteristics of microbial populations to change the status quo of the frozen period which enjoys a the Ketu river pollution, and thus protect the Songhua River water quality safety. The test first study sludge reflux ratio, nitrification liquid reflux ratio, MLSS, SRT and DO parameters A ~ 2 / O process nitrogen and phosphorus removal. In the return sludge in the ratio of 50%, the nitrification liquid reflux ratio of 300%, MLSS between 2.5 ~ 4g / L, DO is maintained at 3 to 4mg / L and SRT control in the case of about 15d, room temperature system (A), the temperature is maintained 23 ± 1 ℃, can achieve good synchronization of nitrogen and phosphorus removal, the average effluent COD, TN and TP concentration from 25.18 to 30.21 mg / L, respectively, 10.09 to 12.59 mg / L, 0.15 to 0.28 mg / L ; cryogenic system (B), maintaining the temperature of 12 ± 1 ℃, phosphorus removal works well, but denitrification poor average effluent COD, TN and TP concentration in 27.21 to 32.19mg / L, respectively, 16.91 to 20.89 mg / L, 0.20 ~ 0.31 mg / L. Under low temperature conditions (12 ℃), microorganisms, especially the activity of nitrifying bacteria lower metabolic capacity is weak. So take dosing filler strengthen measures to increase the number of micro-organisms in the system, fixed nitrifying bacteria. The composite A ~~ 2 / O system (B) The results show that, the TN removal rate increased by 20%, effectively improve system processing effects. On this basis, in order to further reduce the nitrification effluent TN by changing the sludge recycle ratio, increasing the sludge back into the aerobic tank, the strengthening of nitrifying bacteria make it a long period under aerobic conditions, to maintain its efficient activity . The results proved that this way can achieve good effect of nitrogen cryogenic system, the water reached the national level A emission standards. At room temperature system (A) during the stable operation of the microbial intracellular PHAs and poly-P granules staining, intuitively understanding the mechanism of biological phosphorus removal. Means microscopy and scanning electron microscopy (SEM) observed at room temperature, cryogenic system microbial community succession rules and differences, sludge characteristics. Found by microscopic examination, the two systems are very rich microflora, the food chain is longer, to ensure the efficient and stable operation of the system. Direct cause found by scanning electron microscopy room temperature relatively dense sludge low temperature sludge loosely, patchy distribution, which is a low temperature, the the sludge adsorption settlement performance is poor. When the the system sludge load is low or when a sudden cooling system sludge bulking phenomenon by increasing the amount of aeration, to guarantee continuous access to water and other measures to control sludge bulking. The cryogenic system (B) to achieve good synchronization nitrogen and phosphorus removal, breaking the synchronization constraints A ~ 2 / O process can not be achieved, breaking the temperature limit of its treatment effect of China's industrial park wastewater treatment facilities winter Run the important guiding significance. Test results as a demonstration project design and operation, regulation reference. Composite process and the dual means changing the recirculation mode for nitrogen and phosphorus removal under low temperature conditions and the old sewage plant is facing a transformation to provide technical support.