The Biological Purification Technology Of High Concentration Ammonia Nitrogen Wastewater

The control of ammonia nitrogen has become the key to improve the water quality since the phenomenon of serious pollution of ammonia nitrogen. Both physicochemical and biological methods are used to reduce ammonia concentration. Due to the limitations and shortcomings of the physicochemical methods, biological denitrification is often used in the deep treatment process. The traditional biological denitrification is the process that the nitrogenous compounds transformed into nitrogen by nitrification and denitrification using denitrification microorganisms. Nitrifying bacteria are generally autotrophic aerobic while denitrifying bacteria are anaerobic heterotrophic. Because of different conditions, two different systems are needed. Besides, the whole process is too complex and the removal efficiency is low. Heterotrophic nitrification/aerobic denitrification can turn ammonia into nitro-state and nitroso-state nitrogen by nitrification under aerobic conditions, and then revert to the gaseous nitrogen. So N2O or N2 can escape from the water directly into atmosphere. It provides the possibility for chance of nitrification and denitrification in a reactor under the same conditions. And the denitrification rate is faster in heterotrophic nitrification/aerobic denitrification heterotrophic. But Nitrification aerobic heterotrophic denitrifying bacteria is very immature, especially for high concentrations of ammonia nitrogen wastewater treatment. With the high osmotic pressure, high concentrations of ammonia nitrogen wastewater goes against microbial growth of microbe. Because of low rate of traditional microbial denitrification, traditional microbial can’t directly reduce high concentration of ammonia nitrogen wastewater. It is possible that high efficiency new biological denitrification bacteria is discovered for reducing the density of the high concentrations of ammonia nitrogen wastewater. And the solute osmotic pressure compensation offers a solution to train of thought. Therefore, we can try to use heterotrophic nitrification/solute aerobic denitrifying bacteria to reduce high concentrations of ammonia nitrogen wastewater with osmotic pressure compensation. Heterotrophic nitrification and aerobic denitrification bacteria with ability of both heterotrophic nitrification and aerobic denitrification, the discovery of this kind bacteria makes the aerobic condition for nitrification and denitrification at the same time possible. While the research of the heterotrophic nitrification and aerobic denitrification bacteria is not very mature so far, especially for high concentrations of ammonia nitrogen wastewater treatment.In order to obtain strains with high heterotrophic nitrification and aerobic denitrification efficiency,10 strains were isolated from the activated sludge. The ability of nitrification and denitrification were tested by the following standards:the aerogenesis of cells, the cell extration of liquid ammonia nitrogen and the deoxidation ability of nitrate. Three strains named D1, H2 and H3, which have high ability of heterotrophic nitrification and aerobic denitrification, were selected from the 10 strains and were tested the ability of heterotrophic nitrification and aerobic denitrification. There are also preliminary studies about the efficiency of reducing high concentration ammonia nitrogen in waste water using these three strains.The strains named D1, H2 and H3 are all with high heterotrophic nitrification and aerobic denitrification efficiency according to the ability test, and the heterotrophic nitrification and aerobic denitrification efficiency is 14%,21%,52% in 96 hours. In the aerobic condition, the compound strains (D1、H1 and H2) reduce the ammonia and nitrogen of high concentration ammonia nitrogen waste water, and the almost steady nitrogen removal efficiency is 42%.