Study On Biological Treatment Technology Of Combined Contaminated Groundwater Containing Manganese And Ammonia Nitrogen

In the migration process, groundwater is subject to being affected by human industrial and agricultural activities, resulting in the water pollution. Groundwater containing manganese is widely distributed in our country. In some regions, the pollution of groundwater containing manganese is usually accompanied by increase of the concentration of ammonia nitrogen, which leading to the composite manganese and ammonia nitrogen pollution. The removal of manganese in these polluted groundwater is affected by ammonia nitrogen which also needs to be removed efficiently, so the study of best removal techniques under the condition of combined pollutions is of great significance. And this thesis is mainly aimed at this point.Firstly, researches on domestication culture methods of autotrophic manganese removal bacteria and nitrifying bacteria and the efficiency of two strains in removing manganese and ammonia nitrogen were made. And then, the inoculation to filtration columns and the initial culture were studied, and the factors influencing the mature filter-layer were discussed. Finally, the biological treatment process of water with high manganese and high ammonia nitrogen compound pollution was preliminarily established.Initial strains of this study is obtained from samples at the end of the A2/O aerobic tank. And the autotrophic manganese removal bacteria and nitrifying bacteria with high efficiency were got through domestication culture in JFM medium and George Stephenson medium, respectively. Autotrophic manganese removal bacteria were got after six cycles of subculture, and manganese removal rate is 93.89%. Nitrifying bacteria were got after five cycles of subculture, and final ammonia nitrogen removal rate is 82.5%. Small scale tests on the efficiency of two strains in removing manganese and ammonia nitrogen were carried out Results showed that the nitrifying bacteria has no ability to remove manganese by itself, but its growth requires trace amount of manganese as growth factor; manganese oxidation bacteria do not play important roles in removing ammonia nitrogen, and they just absorb a little of ammonia nitrogen to improve its growth. The exists of ammonia nitrogen do not affect the efficiency of manganese removal by manganese oxidation bacteria; during the treatment process of manganese and ammonia nitrogen composite groundwater by bio-filter, manganese oxides generated by manganese oxidation bacteria do not influence the removal of ammonia nitrogen, i.e. manganese oxides play no roles in the process of ammonia-nitrogen removal.Filter column 1# and 2# was inoculated with manganese oxidation bacteria and then started training. Water into filter columns was artificial simulation groundwater. Filter column #1 started after 75 days, and filter column #2 completed starting process through about 65 days. After startup is completed, both the concentration of manganese and ammonia nitrogen can reach drinking-water standard, and mature filter column surfaces are covered with black biofilm layers. Filter column 3# and 4# was inoculated with nitrifying bacteria and then started training. It took 25 days to complete the startup process. After filtration, the concentration of ammonia nitrogen in the effluent is maintained at about 0.3 mg/L. Study indicated that nitrifying filter columns didn’t have the ability to remove manganese, and no black substance was generated in the filtration columns. Nitrifying bacteria only absorbed a small amount of manganese ions to meet their growth needs. Filtration rate has significant effect on the performance of biological filters. In order to make the manganese and ammonia nitrogen in effluent meet water standards, filtration rate of the manganese removal filter columns need to be less than 13 m/h, and nitrifying filters be under 12 m/h. The nitrifying filters have the highest performance under the weak alkaline condition and when pH=8, they work best. The maximum concentration of ammonia nitrogen that manganese removal bio-filters can bear is 3 mg/L and the one that nitrifying filters can bear is 13 mg/L. Studies about effects of the manganese concentration on the ammonia nitrogen removal by manganese removal bio-filters showed that maximum concentration of manganese that manganese removal columns can bear is 3.5 mg/L and as manganese concentration increased, the ammonia concentration of effluent is not affected, keeping effluent meet standards. The study on ammonia-nitrogen removal along change showed that the removal of manganese and ammonia nitrogen is synchronous. The ammonia nitrogen removal took place in the upper filter column and biological removal of manganese took place in the lower column.In the study on applications of "primarily biological nitrification+secondarily biological oxidation manganese removal" series, experiments were carried out at the filtration rate of 6 m/h and 12 m/h, respectively. Results demonstrated that in the case of high manganese and high ammonia nitrogen, filtration system could run stably and can ensure the ideal treatment of manganese and ammonia nitrogen to make effluent meet standards. On the contrary, addition of aeration devices at the middle and bottom of single-stage biological manganese removal filter columns did not achieve the same effect.