Biological Removal Of Iron Manganese And Ammonia Nitrogen From Groundwater

Groundwater is an important fresh water resource for mankind, but it can not be widely used because of the presence of iron and manganese ions in the groundwater. Due to the emergence of biological removal technology, the problem is well resolved as the biological method is widely applied in many water plants. With the increasing environmental pollution in recent years, the pollutant of ammonia has been frequently found in groundwater and there seems to be a tendency of increasing in the future. In order to remove the iron, manganese and ammonia in groundwater at the same time, the study of removing iron and manganese and ammonia through the biological filter is then conducted in accordance with the potential risk.The base of experiments is at a groundwater plant in Harbin. The raw water of the plant is deep groundwater with high concentration of iron, manganese and ammonia nitrogen, and it is used as experimental water. Sometimes, the concentration values of iron, manganese and ammonia will be adjusted to meet the experimental needs. Firstly, start-up period is researched through dual-media filtration system which is constituted with anthracite and sand. And from this experiment, we find out the start-up periods for each pollutant in the biological purification filter layer. The start-up periods as follows: iron is about 10d, ammonia is about 30d, and manganese is about 50d. When the Biological purification filter layer turns to be mature, it is found that the removal space of iron, manganese and ammonia respectively are: the top part of filter columns is for iron's removal, the upper part of filter columns I for ammonia's removal, and the lower part of column filter is for manganese's removal; and the removal of ammonia nitrogen is mainly through nitrification in biological filter layer. Commonly, nitrification of 1mg / L ammonia consumes 4.57mg / L dissolved oxygen, which makes dissolved oxygen as the key factor to the success of purification process. Secondly, the limit of ammonia nitrogen removal has been studied. When ammonia chloride solution is added into the experimental water, results showed that under the condition of water with high concentration of ferrous ions, the maximum removal capacity of ammonia nitrogen is 1.59mg / L; when the water is with low concentrations of ferrous ions, the maximum removal capacity of ammonia nitrogen is 2.39mg / L. Finally, in order to process the water high concentration of ammonia accompany with iron and manganese, the dissolved oxygen in biological purification filter layer should be added to meet the demanding oxygen. So the middle aeration craft and the bottom aeration craft are supposed to solve the problem. Study results show that the: Backwash has some impact on the middle aeration craft, microorganisms in the ceramic layer will be washed away by backwash water; As to the bottom aeration craft, the iron concentration value of will be after backwashing, but it just lasts for a short time, then it will quickly return to the normal steady state. When it stays at the steady state, it is apparent that the removal of iron and ammonia nitrogen will maintain at a certain level. See from the removal of manganese, it is known that ceramic filter media is not suitable for the growth of manganese-oxidizing bacteria. This study not only enriches the theory of biological removal of iron and manganese, but also provides supporting ideas for processing groundwater which contains iron, manganese and ammonia.