Magnetic Particles Induce Anammox Bacteria Enrichment And The Autotrophic Nitrogen Removal System Quickly Start

Nitrogen is one of the main elements of polluted water. Nitrogen removal treatment can effectively prevent water eutrophication. In the traditional process of nitrification and denitrification, the nitrification process needs aeration and the denitrification process that in low organic matter concentration wastewater should added the carbon source, which increase the energy consumption and treatment cost. The discovery of anaerobic ammonia oxidation reaction, which laid a foundation for efficient and low consumption of biological denitrification treatment. Anaerobic ammonium oxidizing bacteria?AAOB? take carbon dioxide as the carbon source and nitrite as electron acceptor, which greatly reduce the cost of aeration and carbon source in sewage treatment plant. However, the generation period of AAOB is long and the requirement for living environment is harsh, which hinder the promotion of anaerobic ammonium oxidation technology.This topic is aimed at the problem of slow start of Anammox process. Exploring the distribution of magnetic field in the solution of magnetic materials and preparing the improved magnetic particles. Using the magnetic field of the magnetic particles to induce the enrichment of AAOB, and to promote the coupling of ammonia oxidizing bacteria?AOB?and AAOB. The main results obtained are as follows:The magnetic field intensity distribution formed by the external magnetic field is not uniform.When the distance between the test point and the source of the magnetic field is increased, the intensity of the magnetic field is rapidly fading; The uniformity of the distribution of magnetic field in the reactor can be effectively improved by adding magnetic powder into the solution. The average magnetic field intensity of Fe₃O₄?11.68⁵4.97um?,Fe₃O₄?20nm?, and Fe Co Ni?178um? were increased with the increase of magnetic particle mass?20¹20g/L?.Under the condition of the same quality, the magnetic field intensity produced by the three kinds of magnetic particles decreased in the solution. The magnetic field intensity produced by Fe₃O₄?11.68⁵4.97um? is higher than that of Fe₃O₄?20nm?. The intensity of magnetic field produced by Fe₃O₄?11.68⁵4.97um? is smaller than that of themagnetic field produced by Fe Co Ni?178um?. But Fe Co Ni?178um? is easily oxidized in water and cause the decrease of the magnetic field strength. Therefore, the Fe₃O₄?11.68⁵4.97um? magnetic powder is suitable to be used as the source material of the magnetic field in the reactor. In the experiment, Fe₃O₄?11.68⁵4.97um?, cement and other materials were used to prepare magnetic particles?1²mm?.The prepared magnetic particles can further improve the magnetic field intensity in the reactor, and the magnetic particles have a higher specific surface area, which is favorable for the enrichment of microorganisms, and greatly reduces the loss of magnetic materials.Study the enrichment of AAOB with different magnetic field intensity induced by magnetic particles. In the six groups of different quality of magnetic particles placed in the modification, the pilot plant, the formation of magnetic field intensity in turn is: 0.00 mT,0.30 mT, 0.60 mT, 0.78 mT, 0.95 mT, 1.10 mT. After 60 days of anaerobic culture, the water quality was detected after 36 hours and the results showed that the total nitrogen removal efficiency was the best when the magnetic field intensity was 0.78 mT, and the removal rate was 0.304kg/m3·d.When the magnetic field intensity increased to 0.80 mT and 1.10 mT, the total nitrogen removal rate decreased to 0.26kg/m3·d.AAOB enrich regularity is studied by contrast test in different magnetic field intensity,inoculation sludge and influent ammonia concentration conditions. The study found that the total nitrogen removal rate of the anaerobic reactor was improved when the magnetic field strength was in the range of 0.30 mT⁰.78 mT after the operation was stable.When the reactor was inoculated with denitrification sludge and its magnetic field intensity was 0.78 mT, 0.95 mT, 1.10 mT, respectively, study the effect of ammonia nitrogen concentration of 20⁴5mg/L and 50⁷5mg/L on the concentration of AAOB, and it was found that the formation of nitrate nitrogen and the removal of ammonia nitrogen from the high ammonia nitrogen intake reactor was close to the theoretical value of the anaerobic ammonium oxidation reaction.In the experiment, the start-up regulation of the autotrophic nitrogen removal system was studied by using a sequencing batch reactor. Studies have found that using Anammox sludge mixed with denitrifying sludge as inoculation sludge can be more quick star-up autotrophicnitrogen removal system compared with pure inoculated denitrifying sludge, and the total nitrogen removal rate was better. The activity of AAOB was inhibited when the p H value was8.5⁸.9, which resulted in the accumulation of nitrite nitrogen in the reactor. The optimal dissolved oxygen concentration in the self nutrition denitrification reactor was 0.5⁰.9mg/L.Low dissolved oxygen concentration will inhibit the activity of nitrate salt oxidizing bacteria,makes the reactor nitrite deficiency and inhibition of Anammox reaction; High dissolved oxygen can inhibit the activity of anaerobic bacteria, which can also affect the Anammox reaction.Molecular biological experiments of sludge in different stages and under different culture conditions: 1)The similarity of inoculated nitrification sludge and denitrification sludge reached 55.3%, and the similarity decreased to 27.7% after two months of anaerobic operation; 2) Analysis of PCA showed that the similarity of microbial population with similar culture conditions was also higher; 3)Under anaerobic conditions, the microbial diversity of inoculated sludge decreased. The sample Shannon index of the inoculated nitrification sludge decreased from 2.91 to 1.69 and the Shannon index of the samples inoculated with the denitrification sludge decreased from 2.38 to 2.04; 4)The microbial diversity of the self nutrient nitrogen removal system was higher than that of the anaerobic ammonium oxidation system; 5)AAOB enrichment stage, the dominant bacteria in the reactor is mainly anaerobic and anaerobic bacteria. In the stage of self nutrition and nitrogen removal, the dominant bacteria in the reactor were mainly aerobic and anaerobic bacteria.