Method and principle of total nitrogen removal

1. Composition of total nitrogen in wastewater Total nitrogen is mainly composed of ammonia nitrogen, organic nitrogen, nitrate nitrogen, nitrite nitrogen and nitrogen oxides, among which ammonia nitrogen mainly comes from inorganic substances such as ammonia water and ammonium chloride. Organic nitrogen mainly comes from nitrogen-containing groups in some organic compounds, such as organic amines. Nitrogen oxides, such as nitric oxide and nitrogen dioxide, are toxic gases, and generally rarely exist because of their unstable state. The properties of nitrate nitrogen are relatively stable and its content is relatively high. For example, in the process of explosive manufacturing in the national defense industry, a large number of related raw materials are used as oxidants in industries such as mechanochemistry. At the same time, many sewage also contains a lot of nitrate nitrogen which has undergone biochemical and nitrification in the early stage, because nitrate nitrogen is very stable and easily soluble in water. 2. Removal method of ammonia nitrogen At present, the technology of ammonia nitrogen-containing wastewater on the market is very mature, and it is generally removed by the following methods. One is the inflection point chlorine oxidation method, which converts ammonia nitrogen into nitrogen and releases it by adding secondary or bleaching powder for oxidation. At present, the main ammonia nitrogen remover on the market is bleaching powder. The reaction equation is as follows: 2nh2cl+hclo → N2 ↑+3h+3cl-+H2O. Secondly, ammonia nitrogen in wastewater is removed by microbial nitrification and denitrification. The principle is that nitrifying bacteria and denitrifying bacteria work together to transform ammonia nitrogen in water into nitrogen to achieve the purpose of nitrogen removal. Firstly, ammonia nitrogen was transformed into sub and sub by nitrifying bacteria and nitrosating bacteria, and then sub and sub were transformed into nitrogen by denitrification. The reaction scheme is as follows: 2NH3+3O2→HNO2+H2O+ energy (nitrosation) 2HNO2+O2→2HNO3+ energy (nitration) HNO3+CH3OH→N2+CO2+H2O+ energy (denitrification) 3. Removal methods of organic nitrogen Some wastewater contains organic nitrogen, which is mostly removed by microorganisms. In the transformation, it mainly includes three stages: ammoniation, nitrification and denitrification. In the process of ammoniation, organic nitrogen in water is transformed into ammonia nitrogen by microorganisms. In the process of nitrification, Ammonia nitrogen is first transformed into sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub-sub. At present, there are ion exchange method, membrane permeation method, adsorption method and biological denitrification method. Among them, ion exchange method, membrane permeation method and adsorption method are only the concentration and transfer of radical ions, and can not really remove total nitrogen. The concentrated root waste liquid needs further treatment. In biological denitrification, it mainly refers to the process that root ions are degraded by denitrifying bacteria and converted into nitrogen. The traditional biochemical method needs a large area, and because of the low microbial density, the microbial denitrification efficiency is very low, the effluent is unclear, there are suspended substances, and there is no tolerance to toxic substances. Suzhou Zhan Qing Environmental Protection Technology Co., Ltd. has newly designed an efficient denitrification biofilter. The high-efficiency denitrification biofilter with special structure is specially developed for the treatment of industrial wastewater, which adapts to the characteristics of high salinity, high toxicity, high nitrate nitrogen and large fluctuation of industrial wastewater. This technology has the following characteristics: high nitrogen removal efficiency-normal operation nitrogen removal load 2kgN/m? D, the occupied area of effluent total nitrogen is small-the treatment capacity 10t/h, the total nitrogen is reduced by 20mg/L, and the occupied area is only 3m2, which is convenient for operation and maintenance-fully automatic control, no need to change fillers, less backwashing water, low frequency and low sludge output-a small amount of microorganisms discharged from backwashing are returned to the biochemical tank for further decomposition, and the operating cost is low-the total amount is removed by 20%.