How to control total nitrogen exceeding the standard in wastewater treatment

1. Why should we control the discharge of total nitrogen? Excessive discharge of nitrogen in water will cause eutrophication of the water body, causing algae to multiply and bloom and red tide. When the total nitrogen content in the water is greater than 0.3mg/L, it will reach the point of eutrophication standard; in addition, nitrate itself is harmless to humans, but it will be reduced to nitrite in the body. On the one hand, nitrite will react with hemoglobin to form methemoglobin, which will affect the oxygen transmission capacity, especially for infants, which will easily lead to high iron Hemoglobinosis (blue baby disease); on the other hand, if nitrite is too high, it will form nitrosamines with protein, which is a strong carcinogen and is extremely harmful to health. 2. What is total nitrogen Total nitrogen is the general term for various forms of inorganic nitrogen and organic nitrogen in water. Total nitrogen (TN) = nitrate nitrogen + nitrite nitrogen + ammonia nitrogen (NH3-N) + organic nitrogen 3. How to remove total nitrogen Biological and chemical methods can be used for the removal of total nitrogen: 1. Biological nitrogen compounds in biological action The conversion to nitrogen can be realized under the following conditions: in this process, the number of pools is large, which makes the biochemical structure more complicated, especially the dissolved oxygen content in anaerobic pools is difficult to control, and the efficiency of denitrification is inhibited. On the one hand, denitrifying bacteria are rich The collection is slow, and it is easy to breed miscellaneous bacteria to compete for the living environment. On the other hand, the huge pool structure prevents the nitrogen gas from being discharged in time, which increases the proportion of invalid space. The number of denitrifying bacteria is always maintained at a total The low level makes it difficult to increase the denitrification load. The denitrification load of denitrifying bacteria cultivated in traditional biochemistry is usually less than 0.2kgN/m3d. For industrial wastewater, its high salinity and toxicity will make a large number of denitrifying bacteria death, thereby further reducing the denitrification load in this process, and the denitrification efficiency is reduced again. 2. The chemical method converts nitrogen compounds directly from organic nitrogen and ammonia nitrogen to nitrogen through oxidation. There are many defects in chemical denitrification. First, the oxidation cost is high; second, most chemical substances are only suitable for the strict operating conditions of the laboratory when used and reacted, so that the risk is within the controllable range, while in the actual wastewater treatment , the amount of water is large, the environment is poor, and the professionalism of the workers is not strong, so that there is a great potential safety hazard in the reaction process; in addition, the effect is often relatively poor due to inability to react. To sum up, the biological method has low cost and stable effect, but the process is complicated, the operation is difficult, and it occupies a large area, and the running time is long; the chemical method saves the intermediate conversion step, is faster and more direct, but the cost is higher. The breakpoint chlorine addition method is difficult to control and the effect is unstable. Both methods have their own advantages and disadvantages, and both need to be improved. With the strengthening of environmental protection, the sewage discharge indicators of all walks of life are becoming more and more stringent. The traditional two nitrogen removal methods no longer have the technical performance to meet the standards. Suzhou Zhanqing Environmental Protection Technology Co., Ltd. has conducted a three-year detailed investigation on the status quo of industrial wastewater treatment , developed the denitrification biological filter HDN technology, which solved the limitations of conventional biochemical methods, and at the same time greatly reduced operating costs, making the total nitrogen standardization process fast and convenient. 4. Total nitrogen standardization technology Through in-depth research on each link of denitrification, HDN technology has achieved the breakthrough of each defect one by one: 1) Bio-enrichment: In order to greatly increase the number of microorganisms per unit volume, in the filler The modified natural basalt is used in the link to improve the hydrophilicity of its surface and make it have a richer microscopic pore structure, making it easier for microorganisms to attach. 2) Bacteria domestication: In order to enhance the tolerance of denitrifying bacteria, the Dutch denitrifying bacteria were specially introduced. After three years of domestication, they can not only adapt to the complexity of industrial wastewater water quality, but also reproduce quickly and have a long life, which greatly improves denitrification. The denitrification load of the module. 3) Nitrogen release: In order to discharge nitrogen in time, through the special optimized design of the internal flow state of the reactor, a smooth exhaust micropore is established to promote the rapid discharge of the generated insoluble nitrogen, thereby reducing the dead zone of the reactor and The dead space improves the reactor stability and nitrogen removal efficiency.