In addition to COD, another important indicator of water quality control is nitrogen content. Traditional sewage treatment is generally a process of nitrification, denitrification, and denitrification, which requires additional carbon sources and alkalis. Not only is the operating cost high, but it may also cause secondary pollution. Affect the denitrification treatment effect. With the continuous progress of science and technology, people gradually began to pay attention to the new biological denitrification technology. Due to its unique characteristics of high efficiency and low consumption, anammox technology came into being and was gradually developed and applied.
The mechanism of anammox reaction
According to the investigation and research of relevant scholars, anammox technology mainly refers to the use of nitrite nitrogen (NO2-N) as an electron acceptor and ammonia nitrogen (NH4+N) as an electron donor in an anaerobic environment, and then in the anaerobic environment. HCO3- and CO2 as carbon sources. A process in which ammonia nitrogen is oxidized to nitrogen gas (N2) using anammox bacteria. In this process, a certain amount of hydroxylamine (NH2OH) and hydrazine (N2H4) are bound to be generated, so the process should be continuously improved and perfected. The specific reaction formula is as follows:
According to the above reaction equation formula, we can draw the principle of anammox technology: a certain amount of HCO3- and CO2 will be consumed in the anammox reaction without adding additional carbon sources, which can not only effectively achieve It saves cost, and can effectively prevent two kinds of pollution generated in the reaction; almost no N2O is produced in the reaction process, which can effectively avoid the denitrification caused by traditional greenhouse gas emissions. The reaction process of producing alkali is zero, no need to add neutralizing reagent, and it is more environmentally friendly. In addition, the technology also has the advantages of less mud production, saving oxygen consumption, etc., and has the significance of sustainable development and utilization.
Anaerobic ammonia oxidation wastewater treatment process
2.1 Nitrosing anammox process
Anammox is one of the most commonly used ammonium oxidation processes in wastewater treatment. The wastewater treatment process is mainly divided into two stages, and the two stages are carried out in different containers. The first stage is nitrification, which converts ammonia nitrogen into nitrite ammonia sewage by 50%, and the second stage of anaerobic ammonium oxidation, which converts nitrate-nitrogen from the anaerobic ammonium oxidation reaction of residual element ammonia and nitrogen element in the sewage into production, So as to achieve the purpose of removing ammonia nitrogen. The nitrosation-anammox process has four advantages. The first is that nitrosamine is produced in the process of nitrification and anammox. This substance is an alkaline substance that produces a certain amount of bicarbonate with anaerobic water to achieve acid-base neutralization. It can help achieve water The acid-base balance and then nitrification of anammox wastewater treatment due to the reaction process in different vessels, and the reaction vessels in different environments. Functional bacteria provide a more suitable environment for their own growth, which is water can reduce the inhibitory effect of substances on anammox bacteria. The other is to use the nitrification anammox process for sewage treatment. Although it belongs to a combined process, the operation process is very simple and requires a wider range of pH values. Finally, the nitrification anammox process reduces these in sewage treatment. Due to the existence of these advantages, the nitrosation anammox process has become an indispensable technology in wastewater treatment.
2.2 Total auto-oxygen deamination process
In the whole process of wastewater treatment using oxygen and ammonia nitrogen, nitrification and anaerobic ammonia oxidation are mainly realized through the control of dissolved oxygen, and in the process of sewage treatment, autotrophic bacteria can respectively convert ammonia and nitrogen elements in water into Nitrogen. In the process of sewage treatment, since the whole process is carried out in a micro-aerobic environment, nitrogen is generated through the residual anaerobic oxidation reaction of nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen produced by the chemical reaction of nitrifying bacteria, and during the whole reaction In the process, since nitrite-oxidizing bacteria and anammox bacteria belong to the category of autotrophic bacteria, it is not necessary to continue to add exogenous organic matter in the process of fully autotrophic denitrification wastewater treatment, but it only needs to be in an inorganic autotrophic environment throughout the process. However, since the entire auto-oxygenated ammonia process is more susceptible to the interference of nitrate bacteria in sewage treatment, the operating conditions of the auto-oxygenated ammonia process must be strictly controlled to achieve a balance between oxygen and nitrite.
Application of anammox wastewater treatment
With the continuous in-depth research of anammox technology by relevant scientific researchers, a variety of practical wastewater treatment applications have been successfully realized, such as domestic sewage, coking wastewater, municipal sludge liquid, toilet water, landfill leachate, And the effective treatment of monosodium glutamate wastewater, and gradually promote the use of other wastewater in the field of treatment. But at present, for some high-ammonia industrial fields such as pharmaceuticals and aquaculture, the application of anammox technology in wastewater treatment is still relatively small, which is also the direction of future efforts. Several typical anammox wastewater treatments’ practical application effects are selected below for reference.
3.1 Sludge liquid wastewater treatment
In the process of using anaerobic ammonia to treat sludge and wastewater, the most typical ones mainly include sludge press filtrate and sludge digestion liquid. Usually, the temperature should be controlled at 30 to 37 degrees Celsius, and the pH should be controlled. Between 7.0 and 8.5, because only this pH value and temperature conditions are most conducive to the growth of anaerobic bacteria. Some foreign researchers have conducted repeated research on this treatment technology for a long time. In 2002, the world’s nitrosation-anammox combined reactor was finally formed, and the reactor was further applied to Dokhaven sewage treatment. in the factory. Since then, various European countries have carried out a lot of research and experiments on the treatment of sludge and wastewater using anammox technology. Because this technology has the characteristics of high water temperature, small water volume, low carbon-nitrogen, and high ammonia nitrogen, etc. In fact, this is also the initial treatment object of anammox technology. Therefore, most of the anammox projects in the world are processed by sludge liquid, which has quite a mature experience. However, due to the limitation of technical conditions, the influence of sulfide in the anammox process and the measures to reduce emissions still need to solve some technical problems in future research and practical development.
Landfill leachate is characterized by high ammonia content, high concentration of organic matter, changes in water quality, and easy to contain toxic substances such as heavy metals. It is a complex sewage composition. Ammonia nitrogen concentration is generally 2000mg/L, and the increased garbage collection time will become higher and higher. Some scholars have studied the leachate of the landfill and found the phenomenon of insufficient anaerobic ammonium infiltration, which makes the anaerobic ammonium oxidation technology possible in the treatment. From the research of landfill leachate by anammox technology in the treatment point of view, most of them use a short-range nitrification-anammox process, some new technologies have been tried, but because it contains a lot of toxic substances, it is very difficult Easy to make inhibition of anammox activity. For effective and stable operation performance, it is also necessary to effectively regulate and inhibit the leachate in the microbial flora, etc., and also need to research and optimize related technologies.
3.3 Urban domestic sewage treatment
With the rapid development of my country’s social economy and the continuous acceleration of urbanization, the production of urban industrial sewage and domestic sewage is also increasing. To effectively treat this sewage and better realize the sustainable development of the city, It is necessary to choose a sewage treatment technology with a very good treatment effect and to recycle the treated water again. This problem has become an urgent problem to be solved in our country. Since urban sewage contains a large amount of phosphate, organic carbon and ammonia nitrogen, and other substances, and such a water environment is just the best environment for the growth and reproduction of denitrification microorganisms, it should be fully utilized in the process of sewage treatment. Effective purification and recycling, so as to achieve self-sufficiency of energy in the sewage plant. However, when it is used specifically, if the water temperature is too low, especially in the winter environment, it will be difficult to use this technology to treat sewage. Although many foreign scholars in this field, such as Lotti, have made great breakthroughs in this issue, they have also made great progress in the phased research on the pilot test (4m3, 19℃±1℃). There is a certain hope to achieve energy self-sufficiency in sewage treatment plants, but in practical applications, it may be affected by various external factors, such as how to achieve overall amplification or how to effectively improve bacteria in a relatively low-temperature environment. A series of problems such as the activity of swarms are all problems that need to be solved in future research. Only when these problems are well solved can the effective treatment and recycling of urban sewage be effectively realized.
3.4 Livestock and poultry breeding sewage treatment
The sewage has the characteristics of complex composition, high COD concentration, large water quality fluctuation, and high organic nitrogen content. Using traditional denitrification technology to treat livestock and poultry wastewater not only consumes high energy, but also needs to add a carbon source, and the denitrification effect is not ideal. Modern anammox processes have the advantages of traditional processes and are expected to be an alternative technology for treating such wastewaters. At present, after using anaerobic technology to treat the wastewater generated in the process of livestock and poultry breeding, there are still problems in operation. It is necessary to further optimize the process and find out the countermeasures to eliminate the growth obstacles of anammox bacteria, so as to ensure the field of livestock and poultry wastewater treatment exerts its best efficiency.
All in all, with the rapid development of industrialization today, it has brought more and more pressure to the water environment. Only by continuously improving and innovating various sewage treatment technologies can we realize the recycling of water resources and realize the sustainable development of the city. develop.