Current status of ammonia nitrogen wastewater treatment at home and abroad 10

Sun Jinyi. Nitrogen-containing wastewater treatment technology and application. Beijing:

Chemical Industry Press, 2003 Zheng Ping, Xu Xiangyang, Hu Baolan. Novel biological nitrogen removal theory and technology. Beijing:

Science Press, 2004, Ye Jianfeng. New technology for biological denitrification treatment of wastewater. Beijing:

Chemical Industry Press, 2006, read it slowly.

Biological mechanism - biological nitrification and denitrification mechanism.

In the process of biological denitrification treatment of sewage, ammonia nitrogen in sewage is oxidized to nitrite or nitrate under aerobic conditions through the action of aerobic nitrifying bacteria, and nitrite and nitrate are reduced to nitrogen under anoxic conditions by denitrifying bacteria (denitrifying bacteria) and escaping from sewage. Therefore, the biological denitrification of wastewater includes two stages: nitrification and denitrification.

A o system: a o denitrification and phosphorus removal system, that is, anoxic, aerobic denitrification and phosphorus removal system, is mainly developed by the United States, South Africa and other countries in the 70s with the removal of nitrogen pollutants in wastewater process, at the same time also has a certain effect on dephosphorization, a o system process is simple, convenient operation and management, and easy to use the original factory to rebuild, thereby improving the effluent quality.

Notes:

The water quality of domestic sewage is usually relatively stable, and general treatment methods include acidification, aerobic biological treatment, disinfection, etc. The industrial wastewater should be reasonably selected according to the specific water quality situation.

In particular, it should be pointed out that for the use of aerobic biological treatment process to treat wastewater, it is necessary to pay attention to the biodegradability of wastewater, usually requiring COD BOD5, if the requirements cannot be met, anaerobic biological hydrolysis acidification can be considered to improve the biodegradability of wastewater, or consider the use of physical or chemical methods of non-biological treatment.

The above content reference: People's Daily Online - Solve the problem of excessive ammonia nitrogen in the Liaohe River Basin for 6 years.

Ammonia nitrogen wastewater treatment method:1.Blow-off method:

Under alkaline conditions, it is a method to use the gas-liquid equilibrium relationship between the gas-phase concentration and the liquid-phase concentration of ammonia nitrogen to separate, and it is generally believed that the blow-out is related to temperature, pH, and gas-liquid ratio.

2.Zeolite deamination method: The cations in the zeolite are exchanged with NH4+ in the wastewater to achieve the purpose of denitrification.

The application of zeolite deamination method must consider the regeneration of zeolite, usually there are regeneration liquid method and incineration method. When the incineration method is adopted, the ammonia produced must be treated, and this method is suitable for the treatment of low-concentration ammonia nitrogen wastewater, and the content of ammonia nitrogen should be 10--20mg l.

3.Membrane separation technology: a method for ammonia nitrogen removal using the selective permeability of membranes.

This method is easy to operate, has a high rate of ammonia nitrogen, and has no secondary pollution. For example, the gas-water separation membrane removes ammonia nitrogen.

Ammonia nitrogen has a dissociation equilibrium in water, and with the increase of pH, the proportion of ammonia in NH3 form in water increases, and the gaseous and liquid states of NH3 reach equilibrium at a certain temperature and pressure. According to the principle of chemical equilibrium movement, i.e. Lychardri (principle.

Removal of ammonia nitrogen, 1Strengthens oxidant, can be turned into nitrate or nitrite, 2Alkali is added, and heating can remove ammonia, 3It can be removed with anaerobic aerobic biochemistry.

In recent years, the country's environmental protection efforts have increased, as an important industry of pollution discharge, ammonia nitrogen wastewater treatment method is particularly critical, adsorption method to treat ammonia nitrogen wastewater, can efficiently remove ammonia nitrogen in wastewater, ensure that the treated wastewater content is below 20 mg l, meet the requirements of enterprises, reduce the pressure of wastewater follow-up treatment.

Look at the amount of sewage, if the amount is not large, less than 50 tons per day, you can use the built-in MBR system integrated equipment, do not occupy an area, intelligent operation. **Cheap, a ton of water costs almost 1 yuan. If the amount of wastewater is large and the site is sufficient, the biochemical + membrane or DTRO membrane system is the most ideal Chuyi, environmental protection.

Various wastewater treatment processes and equipment.

Look at the site conditions.

If there is a biochemical tank, adjust the aerobic tank and add nitrifying agent (RECY-DAN-02), which can quickly start the nitrification system, increase the sludge concentration and activity, and control the dissolved oxygen at the same time. Biochemical methods are more economical and have low operating costs.

If there is no biochemical tank, an oxidant can be added, but this method is more expensive and has the advantage that no modification is required.

With the rapid development of the national economy, the scale of China's chemical manufacturing industry, metal smelting and processing industry, petroleum processing industry and textile industry has developed rapidly, and at the same time, the discharge of ammonia nitrogen wastewater is also increasing. Ammonia nitrogen is a common pollutant in water pollution, and the presence of ammonia nitrogen will consume a large amount of oxygen in the water, resulting in eutrophication of the water body, resulting in the proliferation of algae plants, and a large number of fish dying due to lack of oxygen, thus affecting the development of human settlements and aquatic industry. In addition, ammonia wastewater can corrode metal pipes and water-using equipment by accelerating microbial growth, resulting in bioscale that can clog channels and affect heat transfer efficiency.

Therefore, it is of great significance to effectively treat ammonia nitrogen wastewater.

The breakpoint chlorination method is to introduce chlorine or sodium hypochlorite into the wastewater containing ammonia nitrogen, when the amount of chloride is reached, the amount of chloride ions contained in the wastewater is the least, the concentration of ammonia is zero, and the free chlorine in the solution will increase if the chlorine gas continues to be introduced. This point is called the breakpoint, and the concentration of free chloride ions is also the lowest in wastewater. This method of eliminating ammonia nitrogen is called the breakpoint chlorination method.

The removal of ammonia nitrogen by epipoint chlorination is due to the chemical reaction between chlorine and ammonia to produce nitrogen and water, which is harmless to the environment.

At the breakpoint, the chlorine is reduced, the ammonia nitrogen is basically oxidized, and the free residual chlorine is produced if the chlorination is continued. The main influencing factors of this method are temperature, pH value, contact time, and the amount of ammonia nitrogen and chlorine. The reaction equation was NH+4+HCl, NH2Cl+H++, and Ma Jinbao et al. used the breakpoint chlorination method to remove ammonia nitrogen from a low-concentration ammonia nitrogen wastewater generated during the preparation of manganese tetroxide by ammonium salt catalytic oxidation.

The test results showed that when the amount of Naclo added was 1800 (the volume ratio of sodium hypochlorite solution to ammonia nitrogen wastewater) at pH=7, the reaction time was 10min, and the removal rate of ammonia nitrogen in wastewater reached more than 98%. The test results show that when the ratio of pH=,Cl2 to NH+4 is 30min, the concentration of ammonia nitrogen in the wastewater drops to less than 10mg L, which meets the national ammonia nitrogen wastewater discharge standard.

Huang Haiming et al. used the breakpoint chlorination method to treat the low-concentration ammonia nitrogen industrial wastewater generated in the process of rare earth smelting, and the test results showed that the removal rate of ammonia nitrogen in the waste liquid reached 98% when the ratio of Cl to NH+4 was 71 and the reaction time was 10 15min.

High in ammonia nitrogenWastewater treatment methodsAs follows:

1. Blow-off method.

The basic principle of blow-out fidver is the theory of gas-liquid equilibrium and mass transfer velocity. Adjust the pH of ammonia nitrogen wastewater to alkaline, at this time, ammonium ions.

It is converted into ammonia molecules, and then gas is introduced into the water, so that it is in full contact with the liquid, and the dissolved gas and volatility in the wastewater.

Ammonia molecules pass through the gas-liquid interface and are transferred to the gas phase, thereby achieving the purpose of removing ammonia nitrogen. Air or water vapor is commonly used.

As a carrier gas, the former is called air blow-off, and the latter is called steam blow-off.

2. Mega-defeat ion exchange method.

The ion exchange method is used to treat wastewater containing ammonia nitrogen, and the most common is zeolite.

As an exchange carrier, the ammonia nitrogen removal rate is improved. Based on historical practice data, it can be seen that each gram of zeolite can adsorb ammonia nitrogen, and for zeolite with a particle size of 30 to 60 mesh, its ammonia nitrogen removal efficiency can reach 78%. However, compared with other treatment technologies, the use of zeolite exchange removal process is more complicated, and the regenerated liquid is a high-concentration ammonia nitrogen wastewater that needs to be retreated, so it is more suitable for low-concentration ammonia nitrogen wastewater treatment.

Technical parameters for the treatment of ammonia nitrogen by blow-off method

1) The pH of the blow-off method is generally around 11;

2) Considering economic factors, it is more feasible to have a temperature around 30 40 and a high treatment rate;

3) The blow-off time is about 3 h;

4) The gas-liquid ratio is better when it is about 5 000 1, and the higher the blow-off temperature, the smaller the gas-liquid ratio;

5) The concentration of wastewater can be reduced to medium and low concentration after blowing;

6) The denitrification rate is basically maintained at more than 90%. Although most of the ammonia nitrogen can be removed by the blowing method, the ammonia nitrogen in the treated wastewater is still as high as more than 100 mg l, which cannot be directly discharged, and further treatment is required.

If the wastewater containing ammonia nitrogen element is directly discharged in nature, it will cause eutrophication of water, and finally cause black odor of water body, which not only increases the difficulty of water treatment, but also causes black odor of water bodyShould ammonia nitrogen wastewater in the chemical industry be treated better?

chemical industryAmmonia nitrogen wastewaterIt is mainly divided into ammonia nitrogen formed by ammonia water and ammonia nitrogen formed by inorganic ammonia, and its sewage is mainly used in the fields of pharmaceutical, food, fertilizer, coking and petrochemical.

For the treatment of such wastewater, physicochemical methods can be used: blowing method, zeolite deamination method, membrane separation technology, MAP precipitation method, chemical oxidation method, biological denitrification method: activated sludge method, strong oxidation aerobic biological treatment, short-range nitrification and denitrification, ultrasonic blowing treatment of ammonia nitrogen method, biochemical combined method.

The process flow of biological denitrification method is approximately:

A o—Two-stage activated sludge method—Delayed aeration (residence time is about 36 hours)—This song, strong oxidation, aerobic biological treatment—Short-range nitrification, denitrification—Ultrasonic blowing treatment, ammonia nitrogen method.

In the activated sludge method, it can effectively remove organic matter and ammonia nitrogen, and when the sewage concentration is less than 2g l, Sakura can choose to discharge less sludge or no sludge to reduce sludge treatment costs.

For other water treatment processes of ammonia nitrogen wastewater: "ammonia distillation (stripping) or blowing off + AO or blowing + chemical precipitation" has high investment and high operating costs.

At present, there are various methods for the treatment of high ammonia nitrogen wastewater, such as breakpoint chlorination, chemical precipitation, ion exchange, and biological deamination. So how to choose the treatment method of high ammonia nitrogen wastewater?

Chemical precipitation.

The basic principle of the chemical precipitation method is to add phosphide and magnesium to the high ammonia nitrogen wastewater to generate ammonium magnesium phosphate precipitation, so as to achieve the effect of removing ammonia nitrogen.

Biological law. Biological denitrification technology is widely used, but the concentration of ammonia nitrogen in high ammonia nitrogen wastewater will affect microbial activity, and the raw water needs to be diluted. In addition, the digestion process requires a large amount of dissolved oxygen, and the denitrification process requires a large carbon source.

The common biological removal process of high ammonia nitrogen wastewater is membrane bioreactor method and anaerobic ammonia oxidation method. HNF-MP high-efficiency nitrification reaction system, on the basis of traditional biological nitrification, the reactor structure is improved, the inlet pipeline is insulated, if the water temperature is lower than 18 degrees, the steam heat exchanger at the front end of the inlet water is controlled, and the temperature is maintained at 25-30. By optimizing strains, highly active strains that are resistant to salt and toxic impacts are obtained, and at the same time, the original multi-stage precipitation separation technology enriches and strengthens nitrifying bacteria to the greatest extent, and the denitrification efficiency is 3 times that of traditional technology.

Chemical oxidation.

The breakpoint chlorination method is a chemical denitrification process in which excessive chlorine or sodium chlorate is added to oxidize ammonia nitrogen in wastewater into nitrogen.

Blow-off method:A water treatment method that uses air collapse to oxidize with dissolved gases in water when passing through wastewater, so that the dissolved volatile substances in the water are transferred from the liquid phase to the gas phase, and further blown off and separated.

Physicochemical method, blow-off method.

Under alkaline conditions, the gas-liquid equilibrium relationship between the gas-liquid concentration and the liquid phase concentration of ammonia nitrogen is used to separate a delay method, and it is generally believed that blow-off is related to humidity, pH, and gas-liquid ratio.

The cations in the zeolite are exchanged with NH4+ in the wastewater to achieve the purpose of denitrification. The application of zeolite deamination method must consider the regeneration of zeolite, and there are usually regeneration liquid method and incineration method. In the case of incineration, the ammonia produced must be treated.

If a large amount of ammonia nitrogen wastewater is discharged into the water body, it will cause eutrophication of the water body, and it will also cause the black odor of the water body, which will then cause the difficulty and cost of water treatment to increase, and it will also have a toxic effect on organisms and human beings themselvesAmmoniaWhat are the common methods of nitrogen wastewater treatment?

For food, organic fertilizer, petrochemical, pharmaceutical, coking and other industries will produce ammonia nitrogen wastewater, due to the different components of wastewater produced by different industries, it is necessary to conduct experimental tests according to the user's sewage, and then formulate according to the composition of the sewageWater treatment schemes.

Physicochemical methods (blowing method, zeolite deamination method, membrane separation technology, MAP precipitation method, chemical oxidation method) and biological denitrification method.

Ammonia nitrogen wastewater treatment equipment process:

The industrial wastewater containing ammonia nitrogen uses large-particle light ceramsite filter material in the feedwater aeration biological filter to have a low filtration interception rate of the raw water under the uplift condition, and the filtered water quality generally does not exceed 5kpa.

Under appropriate circumstances, the requirements for the specific surface area of the filter material are reduced, and the filtration rate is greatly increased to 16 20m h, and the air-water ratio is 0.

Under the dual action of biochemical and filtration of biofilm on the surface of large-particle light ceramsite filter media, the pretreatment of ammonia nitrogen < in the effluent provides an efficient, energy-saving and land-saving treatment process for the treatment of micro-polluted source water.

Physicochemical methods are not limited by high ammonia concentrations in wastewater with high concentrations, but they cannot reduce ammonia concentrations to low enough (e.g., below 100 mg l).