[Limited time Q&A event No. 3] 009 (Ended) (3 Haiyou winners +30 wealth)

Nitrogen wastewater treatment method: The ammonia nitrogen wastewater is first filtered through a membrane filter, and the dilute ammonia water is filtered out and enters the isobaric recovery process to prepare concentrated ammonia water, which is carbonized to produce ammonium bicarbonate. The retentate is first hydrolyzed to extract kannakine, and the ammonia-nitrogen-containing organic wastewater generated is recycled to prepare coal-water slurry. ； The coal-water slurry with a concentration of 60% is carried out with the air-separated pure oxygen for gasification and cracking reaction under the conditions of 1350-1450℃, 1.3MPa high temperature and high pressure to generate CO, CO↓[2], H↓[2], N↓[2] and water gas with trace amounts of hydrogen sulfide. ； After the transformation process, CO reacts with water vapor to generate CO↓[2] and H↓[2] ； Then go through the desulfurization process to remove trace amounts of hydrogen sulfide through wet desulfurization. ； Part of the gas enters the carbonization process to remove CO↓[2] and generate ammonium bicarbonate at the same time. The other part of the gas enters the PSA hydrogen extraction process to prepare high-purity hydrogen, which is used as a finished product or used to prepare finished product liquid ammonia. In this way, waste is turned into treasure and operating costs are low.

Zeolite biochemical combined ammonia nitrogen removal technology is a new biological ammonia nitrogen removal technology. At present, there are few reports in this regard in China. There are also few research applications in this area abroad, and there is no specific research on the influencing factors of the biochemical deamination of zeolite nitrogen. However, preliminary research results show that zeolite biochemical technology has a good ability to buffer the impact load of ammonia nitrogen incoming water. ； As a carrier of spherical biofilm, zeolite can promote the transmission of ion ammonium and improve the denitrification effect. ； During operation, zeolite can be continuously biologically regenerated and recycled for a long time. Compared with simple zeolite ion exchange to remove ammonia nitrogen, the dosage of chemical regenerant can be reduced and the treatment cost can be reduced. ； Adding zeolite to the activated sludge system can improve the denitrification effect of the original nitrification and denitrification system, reduce the turbidity of the effluent, and reduce the concentration of suspended particles in the effluent. All these show that strengthening research in this area will have broad prospects.

When the ammonia nitrogen value in external sewage is less than 50 ppm, it can meet the discharge standard by directly discharging it into the sewage treatment plant for treatment.； If the ammonia nitrogen value of the discharged sewage is large, the sewage treatment plant cannot receive and process it. This type of sewage needs to be treated separately to remove ammonia nitrogen. After reaching the target, it will be discharged into the sewage treatment plant. ； Ammonia nitrogen in sewage can be removed by sewage stripping.

If the ammonia nitrogen in the sewage exceeds the standard, the ammonia is usually stripped out by steam stripping. Then, depending on the ammonia nitrogen content, it is decided whether to recover the liquid ammonia or burn it in the sulfur production unit.； The ammonia nitrogen content in the treated sewage can meet the requirements for further treatment in the sewage treatment plant ； This treatment method is more expensive.

At present, conventional technologies such as physical and chemical methods for treating ammonia nitrogen wastewater cannot achieve economical and effective treatment purposes at all, and there are problems such as poor treatment effects and high operating costs. Among biological treatment methods, A/O method, A2/O method, SBR sequential batch processing method and other process technologies that have certain effects on denitrification are generally used. The ammonia nitrogen content of generally treated wastewater cannot exceed 300 mg/L. At the same time, in order to achieve the purpose of denitrification, corresponding carbon sources must be supplemented to cooperate with the removal of ammonia nitrogen, which greatly increases operating costs, which is simply unbearable by ordinary enterprises. High-concentration ammonia nitrogen wastewater comes from many sources and has large emissions. It is urgent to adopt cost-effective and effective technologies to achieve treatment requirements. In recent years, with the development of bioengineering technology, especially the rapid progress of directional separation and cultivation of characteristic microbial engineering technology, the traditional denitrification theory has been challenged and broken in actual high ammonia nitrogen wastewater treatment projects. There has been a lot of progress in biological denitrification theory, and the new denitrification theory has been well verified in practice, such as: ①Nitrite nitrification/denitrification process. This process can save 25% of the nitrification aeration volume, 40% of the denitrification carbon source, and 50% of the denitrification reactor volume. ②Simultaneous nitrification/denitrification process (SND). In a reactor where aerobic and anoxic environments coexist, many new nitrogen biochemical bacteria have been identified, and nitrification/denitrification proceeds simultaneously under the action of bacterial micelle, thus achieving efficient denitrification under low carbon source conditions. ③Aerobic denitrification Under aerobic conditions, certain aerobic denitrifying bacteria can form gaseous products such as nitrogen oxide and nitrous oxide through the biological action of ammonia nitrogen. ④Anaerobic ammonium oxidation Some microorganisms can oxidize ammonia to nitrogen using nitrate, carbon dioxide and oxygen as oxidants. This post was last edited by hutom123 on 2009-4-29 09:28 ]

With the rapid development and growth of chemical fertilizer, petrochemical and other industries, the resulting high ammonia nitrogen wastewater has become one of the constraints on industry development. Therefore, cost-effective control of high-concentration ammonia nitrogen wastewater pollution has become an important research topic for current environmental protection workers, and has received great attention from industry insiders. At present, conventional technologies such as physical and chemical methods for treating ammonia nitrogen wastewater cannot achieve economical and effective treatment purposes at all, and there are problems such as poor treatment effects and high operating costs. Among biological treatment methods, A/O method, A2/O method, SBR sequential batch processing method and other process technologies that have certain effects on denitrification are generally used. The ammonia nitrogen content of generally treated wastewater cannot exceed 300 mg/L. At the same time, in order to achieve the purpose of denitrification, corresponding carbon sources must be supplemented to cooperate with the removal of ammonia nitrogen, which greatly increases operating costs, which is simply unbearable by ordinary enterprises. High-concentration ammonia nitrogen wastewater comes from many sources and has large emissions. It is urgent to adopt cost-effective and effective technologies to achieve treatment requirements. In recent years, with the development of bioengineering technology, especially the rapid progress of directional separation and cultivation of characteristic microbial engineering technology, the traditional denitrification theory has been challenged and broken in actual high ammonia nitrogen wastewater treatment projects. There has been a lot of progress in biological denitrification theory, and the new denitrification theory has been well verified in practice, such as: ①Nitrite nitrification/denitrification process. This process can save 25% of the nitrification aeration volume, 40% of the denitrification carbon source, and 50% of the denitrification reactor volume. ②Simultaneous nitrification/denitrification process (SND). In a reactor where aerobic and anoxic environments coexist, many new nitrogen biochemical bacteria have been identified, and nitrification/denitrification proceeds simultaneously under the action of bacterial micelle, thus achieving efficient denitrification under low carbon source conditions. ③Aerobic denitrification Under aerobic conditions, certain aerobic denitrifying bacteria can form gaseous products such as nitrogen oxide and nitrous oxide through the biological action of ammonia nitrogen. ④Anaerobic ammonium oxidation Some microorganisms can oxidize ammonia to nitrogen using nitrate, carbon dioxide and oxygen as oxidants. In short, there is a biological basis for greatly improving the efficiency of biological denitrification, and the increase in efficiency does not mean an increase in costs. Under this premise, the I-BAF process technology for treating high ammonia nitrogen wastewater came into being. This technology has unique technical and economic advantages in treating high ammonia nitrogen wastewater.: (1) I-BAF technology breaks and surpasses the theoretical basis of conventional nitrification/denitrification biological treatment of ammonia nitrogen wastewater. Due to the use of a special bacterial family (nitrogenophage bacteria) separated and cultured by special bioengineering technology, and a carrier that meets the biological environment needs of nitrogen-devouring bacteria to treat high ammonia nitrogen wastewater, biological reaction processes such as nitrification/denitrification, nitrite nitrification/denitrification processes, simultaneous nitrification/denitrification, aerobic denitrification, and anaerobic ammonium oxidation coexist in the I-BAF pool, and the most efficient denitrification efficiency can be achieved during the period. (2) Small equipment investment, low operating costs, and simple operation and management. Because it can remove high ammonia nitrogen more efficiently, and at the same time, there are very few supplementary carbon sources during the treatment of low organic matter and high ammonia nitrogen characteristic wastewater from fertilizer production enterprises. The amount of sludge produced by this treatment process is very small, and there is no need to increase high investment and expenses in sludge disposal. In the long-term water treatment equipment During construction and operation, there is no need to add microorganisms and carriers once they are put in. The immobilized microbial technology has strong resistance to fluctuations in incoming water, is easy to operate on site, and is easier to realize automatic control. Therefore, the I-BAF process technology has shown strong technical and economic advantages in treating high ammonia nitrogen wastewater. (3) I-BAF process technology can implement modular application and management. According to different treatment requirements, treatment units can be added or reduced, and the indicators of the treated water can be changed. When adding corresponding treatment modules, the effluent can be treated more deeply to meet the reuse indicator requirements, and can be used for production processes, circulating cooling water, green space or flushing, etc., saving a large amount of supplementary water, saving a large amount of sewage charges for enterprises, and saving a large amount of water costs. Removal of Ammonia Nitrogen from Wastewater Nitrogen in wastewater often exists in the form of nitrogenous organic matter, ammonia, nitrate and nitrite. Biological treatment converts most organic nitrogen into ammonia, which can then be further converted into nitrates. Currently, four nitrogen removal processes are used: biological nitrification and denitrification, zeolite selective exchange adsorption, air stripping and breakpoint chlorination. 　 1. Biological nitrification and denitrification (biological nitrogen aging method) Water Network Blog (1) Biological nitrification Water Network Blog Under aerobic conditions, the process of oxidizing ammonia nitrogen into nitrite nitrogen and nitrate nitrogen through the action of nitrite bacteria and nitrate bacteria is called biological nitrification. 1) During the nitrification process, 4.57g of oxygen is required when 1g of ammonia nitrogen is converted into nitrate nitrogen. ； (2) H+ is released during the nitrification process, which will consume the alkalinity in the wastewater. For every 1g of ammonia nitrogen oxidized, 7.1g of alkalinity (calculated as CaCO3) will be consumed. The main factors affecting the nitrification process are: (1) pH value When the pH value is 8.0 to 8.4 (20°C), nitrification is the fastest. Since the pH will drop during the nitrification process, when the alkalinity of the wastewater is insufficient, lime needs to be added to maintain the pH value above 7.5. ； (2) When the temperature is high, the nitrification rate is fast. The optimal water temperature for nitrite bacteria is 35°C. Its activity decreases sharply below 15°C, so the water temperature should not be lower than 15°C. ； (3) The proliferation rate of nitrifying bacteria in sludge residence time is very small, and its maximum specific growth rate is =0.3~0.5d-1 (temperature 20°C, pH 8.0~8.4). In order to maintain a certain amount of nitrifying bacteria in the pool, the sludge residence time must be greater than the minimum generation time of nitrifying bacteria. In actual operation, it should generally be >2, or >2 ； (4) Dissolved oxygen Oxygen is the electron acceptor in biological nitrification. If its concentration is too low, it will be detrimental to the nitrification reaction. Generally, when nitrification is carried out in an activated sludge aeration tank, the dissolved oxygen should be maintained above 2 to 3 mg/L. ； (5) BOD-loading nitrifying bacteria are a type of autotrophic bacteria, while BOD-oxidizing bacteria are heterotrophic bacteria. If the BOD5 load is too high, heterotrophic bacteria with a higher growth rate will multiply rapidly, so that white-trophic nitrifying bacteria will not have an advantage, resulting in a reduction in the nitrification rate. Therefore, in order to fully carry out nitrification, the BOD5 load should be maintained below 0.3kg(BOD5)/kg(SS).d. (2) Biological denitrification Under anoxic conditions, due to the action of facultative denitrifying bacteria (denitrifying bacteria), the process of reducing NO2--N and NO3--N to N2 is called denitrification. The electron donors (hydrogen donors) in the denitrification process are various organic substrates (carbon sources). Taking methanol as the carbon source as an example, the reaction formula is:: NO3-+2CH3OH→6NO2-+2CO2+4H2O NO2-+3CH3OH→3N2+3CO2+3H2O+60H- From the above, it can be seen that during the biological denitrification process, not only NO3--N and NO2--N can be reduced, but also organic matter can be oxidized and decomposed. 　　Main factors affecting denitrification: (1) Temperature The impact of temperature on denitrification is greater than that on other wastewater biological treatment processes. Generally, it is appropriate to maintain 20 to 40°C. In winter when the temperature is too low, measures such as increasing the sludge residence time and reducing the load can be taken to maintain good denitrification effects. ； (2) pH value The pH value of the denitrification process is controlled at 7.0~8.0 ； (3) Dissolved oxygen oxygen has an inhibitory effect on denitrification and denitrification. Generally, dissolved oxygen in the denitrification reactor should be controlled below 0.5mg/L (activated sludge method) or below 1mg/L (biofilm method) ； (4) Organic carbon source When the wastewater contains enough organic carbon source and BOD5/TN>(3~5), no external carbon source is needed. When the carbon and nitrogen ratio contained in the wastewater is lower than this ratio, additional organic carbon needs to be added. Methanol is often used to add organic carbon. Considering the additional consumption of dissolved oxygen by methanol, the dosage of methanol is generally 3 times that of NO3--N. In addition, microbial death can also be used ； The part of organic carbon released after autolysis is the "internal carbon source", but this requires a long sludge residence time or a low loading rate, which puts the microorganisms in the stationary phase or decay phase of the growth curve, so the pool volume increases accordingly. 2. Zeolite Selective Exchange Adsorption Zeolite is an aluminosilicate, and its chemical composition can be expressed as (M2+, 2M+) O.Al2O3.mSiO2·nH2O (m=2~10, n=0~9), where M2+ represents Ca2+, Sr2+ and other divalent cations, M+ represents Na+, K+ and other monovalent cations, it is a weakly acidic cation exchanger. In the three-dimensional structure of zeolite, it has regular pore structure and holes, which gives it excellent properties such as screening effect, exchange adsorption selectivity, thermal stability and shape stability. There are many types of natural zeolites, the main one used to remove ammonia nitrogen is clinoptilolite. 　　The exchange selectivity order of clinoptilolite for certain cations is:: K+, NH4+>Na+>Ba2+>Ca2+>Mg2+. Utilizing the strong selectivity of clinoptilolite for NH4+, an exchange adsorption process can be used to remove ammonia nitrogen from water. The exchange-adsorbed saturated whisk stone can be reused after regeneration. The pH value of the solution has a great influence on the ammonia removal by zeolite. When the pH is too high, NH4+ is converted to NH3, and the exchange adsorption effect is weakened. ； When the pH is too low, the competitive adsorption of H+ is enhanced, which is not conducive to the removal of NH4+. Usually, the pH value of incoming water is between 6 and 8. When treating urban water with ammonia nitrogen of 10 to 20 mg/L, the effluent concentration can reach below 1 mg/L. The water flow volume during penetration is about 100 to 150 bed capacity. The working exchange capacity of zeolite is about 0.4×10-3n-1mol/g. Zeolites that have reached saturation by adsorbing ammonium can be regenerated with 5g/L lime milk or saturated lime water. The dosage of regeneration liquid is about 3 to 5% of the treated water volume. Research shows that adding 0.1 mol of NaCl to the lime regeneration solution can improve the regeneration efficiency. In view of the scaling problem of lime regeneration, 2% sodium chloride solution is also used as the regeneration liquid. At this time, the amount of regeneration liquid is larger. The high-concentration ammonia waste liquid discharged during regeneration must be treated. The treatment methods are as follows:: (1) Air blow off the blown NH3 or exhaust it, or absorb it from H2S04 and use it as fertilizer ； (2) The steam stripping condensate is 1% ammonia solution, which can be used as fertilizer ； (3) Electrolytic oxidation (electrochlorination) oxidatively decomposes ammonia into N2. 3. Air stripping Under alkaline conditions (pH>10.5), ammonia nitrogen in wastewater mainly exists in the form of NH3. By allowing the wastewater to fully contact the air, the volatile NH3 in the water will transfer from the liquid phase to the gas phase, thereby removing ammonia nitrogen from the water. The stripping tower is filled with wood or plastic lath packing, the air flow enters from the lower part of the tower, and the wastewater falls from the top of the tower to the water collection tank at the bottom of the tower. The main factors affecting the ammonia stripping effect are:: (1) pH value Generally increase the pH value to 10.8~11.5 ； (2) When the water temperature decreases, the solubility of ammonia increases and the stripping efficiency decreases. For example, the ammonia removal rate is 90-95% at 20°C, but drops to about 75% at 10°C, which makes it difficult to operate the stripping tower in winter. ； (3) Hydraulic load Hydraulic load (m3/m2.h) is too large, which will destroy the water flow state required for efficient stripping and form a water curtain ； If the hydraulic load is too small, the packing may not be properly moistened, resulting in poor operation and a dry tower. The general hydraulic load is 2.5~5m3/m2. h ； (4) For a certain tower height, the air-water ratio can increase the ammonia removal rate by increasing the air flow rate. ； But as the air flow increases, the pressure drop also increases, so the air flow has a limit. Generally, the air/water ratio can be 2500~5000 (m3/m2) ； (5) Packing configuration and height Since repeated water splashing and formation of water droplets are the key to ammonia stripping, the shape, size, spacing, and arrangement of the fillers all have an impact on the stripping effect. Generally, the filler spacing is 40~50mm and the filler height is 6~7.5m. If the packing spacing is increased, a larger packing height is required ； (6) Scale control The scale (CaCO3) of the packing especially reduces the treatment efficiency of the stripping tower. Measures to control scaling include: Wash the scale layer with high pressure water ； Add antiscalants to the incoming water: Use air with low or low CO2 content to blow off (such as exhaust gas absorption and ammonia removal recycling) ； Use plastic fillers that are not prone to scaling to replace wood, etc. The air blowing method can remove ammonia with a removal rate of 60-95%. The process is simple, the treatment effect is stable, the infrastructure and operating costs are low, and it can treat high-concentration ammonia wastewater. However, when the temperature is low, the stripping efficiency is low, the scaling of the filling section often seriously interferes with the operation, and the ammonia blown out causes secondary pollution to the environment. 4. Breakpoint chlorination. The method of adding excess chlorine or sodium hypochlorite (exceeding the "breakpoint", see Chapter 14) to completely oxidize ammonia in wastewater to N2 is called breakpoint chlorination. The reaction can be expressed as: NH4 + + 1.5HOCl → 0.5N2 + 1.5H2O + 2.5H + + 1.5Cl- It can be seen from the reaction formula that the theoretical chlorine (C12) demand to reach the breaking point is 7.6kg/kg (NH3-N), while the actual chlorine demand is 8 to 10kg/kg (NH3-N). If the reaction is carried out at pH=6-7, the dosage can be minimized. The contact time is generally 0.5~2h. Strictly controlling the pH value and the amount of chlorine added can reduce the generation of harmful chloramines (such as NCl3) and chlorinated organic matter during the reaction. The breakpoint chlorination method has a removal rate of ammonia nitrogen of 90 to 100%. The treatment effect is stable, not affected by water temperature, and the infrastructure cost is not high. But its running costs are high ； Residual chlorine and chlorinated organic matter must be reprocessed. 　　Among the four denitrification processes currently used, the physical and chemical method has certain limitations in its practical application due to problems such as high operating costs and secondary pollution to the environment. The biological denitrification method can effectively and thoroughly remove nitrogen and is relatively economical, so it has been widely used.

The concentration discharged to the outside should not have recoverable value. The main purpose is to ensure that the ammonia nitrogen reaches the standard. Just add some oxidants, such as sodium hypochlorite.

If the concentration of ammonia nitrogen is relatively low, you can consider the ammonia blowing method, adjust the pH to about 10, keep the temperature at 30 degrees (higher temperatures are more ideal), and use aeration to blow off the ammonia nitrogen in the effluent. The ammonia nitrogen in the effluent can fully reach the standard, but the blowout gas should be recovered by acid to avoid polluting the atmosphere. If the ammonia nitrogen concentration is relatively high, normal anaerobic and aerobic processes cannot remove excessive ammonia nitrogen, and can only rely on physical and chemical methods (such as alkali stripping method, breakpoint chlorination method, chemical precipitation method, zeolite adsorption method, etc.). Although the process is cumbersome, the effect is good.

It uses a new bioactive filter material filter composed of oil inert and active filter materials (composed of polar and non-polar filter materials) for filtration. The removal rate of ammonia nitrogen is greater than 90%, which meets the requirements* * Standard requirements.

Prevention and control methods: 1. Add new water in time to dilute the ammonia nitrogen concentration in the original pool to prevent the poisoning from deepening. 2. Sprinkle salt to prevent the intrusion of ammonia nitrogen and nitrate nitrogen. . 3. Sprinkle zeolite powder and medical stone powder to absorb some harmful gases and toxic substances at the bottom of the pool. 4. After the poisoning is relieved, disinfectant should be added to the water body to sterilize it to prevent bacterial infection.