1.What is ammonia nitrogen?
Ammonia nitrogen refers to ammonia in the form of free ammonia (or non-ionic ammonia, NH3) or ionic ammonia (NH4+). Higher pH and higher proportion of free ammonia; On the contrary, the proportion of ammonium salt is high.
Ammonia nitrogen is a nutrient in water, which can lead to water eutrophication, and is the main oxygen consuming pollutant in water, which is toxic to fish and some aquatic organisms.
The main harmful effect of ammonia nitrogen on aquatic organisms is free ammonia, whose toxicity is dozens of times greater than that of ammonium salt, and increases with the increase of alkalinity. Ammonia nitrogen toxicity is closely related to the pH value and water temperature of the pool water, in general, the higher the pH value and water temperature, the stronger the toxicity.
Two approximate sensitivity colorimetric methods commonly used to determine ammonia are the classical Nessler reagent method and the phenol-hypochlorite method. Titrations and electrical methods are also commonly used to determine ammonia; When the ammonia nitrogen content is high, the distillation titration method can also be used. (National standards include Nath’s reagent method, salicylic acid spectrophotometry, distillation – titration method)
2.Physical and chemical nitrogen removal process
① Chemical precipitation method
Chemical precipitation method, also known as MAP precipitation method, is to add magnesium and phosphoric acid or hydrogen phosphate to the wastewater containing ammonia nitrogen, so that NH4+ in the wastewater reacts with Mg+ and PO4- in an aqueous solution to generate ammonium magnesium phosphate precipitation, the molecular formula is MgNH4P04.6H20, so as to achieve the purpose of removing ammonia nitrogen. Magnesium ammonium phosphate, commonly known as struvite, can be used as compost, soil additive or fire retardant for building structural products. The reaction equation is as follows:
Mg++ NH4 + + PO4 – = MgNH4P04
The main factors affecting the treatment effect of chemical precipitation are pH value, temperature, ammonia nitrogen concentration and molar ratio (n(Mg+) : n(NH4+) : n(P04-)). The results show that when pH value is 10 and molar ratio of magnesium, nitrogen and phosphorus is 1.2:1:1.2, the treatment effect is better.
Using magnesium chloride and disodium hydrogen phosphate as precipitating agents, the results show that the treatment effect is better when the pH value is 9.5 and the molar ratio of magnesium, nitrogen and phosphorus is 1.2:1:1.
The results show that MgC12+Na3PO4.12H20 is superior to other precipitating agent combinations. When the pH value is 10.0, the temperature is 30℃, n(Mg+) : n(NH4+) : n(P04-)= 1:1:1, the mass concentration of ammonia nitrogen in the wastewater after stirring for 30min is reduced from 222mg/L before treatment to 17mg/L, and the removal rate is 92.3%.
The chemical precipitation method and liquid membrane method were combined for the treatment of high concentration industrial ammonia nitrogen wastewater. Under the conditions of optimization of precipitation process, the removal rate of ammonia nitrogen reached 98.1%, and then further treatment with liquid film method reduced the ammonia nitrogen concentration to 0.005g/L, reaching the national first-class emission standard.
The removal effect of divalent metal ions (Ni+, Mn+, Zn+, Cu+, Fe+) other than Mg+ on ammonia nitrogen under the action of phosphate was investigated. A new process of CaSO4 precipitation-MAP precipitation was proposed for ammonium sulfate wastewater. The results show that the traditional NaOH regulator can be replaced by lime.
The advantage of chemical precipitation method is that when the concentration of ammonia nitrogen wastewater is high, the application of other methods is limited, such as biological method, break point chlorination method, membrane separation method, ion exchange method, etc. At this time, chemical precipitation method can be used for pre-treatment. The removal efficiency of chemical precipitation method is better, and it is not limited by temperature, and the operation is simple. The precipitated sludge containing magnesium ammonium phosphate can be used as a composite fertilizer to realize waste utilization, thus offsetting part of the cost; If it can be combined with some industrial enterprises that produce phosphate wastewater and enterprises that produce salt brine, it can save pharmaceutical costs and facilitate large-scale application.
The disadvantage of chemical precipitation method is that due to the restriction of solubility product of ammonium magnesium phosphate, after the ammonia nitrogen in wastewater reaches a certain concentration, the removal effect is not obvious and the input cost is greatly increased. Therefore, chemical precipitation method should be used in combination with other methods suitable for advanced treatment. The amount of reagent used is large, the sludge produced is large, and the treatment cost is high. The introduction of chloride ions and residual phosphorus during the dosing of chemicals can easily cause secondary pollution.
Wholesale Aluminium Sulfate Manufacturer and Supplier | EVERBRIGHT (cnchemist.com)
Wholesale Dibasic Sodium Phosphate Manufacturer and Supplier | EVERBRIGHT (cnchemist.com)
②blow off method
The removal of ammonia nitrogen by blowing method is to adjust the pH value to alkaline, so that the ammonia ion in the wastewater is converted to ammonia, so that it mainly exists in the form of free ammonia, and then the free ammonia is taken out of the wastewater through the carrier gas, so as to achieve the purpose of removing ammonia nitrogen. The main factors affecting the blowing efficiency are pH value, temperature, gas-liquid ratio, gas flow rate, initial concentration and so on. At present, the blow-off method is widely used in the treatment of wastewater with high concentration of ammonia nitrogen.
The removal of ammonia nitrogen from landfill leachate by blow-off method was studied. It was found that the key factors controlling the efficiency of blow-off were temperature, gas-liquid ratio and pH value. When the water temperature is greater than 2590, the gas-liquid ratio is about 3500, and the pH is about 10.5, the removal rate can reach more than 90% for the landfill leachate with the ammonia nitrogen concentration as high as 2000-4000mg/L. The results show that when pH=11.5, stripping temperature is 80cC and stripping time is 120min, the removal rate of ammonia nitrogen in wastewater can reach 99.2%.
The blowing-off efficiency of high concentration ammonia nitrogen wastewater was carried out by countercurrent blowing-off tower. The results showed that the blowing-off efficiency increased with the increase of pH value. The larger the gas-liquid ratio is, the greater the driving force of ammonia stripping mass transfer is, and the stripping efficiency also increases.
The removal of ammonia nitrogen by blowing method is effective, easy to operate and easy to control. The blown ammonia nitrogen can be used as an absorber with sulfuric acid, and the generated sulfuric acid money can be used as fertilizer. Blow-off method is a commonly used technology for physical and chemical nitrogen removal at present. However, the blow-off method has some disadvantages, such as frequent scaling in the blow-off tower, low ammonia nitrogen removal efficiency at low temperature, and secondary pollution caused by the blow-off gas. Blow-off method is generally combined with other ammonia nitrogen wastewater treatment methods to pretreat high-concentration ammonia nitrogen wastewater.
③Break point chlorination
The mechanism of ammonia removal by break point chlorination is that chlorine gas reacts with ammonia to produce harmless nitrogen gas, and N2 escapes into the atmosphere, making the reaction source continue to the right. The reaction formula is:
HOCl NH4 + + 1.5 – > 0.5 N2 H20 H++ Cl – 1.5 + 2.5 + 1.5)
When chlorine gas is transferred into the wastewater to a certain point, the content of free chlorine in the water is low, and the concentration of ammonia is zero. When the amount of chlorine gas passes the point, the amount of free chlorine in the water will increase, therefore, the point is called the break point, and the chlorination in this state is called the break point chlorination.
The break point chlorination method is used to treat the drilling wastewater after ammonia nitrogen blowing, and the treatment effect is directly affected by the pretreatment ammonia nitrogen blowing process. When 70% of the ammonia nitrogen in the wastewater is removed by blowing process and then treated by break point chlorination, the mass concentration of ammonia nitrogen in the effluent is less than 15mg/L. Zhang Shengli et al. took simulated ammonia nitrogen wastewater with a mass concentration of 100mg/L as the research object, and the research results showed that the main and secondary factors affecting the removal of ammonia nitrogen by oxidation of sodium hypochlorite were the quantity ratio of chlorine to ammonia nitrogen, reaction time, and pH value.
The break point chlorination method has high nitrogen removal efficiency, the removal rate can reach 100%, and the ammonia concentration in wastewater can be reduced to zero. The effect is stable and not affected by temperature; Less investment equipment, rapid and complete response; It has the effect of sterilization and disinfection on water body. The scope of application of the break point chlorination method is that the concentration of ammonia nitrogen wastewater is less than 40mg/L, so the break point chlorination method is mostly used for the advanced treatment of ammonia nitrogen wastewater. The requirement of safe use and storage is high, the cost of treatment is high, and the by-products chloramines and chlorinated organics will cause secondary pollution.
④catalytic oxidation method
Catalytic oxidation method is through the action of catalyst, under a certain temperature and pressure, through air oxidation, organic matter and ammonia in sewage can be oxidized and decomposed into harmless substances such as CO2, N2 and H2O, to achieve the purpose of purification.
The factors affecting the effect of catalytic oxidation are catalyst characteristics, temperature, reaction time, pH value, ammonia nitrogen concentration, pressure, stirring intensity and so on.
The degradation process of ozonated ammonia nitrogen was studied. The results showed that when pH value increased, a kind of HO radical with strong oxidation ability was produced, and the oxidation rate was significantly accelerated. Studies show that ozone can oxidize ammonia nitrogen to nitrite and nitrite to nitrate. The concentration of ammonia nitrogen in water decreases with the increase of time, and the removal rate of ammonia nitrogen is about 82%. CuO-Mn02-Ce02 was used as a composite catalyst to treat ammonia nitrogen wastewater. The experimental results show that the oxidation activity of the newly prepared composite catalyst is significantly improved, and the suitable process conditions are 255℃, 4.2MPa and pH=10.8. In the treatment of ammonia nitrogen wastewater with an initial concentration of 1023mg/L, the removal rate of ammonia nitrogen can reach 98% within 150min, reaching the national secondary (50mg/L) discharge standard.
The catalytic performance of zeolite supported TiO2 photocatalyst was investigated by studying the degradation rate of ammonia nitrogen in sulfuric acid solution. The results show that the optimal dosage of Ti02/ zeolite photocatalyst is 1.5g/L and the reaction time is 4h under ultraviolet irradiation. The removal rate of ammonia nitrogen from wastewater can reach 98.92%. The removal effect of high iron and nano-chin dioxide under ultraviolet light on phenol and ammonia nitrogen was studied. The results show that the removal rate of ammonia nitrogen is 97.5% when pH=9.0 is applied to the ammonia nitrogen solution with the concentration of 50mg/L, which is 7.8% and 22.5% higher than that of high iron or Chine dioxide alone.
Catalytic oxidation method has the advantages of high purification efficiency, simple process, small bottom area, etc., and is often used to treat high-concentration ammonia nitrogen wastewater. The application difficulty is how to prevent the loss of catalyst and corrosion protection of equipment.
⑤electrochemical oxidation method
Electrochemical oxidation method refers to the method of removing pollutants in water by using electrooxidation with catalytic activity. The influencing factors are current density, inlet flow rate, outlet time and point solution time.
The electrochemical oxidation of ammonia-nitrogen wastewater in a circulating flow electrolytic cell was studied, where the positive is Ti/Ru02-TiO2-Ir02-SnO2 network electricity and the negative is Ti network electricity. The results show that when the chloride ion concentration is 400mg/L, the initial ammonia nitrogen concentration is 40mg/L, the influent flow rate is 600mL/min, the current density is 20mA/cm, and the electrolytic time is 90min, the ammonia nitrogen removal rate is 99.37%. It shows that electrolytic oxidation of ammonia-nitrogen wastewater has a good application prospect.
3. Biochemical nitrogen removal process
①the whole nitrification and denitrification
Whole-process nitrification and denitrification is a kind of biological method which has been widely used for a long time at present. It converts ammonia nitrogen in wastewater into nitrogen through a series of reactions such as nitrification and denitrification under the action of various microorganisms, so as to achieve the purpose of wastewater treatment. The process of nitrification and denitrification to remove ammonia nitrogen needs to go through two stages:
Nitrification reaction: The nitrification reaction is completed by aerobic autotrophic microorganisms. In the aerobic state, inorganic nitrogen is used as the nitrogen source to convert NH4+ into NO2-, and then it is oxidized to NO3-. The nitrification process can be divided into two stages. In the second stage, nitrite is converted to nitrate (NO3-) by nitrifying bacteria, and nitrite is converted to nitrate (NO3-) by nitrifying bacteria.
Denitrification reaction: Denitrification reaction is the process in which denitrifying bacteria reduce nitrite nitrogen and nitrate nitrogen to gaseous nitrogen (N2) in the state of hypoxia. Denitrifying bacteria are heterotrophic microorganisms, most of which belong to amphictic bacteria. In the state of hypoxia, they use oxygen in nitrate as electron acceptor and organic matter (BOD component in sewage) as electron donor to provide energy and be oxidized and stabilized.
The whole process nitrification and denitrification engineering applications mainly include AO, A2O, oxidation ditch, etc., which is a more mature method used in biological nitrogen removal industry.
The whole nitrification and denitrification method has the advantages of stable effect, simple operation, no secondary pollution and low cost. This method also has some drawbacks, such as the carbon source must be added when the C/N ratio in the wastewater is low, the temperature requirement is relatively strict, the efficiency is low at low temperature, the area is large, the oxygen demand is large, and some harmful substances such as heavy metal ions have a pressing effect on microorganisms, which need to be removed before the biological method is carried out. In addition, the high concentration of ammonia nitrogen in the wastewater also has an inhibitory effect on the nitrification process. Therefore, pretreatment should be carried out before the treatment of high-concentration ammonia nitrogen wastewater so that the concentration of ammonia nitrogen wastewater is less than 500mg/L. The traditional biological method is suitable for the treatment of low concentration ammonia nitrogen wastewater containing organic matter, such as domestic sewage, chemical wastewater, etc.
②Simultaneous nitrification and denitrification (SND)
When nitrification and denitrification are carried out together in the same reactor, it is called simultaneous digestion denitrification (SND). The dissolved oxygen in wastewater is limited by the diffusion rate to produce a dissolved oxygen gradient in the microenvironment area on the microbial floc or biofilm, which makes the dissolved oxygen gradient on the outer surface of the microbial floc or biofilm conducive to the growth and propagation of aerobic nitrifying bacteria and ammoniating bacteria. The deeper into the floc or membrane, the lower the concentration of dissolved oxygen, resulting in anoxic zone where denitrifying bacteria dominate. Thus forming simultaneous digestion and denitrification process. The factors affecting simultaneous digestion and denitrification are PH value, temperature, alkalinity, organic carbon source, dissolved oxygen and sludge age.
Simultaneous nitrification/denitrification existed in the Carrousel oxidation ditch, and the concentration of dissolved oxygen between the aerated impeller in the Carrousel oxidation ditch gradually decreased, and the dissolved oxygen in the lower part of the Carrousel oxidation ditch was lower than that in the upper part. The formation and consumption rates of nitrate nitrogen in each part of the channel are almost equal, and the concentration of ammonia nitrogen in the channel is always very low, which indicates that the nitrification and denitrification reactions occur simultaneously in the Carrousel oxidation channel.
The study on the treatment of domestic sewage shows that the higher the CODCr, the more complete the denitrification and the better the TN removal. The effect of dissolved oxygen on simultaneous nitrification and denitrification is great. When the dissolved oxygen is controlled at 0.5~2mg/L, the total nitrogen removal effect is good. At the same time, the nitrification and denitrification method saves the reactor, shorters the reaction time, has low energy consumption, saves investment, and is easy to keep the pH value stable.
③Short-range digestion and denitrification
In the same reactor, ammonia oxidizing bacteria are used to oxidize ammonia to nitrite under aerobic conditions, and then nitrite is directly denitrified to produce nitrogen with organic matter or external carbon source as electron donor under hypoxia conditions. The influence factors of short-range nitrification and denitrification are temperature, free ammonia, pH value and dissolved oxygen.
Effect of temperature on short-range nitrification of municipal sewage without seawater and municipal sewage with 30% seawater. The experimental results show that: for the municipal sewage without seawater, increasing the temperature is conducive to achieving short-range nitrification. When the proportion of seawater in domestic sewage is 30%, short-range nitrification can be achieved better under medium temperature conditions. Delft University of Technology developed the SHARON process, the use of high temperature (about 30-4090) is conducive to the proliferation of nitrite bacteria, so that nitrite bacteria lose competition, while by controlling the age of the sludge to eliminate nitrite bacteria, so that the nitrification reaction in the nitrite stage.
Based on the difference in oxygen affinity between nitrite bacteria and nitrite bacteria, the Gent Microbial Ecology Laboratory developed the OLAND process to achieve the accumulation of nitrite nitrogen by controlling dissolved oxygen to eliminate nitrite bacteria.
The pilot test results of the treatment of coking wastewater by short-range nitrification and denitrification show that when the influent COD, ammonia nitrogen,TN and phenol concentrations are 1201.6,510.4,540.1 and 110.4mg/L, the average effluent COD, ammonia nitrogen,TN and phenol concentrations are 197.1,14.2,181.5 and 0.4mg/L, respectively. The corresponding removal rates were 83.6%,97.2%, 66.4% and 99.6%, respectively.
Short-range nitrification and denitrification process does not go through the nitrate stage, saving the carbon source required for biological nitrogen removal. It has certain advantages for ammonia nitrogen wastewater with low C/N ratio. Short-range nitrification and denitrification has the advantages of less sludge, short reaction time and saving reactor volume. However, short-range nitrification and denitrification require stable and lasting accumulation of nitrite, so how to effectively inhibit the activity of nitrifying bacteria becomes the key.
④ Anaerobic ammonia oxidation
Anaerobic ammoxidation is a process of direct oxidation of ammonia nitrogen to nitrogen by autotrophic bacteria under the condition of hypoxia, with nitrous nitrogen or nitrous nitrogen as electron acceptor.
The effects of temperature and PH on the biological activity of anammoX were studied. The results showed that the optimal reaction temperature was 30℃ and pH value was 7.8. The feasibility of anaerobic ammoX reactor for treating high salinity and high concentration nitrogen wastewater was studied. The results showed that high salinity significantly inhibited anammoX activity, and this inhibition was reversible. The anaerobic ammox activity of the unacclimated sludge was 67.5% lower than that of the control sludge under the salinity of 30g.L-1(NaC1). The anammoX activity of the acclimated sludge was 45.1% lower than that of the control. When the acclimated sludge was transferred from a high salinity environment to a low salinity environment (no brine), the anaerobic ammoX activity was increased by 43.1%. However, the reactor is prone to function decline when it runs in high salinity for a long time.
Compared with the traditional biological process, anaerobic ammoX is a more economical biological nitrogen removal technology with no additional carbon source, low oxygen demand, no need for reagents to neutralize, and less sludge production. The disadvantages of anaerobic ammox are that the reaction speed is slow, the reactor volume is large, and the carbon source is unfavorable to anaerobic amMOX, which has practical significance for solving the ammonia nitrogen wastewater with poor biodegradability.
4.separation and adsorption nitrogen removal process
① membrane separation method
Membrane separation method is to use the selective permeability of the membrane to selectively separate the components in the liquid, so as to achieve the purpose of ammonia nitrogen removal. Including reverse osmosis, nanofiltration, deammoniating membrane and electrodialysis. The factors affecting membrane separation are membrane characteristics, pressure or voltage, pH value, temperature and ammonia nitrogen concentration.
According to the water quality of ammonia nitrogen wastewater discharged by rare earth smelter, the reverse osmosis experiment was carried out with NH4C1 and NaCI simulated wastewater. It was found that under the same conditions, reverse osmosis has a higher removal rate of NaCI, while NHCl has a higher water production rate. The removal rate of NH4C1 is 77.3% after reverse osmosis treatment, which can be used as pretreatment of ammonia nitrogen wastewater. Reverse osmosis technology can save energy, good thermal stability, but chlorine resistance, pollution resistance is poor.
A biochemical nanofiltration membrane separation process was used to treat the landfill leachate, so that 85%~90% of the permeable liquid was discharged according to the standard, and only 0%~15% of the concentrated sewage liquid and mud were returned to the garbage tank. Ozturki et al. treated the landfill leachate of Odayeri in Turkey with nanofiltration membrane, and the removal rate of ammonia nitrogen was about 72%. Nanofiltration membrane requires lower pressure than reverse osmosis membrane, easy to operate.
The ammonia-removing membrane system is generally used in the treatment of wastewater with high ammonia nitrogen. The ammonia nitrogen in the water has the following balance: NH4- +OH-= NH3+H2O in operation, the ammonia-containing wastewater flows in the shell of the membrane module, and the acid-absorbing liquid flows in the pipe of the membrane module. When the PH of the wastewater increases or the temperature rises, the equilibrium will shift to the right, and the ammonium ion NH4- becomes the free gaseous NH3. At this time, gaseous NH3 can enter the acid absorption liquid phase in the pipe from the waste water phase in the shell through the micropores on the surface of the hollow fiber, which is absorbed by the acid solution and immediately becomes ionic NH4-. Keep the PH of the wastewater above 10, and the temperature above 35 ° C (below 50 ° C), so that the NH4 in the wastewater phase will continuously become NH3 to the absorption liquid phase migration. As a result, the concentration of ammonia nitrogen in the wastewater side decreased continuously. The acid absorption liquid phase, because there is only acid and NH4-, forms a very pure ammonium salt, and reaches a certain concentration after continuous circulation, which can be recycled. On the one hand, the use of this technology can greatly improve the removal rate of ammonia nitrogen in wastewater, and on the other hand, it can reduce the total operating cost of wastewater treatment system.
②electrodialysis method
Electrodialysis is a method of removing dissolved solids from aqueous solutions by applying a voltage between the membrane pairs. Under the action of voltage, the ammonia ions and other ions in the ammonia-nitrogen wastewater are enriched through the membrane in the ammonia-containing concentrated water, so as to achieve the purpose of removal.
The electrodialysis method was used to treat inorganic wastewater with high concentration of ammonia nitrogen and achieved good results. For 2000-3000mg /L ammonia nitrogen wastewater, the removal rate of ammonia nitrogen can be more than 85%, and the concentrated ammonia water can be obtained by 8.9%. The amount of electricity consumed during the operation of electrodialysis is proportional to the amount of ammonia nitrogen in the wastewater. Electrodialysis treatment of wastewater is not limited by pH value, temperature and pressure, and it is easy to operate.
The advantages of membrane separation are high recovery of ammonia nitrogen, simple operation, stable treatment effect and no secondary pollution. However, in the treatment of high-concentration ammonia nitrogen wastewater, except for the deammoniated membrane, other membranes are easy to scale and clog, and regeneration and backwashing are frequent, increasing the treatment cost. Therefore, this method is more suitable for pretreatment or low-concentration ammonia nitrogen wastewater.
③ Ion exchange method
Ion exchange method is a method to remove ammonia nitrogen from wastewater by using materials with strong selective adsorption of ammonia ions. The commonly used adsorption materials are activated carbon, zeolite, montmorillonite and exchange resin. Zeolite is a kind of silico-aluminate with three-dimensional spatial structure, regular pore structure and holes, among which clinoptilolite has a strong selective adsorption capacity for ammonia ions and low price, so it is commonly used as an adsorption material for ammonia nitrogen wastewater in engineering. The factors affecting the treatment effect of clinoptilolite include particle size, influent ammonia nitrogen concentration, contact time, pH value and so on.
The adsorption effect of zeolite on ammonia nitrogen is obvious, followed by ranite, and the effect of soil and ceramisite is poor. The main way to remove ammonia nitrogen from zeolite is ion exchange, and the physical adsorption effect is very small. The ion exchange effect of ceramite, soil and ranite is similar to the physical adsorption effect. The adsorption capacity of the four fillers decreased with the increase of temperature in the range of 15-35℃, and increased with the increase of pH value in the range of 3-9. The adsorption equilibrium was reached after 6h oscillation.
The feasibility of removing ammonia nitrogen from landfill leachate by zeolite adsorption was studied. The experimental results show that each gram of zeolite has a limited adsorption potential of 15.5mg ammonia nitrogen, when the zeolite particle size is 30-16 mesh, the removal rate of ammonia nitrogen reaches 78.5%, and under the same adsorption time, dosage and zeolite particle size, the higher the influent ammonia nitrogen concentration, the higher the adsorption rate, and it is feasible for zeolite as an adsorbent to remove ammonia nitrogen from the leachate. At the same time, it is pointed out that the adsorption rate of ammonia nitrogen by zeolite is low, and it is difficult for zeolite to reach saturation adsorption capacity in practical operation.
The removal effect of biological zeolite bed on nitrogen, COD and other pollutants in simulated village sewage was studied. The results show that the removal rate of ammonia nitrogen by biological zeolite bed is more than 95%, and the removal of nitrate nitrogen is greatly affected by the hydraulic residence time.
The ion exchange method has the advantages of small investment, simple process, convenient operation, insensitivity to poison and temperature, and reuse of zeolite by regeneration. However, when treating high-concentration ammonia nitrogen wastewater, the regeneration is frequent, which brings inconvenience to the operation, so it needs to be combined with other ammonia nitrogen treatment methods, or used to treat low-concentration ammonia nitrogen wastewater.
Wholesale 4A Zeolite Manufacturer and Supplier | EVERBRIGHT (cnchemist.com)
Post time: Jul-10-2024
