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Removal of Ammonia Nitrogen from Evaporated Condensate by New Membrane Contactor

Updated:2020-10-15 14:27

The treatment of evaporated condensate containing ammonia nitrogen is a general difficulty problem for manufacturing enterprises of amino acid, medicine, food, and chemical industries. In these industries, there is a high level of ammonia nitrogen in the evaporated condensate obtained, whether it is for evaporation of products in the production process or for zero-discharge evaporation process of wastewater. How to effectively remove ammonia nitrogen from evaporated condensate is a common concern for these types of enterprises.
 
Taking amino acid industry as an example, the last process of amino acid production is evaporation crystallization, and there is a large amount of free ammonia nitrogen in the evaporated condensate. Free ammonia nitrogen is a volatile substance. When PH > 9, ammonia nitrogen in water exists in the form of NH3. When PH < 9, most of ammonia nitrogen exists in the form of NH4+ with the content up to 2000 ~ 4000ppm. In the chemical industry, the index is even higher. At this time, it is not appropriate to remove ammonia nitrogen by adding chlorine at break point, or by biochemical or blowing off method. Break point chlorination is more suitable for the treatment of low concentration ammonia nitrogen. Water consumption and floor coverage are high in biochemical treatment. For stripping tower blowing off method, the starting investment, operation cost and floor coverage are all very high, and the treatment effect is not very good.
 
The unique membrane contactor technology for removal of ammonia nitrogen developed by Guo Chu Technology (Xiamen) Co., Ltd. can remove more than 90% ammonia nitrogen from condensate, and the energy consumption is far lower than that of traditional blowing off process.
 
Membrane contactor technology is a newly developed process for removal of ammonia nitrogen. Its basic principle is to convert ammonia nitrogen into non-ionic ammonia. The non-ionic ammonia in raw water is absorbed into ammonium sulfate by dilute acid solution through membrane contactor. After removing ammonia nitrogen, the condensate can be discharged or recycled.
 
Ammonia nitrogen has the following equilibrium in water:
 
NH4++OH←→ NH3↑+H2O
 
When the PH of the water increases or the temperature rises, the above equilibrium will shift to the right, and the ammonium ion NH4+ will become free gaseous NH3, which can pass through the micro pores on the surface of the hollow fiber from the raw water phase in the housing to the acid absorption liquid phase in the tube, and then become ionic NH4+ again when absorbed by the acid.
 
By keeping the PH of the water above 10 and the temperature above 35°C (below 45°C), the NH4+ in the water phase will continuously become NH3 and migrate to the absorption liquid phase. As a result, the concentration of ammonia nitrogen in the raw water side will decrease continuously until it reaches the user's satisfactory standard; Since the acid absorption liquid phase only contains acid and NH4+, it forms very pure ammonium salt, which can be recycled after it reaches a certain concentration by continuous circulation.
 
                                
 
Compared with the traditional ammonia nitrogen removal technologies such as ammonia evaporation, blowing off method and gas extraction method, the membrane contactor deamination technology of Guo Chu Technology (Xiamen) Co., Ltd. has the following advantages:
 
1. The ammonia nitrogen removal efficiency is high, and the removal rate can be accurately controlled;
 
2. The process flow is simple, the operation and maintenance is easy, and the treatment effect is stable;
 
3. Membrane contactor deamination technology combines the steps of deamination and acid absorption into one, which greatly reduces the area occupied by the equipment;
 
4. The energy consumption is only about one tenth of that of blowing off method, and the operation cost is very low;
 
5. With modular design, the equipment is easy to move, expand and upgrade;
 
6. Since the operating environment is closed, there is no ammonia leakage, clean production is achieved;
 
7. There is no secondary pollution and the water consumption and gas consumption are greatly reduced;
 
8. The purity of the by-products is high, which has certain economic benefits;
 
At present, the technology of membrane contactor for removal of ammonia nitrogen can be used in the following fields:
 
Deamination of Hydrometallurgical Wastewater:
 
This application covers the following industries: nonferrous metallurgy, new materials (lithium batteries, microelectronics, etc.), rare earth, PCB, catalyst, inorganic chemical industry, desulfurized wastewater, etc.
 
Raw Water Characteristics: The content of ammonia nitrogen in raw water is different (50 ~ 10000 ppm), COD content is very low (generally only 30 ~ 50 ppm), PH value distribution range is wide (1 ~ 13), and suspended solids are less.
 
Deamination of Evaporated Condensate:
 
The industry scope covered by this application mainly includes: amino acid, chemical fertilizer, pesticide, petrochemical, printing and dyeing, biochemical, fine chemical, zero discharge and other condensate after evaporation concentration and evaporation crystallization process.
 
Raw Water Characteristics: ammonia nitrogen content is moderate (800 ~ 4000ppm), COD content is wide (200 ~ 10000ppm), PH is alkaline, suspended solids are less, and the temperature is high.
 
Deamination of Coal Chemical Wastewater:
 
The industry scope covered by this application mainly includes: coking, new coal chemical industry, chemical fertilizer (nitrogen fertilizer), etc.
 
Raw Water Characteristics: ammonia nitrogen content is high (600 ~ 3000ppm), COD content is high (1000 ~ 6000ppm), PH is alkaline, and there are suspended solids.
 
Deamination of High COD Wastewater:
 
The industry scope covered by this application mainly includes: fine chemical, pharmaceutical, landfill leachate, etc.
 
Raw Water Characteristics: ammonia nitrogen content is high (1000 ~ 20000 ppm), COD content is high (20000 ~ 30000 ppm).

Guo Chu Technology (Xiamen) Co., Ltd. is a high-tech enterprise, which focus on membrane separation technology and is committed to the promotion of new separation technology.It has rich experiences in the application of special membranes in medicine, chemical industry, food, beverage, petroleum, petrochemical, nuclear energy and other industries. It can develop membrane separation technology and equipment suitable for specific separation requirements according to the process requirements of customers. It also specializes in the whole process services, from preliminary technology assessment, process technology confirmation, experimental R&D validation and industrial system integration.
 
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