Recovery system for ammonia nitrogen in sewage

Abstract

The utility model relates to the technical field of sewage treatment, and discloses an ammonia nitrogen recovery system for sewage, which comprises a reaction tank (1), a spray pipe (2), an upper water distributor (3), an ammonia nitrogen adsorption material (4), a lower water distributor (5), a water inlet pump (8), a backwashing pump (12), an acid liquid storage tank (18), an acid adding pump (19), an alkali liquid storage tank (20), an alkali adding pump (21) and a water production tank (22). Different packing densities are set, so that the flow speed of sewage passing through the ammonia nitrogen adsorption material at the lower layer is higher than that of the ammonia nitrogen adsorption material at the upper layer, vacuum and back pressure are generated locally, the blockage condition of gaps among the ammonia nitrogen adsorption materials (4) is effectively relieved, the back washing period of the ammonia nitrogen adsorption materials (4) is prolonged, the maintenance cost is reduced, and the adsorption efficiency is improved; the ammonia nitrogen adsorption material in the system can adsorb ammonium ions and free ammonia in the sewage, and finally recycling of ammonia nitrogen is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection water treatment, and relates to an ammonia wastewater treatment process, specifically an ammonia nitrogen recovery system for sewage. Background Technique

[0002] With the continuous development of social economy and the acceleration of industrial production, the discharge of industrial sewage and waste gas has gradually become one of the hot topics of discussion. A large amount of industrial wastewater has brought serious pollution to the surrounding environment, interfering with people's daily lives and seriously affecting the survival of natural organisms. As one of the important pollutants, ammonia nitrogen wastewater has caused great harm to the environment and affected people's normal lives. Ammonia nitrogen is an important part of the nitrogen cycle in the environment, and nitrogen and phosphorus elements are also the main causes of water eutrophication. Excessive ammonia nitrogen entering the water body will lead to water eutrophication, reduce water quality and affect the ornamental value of the water body. Moreover, the nitrates and nitrites generated by oxidation will affect the survival of aquatic organisms and human health. Therefore, it is very necessary to adopt effective water treatment technologies to treat ammonia nitrogen wastewater and reduce environmental pollution.

[0003] At present, many studies on ammonia nitrogen wastewater treatment technologies have been carried out at home and abroad. Stripping method, air stripping method, biological method (AA / O method) and chemical precipitation method are mostly used to treat high-concentration ammonia nitrogen wastewater.

[0004] Stripping method. Stripping is suitable for the recovery of large amounts of water with medium and low concentrations of ammonia. Water enters the top of the tower through a heat exchanger and sprays downwards, while steam flows upwards countercurrently from the bottom to contact it. Once the pressure of the water vapor is higher than the external pressure, the water will boil, thus accelerating the process of transferring volatile ammonia gas to the gas phase. The water vapor passes through the water layer, and the water and bubbles form a free surface. The volatile ammonia gas evaporates into the bubbles and is carried out of the water surface through the bubbles, and finally collected and entered the recovery system.

[0005] Air stripping method. The treatment of ammonia nitrogen wastewater by the air stripping method mainly selects an influent ammonia nitrogen concentration of 1000 mg / L, an air-water ratio of 260:1, a pH value of 7-11, a water volume of 350 L / h, and a blowing time of 1-8 h. A higher OH - concentration in the water reacts to form NH 3 , realizing air stripping. Therefore, under the same conditions, the size of the pH value will determine the air stripping effect. The larger the value, the better the effect, and the longer the time, the more NH 3 will be removed.

[0006] Biological method. The biological method is an important water treatment technology currently used in China to treat ammonia nitrogen wastewater. Processes such as the AA / O process can all play a role in removing NH 3 -N in the wastewater. The principle of this method is to convert NH 3 -N in the ammonia nitrogen wastewater into NO2- -N, and then oxidize NO 2- -N to NO 3- -N, and then convert NO 3- -N into NO 2 -N, and finally convert it into N 2 . The AA / O process can remove the BOD in water 5 to meet the discharge standards, and at the same time treat the COD and NH 3 -N in the wastewater, thereby reducing industrial pollution.

[0007] Chemical precipitation method. The chemical precipitation method mainly involves adding a reagent containing Mg 2+ and PO 3- ions to the ammonia-nitrogen wastewater, reacting with the NH 4 + in the wastewater to form a complex salt MgNH 4 PO 4 ·6H 2 O, commonly known as "struvite", to achieve the removal of ammonia nitrogen in industrial wastewater. Among them, MgNH 4 PO 4 ·6H 2 O can also be used as a compound fertilizer required by crops to achieve the recycling of nitrogen and phosphorus.

[0008] The reasons for the low denitrification efficiency of traditional stripping or air stripping methods are as follows: First, the traditional treatment methods only have simple physical effects without chemical effects, so it is impossible to convert all ionic ammonium into molecular ammonia, nor can organic nitrogen be converted into ammonia nitrogen; Second, this method cannot break the strong binding force between ammonia molecules and water molecules and break the hydrogen bond between bound ammonia molecules and water molecules; In addition, traditional air stripping or stripping methods cannot control the contact reaction time between air and water, and cannot achieve stable treatment effects. Although the chemical precipitation method can achieve the recycling of nitrogen and phosphorus, it often has high construction costs, high treatment costs, harsh operating conditions, unsatisfactory denitrification effects, and low recycling efficiency. Therefore, researchers have been continuously exploring and studying other methods for ammonia nitrogen treatment and recycling with lower costs, stable operation, and higher recycling efficiency. Summary of the Utility Model

[0009] The purpose of the present utility model is to provide an ammonia nitrogen recovery system for sewage with low operation and maintenance costs, stable performance, and high recovery efficiency.

[0010] To achieve the above object, the present utility model adopts the following technical solutions: An ammonia nitrogen recovery system for sewage, comprising a reaction tank (1), a spray pipe (2), an upper water distributor (3), an ammonia nitrogen adsorption material (4), a lower water distributor (5), a feed water pump (8), a backwash pump (12), an acid storage tank (18), an acid adding pump (19), an alkali storage tank (20), an alkali adding pump (21), and a product water tank (22). A spray pipe (2) is provided at the top inside the reaction tank (1), an upper water distributor (3) is provided 0.5 - 1.5 m below the spray pipe (2), a lower water distributor (5) is provided at the bottom inside the reaction tank (1), an ammonia nitrogen adsorption material (4) is installed within the range between the upper water distributor (3) and the lower water distributor (5), an exhaust pipe (6) is provided at the top outside the reaction tank (1), an external water inlet pipe (7) is connected to the internal upper water distributor (3) through a feed water pump (8) and a water inlet valve (9), an external backwash water inlet pipe (11) is connected to an interface on one side of the bottom of the reaction tank (1) through a backwash pump (12) and a backwash water inlet valve (13), a backwash water outlet pipe (10) is connected to the water inlet pipe (7) after the water inlet valve (9), a backwash water outlet valve (14) is installed on the backwash water outlet pipe (10), a product water valve (15) and a product water pipe (16) are provided on the other side of the bottom of the reaction tank (1), the product water pipe (16) is communicated to the product water tank (22), an acid storage tank (18) and an alkali storage tank (20) are provided outside the reaction tank (1), the acid storage tank (18) is communicated with the spray pipe (2) through an acid adding pump (19), and the alkali storage tank (20) is connected to the product water tank (22) through an alkali adding pump (21).

[0011] In the present utility model, the ammonia nitrogen adsorption material (4) is divided into upper and lower layers, and the filling density of the upper layer is 1 - 1.5 times that of the lower layer. The reasons for this are as follows: On the one hand, the two layers of ammonia nitrogen adsorption materials can extend the residence time of sewage, enhance the adsorption effect, and thus improve the adsorption efficiency; on the other hand, when sewage passes through ammonia nitrogen adsorption materials with different filling densities, the flow rate of the sewage through the lower layer of ammonia nitrogen adsorption material is faster than that of the upper layer. Therefore, local vacuum and back pressure will be generated, and the pressure difference formed between the upper and lower layers can effectively relieve the blockage of the gaps between the ammonia nitrogen adsorption materials (4), extend the backwashing cycle of the ammonia nitrogen adsorption material (4), and further improve the adsorption efficiency.

[0012] In the present utility model, the upper water distributor (3) is of a U-shaped structure. The gap between the outer circle of the water distributor (3) and the inner wall of the reaction tank (1) is set between 0.3 - 0.8 m, and the top of the water distributor (3) is 1 - 2 m above the ammonia nitrogen adsorption material (4). The reason for this is as follows: During water production, the water distributor (3) functions to distribute and divide water. The sewage entering the system needs to overflow from the top of the water distributor (3) and fall above the ammonia nitrogen adsorption material (4) to ensure sufficient inlet flushing speed. During backwashing, the U-shaped structure of the water distributor (3) has the function of a water decanter or a weir plate, which can effectively prevent the ammonia nitrogen adsorption material (4) from being washed out of the system.

[0013] In the present utility model, the lower water distributor (5) is arranged at the bottom inside the reaction tank (1), and the lower water distributor (5) is 0.1 - 0.2 m below the lower part of the ammonia nitrogen adsorption material (4). The advantage of this is that during backwashing, it plays the role of evenly distributing water and increasing the flow rate, improving the uniformity of backwashing.

[0014] In the present utility model, the spray pipe (2) is arranged at the top inside the reaction tank (1) and is of an annular structure. The advantage of this is that by adjusting the pH, the adsorption effect of the ammonia nitrogen adsorption material (4) on ammonia nitrogen in the sewage can be improved.

[0015] The beneficial effects of the present utility model: The ammonia nitrogen adsorption material (4) can adsorb ammonia nitrogen. During the treatment process, the ammonia nitrogen adsorption material (4) can adsorb ammonium ions (NH 4 + ) and free ammonia (NH 3 ) in the solution, and then the adsorbed ammonium ions and free ammonia are eluted by the eluent, thereby realizing the recovery of ammonia nitrogen. The present utility model has achieved beneficial effects of low maintenance cost, stable performance, and high recovery efficiency. Description of the Drawings

[0016] Figure 1 It is the equipment structure diagram of the present utility model.

[0017] Wherein: (1) reaction tank, (2) spray pipe, (3) upper water distributor, (4) ammonia nitrogen adsorption material, (5) lower water distributor, (6) exhaust pipe, (7) inlet pipe, (8) inlet water pump, (9) inlet water valve, (10) backwash outlet pipe, (11) backwash inlet pipe, (12) backwash pump, (13) backwash inlet water valve, (14) backwash outlet water valve, (15) product water valve, (16) product water pipe, (17) outlet water valve, (18) acid storage tank, (19) acid addition pump, (20) alkali storage tank, (21) alkali addition pump, (22) product water tank. Detailed Embodiment

[0018] To further understand and recognize the structural features and achieved effects of the present utility model, the following is described in conjunction with preferred embodiments and accompanying drawings: As Figure 1 shown, in this embodiment, an ammonia nitrogen recovery system for sewage includes a reaction tank (1), a spray pipe (2), an upper water distributor (3), an ammonia nitrogen adsorption material (4), a lower water distributor (5), a feed water pump (8), a backwash pump (12), an acid storage tank (18), an acid addition pump (19), an alkali storage tank (20), an alkali addition pump (21), and a product water tank (22). A spray pipe (2) is provided at the top inside the reaction tank (1). An upper water distributor (3) is provided 0.5 m below the spray pipe (2). A lower water distributor (5) is provided at the bottom inside the reaction tank (1). An ammonia nitrogen adsorption material (4) is installed within the range between the upper water distributor (3) and the lower water distributor (5). An exhaust pipe (6) is provided at the top outside the reaction tank (1). An external water inlet pipe (7) is connected to the internal upper water distributor (3) through a feed water pump (8) and a water inlet valve (9). An external backwash water inlet pipe (11) is connected to an interface on one side of the bottom of the reaction tank (1) through a backwash pump (12) and a backwash water inlet valve (13). A backwash water outlet pipe (10) is connected to the water inlet pipe (7) behind the water inlet valve (9). A backwash water outlet valve (14) is installed on the backwash water outlet pipe (10). A product water valve (15) and a product water pipe (16) are provided on the other side of the bottom of the reaction tank (1). The product water pipe (16) is connected to the product water tank (22). An acid storage tank (18) and an alkali storage tank (20) are provided outside the reaction tank (1). The acid storage tank (18) is connected to the spray pipe (2) through an acid addition pump (19). The alkali storage tank (20) is connected to the product water tank (22) through an alkali addition pump (21).

[0019] In this embodiment, the ammonia nitrogen adsorption material (4) is divided into upper and lower layers, and the filling density of the upper layer is 1.5 times that of the lower layer.

[0020] In this embodiment, the upper water distributor (3) has a U-shaped structure. The gap between the outer circle of the water distributor (3) and the inner wall of the reaction tank (1) is 0.3 m. The top of the water distributor (3) is 1 m above the ammonia nitrogen adsorption material (4).

[0021] In this embodiment, the lower water distributor (5) is provided at the bottom inside the reaction tank (1), and the lower water distributor (5) is 0.1 m below the lower part of the ammonia nitrogen adsorption material (4).

[0022] In this embodiment, the spray pipe (2) is provided at the top inside the reaction tank (1) and has a circular structure.

[0023] With the continuous progress of urban construction and the continuous expansion of industrial production scale, the daily industrial wastewater discharge increases. Since a large amount of industrial production contains a large number of chemical pollutants, or some pollutants are generated after garbage is stacked for a long time, and some factories do not strictly abide by relevant laws and regulations, discharging randomly, industrial wastewater containing ammonia nitrogen flows into farmland, resulting in a large number of crops being polluted. These polluted crops are inadvertently eaten by people, causing serious harm to human health. Therefore, the invention and promotion of this utility model play a positive and effective role in alleviating and solving the above problems.

Claims

1. A system for recovering ammonia nitrogen from sewage, characterized in that: The invention comprises a reaction tank (1), a spray pipe (2), an upper water distributor (3), an ammonia nitrogen adsorption material (4), a lower water distributor (5), a water inlet pump (8), a backwash pump (12), an acid storage tank (18), an acid addition pump (19), an alkali storage tank (20), an alkali addition pump (21), and a water production tank (22). The spray pipe (2) is arranged at the top of the reaction tank (1), the upper water distributor (3) is arranged 0.5-1.5 m below the spray pipe (2), the lower water distributor (5) is arranged at the bottom of the reaction tank (1), the ammonia nitrogen adsorption material (4) is arranged in the range between the upper water distributor (3) and the lower water distributor (5), the exhaust pipe (6) is arranged at the top outside the reaction tank (1), and the external water inlet pipe (7) is connected to the water inlet pump (8) and the water inlet valve (9). The backwashing water inlet pipe (11) is connected to the interface on one side of the bottom of the reaction tank (1) through the backwashing pump (12) and the backwashing water inlet valve (13). The backwashing water outlet pipe (10) is connected to the water inlet pipe (7) after the water inlet valve (9). The backwashing water outlet pipe (10) is equipped with a backwashing water outlet valve (14). A water production valve (15) and a water production pipe (16) are provided on the other side of the bottom of the reaction tank (1). The water production pipe (16) is connected to a water production tank (22). An acid storage tank (18) and an alkali storage tank (20) are provided outside the reaction tank (1). The acid storage tank (18) is connected to the spray pipe (2) through an acid adding pump (19). The alkali storage tank (20) is connected to the water production tank (22) through an alkali adding pump (21).

2. The ammonia nitrogen recovery system for sewage according to claim 1, characterized in that: The ammonia nitrogen adsorption material (4) is divided into two layers, an upper layer and an lower layer, and the filling density of the upper layer is 1-1.5 times that of the lower layer.

3. The system for recovering ammonia nitrogen from sewage according to claim 1, characterized in that: The upper water distributor (3) is a U-shaped structure, the gap between the outer ring of the upper water distributor (3) and the inner wall of the reaction tank (1) is set between 0.3-0.8m, and the top of the upper water distributor (3) is 1-2m away from the top of the ammonia nitrogen adsorption material (4).

4. The system for recovering ammonia nitrogen from sewage according to claim 1, characterized in that: The lower water distributor (5) is arranged at the bottom of the reaction tank (1), and the lower water distributor (5) is 0.1-0.2 m away from the lower part of the ammonia nitrogen adsorption material (4).

5. The system for recovering ammonia nitrogen from sewage according to claim 1, characterized in that: The spray pipe (2) is arranged at the top of the reaction tank (1) and has a circular ring structure.

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