System and method for softening wastewater

Abstract

The invention discloses a system and method for softening wastewater. The system comprises: a reaction device, an internal circulation pump, a first pipeline mixer, a water ejector, a second pipeline mixer and a sedimentation device. A first partition is arranged in the reaction device, and the first partition divides the reaction device into a water inlet zone and a reaction zone in a horizontal direction. The reaction zone is provided with a perforated water distribution pipe; the internal circulation pump is connected to the water inlet zone; the first pipeline mixer has a sodium hydroxide solution inlet, a wastewater inlet and a first mixed liquid outlet, and the wastewater inlet is connected to the internal circulation pump; the water ejector has a carbon dioxide inlet, a first mixed liquid inlet and a second mixed liquid outlet; the second pipeline mixer has a flocculant inlet, a second mixed liquid inlet and a third mixed liquid outlet, and the third mixed liquid outlet is connected to the perforated water distribution pipe; a separation zone and a sludge settling zone are defined in the sedimentation device along the height direction, and a second partition is arranged in the separation zone, and the second partition divides the separation zone into a water supply zone and a sedimentation zone in a horizontal direction, and the water supply zone is connected to the reaction zone.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and in particular relates to a system and method for softening wastewater. Background Art

[0002] At present, carbon dioxide is often used as a softener in wastewater treatment. It is dissolved in water and reacts with calcium ions in the wastewater to form calcium carbonate precipitation, thereby achieving the purpose of reducing the hardness of the wastewater. Carbon dioxide is usually added to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration tube through a fan. In the tank, carbon dioxide reacts with calcium ions in the wastewater to form calcium carbonate precipitation. However, the perforated aeration tube supplies carbon dioxide so that most of the carbon dioxide diffuses into the air, resulting in a low utilization rate of carbon dioxide. At the same time, due to the large bubbles generated by aeration, mechanical stirring must be set in the softening reaction tank to reduce bubbles, which increases the equipment cost. At the same time, mechanical stirring is required in the tank to prevent calcium carbonate precipitation. The effluent from the softening reaction tank is discharged into the subsequent flocculation tank and precipitation equipment for solid-liquid separation.

[0003] Therefore, the existing equipment for softening wastewater needs to be improved. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one object of the present invention is to provide a system and method for softening wastewater, which can effectively reduce the hardness of wastewater, and has a high carbon dioxide utilization rate and does not require a stirring device, thereby reducing equipment costs while improving the softening effect of wastewater.

[0005] In one aspect of the present invention, the present invention provides a system for softening wastewater. According to an embodiment of the present invention, the system comprises:

[0006] A reaction device, wherein a first partition is provided in the reaction device, wherein the first partition divides the reaction device into a water inlet zone and a reaction zone in a horizontal direction, wherein the lower part of the water inlet zone is connected to the lower part of the reaction zone, and the water inlet zone is provided with a wastewater inlet, and the reaction zone is provided with a perforated water distribution pipe;

[0007] An internal circulation pump, wherein the internal circulation pump is connected to the water inlet area;

[0008] A first pipeline mixer, wherein the first pipeline mixer has a sodium hydroxide solution inlet, a wastewater inlet and a first mixed solution outlet, and the wastewater inlet is connected to the internal circulation pump;

[0009] A water ejector, wherein the water ejector has a carbon dioxide inlet, a first mixed liquid inlet, and a second mixed liquid outlet, wherein the first mixed liquid inlet is connected to the first mixed liquid outlet;

[0010] a second pipeline mixer, the second pipeline mixer having a flocculant inlet, a second mixed liquid inlet and a third mixed liquid outlet, the second mixed liquid inlet is connected to the second mixed liquid outlet, and the third mixed liquid outlet is connected to the perforated water distribution pipe;

[0011] A sedimentation device, wherein a separation zone and a sludge settling zone are defined in the sedimentation device along its height direction, the separation zone is provided with a second partition, the second partition separates the separation zone into a water supply zone and a sedimentation zone in the horizontal direction, the water supply zone is connected to the reaction zone, the sedimentation zone is provided with an inclined plate filler, the top of the sedimentation zone is provided with an overflow port, and the bottom of the sludge settling zone is provided with a sludge discharge port.

[0012] According to the system for softening wastewater of an embodiment of the present invention, a circulating pump is used to supply the wastewater supplied to the water inlet area of ​​the reaction device to the first pipeline mixer to mix with sodium hydroxide, the pH of the wastewater is adjusted, and the first mixed liquid obtained by the first pipeline mixer is supplied to the water ejector to mix with the inhaled carbon dioxide. In this process, the carbon dioxide dissolves in the water to form carbonic acid and reacts with the calcium ions in the wastewater to form calcium carbonate precipitation. Then the second mixed liquid obtained by the water ejector is supplied to the second pipeline mixer to mix with the flocculant to make them fully contact, and the second mixed liquid is sprayed to the reaction zone of the reaction device through the perforated water pipe to form stirring to make it undergo flocculation reaction, and then the flocculated wastewater is supplied to the sedimentation zone of the sedimentation device for sedimentation separation. Compared with the traditional method of adding carbon dioxide to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration pipe to pressurize the air through a fan, the present application uses a circulating pump to fully mix and contact the wastewater and carbon dioxide in the water ejector, so that the wastewater and carbon dioxide fully react, and then the third mixed liquid is supplied to the reaction zone through the perforated water pipe, avoiding the problem that most of the carbon dioxide diffuses into the air and causes low carbon dioxide utilization rate in the traditional method of supplying carbon dioxide through a perforated aeration pipe. At the same time, the present application does not need to set up a stirring device separately. Therefore, the use of this system can significantly improve the utilization rate of carbon dioxide and reduce equipment costs on the basis of improving the softening effect of wastewater.

[0013] In addition, the system for softening wastewater according to the above embodiment of the present invention may also have the following additional technical features:

[0014] In some embodiments of the present invention, the perforated water distribution pipe includes: a main water distribution pipe, which is arranged below the reaction device in the horizontal direction and is connected to the third mixed liquid outlet; a branch water distribution pipe, which is arranged at intervals in a direction perpendicular to the main water distribution pipe and is connected to the main water distribution pipe, and the branch water distribution pipe extends from the bottom of the reaction device to the reaction zone, and each branch water distribution pipe is arranged with multiple layers of openings along its height direction, and the adjacent two layers of openings are staggered. In this way, the flocculation reaction can be improved while reducing the equipment cost.

[0015] In some embodiments of the present invention, the lowest opening on the branch water distribution pipe is not less than 300 mm above the bottom of the reaction zone.

[0016] In some embodiments of the present invention, the cross-sectional area of ​​the sludge settling zone gradually decreases from top to bottom, thereby enabling the sludge obtained by sedimentation to be discharged smoothly.

[0017] In some embodiments of the present invention, the above-mentioned system for softening wastewater further comprises: a first automatic regulating valve, which is arranged at the inlet of the sodium hydroxide solution; a first pH detector, which is arranged at the outlet of the first mixed solution, and the first pH detector is connected to the first automatic regulating valve, and the first automatic regulating valve adjusts the flow rate of the sodium hydroxide solution based on the display of the first pH detector. In this way, not only can the automatic adjustment of the supply amount of the sodium hydroxide solution be achieved, but also the utilization rate of carbon dioxide can be improved.

[0018] In some embodiments of the present invention, the above-mentioned system for softening wastewater further comprises: a second automatic regulating valve, which is arranged at the carbon dioxide inlet; a second pH detector, which is arranged in the water supply area and connected to the second automatic regulating valve, and the second automatic regulating valve adjusts the flow of carbon dioxide based on the display of the second pH detector. In this way, not only can the automatic regulation of the carbon dioxide supply be achieved, but also the utilization rate of carbon dioxide can be improved.

[0019] In some embodiments of the present invention, the internal circulation pump is connected to the water inlet area via a water suction tray, thereby improving the wastewater softening effect.

[0020] In another aspect of the present invention, the present invention provides a method for softening wastewater. According to an embodiment of the present invention, the method comprises:

[0021] (1) supplying wastewater to the water inlet area, using the internal circulation pump to supply the wastewater from the water inlet area to the first pipeline mixer to mix with the sodium hydroxide solution, supplying the obtained first mixed solution to the water ejector to mix with the inhaled carbon dioxide, and then supplying the obtained second mixed solution to the second pipeline mixer to mix with the flocculant, and supplying the obtained third mixed solution to the perforated water distribution pipe to perform flocculation reaction in the reaction area;

[0022] (2) The flocculated wastewater obtained in the reaction zone of step (1) is supplied to the sedimentation device for sedimentation reaction to obtain sludge and clean water.

[0023] According to the method for softening wastewater of an embodiment of the present invention, a circulating pump is used to supply the wastewater supplied to the water inlet area of ​​the reaction device to the first pipeline mixer to mix with sodium hydroxide, the pH of the wastewater is adjusted, and the first mixed liquid obtained by the first pipeline mixer is supplied to the water ejector to mix with the inhaled carbon dioxide. In this process, the carbon dioxide dissolves in the water to form carbonic acid and reacts with the calcium ions in the wastewater to form calcium carbonate precipitation. Then the second mixed liquid obtained by the water ejector is supplied to the second pipeline mixer to mix with the flocculant to make them fully contact, and the second mixed liquid is sprayed to the reaction zone of the reaction device through the perforated water pipe to form stirring to make it undergo flocculation reaction, and then the flocculated wastewater is supplied to the sedimentation zone of the sedimentation device for sedimentation separation. Compared with the traditional method of adding carbon dioxide to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration pipe to pressurize the air through a fan, the present application uses a circulating pump to fully mix and contact the wastewater and carbon dioxide in the water ejector, so that the wastewater and carbon dioxide fully react, and then the third mixed liquid is supplied to the reaction zone through the perforated water pipe, avoiding the problem that most of the carbon dioxide diffuses into the air and causes low carbon dioxide utilization rate in the traditional method of supplying carbon dioxide through a perforated aeration pipe. At the same time, the present application does not need to set up a stirring device separately. Therefore, the use of this method can significantly improve the utilization rate of carbon dioxide and reduce equipment costs on the basis of improving the softening effect of wastewater.

[0024] In some embodiments of the present invention, the pH of the first mixed solution is 10.5-11.

[0025] In some embodiments of the present invention, the pH value of the wastewater in the water supply area is 8.5-9.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0028] Figure 1 is a schematic diagram of the system structure for softening wastewater according to an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of a perforated water distribution pipe structure in a system for softening wastewater according to another embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the system structure for softening wastewater according to another embodiment of the present invention;

[0031] Figure 4Schematic diagram of the system structure for softening wastewater according to another embodiment of the present invention. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] In one aspect of the present invention, the present invention provides a system for softening wastewater. Figure 1 The system includes: a reaction device 100, an internal circulation pump 200, a first pipeline mixer 300, a water ejector 400, a second pipeline mixer 500 and a sedimentation device 600.

[0038] According to an embodiment of the present invention, referring to Figure 1 A first partition 11 is provided in the reaction device 100, and the first partition 11 divides the reaction device 100 into a water inlet area 12 and a reaction area 13 in the horizontal direction. The lower part of the water inlet area 12 is connected to the lower part of the reaction area 13, and the water inlet area 12 is provided with a wastewater inlet 101, and the reaction area 13 is provided with a perforated water distribution pipe 14. Specifically, the reaction device 100 can be a water tank with a water storage function made of any material. The first partition 11 is arranged in the reaction device 100 along the vertical direction and the lower end of the first partition 11 is at a distance from the bottom of the reaction device 100, thereby dividing the reaction device 100 into a water inlet area 12 and a reaction area 13 which are horizontally distributed and connected at the bottom. The "wastewater" in this application can be any aqueous solution in the field that needs to remove calcium ions, and the perforated water pipe 14 is arranged at the bottom of the reaction zone 13, that is, the wastewater containing flocculant and calcium carbonate after mixing by the second pipeline mixer 500 is sprayed to the reaction zone 13 through the perforated water pipe 14, forming agitation in the reaction zone 13, without the need to set up a separate stirring device, thereby reducing equipment costs.

[0039] According to a specific embodiment of the present invention, referring to Figure 2The perforated water distribution pipe 14 may include a main water distribution pipe 141 and a branch water distribution pipe 142, wherein the main water distribution pipe 141 is arranged below the reaction device 100 in the horizontal direction, and the branch water distribution pipe 142 is arranged at intervals in the direction vertical to the main water distribution pipe 141 and is connected to the main water distribution pipe 141, and the branch water distribution pipe 142 extends from the bottom of the reaction device 100 to the reaction zone 13, and each branch water distribution pipe 142 is arranged with multiple layers of openings 143 along its height direction, and two adjacent layers of openings 143 are staggered. Specifically, the wastewater containing flocculant and calcium carbonate mixed by the second pipeline mixer 500 is supplied to the main water distribution pipe 141, and then supplied to the branch water distribution pipe 142 through the main water distribution pipe 141, and sprayed to the reaction zone 13 through the openings 143 on the branch water distribution pipe 142. Moreover, since multiple layers of openings 143 are arranged at intervals along the length direction of each branch water distribution pipe 142, and adjacent openings 143 are staggered, the wastewater sprayed through the openings 143 arranged on different layers can be stirred in the reaction zone 13. Furthermore, the lowest opening 143 on the branch water distribution pipe 142 is not less than 300 mm above the bottom of the reaction zone 13, that is, the lowest opening 143 on the branch water distribution pipe 142 needs to be above the reaction zone 13 to ensure that the wastewater sprayed through the openings 142 on the branch water distribution pipe 142 is supplied to the reaction zone 13.

[0040] According to an embodiment of the present invention, referring to Figure 1 , the inner circulation pump 200 is connected to the water inlet area 12. Preferably, the inner circulation pump 200 is connected to the water inlet area 12 through the water absorption tray 21, so that the wastewater supplied to the water inlet area 12 is supplied to the subsequent process in time, and a large amount of wastewater is prevented from being retained in the water inlet area 12 and affecting the removal of calcium ions in the wastewater in the reaction area 13. It should be noted that the inner circulation pump 200 can be any device that can provide power in the prior art, and the water absorption tray 21 can be any receiving device with a large contact area, for example, it can be a disc-shaped receiving device with an open upper end and a cavity, that is, the wastewater supplied to the water inlet area 12 through the wastewater inlet 101 enters its cavity through the upper end opening of the water absorption tray 21, and then is extracted through the water outlet provided at the bottom of the water absorption tray 21 through the inner circulation pump and supplied to the subsequent process. Further, the location of the water absorption tray 21 is not particularly limited, as long as it can achieve the maximum acceptance of the wastewater supplied to the water inlet area 12 through the wastewater inlet 101.

[0041] According to an embodiment of the present invention, referring to Figure 1The first pipeline mixer 300 has a sodium hydroxide solution inlet 301, a wastewater inlet 302 and a first mixed liquid outlet 303. The wastewater inlet 301 is connected to the internal circulation pump 200, and is suitable for using the internal circulation pump 200 to supply the wastewater supplied to the water inlet area 12 to the first pipeline mixer 300 through the wastewater inlet 301 to mix with sodium hydroxide, thereby adjusting the pH of the wastewater to 10.5-11 to obtain a first mixed liquid. It should be noted that the first pipeline mixer can be any device that can achieve a mixing function in the prior art, preferably a device that can achieve turbulent mixing, that is, increase the turbulence intensity of the wastewater and the sodium hydroxide solution therein so that the two are fully mixed. Further, refer to Figure 3 A first automatic regulating valve 31 is arranged at the sodium hydroxide solution inlet 301, and a first pH detector 32 is arranged at the first mixed liquid outlet 303, and the first pH detector 32 is connected to the first automatic regulating valve 31, and based on the display of the first pH detector 32, the first automatic regulating valve 31 adjusts the flow rate of the sodium hydroxide solution, that is, the first pH detector 32 is used to detect the pH of the first mixed liquid in real time. If the pH measurement value of the first mixed liquid is higher than 10.5-11, it is fed back to the first automatic regulating valve 31 to reduce the opening and reduce the sodium hydroxide supply. On the contrary, if the pH measurement value of the first mixed liquid is lower than 10.5-11, it is fed back to the first automatic regulating valve 31 to increase the opening and increase the sodium hydroxide supply.

[0042] According to an embodiment of the present invention, referring to Figure 1 The water ejector 400 has a carbon dioxide inlet 401, a first mixed liquid inlet 402 and a second mixed liquid outlet 403. The first mixed liquid inlet 401 is connected to the first mixed liquid outlet 303 and is suitable for supplying the first mixed liquid obtained in the first pipeline mixer 300 to the water ejector 400 to form a negative pressure to absorb carbon dioxide through the carbon dioxide inlet 401, so that carbon dioxide is dissolved in water and reacts with calcium ions in the wastewater to form calcium carbonate precipitates. Compared with the traditional method of adding carbon dioxide to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration tube with a fan pressurization, the present application fully mixes and contacts the wastewater with carbon dioxide in the water ejector first, so that the wastewater and carbon dioxide fully react, avoiding the problem that the traditional method of supplying carbon dioxide through a perforated aeration tube causes most of the carbon dioxide to diffuse into the air, resulting in a low carbon dioxide utilization rate. Specifically, the amount of carbon dioxide absorbed is based on maintaining the pH of the flocculated wastewater overflowing from the reaction zone to the water supply zone at 8.5-9.

[0043] According to an embodiment of the present invention, referring to Figure 1The second pipeline mixer 500 has a flocculant inlet 501, a second mixed liquid inlet 502 and a third mixed liquid outlet 503. The second mixed liquid inlet 502 is connected to the second mixed liquid outlet 403, and the third mixed liquid outlet 503 is connected to the perforated water distribution pipe 14, and is suitable for supplying the second mixed liquid obtained in the above-mentioned water ejector 400 to the second pipeline mixer 500 to mix with the flocculant supplied therein, and then injecting the obtained third mixed liquid to the reaction zone 13 through the perforated water distribution pipe 14 to form stirring and flocculation reaction. Specifically, the third mixed liquid outlet 503 is connected to the main water distribution pipe 141 on the perforated water distribution pipe 14. It should be noted that the flocculant can be any agent that can achieve flocculation in the prior art, such as polyacrylamide, and the second pipeline mixer can be any device that can achieve a mixing function in the prior art, preferably a device that can achieve turbulent mixing, that is, to increase the turbulence intensity of the second mixed liquid and the flocculant therein so that the two are fully mixed.

[0044] According to an embodiment of the present invention, referring to Figure 1 A separation zone 61 and a mud settling zone 62 are defined in the sedimentation device 600 along its height direction. The separation zone 61 is provided with a second partition plate 63. The second partition plate 63 divides the separation zone 61 into a water supply zone 611 and a sedimentation zone 612 in the horizontal direction. The water supply zone 611 is connected to the reaction zone 13. The sedimentation zone 612 is provided with an inclined plate filler 64. An overflow port 601 is provided at the top of the sedimentation zone 612. A mud discharge port 602 is provided at the bottom of the mud settling zone 62. Specifically, the filler in the inclined plate filler can be any material with sedimentation separation in the prior art, such as PVC particles, PP particles, etc. The second partition 63 is vertically arranged in the separation zone 61 along the vertical direction. The flocculated wastewater obtained in the reaction zone 13 overflows into the water supply zone 611, and then enters the sludge zone 62. At the same time, it overflows into the sedimentation zone 612 for sedimentation separation through the inclined plate filler. The separated clean water is discharged through the overflow port 601 at the top of the sedimentation zone 612, and the sludge obtained by sedimentation is discharged through the sludge discharge port 602 at the bottom of the sedimentation zone 62. Preferably, along the direction from top to bottom, the cross-sectional area of ​​the sludge zone 62 gradually decreases, that is, the sludge zone 62 is a conical structure. In this way, the sludge obtained by sedimentation can be discharged smoothly.

[0045] For further reference, Figure 4A second automatic regulating valve 65 is provided at the carbon dioxide inlet 401, a second pH detector 66 is arranged in the water supply area 611, and the second pH detector 66 is connected to the second automatic regulating valve 65. Based on the display of the second pH detector 66, the second automatic regulating valve 65 adjusts the flow of carbon dioxide. That is, the second pH detector 66 is used to detect the pH of the flocculated wastewater overflowing from the reaction area to the water supply area in real time. If the pH measurement value of the flocculated wastewater is higher than 8.5-9, it is fed back to the second automatic regulating valve 65 to increase the opening and increase the carbon dioxide supply. On the contrary, if the pH measurement value of the flocculated wastewater is lower than 8.5-9, it is fed back to the second automatic regulating valve 65 to reduce the opening and reduce the carbon dioxide supply. In this way, not only the automatic adjustment of the carbon dioxide supply can be achieved, but also the utilization rate of carbon dioxide can be improved.

[0046] According to the system for softening wastewater of an embodiment of the present invention, a circulating pump is used to supply the wastewater supplied to the water inlet area of ​​the reaction device to the first pipeline mixer to be mixed with sodium hydroxide, the pH of the wastewater is adjusted, and the first mixed liquid obtained by the first pipeline mixer is supplied to the water ejector to be mixed with the inhaled carbon dioxide. In this process, the carbon dioxide dissolves in the water to form carbonic acid and reacts with the calcium ions in the wastewater to form calcium carbonate precipitation. Then the second mixed liquid obtained by the water ejector is supplied to the second pipeline mixer to be mixed with the flocculant to make them fully contact, and the second mixed liquid is sprayed to the reaction zone of the reaction device through the perforated water pipe to form stirring to make it undergo flocculation reaction, and then the flocculated wastewater is supplied to the inclined plate filler in the sedimentation zone of the sedimentation device for sedimentation separation. Compared with the traditional method of adding carbon dioxide to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration pipe to pressurize the air through a fan, the present application uses a circulating pump to fully mix and contact the wastewater and carbon dioxide in the water ejector, so that the wastewater and carbon dioxide fully react, and then the third mixed liquid is supplied to the reaction zone through the perforated water pipe, avoiding the problem that most of the carbon dioxide diffuses into the air and causes low carbon dioxide utilization rate in the traditional method of supplying carbon dioxide through a perforated aeration pipe. At the same time, the present application does not need to set up a stirring device separately. Therefore, the use of this system can significantly improve the utilization rate of carbon dioxide and reduce equipment costs on the basis of improving the softening effect of wastewater.

[0047] The system for softening wastewater of the present application also has one of the following advantages:

[0048] (1) The carbon dioxide is sucked in by a water ejector and a water pump to fully mix with the wastewater for reaction. Compared with the traditional method, the utilization rate of carbon dioxide is higher and the pressure requirement of the carbon dioxide gas source is reduced;

[0049] (2) Using a pipeline mixer and water pump to add sodium hydroxide, flocculants and other reagents, so that the reagents can quickly mix and react with the wastewater, which can save equipment such as pH adjustment tanks and flocculation tanks;

[0050] (3) The use of hydraulic circulation and the use of perforated water pipes to produce a stirring effect can eliminate the need for mechanical mixers, reducing investment and energy consumption.

[0051] (4) The system uses integrated equipment with its own control unit to realize process automation.

[0052] In another aspect of the present invention, the present invention discloses a method for softening wastewater using the above-mentioned system for softening wastewater. According to an embodiment of the present invention, the method comprises:

[0053] S100: Supply wastewater to the water inlet area, use an internal circulation pump to supply the wastewater from the water inlet area to the first pipeline mixer to mix with the sodium hydroxide solution, supply the obtained first mixed solution to the water ejector to mix with the inhaled carbon dioxide, then supply the obtained second mixed solution to the second pipeline mixer to mix with the flocculant, and supply the obtained third mixed solution to the perforated water distribution pipe to perform flocculation reaction in the reaction area

[0054] In this step, the "wastewater" of the present application can be any aqueous solution in the art that needs to remove calcium ions. The wastewater is supplied to the water inlet through the wastewater inlet, and then the wastewater is supplied to the first pipeline mixer by an internal circulation pump to mix with sodium hydroxide, and the pH of the wastewater is adjusted to 10.5-11 to obtain a first mixed solution. Then the first mixed solution obtained in the first pipeline mixer is supplied to the water ejector to form a negative pressure to absorb carbon dioxide through the carbon dioxide inlet, so that carbon dioxide is dissolved in water and reacts with calcium ions in the wastewater to form calcium carbonate precipitates. Compared with the traditional carbon dioxide using the pressure of the gas source itself or through the perforated aeration tube pressurized by a fan to add to the softening reaction tank, the present application fully mixes and contacts the wastewater and carbon dioxide in the water ejector first, so that the wastewater and carbon dioxide fully react, avoiding the problem that most of the carbon dioxide is diffused into the air and the utilization rate of carbon dioxide is low due to the traditional perforated aeration tube supplying carbon dioxide. The amount of carbon dioxide absorbed is based on maintaining the pH of the flocculated wastewater overflowing from the reaction zone to the water supply zone at 8.5-9. Then the second mixed liquid obtained in the above-mentioned water ejector is supplied to the second pipeline mixer to be mixed with the flocculant supplied therein, and then the obtained third mixed liquid is sprayed to the reaction zone through the perforated water pipe to form stirring and flocculation reaction.

[0055] S200: The flocculated wastewater obtained in the reaction zone of step S100 is supplied to a sedimentation device for sedimentation reaction.

[0056] In this step, the flocculated wastewater obtained in the reaction zone overflows into the water supply zone, and then enters the sludge settling zone for sedimentation. At the same time, the overflow enters the sedimentation zone for sedimentation separation through the inclined plate filler. The separated clean water is discharged through the overflow port at the top of the sedimentation zone, and the sludge obtained by sedimentation is discharged through the sludge discharge port at the bottom of the sedimentation zone. In this way, the sludge obtained by sedimentation can be discharged smoothly.

[0057] According to the method for softening wastewater of an embodiment of the present invention, a circulating pump is used to supply the wastewater supplied to the water inlet area of ​​the reaction device to the first pipeline mixer to mix with sodium hydroxide, the pH of the wastewater is adjusted, and the first mixed liquid obtained by the first pipeline mixer is supplied to the water ejector to mix with the inhaled carbon dioxide. In this process, the carbon dioxide dissolves in the water to form carbonic acid and reacts with the calcium ions in the wastewater to form calcium carbonate precipitation. Then the second mixed liquid obtained by the water ejector is supplied to the second pipeline mixer to mix with the flocculant to make them fully contact, and the second mixed liquid is sprayed to the reaction zone of the reaction device through the perforated water pipe to form stirring to make it undergo flocculation reaction, and then the flocculated wastewater is supplied to the inclined plate filler in the sedimentation zone of the sedimentation device for sedimentation separation. Compared with the traditional method of adding carbon dioxide to the softening reaction tank by using the pressure of the gas source itself or by using a perforated aeration pipe to pressurize the air through a fan, the present application uses a circulating pump to fully mix and contact the wastewater and carbon dioxide in the water ejector, so that the wastewater and carbon dioxide fully react, and then the third mixed liquid is supplied to the reaction zone through the perforated water pipe, avoiding the problem that most of the carbon dioxide diffuses into the air and causes low carbon dioxide utilization rate in the traditional method of supplying carbon dioxide through a perforated aeration pipe. At the same time, the present application does not need to set up a stirring device separately. Therefore, the use of this method can significantly improve the utilization rate of carbon dioxide and reduce equipment costs on the basis of improving the softening effect of wastewater.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A system for softening wastewater, characterized in that: include: A reaction device, wherein a first partition is provided in the reaction device, wherein the first partition divides the reaction device into a water inlet zone and a reaction zone in a horizontal direction, wherein the lower part of the water inlet zone is connected to the lower part of the reaction zone, and the water inlet zone is provided with a wastewater inlet, and the reaction zone is provided with a perforated water distribution pipe; An internal circulation pump, wherein the internal circulation pump is connected to the water inlet area; A first pipeline mixer, wherein the first pipeline mixer has a sodium hydroxide solution inlet, a wastewater inlet and a first mixed solution outlet, and the wastewater inlet is connected to the internal circulation pump; A water ejector, wherein the water ejector has a carbon dioxide inlet, a first mixed liquid inlet, and a second mixed liquid outlet, wherein the first mixed liquid inlet is connected to the first mixed liquid outlet; a second pipeline mixer, the second pipeline mixer having a flocculant inlet, a second mixed liquid inlet and a third mixed liquid outlet, the second mixed liquid inlet is connected to the second mixed liquid outlet, and the third mixed liquid outlet is connected to the perforated water distribution pipe; A settling device, wherein a separation zone and a mud settling zone are defined in the settling device along its height direction, the separation zone is provided with a second partition, the second partition separates the separation zone into a water supply zone and a settling zone in the horizontal direction, the water supply zone is connected to the reaction zone, the settling zone is provided with an inclined plate filler, the top of the settling zone is provided with an overflow port, and the bottom of the mud settling zone is provided with a mud discharge port, The perforated water pipe comprises: A main water distribution pipe, which is arranged below the reaction device in a horizontal direction and is connected to the third mixed liquid outlet; Branch water distribution pipes are arranged at intervals in a direction perpendicular to the main water distribution pipe and are connected to the main water distribution pipe. The branch water distribution pipes extend from the bottom of the reaction device and extend to the reaction zone. Each branch water distribution pipe is arranged with multiple layers of openings along its height direction, and two adjacent layers of openings are staggered.

2. The system according to claim 1, characterized in that The lowest opening on the branch water distribution pipe is not less than 300 mm above the bottom of the reaction zone.

3. The system according to claim 1, characterized in that Along the direction from top to bottom, the cross-sectional area of ​​the siltation zone gradually decreases.

4. The system according to claim 1, characterized in that Further including: a first automatic regulating valve, the first automatic regulating valve being arranged at the inlet of the sodium hydroxide solution; A first pH detector is provided at the outlet of the first mixed solution, and the first pH detector is connected to the first automatic regulating valve. Based on the display of the first pH detector, the first automatic regulating valve adjusts the flow rate of the sodium hydroxide solution.

5. The system according to claim 1, characterized in that Further including: a second automatic regulating valve, the second automatic regulating valve being arranged at the carbon dioxide inlet; A second pH detector is provided in the water supply area, and the second pH detector is connected to the second automatic regulating valve. Based on the display of the second pH detector, the second automatic regulating valve adjusts the flow of carbon dioxide.

6. The system according to claim 1, characterized in that The internal circulation pump is connected to the water inlet area through a water suction tray.

7. A method for softening wastewater using the system according to any one of claims 1 to 6, characterized in that: include: (1) supplying wastewater to the water inlet area, using the internal circulation pump to supply the wastewater from the water inlet area to the first pipeline mixer to mix with the sodium hydroxide solution, supplying the obtained first mixed solution to the water ejector to mix with the inhaled carbon dioxide, and then supplying the obtained second mixed solution to the second pipeline mixer to mix with the flocculant, and supplying the obtained third mixed solution to the perforated water distribution pipe to perform flocculation reaction in the reaction area; (2) The flocculated wastewater obtained in the reaction zone of step (1) is supplied to the sedimentation device for sedimentation reaction to obtain sludge and clean water.

8. The method according to claim 7, characterized in that The pH of the first mixed solution is 10.5-11.

9. The method according to claim 7, characterized in that: The pH value of wastewater in the water supply area is 8.5-9.

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