System and method for removing hardness of wastewater and capturing carbon dioxide through supergravity

Abstract

The invention provides a system and a method for removing hardness of wastewater and capturing carbon dioxide through supergravity. The system comprises a wastewater mixing tank and a supergravity reactor. The waste water mixing tank is connected with a waste water source, waste water in the waste water source contains metal ions and has first hardness, and the waste water mixing tank is used for mixing the waste water and alkaline liquid so as to adjust the pH value of the waste water to be alkaline and form mixed waste water. The supergravity reactor is connected with the waste water mixing tank, gas with first carbon dioxide concentration is introduced into the supergravity reactor, the supergravity reactor mixes the mixed waste water and the gas according to the flow ratio of the gas to the mixed waste water being (30-400): 1 for reaction, and metal salt precipitates, alkaline recovery liquid and treated gas are generated.

Description

Technical Field

[0001] The present invention relates to a system and method for removing hardness in wastewater and capturing carbon dioxide, and in particular to a system and method for reducing hardness in wastewater, removing carbon dioxide in waste gas, and generating metal precipitates with economic value. Background Art

[0002] A large amount of wastewater is often generated during industrial production. The wastewater contains high concentrations of metal compounds and has a high water hardness. It is easy to form scale, clog pipelines and damage equipment, making subsequent treatment difficult.

[0003] The existing methods for reducing the hardness of wastewater are distillation, lime soda method and cation exchange method. 2+ and Mg 2+ The boiling points of ions are different. The temperature is raised to convert water into water vapor, leaving solid (scale), and then the water vapor is condensed back into water to complete the recovery. The lime soda method is to convert calcium oxide CaO (quicklime) and sodium carbonate Na 2 CO 3 (soda) is added to water, allowing the sodium ions to convert Ca 2+ and Mg 2+ After ion exchange, calcium carbonate or magnesium carbonate precipitate is obtained, achieving the purpose of reducing the hardness of the water, but the disadvantage of this method is that sodium ions still remain in the water; the cation exchange method uses ion exchange resin, adds sodium chloride or sodium carbonate and other sodium-containing compounds to the resin, and exchanges the hardness mineral ions in the water into sodium ions and flows out. The hardness mineral ions will be adsorbed by the resin or scaled on the resin. When the hard water flows around the beads, the hardness mineral ions are absorbed first and replace the sodium ions.

[0004] Although the above three methods can effectively reduce the hardness of water and obtain by-products in different ways, the by-products of the distillation method have no recycling value. In addition, in addition to adjusting the pH, the above three methods also require additional chemicals to achieve the purpose of removing hardness, which increases the cost of the removal process. In addition, although the lime soda method and the cation exchange method will produce calcium carbonate and magnesium with recycling value, they need to be further purified to reach a recyclable purity, and the cation exchange method requires regular cleaning of the resin to ensure the exchange capacity of the resin. Summary of the invention

[0005] To this end, the object of the present invention is to provide a method for reducing the hardness in wastewater and removing waste gas at the same time, which can overcome the shortcomings of the above-mentioned prior art.

[0006] The present invention provides a system for removing wastewater hardness and capturing carbon dioxide by ultra-gravity, comprising:

[0007] a wastewater mixing tank connected to a wastewater source, wherein the wastewater in the wastewater source contains metal ions and has a first hardness, and the wastewater mixing tank is used to mix the wastewater with an alkaline liquid to adjust the pH value of the wastewater to alkaline and form mixed wastewater; and

[0008] A supergravity reactor is connected to the wastewater mixing tank and introduced with a gas having a first carbon dioxide concentration, wherein the supergravity reactor mixes the mixed wastewater and the gas at a flow rate ratio of the gas to the mixed wastewater of 30 to 400:1 to react and generate a metal salt precipitate, an alkaline recovery liquid and a treated gas;

[0009] The alkaline recovery liquid has a second hardness that is lower than the first hardness, and the treated gas has a second carbon dioxide concentration that is lower than the first carbon dioxide concentration.

[0010] Preferably, the system further comprises: a recovery temporary storage tank, which is respectively connected to the supergravity reactor and the wastewater mixing tank, and is used to inject the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles.

[0011] Preferably, the system further comprises: a blower connected to the supergravity reactor to pass the gas containing the first carbon dioxide concentration into the supergravity reactor.

[0012] Preferably, the wastewater contains calcium chloride.

[0013] Preferably, the gas is exhaust gas or air, and the first carbon dioxide concentration of the gas is 0.2-12%.

[0014] Preferably, the alkaline liquid is alkaline wastewater, sodium hydroxide or potassium hydroxide.

[0015] Preferably, the supergravity factor of the supergravity reactor is 50-250.

[0016] Preferably, the system has a carbon dioxide removal rate of 5.5-64% and / or a hardness removal rate of 8-99%.

[0017] The present invention also provides a system for removing wastewater hardness and capturing carbon dioxide by ultra-gravity, comprising:

[0018] a wastewater mixing tank connected to a wastewater source, wherein the wastewater in the wastewater source contains metal ions and has a first hardness of 700 to 4100 ppm, and the wastewater mixing tank is used to mix the wastewater with an alkaline liquid to adjust the pH value of the wastewater to 11.5 to 12.5 and form mixed wastewater; and

[0019] A supergravity reactor is connected to the wastewater mixing tank and introduced with a gas having a first carbon dioxide concentration of 0.2 to 12%. The supergravity reactor mixes the mixed wastewater and the gas at a flow ratio of 30 to 400:1 and a supergravity factor of 50 to 250 to react and generate a metal salt precipitate, an alkaline recovery liquid and a treated gas;

[0020] A temporary recovery tank connected to the supergravity reactor and / or the wastewater mixing tank, used to contain the alkaline recovery liquid or inject the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles of 2 to 17 times;

[0021] The alkaline recovery liquid has a second hardness, which is lower than the first hardness, the treated gas has a second carbon dioxide concentration, which is lower than the first carbon dioxide concentration, and the carbon dioxide removal rate of the system is 5.5-64% and the hardness removal rate is 8-99%.

[0022] In addition, the present invention provides a method for removing wastewater hardness and capturing carbon dioxide by ultra-gravity, which comprises the following steps:

[0023] injecting wastewater from a wastewater source into a wastewater mixing tank, the wastewater containing metal ions and having a first hardness, mixing the wastewater with an alkaline liquid in the wastewater mixing tank to adjust the pH value of the wastewater to alkaline, and forming mixed wastewater; and

[0024] The mixed wastewater is injected into a supergravity reactor, and a gas having a first carbon dioxide concentration is introduced, wherein the supergravity reactor mixes the mixed wastewater and the gas at a flow rate ratio of 30 to 400:1 to react and generate a metal salt precipitate, an alkaline recovery liquid and a treated gas;

[0025] The alkaline recovery liquid has a second hardness that is lower than the first hardness, and the treated gas has a second carbon dioxide concentration that is lower than the first carbon dioxide concentration.

[0026] Preferably, the method further comprises: injecting the alkaline recovery liquid into a recovery temporary storage tank, and injecting the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles.

[0027] The present invention also provides a method for removing wastewater hardness and capturing carbon dioxide by ultra-gravity, which comprises the following steps:

[0028] Injecting wastewater from a wastewater source into a wastewater mixing tank, the wastewater containing metal ions and having a first hardness of 700 to 4100 ppm, mixing the wastewater with an alkaline liquid in the wastewater mixing tank to adjust the pH value of the wastewater to 11.5 to 12.5, and forming mixed wastewater;

[0029] The mixed wastewater is injected into a supergravity reactor, and a gas having a first carbon dioxide concentration of 0.2 to 12% is introduced, wherein the supergravity reactor mixes the mixed wastewater and the gas at a flow ratio of the gas to the mixed wastewater of 30 to 400:1 and a supergravity factor of 50 to 250 to react to generate a metal salt precipitate, an alkaline recovery liquid and a treated gas; and

[0030] The alkaline recovery liquid is injected into a temporary recovery tank, which is connected to the supergravity reactor and / or the wastewater mixing tank to accommodate the alkaline recovery liquid or inject the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles of 2 to 17 times;

[0031] The alkaline recovery liquid has a second hardness, which is lower than the first hardness, the treated gas has a second carbon dioxide concentration, which is lower than the first carbon dioxide concentration, and the carbon dioxide removal rate of the method is 5.5-64% and the hardness removal rate is 8-99%.

[0032] The system and method for removing hardness from wastewater of the present invention can reduce hardness in wastewater, remove carbon dioxide from waste gas, and generate metal salt precipitates with economic value, by (1) adjusting the pH of wastewater, (2) simultaneously passing the hardness and carbon dioxide in wastewater into a reactor to improve mass transfer efficiency, (3) collecting precipitated solids for analysis to determine their composition, and (4) adjusting the two system modes to meet the needs. Therefore, the system and method of the present invention only need to adjust the pH throughout the process, and the reactants are all from gas phase and water phase wastes, which are treated with waste and recycled into industrial raw materials for reuse, such as calcium carbonate, and the purity is more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of the first embodiment of the method for removing wastewater hardness and capturing carbon dioxide by ultra-gravity according to the present invention.

[0034] Figure 2 It is a flow chart of a second embodiment of the method for removing hardness from wastewater and capturing carbon dioxide by ultra-gravity according to the present invention.

[0035] Figure 3 It is a comparison chart of the method of the present invention for removing wastewater hardness and capturing carbon dioxide under different hypergravity factors.

[0036] Figure 4 Schematic diagram of a first embodiment of the system for removing wastewater hardness and capturing carbon dioxide using ultra-gravity technology according to the present invention.

[0037] Figure 5 Schematic diagram of a second embodiment of the system for removing wastewater hardness and capturing carbon dioxide using ultra-gravity technology according to the present invention.

[0038] Figure 6 It is a comparison diagram of the method and system of the present invention for removing wastewater hardness by ultra-gravity and capturing carbon dioxide using different alkaline liquids.

[0039] Reference numerals:

[0040] 1. A continuous flow system for removing hardness from wastewater by ultra-gravity and capturing carbon dioxide; 2. A circulating flow system for removing hardness from wastewater by ultra-gravity and capturing carbon dioxide; 10. A wastewater source; 11. A wastewater mixing tank; 111. An alkaline liquid tank; 112. A first pump; 113. A pH measuring device; 114. A second pump; 115. A liquid flow meter; 12. An ultra-gravity reactor; 121. A gas; 122. A gate valve; 123. A fan; 124. A gas flow meter; 125. A treated gas; 13. A recovery storage tank; 131. A third pump; 132. A fourth pump; 14. An alkaline recovery liquid; 15. A metal salt precipitate; S100 to S120, steps; S200 to S230, steps. DETAILED DESCRIPTION

[0041] The present invention will be further described by the following examples, but it should be understood that the examples listed are only used to illustrate the implementation mode of the present invention and are not used to limit the scope of the present invention.

[0042] Please refer to Figures 1 to 4 , which are respectively flow charts of the first embodiment and the second embodiment of the method for removing wastewater hardness and capturing carbon dioxide by ultra-gravity of the present invention.

[0043] The method of removing wastewater hardness and capturing carbon dioxide by ultra-gravity of the present invention comprises two different embodiments. The first embodiment is a continuous flow, such as Figure 1 As shown, it is suitable for when the hardness in the wastewater is low and the concentration of the waste gas used for reaction is high enough. The hardness in the water can be removed through continuous flow operation. The solid and liquid are then separated, the solid is outsourced for recycling, and the liquid is introduced into the subsequent membrane biological reactor (MBR) process.

[0044] The first embodiment of the method of removing wastewater hardness and capturing carbon dioxide by high gravity of the present invention comprises the following steps:

[0045] Step S100: injecting wastewater from a wastewater source into a wastewater mixing tank, wherein the wastewater contains metal ions and has a first hardness, mixing the wastewater with an alkaline liquid in the wastewater mixing tank to adjust the pH value of the wastewater to alkaline, and forming mixed wastewater.

[0046] Step S110: Inject the mixed wastewater into a supergravity reactor, and introduce a gas with a first carbon dioxide concentration. The supergravity reactor mixes the mixed wastewater and the gas at a flow ratio of 30 to 400:1 to react and generate metal salt precipitate, alkaline recovery liquid and treated gas.

[0047] Step S120: Determine the hardness of the alkaline recovery liquid, analyze the composition of the metal salt precipitate, and / or analyze the second carbon dioxide concentration of the treated gas.

[0048] The second embodiment is a circulating flow, such as Figure 2 As shown, it is suitable for when the hardness of the wastewater is low and the concentration of the waste gas used for reaction is relatively low. The required number of cycles can be estimated based on the test results after the first cycle through the operation of the circulating flow, and the pH value needs to be maintained during the cycle. After achieving the target hardness, the solid and liquid are separated, the solid is outsourced for recycling, and the liquid is introduced into the subsequent membrane biological reactor (MBR) process.

[0049] The second embodiment of the method of removing wastewater hardness and capturing carbon dioxide by high gravity of the present invention comprises the following steps:

[0050] Step S200: Inject wastewater from a wastewater source 10 into a wastewater mixing tank 11, wherein the wastewater contains metal ions and has a first hardness, and mix the wastewater with an alkaline liquid in the wastewater mixing tank 11 to adjust the pH value of the wastewater to alkaline and form mixed wastewater.

[0051] Step S210: Inject the mixed wastewater into the supergravity reactor 12, and introduce a gas with a first carbon dioxide concentration. The supergravity reactor 12 mixes the mixed wastewater and the gas at a flow ratio of 30 to 400:1 to react and generate metal salt precipitate, alkaline recovery liquid and treated gas.

[0052] Step S220: Determine a second hardness of the alkaline recovery liquid, analyze the composition of the metal salt precipitate, and / or analyze a second carbon dioxide concentration of the treated gas.

[0053] Step S230: If the second hardness and / or the second carbon dioxide concentration does not reach the expected value, the alkaline recovery liquid is injected into the recovery temporary storage tank 13, and the alkaline recovery liquid is injected into the wastewater mixing tank 11 for a specific number of cycles.

[0054] In steps S100 and S200, the alkaline liquid for adjusting the pH value of the wastewater is sodium hydroxide, potassium hydroxide or alkaline wastewater, and the pH value of the wastewater is adjusted to above 11, preferably 11.5 to 12.5. The amount of alkaline liquid added is determined based on the amount required to adjust the wastewater to a specific pH value, and the amount can be calculated by methods known in the art.

[0055] In steps S110 and S210, wastewater and gas that can produce precipitation are simultaneously introduced into the ultra-gravity reactor 12 for improving mass transfer efficiency. The gas used is waste gas or air with a first carbon dioxide concentration between 0.2% and 12%, and the flow ratio of the gas to the first mixed wastewater is between 30 and 400.

[0056] An example of the high gravity reactor 12 is a high gravity rotating packed bed, and the high gravity factor is set between 50-250.

[0057] Please refer to Figure 3 , which is a comparison diagram of the method for removing wastewater hardness and capturing carbon dioxide by high gravity of the present invention at different high gravity factors, wherein pH = 11.55, the flow rate of the first mixed wastewater (Q L )=0.18L / min, gas flow rate (Q G )=72L / min, the flow rate ratio of gas to the first mixed wastewater (Q G / Q L )=400.

[0058] like Figure 3 As shown in the figure, when the hypergravity factor is 50, the removal efficiency of calcium ions is 25%; when the hypergravity is 89, the removal efficiency of calcium ions is 33%; when the hypergravity is 139, the removal efficiency of calcium ions is 42%. Therefore, the higher the hypergravity factor, the higher the removal efficiency of calcium ions. From this result, it can be seen that it is necessary to increase the hypergravity factor. When enlarging the design, the currently obtained hypergravity factor can be used to compare the speed. The calculation formula of the hypergravity factor is shown in Mathematical Formula 1:

[0059]

[0060] Where, β: supergravity factor (dimensionless), r 1 : Inner diameter of packed bed (m), r 2 : outer diameter of the packed bed (m), ω: rotation speed (rpm), g: acceleration due to gravity (9.8 m / s 2 ).

[0061] In summary, the method for reducing hardness in wastewater of the present invention comprises the following steps:

[0062] (1) Adjust the pH of the wastewater and adjust the liquid environment to an environment that is suitable for gas absorption. Taking carbon dioxide as an example, liquid alkali (sodium hydroxide, NaOH) needs to be added to adjust it to an alkaline environment;

[0063] (2) The wastewater and the gas that can produce precipitation are simultaneously introduced into a reactor for improving mass transfer efficiency to react, so as to recover a precipitate containing metal ions and alkaline recovered water with low hardness, wherein the pH value of the recovered water is greater than 11.

[0064] The present invention not only removes the hardness in wastewater, but also produces precipitates with recycling value and consumes part of the waste gas.

[0065] Please refer to Figure 4 as well as Figure 5 , which are schematic diagrams of the first embodiment and the second embodiment of the system for removing hardness from wastewater and capturing carbon dioxide by ultra-gravity of the present invention, respectively. The system for removing hardness from wastewater and capturing carbon dioxide by ultra-gravity of the present invention comprises two different embodiments, the first embodiment is a continuous flow system 1, which is the first embodiment of the method for removing hardness from wastewater and capturing carbon dioxide by ultra-gravity of the present invention as described above; the second embodiment is a circulating flow system 2, which is the second embodiment of the method for removing hardness from wastewater and capturing carbon dioxide by ultra-gravity of the present invention as described above.

[0066] like Figure 4 as well as Figure 5 As shown, the continuous flow system 1 for removing hardness of wastewater and capturing carbon dioxide by ultra-gravity and the circulating flow system 2 for removing hardness of wastewater and capturing carbon dioxide by ultra-gravity of the present invention include: a wastewater mixing tank 11, a ultra-gravity reactor 12, a recovery temporary storage tank 13, a fan 123, a first pump 112, a second pump 114, a third pump 131 and a fourth pump 132.

[0067] The wastewater mixing tank 11 can be connected to the wastewater source 10 and the alkaline liquid tank 111 by pipelines, respectively. The wastewater mixing tank 11 receives wastewater containing metal ions and having a first hardness from the wastewater source 10. The alkaline liquid tank 111 injects alkaline liquid into the wastewater mixing tank 11 through a first pump 112. The alkaline liquid is alkaline wastewater, sodium hydroxide or potassium hydroxide. The wastewater mixing tank 11 is provided with a stirring component to mix the wastewater and the alkaline liquid to form mixed wastewater.

[0068] In addition, the pH value of the mixed wastewater in the wastewater mixing tank 11 can be measured by the pH measuring device 113 and adjusted to alkaline, that is, the pH value is above 11, preferably 11.5-12.5. Examples of the pH measuring device 113 are a pH meter, a pH meter, a pH detector or a pH monitor, etc. The pH measuring device 113 can measure the pH value and / or calculate the required amount of alkaline liquid according to the pH value and the type of alkaline liquid, so that the alkaline liquid tank 111 adds an appropriate amount of alkaline liquid.

[0069] The wastewater mixing tank 11 is connected to the supergravity reactor 12 by a pipeline. The wastewater mixing tank 11 can inject the alkaline mixed wastewater into the supergravity reactor 12 through the second pump 114, and the flow rate (Q) of the mixed wastewater is measured by the liquid flow meter 115. L ).

[0070] The example of the high gravity reactor 12 is a high gravity rotating packed bed, and is provided with an air inlet and an exhaust port. A gas 121 having a first carbon dioxide concentration can be introduced through a gate valve 122 by a blower 123, and a flow rate (Q) of the gas 121 can be measured by a gas flow meter 124. G ), the gas is exhaust gas or air having a first carbon dioxide concentration between 0.2% and 12%.

[0071] Adjust the parameters of the supergravity reactor 12. Figure 4 Embodiments and Figure 5 In the first cycle of the embodiment, the high gravity factor of the high gravity rotating packed bed is set to 50-139, and the gas flow rate (Q G ) is set to 28~72LPM, the flow rate of mixed wastewater (Q L ) is set to 0.18~0.8LPM, the flow rate of gas and mixed wastewater (Q G / Q L ) ratio is 45 to 400. Figure 5 From the second cycle of the embodiment, the high gravity factor of the high gravity rotating packed bed is set to 50 to 250, preferably 139 to 250, the gas flow rate is set to 36 LPM, and the flow rate of the mixed wastewater (Q L ) is set to 0.6~1LPM, the flow rate of gas and mixed wastewater (Q G / Q L ) ratio is 30 to 60. The super gravity factor at the beginning of the second cycle can be greater than the super gravity factor of the first cycle, which can increase the carbon dioxide capture rate by 15%, and the flow rate ratio at the beginning of the second cycle can be less than the flow rate ratio of the first cycle, which can increase the carbon dioxide capture rate by 18%, so as to further remove the residual calcium ions in the alkaline recovery liquid that cannot be removed in the first cycle.

[0072] The gas and the mixed wastewater react in the supergravity reactor 12 due to gas-liquid contact to generate metal salt precipitate 15, alkaline recovery liquid 14 and treated gas 125. The second hardness of the alkaline recovery liquid 14 is lower than the first hardness of the wastewater, and the second carbon dioxide concentration of the treated gas 125 is lower than the first carbon dioxide concentration of the gas 121.

[0073] The difference between the continuous flow system 1 of the first embodiment of the present invention for removing wastewater hardness and capturing carbon dioxide and the circulating flow system 2 of the second embodiment is that: in the continuous flow system 1, as Figure 1 As shown in the process, the second hardness of the alkaline recovery liquid is determined, the composition of the metal salt precipitate is analyzed, and / or the second carbon dioxide concentration of the treated gas is analyzed. In this embodiment, thermogravimetric analysis (also known as thermogravimetric analysis or thermogravimetric analysis; Thermogravimetricanalysis, TGA) is used to confirm what substance the metal salt precipitate 15 is and the purity of the main substance, and the treated alkaline recovery liquid 14 is introduced into the membrane bioreactor (MBR) system via the third pump 131 for the next stage of treatment.

[0074] In the circulating flow system 2, if Figure 2 As shown in the process, confirm whether the hardness of the alkaline recovery liquid meets the requirement. If the hardness has not reached the ND standard, the alkaline recovery liquid is injected into the recovery temporary storage tank 13 through the fourth pump 132, and then the alkaline recovery liquid is injected into the wastewater mixing tank 11. The pH value thereof is determined by the pH measuring device 113 to determine whether it needs to be adjusted to an appropriate value (11.5-12.5), and then it is re-introduced into the ultra-gravity reactor 12 (i.e., the ultra-gravity rotating packed bed) to react with a new batch of gases until the hardness reaches the ND standard; in addition, the liquid flow rate of the mixed wastewater will affect the operation time. If the operation time exceeds 40 minutes, the reactor parameters are readjusted to find out the parameters that shorten the operation time.

[0075] Finally, the second hardness of the alkaline recovery liquid is measured, the composition of the metal salt precipitate is analyzed, and / or the second carbon dioxide concentration of the treated gas is analyzed. In this embodiment, thermogravimetric analysis (also known as thermogravimetric analysis or thermogravimetric analysis; Thermogravimetric analysis, TGA) is used to confirm what substance the metal salt precipitate 15 is and the purity of the main substance, and the treated alkaline recovery liquid 14 is introduced into a membrane bioreactor (MBR) system for the next stage of treatment.

[0076] Examples 1 to 34

[0077] In Examples 1 to 20, the hardness of the wastewater, the carbon dioxide content of the waste gas containing carbon dioxide, the pH value of the wastewater after preparation, the ratio of the gas flow rate to the liquid flow rate introduced into the reactor, the selected supergravity factor, and the efficiency of each embodiment after treatment are shown in Tables 1 to 3 below. In Examples 21 to 34, the hardness of the wastewater, the carbon dioxide content of the waste gas containing carbon dioxide, the pH value of the wastewater after preparation, the ratio of the gas flow rate to the liquid flow rate introduced into the reactor, the selected supergravity factor, the carbon dioxide efficiency of each embodiment, the number of cycles, and the cycle time are shown in Tables 4 to 6 below. The carbon dioxide content of the waste gas containing carbon dioxide introduced into the reactor actually varies depending on the process or time, and can be 1550ppm-2170ppm, but the present invention is not limited thereto.

[0078] In Examples 1 to 34, calcium ions in the wastewater react with carbon dioxide to react with Formulas 1 to 4 respectively:

[0079] Reaction 1: 2OH - +CO 2 →CO 3 2- +2H + (In alkaline environment)

[0080] Reaction 2: CaCl 2 →Ca 2+ +2Cl -

[0081] Reaction 3: Ca 2+ +CO 3 2- →CaCO 3(s) ↓

[0082] Reaction 4: Ca 2+ +2OH - +CO 2 →CaCO 3(s) ↓+2H + +2Cl -

[0083] The hardness used in the present invention is measured using EDTA (ethylenediaminetetraacetic acid) titration method; carbon dioxide is measured using NDIR (non-dispersive infrared) method, and any method known in the art may also be used for measurement, but the present invention is not limited thereto.

[0084] In the following Tables 1-3, Examples 1 to 20 show the results of continuous flow operation. The result of gas flow rate / liquid flow rate is also called gas-liquid ratio. The differences caused by various conditions can be compared in Examples 1 to 20. The calculation method of hardness removal rate is shown in Mathematical Formula 2:

[0085]

[0086] Among them, n i Indicates the total hardness of the wastewater in ppm / CaCO 3 , n o It indicates the total hardness of the treated wastewater in ppm / CaCO 3 .

[0087] The differences caused by various conditions can be compared in Examples 1 to 20, wherein the calculation method of the carbon dioxide removal rate is shown in Mathematical Formula 3:

[0088]

[0089] Among them, n i Indicates the ppm of carbon dioxide in the carbon dioxide-containing exhaust gas (i.e., the first carbon dioxide concentration), n o It indicates how many ppm of carbon dioxide is in the exhaust gas after the reaction with the gas (ie, the second carbon dioxide concentration).

[0090] Experimental Example 1: Different First Hardness

[0091] Table 1

[0092]

[0093] Experimental Example 2: Different flow ratios of the gas and the mixed wastewater

[0094] Table 2

[0095]

[0096] Experimental Example 3: Different hypergravity factors

[0097] Table 3

[0098]

[0099]

[0100] In Examples 21 to 34 of Table 4-6, the results shown are for circulating flow operations, and the results of gas flow rate / liquid flow rate are also called gas-liquid ratio. The differences caused by various conditions can be compared in Examples 21 to 34, where the hardness removal rate is calculated as shown in the above mathematical formula 2, and the carbon dioxide removal rate is calculated as shown in the above mathematical formula 3.

[0101] Experimental Example 4: Different Cycle Times

[0102] Table 4

[0103]

[0104] Experimental Example 5: Different hypergravity factors

[0105] Table 5

[0106]

[0107] Experimental Example 6: Different wastewater pH values

[0108] Table 6

[0109]

[0110] To simplify the description, although the second hardness and the second carbon dioxide concentration are not shown in Tables 1 to 6, their values ​​can be deduced by introducing the hardness removal rate and the carbon dioxide removal rate into Mathematical Formulas 2 to 3.

[0111] In the operation of the circulating flow in Examples 21 to 34 in Tables 4 to 6, the volume of liquid operated is fixed, preferably 60 liters. Therefore, different liquid flow rates result in different cycle times for the same number of cycles. In the circulating flow operation mode, multiple supergravity rotating packed beds can be selectively connected in series to achieve the goal of a hardness outlet of ND, or multiple supergravity rotating packed beds can be connected in parallel to achieve the goal of a hardness outlet of ND. When the carbon dioxide concentration is high enough, it can be carried out in series. If the carbon dioxide concentration is low, it needs to be carried out in parallel. When the gas and liquid enter the supergravity rotating packed bed, they will react in countercurrent or crosscurrent modes according to the equipment type.

[0112] The composition of the metal salt precipitates obtained in Tables 1 to 6 was confirmed by thermogravimetric analysis (also known as thermogravimetric analysis or thermogravimetric analysis; Thermogravimetric analysis, TGA). The TGA results showed that the main detection curve of calcium carbonate began to lose weight at 624.4 degrees. Therefore, the purity of calcium carbonate was judged to be 95.493%.

[0113] Please refer to Figure 6 , which is a comparison diagram of the method and system of the present invention for removing wastewater hardness and capturing carbon dioxide by ultra-gravity using different pH values ​​and alkaline liquids.

[0114] like Figure 6As shown, after the test, the 4-liter sample was adjusted to pH 11.5 and pH 12.5 using 9.25 mL and 43 mL of liquid alkali respectively. From the results, it can be seen that the carbon dioxide removal rates at pH 11.5 and pH 12.5 are 38% and 63% respectively. In addition, the present invention uses alkaline wastewater generated after the technology industry process to replace liquid alkali (NaOH) to adjust the pH value. The amount of liquid alkali added is 1-20 mL per liter of wastewater containing calcium ions, and the amount of alkaline wastewater added is 100-200 mL per liter of wastewater containing calcium ions, so as to further achieve the goal of treating waste with waste. After the test, the 4-liter sample was adjusted to pH 11.5 using 615 mL of alkaline wastewater, that is, the amount of added is 154 mL / L, and the effect is not far from the result of the test using liquid alkali. Whether to add liquid alkali or alkaline wastewater can be adjusted according to actual design requirements.

[0115] In summary, the method for reducing hardness in wastewater of the present invention can not only effectively reduce the hardness in wastewater, but also reduce carbon dioxide in waste gas. In addition, calcium carbonate with a purity of more than 95% can be obtained after the reaction, which can indeed achieve the purpose of the present invention and realize the effects of wastewater treatment, carbon emission reduction and industrial raw material recovery.

[0116] The above description is only a preferred embodiment of the present invention and cannot be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the claims and patent specifications of the patent application of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. A system for removing wastewater hardness and capturing carbon dioxide by ultra-gravity, characterized in that: Include: A wastewater mixing tank connected to a wastewater source, wherein the wastewater in the wastewater source contains metal ions and has a first hardness, and the wastewater mixing tank is used to mix the wastewater and an alkaline liquid to adjust the pH value of the wastewater to alkaline and form mixed wastewater; as well as A supergravity reactor is connected to the wastewater mixing tank and introduced with a gas having a first carbon dioxide concentration, wherein the supergravity reactor mixes the mixed wastewater and the gas at a flow rate ratio of the gas to the mixed wastewater of 30 to 400:1 to react and generate a metal salt precipitate, an alkaline recovery liquid and a treated gas; The alkaline recovery liquid has a second hardness, which is lower than the first hardness, and the treated gas has a second carbon dioxide concentration, which is lower than the first carbon dioxide concentration.

2. The system according to claim 1, characterized in that It further comprises: a recovery temporary storage tank, which is respectively connected to the supergravity reactor and the wastewater mixing tank, and is used to inject the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles.

3. The system according to claim 1, characterized in that The invention further comprises: a blower connected to the supergravity reactor so as to pass the gas containing the first carbon dioxide concentration into the supergravity reactor.

4. The system according to claim 1, characterized in that The wastewater contains calcium chloride.

5. The system according to claim 1, wherein: The gas is exhaust gas or air, and the first carbon dioxide concentration of the gas is 0.2-12%.

6. The system according to claim 1, characterized in that The alkaline liquid is alkaline waste water, sodium hydroxide or potassium hydroxide.

7. The system according to claim 1, characterized in that The supergravity factor of the supergravity reactor is 50-250.

8. The system of claim 1, wherein: The system has a carbon dioxide removal rate of 5.5-64% and / or a hardness removal rate of 8-99%.

9. A method for removing wastewater hardness and capturing carbon dioxide by high gravity, characterized in that: It includes the following steps: Injecting wastewater from a wastewater source into a wastewater mixing tank, the wastewater containing metal ions and having a first hardness, mixing the wastewater and an alkaline liquid in the wastewater mixing tank to adjust the pH value of the wastewater to alkaline, and forming mixed wastewater; as well as The mixed wastewater is injected into a supergravity reactor, and a gas having a first carbon dioxide concentration is introduced, wherein the supergravity reactor mixes the mixed wastewater and the gas at a flow ratio of the gas to the mixed wastewater of 30 to 400:1 to react and generate a metal salt precipitate, an alkaline recovery liquid and a treated gas; The alkaline recovery liquid has a second hardness, which is lower than the first hardness, and the treated gas has a second carbon dioxide concentration, which is lower than the first carbon dioxide concentration.

10. The method according to claim 9, characterized in that The method further comprises: injecting the alkaline recovery liquid into a temporary recovery tank, and injecting the alkaline recovery liquid into the wastewater mixing tank for a specific number of cycles.

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