A method for sink-increasing treatment of desulfurization wastewater

Abstract

The application discloses a kind of desulfurization wastewater's increase processing method of sink, for the problem of strong acidity of desulfurization wastewater, higher carbon dioxide partial pressure.Utilize sink increasing agent can realize wastewater sink, the percentage of weight of each component of sink increasing agent is as follows: calcium oxide 10-85%, apatite 10-85%, calcined dolomite 0.01-85%, limestone 0.01-85%, olivine 0.01-50%, sodium carbonate 0.01-10%, sodium bicarbonate 0.01-10%, potassium dihydrogen phosphate 1.00-40%, and the sum of weight ratio of above each component is 100%.By using the method of the application, the sink increasing agent is used to improve the alkalinity of desulfurization wastewater, significantly reduce the carbon dioxide partial pressure in wastewater, improve the absorption of carbon dioxide, realize the transformation of carbon source into carbon sink, and strictly control the weak alkaline of water body at the discharge end.The system can increase the absorption of carbon dioxide, realize the sink of desulfurization wastewater;The method can quickly dissolve the sink increasing agent, realize the quick sink effect;And the method can adjust the weak alkaline of water body at the discharge end, the weak alkaline of desulfurization wastewater with low pH after treatment can be directly discharged.

Description

Technical Field

[0001] This invention relates to the field of utilizing desulfurization wastewater or waste liquid from other industries and to the field of carbon sequestration, specifically to a method for carbon sequestration treatment of desulfurization wastewater. Background Technology

[0002] Currently, atmospheric carbon dioxide concentration is close to 420 ppm, and global carbon dioxide emissions are nearly 40 billion tons per year. Excessive carbon dioxide concentration will exacerbate climate change and cause environmental problems such as ocean acidification and global warming. Therefore, excessive carbon dioxide emissions need to be addressed.

[0003] Modern society has an ever-increasing demand for petrochemicals, resulting in a surge in petrochemical wastewater. Petrochemical wastewater, especially desulfurization wastewater, typically exhibits high carbon dioxide partial pressure (pCO2) and low pH. Direct discharge of such wastewater can negatively impact the local ecosystem, releasing carbon dioxide and causing water acidification. Therefore, it urgently requires treatment before discharge.

[0004] Carbon sinks refer to the absorption of carbon dioxide by water bodies, while carbon sink enhancement refers to increasing the water body's capacity to absorb carbon dioxide (i.e., increasing the carbon sink). Carbon sink enhancement can effectively increase the absorption of emitted carbon dioxide. Traditional carbon sink enhancers, such as natural minerals like olivine, have slow dissolution rates and require high-energy fine grinding to improve their dissolution rate. Summary of the Invention

[0005] This invention addresses the problems of high carbon dioxide partial pressure and low pH in wastewater generated from petrochemical industries by proposing a method for enhancing carbon sink capacity in desulfurization wastewater. This invention enables rapid carbon sink enhancement, reducing the carbon dioxide partial pressure of the treated desulfurization wastewater to below 200 ppm. It effectively absorbs carbon dioxide, converting the carbon source into a carbon sink. Furthermore, the pH of the water after both the enhancement and aeration treatments can be controlled to a slightly alkaline level, allowing for direct discharge and multiple cycles of recycling.

[0006] This invention increases the alkalinity (TA) of desulfurization wastewater by using an alkaline carbon sequestration agent, thereby reducing pCO2 and enhancing its carbon sequestration capacity. This significantly improves the absorption capacity of carbon dioxide. At the same time, by adjusting TA and DIC, the pH of the solution is maintained within the weakly alkaline range to meet the discharge conditions. This invention enables rapid carbon sequestration.

[0007] This invention provides a method for enhancing the carbon dioxide absorption capacity of desulfurization wastewater. The method utilizes the desulfurization wastewater to dissolve an enhancer and absorb carbon dioxide. The enhancer comprises the following components by weight percentage: calcium oxide 10-85%, apatite 10-85%, calcined dolomite 0.01-85%, limestone 0.01-85%, olivine 0.01-50%, sodium carbonate 0.01-10%, sodium bicarbonate 0.01-10%, and potassium dihydrogen phosphate 1.00-40%. The sum of the weight percentages of all the above components is 100%.

[0008] The method specifically includes the following steps:

[0009] 1) Dissolve the above-mentioned sinking agent in desulfurization wastewater, stir and activate it thoroughly to completely dissolve the sinking agent, and obtain an alkaline system with alkalinity TA>2200μmol / L and pCO2<200ppm;

[0010] 2) Pass carbon dioxide-containing gas into the alkaline system obtained in step 1) to perform an absorption operation and absorb carbon dioxide;

[0011] 3) When the alkalinity of the alkaline system drops below 2200 μmol / L or the pCO2 of the solution rises above 500 ppm, stop the carbon dioxide addition or return to step 1) to add more carbon dioxide addition agent and repeat the carbon dioxide addition operation.

[0012] As a preferred embodiment of the present invention, in step 1), before adding the admixture, the salinity of the desulfurization wastewater is prepared to be 25‰-35‰; more preferably, sodium chloride is used to prepare the salinity of the desulfurization wastewater to be 30‰-35‰.

[0013] As a preferred embodiment of the present invention, in step 2), the temperature for absorbing carbon dioxide is 25°C and the pressure is atmospheric pressure.

[0014] As a preferred embodiment of the present invention, in step 1), the amount of the additive added per liter of wastewater is 5-20g; during activation, the stirring speed is 800-1200rpm.

[0015] As a preferred embodiment of the present invention, in step 1), the stirring activation time is 0.5-1h.

[0016] As a preferred embodiment of the present invention, in step 3), when the TA value of the alkaline system decreases to 2200 μmol / L or pCO2 > 500 ppm, a new alkaline reaction system is replaced.

[0017] As a preferred embodiment of the present invention, the highly alkaline system can be used to absorb carbon dioxide from the gas to be treated in a multi-stage series configuration to ensure that the final carbon dioxide concentration meets the requirements. Furthermore, a gas distributor or aeration device can be added to the highly alkaline system to enhance the absorption effect of carbon dioxide. Preferably, in step 2), the flow rate of the gas to be treated is 20-60 ml / min.

[0018] As a preferred embodiment of the present invention, the calcium oxide, magnesium oxide, and calcined dolomite are pre-ground to 40-200 mesh before being assembled.

[0019] As a preferred embodiment of the present invention, the calcined dolomite is dolomite that has been fully calcined at 650-850°C.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) This invention significantly increases the alkalinity of desulfurization wastewater through an alkaline carbon sequestration enhancer. By increasing the system's alkalinity and adjusting DIC, the pCO2 of the system is significantly reduced, enhancing its carbon sequestration function and achieving carbon dioxide absorption. The pCO2 of this invention can be reduced to 200 ppm, improving carbon dioxide absorption. Therefore, the carbon sequestration enhancer of this invention significantly enhances the carbon sequestration function of desulfurization wastewater. Unlike traditional techniques that use carbon fixation agents for chemical carbon fixation reactions, this invention enhances the entire system's physical absorption capacity of carbon dioxide.

[0022] 2) This invention utilizes a naturally acidic desulfurization wastewater system and adjusts the system to a higher salinity to promote the dissolution of the sinking agent. Under acidic conditions, the dissolution rate of the alkaline sinking agent is accelerated; furthermore, the high salinity system also helps to accelerate the dissolution rate of the sinking agent. The high salinity and acidic desulfurization wastewater system promotes the dissolution of the sinking agent, accelerates the sinking rate, and achieves rapid sinking. Furthermore, during the circulation process, the introduction of carbon dioxide acidifies the solution, which further promotes the dissolution of subsequently added sinking agents, achieving rapid sinking.

[0023] 3) This invention can adjust the alkalinity and DIC of the system by controlling the ratio and dosage of the added sinking agent, as well as the aeration time and flow rate. It can also adjust the pH of the system during the sinking process, the aeration process, and the repeated circulation process, thereby controlling the pH of the final discharge water to be weakly alkaline. Acidic desulfurization wastewater can be directly discharged after this treatment. Attached Figure Description

[0024] Figure 1 A diagram showing the changes in TA and pCO2 during the process of increasing foreign exchange reserves using foreign exchange enhancers;

[0025] Figure 2 A comparison chart of the rate of increase in the amount of foreign exchange deposits (FOD) between the foreign exchange deposit enhancer and olivine.

[0026] Figure 3 This is a comparison chart showing the rate of mass accumulation in desulfurization wastewater and pure water with the same amount of mass accumulation agent. Detailed Implementation

[0027] The present invention will be further described and illustrated below with reference to specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0028] This invention can be implemented in the following ways:

[0029] 1) Pre-grind calcium oxide, apatite, olivine, calcined dolomite, etc. to 40-400 mesh.

[0030] 2) The weight percentages of each component in the additive are as follows: calcium oxide 10-85%, apatite 10-85%, calcined dolomite 0.01-85%, limestone 0.01-85%, olivine 0.01-50%, sodium carbonate 0.01-10%, sodium bicarbonate 0.01-10%, and potassium dihydrogen phosphate 1.00-40%. The sum of the weight percentages of the above components is 100%.

[0031] 3) Configure the desulfurization wastewater system by adjusting the amount of sodium chloride, sodium sulfate, sodium fluoride, potassium chloride, potassium bromide, strontium chloride or dipotassium hydrogen phosphate added to make the salinity of the desulfurization wastewater 10‰~35‰.

[0032] 4) Dissolve the additives separately in the above system, and activate by stirring at 1200 rpm for 1 hour to obtain a high-alkalinity system with low pCO2. Figure 1 );from Figure 1 It is evident that the carbon dioxide absorption agent of the present invention can significantly increase the alkalinity of the wastewater system, reduce the pCO2 of the system, and improve the system's ability to absorb carbon dioxide, thereby achieving the absorption of introduced carbon dioxide.

[0033] 5) Introduce carbon dioxide into the above high alkalinity system at a flow rate of 20-200 ml / min. Stop when the TA value decreases to 2200 μmol / L or pCO2 > 500 ppm; or add a new sinking agent; or further replace the system with a new one for carbon dioxide absorption.

[0034] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0035] Example 1

[0036] Before adding the additive, the salinity of the desulfurization wastewater (alkalinity TA = 1981.2 μmol / L, DIC = 1869.2 μmol / L, pH = 5.13, pCO2 = 1156.5 ppm) was adjusted to 28.52‰.

[0037] 1) After pulverizing calcium oxide, apatite, olivine, and calcined dolomite, pass them through a 400-mesh sieve. Weigh out 0.4g of calcium oxide, 0.1g of apatite, 0.15g of calcined dolomite, 0.15g of olivine, 0.1g of potassium dihydrogen phosphate, 0.05g of sodium carbonate, and 0.05g of sodium bicarbonate, and mix them thoroughly to obtain 1g of additive.

[0038] 2) Take 1L of desulfurization wastewater, add 1g of carbon dioxide enhancer, stir at 800rpm for 1 hour to dissolve, the TA of the system rises to about 2700μmol / L, the DIC of the solution is 1916.5μmol / L, the pCO2 of the solution is 84.8ppm, and the pH of the solution is 8.778. At this time, the solution is weakly alkaline and can be discharged directly.

[0039] 3) After stirring and activation, carbon dioxide is introduced for absorption at a flow rate of 40 ml / min. The reaction is stopped when the system TA drops to 2100 μmol / L. The solution DIC is 1997.3 μmol / L, the solution pCO2 is 398.7 ppm, and the pH is 8.178. A total of 0.612 g CO2 is absorbed in this process. After aeration, the solution pH is 8.178, which is weakly alkaline and can be directly discharged.

[0040] Example 2

[0041] Before adding the additive, the salinity of the desulfurization wastewater (alkalinity TA = 1981.2 μmol / L, DIC = 1869.2 μmol / L, pH = 5.13, pCO2 = 1156.5 ppm) was adjusted to 28.52‰.

[0042] 1) After pulverizing calcium oxide, apatite, olivine, and calcined dolomite, pass them through a 400-mesh sieve. Weigh out 0.2g of calcium oxide, 0.1g of apatite, 0.15g of calcined dolomite, 0.35g of olivine, 0.15g of potassium dihydrogen phosphate, 0.05g of sodium carbonate, and 0.05g of sodium bicarbonate, and mix them thoroughly to obtain 1g of additive.

[0043] 2) Take 1L of desulfurization wastewater, add 1g of carbon dioxide enhancer, stir at 800rpm for 1 hour to dissolve, the TA of the system rises to about 2500μmol / L, at this time the DIC of the solution is 1914.2μmol / L, the pCO2 of the solution is 120.4ppm, the pH of the system is 8.641, and it can be discharged directly.

[0044] 3) After stirring and activation, high-purity carbon dioxide was introduced at a flow rate of 80 ml / min. The reaction was stopped when the system TA dropped to 2200 μmol / L. At this point, the solution DIC was 1937.4 μmol / L, pCO2 was 367.5 ppm, and pH was 8.225. A total of 0.451 g CO2 was absorbed in this process. After aeration, the solution pH was 8.225, which is weakly alkaline and can be directly discharged.

[0045] Example 3

[0046] Before adding the additive, the salinity of the desulfurization wastewater (alkalinity TA = 1912.2 μmol / L, DIC = 1868.0 μmol / L, pH = 4.87, pCO2 = 1311.5 ppm) was adjusted to 28.15‰.

[0047] 1) After pulverizing calcium oxide, apatite, olivine, and calcined dolomite, pass them through a 400-mesh sieve. Weigh out 0.35g of calcium oxide, 0.2g of apatite, 0.1g of calcined dolomite, 0.1g of olivine, 0.15g of potassium dihydrogen phosphate, 0.05g of sodium carbonate, and 0.05g of sodium bicarbonate, and mix them thoroughly to obtain 1g of additive.

[0048] 2) Take 1.5L of desulfurization wastewater, add 1g of carbon dioxide enhancer, stir at 800rpm for 1 hour to dissolve, the TA of the system increases to about 2600μmol / L, the DIC of the solution is 1895.5μmol / L, the pCO2 is 98.3ppm, the pH of the system is 8.718, which is weakly alkaline and can be discharged directly.

[0049] 3) After stirring and activation, high-purity carbon dioxide was introduced at a flow rate of 80 ml / min. The reaction was stopped when the system TA dropped to 2100 μmol / L. At this point, the solution DIC was 1934.9 μmol / L, pCO2 was 460.3 ppm, and the solution pH was 8.128. A total of 0.411 g CO2 was absorbed in this process. After aeration, the solution pH was 8.128, which is weakly alkaline and can be directly discharged.

[0050] Comparative Example 1

[0051] 1 L of desulfurization wastewater (alkalinity TA = 1912.2 μmol / L, DIC = 1868.0 μmol / L, pH = 4.87, pCO2 = 1311.5 ppm) was taken without any additives. The solution was stirred at 800 rpm for 1 hour, resulting in a decrease in pCO2 to 1246 ppm and the release of 0.00101 g CO2.

[0052] Comparative Example 2

[0053] Before adding the additive, the salinity of the desulfurization wastewater (alkalinity TA = 1912.2 μmol / L, DIC = 1868.0 μmol / L, pH = 4.87, pCO2 = 1311.5 ppm) was adjusted to 28.15‰.

[0054] 1) Crush the peridot and pass it through a 400-mesh sieve, then weigh out 1g of peridot.

[0055] 2) Take 1L of desulfurization wastewater, add 1g of olivine, stir at 800rpm for 1 hour to dissolve, the TA of the system increases to about 2300μmol / L, the pCO2 of the solution is 231.3ppm, and the pH is 8.405.

[0056] 3) After stirring and activation, high-purity carbon dioxide was introduced at a flow rate of 80 ml / min. The reaction was stopped when the TA of the system dropped to 2100 μmol / L. At this point, the pCO2 of the solution was 465.3 ppm and the pH was 8.121. A total of 0.131 g of CO2 was absorbed in this process. Figure 2 This is a comparison of the rate of increase in exchange rates between Example 1 and Comparative Example 2. From... Figure 2 It can be seen that, keeping the total alkalinity of the added sinking agent and olivine the same, after 60 minutes, the alkalinity increase value ΔTA of the group with added sinking agent (Example 1) was higher than that of the group with only olivine added (Comparative Example 2). This shows that the sinking agent of the present invention has a higher sinking rate than the traditional sinking agent olivine.

[0057] In summary, as seen in Examples 1-3, the carbon sink enhancer of this invention can significantly increase the alkalinity of the wastewater system, reduce the system's pCO2, and improve the system's ability to absorb carbon dioxide, enabling the system to absorb the introduced carbon dioxide. Furthermore, the proportion, dosage, aeration time, and flow rate of the enhancer can be controlled during the enhancement and aeration processes to adjust the system's alkalinity and DIC, and regulate the system's pH during the enhancement, aeration, and repetition processes, ensuring the discharged water is weakly alkaline and can be directly discharged. Simultaneously, our carbon sink enhancer transforms the wastewater system from a "carbon source" to a "carbon sink." Without any treatment, the wastewater system, due to its high carbon dioxide partial pressure, will directly release carbon dioxide (Comparative Example 1). However, the wastewater system treated with the enhancer exhibits high alkalinity and low pCO2, enabling it to absorb carbon dioxide (Examples 1-3), thus achieving carbon sink enhancement. Figure 1 Compared to conventional carbon dioxide absorption enhancers (Comparative Example 2), after the same time period, the carbon dioxide absorption enhancer of this invention increases alkalinity more significantly and enhances the system's ability to absorb carbon dioxide. Figure 2 Meanwhile, using desulfurization wastewater to dissolve the carbon dioxide enhancer can increase the carbon dioxide enhancement rate of the enhancer. Figure 3 ).

[0058] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for enhancing the treatment of desulfurization wastewater, characterized in that, The method specifically includes the following steps: 1) Prepare a sinking agent, wherein the weight percentages of each component of the sinking agent are as follows: calcium oxide 10-85%, apatite 10-85%, calcined dolomite 0.01-85%, limestone 0.01-85%, olivine 0.01-50%, sodium carbonate 0.01-10%, sodium bicarbonate 0.01-10%, and potassium dihydrogen phosphate 1.00-40%, and the sum of the weight percentages of the above components is 100%; dissolve the above sinking agent in desulfurization wastewater, stir thoroughly to activate it, and ensure that the sinking agent is completely dissolved to obtain an alkaline system with alkalinity TA > 2200 μmol / L and pCO2 < 200 ppm; 2) Pass carbon dioxide-containing gas into the alkaline system obtained in step 1) to perform an absorption enhancement operation and absorb carbon dioxide; 3) When the alkalinity of the alkaline system drops below 2200 μmol / L or the pCO2 of the solution rises above 500 ppm, stop the carbon dioxide addition or return to step 1) to add more carbon dioxide addition agent and repeat the carbon dioxide addition operation.

2. The method according to claim 1, characterized in that... In step 1), before adding the admixture, use one or more of sodium chloride, sodium sulfate, sodium fluoride, potassium chloride, potassium bromide, strontium chloride, or dipotassium hydrogen phosphate to prepare the desulfurization wastewater with a salinity of 10‰-35‰.

3. The method according to claim 1, characterized in that... In step 2), the temperature for absorbing carbon dioxide is 25°C and the pressure is atmospheric pressure.

4. The method according to claim 1, characterized in that... In step 1), the amount of additive added per liter of desulfurization wastewater is 0.5-20g; during activation, the stirring speed is 300-1400rpm.

5. The method according to claim 1, characterized in that... In step 1), the stirring activation time is 0.5-2 hours.

6. The method according to claim 1, characterized in that... In step 2), the flow rate of the carbon dioxide-containing gas is 20-200 ml / min.

7. The method according to claim 1, characterized in that: The calcium oxide, apatite, limestone, olivine, sodium carbonate, sodium bicarbonate, and calcined dolomite are pre-ground to 40-400 mesh before being assembled.

8. The method according to claim 1, characterized in that: The calcined dolomite is dolomite that has been fully calcined at 650-850℃.

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