A high concentration of difficult biochemical wet felt wastewater pretreatment system and method

Abstract

The application discloses a high-concentration difficult-biodegradation wet felt wastewater pretreatment system and method, which comprises the following steps: firstly, using a compound demulsifier to demulsify the wastewater, and then using kiln flue gas to treat the wastewater, so that the wet felt wastewater is pretreated by the method, the treatment of the high-difficulty wet felt wastewater is completed at the lowest cost, a technical breakthrough of the wet felt wastewater treatment is realized, the content of bactericides and white glue is reduced, the influence of the wet felt wastewater on a biochemical system of sewage treatment is reduced or eliminated, the wet felt wastewater can meet the acceptance standard of the sewage treatment, the impact on an existing sewage treatment system is eliminated, and the influence on the environment is reduced.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and in particular relates to a pretreatment system and method for high-concentration, biodegradable wet scrubbing wastewater. Background Technology

[0002] There are few wet-process felt production projects both domestically and internationally, and wet-process felt wastewater treatment technology is scarce. According to relevant treatment experience, a mixed treatment method is generally adopted, which involves mixing the wire drawing wastewater with the wet-process felt wastewater to reduce the influent concentration, and then using a "physicochemical + biological" treatment method.

[0003] The main components of wet-process felt wastewater are white glue, hydroxyethyl cellulose, CIT / MIT (bactericide), hexadecylamine bromide, organosilicon defoamer, and dispersant. The wastewater is emulsion-like, contains a small amount of glass fiber, and has a COD value of approximately 8000 mg / L.

[0004] The wastewater from wet-process felting is complex in composition and its emulsion form is difficult to break down. Among them, white glue and bactericide have the greatest impact on the biological system. White glue will adhere to the bacterial flocs in the aerobic system and accumulate continuously, leading to the inactivation and death of the bacteria. The chemical composition of the bactericide is a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. It has a large molecular weight and is difficult to be biodegraded. Summary of the Invention

[0005] To address the problem of complex composition and difficulty in treating wet-process felt wastewater, this invention provides a pretreatment system and method for high-concentration, recalcitrant wet-process felt wastewater. It utilizes a novel demulsifier to treat the wastewater and leverages kiln flue gas to treat the production wastewater, achieving the treatment of high-concentration, recalcitrant wet-process felt wastewater at the lowest cost, thus realizing a technological breakthrough in wet-process felt wastewater treatment. To achieve the above objectives, this invention provides the following technical solution:

[0006] As a first aspect of the present invention, it is to provide a pretreatment system for high-concentration, recalcitrant wet-process felt wastewater.

[0007] Equalization tank: Water from the workshop is pumped into the equalization tank and homogenized and homogenized under aeration conditions;

[0008] In the demulsification and flocculation tank, a demulsifier is added to break the emulsion in the wastewater, then an alkaline solution is added to adjust the pH to 7-8, and finally an amide is added to increase the floc size.

[0009] Vertical flow sedimentation tanks are used to achieve mud-water separation;

[0010] clear pool;

[0011] The regulating tank, demulsification and flocculation tank, vertical flow sedimentation tank, and clear water tank are connected in sequence by pipelines, and water pumps are installed on the pipelines.

[0012] Preferably, it also includes a sludge thickening tank and a plate and frame sludge press. The sludge and water at the bottom of the vertical flow sedimentation tank enter the sludge thickening tank, and the generated sludge is pumped to the plate and frame sludge press for dewatering. The sludge is then transported off-site for disposal. The water in the upper layer of the sludge thickening tank is transferred to the equalization tank for recycling.

[0013] Further, the flue gas treatment system also includes a flue gas treatment system connected to the clear water tank, which uses kiln flue gas to re-treat the wastewater, remove white glue, and deactivate the bactericide in the wastewater.

[0014] Preferably, the flue gas treatment mechanism includes a waste heat boiler, a boiler induced draft fan, and the boiler induced draft fan draws the flue gas from the waste heat boiler out, dividing it into two branches, including a first branch and a second branch. The first branch is connected to the flue gas treatment system via a pipeline, and the second branch is connected to a spray tower via a pipeline, and then to the flue gas treatment system. The spray tower includes a spray section at the top and a water collection section at the bottom. An electric butterfly valve, a blower, and a butterfly valve are sequentially installed on the branch between the boiler induced draft fan and the spray tower, connected to the spray tower for spraying. The lower part of the section; the top of the spray section of the spray tower is connected to the first branch line through a pipeline, and a butterfly valve is installed on the pipeline between the spray tower and the first branch line; the water from the clean water tank is divided into two paths after passing through a temporary storage tank and a wastewater control valve. One path goes through the spray pump and then into the spray section of the spray tower, while the other path goes directly into the bottom of the water collection section of the spray tower through a valve, realizing the recycling of liquid in the water collection section and liquid in the spray section; the bottom of the water collection section of the spray tower is also connected to the sewage treatment plant through a pipeline with a wastewater control valve and a sewage pump.

[0015] Furthermore, the spraying section of the spraying tower is provided with a flue gas outlet at the top, a demister at the top, and a spray gun at the side wall with the nozzle at the end of the spray gun pointing downwards; the side wall of the spraying section is also provided with an inspection door, and the bottom is provided with a flue gas inlet connected to the waste heat boiler; the bottom of the spraying section is connected to a water collection section, the inner diameter of the water collection section is larger than the inner diameter of the spraying section, the upper part of the water collection section is provided with an overflow port, and the bottom is provided with a spray outlet, a sewage outlet and a wastewater outlet, the wastewater outlet being connected to a sewage treatment plant.

[0016] As a second aspect of the present invention, a processing method is provided, comprising the following steps:

[0017] Step 1: The incoming water from the workshop is pumped into the equalization tank and homogenized under aeration conditions. Then it is pumped to the flocculation dosing tank. First, a demulsifier is added to break the emulsion in the wastewater. Then, liquid alkali is added to adjust the pH value to 7-8. Finally, amide is added to increase the floc size. After flocculation, the water flows by gravity into the vertical flow sedimentation tank to achieve sludge-water separation. The supernatant enters the clear water tank for further treatment using flue gas, and the bottom sludge enters the sludge tank for sludge pressing.

[0018] Step 2: Wastewater from wet-laid felt is first stored in a temporary storage tank, and then pumped into the spray section of the spray tower to react with the flue gas using a spray pump. After that, it falls into the bottom water collection section of the spray tower. By adjusting the valve, the wastewater in the water collection section can be repeatedly sprayed by the spray pump to react with the flue gas until the expected effect is achieved. After the treatment effect is achieved, the wastewater is pumped to the sewage treatment plant for further treatment.

[0019] In step one, if only a demulsifier is added, the demulsified flocs will be very small and the settling speed will be very slow. Therefore, sodium hydroxide needs to be added further to adjust the pH value to 7-8, and finally, a 5‰ concentration of cationic amide is added. Through the adsorption and bridging of the amide, the small flocs are enlarged, the settling speed is accelerated, and rapid oil-water separation is achieved. Through this synergistic effect, the demulsifier can effectively treat wet-process felt wastewater, achieve oil-water separation, reduce environmental pollution, and improve resource recycling rate.

[0020] Even after demulsifying the wastewater using this method, some bactericides and other substances still remain. Based on the characteristics of these bactericides, this invention effectively utilizes the kiln flue gas to further treat this type of wastewater.

[0021] Furthermore, the present invention also provides a demulsifier, wherein in step one, the demulsifier comprises 2-3% castor oil sulfate, 1-2% potassium stearate, 2-3% sodium hexadecyl sulfate, 1-2% calcium chloride, 1-2% ferric chloride, 3-5% methyl tert-butyl ether, 3-5% triethanolamine oleate, and 1-1.5% hydrochloric acid.

[0022] Demulsifiers are chemical additives specifically designed to disrupt the stability of emulsions, and are widely used in industrial wastewater treatment, oil extraction, food processing, and other fields. An emulsion is a dispersion system composed of two immiscible liquids (such as water and oil), where one liquid is dispersed in the other as tiny droplets. The function of a demulsifier is to break down this dispersion system through physical or chemical means, thereby achieving oil-water separation.

[0023] The roles of each component in a demulsifier:

[0024] Castor oil sulfate is an anionic surfactant with good wetting and dispersing abilities. During demulsification, it can react with the cationic components in the emulsifier, neutralizing their surface activity and disrupting the stability of the emulsion.

[0025] Potassium stearate is a commonly used anionic surfactant that promotes the aggregation and separation of oil droplets by reducing interfacial tension.

[0026] Sodium hexadecyl sulfate is a potent anionic surfactant that can significantly reduce interfacial tension and accelerate the aggregation of oil droplets, thereby achieving demulsification.

[0027] Calcium chloride, as an electrolyte, can reduce the stability of emulsifiers and promote demulsification by increasing the ionic strength in the solution.

[0028] Ferric chloride, also an electrolyte, can react with anionic surfactants in emulsifiers, disrupting the stability of the emulsifier and thus promoting demulsification.

[0029] Methyl tert-butyl ether, as an organic solvent, can dissolve emulsifiers, reduce their concentration at the oil-water interface, and help with demulsification.

[0030] Triethanolamine oleate is a nonionic surfactant that promotes the aggregation of oil droplets by altering interfacial tension and interfacial properties.

[0031] Hydrochloric acid, as an acidic substance, can neutralize alkaline substances in emulsions, alter the properties of emulsifiers, and thus disrupt the stability of the emulsion.

[0032] Synergistic demulsification effect:

[0033] In practical applications, a single demulsifier ingredient often fails to achieve the desired demulsification effect. Therefore, multiple demulsifier ingredients are usually used in combination to achieve a synergistic demulsification effect.

[0034] White glue, hydroxyethyl cellulose, silicone defoamers, and dispersants are common polymer monomers widely used in the manufacture of coatings, adhesives, and other products. When these substances form emulsions in water, they are difficult to separate naturally. In treating this type of wastewater, the addition of demulsifiers can effectively disrupt the stability of the emulsion and promote oil-water separation.

[0035] Specifically, anionic surfactants in demulsifiers (such as castor oil sulfate and sodium hexadecyl sulfate) can react with emulsifiers in wastewater, neutralizing their surface activity; while electrolytes (such as calcium chloride and ferric chloride) further promote oil droplet aggregation by increasing the ionic strength of the solution. In addition, the addition of organic solvents (such as methyl tert-butyl ether) and acidic substances (such as hydrochloric acid) can help disrupt the stability of emulsifiers and accelerate the demulsification process.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] This invention proposes a novel wastewater treatment method that uses a self-developed new demulsifier to treat wastewater and utilizes kiln flue gas to treat production wastewater. It achieves the treatment of high-concentration, difficult-to-biodegrade wet-process felt wastewater at the lowest cost, realizing a technological breakthrough in wet-process felt wastewater treatment, eliminating the impact on existing wastewater treatment systems (wastewater treatment plants), and reducing environmental impact.

[0038] This invention provides a specialized treatment for wet-process felt wastewater, improving wastewater treatment efficiency. The demulsifier independently developed by Ziru has a significant effect on this type of wastewater, and it is the first to attempt a process method that uses kiln flue gas to treat wastewater, achieving deep treatment of wet-process felt wastewater at the lowest investment cost and realizing comprehensive utilization of waste gas. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 This invention provides a schematic diagram of a pretreatment system for high-concentration, biodegradable wet-process felt wastewater.

[0041] Figure 2 This invention provides a structural diagram of a flue gas treatment mechanism in a pretreatment system for high-concentration, biodegradable wet felt wastewater.

[0042] Figure 3 This invention provides a schematic diagram of the spray tower structure in a pretreatment system for high-concentration, biodegradable wet felt wastewater.

[0043] Among them, 1. Waste heat boiler, 2. Boiler induced draft fan, 3. Butterfly valve, 4. Flue gas duct, 5. Electric butterfly valve, 6. Blower, 7. Spray tower, 8. Flue gas treatment system, 9. Clear water tank, 10. Temporary storage tank, 11. Wastewater control valve, 12. Spray pump, 13. Wastewater duct, 14. Sewage pump, 15. Sewage treatment station;

[0044] 4-1, First Branch Road; 4-2, Second Branch Road;

[0045] 7-1 Spray section, 7-2 Water collection section, 7-3 Demister, 7-4 Spray gun, 7-5 Nozzle, 7-6 Inspection door, 7-7 Flue gas inlet, 7-8 Flue gas outlet, 7-9 Spray outlet, 7-10 Wastewater outlet, 7-11 Overflow outlet, 7-12 Sewage outlet. Detailed Implementation

[0046] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0047] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0048] In response to the difficulty in demulsifying wet-process felt wastewater, the inventors developed a novel demulsifier through component research and numerous demulsification experiments. This demulsifier is a reverse demulsifier, a high-molecular-weight polymer. After being added, it reduces the stability of the interfacial membrane of the emulsion by stirring and colliding, thereby causing flocculation and aggregation, thus demulsifying. Subsequently, sodium hydroxide and cationic polyacrylamide are added to increase the size of the flocs and accelerate sedimentation.

[0049] Meanwhile, according to the product instructions for the bactericide, the suitable conditions for its use are: pH value 2.0-9.0 and temperature ≤60℃. In view of these conditions, it is considered to use the high-temperature kiln flue gas to deactivate the bactericide, and the sulfur dioxide in the flue gas will undergo a neutralization reaction after dissolving in water, which will promote the flocculation and sedimentation of white glue.

[0050] This invention proposes a technical method for treating wet-process felt wastewater. First, a compound demulsifier is used to demulsify the wastewater. Then, kiln flue gas is used to treat the wastewater. This method pre-treats the wet-process felt wastewater, achieving a technological breakthrough in treating this challenging wastewater at the lowest cost. It reduces the content of bactericides and white glue, lowers or eliminates the impact of wet-process felt wastewater on the wastewater treatment biological system, ensuring it meets wastewater treatment acceptance standards. It also eliminates the impact on existing wastewater treatment plants and avoids illegal discharge exceeding standards.

[0051] Because wet-process felt wastewater contains white glue, hydroxyethyl cellulose, CIT / MIT (bactericide), hexadecylamine bromide, silicone defoamer, dispersant, and other components, the wastewater is emulsion-like, contains a small amount of glass fiber, has a high COD value, and the emulsion state of the wet-process felt wastewater is difficult to break. In view of this, this invention, based on the characteristics of wet-process felt wastewater and the principle of "separate treatment," treats this wastewater separately, resulting in a technical method for treating wet-process felt wastewater. In a specific embodiment of this invention, a pretreatment system for high-concentration, recalcitrant wet-process felt wastewater is provided, comprising:

[0052] Equalization tank: Water from the workshop is pumped into the equalization tank and homogenized and homogenized under aeration conditions;

[0053] In the demulsification and flocculation tank, a demulsifier is added to break the emulsion in the wastewater, then an alkaline solution is added to adjust the pH to 7-8, and finally an amide is added to increase the floc size.

[0054] Vertical flow sedimentation tanks are used to achieve mud-water separation;

[0055] Clear water tank, used to store wastewater;

[0056] The flue gas treatment unit uses kiln flue gas to further treat wastewater, including removing white glue and deactivating bactericides in the wastewater.

[0057] It also includes sludge thickening tanks and plate and frame sludge presses to treat the sludge at the bottom of vertical flow sedimentation tanks.

[0058] The equalization tank, demulsification and flocculation tank, vertical flow sedimentation tank, and clear water tank are connected in sequence by pipelines, with water pumps installed on the pipelines. The clear water tank is connected to the flue gas treatment unit by a pipeline. The bottom pipeline of the vertical flow sedimentation tank is connected to the sludge thickening tank, and the sludge water is introduced into the sludge thickening tank. The sludge in the sludge thickening tank is pumped to the plate and frame sludge press by a sludge pump to filter out the water from the concentrated sludge and transport it for disposal. The water in the upper layer of the sludge thickening tank is transferred to the equalization tank for recycling.

[0059] In an embodiment of the present invention, a demulsifier is provided. This demulsifier is a reverse demulsifier, belonging to a high molecular weight polymer. After being added, it reduces the stability of the interfacial film of the emulsion by stirring and colliding, thereby causing flocculation and aggregation, and thus demulsifying. Its components are: "1. Castor oil sulfate 2-3%; 2. Potassium stearate 1-2%; 3. Sodium hexadecyl sulfate 2-3%; 4. Calcium chloride 1-2%; 5. Ferric chloride 1-2%; 6. Methyl tert-butyl ether 3-5%; 7. Triethanolamine oleate 3-5%; 8. Hydrochloric acid 1-1.5%".

[0060] In embodiments of the present invention, a structure for a flue gas treatment mechanism is provided, such as... Figure 2 and Figure 3 As shown, it includes a waste heat boiler 1, a boiler induced draft fan 2, a butterfly valve 3, a flue gas duct 4, an electric butterfly valve 5, a blower 6, a spray tower 7, a flue gas treatment system 8, and a wastewater system. The wastewater system includes a clear water tank 9, a temporary storage tank 10, a valve 11, a spray pump 12, a wastewater duct 13, a sewage pump 14, and a sewage treatment station 15. The spray tower consists of 7-1, a spray section, 7-2, a water collection section, 7-3, a demister, 7-4, a spray gun, 7-5, a nozzle, 7-6, an inspection door, 7-7, a flue gas inlet, 7-8, a flue gas outlet, 7-9, a spray outlet, 7-10, a wastewater outlet, 7-11, an overflow outlet, and 7-12, a sewage outlet.

[0061] Temporary storage tank 10 can store wet felt wastewater, which can be stored temporarily and prevent damage to the pump when the water volume is insufficient.

[0062] The boiler induced draft fan draws the flue gas from the waste heat boiler. The flue gas duct 4 is divided into two branches: a first branch 4-1 and a second branch 4-2. The first branch 4-1 is connected to the flue gas treatment system 8 via a pipe, and the second branch 4-2 is connected to the spray tower 7 via a pipe, and then to the flue gas treatment system 8. The spray tower 7 includes a top spray section 7-1 and a lower water collection section 7-2. An electric butterfly valve 5, a blower 6, and a butterfly valve 3 are sequentially installed on the branch between the boiler induced draft fan 2 and the spray tower 7, connecting to the lower part of the spray section 7-1 of the spray tower. The top of the spray section of the tower is connected to the first branch 4-1 via a pipe. A butterfly valve 3 is installed on the pipe between the spray tower and the first branch 4-1. The water from the clean water tank 9 is divided into two paths after passing through the temporary storage tank 10 and the wastewater control valve 11. One path passes through the spray pump 12 and enters the spray section 7-1 of the spray tower. The other path is directly connected to the bottom of the water collection section 7-2 of the spray tower through a valve, realizing the recycling of liquid in the water collection section and liquid in the spray section. The bottom of the water collection section of the spray tower is also connected to the sewage treatment station via a pipe with a wastewater control valve 11 and a sewage pump 14.

[0063] During system operation, butterfly valve 3 is normally open. An electric butterfly valve 5 is also installed on the branch between boiler induced draft fan 2 and spray tower 7 to adjust the flue gas intake at any time.

[0064] The spraying tower has a flue gas outlet 7-8 at the top of the spraying section, a demister 7-3 at the top, and a spray gun 7-4 through the side wall with the nozzle 7-5 at the end of the spray gun pointing downwards. The side wall of the spraying section also has an inspection door 7-6, and a flue gas inlet 7-7 connected to the waste heat boiler at the bottom. The spraying section is connected to a water collection section 7-2 below, with an inner diameter larger than that of the spraying section. An overflow port 7-11 is provided at the top of the water collection section, and a spraying outlet 7-9, a sewage outlet 7-12, and a wastewater outlet 7-10 are provided at the bottom. The wastewater outlet is connected to a sewage treatment plant.

[0065] The bottom water collection section 7-2 of the spray tower 7 is connected to the temporary storage tank 10 by the wastewater pipe 13. The spray pump 12 can control the extraction of wastewater from either the water collection section 7-2 or the temporary storage tank 10 for treatment through the wastewater control valve 11.

[0066] The spray section 7-1 is equipped with two layers of spraying, and the nozzles are selected with 120° wide-angle spiral nozzles to increase the contact time and contact area between flue gas and wet felt wastewater, so as to achieve a higher and better treatment effect.

[0067] A demister 7-3 is installed at the top of the spray tower 7, which can effectively intercept the wastewater entrained in the flue gas and prevent the wastewater from entering the original flue gas treatment system 8 and having an adverse effect on it.

[0068] The spray tower 7 is equipped with inspection doors 7-6 at the spray gun and bottom, which can be used to clean the blockages and sediments at the spray gun and bottom of the tower;

[0069] The spray tower 7 is also equipped with an overflow port 7-11 to prevent excessive water from affecting the system's operation; and a drain port 7-12 to facilitate the removal of debris after cleaning.

[0070] Operating steps:

[0071] 1. First, ensure that the amount of water entering the temporary storage tank 10 for the wet felt exhaust gas meets the start-up requirements, and open the valve at the outlet of the temporary storage tank. Start the spray pump 12 and set the start-up time according to the amount of wastewater in the temporary storage tank 10 to avoid evacuation and damage to the equipment.

[0072] 2. After transferring the wastewater from the temporary storage tank 10 to the water collection section 7-2 of the spray tower 7, stop the spray pump 12, switch the valve, and change the inlet of the spray pump 12 to the water collection section.

[0073] 3. Turn on spray pump 12 to circulate the wastewater in the spray tower; first turn on the wastewater system protection system to prevent high-temperature damage to the equipment caused by advanced flue gas;

[0074] 4. Open the electric butterfly valve 5 and slowly start the blower 6 to allow the flue gas to enter the spray tower and react with the wastewater being sprayed.

[0075] 5. After the reaction is complete, open the valve at the wastewater outlet 7-10, turn on the sewage pump 14, and pump the pretreated wastewater into the sewage treatment plant 15 for further treatment.

[0076] 6. When not in use, shut down the machine in the following order: first shut down the flue gas system, then shut down the wastewater spray system. When in use, turn it on again in the same order: first turn on the wastewater system, then turn on the flue gas system, and repeat the cycle.

[0077] Process principle:

[0078] The suitable operating conditions for the bactericide used by our company are: pH value 2.0-9.0, temperature ≤60℃. Washing with 200℃ flue gas from the waste heat boiler of the waste gas treatment station can deactivate this bactericide. Sulfur dioxide in the flue gas dissolves in water and undergoes a neutralization reaction, promoting the flocculation and sedimentation of white glue.

[0079] Because SO2 in flue gas reacts with water to form sulfurous acid, which neutralizes the alkaline wastewater and reduces its alkalinity, the pH value of the wastewater decreases significantly after the flue gas is introduced. The decrease in pH value will destroy the emulsifier (white glue) in the emulsion dispersion, which will lead to emulsion demulsification, floc formation, and precipitation, thus reducing the COD value of the wastewater.

[0080] Example 1,

[0081] Adopting such Figure 1The high-concentration, biodegradable wet-process felt wastewater pretreatment system shown in the diagram involves pumping incoming water into an equalization tank, homogenizing and equalizing it under aeration, and then pumping it to a flocculation dosing tank. First, a demulsifier is added to break up the wastewater emulsion, then liquid alkali is added to adjust the pH to 7-8, and finally amide is added to increase floc size. After flocculation, the water flows by gravity into a vertical flow sedimentation tank to achieve sludge-water separation. The supernatant enters a clear water tank for further treatment using flue gas, and the bottom sludge enters a sludge tank for pressing.

[0082] The components of the demulsifier used are:

[0083] 1. Castor oil sulfate 2-3%; 2. Potassium stearate 1-2%; 3. Sodium hexadecyl sulfate 2-3%; 4. Calcium chloride 1-2%; 5. Ferric chloride 1-2%; 6. Methyl tert-butyl ether 3-5%; 7. Triethanolamine oleate 3-5%; 8. Hydrochloric acid 1-1.5%.

[0084] Wastewater from the wet-process felt making process was collected, and the COD was measured to be 6080 mg / L. It was divided into seven groups (A-G), with 500 ml per group. Demulsifiers #1, #2, #3, #4, #5, #6, and #7 were used in experiments. 1 ml of demulsifier was added to every 500 ml of wastewater and stirred vigorously. Then, 1 ml of alkaline solution was added and stirred vigorously again. Finally, 1 ml of PAM (polyacrylamide) was added and stirred to enhance the flocculation effect and accelerate the flocculation speed. After sedimentation, the supernatant was collected and the COD was measured. In this example, a 30% sodium hydroxide solution was used as the alkaline solution. Other commonly used solutions, such as potassium hydroxide, can also be used.

[0085] Demulsifier components and content (%)

[0086]

[0087] The experimental results are shown in Table 1:

[0088] Table 1 Results of the demulsification experiment

[0089]

[0090]

[0091] Experimental principle: When a demulsifier is added to wastewater, the ion concentration in the liquid phase increases. Relatively speaking, the distance between the two ion layers is shortened, that is, the dynamic potential is reduced. When the demulsifier reaches a sufficient concentration, the dynamic potential of the particles is zero, the repulsive force disappears, and the attractive force between the particles becomes prominent. As a result, a large number of colloidal particles aggregate and settle out.

[0092] Experimental conclusion:

[0093] 1. This demulsifier can demulsify wet-process felt wastewater and remove a portion of the COD, making it suitable for the treatment of wet-process felt wastewater.

[0094] Flue gas route: The flue gas temperature after waste heat boiler 1 is approximately 200℃, which can deactivate the bactericide, meeting the usage requirements and not affecting the gas production of the waste heat boiler. Therefore, the flue gas after waste heat boiler 1 is selected to treat the wet felt wastewater. The flue gas contains sulfides such as sulfur dioxide formed by high-temperature combustion.

[0095] Wastewater route from wet-process felting: Wastewater 9 from wet-process felting is first stored in temporary storage tank 10, and then pumped into spray section 7-1 of spray tower 7 by spray pump 12 to react with flue gas, and then falls into the bottom collection section 7-2 of spray tower 7; by adjusting the valve 11, the wastewater in collection section 7-2 can be repeatedly sprayed by spray pump 12 to react with flue gas until the expected effect is achieved; after the treatment effect is achieved, the wastewater is pumped to wastewater treatment plant 15 by sewage pump 14 for further treatment.

[0096] First, select the location for flue gas to be drawn out and connected to the flue gas duct 4-1 after the boiler induced draft fan 2, so as to minimize the impact on the subsequent flue gas treatment system 8. Drawing out and connecting to the flue gas on the same straight pipe section is equivalent to drawing out a part of the flue gas and then returning it to the original position. Apart from reducing some sulfur dioxide and the temperature dropping to a certain extent after spraying, there is no other impact on the flue gas. The reduction in sulfur dioxide and a small amount of temperature has no impact on the subsequent waste gas treatment system.

[0097] An electric butterfly valve 5 is added to the flue gas duct 4-2 leading to the wastewater treatment to regulate the amount of exhaust gas drawn out. This portion of the flue gas is blown into the spray section 7-1 of the spray tower 7 by the induced draft fan 6, where it comes into contact with and reacts with the wet felt wastewater sprayed in the spray tower 7, eliminating the bactericides and white glue in the wet felt wastewater. The reacted flue gas exits through the top flue gas outlet 7-8 of the spray tower 7 and is then returned to the original flue gas duct, before entering the subsequent flue gas treatment system 8 for further treatment. The results of white glue removal after flue gas treatment are shown in Table 2.

[0098] Table 2 Results of white glue removal after flue gas treatment

[0099]

[0100]

[0101] Test on the inactivation of bactericide after flue gas introduction:

[0102] Experimental objective:

[0103] The bactericide contained in the company's wet-process felt wastewater is KLD-831, a chemical mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. Due to the difficulty in detecting this bactericide and the complexity of the equipment required, our laboratory lacks the necessary testing capabilities. This experiment indirectly tests the effect of flue gas introduction on the activity of the bactericide by measuring the biochemical oxygen demand (BOD) of the wastewater daily after flue gas is introduced, thus determining the wastewater treatment effect after flue gas introduction.

[0104] Experimental methods:

[0105] Experimental instruments and reagents:

[0106] Instruments and equipment: pH meter, constant temperature incubator.

[0107] Test metrics and methods:

[0108]

[0109] Experimental steps:

[0110] 1. Take an appropriate amount of wastewater from wet-process felting, filter to remove waste fibers, and sample to test pH, turbidity, COD, and BOD concentrations.

[0111] 2. Take 1000ml of filtered wastewater and divide it into two portions of 500ml each, placing them in separate beakers and labeling them N1 and N2.

[0112] 3. Introduce 200℃ flue gas into beaker N1 and let it stand for half an hour. Observe and compare the phenomena in the beaker, and take the supernatant to measure pH, BOD and COD.

[0113] 4. Select the wastewater downstream of the sewage outlet of the wastewater treatment plant as the inoculum, and use the dilution method for measurement. Take wastewater samples daily for 10 consecutive days to test the dissolved oxygen content.

[0114] Experimental conclusions and analysis

[0115] Experimental results:

[0116] The filtered wet scrubbing wastewater was milky white and quite turbid. Samples were taken and measured for turbidity, pH, and COD. The results were turbidity 664 NTU, pH 11, and COD 3882 mg / L.

[0117] After the flue gas was introduced, the dissolved oxygen content in the wastewater was measured daily to determine the daily biochemical oxygen demand. The data are shown in Table 3. It is clear that the biochemical oxygen demand of N1 wastewater is significantly higher than that of N2 wastewater without flue gas, indicating that the introduction of flue gas can effectively reduce the effect of bactericides and significantly improve the biodegradability of wastewater.

[0118] BOD5 / COD = 0.34, which meets the expected target.

[0119] Table 3 Summary of Daily Biochemical Oxygen Demand

[0120]

[0121] Experimental conclusion:

[0122] This experiment demonstrates that introducing flue gas can effectively reduce the activity of bactericides and significantly enhance the decomposition effect of biochemical bacteria on organic matter. High-temperature flue gas can disrupt the structure of bactericides, leading to the decomposition and inactivation of some derivatives.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating high concentration, non-biodegradable wet felt waste water, characterized by, Includes the following steps: Step 1: The incoming water from the workshop is pumped into the equalization tank and homogenized under aeration conditions. Then it is pumped to the flocculation dosing tank. First, a demulsifier is added to break the emulsion in the wastewater. Then, liquid alkali is added to adjust the pH value to 7-8. Finally, amide is added to increase the floc size. After flocculation, the water flows by gravity into the vertical flow sedimentation tank to achieve sludge-water separation. The supernatant enters the clear water tank for further treatment using flue gas, and the bottom sludge enters the sludge tank for sludge pressing. In step one, the demulsifier includes 2-3% castor oil sulfate, 1-2% potassium stearate, 2-3% sodium hexadecyl sulfate, 1-2% calcium chloride, 1-2% ferric chloride, 3-5% methyl tert-butyl ether, 3-5% triethanolamine oleate, and 1-1.5% hydrochloric acid.

2. The treatment method according to claim 1, characterized in that, It also includes a wastewater treatment step for flue gas: wastewater from wet-laid felt is first stored in a temporary storage tank, and then a spray pump is used to pump the wastewater into the spray section of the spray tower to react with the flue gas, and then it falls into the bottom water collection section of the spray tower; through valve adjustment, the wastewater in the water collection section is repeatedly sprayed by the spray pump to react with the flue gas until the expected effect is achieved; the wastewater after the treatment effect is achieved is pumped to the sewage treatment plant for further treatment by a sewage pump.

3. The treatment method according to any one of claims 1-2, characterized in that, A system for treating high-concentration, recalcitrant wet scrubbing wastewater includes: Equalization tank: Water from the workshop is pumped into the equalization tank and homogenized and homogenized under aeration conditions; In the demulsification and flocculation tank, a demulsifier is added to break the emulsion in the wastewater, then an alkaline solution is added to adjust the pH to 7-8, and finally an amide is added to increase the floc size. Vertical flow sedimentation tanks are used to achieve mud-water separation; clear pool; The regulating tank, demulsification and flocculation tank, vertical flow sedimentation tank, and clear water tank are connected in sequence by pipelines, and water pumps are installed on the pipelines.

4. The treatment method according to claim 3, characterized in that, It also includes a sludge thickening tank and a plate and frame sludge press. The mud and water at the bottom of the vertical flow sedimentation tank enter the sludge thickening tank, and the generated sludge is pumped to the plate and frame sludge press for dewatering. The sludge is then transported off-site for disposal. The water in the upper layer of the sludge thickening tank is transferred to the equalization tank for recycling.

5. The treatment method of claim 3, wherein It also includes flue gas treatment facilities that use kiln flue gas to further treat wastewater, deactivating the bactericides in the wastewater.

6. The treatment method according to claim 5, characterized in that, The flue gas treatment system includes a waste heat boiler and a boiler induced draft fan. The boiler induced draft fan draws the flue gas from the waste heat boiler and divides it into two branches, namely a first branch and a second branch. The first branch is connected to the flue gas treatment system through a pipeline, and the second branch is connected to a spray tower through a pipeline, and then to the flue gas treatment system.

7. The treatment method according to claim 6, characterized in that, The spray tower includes a top spray section and a lower water collection section. An electric butterfly valve, a blower, and a butterfly valve are sequentially installed on the branch line between the boiler induced draft fan and the spray tower, connecting to the lower part of the spray section. The top of the spray section is connected to the first branch line via a pipe, and a butterfly valve is installed on the pipe between the spray tower and the first branch line. Water from the clear water tank is branched into two paths after passing through a temporary storage tank and a wastewater control valve. One path passes through a spray pump and enters the spray section of the spray tower, while the other path directly enters the bottom of the water collection section of the spray tower via a valve, achieving the recycling of liquid between the water collection section and the spray section. The bottom of the water collection section of the spray tower is also connected to a wastewater treatment plant via a pipe equipped with a wastewater control valve and a sewage pump.

8. The treatment method according to claim 7, characterized in that, The spraying tower has a flue gas outlet at the top of the spraying section, a demister at the top, and spray guns inserted into the side wall with the nozzles at the end of the spray guns pointing downwards. The side wall of the spraying section also has an inspection door, and the bottom has a flue gas inlet connected to the waste heat boiler. The spraying section is connected to a water collection section below, and the inner diameter of the water collection section is larger than that of the spraying section. The water collection section has an overflow port at the top and a spray outlet, a sewage outlet, and a wastewater outlet at the bottom. The wastewater outlet is connected to a sewage treatment plant.

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