Enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling with sulfite

Abstract

The present application provides a method for enhancing sludge cell breaking and dehydration based on multi-stage electrochemical coupling with sulfite, which relates to the technical field of sludge dehydration and sludge resource recycling, including: using iron as an anode and titanium as a cathode, adding an auxiliary oxidizing agent to the sludge system to be dehydrated, and transferring it to the first-stage electrolytic reactor for electrolytic cell breaking and dehydration, wherein the auxiliary oxidizing agent includes sulfite; before the electrode reaches the preset passivation condition, the sludge in the first-stage electrolytic reactor is transferred to the next-stage electrolytic reactor to continue electrolytic cell breaking and dehydration; until the electrolysis in the multi-stage electrolytic reactor is completed, a flocculant is added to the sludge system for flocculation, and after flocculation, a filter press is performed to determine the moisture content of the mud cake to complete the dehydration. The present application solves the technical problem that the method for enhancing sludge cell breaking and dehydration by long-term monopolar electrochemical treatment is prone to electrode passivation, resulting in a decrease in reaction efficiency, and achieves the technical effect of further improving the dehydration rate of the sludge and realizing self-sustaining incineration of the sludge.

Description

Technical Field

[0001] The present application relates to the technical field of sludge dehydration and sludge resource recycling, and in particular to a method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite. Background Art

[0002] Sludge dehydration refers to reducing the water content in sludge by physical or chemical methods. In the field of sludge resource recovery, sludge deep dehydration technology, as a pre-incineration treatment technology, has gradually been recognized in the field of sludge treatment and disposal. After deep dehydration, the sludge can be incinerated without heating the source or incinerated with a slightly heated source, which can achieve maximum sludge reduction and energy recovery.

[0003] According to the way water combines with sludge particles, it can be divided into bound water and free water. Bound water can be further divided into interstitial water, surface water and bound water according to its different binding forces. Free water has a small attachment to sludge particles, while bound water is tightly bound to sludge particles. The energy required for different forms of water is different. Free water is easier to remove during the dehydration process. Bound water is one of the important factors that limit the efficiency of sludge dehydration. Removing this part of water requires a lot of energy, and the change trend of sludge moisture content when removing various water is related to it. The commonly used sludge dehydration method is to change the sludge floc structure by adding energy or agents, so that the water in the sludge is easier to separate and achieve the ultimate dehydration purpose. Among the many sludge pretreatment technologies, electrochemical treatment technology can retain organic matter in sludge, but the moisture content of the treated mud cake cannot meet the requirements of self-sustaining incineration; while some advanced oxidation systems. Such as sulfite, sulfate, persulfate system, etc. can achieve deep cell breaking and dehydration of sludge, but the organic matter content of the treated mud cake cannot meet the requirements of self-sustaining incineration.

[0004] Patent CN117361816A discloses a method for enhancing sludge cell disruption and dehydration by an electrochemical combined with an advanced oxidation system to address the above-mentioned problem. The sludge produced by the water plant is pre-treated by cell disruption using an electrochemical device using iron as the anode and titanium as the cathode in combination with an oxidizing agent, sodium sulfite. This reduces the moisture content of the mud cake produced by subsequent filter presses and removes TP in the filtrate. However, as the electrochemical reaction time increases, the sludge near the electrode plate will dry up and adhere to the surface of the electrode plate, causing electrode passivation and reduced electrochemical reaction efficiency. Summary of the invention

[0005] The present application provides a method for enhancing sludge cell rupture and dehydration based on multi-stage electrochemical coupling with sulfite, which solves the technical problem that the method for enhancing sludge cell rupture and dehydration by long-term single-pole electrochemical treatment is prone to electrode passivation, resulting in a decrease in reaction efficiency, and achieves the technical effect of further improving the sludge dehydration rate and realizing self-sustaining incineration of sludge.

[0006] In view of the above problems, the present application provides a method for enhanced sludge cell disruption and dehydration based on multi-stage electrochemical coupling of sulfite, the method comprising: using iron as an anode and titanium as a cathode, adding an auxiliary oxidizing agent to the sludge system to be dehydrated, and transferring it to a first-stage electrolytic reactor for electrolytic cell disruption and dehydration, wherein the auxiliary oxidizing agent comprises sulfite; before the electrode reaches a preset passivation condition, transferring the sludge in the first-stage electrolytic reactor to the next-stage electrolytic reactor for continued electrolytic cell disruption and dehydration; until the electrolysis in the multi-stage electrolytic reactor is completed, adding a flocculant to the sludge system for flocculation, and after flocculation, performing filter pressing to determine the moisture content of the mud cake to complete dehydration.

[0007] Preferably, the sulfite is sodium sulfite.

[0008] Preferably, the flocculant is polydimethyldiallylammonium chloride.

[0009] Preferably, the distance between the anode and cathode plates in each stage of the electrolysis reactor is 2 cm, and the electrolysis voltage is 15V.

[0010] Preferably, the auxiliary oxidizing agent also includes calcium chloride.

[0011] Preferably, the dosage of sodium sulfite in the auxiliary oxidizing agent is 40 mg / gDS, and the dosage of calcium chloride is 74 mg / gDS.

[0012] Preferably, the multi-stage electrolysis reactor includes a three-stage electrolysis reactor.

[0013] Preferably, the electrolysis cell rupture and dehydration reaction time in the three-stage electrolysis reactor is 10 minutes.

[0014] Preferably, the dosage of the polydimethyldiallylammonium chloride is 10.7 mg / gDS.

[0015] Preferably, the flocculated sludge system is filtered using filter press equipment and atmospheric pressure.

[0016] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0017] This application uses iron as the anode and titanium as the cathode, adds an auxiliary oxidizing agent to the sludge system to be dehydrated, and transfers it to the first-stage electrolytic reactor for electrolytic cell breaking and dehydration, wherein the auxiliary oxidizing agent includes sulfite; before the electrode reaches the preset passivation condition, the sludge in the first-stage electrolytic reactor is transferred to the next-stage electrolytic reactor to continue electrolytic cell breaking and dehydration; until the electrolysis in the multi-stage electrolytic reactor is completed, a flocculant is added to the sludge system for flocculation, and after flocculation, a filter press is performed to determine the moisture content of the mud cake to complete the dehydration. Compared with the method of strengthening sludge cell breaking and dehydration by long-term monopolar electrochemical treatment, this method avoids electrode passivation caused by long-term electrochemical reaction, further improves the dehydration rate of the sludge, reduces the moisture content of the mud cake produced by subsequent filter press, and maintains the organic matter content in the mud cake, so as to meet the requirements of self-sustaining incineration of sludge.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a process for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite provided in an embodiment of the present application;

[0020] FIG2 is a diagram showing the moisture content of the mud cake and the CST variation of the mud cake obtained after sludge pretreatment based on different electrode plate spacings in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiment of the present application;

[0021] FIG. 3( a ) and FIG. 3( b ) are diagrams showing the moisture content of the mud cake and the CST variation of the mud cake obtained after the sludge pretreatment is performed at different voltages in the method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite provided in the embodiment of the present application;

[0022] FIG. 4( a ) and FIG. 4( b ) are diagrams showing the moisture content of the mud cake and the CST variation of the mud cake obtained after sludge pretreatment based on different sodium sulfite dosages in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiments of the present application;

[0023] FIG. 5( a ) and FIG. 5( b ) are diagrams showing the moisture content of the mud cake and the CST variation thereof obtained after sludge pretreatment based on different electrolyte calcium chloride dosages in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiments of the present application;

[0024] Figure 6A diagram showing the change in moisture content and solid content of the mud cake obtained after sludge pretreatment based on different reaction times in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiments of the present application;

[0025] Figure 7 The moisture content of the mud cake and the CST variation diagram obtained after the multi-stage combination mode treatment at different times in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiment of the present application;

[0026] Figure 8 A graph showing changes in organic matter content of sludge cakes obtained after treatment in different treatment modes in the method for enhanced sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite provided in an embodiment of the present application;

[0027] 9 is a diagram showing the moisture content of the mud cake and the CST variation of the mud cake obtained after sludge pretreatment based on the dosage of polydimethyldiallylammonium chloride (PDMDAAC) in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiment of the present application;

[0028] 10 is a diagram showing the moisture content of the mud cake and the CST variation after sludge pretreatment based on different pH values ​​in the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the examples of the present application.

[0029] Figure symbols: AAA is a three-level electrochemical treatment mode of 20min-20min-20min, AAC is a three-level electrochemical treatment mode of 20min-20min-10min, AA is a two-level electrochemical treatment mode of 20min-20min, ACC is a three-level electrochemical treatment mode of 20min-10min-10min, BCC is a three-level electrochemical treatment mode of 15min-10min-10min, CCC is a three-level electrochemical treatment mode of 10min-10min-10min, CCD is a three-level electrochemical treatment mode of 10min-10min-5min, DD is a two-level electrochemical treatment mode of 5min-5min, RS is raw mud, A is simple electrochemical conditioning, B is a monopolar electrochemical coupled sodium sulfite system conditioning, and C is a multi-stage electrochemical coupled sodium sulfite system - a three-level electrochemical system according to the reaction time of 10min-10min-10min. DETAILED DESCRIPTION

[0030] The embodiment of the present application provides a method for enhanced sludge cell rupture and dehydration based on multi-stage electrochemical coupling of sulfite, which solves the technical problem that the method for enhanced sludge cell rupture and dehydration by long-term single-pole electrochemical treatment is prone to electrode passivation resulting in a decrease in reaction efficiency, thereby achieving the technical effect of further improving the sludge dehydration rate and realizing self-sustaining incineration of sludge.

[0031] like Figure 1 As shown, the embodiment of the present application provides a method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite, the method comprising:

[0032] Step S1: using iron as an anode and titanium as a cathode, adding an auxiliary oxidizing agent into the sludge system to be dehydrated, and transferring it to the first-stage electrolytic reactor for electrolytic cell dehydration, wherein the auxiliary oxidizing agent includes sulfite.

[0033] Specifically, in an electrochemical system, the anode refers to the pole from which electrons flow out. Iron acts as a sacrificial anode here and is oxidized during the electrolysis process to generate ferrous ions. The cathode is the pole from which electrons flow in. Titanium has good corrosion resistance and is suitable as a cathode material. It will not be significantly corroded during the electrolysis process. Auxiliary oxidants will be oxidized during the electrolysis process to generate highly oxidizing substances, which help to break the sludge cells. Electrolytic cell breaking and dehydration refers to the process of generating oxidizing substances to destroy sludge cells through the electrolysis process, releasing water and organic matter in the cells, thereby improving the dehydration efficiency.

[0034] In this step, auxiliary oxidants are first added to the sludge system to be treated, and then transferred to the first-stage electrolysis reactor for electrolysis. The reactor is equipped with an iron anode and a titanium cathode, and the electrolyte solution contains sulfite. When the current passes through, the iron on the anode is oxidized to Fe 2+ ions, while sulfite is oxidized near the anode to produce SO4 2- Free radicals, which are highly oxidizing, can destroy the sludge cell wall and promote the cell rupture and dehydration of sludge. For example, when treating sludge produced by papermaking wastewater, this process can significantly improve the dehydration efficiency of sludge and reduce the subsequent treatment costs.

[0035] Step S2: before the electrode reaches the preset passivation condition, the sludge in the first-stage electrolytic reactor is transferred to the next-stage electrolytic reactor for further electrolysis, cell disruption and dehydration.

[0036] Specifically, the electrode will gradually passivate during the electrolysis process, that is, an oxide film will form on the surface, reducing the electrochemical activity. The preset passivation condition refers to the condition set to stop electrolysis or transfer sludge in order to avoid complete passivation of the electrode and affect the electrolysis efficiency.

[0037] During the electrolysis process, the passivation of the electrode is monitored. Once it approaches the preset passivation condition, that is, an oxide film begins to form on the electrode surface, affecting the electrolysis efficiency, the sludge is immediately transferred from the current electrolysis reactor to the next electrolysis reactor. This transfer process can avoid electrode passivation, and at the same time, the efficiency of sludge cell disruption and dehydration can be gradually improved by using multi-stage reactors. For example, in a sewage treatment plant, by setting up multi-stage reactors, the dehydration rate of sludge can be gradually improved, and ultimately the ideal dehydration effect can be achieved.

[0038] Step S3: until the electrolysis in the multi-stage electrolysis reactor is completed, a flocculant is added to the sludge system for flocculation, and after flocculation, a filter press is performed to determine the moisture content of the mud cake to complete dehydration.

[0039] Specifically, flocculants are chemical agents used to promote the aggregation of sludge particles. After the electrolytic cell disruption is completed, flocculants are added to the sludge system for flocculation reaction to promote the sludge particles to form larger flocs, which is convenient for the subsequent filter pressing process. The flocculation reaction is carried out in a six-in-one coagulation experiment mixer. The six-in-one coagulation experiment mixer device includes 6 mechanical stirring paddles, a reactor (glass beaker), and a control console. The console can control different stirring speeds and stirring times by setting specific programs. The flocculated sludge is filtered through a filter press to separate water from the sludge and measure the moisture content of the mud cake. This process not only improves the dehydration efficiency of the sludge, but also reduces the difficulty and cost of subsequent treatment.

[0040] Preferably, the sulfite is sodium sulfite.

[0041] Specifically, in a preferred embodiment, the sulfite described in step S1 is selected from sodium sulfite. Sodium sulfite (Na2SO3) is a commonly used sulfite with good redox properties. Compared with other sulfites, its molecular structure is more easily oxidized to generate SO42- free radicals with strong oxidizing properties, and will not be over-oxidized to form other products that are not easy to participate in the reaction. Sodium sulfite has good solubility in water, which can ensure uniform distribution in the electrolysis system and improve the efficiency of the oxidation reaction. At the same time, because it is relatively stable in aqueous solution, it is easy to store and handle, which makes it more convenient in practical applications. In addition, the production cost of sodium sulfite is relatively low, and it is easy to purchase on a large scale, which has cost advantages in industrial production applications.

[0042] Preferably, the flocculant is polydimethyldiallylammonium chloride.

[0043] Specifically, in a preferred embodiment, the flocculant described in step S3 can be polydimethyldiallyl ammonium chloride (PDMDAAC). Polydimethyldiallyl ammonium chloride (PDMDAAC) has a cationic quaternary ammonium salt group, which produces a strong electrostatic attraction with anionic particles, so that it has excellent flocculation performance. Compared with the common flocculant polyacrylamide (PAM), polydimethyldiallyl ammonium chloride (PDMDAAC) still has stable flocculation performance under high salinity, acidic or alkaline conditions, and is suitable for complex water quality and sludge flocculation conditions, and the dosage of polydimethyldiallyl ammonium chloride (PDMDAAC) is low, which can reduce the treatment cost.

[0044] Preferably, the distance between the anode and cathode plates in each stage of the electrolysis reactor is 2 cm, and the electrolysis voltage is 15V.

[0045] Specifically, as shown in Figure 2(a) and Figure 2(b), the plate spacing is one of the factors affecting the dehydration effect. Under the original conditions of 90% moisture content, 165.5 CST, 0.02988 gDS / g solid content, 109 mg / L SCOD, and 47.5 mg / L ammonia nitrogen. When the plate spacing is 2 cm, the mud cake moisture content is as low as 65.9%, and the moisture content reduction rate is as high as 26.7%; when the plate spacing is 2 cm, the CST is as low as 15.9, and the CST reduction rate is as high as 90.4%. It can be inferred that when the plate spacing is too large, the current becomes smaller, the cell rupture effect decreases, and the SCOD and ammonia nitrogen of the supernatant are as high as 851.7 mg / L and 81.5 mg / L, respectively.

[0046] As shown in Figure 3(a) and Figure 3(b), under the premise that the moisture content of the original mud cake is 90%, CST is 59.4, and the solid content is 0.02643gDS / g, the effect of voltage on the moisture content and CST of the mud cake shows a trend of first decreasing and then increasing. When the voltage is 15V, the moisture content and CST are the lowest, which are 56.7% and 16.9. Excessive voltage causes a large amount of divalent iron ions to seep out, resulting in iron hydroxide precipitation attached to the electrode surface, resulting in electrode passivation and a decrease in dehydration rate.

[0047] Therefore, when the distance between the anode and cathode plates in each electrolytic reactor is 2 cm and the electrolysis voltage is 15 V, the electrolysis cell rupture and dehydration effect is better.

[0048] Preferably, the auxiliary oxidizing agent also includes calcium chloride.

[0049] Specifically, in a specific embodiment, the auxiliary oxidizing agent in step S1 also includes calcium chloride. The Ca 2+It can combine with the negative charges on the surface of sludge particles to neutralize their charge state, thereby reducing the repulsion between particles, promoting the coagulation and flocculation of particles, forming larger flocs, and facilitating subsequent dehydration treatment. Common phenolic compounds and substances containing hydroxyl (-OH) functional groups in sludge systems usually have a certain degree of hydrophilicity and can absorb water. 2+ The combination with these substances can neutralize their negative charges and reduce their hydrophilicity; it also enhances the cohesion of particles through the bridging effect of protein, while reducing the adsorption of water by organic matter and deeply removing the bound water in the sludge.

[0050] The addition of calcium chloride forms a synergistic effect with oxidizing agents such as sodium sulfite. Sodium sulfite generates SO4 2- Free radicals destroy cell walls and release cell contents, while calcium chloride improves sludge structure and accelerates water separation by promoting flocculation and deep dehydration. Together, they significantly improve the efficiency of sludge cell disruption and dehydration.

[0051] Preferably, the dosage of sodium sulfite in the auxiliary oxidizing agent is 40 mg / gDS, and the dosage of calcium chloride is 74 mg / gDS.

[0052] Specifically, as shown in Figure 4(a) and Figure 4(b), under the premise that the moisture content of the original mud cake is 90%, the CST is 59.4, and the solid content is 0.02643gDS / g, the effect of the amount of sodium sulfite added on the moisture content and CST of the mud cake shows a trend of first decreasing and then increasing. When the dosage is 40mg / gDS, the moisture content and CST are the lowest, which are 52.7% and 13.1. Excessive sulfite will produce hydrogen persulfate radicals HSO5 - , which will react with the produced sulfate free radicals, thus affecting the dehydration effect.

[0053] As shown in Figure 5(a) and Figure 5(b), under the premise that the moisture content of the original mud cake is 90%, CST is 59.4, and the solid content is 0.02643gDS / g, the effect of the electrolyte calcium chloride dosage on the mud cake moisture content and CST shows a trend of first decreasing and then increasing. When the electrolyte calcium chloride dosage is 74mg / gDS, the moisture content and CST are the lowest, which are 48.8% and 14.1. Too much electrolyte will increase the current, increase the temperature, dry the sludge, and the sulfate will decompose at high temperature, further reducing the dehydration effect.

[0054] Therefore, when the dosage of sodium sulfite in the auxiliary oxidizing agent is 40 mg / gDS and the dosage of calcium chloride is 74 mg / gDS, the electrolytic cell rupture and dehydration effect is better.

[0055] Preferably, the multi-stage electrolysis reactor includes a three-stage electrolysis reactor.

[0056] Specifically, steps S1 to S2 of the embodiment of the present application are carried out in a multi-stage electrolysis reactor. The reaction device is an open reactor made of plexiglass. The reactor includes an iron-titanium electrode, a rotor agitator and a power supply. The iron-titanium electrode is used to electrolyze sludge, the rotor agitator is used to stir the sludge during the reaction, and the power supply is used to provide current and voltage to the iron-titanium electrode during the reaction.

[0057] In a specific embodiment, the multi-stage electrolysis reactor adopts a three-stage electrolysis reactor. In the three-stage electrolysis reactor, the sludge will pass through three different electrolysis units in sequence, and each unit can be set with the same or different operating parameters, such as current density, electrolysis time, dosage of reagents, etc., to achieve deep treatment of the sludge. Through three-stage continuous treatment, it can be ensured that the sludge is fully cell-broken at each stage, avoiding the problems of uneven treatment or insufficient efficiency that may exist in a single treatment unit. As the sludge passes through each electrolysis unit, the degree of cell destruction gradually increases, and finally reaches an ideal cell-broken and dehydrated state.

[0058] Preferably, the electrolysis cell rupture and dehydration reaction time in the three-stage electrolysis reactor is 10 minutes.

[0059] Specifically, if Figure 6 As shown in the figure, in the first 20 minutes of the electrochemical system reaction, the decrease in the moisture content of the mud cake is significantly greater than the decrease in the last 30 minutes. It can be concluded that a relatively high oxidation cell-breaking efficiency can be maintained in the first 20 minutes of the reaction. After 20 minutes, the electrochemical reaction efficiency drops significantly due to the gradual attachment of the dried sludge to the anode surface and the resistance passivation. Figure 7 As shown, the multi-stage combination mode is optimized according to the electrode passivation time, and experiments are carried out under 8 different modes, including 20min-20min-20min (AAA) three-stage electrochemical treatment mode, 20min-20min-10min (AAC) three-stage electrochemical treatment mode, 20min-20min (AA) two-stage electrochemical treatment mode, 20min-10min-10min (ACC) three-stage electrochemical treatment mode, 15min-10min-10min (BCC) three-stage electrochemical treatment mode, 10min-10min-10min (CCC) three-stage electrochemical treatment mode, 10min-10min-5min (CCD) three-stage electrochemical treatment mode, and 5min-5min (DD) two-stage electrochemical treatment mode. Considering that the moisture content of the mud cake should be controlled to below 50% while reducing the energy consumption as much as possible, the 10min-10min-10min three-stage electrochemical pretreatment system (total reaction time is 30min) is selected as the optimal reaction mode of the multi-stage electrochemical coupling system.

[0060] like Figure 8 As shown, the organic matter content of the original mud and the mud cake after three different conditioning methods were measured, among which the three different conditioning methods include: simple electrochemical conditioning (A), single-pole electrochemical coupling sodium sulfite system conditioning (B), multi-stage electrochemical coupling sodium sulfite system - three-stage electrochemical system with a reaction time of 10min-10min-10min (C). The organic matter content of the original mud and the mud cake after three different conditioning methods were 57.1%, 48.3%, 47.0%, and 51.5%, respectively. It can be seen that the organic matter content of the untreated sludge has reached the standard for self-sustaining incineration (>50%), but its moisture content is far from the standard; simple electrochemistry and monopolar electrochemistry coupled with sodium sulfite conditioning did not simultaneously meet the national standards for self-sustaining sludge incineration in terms of the two indicators of mud cake moisture content and organic matter content. It is speculated that this is because as the reaction time is too long, the electrode resistance increases due to passivation, the temperature of the reaction system rises significantly, and while the electrochemical treatment efficiency drops rapidly, the excessively high reaction temperature destroys part of the organic matter in the system, which ultimately leads to a decrease in the organic matter content in the mud cake. The multi-stage electrochemical system can reduce the above effects.

[0061] When the monopolar electrochemical treatment mode is optimized to a multi-stage electrochemical pretreatment mode, the moisture content of the obtained mud cake is further reduced through grading under the condition of the same total reaction time. At the same time, the total reaction time can be reduced under the premise of meeting the self-sustaining incineration standard of the sludge. The 10min-10min-10min three-stage electrochemical pretreatment system is the best multi-stage electrochemical treatment system under the premise of saving economic costs. The moisture content of the mud cake after treatment is 49.56%.

[0062] Preferably, the dosage of the polydimethyldiallylammonium chloride is 10.7 mg / gDS.

[0063] Specifically, as shown in Figures 9(a) and 9(b), as the dosage of polydimethyldiallyl ammonium chloride (PDMDAAC) increases, the moisture content and CST of the conditioned sludge show a trend of first decreasing and then increasing, and the optimal values ​​are 56.7% and 15.4 respectively at 10.7 mg / gDS. The flocs produced when the conditioned sludge flocculates are in smaller clusters, settle faster, and there is a clear stratification of mud and water. When the dosage increases, the moisture content of the mud cake increases. It is speculated that excessive polydimethyldiallyl ammonium chloride (PDMDAAC) causes the sludge viscosity to increase slightly. Therefore, when the dosage of polydimethyldiallyl ammonium chloride is 10.7 mg / gDS, the sludge dehydration effect is better.

[0064] In addition, the examples of the present application also explore the effect of pH on the sludge dewatering effect. As shown in Figure 10 (a) and Figure 10 (b), under the premise that the moisture content of the original mud cake is 90%, the CST is 59.4, and the solid content is 0.02643gDS / g, the effect of pH on the moisture content and CST of the mud cake shows a trend of first decreasing and then increasing. When the pH value is 6, the moisture content and CST are the lowest, at 47.8% and 10.7. It is speculated that an environment with too low or too high pH may weaken the oxidation efficiency of oxidative free radicals on sludge cells and the dissolution of extracellular polymers, resulting in the deterioration of the sludge dewatering performance.

[0065] Preferably, the flocculated sludge system is filtered using filter press equipment and atmospheric pressure.

[0066] Specifically, when the flocculated sludge system enters the filter press, a closed filter space is formed through the filter plate and filter cloth. Under the pressure of the filter press, the sludge is compressed and the water is squeezed out. At the same time, the atmospheric pressure is used as an auxiliary pressure to act on the sludge and improve the water discharge efficiency. In this way, a mud cake with a lower water content can be obtained, which improves the dehydration efficiency.

[0067] In summary, the enhanced sludge cell disruption and dehydration method based on multi-stage electrochemical coupling sulfite provided in the embodiments of the present application has the following technical effects:

[0068] In the embodiment of the present application, iron is used as the anode and titanium is used as the cathode, an auxiliary oxidizing agent is added to the sludge system to be dehydrated, and the sludge is transferred to the first-stage electrolytic reactor for electrolytic cell breaking and dehydration, wherein the auxiliary oxidizing agent includes sulfite; before the electrode reaches the preset passivation condition, the sludge in the first-stage electrolytic reactor is transferred to the next-stage electrolytic reactor for further electrolytic cell breaking and dehydration; until the electrolysis in the multi-stage electrolytic reactor is completed, a flocculant polydimethyldiallylammonium chloride is added to the sludge system for flocculation, and after flocculation, the flocculated sludge system is filtered using a filter press and atmospheric pressure, the moisture content of the mud cake is measured, and dehydration is completed. The multi-stage electrolysis reactor adopts a three-stage electrolysis reactor, the plate spacing is 2cm, the voltage is 15V, and the three-stage electrochemical pretreatment is carried out according to the reaction time of 10min-10min-10min, the total electrolysis time is 30min, the addition amount of calcium chloride is 74mg / gDS, the addition amount of sodium sulfite is 40mg / gDS, and the addition amount of polydimethyldiallyl ammonium chloride (PDMDAAC) is 10.7mg / gDS. Compared with the method of strengthening the sludge cell breaking and dehydration by long-term monopolar electrochemical treatment, the embodiment of the present application avoids the electrode passivation caused by long-term electrochemical reaction, further improves the dehydration rate of the sludge, reduces the moisture content of the mud cake produced by subsequent filter pressing, and maintains the organic matter content in the mud cake, so as to meet the requirements of sludge self-sustaining incineration.

[0069] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling with sulfite, characterized in that: The method comprises: Using iron as an anode and titanium as a cathode, adding an auxiliary oxidizing agent into the sludge system to be dehydrated, and transferring it to the first-stage electrolytic reactor for electrolytic cell breaking and dehydration, wherein the auxiliary oxidizing agent includes sulfite; Before the electrode reaches the preset passivation condition, the sludge in the first-stage electrolytic reactor is transferred to the next-stage electrolytic reactor for further electrolysis and cell breaking and dehydration; After the electrolysis in the multi-stage electrolysis reactor is completed, a flocculant is added to the sludge system for flocculation, and after flocculation, a filter press is performed to determine the moisture content of the sludge cake to complete dehydration; The multi-stage electrolysis reactor comprises a three-stage electrolysis reactor; The electrolysis cell breaking and dehydration reaction time in the three-stage electrolysis reactor is 10 minutes.

2. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 1, characterized in that: The sulfite is sodium sulfite.

3. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 1, characterized in that: The flocculant is polydimethyldiallylammonium chloride.

4. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 1, characterized in that: The distance between the anode and cathode plates in each electrolysis reactor is 2 cm, and the electrolysis voltage is 15V.

5. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 2, characterized in that: The auxiliary oxidizing agent also includes calcium chloride.

6. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 5, characterized in that: The auxiliary oxidizing agent includes sodium sulfite in an amount of 40 mg / gDS and calcium chloride in an amount of 74 mg / gDS.

7. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 3, characterized in that: The dosage of the polydimethyldiallylammonium chloride is 10.7 mg / g DS.

8. The method for enhancing sludge cell disruption and dehydration based on multi-stage electrochemical coupling sulfite according to claim 1, characterized in that: The flocculated sludge system is filtered using filter press equipment and atmospheric pressure.

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