CN118878000A - A method for treating and regenerating activated carbon - Google Patents

Abstract

The invention discloses a method for treating and regenerating activated carbon. First, wastewater is passed through an adsorption tank 1 or an adsorption tank 2, so that organic matter in the wastewater is adsorbed on an adsorbent in the adsorption tank, so as to obtain treated water that meets the standards for external discharge or reuse as reclaimed water. When the adsorbent in the adsorption tank 1 or the adsorption tank 2 is saturated with adsorption, another new adsorption tank 1 or the adsorption tank 2 is switched to adsorb and treat the wastewater. At the same time, a sulfuric acid solution is introduced into the adsorption tank 1 or the adsorption tank 2 for analysis. During the analysis, an electrochemical reaction module placed in the adsorption tank is started for electrochemical oxidation analysis. After the oxidation analysis is completed, the sulfuric acid is discharged into a storage tank for use in the next analysis, and then a NaOH solution is introduced to regenerate the adsorbent in the adsorption tank.

Description

A method for treating and regenerating activated carbon

Technical Field

The invention relates to a method for treating and regenerating activated carbon, and belongs to the technical field of wastewater treatment.

Background Art

my country discharges about 71 billion tons of wastewater every year. There are many methods for treating wastewater, including chemical precipitation, microbial treatment, advanced oxidation, electrolysis, adsorption and membrane treatment. Among them, activated carbon adsorption is widely used in wastewater treatment because of its huge surface area and high physical and chemical adsorption functions. It has the characteristics of high efficiency and good effect.

Activated carbon is a porous substance. It mainly purifies wastewater by physical adsorption. Activated carbon adsorption has strong adaptability to wastewater quality, water volume and water temperature, and has broad application prospects. Activated carbon adsorption can remove organic matter, heavy metals, color, odor, etc. in wastewater.

There is an adsorption saturation problem when using activated carbon to treat wastewater. When the activated carbon is saturated with adsorption, it needs to be analyzed. At present, the commonly used analysis processes include variable temperature desorption, decomposition oxidation desorption, chemical desorption and other methods. These desorption methods have some disadvantages. For example, chemical desorption will cause secondary pollution of the desorbent. Other methods also have problems such as low activated carbon regeneration rate.

Summary of the invention

In order to solve the problem that the desorption and regeneration efficiency of activated carbon is low after adsorption saturation in the water treatment process, resulting in the inability to continuously and efficiently treat water, the purpose of the present invention is to provide a water treatment and regeneration method for activated carbon. The method of the present invention uses activated carbon to adsorb and enrich organic matter, and then combines electrochemical oxidation method to analyze and simultaneously treat the adsorption eluate. The method of the present invention can greatly improve the regeneration rate of activated carbon and avoid secondary pollution.

In order to achieve the above object, the present invention adopts the following technical solution:

The present invention discloses a method for treating and regenerating activated carbon in water. The method adopts at least two adsorption tanks, each of which is filled with activated carbon and is also provided with an electrochemical reaction module. Wastewater is firstly adsorbed by the adsorption tank 1 to obtain standard treated water. When the adsorption tank 1 is saturated with adsorption, the wastewater is switched to be adsorbed by the adsorption tank 2, and a sulfuric acid solution is introduced into the adsorption tank 1 for analysis. During the analysis, the electrochemical reaction module placed in the adsorption tank 1 is turned on for electrochemical oxidation analysis. After the electrochemical oxidation analysis is completed, sulfuric acid is discharged. Then, a NaOH solution is introduced into the adsorption tank 1 for regeneration reaction. The NaOH solution is discharged to obtain the adsorption tank 1 containing regenerated activated carbon for adsorption of the next cycle of wastewater.

The water treatment and regeneration method of activated carbon provided by the present invention first uses activated carbon to efficiently adsorb organic matter in wastewater, so that the organic matter can be concentrated and enriched in the activated carbon. Subsequently, through the synergistic effect of sulfuric acid solution and electrochemical reaction module, the organic matter enriched in the activated carbon is electrochemically analyzed and degraded synchronously during the analysis process. After the analysis is completed, the activated carbon is regenerated using NaOH solution to ensure that it has a lasting adsorption capacity, so as to facilitate the recycling of the next round of wastewater treatment. The scheme of the present invention can not only efficiently degrade the concentrated waste liquid analyzed by the activated carbon, but also has a high regeneration rate of the activated carbon.

The inventors discovered that when the electrochemical reaction module is placed in an adsorption tank and the DC power supply of the electrochemical module is turned on during analysis, the activated carbon is polarized under the action of the electrochemical electrodes, with one end becoming the anode and the other end the cathode, forming a micro-electrolyzer. Reduction and oxidation reactions occur at the cathode and anode portions of the electrochemical reaction module, respectively, so that most of the organic matter adsorbed on the activated carbon is decomposed, while a small part is desorbed due to the electrophoretic force; the desorbed organic matter dissolved in the analysis solution is also oxidized and decomposed by the electrochemical electrodes.

In addition, taking the preferred BDD as the anode as an example, the oxygen evolution potential of BDD is high, reaching 2.5-2.8V, and the organic matter degradation and removal rate is higher than other advanced oxidations, almost close to 100%. In addition, during the degradation process of BDD, heat will occur, which is helpful to improve the analysis efficiency of activated carbon. Moreover, during the degradation process of BDD, due to factors such as mass transfer efficiency, the degradation efficiency of low-concentration organic matter is lower than that of low concentration. For example, when COD is 100-500mg/l, the degradation efficiency of BDD is several times or even dozens of times that of 0-100mg/L. Therefore, the present invention uses BDD to treat the concentrated waste liquid analyzed by activated carbon, which greatly improves the efficiency and is more economical. Therefore, the analysis is carried out through the synergistic effect of sulfuric acid solution and BDD reaction module, and then the activated carbon is regenerated with NaOH solution, which has a very high regeneration rate.

In addition, in the present invention, we adopt a one-for-many strategy. When adsorption tank 1 reaches adsorption saturation, it switches to adsorption tank 2 for adsorption. The adsorption tank 1 and the adsorption tank 2 are alternately used in the adsorption, analysis, and degradation processes in different cycles, that is, the two adsorption tanks are responsible for different stages in the adsorption, analysis, and degradation cycles, thereby achieving continuous treatment of wastewater.

The inventors found that in order to achieve high regeneration efficiency of activated carbon, it is crucial to analyze the synergistic effect of sulfuric acid solution and electrochemical reaction module, and then regenerate the activated carbon with NaOH solution. In the process of practical exploration, the inventors also tried to use NaOH solution and electrochemical reaction module for analysis, and then combined with sulfuric acid solution to regenerate the activated carbon, and found that the regeneration efficiency would be greatly reduced.

In a preferred embodiment, the wastewater is organic wastewater with COD≤600 mg/L.

In a preferred embodiment, the activated carbon is selected from at least one of coconut shell activated carbon, fruit shell activated carbon, wood activated carbon and coal activated carbon.

In a preferred solution, the particle size of the activated carbon is 0.2 mm to 5 mm. Controlling the particle size of the activated carbon within this range not only has a good adsorption effect, but also a good regeneration effect, and will not block the pipeline.

In a preferred embodiment, the BDD reaction module contains an anode and a cathode, wherein the anode is selected from at least one of a BDD electrode, a ruthenium-iridium electrode, a graphite electrolysis, and a platinum electrode; preferably, the anode is a BDD electrode, and the cathode is a Ti electrode.

In a preferred embodiment, the anode and cathode in the electrochemical reaction module are inserted into the activated carbon, and the distance between the anode and the cathode is 3-10 cm. The inventors have found that controlling the distance between the anode and the cathode within the scope of the present invention reduces energy consumption and increases efficiency.

In the present invention, the anode and the cathode are inserted into the activated carbon. Under the action of the electrodes, the activated carbon is polarized, one end becomes the anode and the other end becomes the cathode, forming a micro-electrolyzer, which can greatly improve the analysis and degradation effects.

In a preferred embodiment, the concentration of the sulfuric acid solution is 0.5-2 mol/L. In the present invention, the sulfuric acid solution is added in an amount sufficient to completely immerse the activated carbon.

In a preferred embodiment, the sulfuric acid solution is sufficient to completely immerse the activated carbon. If the amount of sulfuric acid solution added is too little, the activated carbon is not completely immersed, which affects the analysis efficiency; if the amount of sulfuric acid solution added is too much, the regeneration efficiency is affected.

In a preferred embodiment, the electrochemical oxidation analysis is powered by a direct current power supply and operated in a constant current mode with a current density of 30-100 mA/cm ₂ and a temperature of ≤70°C.

In a preferred embodiment, the sulfuric acid solution is discharged after the electrochemical oxidation analysis is completed, and the regenerated liquid is directly or after acid supplementation for the next cycle of analysis. In the actual operation process, if the concentration of the discharged sulfuric acid is still within the required range of the present invention, it is directly used for the next cycle of analysis. If the concentration is too low, it is supplemented with acid and then used for the next cycle of analysis.

In a preferred solution, the mass fraction of NaOH in the NaOH solution is 2-3%. The NaOH solution needs to be effectively controlled. If it is too low, the regeneration efficiency will be affected; if it is too high, the pH of the effluent will be affected, wasting the reagent.

The preferred solution is to discharge the NaOH solution into a storage tank for use in the next cycle of analysis.

The process system used in the activated carbon regeneration method of the present invention includes an adsorption tank, a BDD reaction module, a circulation pump, an intermediate water tank, a filter, and also includes pressure, pH, temperature online detection, an electric valve, and a PLC programming automatic control device.

Principles and advantages

The present invention provides a method for water treatment and regeneration of activated carbon. First, the activated carbon is used to efficiently adsorb organic matter in wastewater, so that the organic matter can be concentrated and enriched in the activated carbon. Subsequently, the organic matter enriched in the activated carbon is analyzed and synchronously decomposed through a sulfuric acid solution of a specific concentration and an advanced electrochemical reaction module. This process ensures the continuous improvement of the analysis efficiency through continuous analysis and degradation, while enhancing the regeneration performance and adsorption activity of the active adsorbent. After each round of analysis is completed, the activated carbon is regenerated using a specific NaOH solution to ensure that it has a lasting adsorption capacity to facilitate the recycling of the next round of wastewater treatment.

In the present invention, since the electrochemical reaction module is placed in the adsorption tank, the activated carbon in the adsorption tank is polarized under the action of the electrode, one end becomes the anode, and the other end becomes the cathode, forming a micro-electrolyzer. Reduction reaction and oxidation reaction occur at the cathode and anode parts of the electrochemical reaction module, respectively. Therefore, most of the organic matter adsorbed on the activated carbon is decomposed, and a small part is desorbed by the electrophoretic force; the desorbed organic matter dissolved in the analytical solution will also be oxidized and decomposed by the electrode.

In the present invention, we adopt a strategy of one use and multiple backups. When adsorption tank 1 reaches adsorption saturation, it switches to adsorption tank 2 for adsorption. The adsorption tank 1 and the adsorption tank 2 are alternately used in the adsorption, analysis, and degradation processes in different cycles, that is, the two adsorption tanks are responsible for different stages in the adsorption, analysis, and degradation cycles, thereby achieving continuous treatment of wastewater.

In addition, taking BDD as the anode as an example, the oxygen evolution potential of the BDD electrode is relatively high, reaching 2.5-2.8 V. When treating difficult-to-degrade organic matter, the degradation removal rate of the BDD electrode is better than other advanced oxidation technologies, reaching 99.9%; at the same time, during the BDD degradation process, heat will also occur, further improving the analysis efficiency of activated carbon.

Through the synergistic effect of the process of the present invention, efficient treatment of organic matter in wastewater is achieved, while the number of recycling times of activated carbon is increased, which helps to save resources and reduce the cost of wastewater treatment. In addition, the process effectively avoids the secondary pollution problem caused by the activated carbon desorption process. By adopting the synergistic treatment technology, the process of the present invention can not only efficiently remove organic matter in wastewater, but also ensure that the treatment process is environmentally friendly, economical and sustainable.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a process flow chart of the present invention.

FIG. 2 is a schematic structural diagram of an adsorption tank of the present invention.

DETAILED DESCRIPTION

Example 1

Biochemical effluent from a pesticide factory

The BDD electrode provided in the adsorption tank in this embodiment is a gradient boron-doped silicon-based electrode produced by Xinfeng Technology.

Wastewater (COD concentration of 170mg/L, flow rate of ^10m3 /h) is first filtered and precipitated through a filter, and then passed through an adsorption tank 1 filled with activated carbon (coconut shell activated carbon, particle size of 3mm) to obtain standard treated water for direct discharge. When it is detected that the active agent in the adsorption tank 1 is saturated with adsorption, the pipeline is switched to allow the wastewater filtered by the filter to pass through the adsorption tank 2, while the adsorption tank 1 is introduced with 1mol/L sulfuric acid solution and then the BDD reaction module is opened for oxidation analysis. During the oxidation analysis process, the BDD electrode is used as the anode, the Ti electrode is used as the cathode, the current density is 60mA/ ^cm2 , the reaction temperature is 40-50℃, and the oxidation analysis time is 2.0h. After the oxidation analysis is completed, the obtained post-analysis liquid is passed into a storage tank for temporary storage as a regeneration analysis sulfuric acid solution; then a 2% NaOH solution is passed into the adsorption tank 1 to regenerate the active adsorbent in the adsorption tank 1 for standby use; when the active agent in the adsorption tank 2 is saturated with adsorption, the above operation is repeated for analysis and regeneration; in this way, a cyclic continuous treatment of analysis-degradation is carried out.

Table 1 Pollutant content and activated carbon regeneration after wastewater treatment in Example 1

Example 2

Recycling and evaporation of water from a new energy battery

The BDD electrode provided in the adsorption tank of this embodiment is a gradient boron-doped silicon-based electrode produced by Xinfeng Technology.

The wastewater (COD concentration of 560mg/L, flow rate of ^10m3 /h) is first filtered and precipitated through a filter, and then passed through an adsorption tank 1 filled with activated carbon (50% coconut shell activated carbon, 50% wood activated carbon, particle size of 1-3mm) to obtain standard treated water for direct discharge. When it is detected that the active agent in the adsorption tank 1 is saturated with adsorption, the pipeline is switched to allow the wastewater filtered by the filter to pass through the adsorption tank 2, while the adsorption tank 1 is passed through a 1.5mol/L sulfuric acid solution and then the BDD reaction module is turned on for oxidation analysis. During the oxidation analysis process, the BDD electrode is used as the anode and the Ti electrode is used as the cathode, and the current density is 70mA/ _cm2 , the reaction temperature is 50-60℃, the oxidation analysis time is 4.0h, after the oxidation analysis is completed, the obtained analyzed liquid is passed into the storage tank for temporary storage as the regeneration analysis sulfuric acid solution; then a 2% NaOH solution is passed into the adsorption tank 1 to regenerate the active adsorbent in the adsorption tank 1 for standby use; when the active agent in the adsorption tank 2 is saturated with adsorption, the above operation is repeated for analysis and regeneration; in this way, a continuous analysis-degradation cycle is carried out.

Table 2 Pollutant content and activated carbon regeneration after wastewater treatment in Example 2

Wastewater CODmg/L pH Sulfuric acid analysis liquid COD Activated carbon adsorption capacity Water Intake 560 6.0 Before analysis: 18mg/L Before adsorption: 1141mg/g Water 90 8.4 After analysis: 15mg/L After adsorption: 1200mg/g

Example 3

Activated carbon regeneration rate experiment

The coconut shell activated carbon in Example 1 was subjected to multiple adsorption and oxidation analysis operations, and then the activated carbon adsorption capacity and the COD of the sulfuric acid analysis solution were detected. The results are shown in the following table:

Table 3 Regeneration of activated carbon in multiple cycles

Adsorption times Sulfuric acid analysis liquid CODmg/L Activated carbon adsorption capacity mg/g Activated carbon regeneration rate % Raw water 12mg/L 1330 / 4 15mg/L 1263 95 8 15mg/L 1223 92 12 13mg/L 1170 88

Example 4

Biochemical effluent from a pesticide factory

The ruthenium-iridium electrode is provided in the adsorption tank of this embodiment.

The wastewater (COD concentration of 182mg/L, flow rate of ^10m3 /h) is first filtered and precipitated through a filter, and then passed through an adsorption tank 1 filled with activated carbon (coconut shell activated carbon, particle size of 3mm) to obtain standard treated water for direct discharge. When it is detected that the active agent in the adsorption tank 1 is saturated with adsorption, the pipeline is switched to allow the wastewater filtered by the filter to pass through the adsorption tank 2, while the adsorption tank 1 is passed with 1mol/L sulfuric acid solution and then the ruthenium iridium reaction module is turned on for oxidation analysis. During the oxidation analysis process, the ruthenium iridium electrode is used as the anode, the Ti electrode is used as the cathode, and the current density is 30mA/ ^cm2 , the reaction temperature is 40-50℃, the oxidation analysis time is 2.0h, after the oxidation analysis is completed, the obtained analyzed liquid is passed into the storage tank for temporary storage as the regeneration analysis sulfuric acid solution; then a 2% NaOH solution is passed into the adsorption tank 1 to regenerate the active adsorbent in the adsorption tank 1 for standby use; when the active agent in the adsorption tank 2 is saturated with adsorption, the above operation is repeated for analysis and regeneration; in this way, a continuous analysis-degradation cycle is carried out.

Table 4 Pollutant content and activated carbon regeneration after wastewater treatment in comparative example 2

Claims (10)

1. A method for treating and regenerating activated carbon, characterized in that: at least two adsorption tanks are used, each of which is filled with activated carbon and is also provided with an electrochemical reaction module. Wastewater is first adsorbed by adsorption tank 1 to obtain standard treated water. When adsorption tank 1 is saturated with adsorption, the wastewater is switched to adsorption by adsorption tank 2, and sulfuric acid solution is introduced into adsorption tank 1 for analysis. During the analysis, the electrochemical reaction module placed in adsorption tank 1 is turned on for electrochemical oxidation analysis. After the electrochemical oxidation analysis is completed, sulfuric acid is discharged, and then NaOH solution is introduced into adsorption tank 1 for regeneration reaction. The NaOH solution is discharged to obtain adsorption tank 1 containing regenerated activated carbon for adsorption of the next cycle of wastewater. 2. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that the wastewater is organic wastewater with COD≤600 mg/L. 3. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that: the activated carbon is selected from at least one of coconut shell activated carbon, fruit shell activated carbon, wood activated carbon and coal activated carbon; The particle size of the activated carbon is between 0.2 mm and 5 mm. 4. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that: The electrochemical reaction module contains an anode and a cathode, wherein the anode is selected from at least one of a BDD electrode, a ruthenium-iridium electrode, a graphite electrode, and a platinum electrode; and the cathode is a Ti electrode. 5. A method for water treatment and regeneration of activated carbon according to claim 1 or 4, characterized in that the anode and cathode in the electrochemical reaction module are inserted into the activated carbon, and the distance between the anode and the cathode is 3-10 cm. 6. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that: the concentration of the sulfuric acid solution is 0.5-2 mol/L; The sulfuric acid solution just completely soaks the activated carbon. 7. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that: During the electrochemical oxidation analysis, a DC power supply is used for power supply, and the operation is carried out in a constant current mode, the current density is 30-100 mA/cm ₂ , and the temperature of the electrochemical oxidation analysis is ≤70°C. 8. A method for water treatment and regeneration of activated carbon according to claim 1 or 7, characterized in that: after the electrochemical oxidation analysis is completed, the sulfuric acid solution is discharged, and the regenerated liquid is obtained directly or after acid supplementation for the next cycle of analysis. 9. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that the mass fraction of NaOH in the NaOH solution is 2-3%. 10. The method for water treatment and regeneration of activated carbon according to claim 1, characterized in that: The NaOH solution is discharged into a storage tank for analysis in the next cycle.