CN102502946A - Method for treating chemical wastewater by utilizing three-dimensional electrode-biological membrane process - Google Patents

Abstract

The invention discloses a method for treating chemical wastewater by using a three-dimensional electrode-biofilm process, which is carried out according to the following steps: (1) placing activated carbon in a membrane bioreaction tank of activated sludge for uninterrupted aeration; (2) Use Ti/ _PbO2 plate as positive electrode, stainless steel plate as negative electrode and bind activated carbon fiber layer on its surface, and activated carbon as the third electrode; (3) Add activated sludge to the reaction vessel, and add culture medium to activate carbon fiber layer. (4) Enter the waste water to be treated into the reaction vessel through the water inlet in an upflow manner, and control the current density and hydraulic retention time at the same time to achieve continuous operation of the reactor and better treatment effect. The invention provides a sewage treatment process combining an electrochemical method and a biofilm method, which has the characteristics of high mass transfer efficiency, large reaction area, high treatment efficiency and easy operation.

Description

A method for treating chemical wastewater by using three-dimensional electrode-biofilm process

technical field

The invention relates to a sewage treatment method, more specifically, relates to a waste water treatment method utilizing a combination of a three-dimensional electrode and a biofilm.

Background technique

With the development of economy and society, the shortage of water resources has become a common challenge faced by the whole world. Facing this problem, many countries regard the recycling of sewage as one of the important means to solve the shortage of water resources. For a long time, the traditional biological treatment process represented by activated sludge has been widely used in the treatment of domestic sewage and industrial wastewater. It has the advantages of perfect treatment process and stable treatment effect. However, there are also problems such as large land occupation, large infrastructure investment, and large amounts of excess sludge. Industrial wastewater contains a large number of highly toxic, high-concentration, and biodegradable substances that are difficult to remove by traditional secondary treatment processes. As a result, the biochemical effluent of sewage treatment plants still contains a certain concentration of toxic and harmful substances, which is harmful to the water environment. It has caused great harm to the survival of human beings and urgently needs in-depth treatment.

In order to overcome these problems, various new and efficient sewage treatment technologies have emerged, especially the membrane bioreactor (Membrane bioreactor, MBR) technology that combines membrane separation technology and biological treatment process, because it replaces traditional biological treatment process. The secondary settling tank in the plant realizes high sludge concentration operation, and has the advantages of good effluent water quality, simple operation and maintenance, small footprint, high sludge concentration, and low residual sludge output. It is widely used in the field of wastewater treatment. Although MBR technology has many advantages that traditional activated sludge method does not have. However, its high energy consumption and high cost are still two bottlenecks hindering the development of MBR. The high membrane price and the cleaning and replacement of membrane components caused by frequent membrane fouling are the main reasons for the high operating cost of MBR. However, the shortened membrane service life, frequent chemical cleaning, decreased membrane flux, and increased operating costs caused by membrane fouling have greatly limited the promotion and application of MBR technology.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a sewage treatment process combining electrochemical method and biofilm method, which has the characteristics of high mass transfer efficiency, large reaction area, high treatment efficiency and easy operation.

The purpose of the present invention is achieved through the following technical solutions:

A method for treating chemical waste water by using a three-dimensional electrode-biofilm process is carried out according to the following steps:

(1) Put the activated carbon in the membrane bioreaction tank with an activated sludge concentration of 3000-4000mg/L, and carry out uninterrupted aeration, and the activated carbon stays in the reaction tank for at least 72 hours

(2) Use the Ti/ _PbO2 plate as the positive electrode, use the stainless steel plate as the negative electrode and bind the activated carbon fiber layer on its surface, and use the activated carbon treated in step (1) as the third electrode

(3) Add activated sludge to the reaction vessel, and add culture medium to cultivate biofilm on activated carbon

(4) Enter the waste water to be treated into the reaction vessel through the water inlet in an upflow manner, and control the current density and hydraulic retention time at the same time to achieve continuous operation of the reactor and better treatment effect

The reaction vessel used in the technical solution of the present invention is a three-dimensional electrode-biofilm reactor, including a power supply, an anode, a cathode, activated carbon biofilm and a reactor body, wherein:

The bottom of the reactor body 11 is provided with a water inlet 10 and a slag outlet 9, and the top is provided with a water outlet 8;

The reactor body 11 is provided with a partition 12, and the partition 12 is provided with a plate socket and uniform water distribution holes;

The anode 5 and the cathode 6 are respectively arranged in the plate socket of the separator 12, and are respectively connected to the positive pole and the negative pole of the power supply;

An activated carbon fiber layer is arranged on the cathode;

An activated carbon biofilm layer 7 is arranged between the anode and the cathode.

The anode can be a Ti/PbO ₂ plate.

The cathode can be made of stainless steel.

The power supply is preferably a steady-voltage and constant-current power supply.

In the technical solution of the present invention, the particle size of the activated carbon is preferably 2-3mm, and the residence time of the activated carbon in the reaction tank in the step (1) is 72-120 hours. In the step (2), the thickness of the activated carbon fiber layer is 4-6mm, and the size of the electrode plate is preferably 10cm×10cm. In the step (3), the activated sludge with a concentration of 100mg/L is added to the three-dimensional electrode reactor, according to the ratio of molar ratio C:N:P=100:5:1, every two days into the reactor Add 3.12g of glucose, 0.079g of ammonium bicarbonate, 0.027g of potassium dihydrogenphosphate, 0.04g of calcium chloride, 0.024g of magnesium sulfate, 0.056g of iron sulfate, 0.004g of zinc sulfate and 0.003g of copper sulfate to realize the addition of activated carbon The purpose of cultivating biofilm; when in use, first fix the anode and cathode in the plate socket on the separator, and then put activated carbon between the two electrodes as the third pole, and carry out biofilm cultivation. In the step (4), the current density is controlled at 0.125mA/cm ² -1.0mA/cm ² , and the hydraulic retention time is generally controlled at 2.5-3h.

At present, physical and chemical means are mostly used in advanced sewage treatment technologies. Physical means mainly include coagulation sedimentation, membrane filtration, adsorption method, advanced oxidation technology such as Fenton method, ozone, photocatalytic oxidation, wet oxidation, and electrochemical method. The electrochemical method mainly uses substances such as OH and Cl ₂ produced by electrode reactions to directly oxidize and indirectly oxidize toxic and harmful substances in water. The three-dimensional electrode, also known as the particle electrode, is a new type of electrochemical reactor. The granular working electrode material is filled between the electrodes of the traditional two-dimensional electrolyzer, and charged to become the third electrode, and participate in the removal of organic pollutants. The removal reaction has the characteristics of high mass transfer efficiency, large reaction area, high processing efficiency and easy operation. According to the technical scheme of the present invention, the third pole activated carbon in the traditional three-dimensional electrode is first put into the activated sludge for a period of soaking, then taken out and put back into the reactor, and glucose is added to the reactor for cultivation, so that the activated carbon The activated carbon biofilm layer is formed by attaching and growing biofilm on the surface, which is used to further treat the wastewater after electrolysis. In addition, activated carbon can also be used as a catalyst to make the hydrogen peroxide produced in the electrolysis process generate more hydroxyl radicals and remove organic matter.

During sewage treatment, the influent water is poured into the reactor from the bottom of the reactor through the constant flow pump 2 from the water storage tank 1, and the water flow direction is an upflow type. After passing through the separator, it enters the activated carbon biofilm between the anode and the cathode. In the layer, a small amount of current is passed through, and the organic matter in the waste water is decomposed by the microorganisms that grow freely on the third pole, and the secondary effluent that does not meet the standard in the chemical production is treated to a better degree, so that it COD _Cr reaches the national emission standard.

The present invention has the following characteristics: (1) the reactor combines the two major wastewater treatment processes of electrochemical method and biological method, which reduces the content of organic matter in the water to the greatest extent; (2) the reactor utilizes biofilm to improve biochemical (3) The biofilm in the reactor is the free growth of microorganisms on the surface of the third pole activated carbon, and no special inoculation work is required , easy to operate, easy to operate and maintain.

Description of drawings

Fig. 1 is the flow chart that utilizes the technical solution of the invention to carry out sewage treatment, wherein 1 storage tank, 2 constant flow pumps, 3, valves, 4 steady voltage and steady current power supplies, 5 anodes, 6 cathodes, 7 activated carbon biofilms, 8 water outlets , 9 slag outlet, 10 water inlet.

Fig. 2 is a schematic diagram of the structure of the three-dimensional electrode-biofilm reactor used in the present invention, wherein 11 is the reactor body, and 12 is the separator.

Fig. 3 is a schematic structural view of the cathode in the three-dimensional electrode-biofilm reactor used in the present invention (the cathode is made of stainless steel).

Fig. 4 is a structural schematic diagram of the separator in the three-dimensional electrode-biofilm reactor used in the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments. A three-dimensional electrode-biofilm reactor used in the present invention includes a power supply, an anode, a cathode, an activated carbon biofilm and a reactor body, wherein: the bottom end of the reactor body 11 is provided with a water inlet 10 and a slag discharge port 9 , the top is provided with a water outlet 8; the reactor body 11 is provided with a partition 12, and the partition 12 is provided with a plate socket and a uniform water distribution hole; the anode 5 and the cathode 6 are respectively arranged on the partition 12 in the plate socket, and respectively connected to the positive pole and the negative pole of the power supply; an activated carbon fiber layer is arranged on the cathode; an activated carbon biofilm layer 7 is arranged between the anode and the cathode. Specifically,

(1) Put the activated carbon in the membrane bioreaction tank with an activated sludge concentration of 3000-4000mg/L, and carry out uninterrupted aeration, and the activated carbon stays in the reaction tank for 72-120 hours

(2) In the reaction vessel, the Ti/ _PbO2 plate is used as the positive electrode, the stainless steel plate is used as the negative electrode, and an activated carbon fiber layer is bound on its surface, with a thickness of 4-6mm. The size of the electrode plates is 10cm×10cm, and the activated carbon is used as the The third pole, the particle size of activated carbon is 2-3mm, and the above three electrodes together form a three-dimensional electrode

(3) Adding activated sludge with a concentration of 100mg/L to the three-dimensional electrode reactor, according to the ratio of molar ratio C:N:P=100:5:1, adding 3.12g of glucose and carbonic acid to the reactor every two days Ammonium hydrogen 0.079g, potassium dihydrogen phosphate 0.027g, calcium chloride 0.04g, magnesium sulfate 0.024g, iron sulfate 0.056g, zinc sulfate 0.004g and copper sulfate 0.003g cultivate biofilm.

(4) Pump chemical waste water into the biofilm-three-dimensional electrode reactor through the water inlet in an upflow manner, and carry out sewage treatment as follows:

Example 1

The COD _Cr range of the raw water is 60-85mg/L, the Cl ^- concentration range is 1500-2000mg/L, the BOD ₅ range is 1-9mg/L, the conductivity range is 7500-8500μS/cm, and the influent pH range is 8.4-8.8. The raw water was injected into the three-dimensional electrode-biofilm reactor in an upflow mode, and the current density of the three-microelectrode-biofilm reactor was adjusted to 0.125mA/cm ² , 0.25mA/cm ² , 0.5mA/cm ² and 1.0mA/cm 2 cm ² , designed according to the residence time of 3 hours. After long-term operation, the treatment effect is shown in Table 1.

Table 1 Operation effect of three-dimensional electrode-biofilm reactor

Current density (mA/cm ² ) 0.125 0.25 0.5 1.0 COD _Cr removal rate (%) 19% 25% 35% 55%

Example 2

The reactor will convert Cl ^- into Cl ₂ during the electrolysis of wastewater, which will have adverse effects on the growth of microorganisms. By changing the current density to 0.125mA/cm ² , 0.25mA/cm ² , 0.5mA/cm ² , and 1.0mA/cm ² , the microbial biomass on the third-pole activated carbon showed a trend of first increasing and then decreasing. Among them, the current When the density is 0.5mA/ ^cm2 , the amount of biofilm in the reactor is the largest, reaching 120-130mgCOD/g activated carbon.

Example 3

Since this reactor produces H ⁺ in the process of electrolyzing wastewater, it will increase the H ⁺ concentration of the raw water. By adjusting the current density to 0.125mA/cm ² , 0.25mA/cm ² , 0.5mA/cm ² , 1.0mA /cm ² , it can be seen that the pH value has been decreasing. When the current density is 0.5mA/cm ² , the pH of the wastewater is close to neutral.

Under the condition of the current density of 0.5mA/ ^cm2 , the COD _Cr value of the three-dimensional electrode-biofilm reactor effluent is slightly higher than 40mg/L, and the treatment effect is good enough, basically reaching the national first-class B standard, and the amount of biofilm Relatively stable, so 0.5mA/cm ₂ is a more suitable operating condition.

The invention has been described as an example above. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacements that can be made by those skilled in the art without creative labor all fall within the scope of this invention. protection scope of the invention.

Claims (5)

1. A method utilizing three-dimensional electrode-biofilm technology to process chemical waste water, is characterized in that, carries out according to the following steps: (1) Put the activated carbon in the membrane bioreaction tank with an activated sludge concentration of 3000-4000mg/L, and carry out uninterrupted aeration, and the activated carbon stays in the reaction tank for at least 72 hours (2) Use the Ti/ _PbO2 plate as the positive electrode, use the stainless steel plate as the negative electrode and bind the activated carbon fiber layer on its surface, and use the activated carbon treated in step (1) as the third electrode (3) Add activated sludge to the reaction vessel, and add culture medium to cultivate biofilm on activated carbon (4) Enter the waste water to be treated into the reaction vessel through the water inlet in an upflow manner, and control the current density and hydraulic retention time at the same time to achieve continuous operation of the reactor and better treatment effect Wherein said reaction vessel is a three-dimensional electrode-biofilm reactor, including power supply, anode, cathode, activated carbon biofilm and reactor body, wherein: The bottom of the reactor body is provided with a water inlet and a slag outlet, and the top is provided with a water outlet; The reactor body is provided with a partition, and the partition is provided with a plate socket and uniform water distribution holes; The anode and the cathode are respectively arranged in the plate socket of the separator, and are respectively connected to the positive pole and the negative pole of the power supply; an activated carbon biofilm layer is arranged between the anode and the cathode. 2. a kind of method utilizing three-dimensional electrode-biofilm technology to process chemical wastewater according to claim 1, is characterized in that, the preferred 2-3mm of the particle diameter of described activated carbon, activated carbon is in reaction tank in described step (1). Medium residence time is 72-120 hours. 3. a kind of method utilizing three-dimensional electrode-biofilm technology to process chemical wastewater according to claim 1, is characterized in that, in described step (2), the thickness of described activated carbon fiber layer is 4-6mm, and electrode plate The size is preferably 10cm×10cm. 4. a kind of method utilizing three-dimensional electrode-biofilm technology to process chemical wastewater according to claim 1, is characterized in that, in described step (3), in three-dimensional electrode reactor, adding concentration is 100mg/L Activated sludge, according to the ratio of molar ratio C:N:P=100:5:1, add glucose 3.12g, ammonium bicarbonate 0.079g, potassium dihydrogen phosphate 0.027g, calcium chloride 0.04 to the reactor every two days g, magnesium sulfate 0.024g, iron sulfate 0.056g, zinc sulfate 0.004g and copper sulfate 0.003g, to realize the purpose of cultivating biofilm on the activated carbon added. 5. A method for treating chemical wastewater using a three-dimensional electrode-biofilm process according to claim 1, characterized in that, in the step (4), the current density is controlled at 0.125mA/cm ² -1.0mA/cm ^2. The hydraulic retention time is generally controlled at 2.5-3h.

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