CN101560040A - Method and device for processing pharmaceutical wastewater by pulse electrocoagulation-MBR - Google Patents

Abstract

A pulse electrocoagulation-MBR method and device for treating pharmaceutical wastewater. The main process is the pulse electrocoagulation-chemical oxidation-MBR process, which sequentially includes a regulating tank, an electrocoagulation reactor, a chemical oxidation tank, an anoxic tank and a membrane biological reaction. The electrocoagulation reactor uses an alternating pulse power supply to provide current, which overcomes the problem of easy passivation of the electrode plate, has the characteristics of low energy consumption and high treatment efficiency, and can remove most of the pollutants in the wastewater; the chemical oxidation pool plays a role of strengthening The role of oxidative decomposition converts refractory substances into biodegradable small molecules; the anoxic pool and membrane bioreactor form the A/O process, and the membrane bioreactor can effectively degrade organic matter and ammonia nitrogen and other pollutants in wastewater. The treated wastewater is filtered out through the membrane, which can meet the industry's first-class A standard. The process is resistant to impact load, the effluent water quality is stable, and the investment cost is low.

Description

A method and device for pulse electrocoagulation-MBR treatment of pharmaceutical wastewater

technical field

The invention belongs to the technical field of water treatment equipment, and relates to a pulse electrocoagulation-MBR method and device for treating pharmaceutical wastewater.

Background technique

Pharmaceutical wastewater pollutants have the characteristics of high content, high concentration of suspended solids, strong toxicity, many refractory substances, large fluctuations in water quality and volume, and complicated treatment. They have always been the focus and difficulty of industrial wastewater treatment. At present, internal electrolysis, coagulation and other physical and chemical methods and biological methods are generally used in the treatment of pharmaceutical wastewater. However, the physical and chemical methods have high energy consumption and large investment, and the biological process is relatively complicated. At the same time, there are long treatment periods, large seasonal influences, and unstable treatment results. And many other features. The complexity of pharmaceutical wastewater and the high consumption and low efficiency of conventional treatment processes are the most direct reasons why a large amount of pharmaceutical wastewater is difficult to treat and discharge up to standard.

Electrocoagulation is a method that relies on the transmission of electric current to make the substrate undergo oxidation-reduction reaction to achieve degradation. It adopts soluble anode (Al or Fe), generates Al ³⁺ , Fe ²⁺ , Fe ³⁺ and other cations on the anode, and at the same time precipitates O ₂ microbubbles on the anode, and generates H ₂ microbubbles on the cathode. The mechanism of electrocoagulation includes electrolytic coagulation, electrolytic air flotation and electrolytic redox. Electrolytic coagulation refers to the hydrolysis and polymerization of cations produced by soluble anodes, which can produce a series of polynuclear hydroxyl complex ions and hydroxides. These substances can be used as flocculants to complex organic polymer substances, suspended pollutants and colloids in water. Flocculation, which removes it from the water. Electrolytic air flotation refers to the generation of a small amount of O ₂ and H ₂ microbubbles during electrolysis of water. The particle size and density of these bubbles are very small, and they have certain adsorption capacity and floating load capacity, which can absorb pollutant flocs produced in water. And float to the water surface, so as to achieve the effect of solid-liquid separation. Electrolytic redox includes two parts, one is that the pollutants directly undergo oxidation-reduction reactions at the anode or cathode, and the other is that the OH free radicals generated during the electrolysis process are extremely oxidizing and react directly with organic pollutants in wastewater without selection. , degraded into carbon dioxide, water and simple organic matter, and the Fe ²⁺ produced by the anode has strong reducibility, which can reduce and degrade some oxidative components in wastewater. The reaction formula of the electrocoagulation process (Fe electrode) is as follows:

Anode: Fe-2e→Fe ²⁺ , 2H ₂ O-4e→O ₂ +4H ⁺ ;

Cathode: 2H ₂ O+2e→H ₂ +2OH ^- ;

In solution: Fe ²⁺ +O ₂ +H ⁺ →Fe ³⁺ +HO ₂ , Fe ²⁺ +HO ₂ +H ⁺ →Fe ³⁺ +H ₂ O ₂ ,

Fe ²⁺ +H ₂ O ₂ →Fe ³⁺ +HO·+OH ^- , Fe ²⁺ +HO·→Fe ³⁺ +OH ^-

Fe ²⁺ +2OH ^- → Fe(OH) ₂ , Fe ³⁺ +3OH ^- → Fe(OH) ₃ ;

At present, the relatively mature application is the direct current electrocoagulation method, but its disadvantages are high energy consumption and easy passivation of the electrodes. Alternating pulse electrocoagulation uses alternating pulse current to energize, and continuously repeats the electrolysis process of "power supply-power-off-power supply". This power supply method greatly improves the electrolysis efficiency and greatly reduces energy consumption. Due to the application of the pulse signal, the reaction on the electrode is intermittent, which is beneficial to the diffusion and reduces the concentration polarization. Since the polarity of the two poles changes frequently, it prevents the electrode from being passivated due to the generation of oxides, improves the efficiency of electrolysis, and is beneficial to the dissolution of soluble electrodes and the stability of effluent water quality.

Membrane bioreactor (MBR) is a device widely used to treat domestic sewage or industrial wastewater. It is composed of a biochemical reactor and a membrane module. The reactor combines efficient membrane separation technology and traditional activated sludge. Craft the merits of both. The sewage treated by activated sludge is filtered by the membrane in the reactor, and the suspended solids and colloids in the water are intercepted. The filtered liquid can be directly discharged up to the standard or entered into the advanced treatment section of the next stage to make it meet the standard of reuse water . At the same time, the high-efficiency interception of the membrane makes the microorganisms completely trapped in the reactor, which is beneficial to the growth and enrichment of nitrifying bacteria and other microorganisms with a long generation time and slow proliferation, and completely solves the problem of sludge loss.

Contents of the invention

The purpose of the present invention is to provide a pulse electrocoagulation-MBR method and device for treating pharmaceutical wastewater. The invention combines pulse electrocoagulation and membrane bioreactor for pharmaceutical wastewater treatment, adopts pulse electrocoagulation-chemical oxidation-MBR main process; alternating pulse electrocoagulation overcomes the passivation and polarization of electrodes, and has energy consumption It has the characteristics of low cost and high treatment efficiency, and can simultaneously play the role of flocculation, air flotation and electrolytic redox, and can remove most pollutants in wastewater; chemical oxidation method uses strong oxidant to convert refractory organic matter in wastewater into biodegradable organic matter, strengthen the oxidation effect; the A/O process is composed of anoxic tank and membrane bioreactor, and the built-in jet aeration device in the membrane bioreactor has high oxygen supply efficiency, which greatly improves the degradation rate of activated sludge on organic matter, which can effectively Degrade the organic matter and ammonia nitrogen and other pollutants in the wastewater, and the treated wastewater is filtered out through the membrane, which can meet the industry's first-class A standard.

The present invention is realized through the following technical solutions:

The process device sequentially includes a regulating tank 1, an electrocoagulation reactor 2, a chemical oxidation tank 3, an anoxic tank 4 and a membrane bioreactor 5; the electrocoagulation reactor 2 includes an electrode plate 6 and an alternating pulse power supply 7, The electrode plate 6 is connected to the alternating pulse power supply 7; the membrane bioreactor 5 includes a built-in membrane module 8 and a jet aeration device 9; it is characterized in that at least one Group electrode plate 6, the anode and the cathode of this electrode plate 6 are all soluble electrodes such as aluminum plate or iron plate, described chemical oxidation tank adds hydrogen peroxide (or sodium hypochlorite, chlorine dioxide, ozone etc.) strong oxidizing agent.

The present invention provides a kind of method that adopts the pulse electrocoagulation-MBR of above-mentioned device to process pharmaceutical waste water, it is characterized in that, this technological method comprises the following steps:

(1) After the wastewater is mixed evenly in the regulating tank, it enters the electroflocculation reactor for electrolysis reaction, and an alternating pulse current is applied on the electrode plate, the current intensity is 1-15A, and the alternating pulse period is 1-20s; during this process , alternating pulse current can overcome the passivation and polarization of the electrode plate, prolong the service life of the electrode plate, reduce energy consumption, and improve the treatment effect;

(2) In the electrocoagulation reactor, the metal ions produced by the soluble anode undergo hydrolysis and polymerization to produce a series of flocculants such as polynuclear hydroxyl complex ions and _hydroxides . H ₂ micro-bubbles are generated on the surface; the flocculant flocculates with high-molecular organic pollutants, suspended solids and toxic substances in the wastewater to form pollutant flocculation groups, and the O ₂ and H ₂ micro-bubbles absorb the pollutants produced in the water and flocculate At the same time, the oxidants such as OH and _O2 produced in the process of wastewater electrolysis can oxidize macromolecular organic matter into small molecular organic matter, improving the biodegradability of wastewater . During this process, most of the organic matter in the wastewater is removed;

(3) After the wastewater is treated by the electrocoagulation reactor, it enters the chemical oxidation tank, and hydrogen peroxide (or sodium hypochlorite, chlorine dioxide, ozone, etc.) is added to the chemical oxidation tank to convert the refractory substances in the wastewater into biodegradable small Molecular organic matter plays the role of strengthening oxidation and decomposition, and then the wastewater enters the A/O process;

(4) The A/O process consists of an anoxic tank and a membrane bioreactor. The jet aeration device built in the membrane bioreactor greatly increases the oxygen content of the mixed liquid in the reactor and enhances the degradation effect on organic matter; After the process treatment, the biodegradability of the wastewater is greatly improved, so the organic pollutants in the wastewater can be effectively removed in this process, and at the same time, the process can also remove pollutants such as ammonia nitrogen and phosphorus in the wastewater;

(6) The wastewater treated by the A/O process is filtered through the membrane, and the membrane filtered water can reach the first-class A standard of the industry;

A pulse electrocoagulation-MBR process for treating pharmaceutical wastewater as described above is characterized in that the alternating pulse current intensity in the electrocoagulation reactor is 1-10A, the alternating pulse period is 1-15s, and the duty cycle is r 0.5~1.0;

Compared with the prior art, the present invention has the following advantages and outstanding effects: simple technological process, convenient maintenance and management, low investment, low energy consumption, impact load resistance, good treatment effect, stable effluent quality, and can reach the industry first-class A The standard is a kind of pharmaceutical wastewater treatment process equipment worthy of being widely promoted and applied in the market.

Description of drawings

Fig. 1 is a schematic flow chart of the pulse electrocoagulation-MBR method for treating pharmaceutical wastewater provided by the present invention.

In the figure: 1-regulation tank; 2-electrocoagulation reactor; 3-chemical oxidation tank; 4-anoxic tank; 5-membrane bioreactor; 6-electrode plate; 7-alternating pulse power supply; 8-membrane module ; 9- jet aeration device.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with technical solutions and drawings.

It can be seen from the schematic diagram of the process flow of the pulse electrocoagulation-MBR method for treating pharmaceutical wastewater that the process device sequentially includes a regulating tank 1, an electrocoagulation reactor 2, a chemical oxidation tank 3, an anoxic tank 4 and a membrane bioreactor 5; The electrocoagulation reactor 2 includes an electrode plate 6 and an alternating pulse power supply 7, and the electrode plate 6 is connected to the alternating pulse power supply 7; the membrane bioreactor 5 includes a built-in membrane module 8 and a jet aeration device 9 It is characterized in that at least one group of electrode plates 6 are arranged in parallel in the described electrocoagulation reactor 2, the anode and cathode of the electrode plates 6 are soluble electrodes such as aluminum plates or iron plates, and hydrogen peroxide is added to the chemical oxidation tank (or sodium hypochlorite, chlorine dioxide, ozone, etc.) strong oxidizing agents.

The present invention provides a kind of method that adopts the pulse electrocoagulation-MBR of above-mentioned device to process pharmaceutical waste water, it is characterized in that, this technological method comprises the following steps:

(1) After the wastewater is mixed evenly in the regulating tank, it enters the electroflocculation reactor for electrolysis reaction, and an alternating pulse current is applied on the electrode plate, the current intensity is 1-15A, and the alternating pulse period is 1-20s; during this process , alternating pulse current can overcome the passivation and polarization of the electrode plate, prolong the service life of the electrode plate, reduce energy consumption, and improve the treatment effect;

(2) In the electrocoagulation reactor, the metal ions produced by the soluble anode undergo hydrolysis and polymerization to produce a series of flocculants such as polynuclear hydroxyl complex ions and _hydroxides . H ₂ micro-bubbles are generated on the surface; the flocculant flocculates with high-molecular organic pollutants, suspended solids and toxic substances in the wastewater to form pollutant flocculation groups, and the O ₂ and H ₂ micro-bubbles absorb the pollutants produced in the water and flocculate At the same time, the oxidants such as OH and _O2 produced in the process of wastewater electrolysis can oxidize macromolecular organic matter into small molecular organic matter, improving the biodegradability of wastewater . During this process, most of the organic matter in the wastewater is removed;

(3) After the wastewater is treated by the electrocoagulation reactor, it enters the chemical oxidation tank, and hydrogen peroxide (or sodium hypochlorite, chlorine dioxide, ozone, etc.) is added to the chemical oxidation tank to convert the refractory substances in the wastewater into biodegradable small Molecular organic matter plays the role of strengthening oxidation and decomposition, and then the wastewater enters the A/O process;

(4) The A/O process consists of an anoxic tank and a membrane bioreactor. The jet aeration device built in the membrane bioreactor greatly increases the oxygen content of the mixed liquid in the reactor and enhances the degradation effect on organic matter; After the process treatment, the biodegradability of the wastewater is greatly improved, so the organic pollutants in the wastewater can be effectively removed in this process, and at the same time, the process can also remove pollutants such as ammonia nitrogen and phosphorus in the wastewater;

(6) The wastewater treated by the A/O process is filtered through the membrane, and the membrane filtered water can reach the first-class A standard of the industry;

In the process of the invention, the alternating pulse current intensity is 1-10A, the alternating pulse period is 1-15s, and the duty ratio r is 0.5-1.0.

Several examples are listed below to illustrate the effects of the present invention, but the scope of the claims of the present invention is not limited thereto.

Example 1: The source of sewage is wastewater from a pharmaceutical factory. The water quality conditions are: CODCr content 17000-20000mg·L-1, BOD content 7000-9000mg·L ^-1 , SS 700mg·L ^-1 , ammonia nitrogen 700mg·L ^-1 . Set the alternating pulse current intensity to 8A, the alternating pulse period to 6s, and the duty ratio r to 0.7. After being treated by pulse electrocoagulation-MBR process, the final effluent COD _Cr is less than 50mg·L ^-1 , the total nitrogen concentration is less than 10mg·L ^-1 , and the turbidity is less than 0.5mg·L ^-1 , reaching the first-class A standard for industrial discharge;

Example 2: The source of sewage is wastewater from a pharmaceutical factory. The water quality conditions are: COD _Cr content 5000～8000mg·L ^-1 , BOD content 2500～10000mg·L ^-1 , SS 500mg·L ^-1 , set alternating pulse current intensity It is 8A, the alternating pulse period is 6s, and the duty ratio r is 0.7. After being treated by the pulse electrocoagulation-MBR process, the COD _Cr of the final effluent is less than 50mg·L ^-1 , and the turbidity is less than 0.5mg·L ^-1 , reaching the first-class A standard for industrial discharge.

Claims (3)

1. A pulse electrocoagulation-MBR process device for treating pharmaceutical wastewater, the process device sequentially includes a regulating tank (1), an electrocoagulation reactor (2), a chemical oxidation tank (3), an anoxic tank (4) and a membrane bioreactor (5); the electrocoagulation reactor (2) includes an electrode plate (6) and an alternating pulse power supply (7), and the electrode plate (6) is connected to an alternating pulse power supply (7); the described The membrane bioreactor (5) includes a built-in membrane module (8) and a jet aeration device (9); it is characterized in that at least one group of electrode plates (6) are arranged in parallel in the electrocoagulation reactor (2) , the anode and cathode of the electrode plate (6) are soluble electrodes such as aluminum plates or iron plates, and the chemical oxidation tank is added with strong oxidizing agents such as hydrogen peroxide (or sodium hypochlorite, chlorine dioxide, ozone, etc.). 2. adopt the processing method of a kind of pulse electrocoagulation-MBR processing pharmaceutical waste water of processing device as claimed in claim 1, it is characterized in that, this processing method comprises the steps: (1) After the wastewater is mixed evenly in the regulating tank, it enters the electroflocculation reactor for electrolysis reaction, and an alternating pulse current is applied on the electrode plate, the current intensity is 1-15A, and the alternating pulse period is 1-20s; during this process , alternating pulse current can overcome the passivation and polarization of the electrode plate, prolong the service life of the electrode plate, reduce energy consumption, and improve the treatment effect; (2) In the electrocoagulation reactor, the metal ions produced by the soluble anode undergo hydrolysis and polymerization to produce a series of flocculants such as polynuclear hydroxyl complex ions and _hydroxides . H ₂ micro-bubbles are generated on the surface; the flocculant flocculates with high-molecular organic pollutants, suspended solids and toxic substances in the wastewater to form pollutant flocculation groups, and the O ₂ and H ₂ micro-bubbles absorb the pollutants produced in the water and flocculate At the same time, the oxidants such as OH and _O2 produced in the process of wastewater electrolysis can oxidize macromolecular organic matter into small molecular organic matter, improving the biodegradability of wastewater . During this process, most of the organic matter in the wastewater is removed; (3) After the wastewater is treated by the electrocoagulation reactor, it enters the chemical oxidation tank, and hydrogen peroxide (or sodium hypochlorite, chlorine dioxide, ozone, etc.) is added to the chemical oxidation tank to convert the refractory and toxic substances in the wastewater into biodegradable ones. The small molecular organic matter plays a role in strengthening oxidation and decomposition, and then the waste water enters the A/O process; (4) The A/O process consists of an anoxic tank and a membrane bioreactor. The jet aeration device built in the membrane bioreactor greatly increases the oxygen content of the mixed liquid in the reactor and enhances the degradation effect on organic matter; After the process treatment, the biodegradability of the wastewater is greatly improved, so the organic pollutants in the wastewater can be effectively removed in this process, and at the same time, the process can also remove pollutants such as ammonia nitrogen and phosphorus in the wastewater; (6) The wastewater treated by the A/O process is filtered through the membrane, and the membrane filtered water can reach the first-class A standard of the industry; 3. A pulse electrocoagulation-MBR process for treating pharmaceutical wastewater according to claim 2, characterized in that the alternating pulse current intensity in the electrocoagulation reactor is 1-10A, and the alternating pulse period is 1-15s , the duty ratio r is 0.5-1.0.

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