CN108298725A - A kind of batch-type Fenton oxidation reactor reagent adds course control method for use - Google Patents

Abstract

The invention discloses a method for controlling the reagent dosing process of a sequencing batch type Fenton oxidation reactor. The control method is realized according to the following steps: selecting the effluent of a refractory industrial wastewater biochemical treatment system as the industrial wastewater to be treated; constructing the Fenton reagent dosing method Process automatic control system; run the sequence batch type Fenton oxidation reactor, set the operating parameters; use the Fenton reagent dosing process automatic control system to control the sequence batch type Fenton oxidation reactor Fenton reagent dosing process, so that the sequence batch type Fenton oxidation reactor Batch Fenton Oxidation Reactor reaches steady state. The Fenton reagent dosing process control method of the sequence batch type Fenton oxidation reaction method of the present invention takes the oxidation-reduction potential ORP in the sequence batch type Fenton oxidation reactor as a control variable, adopts a feedback control structure, and regulates the hydrogen peroxide dosing and metering The operation of the pump and the ferrous sulfate dosing metering pump can control the Fenton reagent dosing process, which can avoid the influence of too high or too low Fenton reagent dosage on the oxidation effect, sludge output, subsequent treatment, etc.

Description

A method for controlling the reagent dosing process of a sequencing batch type Fenton oxidation reactor

technical field

The invention relates to the operation control of the Fenton oxidation reaction method, in particular to the Fenton reagent dosing process control method of the sequential batch Fenton oxidation reaction method.

Background technique

A large number of engineering practices have proved that for some refractory organic wastewater after pre-treatment, there are still a small amount of organic matter in the water. At this time, the water quality still cannot meet the discharge requirements, and advanced treatment is required to make the effluent water quality achieve the expected effect.

Fenton oxidation has a history of 100 years since it was discovered by French scientist Fenton in 1894. As an effective advanced oxidation process, due to its simple equipment, strong oxidation ability and high treatment efficiency, it is widely used in advanced treatment of various difficult Degradation of industrial wastewater. The reason why Fenton’s reagent has a very strong oxidizing ability is mainly because Fe ²⁺ reacts with H ₂ O ₂ under acidic conditions to generate a large number of hydroxyl radicals with strong oxidizing ability. The free radicals have the following characteristics: ①Extreme oxidizing ability Strong, compared with general oxidants, hydroxyl radicals have a higher standard electrode potential, second only to elemental fluorine, and are extremely strong oxidants that can react with a variety of organic substances; The reaction involved is the chemical reaction of free radicals, so the chemical reaction is extremely fast, and the reaction rate constant is 7 orders of magnitude higher than that of the ozone oxidation reaction, which greatly shortens the time for wastewater treatment; ③The electronegativity is extremely high, and the electron affinity of hydroxyl radicals The power is as high as 569.3KJ, and it will preferentially attack the parts with high electron cloud density in organic matter. After the reaction of hydroxyl radicals to oxidize organic substances, add lye to neutralize, and use the colloidal adsorption and flocculation of Fe(OH) ₃ to further remove organic substances in water.

From the Fenton reaction mechanism, it can be seen that the key to the Fenton oxidation reaction is hydroxyl radicals, so the dosage of Fe ²⁺ and H ₂ O ₂ has a great influence on the advanced treatment effect of refractory industrial wastewater. When the dosage of Fe ²⁺ and H ₂ O ₂ is low, the generation of hydroxyl radicals is relatively small, and the treatment efficiency is low. However, H ₂ O ₂ is also a hydroxyl radical scavenger at the same time. If the dosage of H ₂ O ₂ is too high, it will capture the hydroxyl radicals generated by the system. When the dosage of iron is too high, H ₂ O ₂ is rapidly catalyzed and decomposed to produce a large number of active hydroxyl radicals, but the reaction speed of hydroxyl radicals with the substrate is relatively slow, so the unconsumed free hydroxyl radicals interact with each other The quenching reaction produces water, which causes some of the hydroxyl radicals to be consumed, thereby reducing the treatment efficiency of the hydroxyl radicals. At the same time, too high iron dosage will increase the chroma of the treated water and increase the sludge output. In addition, the cost of Fe ²⁺ and H ₂ O ₂ reagents is relatively high. In addition, refractory industrial wastewater has great changes in the types, concentrations, and water volumes of pollutants, and the fixed Fenton reagent dosage cannot adapt to changes in water quality to ensure the effective completion of advanced treatment requirements for refractory organic industrial wastewater. Therefore, it is necessary to Monitor and control the chemical dosing process of the Fenton oxidation reaction.

Contents of the invention

The purpose of the present invention is to provide a kind of Fenton reagent dosing process control method of sequential batch type Fenton oxidation reaction method, can monitor and control the medicament dosing process of Fenton oxidation reaction in real time, avoid Fenton reagent dosage The influence of too high or too low on oxidation effect, sludge output, subsequent treatment, etc.

To achieve the above object, the present invention provides the following scheme:

A kind of sequential batch type Fenton oxidation reactor reagent dosing process control method, described control method is realized according to the following steps:

Step 1: Select the effluent from the refractory industrial wastewater biochemical treatment system as the industrial wastewater to be treated, the wastewater volume is 50-100m ³ /d, the COD concentration is 50-100mg/L, the ammonia nitrogen concentration is 10-30mg/L, Suspended solid SS concentration is 70-100mg/L;

Step 2: Build an automatic control system for the Fenton reagent dosing process, the automatic control system for the Fenton reagent dosing process includes a ferrous sulfate storage solution deployment pool, a hydrogen peroxide storage pool, a sequencing batch Fenton oxidation reactor, Redox potential ORP online detector, computer with PLC controller installed, ferrous sulfate dosing metering pump, hydrogen peroxide dosing metering pump and metering pump controller; The bottom 20cm of the Oxidation Reactor, the middle depth, and 20cm below the water surface; the automatic control system of the Fenton reagent dosing process adopts the control parameter ORP setting value strategy: during the initial addition of Fenton reagent in the oxidation reaction process The ORP online detector in the batch-type Fenton oxidation reactor can measure the ORP value in the batch-type Fenton oxidation reactor in real time and continuously online. The computer data acquisition card collects and stores the value every 30s, and calculates the average value. The value is converted into a digital signal and input to the PLC controller; compared with the ORP set value of 450-500mV, the PID algorithm is used to calculate and output the digital signal calculation result, and the digital signal calculation result is converted into an analog signal and used as a metering pump control The metering pump controller controls the ferrous sulfate dosing metering pump and the hydrogen peroxide dosing metering pump to close, and stops adding the Fenton reagent;

Step 3: Run the sequencing batch Fenton oxidation reactor, which includes 6 processes: water intake, pH adjustment, Fenton oxidation reaction, flocculation, sedimentation, drainage and sludge discharge, and the operating parameters are set as follows: hydraulic retention The time is 4-8h, the number of reactor groups is 1-3 groups, and each group of reactors operates 2-4 cycles per day; during each cycle of operation, the effluent of the biochemical pool stored in the regulating tank enters the sequence batch Fenton oxidation reaction In the reactor, the time of the water inlet process is 10-30min; after the water inlet process is completed, acid solution is added to the reactor, and the pH value in the reactor is adjusted to be 3-5, and the pH value adjustment process is entered, and the pH value adjustment process time is 5-10min, using mechanical stirring, the stirring speed gradient is 720-900s ^-1 ; The dosage of the Fenton reagent is regulated by the automatic control system of the Fenton reagent dosing process described in step 2. The mechanical stirring method is adopted. The stirring speed gradient is 720-900s ^-1 in the initial 10-30min of the process, and the stirring speed gradient is 240s in the remaining time. -300s ^-1 ; After the Fenton oxidation reaction process is finished, add lye to the reactor to adjust the pH value to 7-8, enter the flocculation process, the time is 20-40min, adopt mechanical stirring method, stir in the initial 5-10min The speed gradient is 720-900s ^-1 , and the stirring speed gradient is 20-60s ^-1 in the remaining time; after the flocculation process is completed, it enters the sedimentation process for 0.5h, and finally the drainage and sludge discharge process for 1-1.5h;

Step 4: The Fenton reagent dosing process automatic control system described in step 2 is used to control the Fenton reagent dosing process of the sequencing batch type Fenton oxidation reactor, so that the sequencing batch type Fenton oxidation reactor reaches a stable working condition.

Optionally, the concentration of the ferrous sulfate stock solution in step 2 is 22.67g/L, and the feeding flow of ferrous sulfate stock solution per cycle of each group of reactors is 35-135L/min; the hydrogen peroxide stock solution in step 2 The concentration is 330g/L, and the hydrogen peroxide dosing flow rate per cycle of each group of reactors is 0.2-2.5L/min.

Optionally, the ORP setting value of the PLC controller in step 2 is 475mV.

Optionally, the hydraulic retention time of the sequencing batch Fenton oxidation reactor in step 3 is 8h.

Optionally, the number of groups of sequencing batch Fenton oxidation reactors in step 3 is 2 groups.

Optionally, the sequencing batch Fenton oxidation reactor in step 3 runs 3 cycles per day.

Optionally, in step 2, the dosing flow rate of ferrous sulfate stock solution per cycle for each group of reactors is 90 L/min, and the dosing flow rate of hydrogen peroxide for each group of reactors is 1.75 L/min per cycle.

According to the specific embodiments provided by the invention, the invention discloses the following technical effects:

The Fenton reagent dosing process control method of the sequence batch type Fenton oxidation reaction method of the present invention uses the ORP in the sequence batch type Fenton oxidation reactor as a control variable, adopts a feedback control structure, and regulates the hydrogen peroxide dosing metering pump and The operation of the ferrous sulfate dosing metering pump and the control of the Fenton reagent dosing process can avoid the impact of excessive or low Fenton reagent dosage on the oxidation effect, sludge output, and subsequent treatment.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without paying creative labor.

FIG. 1 is a flow chart of a control method provided in Embodiment 1 of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The object of the present invention is to provide a kind of Fenton's reagent dosing process control method of sequence batch type Fenton oxidation reaction method, with the ORP (Oxidation-Reduction Potential, redox potential) in the sequence batch type Fenton oxidation reactor as control Variable, adopts feedback control structure, regulates the operation of hydrogen peroxide dosing metering pump and ferrous sulfate dosing metering pump, controls the Fenton reagent dosing process, and can avoid the effect of excessive or low Fenton reagent dosage on the oxidation effect , sludge production, subsequent treatment, etc.

Oxidation-reduction potential (ORP) is an important factor that determines the direction and degree of oxidation-reduction reactions. The redox potential reflects the comprehensive redox ability of a system. From a microscopic point of view, in a certain system, each substance has its unique redox ability, and different substances will react and influence each other, and finally show a certain ORP on a macroscopic level. In aqueous solution, ORP is a complex system composed of multiple redox couples. Therefore, although ORP cannot fully express the concentration of a certain oxide or reducing substance, it can reflect the relative degree of oxidation or reduction of a certain system. Fenton oxidation technology is an advanced wastewater treatment technology that has been popularized and applied in recent years, and its reaction essence is an oxidation-reduction reaction. In the Fenton oxidation reactor, the hydroxyl radicals generated by Fe ²⁺ and H ₂ O ₂ under acidic conditions are the main oxidizing substances, and the main reducing substances are refractory organic substances and Fe ²⁺ in wastewater, The concentration changes of the above-mentioned substances affect the ORP value. After adding Fe ²⁺ and H ₂ O ₂ to the sequencing batch Fenton oxidation reaction system, because the two generate strong oxidizing substance hydroxyl radicals, the reaction rate is relatively high, so the concentration of hydroxyl radicals increases rapidly, according to Nernst According to the equation, the ORP value in the reactor will also rise rapidly and reach the maximum value, and the maximum ORP value in the reactor is positively correlated with the initial H ₂ O ₂ dosage. In addition, the results of experimental research and engineering practice show that there is an optimal initial dosage of hydrogen peroxide in the Fenton oxidation system. To sum up, the change rule of ORP value in the sequencing batch Fenton oxidation reaction system can reflect the amount of hydrogen peroxide added, so it can be used as a control parameter to regulate the process of Fenton reagent addition.

In addition, ORP has the advantages of easy on-line detection, short response time, and high precision. Therefore, the present invention provides a set of Fenton reagent dosing process control system for sequential batch Fenton oxidation reactors with ORP as the control variable. , in order to achieve the removal efficiency of refractory organic substances and easier process operation control and management.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1: FIG. 1 is a flowchart of a control method provided in Embodiment 1 of the present invention. As shown in Figure 1, the reagent dosing process control method for the sequencing batch type Fenton oxidation reactor provided by this embodiment comprises the following steps:

Step 1: Select the effluent from the refractory industrial wastewater biochemical treatment system as the industrial wastewater to be treated, the wastewater volume is 50-100m ³ /d, the COD concentration is 50-100mg/L, the ammonia nitrogen concentration is 10-30mg/L, Suspended solid SS concentration is 70-100mg/L.

Step 2: Build an automatic control system for the Fenton reagent dosing process, the automatic control system for the Fenton reagent dosing process includes a ferrous sulfate storage solution deployment pool, a hydrogen peroxide storage pool, a sequencing batch Fenton oxidation reactor, Redox potential ORP online detector, computer with PLC controller installed, ferrous sulfate dosing metering pump, hydrogen peroxide dosing metering pump and metering pump controller; The bottom 20cm of the Oxidation Reactor, the middle depth, and 20cm below the water surface; the automatic control system of the Fenton reagent dosing process adopts the control parameter ORP setting value strategy: during the initial addition of Fenton reagent in the oxidation reaction process The ORP online detector in the batch-type Fenton oxidation reactor can measure the ORP value in the batch-type Fenton oxidation reactor in real time and continuously online. The computer data acquisition card collects and stores the value every 30s, and calculates the average value. The value is converted into a digital signal and input to the PLC controller; compared with the ORP set value of 450-500mV, the PID algorithm is used to calculate and output the digital signal calculation result, and the digital signal calculation result is converted into an analog signal and used as a metering pump control The metering pump controller controls the ferrous sulfate dosing metering pump and the hydrogen peroxide dosing metering pump to shut down, and stops adding Fenton’s reagent.

Step 3: Run the sequencing batch Fenton oxidation reactor, which includes 6 processes: water intake, pH adjustment, Fenton oxidation reaction, flocculation, sedimentation, drainage and sludge discharge, and the operating parameters are set as follows: hydraulic retention The time is 4-8h, the number of reactor groups is 1-3 groups, and each group of reactors operates 2-4 cycles per day; during each cycle of operation, the effluent of the biochemical pool stored in the regulating tank enters the sequence batch Fenton oxidation reaction In the reactor, the time of the water inlet process is 10-30min; after the water inlet process is completed, acid solution is added to the reactor, and the pH value in the reactor is adjusted to be 3-5, and the pH value adjustment process is entered, and the pH value adjustment process time is 5-10min, using mechanical stirring, the stirring speed gradient is 720-900s ^-1 ; The dosage of the Fenton reagent is regulated by the automatic control system of the Fenton reagent dosing process described in step 2. The mechanical stirring method is adopted. The stirring speed gradient is 720-900s ^-1 in the initial 10-30min of the process, and the stirring speed gradient is 240s in the remaining time. -300s ^-1 ; After the Fenton oxidation reaction process is finished, add lye to the reactor to adjust the pH value to 7-8, enter the flocculation process, the time is 20-40min, adopt mechanical stirring method, stir in the initial 5-10min The speed gradient is 720-900s ^-1 , and the stirring speed gradient is 20-60s ^-1 in the remaining time; after the flocculation process, it enters the sedimentation process for 0.5h, and finally the drainage and sludge discharge process for 1-1.5h.

Step 4: The Fenton reagent dosing process automatic control system described in step 2 is used to control the Fenton reagent dosing process of the sequencing batch type Fenton oxidation reactor, so that the sequencing batch type Fenton oxidation reactor reaches a stable working condition.

Preferably, the ferrous sulfate stock solution concentration in step 2 is 22.67g/L, and the per cycle ferrous sulfate stock solution dosing flow rate of each group of reactors is 35-135L/min; the concentration of hydrogen peroxide stock solution in step 2 It is 330g/L, and the hydrogen peroxide dosing flow rate per cycle of each group of reactors is 0.2-2.5L/min.

Embodiment 2: This embodiment differs from Embodiment 1 in that the ORP setting value of the PLC controller in step 2 is 475 mV, and the others are the same as Embodiment 1.

Embodiment 3. The difference between this embodiment and Embodiment 1 or 2 is that the hydraulic retention time of the sequencing batch Fenton oxidation reactor in step 3 is 8h, and the others are the same as Embodiment 1 or 2.

Embodiment 4. The difference between this embodiment and Embodiments 1 to 3 is that the number of sequencing batch Fenton oxidation reactors in step 3 is 2, and the others are the same as Embodiments 1 to 3.

Embodiment 5. The difference between this embodiment and Embodiments 1 to 4 is that the sequencing batch Fenton oxidation reactor in step 3 runs for 3 cycles per day, and the others are the same as Embodiments 1 to 4.

Specific embodiment six, the difference between this embodiment and specific embodiments one to five is that the per cycle ferrous sulfate stock solution dosing flow rate of each group of reactors is 90L/min, and the per cycle hydrogen peroxide dosing flow rate of each group of reactors is 1.75L/min, the others are the same as those in Embodiments 1 to 5.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; meanwhile, for those of ordinary skill in the art, according to the present invention Thoughts, there will be changes in specific implementation methods and application ranges. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (7)

1. a sequential batch type Fenton oxidation reactor reagent dosing process control method, is characterized in that, described control method realizes by following steps: Step 1: Select the effluent from the refractory industrial wastewater biochemical treatment system as the industrial wastewater to be treated, the wastewater volume is 50-100m ³ /d, the COD concentration is 50-100mg/L, the ammonia nitrogen concentration is 10-30mg/L, Suspended solid SS concentration is 70-100mg/L; Step 2: Build an automatic control system for the Fenton reagent dosing process, the automatic control system for the Fenton reagent dosing process includes a ferrous sulfate storage solution deployment pool, a hydrogen peroxide storage pool, a sequencing batch Fenton oxidation reactor, Redox potential ORP online detector, computer with PLC controller installed, ferrous sulfate dosing metering pump, hydrogen peroxide dosing metering pump and metering pump controller; The bottom 20cm of the Oxidation Reactor, the middle depth, and 20cm below the water surface; the automatic control system of the Fenton reagent dosing process adopts the control parameter ORP setting value strategy: during the initial addition of Fenton reagent in the oxidation reaction process The ORP online detector in the batch-type Fenton oxidation reactor can measure the ORP value in the batch-type Fenton oxidation reactor in real time and continuously online. The computer data acquisition card collects and stores the value every 30s, and calculates the average value. The value is converted into a digital signal and input to the PLC controller; compared with the ORP set value of 450-500mV, the PID algorithm is used to calculate and output the digital signal calculation result, and the digital signal calculation result is converted into an analog signal and used as a metering pump control The metering pump controller controls the ferrous sulfate dosing metering pump and the hydrogen peroxide dosing metering pump to close, and stops adding the Fenton reagent; Step 3: Run the sequencing batch Fenton oxidation reactor, which includes 6 processes: water intake, pH adjustment, Fenton oxidation reaction, flocculation, sedimentation, drainage and sludge discharge, and the operating parameters are set as follows: hydraulic retention The time is 4-8h, the number of reactor groups is 1-3 groups, and each group of reactors operates 2-4 cycles per day; during each cycle of operation, the effluent of the biochemical pool stored in the regulating tank enters the sequence batch Fenton oxidation reaction In the reactor, the time of the water inlet process is 10-30min; after the water inlet process is completed, acid solution is added to the reactor, and the pH value in the reactor is adjusted to be 3-5, and the pH value adjustment process is entered, and the pH value adjustment process time is 5-10min, using mechanical stirring, the stirring speed gradient is 720-900s ^-1 ; The dosage of the Fenton reagent is regulated by the automatic control system of the Fenton reagent dosing process described in step 2. The mechanical stirring method is adopted. The stirring speed gradient is 720-900s ^-1 in the initial 10-30min of the process, and the stirring speed gradient is 240s in the remaining time. -300s ^-1 ; After the Fenton oxidation reaction process is finished, add lye to the reactor to adjust the pH value to 7-8, enter the flocculation process, the time is 20-40min, adopt mechanical stirring method, stir in the initial 5-10min The speed gradient is 720-900s ^-1 , and the stirring speed gradient is 20-60s ^-1 in the remaining time; after the flocculation process is completed, it enters the sedimentation process for 0.5h, and finally the drainage and sludge discharge process for 1-1.5h; Step 4: The Fenton reagent dosing process automatic control system described in step 2 is used to control the Fenton reagent dosing process of the sequencing batch type Fenton oxidation reactor, so that the sequencing batch type Fenton oxidation reactor reaches a stable working condition. 2. the sequence batch type Fenton oxidation reactor reagent adding process control method according to claim 1, is characterized in that, the ferrous sulfate stock solution concentration in step 2 is 22.67g/L, every group of reactors every cycle The dosing flow rate of the ferrous sulfate stock solution is 35-135L/min; the concentration of the hydrogen peroxide stock solution in step 2 is 330g/L, and the hydrogen peroxide dosing flow rate per cycle of each group of reactors is 0.2-2.5L/min. 3. the sequential batch type Fenton oxidation reactor reagent dosing process control method according to claim 1, is characterized in that, the ORP setting value of the PLC controller in the step 2 is 475mV. 4. The reagent dosing process control method of the sequencing batch type Fenton oxidation reactor according to claim 1, characterized in that, the hydraulic retention time of the sequencing batch type Fenton oxidation reactor in step 3 is 8h. 5. The reagent dosing process control method of the sequencing batch type Fenton oxidation reactor according to claim 1, characterized in that, the number of groups of the sequencing batch type Fenton oxidation reactor in step 3 is 2 groups. 6. The reagent dosing process control method of the sequencing batch type Fenton oxidation reactor according to claim 1, characterized in that, the sequencing batch type Fenton oxidation reactor in step 3 runs 3 cycles per day. 7. sequence batch type Fenton oxidation reactor reagent adding process control method according to claim 1, it is characterized in that, in step 2, every group of reactors every cycle ferrous sulfate stock solution adding flow rate is 90L/min, The hydrogen peroxide dosing flow rate per cycle for each group of reactors is 1.75L/min.