WO2021022857A1 - Cod在线检测方法及使用该检测方法的设备 - Google Patents

Cod在线检测方法及使用该检测方法的设备 Download PDF

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WO2021022857A1
WO2021022857A1 PCT/CN2020/089490 CN2020089490W WO2021022857A1 WO 2021022857 A1 WO2021022857 A1 WO 2021022857A1 CN 2020089490 W CN2020089490 W CN 2020089490W WO 2021022857 A1 WO2021022857 A1 WO 2021022857A1
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cod
value
oxidant
orp
time
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PCT/CN2020/089490
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English (en)
French (fr)
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钟建华
张文英
潘裕富
钟卓鹏
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广东上智环保科技有限公司
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Priority claimed from CN201910718491.6A external-priority patent/CN110441376A/zh
Priority claimed from CN202010228498.2A external-priority patent/CN111257395A/zh
Application filed by 广东上智环保科技有限公司 filed Critical 广东上智环保科技有限公司
Publication of WO2021022857A1 publication Critical patent/WO2021022857A1/zh

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416Systems
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/18Water

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  • the invention relates to water quality COD detection technology, in particular to a COD online detection method and equipment using the detection method.
  • COD Chemical Oxygen Demand, Chemical Oxygen Demand
  • COD Chemical Oxygen Demand
  • the eutrophication pollution of lakes, reservoirs and other water bodies is closely related to the COD content in the water body. Excessive content will cause the abnormal reproduction and growth of various aquatic plants. Therefore, the detection of the COD content in the water body has important practical significance.
  • the current detection methods for COD content in water mainly adopt the national standard potassium dichromate oxidation method and permanganate index method.
  • the national standard "Determination of Chemical Oxygen Demand of Water Quality Dichromate Method” (HJ 828-2017) adopts heavy Potassium chromate method, its measurement principle is: add a known amount of potassium dichromate solution to the water sample to be tested, and use silver salt as a catalyst in a strong acid medium. After boiling and refluxing, use ferrous iron as an indicator Use ferrous ammonium sulfate to titrate the unreduced potassium dichromate in the water sample, and calculate the mass concentration of oxygen consumed from the amount of potassium dichromate consumed.
  • the national standard "The Potassium Permanganate Method for the Determination of Chemical Oxygen Demand (COD) in Industrial Circulating Cooling Water” (GB/T15456-2008) adopts the acid potassium permanganate method.
  • the principle of determination is: take a sample of water to be tested and add sulfuric acid Solution, saturated silver sulfate solution and potassium permanganate standard titration solution until heated to boiling, then boil for 5 minutes, cool to 60°C-80°C, add quantitative sodium oxalate standard solution until colorless, use potassium permanganate standard titration solution Drip back excess sodium oxalate.
  • These two national standard methods are complicated in process, time-consuming, difficult to measure in batches, and have disadvantages such as serious secondary pollution.
  • the electrochemical method of measuring COD has received widespread attention as a new type of rapid measurement method.
  • the principle is that according to the redox reaction caused by the electrode contact with the water sample, the current change is related to the concentration of organic matter, and the indirect measurement is COD value.
  • the electrochemical method of measuring COD generally includes two technical principles:
  • ozone generated by ozone (O 3 ) or electrolysis oxidizes organic matter in the water sample to be tested. Since the redox potential of ozone (O 3 ) is 2.07V, it can completely oxidize the macromolecular substances in the tested water sample.
  • the COD value of the water sample can be calculated.
  • the PHOENIX-1010 online COD automatic detector produced by the German STIP-SICO company, and the BD9372 online fast COD analyzer produced by Beijing Beidouxing are all based on this principle.
  • the advantage of this measurement method is that the measurement speed is fast and there is no secondary pollution. However, its instrument structure is still relatively complicated, with a large amount of operation and maintenance, high failure rate, and high cost.
  • Hydroxyl radicals ( ⁇ OH) produced by electrolysis oxidize the water sample to be tested, and the current consumed by the electrolytic oxidant can be corrected to calculate the COD value of the water sample according to Faraday's law.
  • the oxidation-reduction potential of hydroxyl radical ( ⁇ OH) is as high as 2.8V, which can completely oxidize the organic matter in the water sample to be tested and completely decompose into H 2 O and CO 2 .
  • the Elox-100A COD rapid monitor produced by the German LAR company uses a metal oxide lead dioxide electrode with strong catalytic performance to generate hydroxyl radicals with strong oxidizing ability to directly oxidize the organic matter in the tested solution.
  • the system has many advantages such as very simple equipment, high detection data accuracy, short detection and monitoring time, and low equipment failure rate.
  • the lead dioxide-based titanium electrode needs to regenerate the electrode every day or replace the electrode frequently to ensure the accuracy of the detection result, resulting in high maintenance costs and cumbersome use.
  • the COD direction of water quality detection still lacks a method and instrument that can achieve rapid detection, low price and easy maintenance.
  • the COD online detection method includes the following steps:
  • the ORP value of the mixed solution in the container is detected to the time point t x , and the ORP value of the mixed solution from t a to t x is obtained Among them, the value of t p is [t a , t x ], where t x >t b ;
  • the value of t p is [t b , t x ].
  • the ORP value determination step includes:
  • the COD value calculation step includes:
  • the step of determining a fitting function is further included:
  • the fitting function is established by the COD value of a series of COD standard solutions and the corresponding X t value.
  • ⁇ COD y ⁇ ' COD
  • y the correction coefficient
  • the correction coefficient y z( ⁇ , ⁇ , ⁇ );
  • is the temperature value of the mixed solution
  • is the inorganic salt content in the mixed solution
  • is the pH value of the mixed solution.
  • the range of the time point t x is (0, 30 min).
  • the oxidant includes at least one of ozone water, hydrogen peroxide water, and an aqueous solution containing hydroxyl radicals.
  • COD online detection equipment that uses the above-mentioned COD online detection method to measure COD.
  • ORP probe the ORP probe is arranged in the reactor
  • a sewage supply module which supplies sewage sample water to the reactor
  • the oxidant supply module provides oxidant to the reactor.
  • it further includes a pure water supply module, which is used to provide pure water to the reactor.
  • the oxidant supply module is connected to the reactor through a pure water supply module.
  • the oxidant supply module and the pure water supply module are respectively connected to the reactor.
  • it further includes:
  • a correction module which is arranged in the reactor
  • the calibration module includes at least one of a temperature detection probe, an inorganic salt detection probe, and a pH value detection probe.
  • ORP and electrolysis oxidant to measure COD of sewage that is, by oxidizing the organic matter in the water sample to be tested, and measuring the change of ORP value of the water sample to be tested, the COD value in the water sample to be tested can be quickly measured. There is no need to determine the consumption of reactants by titration like the traditional way, ORP reading is fast, and rapid reading and online detection can be realized at the same time.
  • a series of operations such as data acquisition, calculation and oxidant input in the COD detection process do not require human involvement, and the COD value of sewage can be better detected online.
  • the COD online detection equipment corresponding to the present invention has simple structure, simpler operation, low maintenance cost, does not require other chemical titrants and calibrators, reduces secondary pollution, and is more environmentally friendly.
  • FIG. 1 is a schematic flowchart of an online COD detection method according to an embodiment.
  • Fig. 2 is a schematic flowchart of a COD online detection method according to another embodiment.
  • Fig. 3 is a time axis diagram of a COD online detection method according to an embodiment.
  • Fig. 4 is a time axis diagram of a COD online detection method according to another embodiment.
  • Fig. 5 is a schematic structural diagram of an online COD detection device according to an embodiment.
  • the present invention provides an online COD detection method, which measures the change of ORP (Oxidation-Reduction Potential) value of the water sample to be tested by oxidizing the organic matter in the water sample to be tested, and can quickly measure the COD in the water sample to be tested value.
  • ORP Oxidation-Reduction Potential
  • the redox potential is used to reflect the macroscopic redox performance of all substances in the aqueous solution. The higher the redox potential, the stronger the oxidation, and the lower the redox potential, the stronger the reduction. A positive potential indicates that the solution shows a certain degree of oxidation, and a negative potential indicates that the solution shows a certain degree of reduction.
  • a COD online detection method includes the following steps:
  • the oxidant is used to oxidize the organic matter in the sewage sample water.
  • the oxidant includes at least one of ozone water, hydrogen peroxide and an aqueous solution containing hydroxyl radicals.
  • the oxidant is ozone water.
  • the oxidant is hydrogen peroxide, for example, the oxidant is an aqueous solution containing hydroxyl radicals, for example, the oxidant is a mixed solution of ozone water and hydrogen peroxide, for example, the oxidant is a mixture of ozone water and an aqueous solution containing hydroxyl radicals, for example, the oxidant It is a mixed solution of hydrogen peroxide and an aqueous solution containing hydroxyl radicals.
  • the oxidant is a mixed solution of ozone water, hydrogen peroxide and hydroxyl radicals.
  • the oxidant also contains other oxidizing groups/oxides. In this embodiment , Do not cumbersome description.
  • the oxidant may be an oxidant produced by itself.
  • the oxidant is ozone water, which can be oxidized by preparing ozone water by an ozone generator before the test.
  • the oxidant may also be an oxidant product obtained in other ways, such as , Industrial production of commercially available hydrogen peroxide solution or other oxidants.
  • Table 1 shows the oxidation-reduction potentials of various oxides. The higher the oxidation-reduction potential, the better the oxidation performance.
  • the time for adding the oxidizer and the sewage sample water to be tested can be the same time, that is, the oxidizer and the sewage sample water to be tested are added at the same time, or the oxidant can be added first, and then the sewage sample water to be tested and the sewage sample water are added.
  • the oxidizer is mixed.
  • the time of adding the oxidant is taken as t a
  • this time definition (ie, "the time to add the oxidant is t a ", and the time to add the sewage sample water is t b "), in each embodiment, does not include the above step (a ) Or the following steps (b) or other steps are summarized, and the claims/instructions before and after step (a) or (b) or between other steps are only for the convenience of explaining the upper and lower steps, and should not It is considered that “take the time of adding oxidant as t a and the time of adding sewage sample water as t b ”is a step in the ORP value determination step or a certain step in the ORP value determination step (for example, step (a), Part of step (b)).
  • the oxidant and the sewage sample water to be tested are mixed and reacted for a period of time, up to the time point t x described in this step.
  • the final measurement point should be the time point when the organic matter in the sewage sample water is completely oxidized by the oxidant, that is, the reaction end point. Therefore, the time point t x is the reaction The end point or the time point near the end of the reaction.
  • the time point t x is determined indirectly based on the change in the ORP value, and is not determined explicitly based on the way the reactants are exhausted as in the traditional titration method.
  • the value of t p is [t a , t x ], Is the ORP value corresponding to t p .
  • t p can be t a
  • t p can be t x
  • t p can be any time point in the range of [t a , t x ]
  • the number of t p can be one
  • the number of t p can be There are multiple, and the situation is explained in detail through the following:
  • the ORP value detection in the process from t a to t x is a time continuous detection, and what is obtained is a continuous ORP value reading, that is to say, Regarding the continuous change line of t p , specifically, it is a continuous ORP value change line within the time range of [t a , t x ].
  • t p is any point in [t a , t x ], Is the ORP value corresponding to any t p on the continuous change line.
  • the oxidant and the sewage sample water to be tested are not added at the same time.
  • the oxidant is added first, and then the sewage sample water to be tested is mixed with the oxidant (that is, t a ⁇ t b ), but the ORP value is measured after adding the sewage sample water to be tested.
  • the value of t p is [t b , t x ]
  • the value of t p in the range of [t b , t x ] can be the same as the above-mentioned t p in [t a , T x ]
  • the value method of the range that is, the above-mentioned 1-4). In order to avoid repeated descriptions, redundant descriptions are not made in this embodiment.
  • the ORP value determination step includes:
  • the number of t 0 can be one, the number of t 0 can be multiple, and the number of t 0 can correspond to versus Calculate the value of X COD to obtain the difference in redox potential before and after oxidation of the solution.
  • the number of t 0 is one, where t 0 corresponds to It should be the ORP value before the solution reaction or close to the beginning of the reaction process.
  • t 0 can be the time point t a when the oxidant is added
  • t 0 can be the time point t a when the oxidant is added and the sewage sample water
  • the time point between t b that is, t 0 can be a certain time point in [t a ,, t b ]
  • t 0 can be the time point t b when the sewage sample water is added
  • t 0 can be the sewage sample water added
  • t 0 can be the sewage sample water added
  • t 0 can be a time in (t b , t x ), and it should be understood that when the value of t 0 is within the range of (t b , t x ) and t When there is only one 0 , t 0 should be a time
  • the value of the first t 0 (t 0 1 ) is as described in t 0 above Specifically, t 0 1 can be the time point t a when the oxidant is added, and t 0 1 can be the time point between the time t a and the sewage sample water t b when the oxidant is added, that is, t 0 1 can be [t a , t b ] at a certain time point, t 0 1 can be the time point t b when the sewage sample water is added, t 0 1 can be a certain time point after the sewage sample water is added, that is, t 0 1 can be ( t b , t x ), and it should be understood that when the value of t 0 1 is in the range of (t b , t x ) and
  • the other t 0 (t 0 2 , t 0 3 ⁇ ) can be taken in the same way as t 0 1 , and t 0 1 ⁇ t 0 2 , t 0 3 ⁇ , that is (t 0 2 , t 0 3 ⁇ ) is the subsequent point of t 0 1 ; or, the value range of the remaining t 0 (t 0 2 , t 0 3 ⁇ ) can be [t a , t x ) and t 0 1 ⁇ t 0 2 , t 0 3 ⁇ , that is, the value range of other t 0 (t 0 2 , t 0 3 ⁇ ) is [t 0 , t x ), where t 0 ⁇ t a , and the rest
  • the value range of t 0 (t 0 2 , t 0 3 ⁇ ) is not limited to a time point close to the time point t b .
  • the range of the time point t X is (0, 30 min). It should be understood that the t X point should be the end of the reaction or a time point close to the end of the reaction.
  • the ORP value created by the present invention can be measured by a probe Realize fast reading, that is, follow up the oxidation-reduction reaction process in real time and read the ORP value at that point in time, so as to realize fast online measurement of ORP value.
  • (d) Provide can be based on Calculate the fitting function of the COD value by using the fitting function to obtain the COD value of the sewage sample water.
  • the COD value calculation step includes: (d 1 ) providing a fitting function that can calculate the COD value according to the X COD value, and using the fitting function The function gets the COD value of the sewage sample water.
  • the present invention provides a fitting function that can calculate the COD value according to the X COD value.
  • the fitting function determination step is further included:
  • the ORP value of the mixed solution in the container is detected to the time point t x'to obtain the ORP value of the mixed solution from t 1 to t x'
  • t is the value marked [t 1, t x], where, t x> t 2;
  • t is the standard value of t p the above-described embodiment the detection step is the same, i.e. as described above 1-4, i.e. Line may be a continuous change in the standard in t, P t for the [t 1, t x '] of any point, subscript t may be a plurality of time points, It is the ORP value corresponding to the t mark , and the description is not redundant in this embodiment.
  • the step of determining the fitting function includes:
  • the time t 1 for adding the oxidant in the step of determining the fitting function can be the same as the time t a of adding the oxidant in the step of determining the ORP value, or it can be slightly adjusted.
  • the time t 2 for adding the COD standard solution in the step of determining the fitting function It can be the same as adding sewage sample water t b in the ORP value determination step, or it can be slightly adjusted.
  • V sewage sample water is the sewage sample water volume
  • V oxidant is the oxidant volume
  • C oxidant is the oxidant concentration
  • ⁇ 'COD is the calculated COD value.
  • is The temperature value of the mixed solution
  • is the inorganic salt content in the mixed solution
  • is the pH value of the mixed solution.
  • the amount of oxidant used should in principle be greater than or far greater than the amount of oxidant that is theoretically required to completely oxidize the organic matter in the sewage sample water to be tested.
  • the quantitatively determined concentration of oxidant in the present invention is a process of establishing a specific fitting function, measuring the sewage sample water to be tested, and calculating the COD value according to the specific fitting function.
  • a fitting function is used, other concentrations and volumes of oxidants can be provided for function fitting. As long as the concentration and volume of the oxidant used to establish a certain fitting function are equal to the concentration and volume of the oxidant reacted by the sewage sample water to be measured into this certain fitting function for calculation.
  • the range of the reaction temperature is (0,50°C), that is, the temperature of the mixed solution is 0-50°C.
  • the oxidant is a solution containing ozone water, ozone is easily decomposed in water, and its decomposition rate Affected by temperature, the higher the temperature, the faster the decomposition rate of ozone in water, and due to the temperature requirements of other factors in the oxidation-reduction reaction, the reaction temperature of 0-50°C is adopted.
  • the OPR value measured by the COD standard solution with a certain concentration range is configured to calculate the fitting function of the COD concentration within the range with respect to the OPR value, and the ORP value of the sewage sample water to be measured can be substituted into the simulation
  • the combined function directly calculates the COD value, realizing online rapid measurement of COD. It is worth mentioning that the more samples of the COD standard solution, that is, the more concentration samples are set in the concentration range, the smaller the gradient change and the more accurate the established fitting function.
  • the COD standard solution of the discrete point is configured according to the discrete point of the non-standard solution value in the concentration range, and the OPR value is measured, and calculated according to the fitting function
  • the COD value of is compared with the standard value, and the root mean square error and relative error are calculated to obtain the accuracy of the fitting function.
  • the function may be different according to the different concentration range (that is, the difference of the COD concentration).
  • different fitting functions can be fitted to high and low concentrations, or a unified fitting function can be established for multiple concentration ranges. , Which determines the specific definition of the fitting function according to the actual situation to improve accuracy.
  • the time of adding oxidant is taken as 0 o'clock, and the time of adding sewage sample water is taken as t b , where t x > t b .
  • Measure the ORP value at 0 point to get By using Value and Calculate the value to get the redox potential change X COD value.
  • the ORP value potential change X COD value before and after the reaction between the oxidant and the sewage sample water to be measured can be obtained.
  • step (A) By using Value and Calculate the value to get the redox potential change X COD value.
  • the COD value of the sewage sample water to be tested is calculated.
  • the concentration and volume of the oxidant in step (A) and step (B) are equal, and the volume of the COD standard solution in step (A) and step (B) is equal to the volume of the sewage sample water.
  • Table 2 is a test data table of a preferred embodiment, as shown in the table:
  • the present invention provides a COD online detection device used in the above COD online detection method, including:
  • the reactor 300, the ORP probe 401, the sewage supply module 100 and the oxidant supply module 200 is set in the reactor 300 for detecting the ORP value of the solution.
  • the sewage supply module 100 is used for supplying sewage samples to the reactor 300
  • the oxidant supply module 200 is used to supply the oxidant to the reactor 300.
  • the reactor 300 is provided with a sewage inlet and an oxidant inlet
  • the sewage supply module 100 is connected to the sewage inlet of the reactor 300 through a pipe
  • the oxidant supply module 200 is connected to the oxidant inlet of the reactor 300 through a pipe.
  • the reactor 300 is connected to the sewage supply module 100 and the oxidizer supply module 200 through pipes, and each pipe is provided with a metering pump for quantitatively supplying the oxidizer and the sewage sample water to be tested to the reactor 300 .
  • the sewage supply module includes a sewage sample water tank 101, a filter 103, and a sewage supply pipe 102.
  • the sewage supply pipe 102 is used to supply sewage raw liquid, and the sewage supply pipe 102 is connected to the sewage sample water tank 101 through the filter 103.
  • the sewage sample water tank 101 supplies filtered sewage sample water to be tested to the reactor 300.
  • the sewage sample water tank 101 is connected to the reactor 300 through a pipe, and a metering pump is provided on the pipe.
  • the filter 103 can pre-process and filter out pollutants such as large particles and other undetectable components in the sewage raw liquid.
  • the filter 103 is a filter to avoid affecting the measurement results, improve the measurement accuracy, and improve the instrument (ORP The service life of the probe).
  • the COD online detection equipment further includes a pure water supply module 500, which is connected to the reactor 300 through a pipeline, and the pure water supply module 500 is used to supply pure water to the reactor and can be used to clean the reactor 300
  • the internal and ORP probe 401 prevents the residual sewage solution from affecting the subsequent test results, thereby improving the accuracy of the measurement.
  • the oxidant supply module is connected to the reactor through a pure water supply module.
  • the pure water supply module includes a pure water tank, which is connected to the reactor through a pipe, and the oxidant supply module includes an oxidizing group generator,
  • the oxidizing group generator is connected to the pure water tank and the connected pipe is provided with a first pump head.
  • the pure water tank supplies pure water to the oxidizing group generator.
  • the first pump head can oxidize the oxidizing group generator.
  • the radical water (oxidant) is transported back into the pure water tank, and the pure water tank transports the oxidized radical water into the reactor through the pipeline.
  • the pure water tank and the oxidizing group generator are connected through a pipeline to form a circulation loop, and the pure water/oxidizing group water is circulated and transported through the first pump head.
  • the actual meaning is to circulate the electrolysis of the pure water until the oxidant A fixed concentration is reached.
  • the pure water tank and the reactor are connected by a pipeline to form a circulation loop, and the pipeline is provided with a circulation pump, and the oxidation group water/pure water circulation can be realized by the circulation pump.
  • the oxidant supply module and the pure water supply module are respectively connected to the reactor, the pure water supply module includes a pure water tank, the pure water tank is connected to the reactor through a pipeline, and the oxidant supply module includes an oxidation group generator, A second pump head is provided on the pipe connecting the oxidation group generator and the reactor, and the pure water tank supplies pure water to the reactor.
  • the water in the reactor is transported to the oxidation group generator to produce oxidation group water. It is transported back into the reactor through the second pump head.
  • the reactor and the oxidation group generator are connected through a pipeline and form a circulation loop, and the pure water/oxidation group water is circulated and transported through the second pump head.
  • the actual meaning is to circulate the electrolysis of the pure water until the oxidant reaches Fixed concentration.
  • the reactor is provided with a waste water outlet, and the waste water outlet is connected with a waste water drainage pipe 600.
  • the COD online detection device further includes:
  • the calibration module is arranged in the reactor.
  • the calibration module includes at least one of a temperature detection probe 402, an inorganic salt detection probe 403, and a pH value detection probe (not shown).
  • the calibration module includes an inorganic salt detection probe
  • the calibration module includes a temperature detection probe.
  • the calibration module includes a pH detection probe.
  • the calibration module includes an inorganic salt detection probe and a pH detection probe.
  • the calibration module includes temperature detection. Probes and inorganic salt detection probes.
  • the calibration module includes a pH value detection probe and a temperature detection probe.
  • the calibration module includes a temperature detection probe, an inorganic salt detection probe and a pH value detection probe.
  • the temperature detection probe is used to detect the temperature value of the mixed solution in the reactor during the COD value detection process
  • the inorganic salt detection probe is used to detect the content value of inorganic salt
  • the pH value detection probe is used to detect the pH value, etc.
  • the data is used to The parameters ⁇ , ⁇ , and ⁇ in the fitting function are determined, and the correction coefficient is determined to further improve the accuracy of COD value detection.
  • the COD online detection device further includes a calculation module and a judgment module (not shown).
  • the calculation module is used to calculate the COD value based on the detection data of the ORP detection probe 401, the temperature detection probe 402, the inorganic salt content detection probe 403, the pH value detection probe, etc., in combination with the fitting function.
  • the judgment module is used to detect whether the reducing substance in the mixed solution has reacted completely according to a preset detection method.
  • the oxidant is directly supplied to the reactor to react with the sewage sample water to be tested, it avoids the electrode loss problem caused by the three-electrode method in the three-electrode method when the electrode is set in the reactor to generate oxidizing groups for oxidation.
  • the loss of the ORP probe is small. Long life and no need for regeneration.
  • the disclosed device and method may be implemented in other ways.
  • the device embodiments described above are only illustrative, for example, the division of units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components can be combined or integrated. To another system, or some features can be ignored, or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
  • each unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium.
  • the technical solution of this application essentially or the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including several instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in each embodiment of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes.
  • the COD online detection method detects the COD value of sewage, which can be continuously read online, and accurate detection results can be obtained in a short time (about 30 minutes).
  • the detection process of the COD online detection method provided by the embodiments of the present invention is simple and easy to operate, and the corresponding COD online detection equipment has simple structure, easy operation, low maintenance cost, and does not require other chemical titrants and calibrators, which not only improves detection efficiency, It also simplifies the measurement process and reduces the cost of the instrument.
  • the detection device used in the COD online detection method provided by the embodiment of the present invention has a small footprint, low cost, and safe operation process without risk.

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  • Treatment Of Water By Oxidation Or Reduction (AREA)

Abstract

一种COD在线检测方法及设备,其结合ORP与电解氧化剂对污水COD进行测定,即通过氧化待测水样中的有机物,测量待测水样的ORP值变化,能够快速测量待测水样中的COD值,无需像传统方式通过滴定确定反应物耗费量,ORP读数快,可同时实现快速读数和在线检测; COD检测过程中的数据获取、计算以及氧化剂的投入等一系列操作无需人为参与,自动化对污水COD值进行在线检测;对应的COD在线检测设备,结构简单,操作容易,维护成本低,无需其他化学滴定剂、校准剂,减少二次污染,更加环保。

Description

COD在线检测方法及使用该检测方法的设备 技术领域
本发明涉及水质COD检测技术,特别是涉及COD在线检测方法及使用该检测方法的设备。
背景技术
COD(Chemical Oxygen Demand,化学需氧量)是评估水体污染的重要综合指标之一,主要反映了水体受有机物污染的程度。湖泊、水库等水体的富营养化污染与水体中COD含量密切相关,其含量过高会引起各种水生植物的异常繁殖和生长,因此,对水体中的COD含量的检测具有重要的实际意义。
目前的水体COD含量检测方法主要采用国家标准重铬酸钾氧化法和高锰酸盐指数法,国家标准《水质化学需氧量的测定重铬酸盐法》(HJ 828-2017)中采用重铬酸钾法,其测定原理为:在待测水样中加入已知量的重铬酸钾溶液,并在强酸介质下以银盐作催化剂,经沸腾回流后,以试亚铁灵为指示剂,用硫酸亚铁铵滴定水样中未被还原的重铬酸钾,由消耗的重铬酸钾的量计算出消耗氧的质量浓度。国家标准《工业循环冷却水中化学需氧量(COD)的测定高锰酸钾法》(GB/T15456-2008)中采用酸性高锰酸钾法,其测定原理为:取待测水样加硫酸溶液、硫酸银饱和溶液及高锰酸钾标准滴定溶液至加热沸腾,再煮沸5min,冷却至60℃-80℃后,滴加定量草酸钠标准溶液至无色,用高锰酸钾标准滴定溶液回滴过量的草酸钠。这两种国标方法工序复杂、耗时长、批量测定难,且存在严重的二次污染等缺点。
近几年,电化学法测量COD作为一种新型的快速测定方法得到广泛关注,其原理为,根据电极与水样接触后引起氧化还原反应,其电流的变化与有机物的浓度相关,间接测量出COD值。
电化学法测量COD一般包括两种技术原理:
(1)臭氧氧化-电化学测量法。
其中,臭氧氧化-电化学测量法中,由臭氧(O 3)或电解产生的臭氧氧化待测 水样中的有机物。由于臭氧(O 3)的氧化还原电位为2.07V,可以将被检测水样中大分子物质完全氧化,通过测量氧化剂(O 3)的消耗量或电解产生臭氧消耗的电量,根据法拉第定律,经校正后可计算出水样的COD值。例如德国STIP—SICO公司生产的PHOENIX-1010在线COD自动检测仪、北京北斗星生产的BD9372在线快速COD分析仪都是基于该原理。这种测量方法的优点是测量速度快无二次污染。但其仪器结构仍然比较复杂,操作维护量大,故障率高,成本高。
(2)羟基及臭氧氧化-电化学测量法。
由电解产生的羟基自由基(·OH)氧化待测水样,由电解氧化剂消耗的电流,根据法拉第定律,经矫正后可计算出水样的COD值。羟基自由基(·OH)的氧化还原电位高达2.8V,可彻底氧化待测水样中的有机物并完全分解为H 2O和CO 2。例如,德国LAR公司产生的Elox-100A型COD快速监测仪,利用具有强催化性能的金属氧化物二氧化铅电极,电解产生具有强氧化能力的羟基自由基直接氧化被检测溶液中的有机物。该系统具有设备十分简单、检测数据准确度高、检测监测时间短,设备故障率低等诸多优点。但是,由于二氧化铅钛基电极需每天对电极进行再生或频繁更换电极才能保证检测结果的准确度,造成维护成本高,使用繁琐的问题。
总结上述内容,目前,水质检测COD方向依然缺少一种可以实现快速检测、价格低廉而维护容易的方法及仪器。
发明内容
基于此,有必要提供一种特别是涉及COD在线检测方法,及使用该检测方法检测COD的设备。
COD在线检测方法,包括以下步骤:
ORP值确定步骤:
向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应;
取加入氧化剂的时间为t a,取加入污水样水的时间为t b,并且,
对容器中的混合溶液进行ORP值检测至时间点t x,得到t a至t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000001
其中,t p的取值为[t a,t x],其中,t x>t b
COD值计算步骤:
提供可根据
Figure PCTCN2020089490-appb-000002
值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
在一个实施例中,所述ORP值确定步骤中,t p的取值为[t b,t x]。
在一个实施例中,所述ORP值确定步骤包括:
向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应;
对容器中的混合溶液进行ORP值检测至时间点t x,得到t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000003
并且,
取加入氧化剂的时间为t a,取加入污水样水的时间为t b,其中,t x>t b,并且,
在[t a,t x)的时间范围内,取时间点t 0,测量t 0时间点的ORP值,得
Figure PCTCN2020089490-appb-000004
Figure PCTCN2020089490-appb-000005
值与
Figure PCTCN2020089490-appb-000006
值进行计算,得X COD值;
所述COD值计算步骤包括:
提供可根据X COD值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
在一个实施例中,还包括拟合函数确定步骤:
配置COD值在一定浓度范围内的系列不同浓度的COD标准溶液;
取定量定浓度的氧化剂导入容器中,并将各COD标准溶液分别与定量定浓度的氧化剂混合反应;
取加入氧化剂的时间为t 1,取加入COD标准溶液的时间为t 2,并且;
对容器中的混合溶液的进行ORP值检测至时间点t x,得到系列t a至t x时刻的混合溶液的ORP值X t标,其中,t 的取值为[t a-t x],其中,t x>t b
通过系列COD标准溶液的COD值及与其对应的X t标值,建立拟合函数。
在一个实施例中,建立的拟合函数为:ε’ COD=f(t x,X 0,X tx,V 污水样水,V 氧化 ,C 氧化剂)式中,V 污水样水为污水样水体积,V 氧化剂为氧化剂体积,C 氧化剂为氧化剂浓度,ε’ COD为计算得到的COD值。
在一个实施例中,对计算得到的ε’ COD值进行校正,其中ε COD=yε’ COD,y为校正系数。
在一个实施例中,
所述校正系数y=z(α),或者
所述校正系数y=z(β),或者
所述校正系数y=z(γ),或者
所述校正系数y=z(α,β),或者
所述校正系数y=z(α,γ),或者
所述校正系数y=z(β,γ),或者
所述校正系数y=z(α,β,γ);
其中,α为混合溶液的温度值,β为混合溶液中无机盐含量,γ为混合溶液的pH值。
在一个实施例中,所述时间点t x的范围为(0,30min]。
在一个实施例中,所述氧化剂包括臭氧水、双氧水和含羟基自由基的水溶液中的至少一种。
采用上述所述的COD在线检测方法测量COD的COD在线检测设备。
COD在线检测设备,其特征在于,包括:
反应器;
ORP探头,该ORP探头设置于所述反应器内;
污水供给模块,向所述反应器供给污水样水;
氧化剂供给模块,向所述反应器提供氧化剂。
在一个实施例中,还包括纯水供给模块,所述纯水供给模块用于向所述反应器提供纯水。
在一个实施例中,氧化剂供给模块通过纯水供给模块与反应器连接。
在一个实施例中,氧化剂供给模块和纯水供给模块分别与反应器连接。
在一个实施例中,还包括:
校正模块,该校正模块设置于所述反应器内;
所述校正模块包括温度检测探头、无机盐检测探头和pH值检测探头中的至少一种。
本发明的有益效果是:
结合ORP与电解氧化剂对污水COD进行测定,即通过氧化待测水样中的有机物,测量待测水样的ORP值变化,能够快速测量待测水样中的COD值。无需像传统方式通过滴定确定反应物耗费量,ORP读数快,可同时实现快速读数和在线检测。
本发明中,COD检测过程中的数据获取、计算以及氧化剂的投入等一系列操作不需要人为参与,能够更好的对污水COD值进行在线检测。
本发明对应的COD在线检测设备,结构简单,操作更简单,维护成本低,无需其他化学滴定剂、校准剂,减少二次污染,更加环保。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案,下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本发明的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动性的前提下,还可以根据这些附图获得其它的附图。
图1为一实施例的COD在线检测方法的流程示意图。
图2为另一实施例的COD在线检测方法的流程示意图。
图3为一实施例的COD在线检测方法的时间轴线图。
图4为又一实施例的COD在线检测方法的时间轴线图。
图5为一实施例的COD在线检测设备的结构示意图。
具体实施方式
下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例仅仅是本发明一部分实施例,而不是全部的实施例。基于本发明中的实施例,本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其它实施例,都属于本发明保护的范围。
本发明提供一种COD在线检测方法,通过氧化待测水样中的有机物,测量待测水样的ORP(Oxidation-Reduction Potential,氧化还原电位)值变化, 能够快速测量待测水样中的COD值。其中,氧化还原电位是用来反映水溶液中所有物质表现出来的宏观氧化还原性,氧化还原电位越高,氧化性越强,氧化还原电位越低,还原性越强。电位为正表示溶液显示出一定的氧化性,为负则表示溶液显示出一定的还原性。通过测量溶液中待测污水样水在被氧化剂氧化前后的ORP电位变化,且ORP电位变化对应有变化过程或变化曲线,本发明提供ORP值与COD值相关的拟合函数,通过测量前后ORP值变化,可以快速测得COD值。如图1所示,一种COD在线检测方法,包括以下步骤:
ORP值确定步骤:
(a)向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应。
氧化剂用于氧化污水样水中的有机物,其中,在优选的实施例中,该氧化剂包括臭氧水、双氧水和含羟基自由基的水溶液中的至少一种,例如,该氧化剂为臭氧水,例如,该氧化剂为双氧水,例如,该氧化剂为含羟基自由基的水溶液,例如,该氧化剂为臭氧水和双氧水的混合溶液,例如,该氧化剂为臭氧水和含羟基自由基的水溶液的混合物,例如,该氧化剂为双氧水和含羟基自由基的水溶液的混合溶液,例如,该氧化剂为臭氧水、双氧水和含羟基自由基的混合溶液,例如,该氧化剂中还含有其他氧化基团/氧化物,本实施例中,不累赘描述。
其中,该氧化剂可以为自行制取的氧化剂,例如,该氧化剂为臭氧水,可以在测试前通过臭氧发生器制取臭氧水进行氧化,其中,该氧化剂也可以为其他方式获得的氧化剂成品,例如,工业生产市售的双氧水溶液或其他氧化剂。
表1中显示了多种氧化物的氧化还原电位,其中,氧化还原电位越高,氧化性能越好。
氧化物 氧化还原电位(V)
FLUORINE氟 2.87
HYDROXYL RADICAL羟基自由基 2.80
OXYGEN ATOM氧原子 2.42
OZONE臭氧 2.07
HYDROGEN PEROXIDE双氧水 1.78
POTASSIUM PERMANGANATE高锰酸钾 1.70
CHLORINE DIOXIDE氯酸盐 1.57
CHLORINE氯气 1.36
表1
其中,应当理解的是,加入氧化剂和待测的污水样水的时间可以为同一时间,即同时加入氧化剂和待测的污水样水,也可以先加入氧化剂,再加入待测的污水样水与氧化剂混合。
其中,为了体现工序流程,例如,取加入氧化剂的时间为t a,取加入污水样水的时间为t b,其中,应该理解的是,若氧化剂和待测污水样水同时加入,则t a=t b,若先加入氧化剂,再加入待测的污水样水,则t a<t b,其情况根据具体工艺流程操作确定。
值得一提的是,此时间定义(即“取加入氧化剂的时间为t a”“取加入污水样水的时间为t b”),在各实施例中,均并不纳入上述的步骤(a)或后续所述的步骤(b)中或其他步骤汇总,且在权利要求/说明书中放入步骤(a)或(b)前后或是其他步骤之间仅是为了便于解释上下步骤,不应认为“取加入氧化剂的时间为t a,取加入污水样水的时间为t b”是为ORP值确定步骤中的一个步骤或是ORP值确定步骤中的某一步骤(例如步骤(a)、步骤(b))中的一部分。
(b)对容器中的混合溶液进行ORP值检测至时间点t x,得到t a至t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000007
其中,t p的取值为[t a,t x],其中,t x>t b
也就是说,将氧化剂和待测的污水样水混合反应一段时间,至此步骤所述的时间点t x。应该理解的是,为测量污水样水被氧化前后的氧化还原电位差,最终测量点应当在污水样水中的有机物被氧化剂全部氧化的时间点,即,反应终点,因此,时间点t x为反应终点或为靠近反应终点的时间点。但应该理解的 是,时间点t x的确定是根据ORP值的变化以间接确定,并非如传统滴定法明确地根据反应物耗尽的方式确定。
其中,t p的取值为[t a,t x],
Figure PCTCN2020089490-appb-000008
为t p对应的ORP值。具体地说,t p可以为t a,t p可以为t x,t p可以为[t a,t x]范围中的任何一个时间点,t p的数量可以为一个,t p的数量可以为多个,其情况通过下述内容具体解释:
①从t a到t x过程中的ORP值检测为时间连续的检测,得到的是连续的ORP值读数,也就是说,得到
Figure PCTCN2020089490-appb-000009
关于t p的连续变化线,具体的,是在[t a,t x]时间范围内连续的ORP值变化线。在此情况中,t p为[t a,t x]中的任何一个点,
Figure PCTCN2020089490-appb-000010
为连续变化线上与任何一个t p对应的ORP值。
②只检测t a和t x两个时间点溶液中的ORP值,得到与时间点t a对应的ORP值
Figure PCTCN2020089490-appb-000011
及与时间点t x对应的ORP值
Figure PCTCN2020089490-appb-000012
在此情况中,t p为t a和t x两个点,
Figure PCTCN2020089490-appb-000013
Figure PCTCN2020089490-appb-000014
Figure PCTCN2020089490-appb-000015
③取[t a,t x]范围内的多个时间点进行检测,其中,多个时间点中包括t x,得到多个时间点对应的ORP值。在此情况中,t p为包括t x的多个时间点,
Figure PCTCN2020089490-appb-000016
为多个时间点对应的ORP值。
④取[t a,t x]范围内的多个时间点进行检测,其中,多个时间点中包括t a和t x,得到多个时间点对应的ORP值。在此情况中,t p为包括t a和t x的多个时间点,
Figure PCTCN2020089490-appb-000017
为多个时间点对应的ORP值。
应该理解的是,上述实施方式只是部分优选的实施例,本发明创造的实施例不局限于上述所述,不应理解为t p的取值只限制与上述所述的方法。
其中,若氧化剂和待测污水样水同时加入,即t a=t b时,上述所述的t p的取值为[t a,t x],在本实施例中,等同于t p的取值为[t b,t x]。
或者,氧化剂和待测污水样水并非同时加入,如先加氧化剂再加入待测污水样水与氧化剂混合(即t a<t b),但ORP值从加入待测污水样水后开始测量,则t p的取值为[t b,t x],并且,在本实施例中,t p在[t b,t x]范围的取值方式可 以如同上述所述的t p在[t a,t x]范围的取值方式(即上述的①-④)。为避免重复描述,本实施例不进行累赘说明。
为体现溶液的氧化还原电位的前后变化,在一个实施例中,具体地,如图2所示,该ORP值确定步骤包括:
(a 1)向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应;
(b 1)对容器中的混合溶液进行ORP值检测至时间点t x,得到t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000018
并且,
取加入氧化剂的时间为t a,取加入污水样水的时间为t b,其中,t x>t b,并且,
(c 1)在[t a,t x)的时间范围内,取时间点t 0,测量t 0时间点的ORP值,得
Figure PCTCN2020089490-appb-000019
Figure PCTCN2020089490-appb-000020
值与
Figure PCTCN2020089490-appb-000021
值进行计算,得X COD值。
其中,应该理解的是,t 0的数量可以为一个,t 0的数量可以为多个,可以根据多个t 0对应的
Figure PCTCN2020089490-appb-000022
Figure PCTCN2020089490-appb-000023
值进行计算得X COD,得到溶液氧化前后的氧化还原电位变化差。
在一个实施方式中,t 0的数量取一个,其中,t 0对应的
Figure PCTCN2020089490-appb-000024
应为溶液反应前或接近反应过程开始的ORP值,例如,如图3所示,t 0可以为加入氧化剂的时间点t a,t 0可以为加入氧化剂的时间点t a和加入污水样水t b之间的时间点,即t 0可以为[t a,,t b]中的某个时间点,t 0可以为加入污水样水的时间点t b,t 0可以为加入污水样水后的某个时间点,即t 0可以为(t b,t x)中的某个时间点,且应该理解的是,当t 0的取值在(t b,t x)范围内且t 0只有一个时,t 0应该为靠近时间点t b的时间点。
在上述实施方式中,应该理解的是,若氧化剂和污水样水同时加入,即t a=t b,如图4所示,无[t a,t b]的时间范围,t 0的取值方式除去[t a,t b]的情况,其余不变。
进一步地,若t 0的数量若为多个,如t 0 1、t 0 2、t 0 3···,第一个t 0(t 0 1)的取值如上述t 0所述的情况,具体地,t 0 1可以为加入氧化剂的时间点t a,t 0 1可以为加入氧化剂的时间点t a和加入污水样水t b之间的时间点,即t 0 1可以为[t a,t b]中的某个时间点,t 0 1可以为加入污水样水的时间点t b,t 0 1可以为加入污水样水后的某个时间点,即t 0 1可以为(t b,t x)中的某个时间点,且应该理解的是,当t 0 1的取值在(t b,t x)范围内时且为第一个t 0,t 0 1应该为靠近时间点t b的时间点。其中,其余t 0(t 0 2、t 0 3···)的取值方式可以如同t 0 1,且t 0 1<t 0 2、t 0 3···,即(t 0 2、t 0 3···)为t 0 1的后续点;或者,其余t 0(t 0 2、t 0 3···)的取值范围可以为[t a,t x)且t 0 1<t 0 2、t 0 3···,即其余t 0(t 0 2、t 0 3···)的取值范围为[t 0,t x),其中,t 0≥t a,并且,其余t 0(t 0 2、t 0 3···)的取值范围不局限于靠近时间点t b的时间点。
应当理解的是,时间轴中0点的确定是相对的,例如,可以以时间点t a为零点,即t a=0。在本发明创造中,时间轴0点并非需要确定的因素,t x和t a之间的ORP值变化与0点无关。
其中,进一步地,所述时间点t X的范围为(0,30min]。应该理解的是,t X点应为反应的终点或靠近反应终点的时间点。本发明创造的ORP值可以通过探头实现快速读数,即实时跟进氧化还原反应进程而读出该时间点的ORP值,实现快速在线测量ORP值。
上述的ORP值确定步骤后,为COD值计算步骤,如图1所示:
(d)提供可根据
Figure PCTCN2020089490-appb-000025
值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
进一步地,根据上述所述,在一个实施例中,如图2所示,所述COD值计算步骤包括:(d 1)提供可根据X COD值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
本发明创造提供可根据X COD值算得COD值的拟合函数,具体地,在一个实施例中,还包括拟合函数确定步骤:
配置COD值在一定浓度范围内的系列不同浓度的COD标准溶液;
取定量定浓度的氧化剂导入容器中,并将各COD标准溶液分别与定量定浓度的氧化剂混合反应;
取加入氧化剂的时间为t 1,取加入COD标准溶液的时间为t 2,并且;
对容器中的混合溶液进行ORP值检测至时间点t x’,得到系列t 1至t x’时刻的混合溶液的ORP值
Figure PCTCN2020089490-appb-000026
其中,t 的取值为[t 1,t x],其中,t x>t 2
通过系列COD标准溶液的COD值及与其对应的
Figure PCTCN2020089490-appb-000027
值,建立拟合函数。
应当理解的是,建立拟合函数的步骤中,t 的取值方式与上述检测的工序的t p相同,也就是如同上述的①-④,也即
Figure PCTCN2020089490-appb-000028
可以为关于t 的连续变化线,t p为[t 1,t x’]中的任何一个点,t 也可以多个时间点,
Figure PCTCN2020089490-appb-000029
为t 对应的ORP值,本实施例中,不累赘描述。
其中,更具体地,该拟合函数确定步骤包括:
配置COD值在一定浓度范围内的系列不同浓度的COD标准溶液;
取定量定浓度的氧化剂导入容器中,并将各COD标准溶液分别与定量定浓度的氧化剂混合反应,对容器中的混合溶液进行ORP值检测至时间点t x’,得到t x时刻混合溶液的ORP值X 2,并且;
取加入氧化剂的时间为t 1,取加入COD标准溶液的时间为t 2,并且;
在[t 1,t x’)的时间范围内,取时间点t 0,测量t 0时间点的ORP值,得检测得其ORP值X 1
用X 1值与X 2值进行计算,得到系列X COD标值,通过系列COD标准溶液的COD值及与其对应的X COD标值,建立拟合函数。
其中,拟合函数确定步骤中加入氧化剂的时间t 1可以与ORP值确定步骤中加入氧化剂的时间t a相同,也可以进行略微的调整,拟合函数确定步骤中加入COD标准溶液的时间t 2可以与ORP值确定步骤中加入污水样水t b相同,也可以进行略微的调整。
其中,进一步地,建立的拟合函数为:
Figure PCTCN2020089490-appb-000030
Figure PCTCN2020089490-appb-000031
式中,V 污水样水为污水样水体积,V 氧化剂为氧化剂体积,C 氧化剂为氧化剂浓度,ε’ COD为计算得到的COD值。
其中,值得一提的是,氧化还原电位受溶液温度、pH(hydrogen ion concentration,氢离子浓度指数)等因素的影响,例如,pH低时,氧化还原电位高,pH高时,氧化还原电位低,因此,为使得测量结果更加准确、减少误差,在一个实施例中,对计算得到的ε’ COD值进行校正,其中ε COD=yε’ COD,y为校正系数。具体地,所述校正系数y=z(α),或者所述校正系数y=z(β),或者所述校正系数y=z(γ),或者所述校正系数y=z(α,β),或者所述校正系数y=z(α,γ),或者所述校正系数y=z(β,γ),或者所述校正系数y=z(α,β,γ);其中,α为混合溶液的温度值,β为混合溶液中无机盐含量,γ为混合溶液的pH值。
周全考虑温度、无机盐(如氯化物)等对测量结果产生的影响,并利用修正系数进行修正,在有效剔除这些影响的前提下,使得得到的数据更加准确且有效,使得COD值的计算结果更加准确。
应当理解的是,氧化剂的使用量原则上应大于或远大于待测污水样水中有机物完全被氧化理论所需消耗的氧化剂的量。
需要说明的是,本发明所述的定量定浓度的氧化剂,是为在建立一个特定拟合函数、测量待测污水样水并根据该特定拟合函数计算COD值的一个过程, 如果在建立另一个拟合函数时,可提供其他浓度和其他体积的氧化剂进行函数拟合。只要建立某一拟合函数所用的氧化剂的浓度和体积等于代入此某一拟合函数进行计算的待测的污水样水所反应的氧化剂的浓度和体积即可。
其中,氧化剂浓度越高,则待测溶液中有机物被氧化的速率越快,ORP值随着时间的变化而变化则越明显,使得测量误差、计算误差更差,获得的COD值越准确。
其中,进一步地,所述反应温度的范围为(0,50℃],即混合溶液的温度为0~50℃。例如,氧化剂为含有臭氧水的溶液,臭氧在水中易分解,且其分解速度受温度影响,温度越高,臭氧在水中的分解速率越快,以及由于该氧化还原反应中其他因素对温度的要求,因此,采用0~50℃的反应温度。
本发明创造中,通过配置一定浓度范围的COD标准液测出的OPR值,推导算出该范围内的COD浓度关于OPR值的拟合函数,通过测量待测污水样水的ORP值可代入该拟合函数直接算得COD值,实现在线快速测量COD。值得一提的是,COD标准液的样本越多,即在该浓度范围内设置越多浓度样本,其梯度变化量越小,建立的拟合函数越精确。并且在优选的实施例中,在建立拟合函数后,根据该浓度范围内的非标准液取值的离散点,配置该离散点的COD标准液,测量其OPR值,根据拟合函数计算得到的COD值,与标准值做对比,计算其均方根误差和相对误差,可以得出该拟合函数的精确度。
其中,函数可能根据浓度范围的不同(即COD浓度的不同)而不同,例如,在高浓度和低浓度分别拟合出不同的拟合函数,也可能多个浓度范围均建立统一的拟合函数,其根据实际情况确定具体定义拟合函数,以提高准确度。
下面结合实施例对本发明做进一步的详细描述,但应该理解的是,不应将下列实施例视为对本发明的限制。
实施例1
向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应。对容器中的混合溶液进行ORP值检测至时间点t x,得到t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000032
取加入氧化剂的时间为0点,取加入污水样水的时间为t b,其中,t x>t b。并测量0点处的ORP值,得到
Figure PCTCN2020089490-appb-000033
通过用
Figure PCTCN2020089490-appb-000034
值与
Figure PCTCN2020089490-appb-000035
值进行计算,得氧化还原电位变化量X COD值。
提供通过X COD值算得COD值的拟合函数,利用该拟合函数计算得到污水样水的COD值。
实施例2
向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应。
取加入氧化剂的时间为0点,取加入污水样水的时间为t b,从0点开始,对容器中的混合溶液进行连续的ORP值检测至时间点t x,其中,t x>t b,得到一条连续的ORP值读数曲线(即ORP值关于时间的连续变化线,该连续变化线包括若干个时间点t p及其对应的ORP值
Figure PCTCN2020089490-appb-000036
)。
根据该ORP值读数曲线,可以得到从氧化剂与待测的污水样水反应前后的ORP值电位变化量X COD值。
提供通过X COD值算得COD值的拟合函数,利用该拟合函数计算得到污水样水的COD值。
实施例3
(A):
配置COD值在一定浓度范围内的系列不同浓度的COD标准溶液。取定量定浓度的氧化剂导入容器中,并将各COD标准溶液分别与定量定浓度的氧化剂混合反应,对容器中的混合溶液进行ORP值检测至时间点t x,得到t x时刻混合溶液的ORP值X 2
取加入氧化剂的时间为0点,取加入COD标准溶液的时间为t b
在[t a,t x)的时间范围内,取时间点t 0,测量t 0时间点的ORP值,得检测得其ORP值X 1
用X 1值与X 2值进行计算,得到系列X COD标值,通过系列COD标准溶液的COD值及与其对应的X COD标值,建立拟合函数。
(B):
向容器中加入定量定浓度的氧化剂,取定量的待测污水样水与氧化剂混合反应。
对容器中的混合溶液进行ORP值检测至步骤(A)中所述的时间点t x,得到t x时刻混合溶液的ORP值
Figure PCTCN2020089490-appb-000037
测量步骤(A)中所述氧化剂的加入时间0点处的ORP值,得到
Figure PCTCN2020089490-appb-000038
通过用
Figure PCTCN2020089490-appb-000039
值与
Figure PCTCN2020089490-appb-000040
值进行计算,得氧化还原电位变化量X COD值。通过步骤(A)中提供的拟合函数,计算得到待测污水样水的COD值。
其中,步骤(A)和步骤(B)中氧化剂的浓度和体积相等,步骤(A)和步骤(B)中的COD标准溶液和测污水样水的体积相等。
其余实施方式,不累赘进行一一描述。
表2为一较佳实施例的检测数据表,如表所示:
ORP值 EC值 COD真值 实际运算COD值 相对误差
484 424 1090 1086.19009 -0.3%
484 436 1090 1093.47174 0.3%
481 431 1090 1090.65219 0.1%
479 419 1090 1081.89974 -0.7%
459 491 1090 1075.70751 -1.3%
472 533 1090 1088.82626 -0.1%
464 478 1090 1085.96725 -0.4%
458 507 1090 1071.13607 -1.7%
468 587 1090 1083.75267 -0.6%
483 556 1090 1091.23396 0.1%
412 421 961.2 936.55099 -2.6%
422 412 961.2 954.8849 -0.7%
427 417 961.2 972.19407 1.1%
428 424 961.2 980.0218 2.0%
417 422 961.2 949.81955 -1.2%
430 423 961.2 984.6706 2.4%
428 427 961.2 982.02731 2.2%
423 425 961.2 967.4549 0.7%
398 358 854.4 831.44734 -2.7%
393 422 854.4 894.18611 4.7%
382 437 854.4 882.20649 3.3%
383 425 854.4 876.8992 2.6%
369 426 854.4 854.2156 0.0%
361 433 854.4 846.94036 -0.9%
395 191 513 492.0959 -4.1%
345 228 513 489.69803 -4.5%
329 245 513 508.92832 -0.8%
445 228 513 489.69803 -4.5%
429 245 513 508.92832 -0.8%
327 150 327 316.77893 -3.1%
337 143 327 314.1923 -3.9%
334 158 327 338.40535 3.5%
337 149 327 325.02641 -0.6%
304 44 99 100.29499 1.3%
313 43 99 105.16973 6.2%
表2
如图5所示,本发明提供一种用于上述COD在线检测方法的COD在线检测设备,包括:
反应器300、ORP探头401、污水供给模块100和氧化剂供给模块200,ORP探头401设置于反应器300内,用于检测溶液的ORP值,污水供给模块100用于向反应器300供给污水样品,氧化剂供给模块200用于向反应器300供给氧化剂。其中,例如,反应器300上设有污水入口和氧化剂入口,污水供给模块100通过管道与反应器300的污水入口相连通,氧化剂供给模块200通过管道与反应器300的氧化剂入口相连连。
其中,在一个实施例中,反应器300通过管道分别与污水供给模块100以及氧化剂供给模块200相连接,各管道上设置有计量泵,用于向反应器300定量供给氧化剂和待测污水样水。
其中,在一个实施例中,污水供给模块包括污水样水箱101、过滤器103和污水供给管102,污水供给管102用于供给污水原液,污水供给管102通过过滤器103与污水样水箱101连接,并且,污水样水箱101向反应器300供给经过过滤的待测的污水样水,例如,污水样水箱101通过管道与反应器300连接,且管道上设置有计量泵。过滤器103能够预处理过滤掉污水原液中的大颗粒杂质等污染物及其他无法检测的成分,例如,过滤器103为滤网,从而避免影响测量结果、提高测量精确度,并且提高仪器(ORP探头)的使用寿命。
例如,所述COD在线检测设备还包括纯水供给模块500,纯水供给模块500通过管道与反应器300连接,纯水供给模块500用于向反应器供给纯水,可以用于清洗反应器300内部和ORP探头401,避免残留的污水溶液影响后续的检测结果,从而提高了测量的精确度。
在一个实施例中,氧化剂供给模块通过纯水供给模块与反应器连接,例如,纯水供给模块包括纯水箱,纯水箱通过管道与反应器连接,氧化剂供给模块包括氧化基团发生器,氧化基团发生器与纯水箱连接且连接的管道上设置有第一泵头,纯水箱向氧化基团发生器供给纯水,该第一泵头可以将氧化基团发生器产生的氧化基团水(氧化剂)输送回纯水箱内,纯水箱通过管道将氧化基团水输送至反应器内。进一步地,纯水箱与氧化基团发生器通过管道连接且形成循环回路,通过第一泵头对纯水/氧化基团水进行循环输送,其实际意义是对纯水进行循环电解,直到氧化剂达到固定浓度。进一步地,纯水箱与反应器通过管道连接且形成循环回路,该管道上设置有循环泵,通过循环泵可以实现氧化基团水/纯水循环。
在另一个实施例中,氧化剂供给模块和纯水供给模块分别与反应器连接,纯水供给模块包括纯水箱,纯水箱通过管道与反应器连接,氧化剂供给模块包 括氧化基团发生器,氧化基团发生器与反应器连接且连接的管道上设置有第二泵头,纯水箱供给纯水给反应器,反应器内的水输送至氧化基团发生器产生氧化基团水,再通过第二泵头输送回反应器内。进一步地,反应器与氧化基团发生器通过管道连接且形成循环回路,通过第二泵头对纯水/氧化基团水进行循环输送,其实际意义是对纯水进行循环电解,直到氧化剂达到固定浓度。
其他结构类型,不进行累赘描述。
例如,反应器设有废水排水口,废水排水口连通有废水排水管600。
在一个实施例中,该COD在线检测设备还包括:
校正模块,该校正模块设置于所述反应器内。校正模块包括温度检测探头402、无机盐检测探头403和pH值检测探头(图未示)中的至少一种。例如,校正模块包括无机盐检测探头,校正模块包括温度检测探头,例如,校正模块包括pH值检测探头,例如,校正模块包括无机盐检测探头和和pH值检测探头,例如,校正模块包括温度检测探头和无机盐检测探头,例如,校正模块包括pH值检测探头和温度检测探头,例如,校正模块包括温度检测探头、无机盐检测探头和pH值检测探头。
其中,温度检测探头用于检测COD值检测过程中反应器中混合溶液的温度值,无机盐检测探头用于检测无机盐含量值,pH值检测探头用于检测pH值等,并以此数据来确定所述拟合函数中的参数α、β和γ等,而确定修正系数,进一步提高COD值检测的准确性。
进一步地,在一个实施例中,该COD在线检测设备还包括计算模块和判断模块(图未示)。具体地,所述计算模块用于根据ORP检测探头401、温度检测探头402、无机盐含量检测探头403以及pH值检测探头等的检测数据,结合拟合函数来实现COD值的计算。具体地,判断模块用于根据预置检测方法检测混合溶液中的还原性物质是否已经反应彻底。
其中,由于使用将氧化剂直接供给反应器与待测污水样水反应,避免三电极法中反应器内设置电极进行反应产生氧化基团以氧化导致的电极损耗问题,本发明中ORP探头损耗小,寿命长,且无需再生。
在本申请所提供的几个实施例中,应该理解到,所揭露的设备和方法,可以通过其它的方式实现。例如,以上所描述的设备实施例仅仅是示意性的,例如,单元的划分,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式,例如多个单元或组件可以结合或者可以集成到另一个系统,或一些特征可以忽略,或不执行。另一点,所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口,装置或单元的间接耦合或通信连接,可以是电性,机械或其它的形式。
作为分离部件说明的单元可以是或者也可以不是物理上分开的,作为单元显示的部件可以是或者也可以不是物理单元,即可以位于一个地方,或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外,在本申请各个实施例中的各功能单元可以集成在一个处理单元中,也可以是各个单元单独物理存在,也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现,也可以采用软件功能单元的形式实现。
集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时,可以存储在一个计算机可读取存储介质中。基于这样的理解,本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来,该计算机软件产品存储在一个存储介质中,包括若干指令用以使得一台计算机设备(可以是个人计算机,服务器,或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括:U盘、移动硬盘、只读存储器(Read-OnlyMemory,ROM)、随机存取 存储器(RandomAccess Memory,RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
本发明实施例中提供的COD在线检测方法及设备,具有以下有益效果:
(1)由于氧化剂/氧化基团水所具备的强氧化性,适合不同污水水质的COD值检测,且无任何化学残留。检测后的水样中相当于经过了污水处理,无需进行后续处理,甚至可直接排放,避免了采用重铬酸钾氧化法和高猛酸盐指数法等检测COD含量的方法中存在的二次污染严重的问题。
(2)在污水水量样少的情况下,利用足量的一定浓度的氧化剂对其COD值进行检测,可有效缩短检测时间,提高检测值的精确度。
(3)本发明实施例提供的COD在线检测方法对污水的COD值进行检测,可连续在线读数,可在短时间内(约30分钟)得到准确的检测结果。
(4)本发明实施例提供的COD在线检测方法检测过程简单易操作,对应的COD在线检测设备结构简单,操作容易,维护成本低,无需其他化学滴定剂、校准剂,不仅提高了检测效率,还使得测量工序简单化,降低仪器成本。
(5)本发明实施例提供的COD在线检测方法所使用的检测装置,占地空间小,成本低,且操作过程安全无风险。
以上所述实施例的各技术特征可以进行任意的组合,为使描述简洁,未对上述实施例中的各个技术特征所有可能的组合都进行描述,然而,只要这些技术特征的组合不存在矛盾,都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本发明的几种实施方式,其描述较为具体和详细,但并不能因此而理解为对发明专利范围的限制。应当指出的是,对于本领域的普通技术人员来说,在不脱离本发明构思的前提下,还可以做出若干变形和改进,这些都属于本发明的保护范围。因此,本发明专利的保护范围应以所附权利要求为准。

Claims (15)

  1. COD在线检测方法,其特征在于,包括以下步骤:
    ORP值确定步骤:
    向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应;
    取加入氧化剂的时间为t a,取加入污水样水的时间为t b,并且,
    对容器中的混合溶液进行ORP值检测至时间点t x,得到t a至t x时刻混合溶液的ORP值
    Figure PCTCN2020089490-appb-100001
    其中,t p的取值为[t a,t x],其中,t x>t b
    COD值计算步骤:
    提供可根据
    Figure PCTCN2020089490-appb-100002
    值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
  2. 根据权利要求1所述的COD在线检测方法,其特征在于,所述ORP值确定步骤中,t p的取值为[t b,t x]。
  3. 根据权利要求1所述的COD在线检测方法,其特征在于,
    所述ORP值确定步骤包括:
    向容器中加入定量定浓度的氧化剂,取定量的污水样水与氧化剂混合反应;
    对容器中的混合溶液进行ORP值检测至时间点t x,得到t x时刻混合溶液的ORP值
    Figure PCTCN2020089490-appb-100003
    并且,
    取加入氧化剂的时间为t a,取加入污水样水的时间为t b,其中,t x>t b,并且,
    在[t a,t x)的时间范围内,取时间点t 0,测量t 0时间点的ORP值,得
    Figure PCTCN2020089490-appb-100004
    Figure PCTCN2020089490-appb-100005
    值与
    Figure PCTCN2020089490-appb-100006
    值进行计算,得X COD值;
    所述COD值计算步骤包括:
    提供可根据X COD值算得COD值的拟合函数,利用该拟合函数得到污水样水的COD值。
  4. 根据权利要求1或3所述的COD在线检测方法,其特征在于,还包括拟合函数确定步骤:
    配置COD值在一定浓度范围内的系列不同浓度的COD标准溶液;
    取定量定浓度的氧化剂导入容器中,并将各COD标准溶液分别与定量定浓度的氧化剂混合反应;
    取加入氧化剂的时间为t 1,取加入COD标准溶液的时间为t 2,并且;
    对容器中的混合溶液的进行ORP值检测至时间点t x’,得到系列t 1至t x’时刻的混合溶液的ORP值X t标,其中,t 的取值为[t 1,t x],其中,t x>t b
    通过系列COD标准溶液的COD值及与其对应的X t标值,建立拟合函数。
  5. 根据权利要求4所述的COD在线检测方法,其特征在于,建立的拟合函数为:
    Figure PCTCN2020089490-appb-100007
    式中,V 污水样水为污水样水体积,V 化剂为氧化剂体积,C 氧化剂为氧化剂浓度,ε’ COD为计算得到的COD值。
  6. 根据权利要求5所述的COD在线检测方法,其特征在于,对计算得到的ε’ COD值进行校正,其中ε COD=yε’ COD,y为校正系数。
  7. 根据权利要求6所述的COD在线检测方法,其特征在于,
    所述校正系数y=z(α),或者
    所述校正系数y=z(β),或者
    所述校正系数y=z(γ),或者
    所述校正系数y=z(α,β),或者
    所述校正系数y=z(α,γ),或者
    所述校正系数y=z(β,γ),或者
    所述校正系数y=z(α,β,γ);
    其中,α为混合溶液的温度值,β为混合溶液中无机盐含量,γ为混合溶液的pH值。
  8. 根据权利要求1所述的COD在线检测方法,其特征在于,所述时间点t x的范围为(0,30min]。
  9. 根据权利要求1所述的COD在线检测方法,其特征在于,所述氧化剂包括臭氧水、双氧水和含羟基自由基的水溶液中的至少一种。
  10. 采用权利要求1-9所述的COD在线检测方法测量COD的COD在线检测设备。
  11. COD在线检测设备,其特征在于,包括:
    反应器;
    ORP探头,该ORP探头设置于所述反应器内;
    污水供给模块,向所述反应器供给污水样水;
    氧化剂供给模块,向所述反应器提供氧化剂。
  12. 根据权利要求1所述的COD在线检测设备,其特征在于,还包括纯水供给模块,所述纯水供给模块用于向所述反应器提供纯水。
  13. 根据权利要求12所述的COD在线检测设备,其特征在于,氧化剂供给模块通过纯水供给模块与反应器连接。
  14. 根据权利要求12所述的COD在线检测设备,其特征在于,氧化剂供给模块和纯水供给模块分别与反应器连接。
  15. 根据权利要求1所述的COD在线检测设备,其特征在于,还包括:
    校正模块,该校正模块设置于所述反应器内;
    所述校正模块包括温度检测探头、无机盐检测探头和pH值检测探头中的至少一种。
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