KR200281690Y1 - Apparatus for measuring COD - Google Patents

Abstract

Disclosed is a COD measuring apparatus using potassium dichromate method. Its configuration is a metering tube as a COD measuring device according to potassium dichromate method, which is equipped with various sample inlets and outlets, a reactor equipped with heating means, and various reagent supply units for supplying reagents for measuring COD with the reactor. (70), an air supply unit (50) for supplying air to the metering pipe (70), a tap water supply part (90) for supplying tap water to the metering pipe (70), and potassium dichromate to the metering pipe (70) The reagent metered in the metering tube 70 is provided with a metering tube 70 having a potassium bichromate supply unit 30 to supply and a ferrous ammonium sulfate supply unit 20 for supplying ferrous ammonium sulfate to the metering tube 70. The valve 71 is guided to the reaction tank 100 by opening and closing, and the reaction tank is characterized in that the electrode units 102 and 103 for detecting the redox potential in the reaction tank are provided as the COD detecting means.

Description

Siodi measuring apparatus by potassium dichromate method with metering tube {Apparatus for measuring COD}

The present invention relates to a COD measuring apparatus, and more particularly, it is provided with a metering tube to measure the reagent to be added to the reactor in advance to be supplied to the reactor

The present invention relates to an apparatus for measuring COD by the potassium dichromate method.

When selecting a source of water from a water supply, inspecting and monitoring the contamination or purification of the source, inspecting the acceptance of tap water for water quality standards, and determining whether the well is drinkable at a public health center, etc. B. Water analysis, which is carried out in the sewage system for each purpose, includes 29 types of water pollutants, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and dissolved oxygen as defined in the Enforcement Rules of the Framework Act on Environmental Policy. (DO), hydrogen ion concentration (pH), chromaticity, temperature, etc., which include bacteriological tests, biological tests, chemical tests, and physical measurements.

These are to test the same specimen from different angles using a unique method and finally make a decision by combining the results. It is desirable to investigate the environment of the site at the same time. It is common to make an appropriate judgment by doing this.

A bacteriological test is a test that gives the proper nutrients and temperature at which bacteria in water, especially Escherichia coli, can be cultivated and, as a result, measure the quantity or presence. The greatest advantage of this test is that it is the most sensitive detection of sewage and manure contamination and is therefore the best way to ensure hygienic safety.

E. coli is not an infectious disease, but because it is innumerably contained in manure, it can be assumed that manure is mixed directly or indirectly in the water where the bacterium is detected. Therefore, it is determined that this water may also contain infectious diseases of the gastrointestinal system (reared, typhoid, etc.), which is not suitable as a drink. Bacterial testing is also used to measure the efficiency of bacterial removal during water treatment. However, the bacteriology test has the drawback that it takes a long time (at least 24 hours) to get a result. Today, a method for short time measurement using isotopes or the like has been studied to eliminate this drawback, but it has not been put to practical use yet.

Biological tests are mainly used to measure the type and number of aquatic organisms using a microscope, and the results are to solve the obstacles caused by living organisms, and to check the operation efficiency, check and improve the treatment efficiency in the treatment method using living organisms. When used. Aquatic organisms can also determine the degree of fouling in the results of biological tests, taking advantage of the fact that the species and water differ according to the environmental water quality. In particular, since organisms reflect long-term water quality up to that time, past contaminations unknown by physicochemical and bacteriological tests can be estimated.

Finally, a physicochemical test is a test for measuring the type and amount of suspended solids and dissolved components in water, which has the advantage of being accurate in a relatively short time. The identification of poisons is an important test in the examination of poison contamination because there is no other method than this test. In addition, if the sewage and factory wastewater are contaminated, the unique components of each pollutant source will increase, so it is necessary to check the nature and quantity of the pollution. Knowledge gained by physicochemical tests is an important resource for determining the suitability of water purification operations and for adjusting the treatment methods.

The chemical oxygen demand is applied to natural waters such as rivers, lakes, and sea areas by adding aqueous solutions such as potassium permanganate (KMnO4) and potassium dichromate (K2Cr2O7) as oxidants to organic materials derived from municipal wastewater and factory wastewater. Oxygen equivalent to the amount of oxidant consumed for the oxidation of organic matter is expressed in mg / or ppm. The COD value depends on the type of oxidizing agent. In the test method of adding KMnO ₄ to an acidic or alkaline sample, the result value is easily changed depending on the conditions, and the entire amount of the organic material is difficult to oxidize. On the other hand, the test method based on K ₂ Cr ₂ O ₇ has negligible change in the result value according to the condition and has the advantage of oxidizing the whole amount of organic matter. Korea's pollution testing method has adopted the KMnO ₄ method since 1981, but is considering replacing it with the K ₂ Cr ₂ O ₇ method.

In the acidic KMnO4 method, 10 ml of 1: 2 H2SO4 was added to 300 ml of the sample and left for several minutes, 10 ml of 0.025 KMnO4 solution was added thereto, followed by water bath heating for 30 minutes, and then 10 ml of 0.02 Na2C2O4 was added again. Reverse titrate with 0.025 KMnO4 solution. The COD value is obtained by the following equation.

COD (ppm) = (b-a) × f × 1000 / V × 0.2

Where b: total 0.025 regulatory KMnO4 solution (mℓ) required for titration, a: 0.025 regulatory KMnO4 solution (mℓ) required for blank test, f: titer of regulatory KMnO4 (규정), V: volume of sample (mℓ) Means.

In alkaline KMnO4 method, 1mℓ of 20W / V% NaOH and 0.025 KMnO4 solution are added to 25 ~ 50ml of sample, and the water bath is heated for 60 minutes, and cooled by adding 1mℓ of 10W / V% KI solution, and then 10W / V H2SO4. 10 ml is added and titrated with 0.025 Na 2 S 2 O 3 solution. At this time, the COD value is obtained by the following equation.

COD (ppm) = (a-b) × f × 1000 / V × 0.2

Here, a: 0.025 prescribed Na2S2O3 solution (mℓ) used for a blank test, b: 0.025 prescribed Na2S2O3 solution (mℓ) used for titration, f: 0.025 titer of prescribed Na2S2O3, and V: amount of sample (ml).

In the K2Cr2O7 method, 25 ml of a 0.25 N K2Cr2O7 solution and 75 mL of concentrated sulfuric acid were added to 50 mL of the sample, heated for 2 hours, allowed to cool, and then titrated with dichromic acid remaining in a 0.25 N Fe (NH4) 2 (SO4) 2 solution. At this time, Ag2SO4 and HgSO4 are used as auxiliary reagents. The COD value is obtained by the following equation.

COD (ppm) = (a-b) N × 8000 / V

Where: a: Fe (NH4) 2 (SO4) 2 solution (mℓ) required for a blank test, b: Fe (NH4) 2 (SO4) 2 (mℓ) required for titration, N: Fe (NH4) 2 (SO4 2 means the prescribed degree of solution, and V: the amount of sample (ml).

On the other hand, the general type of COD measuring device currently supplied includes a method using potassium permanganate and a method using electrolysis and UV lamp (for example, Korean Patent Publication No. 1998-10422).

However, as described above, the method using potassium permanganate is easy to change the result value according to the conditions, it is pointed out that the entire amount of the organic material is difficult to oxidize, and the method using the electrolysis there is a risk that the error occurs due to the change in the power source. In the method using the UV lamp, there is a problem that the life of the UV lamp is short and the error of the measured value is greatly generated according to the change in the lamp intensity.

Therefore, the technical problem to be achieved by the present invention is a COD measuring device using potassium dichromate method, which does not have the problems of the existing COD measuring device as described above. It is to provide a COD measuring device by the potassium dichromate method.

1 is a main configuration diagram according to the device of the present invention.

The object of the present invention as described above is to provide a metering tube so that the reagent metered in the metering tube is guided to the reaction tank by opening and closing the valve, and special ceramics and platinum for judging the redox potential without corrosion, even at high concentrations of strong acids. It is attained by providing the COD measuring apparatus by the potassium dichromate method characterized by including the sensor.

The apparatus of the present invention is equipped with a COD by potassium dichromate method, which is equipped with various sample inlets and outlets, and has a reactor equipped with heating and stirring means and various reagent supply units for supplying reagents for measuring COD with the reactor. As a measuring device, the measuring device includes a metering tube, an air supply unit for supplying air to the metering tube, a tap water supply unit for supplying tap water to the metering tube, a potassium dichromate supply unit for supplying potassium dichromate to the metering tube, and the metering tube It is provided with a metering tube having a ferrous ammonium sulfate supply unit for supplying ferrous ammonium sulfate in the to ensure that the reagent metered in the metering tube is guided to the reaction tank by opening and closing the valve and the electrode portion for determining the potential of the induced sample It is characterized by being.

Hereinafter, a device of the present invention will be described in detail with reference to the accompanying drawings.

The device of the present invention is characterized in that various reagents to be introduced into a reaction tank in a conventional COD measuring device by potassium dichromate method are previously metered in a metering tube. Therefore, well-known devices and their descriptions are omitted, and a block diagram is shown in the drawings.

1 is a main configuration diagram according to the device of the present invention with reference to the drawings, the device of the present invention is a reactor 100 and various reagent supply units (10, 20, 30, 40, 50), sample supply unit ( 80, the metering pipe 70, the tap water supply unit 90, and the electrode portions 102 and 103 for measuring the redox potential of the organic material.

Although not shown, the reactor 100 is provided with a heater for heating, a stirrer for stirring the sample, various sample inlets and outlets.

The reactor is preferably made of Teflon and Pyrex materials, which are highly resistant to high temperature heating and chemical reactions.

The metering pipe 70 has an air supply unit 50 for supplying air, a tap water supply unit 90 for supplying tap water, a potassium bichromate supply unit 30 for supplying potassium dichromate, and a ferrous ammonium sulfate supply unit for supplying ferrous ammonium sulfate 20 is connected and each reagent is supplied to the metering tube 70 by the respective pumps 91, 31, 21.

In addition, the tap water pipe 70 is connected to the tap water supply unit 90 and the air supply unit 50 is connected to the reagent supply to the reaction tank (100).

In the device of the present invention, such a metering tube has the effect of reducing the consumption of reagents and improving accuracy by allowing the metering of reagents and samples to be metered in the first stage in the metering tube in the second stage.

The electrode portions 102 and 103 for measuring the redox potential in the reactor include a ceramic for comparing the ORP state with an oxygen redox potential (ORP) electrode 102, which is a redox potential electrode in which a platinum plate is deposited on a glass tube. The reference electrode 103 is made of brass wire.

In the drawing, reference numeral 101 denotes a cooling device for cooling the organic compound that is heated and vaporized in the reaction tank to reflux into the reaction tank 100. Reference numeral 93 is a valve for supplying tap water to the cooling device 101. Reference numeral 81 is a pump for pumping the sample into the tank, and 82 is a sample drain valve.

Hereinafter, an operation process according to the above device configuration will be described with reference to FIG. 1.

COD measurement according to the device of the present invention is divided into a preliminary measurement for determining the sample collection amount and this measurement for measuring the concentration of the sample on the basis of the value measured by the preliminary measurement. Therefore, the following description will be divided into preliminary measurement and main measurement.

1. Preliminary Measurement

1) The tap water tank 90 is used as dilution water, washing water and cooling water, and the tap water is opened and closed by the metering pipe valve 91 and the cooling valve 93, that is, the reaction tank 100 and the metering pipe 70. The water is sent to the cooling device 101.

The water content of the tap water tank 90 is 250 mL, and more is overflowed and drained. The tap water of the tap water tank 90 is introduced into the metering tube by the solenoid valve 91 and serves to clean the reaction tank 100 of the meter to remove contaminants.

2) The metering tube 70 measures the number of samples, dilution water, and reagents. The contents are 10 mL, and each liquid is detected and weighed by an electrode (LEVERLER). After the cleaning of the reaction tank 100 is finished, 20 mL of the sample is automatically introduced from the sample tank 80 into the metering tube by the calculation program of the controller of the measuring instrument, and the liquid metered by the metering tube solenoid valve 71 is introduced into the tank. It is.

3) The reactor is made of PYREX GLASS and has an oil bath (not shown) and a heater (not shown) for heating and reacting the sample. The drainage is cooled by blowing air. Stirring of the solution in the half tank has a stirrer (STIRRER) (not shown) at the bottom, whereby the solution in the reaction tank is stirred and reacted.

The temperature of the measured state uses silicone oil as the heat medium in the oil bath, and the heater is divided into two semi-circles with 400W (AC 100V), and a temperature sensor (not shown) for heating is attached in the middle.

After the sample is weighed, each volume of potassium dichromate and sulfuric acid-sulfuric acid is introduced into the reactor through the metering tube by the pumps 11 and 301 from the respective supply units 10 and 30 to cause a heating reaction at a high temperature in the reactor for 10 minutes. In the heating reaction, the oxidation and reduction potentials of the reaction tank were measured using the ORP indicator electrode 102 on which the platinum plate was deposited on the glass tube, and the potential was measured using the reference electrode ORP comparison electrode 103 made of ceramic and brass wire. Send to the operation unit of the control unit.

4) Add 80 mL of tap water from the tap water tank 90 to the heated sample and introduce the solution into the reactor by low speed rotation of the ferrous ammonium sulfate solution (FAS) pump (21). The rotary pump attaches a photoelectric detector (not shown) to the rotary shaft portion and divides one revolution into 32 equal parts to check and detect the input amount of the appropriate reagent.

5) After the titration is completed by the above process, the main measurement is started after the reaction vessel is cleaned.

2. This measurement

This measurement is performed based on the environmental process test method (chemical oxygen demand due to potassium dichromate) as a measurement for determining the concentration of the sample.

1) The tap water of the tap water tank 90 is introduced into the metering tube by the operation of the solenoid valve 91 and serves to remove the contaminants by cleaning the reaction tank 100 of the measuring instrument.

2) After the cleaning of the reactor is completed, 20 mL of the sample is automatically introduced into the metering tube by the sample solenoid valve by the program of the measuring instrument, and the liquid metered by the metering tube solenoid valve is introduced into the reactor.

3) The following procedure is the same as the preliminary measurement. At the end of the titration, the measured concentration value is recorded in the controller's memory, the foreign matter remaining in the reactor is cleaned and the operation is terminated.

According to the device of the present invention described above, it is equipped with a preliminary measurement function, and is adaptable to various wastewaters, and has a metering tube so that the metering of reagents and samples is carried out in the first metering pump and the second metering in the metering tube. It has the effect of reducing consumption and improving accuracy.

In addition, the problem of using potassium permanganate by the potassium dichromate method is overcome, and the use of electrodes as a COD detection means avoids the risk of fluctuations in measured values due to power fluctuations. The electrode does not need to be replaced for a relatively long time and the error of the measured value is reduced.

Claims (1)

Potassium dichromate having a reactor equipped with various sample inlets and outlets and a heating means, a reagent supply unit for supplying reagents for measuring COD with the reactor, and COD detection means for detecting COD of the target substance. In the COD measuring apparatus according to the method, The measuring device is a metering tube 70, the air supply unit 50 for supplying air to the metering tube 70, the tap water supply unit 90 for supplying tap water to the metering tube 70, the metering tube ( The metering tube (70) is provided with a potassium bichromate supply unit (30) for supplying potassium dichromate to the metering tube (70) having a ferrous ammonium sulfate supply unit (20) for supplying ferrous ammonium sulfate to the metering tube (70). Reagent metered in 70) is guided to the reaction tank 100 by opening and closing the valve 71, the reaction tank is provided with electrode portions (102, 103) for detecting the redox potential in the reaction tank as the COD detection means COD measuring apparatus by the potassium dichromate method, characterized in that.