JPS5956164A - Measuring method of amount of organic pollutant in water - Google Patents

Abstract

PURPOSE:To take a stable on-line measurement of the amount of organic pollutant in water from the production amount of CO2 by oxidation, by oxidizing test water with ozone. CONSTITUTION:While air is supplied to the test water in a reaction tank 1, acid is injected from a supply source 6 to <=4pH and the CO2 concentration in the water is balanced with that in the air. Then, alkali is injected from a supply source 7 to about 11pH and an ozonizer 2 is powered on to supply ozone to the test water, starting the integration of a computing element 9. Then, the ozone supply is stopped at a reaction end point and acid is injected into the test water again to <=4pH. Consequently, CO2 carried into the test water by the injected air and CO2 produced by the oxidation are discharged together with discharge gas, so that the CO2 concentration in the test water becomes equal to the concentration in the start of the reaction eventually. Thus, the output of the computing element 9 reduced to the negative side during the oxidation turns positive by an extent corresponding to the amount of CO2, and the concentration of the pollutant is known from said value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention oxidizes sample water with ozone and
2. Methods for Measuring the Amount of Organic Pollution in Water Based on the Amount of Production J. As water pollution in rivers, lakes, closed sea areas, etc. progresses, it is desired to expand the provision of measuring equipment for online measurement of water quality. Indicators of water pollution include BOD, which measures the amount of oxygen consumed by aerobic microorganisms when they oxidize pollutants in water; C to measure
There are ODMn, TOD, which burns test water in the presence of a decomposition medium, and measures the amount of oxygen consumed during the combustion. Furthermore, as a technology that has been attracting attention in recent years, the ultraviolet absorbance of sample water and CO
There is also a method (JV meter) that uses ultraviolet absorbance as an index of water pollution by taking advantage of the certain correlation between D and D. Of these, BOD usually takes 5 days to measure and is not suitable for online measurement. No. Automation has been attempted for COD, n, and TOD, but the former requires large amounts of reagents;
The latter method cannot be said to fully meet the requirements of an online measuring device, as replacing the catalyst and maintaining the water sampling system are complicated. On the other hand, the UV meter can be said to be suitable for on-line measurement as it has a completely different principle from the above method. However, as is well known, the absorbance of ultraviolet rays varies greatly depending on the substance, and in many cases cannot be used as an indicator of pollutants depending on the type of wastewater.

A method using ozone has been proposed as an alternative to these conventional water pollution analysis methods. This method oxidizes pollutants in water using ozone, which is a strong oxidizing agent, and determines the chemical oxygen demand (CODo3). This method does not require any reagents other than the alkali that accelerates the reaction, and since it is based on gas analysis, there are many problems such as contamination of the detection part that could not be avoided with conventional water quality analyzers. There are advantages.

However, since CODo includes oxygen consumption due to oxidation of inorganic compounds, it does not necessarily reflect the amount of organic pollution, which is a particular problem. In addition, in this method, the amount of oxygen consumed by ozone oxidation is minute compared to the oxygen content of the atmosphere, so high accuracy is required in determining the temperature. Therefore, means such as automatic calibration of the oxygen analyzer are also required, which complicates the apparatus.

The present invention was developed in view of the shortcomings of conventional water pollution measuring methods, and is characterized by measuring the amount of carbon dioxide produced by ozone oxidation. The objective is to provide a method for stable online measurement of Hereinafter, the present invention will be explained in detail based on examples.

The success or failure of the present invention is determined by focusing on how much of the organic carbon contained in pollutants in water is significantly promoted by ozone oxidation. TOC (Total Organic Carbo) when basic substances are treated with ozone for 2 hours
n) Removal rate was measured. It can be assumed that the removed TOC has become carbon dioxide, so this value indicates that organic carbon is Co
The rate of oxidation is up to 2. Table 1 shows the results. As shown by these results, it can be seen that on average of the 14 types of substances, about 80% of TOC was oxidized to CO2.

In this way, many right-hand brushes 1 CO2' in the alkaline region of surface carbon! CO generated when ozone oxidizes under these conditions.
By measuring 2, an index of water pollution level can be obtained. Of course, if other means for promoting the ozone oxidation reaction are effective, such as ultrasound, catalysts, ultraviolet rays, or hydrogen peroxide, then the appropriate method may be used, and if many of the pollutants are easily oxidized, There is no need for the above-mentioned means of promoting the Hiko reaction.

Next, an embodiment of the present invention is shown in FIG. In Figure 1, 1 is a reaction tank for collecting sample water and oxidizing it with ozone, 2 is an ozonizer, and 3 is a CO2 tank for measuring the difference in CO2 concentration between the exhaust gas from the reaction tank 1 and the injected air. densitometer, 4 a dehumidifier for removing moisture in the gas discharged from the reaction tank 1, 5 a dehumidifier for removing moisture from the injected gas, 6 an acid supply source, 7 an alkali supply source, 8 a dehumidifier for removing moisture from the gas discharged from the reaction tank 1; Flowmeter 9 is used to measure the injection gas flow rate; 9 is a calculator for integrating the product of the injection gas flow rate measured by flowmeter 8 and the C02a degree difference measured by concentration meter 3; 10 is a calculator for measuring the sample water reaction +! ! Sample water supply pump % 11 is a pump that supplies air to the ozonizer 2, and 12 is a pump that discharges sample water from the reaction tank 1.

The device operates as follows.

■Leveling the CO□ concentration in the test water While supplying air to the test water without generating ozone, inject acid so that p l-1 becomes 4 or less. In this state, most of the carbonic acid components in the water exist as CO2, so there is no need to consider the influence of carbonate ions. Therefore, if you continue to be exposed to water for a while, the CO4 degree in the water will come into equilibrium with the CO2 concentration in the atmosphere.

By this exposure, the CO2 concentration in the test water at the start of the reaction can be set constant.

(2) Oxidation reaction After injecting alkali to bring the pH to about 11, the ozone noizer is energized to supply ozone to the test water. At the same time, the calculator 9 starts integrating. Since the sample water is alkaline, almost all of the 〇〇, which was brought into the tank along with the CO2 produced by the first reaction and the ozonized air, becomes carbonate ions. Therefore, the exhaust gas does not contain CO2. On the other hand, the injected air contains CO2, so the difference in the C02 concentration between the exhaust gas and the injected air is negative, and this C02 concentration difference The integral value of the product of and the injected air flow rate, that is, the output of the calculator 9, continues to decrease in the negative direction.At the end of the reaction, this value is proportional to the amount of CO1 contained in the injected air and brought into the reaction tank. do.

■Release of CO, The reaction is terminated by stopping the power supply to the ozonizer.

At this point, the sample water contains carbonate ions produced by the oxidation reaction with the CO2 contained in the injected air, so in order to release this together with the exhaust gas, acid is injected into the sample water to adjust the pH. Set it to 4 or less. If you continue to ejaculate in this state, the carbon dioxide concentration in the sample water will eventually reach the equilibrium concentration with the atmosphere.

In other words, it becomes the concentration at the start of the reaction. The output of the calculator 9, which decreased to the negative side during the oxidation reaction, increases with the start of the release of CO□, and changes to a positive value by an amount corresponding to the amount of CO2 generated by the oxidation. Therefore, this value represents the pollutant concentration.

The present invention has been explained above based on examples, but this method using CO2 has the following advantages: (a) Since the CO22 degree in the air is low, the CO2 caused by the oxidation reaction
It is more suitable than the chemical oxygen demand value at 0, which is easy to detect the change amount of 9 degrees, and the organic pollutant concentration at 1.

It is excellent in that respect. Therefore, since the automatic water quality analyzer employing the method according to the present invention is based on gas analysis, it has fewer troubles and is easy to maintain, so it fully satisfies the requirements for an on-2-in measuring device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

Claims (1)

[Claims] 1) Ozone is supplied to a test water introduced into a reaction vessel, and organic pollutants in the test water are oxidized by the ozone, thereby measuring the amount of CO2 generated in a certain amount of the test water. A method for measuring the amount of organic pollution characterized by the following. 2. The method according to claim 1, which includes a pre-aeration step of aerating the test water with air in advance, an oxidation step of aerating the test water with ozonized air, and aeration of the test water again with air. and a post-aeration step, and the method is characterized in that the difference between the amount of CO2 flowing into the reaction vessel during the oxidation step and the amount of CO2 flowing out from the reaction container during the post-aeration step is measured. A method for measuring the amount of organic pollution in water. 3) In the method according to claim 2, the sample water is made acidic in the pre-aeration step and the post-aeration step, and the sample water is made alkaline in the oxidation step. Quantity measurement method.