CS256419B1 - Method for determination of nitrate, dissolved organic matter and water turbidity, especially surface, underground and drinking - Google Patents

Abstract

The method of determination consists in simultaneously passing ultraviolet radiation of two wavelengths and visible radiation through the water sample and measuring their absorbance. Using correction factors and conversion factors empirically determined for a given type of water, specific values of NO, COD and SiO2 (turbidity) are determined directly in ml/l.

Description

The invention relates to a method for the joint determination of nitrate, dissolved organic matter and turbidity of water, in particular surface, ground and drinking water.

The methods known hitherto consist in the separate determination of nitrates, dissolved organic substances and turbidity, by separate separate laboratory procedures, optionally using analyzers.

In particular, photometric procedures with sodium salicylate or a number of other photometric determinations are used for the determination of nitrates. The samples generally require treatment to remove suspended solids. Furthermore, a polarographic or potentiometric determination based on the use of ion-selective electrodes can be used.

The dissolved organic matter content is determined after filtering or centrifuging the sample according to the consumption of the oxidizing agent used to oxidize the organic matter. These procedures are time-consuming, especially in the dual chromium potassium method, which requires two hours of boiling oxidation in a strongly acidic environment. The determination of organic carbon, the amount of which is proportional to the organic matter content, can be carried out by means of special instruments.

Turbidity measurement is performed by turbidimetry as an arbitration method, by detecting radiation absorption at a certain wavelength in the visible region of the spectrum, or by nephelometriques by measuring the intensity of light reflected at a certain angle.

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These procedures place increased demands on time and on professional laboratory work. The results of the analyzes are known only with a certain time delay, which is disadvantageous in terms of operational management of water management systems and technology of treatment of these waters for industrial and drinking purposes.

It is an object of the present invention to overcome the above drawbacks. It is based on a method that allows the evaluation of water quality - whether continuously or discontinuously - from the point of view of the content of nitrates, dissolved organic substances and sludge, at the same time, reliably and quickly.

The principle of the method according to the invention is characterized in that ultraviolet radiation with a wavelength (L () lying in the range from 195 to 240 nm, ultraviolet radiation with a wavelength (Lg) lying in the range from 195 to 350 nm, passes through the water of interest. different from wavelength Lp and visible radiation of wavelength (Lg) lying in the range of 430 to 600 nm _z and the absorbance (A ^, A ₂ , Αθ) of these radiation being sensed and measured individually or simultaneously, the absorbance proportional to the nitrate concentration (AL ^) is determined by relation

ALj. - I - (Ag ** Ag · kg). kg · Ag · j absorbance proportional to the concentration of dissolved organic substances (ALg) according to the equation

ALg 'A g ** ^ 3 * ^ 3 * turbidity proportional to turbidity (ALg) according to the relation ALg = Ag, where: A ^ = measured absorbance of ultraviolet radiation of a certain wavelength (L ^), ranging from 195 to 240 nm;

Ag = measured absorbance of ultraviolet radiation of different wavelength (Lg) in the range of 195 to 350 nm;

Ag «measured absorbance of visible radiation of wavelength (Lg) in the range of 430 to 600 nm;

k _lt kg, kg = factors determined for a given type of water, correcting the influence of the organic and turbidity component in the calculation of the absorbance values AL ^ and ALg.

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Another characteristic is that the specific values of nitrates, dissolved organic substances, expressed as chemical oxygen demand, turbidity - based on SiOg - ▼ values mg / 1, are determined according to

NO ₃ = AL ^. F _x

COD = AL ₂ . F ₂ turbidity (SiO ₂ ) »ALg. Fg where: F ^ = conversion factor, type of water of interest, in mg / l;

F ₂ = conversion factor, water type examined, in mg / l;

Fg »conversion factor, water type examined, SiO ₂ in mg / l.

empirically determined for currently relevant for conversion to NO ₃ empirically determined for simultaneously relevant for conversion to COD empirically determined for simultaneously relevant for conversion to content

According to the invention, the water to be examined flows through the cell or is at rest therein.

An embodiment of the method according to the invention is described as follows:

Water with natural organic pollution and turbidity is analyzed, as is the case with most natural waters.

The sample under investigation is radiated / concurrently emitted by ultraviolet radiation at wavelength = 220 nm, Lg = 254 nm and visible radiation at wavelength Lg = 546 nm.

According to the nature of the above water, the correction factors k ^, k ₂ , k ₃ were determined, namely the correction factor k ^, whose value in the case is k ^ = 2.55; correction factor kg, whose value in the case is kg = 1.50; correction factor kg, the value of which is kg »2.20 in this case.

Empirically determined empirically determined water types are used to convert the absorbances calculated according to the proposed relationships to specific values of nitrates, chemical oxygen demand _and turbidity.

256 419 conversion factors Fp Fg, Fg, of which F ^ is the conversion factor relevant for the conversion to NOg in mg / l; Fg is the conversion factor relevant to the conversion to COD in mg / l and Fg is the conversion factor relevant to the conversion to SiOg content in mg / l.

For a given type of water, the following specific values were found empirically: F ^ = 17; Fg = 40; F3 * 300

The following absorbances were measured:

For radiation with a wavelength L ^ «220 for radiation with a wavelength Lg = 254 for radiation with a wavelength Lg = 546 For absorbance proportional to nm concentration A ^ - 1,392 nm Ag ³² 0,370 nm Ag ³ 0,060 nitrates AL ^:

^AL 1 ^{= A} 1 - ( ^A 2 ~ ^A 3 * ^k 3 ^ ^k 2 " ^A 3 ^{, k} l * ^so F ^r ° given case AL ₁ = 1,392 - (0,370 - 0,06. 2,2). 5 - 0.06, 2.55 s = 0.862;

for absorbance proportional to the concentration of dissolved organic substances ALg:

ALg = Ag - Ag.kg, so for this case ALg = 0.370 - 0.0.60. 2.20 = 0.238;

for the absorbance proportional to the haze value of ALg: ALg = Ag, so ALg = 0.060 for the case.

The content of each component in mg / l is then:

NO x = AL _X. F ₁ = 0.882. 17 to 14.99 mg / L;

COD = ALg. Fg = 0.238. 40 = 9.52 mg / L;

turbidity (SiOg) = ALg. Fg = 0.060. 300 = 18.0 mg / L;

AND

Of course, this example does not exhaust the possibilities of the process according to the invention.

The process according to the invention allows a continuous control of the water in question, without the need for separate and laborious analyzes, in a single system. It creates good prerequisites for the use of automated devices of continuous registration or signaling.

Claims (4)

Method for determining the content of nitrates, dissolved organic substances and turbidity of water, especially surface, underground and drinking water, characterized in that ultraviolet radiation with a wavelength (Lg) lying in the range from 195 to 240 nm, ultraviolet radiation with a wavelength (Lg) lying in the range 195 to 350 nm but different from the wavelength Lg, and visible radiation of the wavelength (Lg) lying in the range 430 to 600 nm and the absorbance (A, A ', Ag) of these radiation are sensed and measured, wherein the absorbance proportional to the nitrate concentration (ALg) is determined by relation ALg = Ag - (Ag - Ag.kg) · ^k 2 ~ ^A 3 * ^k l 'absorbance proportional to the concentration of dissolved organic substances (ALg) according to ALg - A 1 - Ag. kg j absorber proportional to turbidity (ALg) according to the relation ^AL 3 ^{= A} 3 · where Ag = measured absorbance of ultraviolet radiation of a certain wavelength (Lg), lying in the range of 195 to 240 nm; Ag = measured absorbance of other wavelength (Eg) ultraviolet radiation in the range of 195 to 350 nm; Ag = measured absorbance of visible radiation of wavelength (Lg) in the range from 430 to 600 nm; kg, kg, kg = factors determined for a given type of water, correcting the effect of organic and turbidity components in the calculation of the absorbance values ALg and ALg. 2. Method according to claim 1, characterized in that the specific values of nitrates, dissolved organic substances, expressed as chemical oxygen demand, of the haze - based on SiOg in mg / l are determined according to the formula NOg = ALg. Fg COD * ALg. Fg turbidity SfOx = ALg. Fg, - 6 256 419 where β conversion factor, empirically determined for the type of water currently investigated, relevant for conversion to ΝΟθ in mg / l; Fg = conversion factor, empirically determined for the type of water currently investigated, relevant for conversion to COD in mg / l; Fg = conversion factor, empirically determined for the currently investigated water type, relevant for the conversion to SiOg content in mg / l. 3. A method according to claim 1, wherein the water to be examined flows through the cuvette. 4. The method of claim 1, wherein the test water is at rest in the cuvette. Printed by Moravian printing works, center. 11 100, the class of People's Militia 3, Olomouc