CN201047827Y - Chemical oxygen demand testing apparatus - Google Patents

Abstract

The utility model provides a chemical oxygen demand detector, which comprises a sample pond which is used for the holding of sewage sample to be tested, which can be drilled through by ultraviolet ray; an ultraviolet ray source that is used for emitting ultraviolet rays; an optical splitter that is used for the light splitting of the ultraviolet rays penetrating the sample pond; an ultraviolet light intensity detector that is used for the intensity of ultraviolet lights with varied wavelength; a data processor is used for the calculation of chemical oxygen demand according to the intensity of varied wavelength lights sent by the ultraviolet light intensity detector. What is known from the above technical scheme that the broad spectrum ultraviolet ray measuring method adopted by the utility model enables the measured result to represent the COD value with accuracy in a relatively wide application range; thereby reducing the measurement errors.

Description

Device for detecting chemical oxygen demand

Technical field

The utility model relates to a kind of chemical oxygen demand (COD) (being called for short COD) pick-up unit, especially a kind of device that shines and undertaken by spectral analysis the COD detection with ultraviolet ray.

Background technology

Chemical oxygen demand (COD) (COD) is meant the method for expressing of oxygen equivalent of the organic contaminant of available chemical method oxidation in the water, represents with mg/L.Chemical oxygen demand (COD) has reflected the degree that polluted by reducing substances, and reducing substances comprises organism, nitrite, ferrous salt, sulfide etc. in the water.It is very general that water body organism pollutes, and therefore, chemical oxygen demand (COD) also is one of index of organism relative content in the water (pollution level of water).

Measure CO D method can be passed through chemical method (as permanganimetric method, Chong Chrome acid potassium method) and uv analysis method in the prior art, but the COD detecting instrument of existing employing uv analysis method, being based on single wavelength ultraviolet ray measures, because the organic matter component kind complexity in the sewage, not all organism all produces a certain specific wavelength and absorbs, therefore, carry out the COD detection with the ultraviolet ray of single wavelength and can't comprehensively reflect the COD value accurately.

The utility model content

The purpose of this utility model provides a kind of device for detecting chemical oxygen demand, can improve the accuracy that COD detects carry out the COD detection in big spectral range.

For achieving the above object, the utility model provides a kind of device for detecting chemical oxygen demand, comprising:

Be used to hold the sample cell of the ultraviolet transmissive of sewage sample to be measured;

Be used for ultraviolet light source to described sample cell emission ultraviolet beam;

Be used to receive the ultraviolet beam of the transmission of described ultraviolet light source emission, and carry out the optical splitter of light-splitting processing by sample cell;

Be used to receive and detect the ultra violet intensity detecting device of the light intensity of intrafascicular each wavelength light beam of ultraviolet after the described optical splitter light-splitting processing;

Be used for calculating the data processor of chemical oxygen demand (COD), be connected with described ultra violet intensity detecting device according to the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output.

As shown from the above technical solution, the utility model adopts the ultraviolet measurement method of multi-wavelength, makes measurement result accurately to reflect the COD value in bigger range of application, has reduced measuring error.

Below by drawings and Examples, the technical solution of the utility model is described in further detail.

Description of drawings

Fig. 1 is the device for detecting chemical oxygen demand synoptic diagram of the utility model embodiment 1;

Fig. 2 is the synoptic diagram of optical splitter in the device for detecting chemical oxygen demand of the utility model embodiment 1;

Fig. 3 is the device for detecting chemical oxygen demand synoptic diagram of the utility model embodiment 2;

Fig. 4 is chemical oxygen demand (COD) and the biological aerobic amount detecting device synoptic diagram of the utility model embodiment 3.

Embodiment

Embodiment of the present utility model utilizes the organism that contains in the sewage that the principle of the absorption of ultraviolet is carried out COD to detect, the organism that contains in the sewage meets Lambert-Beer's law to the absorption of ultraviolet, just contains organic concentration in the sewage and is directly proportional with its absorbance.Different organism is different to the absorbance log of the ultraviolet light of different wavelength, according to the ultraviolet absorbance of organism to different wave length, can choose the bigger several ultraviolet wave band of each organic absorbance as detecting wave band, because the organic absorbance and the organic concentration at each selected wave band place all meet Lambert-Beer's law, so in some selected wave bands, carry out UV scanning, then the numerical value that obtains after the numerical integration that scanning wave band internal absorbance is carried out with in this wave band, produce the organic total concentration that absorbs and meet Lambert-Beer's law equally.The integrated value of the absorbance that in certain selected wave band ultraviolet light is produced according to sewage calculates the COD value.

Common organic pollutant composition complexity in the water body, comprise following kind, as petroleum hydrocarbon, palycyclic aromatic, nitrobenzene, phenyl amines, phenols, benzene series thing, volatile phenol etc., these materials generally all have absorption at ultraviolet band, absorption region is positioned at 200-400nm, the absorption spectra and the absorption coefficient of several organic correspondences for example, have been shown in the table one.

Table one

The organism title	Absorption spectra (nm)	Absorption coefficient
			Grip diene altogether	200-250	10000
Unsaturated aldehyde ketone	200-250	10000
			Aromatic rings	260-300	200-1000
Ketone, aldehyde	290	20-100

The absorptivity of the chromophoric group of majority of organic pollutants can be found, for consult less than part, utilize ultraviolet spectrophotometer (for example can adopt the Lambda-900 type) to measure.In the measuring method of ultra-violet absorption spectrum, as long as compound has the identical skeleton that adds lustre to, the wavelength X max of its absorption peak and absorption coefficient ε max are much at one.

In ultraviolet absorption spectroscopy, under wavelength selected, the relation of the concentration of absorbance and material, the absorption law Lambert-Beer's law of available light is described: when a monochromic beam passed transparent medium, the reduction of light intensity was directly proportional with the number of extinction particulate in the thickness of absorbing medium and the light path.With mathematic(al) representation be:

I/I ₀=10 ^-abcOr A=-1gI ₀/ I=abc (1)

Wherein, A is an absorbance, I ₀It is the incident light intensity; I is the transmission light intensity; A is an absorptivity; B is the distance that light passes through transparency, generally is the thickness (for determined value) of absorption cell, its unit with centimetre, c is the concentration of measured matter, the g.L of unit ^-1

Following formula can be write as again:

A＝εbc (2)

Wherein, ε is a molar absorptivity, and c is volumetric molar concentration (mol/L), if the unit of b is centimetre that then the unit of ε is Lmol ^-1Cm ^-1

In containing the solution of multiple extinction material, because each extinction material all has absorption to the monochromatic light of a certain wavelength, if each extinction particle is separate, their extinction ability can not influence each other, then the total absorbance of system equals each component absorbance sum, and promptly absorbance has additive properties:

$A=\underset{i}{\mathrm{\&Sigma;}}{A}_i={\mathrm{\&epsiv;}}_1{\mathrm{bc}}_1+{\mathrm{\&epsiv;}}_2{\mathrm{<figure-callout\; id="2"\; label="bc"\; filenames="Y20072014968700211.png"\; state="\{\{state\}\}">bc</figure-callout>}}_2+\&CenterDot;\&CenterDot;\&CenterDot;+{\mathrm{\&epsiv;}}_n{\mathrm{bc}}_n---\left(3\right)$

Wherein, ε ₁-ε _nThe molar absorptivity of each material, c ₁-c _nBe the volumetric molar concentration (mol/L) of each material, when the monochromatic light of a certain wavelength during by a kind of like this solution that contains multiple extinction material, the total absorbance of solution at this single wavelength place equals the absorbance sum of each extinction material.This rule is called the additive property of absorbance.And the total absorbance of solution at this wavelength place can calculate acquisition according to formula (1) by after measuring this monochromatic incident intensity and output intensity.

Absorption to ultraviolet light mainly is owing to the chromophoric group that exists in the organism, the number of the different carbon atoms that chromophoric group comprised is different, and the number of the carbon atom that chromophoric group comprised is directly related with COD, the experimental conclusion that draws, when the organism that only comprises in the solution with the kind chromophoric group, the absorbance that the COD value of solution and this organism produce at a certain wavelength place is linear, that is, and and COD ₁=k ₁ε ₁Bc ₁=kA ₁(c wherein ₁For comprising organic concentration, needn't distinguish concrete organism concentration separately, wherein k at this with the kind chromophoric group ₁Value can be measured by experiment and determine), according to the character of integration, in that on a certain wave band absorbance to be carried out the COD value of the integrated value that obtains after the numerical integration and solution linear equally.And according to the additive property principle of absorbance, when the organism of the chromophoric group that has a plurality of kinds, the absorbance that organism produced that comprises different types of chromophoric group has additive property, therefore, above-mentioned linear relationship is equally applicable to comprise the organic solution of multiple chromophoric group, but because the absorbance difference that all kinds of chromophoric groups produce ultraviolet light in different-waveband (mainly is because due to the absorptivity difference of all kinds of chromophoric groups in different-waveband, as shown in Table 1, in the wave band of 200-250nm, the absorptivity of gripping diene and unsaturated aldehyde ketone altogether is 10000, and aromatic rings and ketone, aldehyde etc. are to the almost not influence of ultraviolet light of this wave band), if only adopting the ultraviolet ray of single wavelength measures, its precision must be restricted, and can't reflect COD value actual in the sewage.Therefore, drawback for fear of the single wavelength detection, the wave band of choosing should cover the wave band that all organism in the sewage can produce bigger absorbance, carry out absorbance measuring at this wave band, utilize on this wave band the linear character of COD value that absorbance is carried out the integrated value that obtains after the numerical integration and solution to calculate COD (COD=k * A again _Jf, wherein k will determine by experimental measurement, A _JfBe the integrated value of at this wave band absorbance being carried out obtaining after the numerical integration).

In the measuring process of reality, in order further to improve precision, choose several ultra violet intensities and be absorbed bigger ultraviolet wave band (can learn) by ultraviolet spectrum analysis to sewage, carry out absorbance measuring.Each wave band is weighted the COD that read group total goes out last sewage, formula specific as follows:

COD＝k1×Ajf1+k2×Ajf2……+k×Ajfn (4)

In the following formula, n is the number of the ultraviolet wave band chosen, Ajf1-Ajfn carries out the integrated value that obtains after the numerical integration for each wave band to absorbance, k1-kn can measure by the following method, extract sewage sample to be measured, utilize the chemical method of standard to carry out the COD measurement, then the sample to be tested thin up is made that each material concentration is original half, (the at present domestic method that generally adopts is: potassium dichromate method, coulometric titration, rapid sealing oxidizing process, energy-conservation heating, chlorine correction method etc. to use the chemical method of standard again.Wherein, potassium dichromate method is national category-A standard method, can be used as the chemical method of the standard in the present embodiment) carry out COD and measure, continuation is diluted sample, and carry out COD with the chemical method of standard and measure, through the repeatedly measurement of sample dilution and chemical method, just can obtain m equation (m is the summation of the number of the diluted sample after original sewage sample and the dilution), solve k1-kn value in the formula (4) by this m equation, wherein m can be less than n, can utilize computing machine to adopt the algorithm of iteration that system of equations is found the solution, the initial value that estimation or the experiment by theory provides k1-kn.Because the organic components of the sewage that each factory discharges is basicly stable, pass through said method, the sewage that the k1-kn value that obtains is discharged for this factory has repeatability, therefore, trying to achieve the back at k1-kn just can utilize ultraviolet ray in above-mentioned selected wave band, sewage to the discharging of this factory is monitored in real time, with monitoring and the value of the Ajf1-Ajfn that obtains after calculating be updated in the formula (3), thereby obtain real-time COD value.

Measure in order accurately to carry out COD, if the organic composition in the sewage changes a lot, for example, the organic composition of different factory's dischargings is not quite similar, the sewage that a new factory discharges is measured, need redefine the measurement wave band according to the method described above, and redefine the k in the formula (4) ₁-k _nEmbodiment 1

Further introduce COD pick-up unit of the present utility model below by embodiment, as shown in Figure 1, the device for detecting chemical oxygen demand that the utility model embodiment 1 provides comprises:

The sample cell 1 of ultraviolet ray transmissive is used to hold sewage sample to be measured;

Ultraviolet light source 2 is used for to described sample cell emission ultraviolet beam; This ultraviolet light source can specifically can adopt the ultraviolet deuterium lamp as ultraviolet light source for the ultraviolet light source of emission 200-400 nanometer ultraviolet ray light beam.

Optical splitter 3 is used for the ultraviolet beam of transmission by sample cell carried out light-splitting processing;

Ultra violet intensity detecting device 4 is used to detect the light intensity of each wavelength light beam of ultraviolet beam after the light-splitting processing, specifically can adopt CCD, is preferably line array CCD.

Data processor 5 is used for calculating chemical oxygen demand (COD) according to the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output.

In above-mentioned optical splitter, can come ultraviolet beam is carried out light-splitting processing by blazed grating, ultraviolet beam is separated in the space according to wavelength, generate a series of wavelength of pressing and arrange ultraviolet beams.The concrete structure of this optical splitter can wherein, in order to make compact conformation, be saved the space as shown in Figure 2, and what adopt among Fig. 2 is reflective blazed grating, in addition, also comprises in optical splitter:

Entrance slit 31 is used for converting the ultraviolet beam of transmission by sample cell to long and narrow ultraviolet beam;

Off-axis paraboloidal mirror 32 is used for described long and narrow ultraviolet reflection to reflective blazed grating 33, and the ultraviolet beam of reflective blazed grating 33 reflected backs is reflexed to a catoptron 34;

Described catoptron 34 is used for the ultraviolet beam of described reflective blazed grating reflected back is reflexed to described ultra violet intensity detecting device.

The light that is sent by the ultraviolet deuterium lamp is behind the via flow sample cell, enter in the optical splitter, light is through the entrance slit of optical splitter, enter optical splitter, in optical splitter, by reflective blazed grating incident beam is separated in the space according to wavelength, with its frequency spectrum according to linear expansion, pass through a mirror reflects at a series of wavelength arrangement ultraviolet beams of pressing of the generation behind the space development to ultraviolet CCD at exit end, the last different pixel correspondence of CCD light beams of different wavelengths, just can obtain the ultraviolet light intensity of different wave length by the detected light intensity of CCD pixel on the collection diverse location.

Data processor 5 is data processing centre (DPC)s of whole device, cross the light intensity of clear water and the absorbance that the detected light intensity of CCD pixel is calculated each wavelength according to the ultraviolet (uv) transmission of prior detection, on selected wave band, the absorbance of each wavelength is carried out numerical integration then, in integrated value substitution formula (4), k wherein ₁-k _nDetermine by prior experiment, just can calculate the COD value of current water sample like this by formula (4).

May further include of data processor 5 as lower unit, to realize calculating the data processing of COD:

The absorbance computing unit is used for calculating according to the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output the absorbance of each wavelength;

The absorbance integral unit is connected with described absorbance computing unit, and being used on selected wave band to be measured with the wavelength is integration variable, and absorbance is carried out numerical integration, calculates absorbance integrated value on each wave band to be measured;

The chemical oxygen demand (COD) computing unit is connected with described absorbance integral unit, is used for according to absorbance integrated value on each wave band to be measured, and the linearly dependent coefficient chemistry oxygen demand of the integrated value of each wave band absorbance to be measured and chemical oxygen demand (COD).

Embodiment 2

As shown in Figure 3, present embodiment is on the basis of embodiment 1, has added the monitoring device of ultraviolet light source and sewage is carried out the device of turbidimetry.

Because may there be fluctuation in ultraviolet light source, and the result of fluctuation will inevitably cause the fluctuation of the ultra violet intensity after the transmission, and is accurate in order to make measurement result, needs to remove this light-intensity variation by the data processing place to go.Therefore, can set up ultraviolet light source monitoring device 11, be used to monitor the fluctuation situation of the luminous power of described ultraviolet light source, generate the fluctuation data, and send to described data processor, described data processor is revised the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output according to described fluctuation data, calculates chemical oxygen demand (COD) according to the light intensity of each wavelength of revised ultraviolet beam.

In addition, the sewage turbidity also can exert an influence to measurement result, because materials such as the silt in the water produce decay to ultraviolet ray equally, ultra violet intensity after the reduction transmission, in order to make measurement result accurate, also need to remove because material such as silt produces in the water to ultraviolet absorption by data processing.Therefore, set up the turbidity monitoring device, being used for sewage sample to be measured to the sample cell of ultraviolet transmissive carries out turbidity and detects, and detected turbidity sent to described data processor, described data processor is revised the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output according to described turbidity, calculates chemical oxygen demand (COD) according to the light intensity of each wavelength of revised ultraviolet beam.

As shown in Figure 3, this turbidity monitoring device can specifically comprise:

Visible light source 121, be used for to described ultraviolet ray thoroughly sample cell shine visible light;

Visible light light intensity detector 122 is used to detect transmission and crosses the ultraviolet ray light intensity of the visible light of sample cell thoroughly;

Turbidity processor 123 is used for calculating turbidity according to the light intensity of the detected visible light of described visible light light intensity detector;

Utilize visible light to carry out under the situation of turbidimetry, requiring the described ultraviolet ray same transmissive visible light of sample cell thoroughly.

Need to prove, turbidity monitoring device and ultraviolet light source monitoring device can be arranged in the device of the present utility model separately, also can be arranged on (as shown in Figure 3) in the device of the present utility model simultaneously, when being provided with simultaneously, described data processor is revised the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output according to described turbidity and described fluctuation data, calculates chemical oxygen demand (COD) according to the light intensity of each wavelength of revised ultraviolet beam.

Embodiment 3

Present embodiment is the further expansion to above-mentioned two embodiment, and on the basis of the device for detecting chemical oxygen demand on the basis that above-mentioned two embodiment provide, the relevant peripheral hardware of configuration is to adapt to real time automatic detection.

As shown in Figure 4, it is the structural representation of embodiment 3, comprising:

The sampling weir 6 that is communicated with blow-off line;

Water tank 7 is communicated with the sample cell of described sampling weir and described ultraviolet transmissive, is used to hold the sewage to be measured of continuous sampling.And can carry out precipitation process to the sewage of gathering, the purpose of continuous sampling is in order better to reflect the time situation of tested sewage, for example, sewage to the discharging of a certain factory detects, equal proportion sampling by continuous a period of time (for example 1 hour), after the precipitation mixing through water tank, can reflect the actual conditions of the sewage of this factory preferably.After the sewage to be measured of the collection in the water tank collects predetermined amount, through precipitation, just can offer ultraviolet ray thoroughly sample cell carry out COD measurement.

Can also comprise a pump 8 (being specifically as follows membrane pump), described sampling weir and water tank can be communicated with described pump intake piping road by outlet bypass line separately, and the sample cell of described sampling weir, water tank and ultraviolet transmissive can be communicated with described delivery side of pump pipeline by inlet bypass line separately;

On the outlet bypass line of described sampling weir and water tank, valve can be provided with, also valve can be provided with in the inlet bypass line of the sample cell of described sampling weir, water tank and ultraviolet transmissive.

For whole device is kept clean, be convenient to clean, this device can also comprise a washwater tank 9, be used to hold the cleaning fluid that cleans whole device, this washwater tank is communicated with described pump intake piping road by the outlet bypass line, and the outlet bypass line of described washwater tank is provided with valve.

Above-mentioned valve can be opened control by computing machine for solenoid valve, and the transfer of the liquid in the whole device is finished in the unlatching by solenoid valve and the cooperation of pump.

In the application of reality, the device of present embodiment is mainly finished following workflow:

Sampling: when needs begin to sample, computer control starts pump 8 and solenoid valve V1, V4 open, water sample enters water tank, variation according to liquid level gauge in the water tank, whether the water sample of determining pump 8 extractions reaches determined value (in order to measure the COD value of sewage more accurately, need be to the sewage that flows be carried out continuous sampling, generate sewage sample to be measured, determined value herein is the sewage sample total that predefined needs adopt acquisition continuously), if reached determined value, then close pump 8 and solenoid valve V1, V4.

Measure: when needs measure CO D, computer control starts pump 8 and solenoid valve V3, V6, and sewage water sample to be measured enters ultraviolet ray sample cell thoroughly, begins to measure.

Clean: when the needs detergent line, computer control starts pump 8 and solenoid valve V5, V6, and cleaning fluid (generally adopting clear water to get final product) enters ultraviolet ray sample cell thoroughly, and beginning detergent line and ultraviolet ray be sample cell thoroughly.Also can clean water tank by control pump 8 and solenoid valve.

Carry out the method for on-line determination COD of sewage by the said equipment, have the reaction time short, be easy to real-time monitoring, measuring accuracy height, non-secondary pollution, advantage such as easy to use.

Further specifying the COD measuring process of enforcement of the present utility model below by concrete experimentation and experimental data, is measurand at the sewage of having selected certain factory's discharging.

Step 1, in the sample cell of ultraviolet transmissive, add clear water, measure the light intensity of clear water;

Step 2, selected sewage to be measured, sewage to be measured is sampled, after the water sample sedimentation 2h that gathers, become different concentration ratio (establishing the sample that symbiosis becomes m variable concentrations ratio) with distilled water diluting again, and carry out synchronously with the chemical oxygen demand (COD) (COD) of chemical determination water sample;

Step 3, water sample is scanned, measure its waveform, and the position of absorption peak, determine that the stronger wave band of UVA is as wave band to be measured;

The water sample of step 4, the different proportion after will diluting, join respectively in the sample cell of ultraviolet transmissive, the degree of depth of the water sample that adds is identical with the degree of depth that adds clear water, respectively the water sample of each adding is measured then, light intensity after measuring ultraviolet (uv) transmission on the wave band that step 3 is selected, measure the light intensity (as incident intensity) of the clear water that records in the integrating step 1, obtain the absorbance that goes up each wavelength place of selected wave band, and on selected wave band, absorbance is carried out numerical integration;

In the integrated value substitution formula (4) of step 5, the absorbance that will record to the water sample of different proportion after the dilution, form multiple regression equation, wherein m is the number of the water sample of the different proportion after diluting, and n is the ultraviolet wave band number of choosing that is used to measure, the COD in the separate equation ₁-COD _nBe the COD value that records with chemical method, k ₁-k _nBe scale-up factor, be the amount to be asked in the equation, A _Jf11-A _JfmnWhen measuring for the sample after each dilution is carried out the ultraviolet ray irradiation, the integrated value after the absorbance to this wave band on each selected wave band is carried out numerical integration.Multiple regression equation is as follows:

COD ₁＝k ₁×A _jf11+k ₂×A _jf12……+k _n×A _jf1n

COD ₂＝k ₁×A _jf21+k ₂×A _jf22……+k _n×A _jf2n

……

COD _m＝k ₁×A _jfm1+k ₂×A _jfm2……+k _n×A _jfmn (5)

(can estimate by theory earlier or the mode of test provides k with the method for iteration ₁-k _nInitial value) above-mentioned regression equation (5) is found the solution, draw k ₁-k _n

Step 6, obtaining k ₁-k _nAfter, the just device that can utilize the utility model embodiment to provide is monitored in real time to the sewage of this factory's discharging, and after the integrated value of the absorbance of the correspondence that records above-mentioned definite wave band, substitution formula (4) is because k ₁-k _nKnown, just can directly try to achieve the COD value, thereby reach the purpose of real-time monitoring.

Certain pharmaceutical factory's high concentration:

The accuracy check:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				97.88	63.306	-34.574	-34.97
101.51	65.312	-35.698	-35.27
				265.06	211.646	-33.414	-12.65
235.53	212.108	-24.222	-10.24

Certain pharmaceutical factory's low concentration:

The accuracy check:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				14.45	11.16	-3.29	-22.93
14.90	10.06	-4.84	-30.44
				35.40	37.90	2.60	7.37
32.95	37.887	4.93	14.96

Certain printing and dyeing mill's high concentration, the scanning wavelength scope of choosing is 380-240nm:

The accuracy check:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				106.39	94.33	-12.06	-11.4415
246.19	244.418	-1.77	-0.72
				108.39	95.226	-13.16	-12.13
243.09	242.389	-0.70	-0.29

Certain printing and dyeing mill's high concentration, the scanning wavelength scope of choosing is 650-240nm:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				104.39	105.352	0.96	0.91
247.69	249.444	1.80	0.73
				107.49	108.736	1.25	1.15
245.09	247.327	2.28	0.94

Certain printing and dyeing mill's low concentration:

The accuracy check:

Chemical method COD value	This method COD value	Absolute error	Relative error
				6.78	5.93	-	-12.5
6.58	5.83	-0.75	-11.6
				14.21	14.275	0.07	0.40
11.85	14.082	2.23	18.7

Certain Acrylic Fibers Plant high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				274.26	268.239	-6.021	-2.19
276.96	279.609	2.649	0.95
				643.62	565.034	-78.586	-12.21
626.35	583.443	-42.907	-6.85

Certain acrylic fibers low concentration, the scanning wavelength scope of choosing is 650-270nm:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				315.19	294.346	-20.84	-7.10
308.95	286.827	-22.12	-7.69
				694.45	692.091	-2.36	-0.34
671.01	688.683	17.67	2.64

Certain acrylic fibers low concentration, the scanning wavelength scope of choosing is 380-240nm:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				308.95	281.414	-27.536	-8.88

696.45	696.223	-2.227	-0.32
				774.61	781.434	6.824	0.881
947.11	904.569	-42.541	-4.48

Certain municipal sewage plant's low concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				7.1	4.086	-3.014	-41.29
6.48	3.6	-2.88	-43.77
				14.05	11.741	-2.309	-15.34
13.64	12.314	-1.326	-9.58

Certain municipal sewage plant's high concentration:

The accuracy check:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				42.63	35.826	-6.804	-16.75
36.18	33.487	-2.693	-7.24
				97.27	85.545	-11.725	-11.81
92.07	88.324	-3.746	-4.16

Certain washing low concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				9.16	3.787	-5.373	-58.15
7.74	5.604	-2.136	-27.24
				17.63	18.377	0.747	4.01
16.2	17.217	1.017	5.91

Certain washing high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				17.98	4.601	-14.179	-74.70
22.7	4.631	-17.209	-79.30
				35.74	32.578	-3.162	-8.87

33.16

34.251

1.091

3.39

Certain beer high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				223.79	320.212	96.422	42.89
227.72	318.254	90.534	40.02
				151.37	213.187	61.817	40.86
519.74	557.224	37.484	7.21

Certain feed ditch high concentration 600-200nm:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				28.32	33.66	5.43	19.8
56.81	55.085	-1.72	3.09

Certain feed ditch high concentration 380-200nm:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				26.02	41	14.98	59.8
28.33	41.113	12.783	46.7
				62.13	66.341	4.211	6.67
54.81	65.634	10.824	19.3

Certain smelts high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				6.62	7.983	1.36	20.9
6.23	7.964	1.73	28.2
				14.4	12.486	-1.91	-13.4
12.91	12.291	-0.62	-4.83

Certain ethene low concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				38.71	50.22	11.51	29.8
40.64	45.128	4.49	11.1
				98.95	106.042	7.09	7.71
95.47	102.086	6.62	6.94

Certain ethene high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				184.57	213.79	29.22	15.9
186.11	210.471	24.36	13.2
				435.25	446.646	11.40	2.62
427.46	444.404	16.94	3.95

Certain petrochemical plant low concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				14.11	13.883	-0.23	-1.73
12.52	13.843	1.32	11.5
				28.26	26.367	-1.89	-6.75
28.62	25.943	-2.57	-9.04

Certain petrochemical plant high concentration:

The check of accuracy:

Chemical method COD value	This method COD value	Absolute error	Relative error %
				106.87	113.624	6.75	6.26
104.18	117.192	13.01	12.4
				232.02	198.983	-32.04	-13.7
230.86	200.615	-30.2	-13.0

Can add up according to above data processing:

Sample	Mistake	10%≤mistake	Mistake	Number
					I8	12	6 groups	17	35

COD

26

11 groups

6 groups

43

By above data as can be seen: testing result is that the scanning curve of water sample at sewage treatment plant inflow mouth place is good, and absorbance has 80% between 0.2-1.0 in wavelength selected.And its related coefficient height, the coefficient R of seven enterprises is arranged ²Greater than 0.99, and remaining is also near 0.99.Have only the absorbance of water inlet of acrylic factory high and its related coefficient is lower.This may be that accidental error causes, and repetitive operation is repeatedly measured and can be reduced this error, and related coefficient is increased.

At the scanning curve of the water sample in sewage treatment plant exit, its absorbance does not have regularity at the wavelength selected internal absorbance.This is with the scanning wave band of the scanning wave band of water delivering orifice and water inlet is identical a relation in order to allow.And related coefficient is not very desirable, reason may be that the COD value of a lot of water samples is lower than the range of linearity of chemical determination, and the kind of the chemical substance of water sample is many, complicated component is the synthesis of the water sample of a lot of workshops bio-refractory, it is the material that the chemical method difficulty is cleared up greatly that the organism of these difficult degradations has, and this experimental technique is highly sensitive to the mensuration of these water samples.Equally for the water sample of acrylic plant effluent mouth, its COD value height, the peak value of response is big, has reached 3 at wavelength selected internal absorbance mxm. (change 3 into, i.e. A=3), and the COD value reaches 1500mg/L.

It should be noted that at last: above embodiment is only in order to explanation the technical solution of the utility model but not limit it, although the utility model is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that: it still can make amendment or be equal to replacement the technical solution of the utility model, and these modifications or be equal to replacement and also can not make amended technical scheme break away from the spirit and scope of technical solutions of the utility model.

Claims (11)

1. a device for detecting chemical oxygen demand is characterized in that, comprising:

Be used to hold the sample cell of the ultraviolet transmissive of sewage sample to be measured;

Be used for ultraviolet light source to described sample cell emission ultraviolet beam;

Be used to receive the ultraviolet beam of the transmission of described ultraviolet light source emission, and carry out the optical splitter of light-splitting processing by sample cell;

Be used to receive and detect the ultra violet intensity detecting device of the light intensity of intrafascicular each wavelength light beam of ultraviolet after the described optical splitter light-splitting processing;

Be used for calculating the data processor of chemical oxygen demand (COD), be connected with described ultra violet intensity detecting device according to the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output.

2. device according to claim 1 is characterized in that, described optical splitter comprises:

The transmission that the described ultraviolet light source that is used for receiving is launched separates in the space according to wavelength by the ultraviolet beam of sample cell, generates a series of wavelength of pressing and arranges ultraviolet beam, and send to the reflective blazed grating of described ultra violet intensity detecting device.

3. device according to claim 1 is characterized in that, described optical splitter comprises:

Be used for the transmission that the described ultraviolet light source of incident is launched is converted to by the ultraviolet beam of sample cell the entrance slit of long and narrow ultraviolet beam;

Be used for to be converted to the off-axis paraboloidal mirror that long and narrow ultraviolet beam reflects;

Be used for ultraviolet beam, in the space, separate, generate a series of ultraviolet beams that wavelength is arranged of pressing, and the reflective blazed grating of described off-axis paraboloidal mirror is given in reflection according to wavelength with described off-axis paraboloidal mirror reflection;

Be used for a series of ultraviolet beams of arranging by wavelength with described off-axis paraboloidal mirror reflected back and reflect catoptron to described ultra violet intensity detecting device.

4. device according to claim 1 is characterized in that, also comprises:

Be used to monitor the fluctuation situation of the luminous power of described ultraviolet light source, generate the fluctuation data, and send to the ultraviolet light source monitoring device of described data processor, be connected with described data processor; Described data processor is revised the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output according to described fluctuation data, calculates chemical oxygen demand (COD) according to the light intensity of each wavelength of revised ultraviolet beam.

5. device according to claim 1 is characterized in that, also comprises:

Being used for sewage sample to be measured to the sample cell of ultraviolet transmissive carries out turbidity and detects, and detected turbidity is sent to the turbidity monitoring device of described data processor, be connected with described data processor, described data processor is revised the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output according to described turbidity, calculates chemical oxygen demand (COD) according to the light intensity of each wavelength of revised ultraviolet beam.

6. device according to claim 5 is characterized in that, described turbidity monitoring device comprises:

Be used for to the described ultraviolet ray visible light source of sample cell irradiation visible light thoroughly;

Be used to detect transmission and cross the ultraviolet ray visible light light intensity detector of the light intensity of the visible light of sample cell thoroughly;

Be used for calculating the turbidity processor of turbidity according to the light intensity of the detected visible light of described visible light light intensity detector;

Described ultraviolet ray is sample cell transmissive visible light thoroughly.

7. device according to claim 1 is characterized in that, described ultra violet intensity detecting device is a line array CCD.

8. device according to claim 1 is characterized in that, described ultraviolet light source is the ultraviolet light source of emission 200-400 nanometer ultraviolet ray light beam.

9. device according to claim 1 is characterized in that data processor comprises:

Be used for calculating the absorbance computing unit of the absorbance of each wavelength according to the light intensity of each wavelength of the ultraviolet beam of ultra violet intensity detecting device output;

Being used on selected wave band to be measured with the wavelength is integration variable, and absorbance is carried out numerical integration, calculates the absorbance integral unit of absorbance integrated value on each wave band to be measured, is connected with described absorbance computing unit;

Be used for according to absorbance integrated value on each wave band to be measured, and the chemical oxygen demand (COD) computing unit of the linearly dependent coefficient chemistry oxygen demand of the integrated value of each wave band absorbance to be measured and chemical oxygen demand (COD), be connected with described absorbance integral unit.

10. device according to claim 1, it is characterized in that, the sampling weir that also comprise a pump, is communicated with, be used to deposit the water tank of the sewage to be measured of sampling with blow-off line, described sampling weir and water tank are communicated with described pump intake piping road by outlet bypass line separately, and the sample cell of described sampling weir, water tank and ultraviolet transmissive is communicated with described delivery side of pump pipeline by inlet bypass line separately;

The outlet bypass line of described sampling weir and water tank is provided with valve, also is provided with valve in the inlet bypass line of the sample cell of described sampling weir, water tank and ultraviolet transmissive.

11. device according to claim 10, it is characterized in that, also comprise a washwater tank, be used to hold the cleaning fluid that cleans whole device, this washwater tank is communicated with described pump intake piping road by the outlet bypass line, and the outlet bypass line of described washwater tank is provided with valve.

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