CN101329251B - Device for detecting chemical oxygen demand and biologic oxygen demand - Google Patents

Abstract

The invention relates to a detection device used for detecting chemical oxygen demand and biological oxygen demand, comprising a sampling barrage which is communicated with a sewage pipeline, a water storage tank which is used for storing the sewage sample to be detected after sampling, a constant-temperature aeration device which is used for storing the sewage sample to be detected at constant temperature and carry out the continuous aeration of the stored sewage sample to be detected, a sample pool which can be transmitted by ultraviolet ray and is used for storing the sewage sample to be detected during the irradiation process of the ultraviolet ray, an ultraviolet light source, a light splitter which is used for carrying out the spectro-disposal of ultraviolet beam which passes through the sample pool, an ultraviolet light intensity detector and a data processor. The detection device of the invention used for detecting chemical oxygen demand and biological oxygen demand shortens the detection time of COD and BOD, facilitates the realization of real-time monitoring and improves the detection precision.

Description

Chemical oxygen demand (COD), biological aerobic amount detecting device

Technical field

The present invention relates to a kind of chemical oxygen demand (COD) (being called for short COD) and BOD (being called for short BOD) pick-up unit, especially a kind of device that shines and carry out the detection of COD and BOD by spectral analysis 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) 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, carrying out the COD detection with the ultraviolet ray of single wavelength can't comprehensive and accurate reflection COD value.

BOD (being called for short BOD) is an important indicator of environmental monitoring and water pollution control, has reflected the concentration that can not use the pollutant of chemical method oxidation in the water.1912 by the proposition of the wastewater treatment council of Britain imperial family. and the standard testing of using till today in countries in the world analytical approach-BOD5 method, need under 20 ℃ of conditions of constant temperature, measure 5 days forward and backward dissolved oxygen DOs (DO) through 5 days biological cultivations. calculate its difference and obtain BOD5.Its value is subjected to water sample composition (when particularly noxious material exists), pH value, the influence of temperature, culture environment condition, time, factor such as nitrated.At present, the detection method of BOD5 brings many groups difficult to practical application, especially in engineering management of sewage disposal and pollution source monitoring.Owing to needed 5 days to go out data, can't adapt to field control and closed loop adjustment, more can not carry out the on-line continuous monitoring.

In recent years, BOD5 determining instrument and fast measuring instrument, method are carried out a large amount of investigations both at home and abroad, proposed many new equipment new methods: 1, Hua Boshi respirometer; 2, electric coulombmeter; 3, differential pressure gauge; 4, DO instrumental method, 5, the microbial film oxygen electrode method; 6 aeration type oxygen electrode methods.The 1-4 quasi-instrument still needs 20 ℃ of cultivations of 5 days constant temperature, has just used instrumental method when DO tests instead.The 5th quasi-instrument is used the oxygen electrode be covered with microbial film. and be a kind of rapid assay methods, but film is extremely tender and lovely, serviceable life short (about 3-7 days) and influence is used.The 6th quasi-instrument all has product both at home and abroad. and adopt the area integral of oxygen electrode METHOD FOR CONTINUOUS DETERMINATION biological sludge D0 change curve in the sewage biochemical reaction process to ask for BOD5, after the oxygen conversion coefficient converts, get the BOD value.Measure fast.Be applicable to the field control analysis, existing problems are that it is bigger to influence the quadrature error because sample introduction front and back D0 equilibrium value changes. poor repeatability. and different dilute concentration sewage sample introduction integrations are disproportionate, and the BOD linearity is not high, the high-concentration sewage test duration is long, and it is time-consuming to ask for the oxygen conversion coefficient.

BOD5 has obtained using widely as an overall target of organic pollutants in the water body.This method has reaction comparatively really to organic pollutants degree in surface water, sanitary sewage and the commonly industrial wastewater.But there are serious shortcomings and deficiencies in this method: 1, minute reaches 1, is unsuitable for on-the site analysis, can not instruct and control the wastewater treatment of industrial and mining enterprises; 2, operating conditions harshness keeps the constant temperature in 5 days comparatively difficult; 3, to the mensuration of the pollution level that contains the hardly degraded organic substance pollutant effluents, its result is significantly less than actual value.

The method of taking aspect the current research of measuring at BOD is both at home and abroad examined pressure type coulombmeter method, direct manometry with ining addition again.Oxygen electrode method, nephelometry, microbiological sensor method or the like, the subject matter that these methods exist is: 1, measure under airtight cultivation conditions, dissolved oxygen DO in the culture apparatus constantly reduces and can not get replenishing, hinder metabolism breeding and the organic degraded of microorganism, thereby can not truly reflect the pollution level of organic wastewater; 2, part adopts the BOD determination method of electrode, can not be suitable for the mensuration of high-concentration waste water, and electrode life is short simultaneously.Therefore must research a kind of simple and easy, fast and more accurately assay method reflects organic pollution level in the waste water more truly.

In addition, do not occur in the prior art can realizing quickly and easily, simultaneously the equipment that the COD and the BOD of sewage detected yet.

Summary of the invention

The purpose of this invention is to provide a kind of chemical oxygen demand (COD) and biological aerobic amount detecting device,, improve COD, BOD detection efficiency and accuracy, and detect when realizing COD and BOD to shorten the detection time of C0D, BOD.

For achieving the above object, the invention provides a kind of chemical oxygen demand (COD) and biological aerobic amount detecting device, comprising:

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

Water tank is communicated with described sampling weir, is used to deposit the sewage sample to be measured that obtains after the sampling;

The constant temperature aerator is communicated with described water tank, is used for depositing described sewage sample to be measured with stationary temperature, and the sewage sample to be measured that it is deposited is continued aeration;

The sample cell of ultraviolet ray transmissive is communicated with described water tank and constant temperature aerator, is used for the process in the ultraviolet ray irradiation, holds sewage sample to be measured;

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

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

The ultra violet intensity detecting device is used to detect the light intensity of each wavelength light beam of the ultraviolet beam after the light-splitting processing;

First data processor 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;

Second data processor is connected with described first data processor, is used to calculate the difference of the chemical oxygen demand (COD) before and after the described sewage sample aeration to be measured, and the difference that obtains be multiply by behind the correction factor as BOD; Described correction factor is the BOD of the original water sample identical with described sewage sample composition to be measured measured with the detection method of the BOD of standard, with the ratio of the difference of the chemical oxygen demand (COD) of described original water sample aeration front and back; Chemical oxygen demand (COD) behind the described original water sample aeration is under constant temperature described original water sample to be continued aeration to measure after 1 to 4 hour, and the described constant temperature in the aeration process is a certain temperature value between 25 ℃-40 ℃.

As shown from the above technical solution, chemical oxygen demand (COD) of the present invention and biological aerobic amount detecting device have shortened COD, BOD weak point detection time, can realize real-time monitoring easily, have improved the accuracy of detection height.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Fig. 1 is the chemical oxygen demand (COD) and the biological aerobic amount detecting device synoptic diagram of the embodiment of the invention 1;

Fig. 2 is the synoptic diagram of the middle optical splitter of the embodiment of the invention 1;

Fig. 3 is the chemical oxygen demand (COD) and the biological aerobic amount detecting device synoptic diagram of the embodiment of the invention 2;

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

Embodiment

The equipment of the embodiment of the invention has been realized the measuring ability of COD and BOD simultaneously, before the checkout equipment of introducing the embodiment of the invention in detail, introduces the chemical oxygen demand (COD) of embodiment of the invention employing and the detection method and the detection principle of BOD earlier.

The detection method of the BOD of the embodiment of the invention, the mode of employing constant temperature aeration has shortened Measuring Time, comprises the steps:

Measure the COD of sewage sample to be measured;

Described sewage to be measured is placed a thermostatic tank, and described sewage to be measured continued the aeration (sewage that component is different, its aeration time may have difference, specifically can determine according to test, generally can be 1 to 4 hour), after aeration finishes, the COD of the described sewage sample to be measured behind the measurement aeration, described constant temperature is a certain temperature value between 25 ℃-40 ℃; The temperature value of described constant temperature should guarantee that the organism in the water can be rapidly divided by microorganism and take off, and don't as for kill microorganisms, the temperature value of constant temperature is preferably 30 ℃, and the time that continues aeration is preferably 2 hours.

It is poor to calculate the sewage sample COD to be measured and the COD behind the aeration that record before the aeration, and the difference that obtains be multiply by behind the correction factor as BOD.

Wherein above-mentioned correction factor can be determined in the following way:

Choose the essentially identical water sample identical as original water sample, measure the BOD of described original water sample with the detection method of the BOD of standard (for example, BOD5 etc.) with sewage sample composition to be measured;

Measure the COD of described original water sample;

Described original water sample was placed a constant temperature 1 to 4 hour, and described original water sample continued aeration, after aeration finishes, measure the COD of the described original water sample behind the aeration, described constant temperature is a certain temperature value between 25 ℃-40 ℃;

The COD and the COD behind the aeration that calculate the original water sample that records before the aeration are poor;

The ratio of difference of the detection method of described BOD with standard being measured the COD of the original water sample that records before the BOD of described original water sample and the aeration and the COD behind the aeration is as described correction factor.

Because it is to continue and process slowly that microorganism is decomposed organism in the sewage, even if under higher constant temperature, continue aeration, take off also very difficult all organism are all divided, therefore, COD difference before and after the aeration is less than actual BOD, but the numerical value that can obtain according to the detection method of the BOD of standard is revised, when detecting the essentially identical sewage of composition once more, (for example detect the sewage of same factory discharging) like this, just can be under identical constant temperature and aeration time, the BOD that carries out that utilizes correction factor accurately to repeat has in real time detected.

Introduce the detection method of the chemical oxygen demand (COD) of embodiment of the invention employing below in detail, this detection method is independently being carried out the COD detection and all will used when carrying out the BOD detection.

Embodiments of the invention are to utilize 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:

$A=\underset{i}{\mathrm{\&Sigma;}}{A}_i={\mathrm{\&epsiv;}}_{1}b{c}_1+{\mathrm{\&epsiv;}}_2\mathrm{<figure-callout\; id="2"\; label="b\; c"\; filenames="S071B9005620070710E000011.png,S071B9005620070710E000031.png"\; state="\{\{state\}\}">b</figure-callout>}{c}_{}{}_2+\&CenterDot;\&CenterDot;\&CenterDot;+{\mathrm{\&epsiv;}}_{n}b{c}_n---\left(3\right)$

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＝k ₁×A _jf1+k ₂×A _jf2......+k×A _jfn (4)

In the following formula, n is the number of the ultraviolet wave band chosen, A _Jf1-A _JfnFor each wave band carries out the integrated value that obtains after the numerical integration, k to absorbance ₁-k _nCan 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 measurement of dilution of sample repeatedly and chemical method, just can obtain m equation (m be original sewage sample and dilute after the summation of number of diluted sample), solve k in the formula (4) by this m equation ₁-k _nValue, 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, and estimation or experiment by theory provide k ₁-k _nInitial value.Because the organic components of the sewage that each factory discharges is basicly stable, by said method, the k that obtains ₁-k _nThe sewage that value is discharged for this factory has repeatability, therefore, and at k ₁-k _nTry to achieve the back and just can utilize ultraviolet ray in above-mentioned selected wave band, the sewage of this factory's discharging is monitored in real time, with the A that obtains after monitoring and the calculating _Jf1-A _JfnValue 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 _n

Embodiment 1

Further introduce chemical oxygen demand (COD) of the present invention and biological aerobic amount detecting device below by embodiment, as shown in Figure 1, chemical oxygen demand (COD) that the embodiment of the invention 1 provides and biological aerobic amount detecting device comprise:

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

Water tank 7 is communicated with the sewage sample to be measured that obtains after being used to sample with described sampling weir; 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 and measure, also can provide and supply with the constant temperature aerator and carry out the processing of constant temperature aeration.

Constant temperature aerator 10 is communicated with described water tank, is used for depositing described sewage sample to be measured with stationary temperature, and the sewage sample to be measured that it is deposited is continued aeration; This constant temperature aerator can be made of thermostatic tank and air pump.

The sample cell (can be cuvette) 1 of ultraviolet ray transmissive is communicated with described water tank and constant temperature aerator, is used for the process in the ultraviolet ray irradiation, holds sewage sample to be measured;

Ultraviolet light source 2 is used for to described sample cell emission ultraviolet 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 the ultraviolet beam after the light-splitting processing;

First data processor 51 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;

Second data processor 52 is connected with described first data processor, is used for calculating BOD according to the chemical oxygen demand (COD) before and after the described sewage sample aeration to be measured.

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.

First data processor 51 and second data processor 52 are data processing centre (DPC)s of whole device, first data processor is crossed 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 that detects in advance, 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).Second data processor utilizes the COD result of calculation of first data processor when carrying out the BOD detection, calculate the BOD value

May further include of first data processor 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 output 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);

Described second data processor comprises:

The BOD computing unit, be connected with described chemical oxygen demand (COD) computing unit, be used to write down the chemical oxygen demand (COD) of the described sewage sample to be measured in aeration front and back, and the work of the chemical oxygen demand (COD) of described sewage sample to be measured before and after the aeration is poor, export as BOD after the difference that obtains be multiply by correction factor.

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 first data processor, described first 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 first data processor, described first 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 invention separately, also can be arranged on (as shown in Figure 3) in the device of the present invention simultaneously, when being provided with simultaneously, described first 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 the foregoing description provides, 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, can also comprise a pump 8 (being specifically as follows membrane pump), described sampling weir, constant temperature aerator 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, constant temperature aerator, 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, constant temperature aerator 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, constant temperature aerator 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 connected 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 open and close control by computing machine for solenoid valve, and the transfer of the liquid in the whole device is finished in the keying 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, sewage 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 setting value, then close pump 8 and solenoid valve V1, V4.Simultaneous computer control starts opening of pump 8 and solenoid valve V1, V8, and sewage flows into the constant temperature aerator, after the sewage water sample arrival predetermined value for the treatment of to gather in the constant temperature aerator, and the beginning aeration.

Measure: the COD of the sewage water sample before needs are measured aeration or only carry out COD when detecting, 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.

After aeration finished, computer control started pump 8 and solenoid valve V7, V6, and the sewage water sample behind the aeration enters ultraviolet ray sample cell thoroughly, began to carry out COD and measured.

COD value before and after the aeration is poor, multiply by correction factor then, obtain the BOD value of sewage to be measured.

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 and constant temperature aerator by control pump 8 and solenoid valve.

Carry out the method for on-line determination COD of sewage and BOD 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.

In an embodiment of the present invention, adopting the detection method of the COD of multiwave ultraviolet ray scanning is the detection basis of BOD, further specifying the COD measuring process of embodiments of the invention 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 embodiment of the invention 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	-11.44
246.19	244.418	-1.77	-0.72
				108.39	95.226	-13.16	-12.13
243.09	242.389	-0.70	-0.2910

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	The mistake mistake	10%≤mistake	The 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 technical scheme of the present invention to be described but not limit it, although the present invention 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 technical scheme of the present invention, 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 solution of the present invention.

Claims (11)

1. chemical oxygen demand (COD) and biological aerobic amount detecting device is characterized in that, comprising:

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

Water tank is communicated with described sampling weir, is used to deposit the sewage sample to be measured that sampling obtains;

The constant temperature aerator is communicated with described water tank, is used for depositing described sewage sample to be measured with stationary temperature, and the sewage sample to be measured that it is deposited is continued aeration;

The sample cell of ultraviolet ray transmissive is communicated with described water tank and constant temperature aerator, is used for the process in the ultraviolet ray irradiation, holds sewage sample to be measured;

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

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

The ultra violet intensity detecting device is used to detect the light intensity of each wavelength light beam of the ultraviolet beam after the light-splitting processing;

First data processor 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;

Second data processor is connected with described first data processor, is used to calculate the difference of the chemical oxygen demand (COD) before and after the described sewage sample aeration to be measured, and the difference that obtains be multiply by behind the correction factor as BOD; Described correction factor is the BOD of the original water sample identical with described sewage sample composition to be measured measured with the detection method of the BOD of standard, with the ratio of the difference of the chemical oxygen demand (COD) of described original water sample aeration front and back; Chemical oxygen demand (COD) behind the described original water sample aeration is under constant temperature described original water sample to be continued aeration to measure after 1 to 4 hour, and the described constant temperature in the aeration process is a certain temperature value between 25 ℃-40 ℃.

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

Reflective blazed grating is used for described ultraviolet beam according to wavelength in the space separately, generates a series of wavelength of pressing and arranges ultraviolet beam.

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

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

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

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

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

The ultraviolet light source monitoring device, be used to monitor the fluctuation situation of the luminous power of described ultraviolet light source, generate the fluctuation data, and send to described first data processor, described first 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:

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 first data processor, described first 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:

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

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

The turbidity processor is used for calculating 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 for can launch the ultraviolet light source of containing 200-400 nanometer ultraviolet ray light beam.

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

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) and output;

Described second data processor comprises:

The BOD computing unit, be connected with described chemical oxygen demand (COD) computing unit, be used to write down the chemical oxygen demand (COD) of the described sewage sample to be measured in aeration front and back, and the chemical oxygen demand (COD) of described sewage sample to be measured before and after the aeration is poor, export as BOD after the difference that obtains be multiply by correction factor.

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

Pump, described sampling weir, water tank and constant temperature aerator are communicated with described pump intake piping road by outlet bypass line separately, and the sample cell of described sampling weir, water tank, constant temperature aerator 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, constant temperature aerator 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, constant temperature aerator 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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