GB2490537A - Non-contact absorbance measurement - Google Patents
Non-contact absorbance measurement Download PDFInfo
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- GB2490537A GB2490537A GB1107538.9A GB201107538A GB2490537A GB 2490537 A GB2490537 A GB 2490537A GB 201107538 A GB201107538 A GB 201107538A GB 2490537 A GB2490537 A GB 2490537A
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- wastewater
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- 238000011481 absorbance measurement Methods 0.000 title description 2
- 238000000034 method Methods 0.000 claims abstract description 39
- 239000002351 wastewater Substances 0.000 claims abstract description 36
- 238000002835 absorbance Methods 0.000 claims abstract description 33
- 238000005259 measurement Methods 0.000 claims abstract description 26
- 239000007787 solid Substances 0.000 claims abstract description 13
- 230000003287 optical effect Effects 0.000 claims description 12
- 239000010865 sewage Substances 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical group N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 8
- 238000004065 wastewater treatment Methods 0.000 claims description 5
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical group [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims description 4
- 229910021529 ammonia Inorganic materials 0.000 claims description 4
- 239000006260 foam Substances 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 238000005070 sampling Methods 0.000 claims description 3
- 238000005273 aeration Methods 0.000 claims description 2
- 239000001272 nitrous oxide Substances 0.000 claims description 2
- 239000010802 sludge Substances 0.000 claims description 2
- 230000005855 radiation Effects 0.000 claims 1
- 239000011368 organic material Substances 0.000 abstract description 2
- 239000007791 liquid phase Substances 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000012544 monitoring process Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000013459 approach Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000002028 Biomass Substances 0.000 description 2
- 238000000862 absorption spectrum Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000010841 municipal wastewater Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000004886 process control Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 235000013365 dairy product Nutrition 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000004519 grease Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012457 nonaqueous media Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000002572 peristaltic effect Effects 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 238000002211 ultraviolet spectrum Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
- G01J3/427—Dual wavelengths spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
- G01N21/51—Scattering, i.e. diffuse reflection within a body or fluid inside a container, e.g. in an ampoule
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/85—Investigating moving fluids or granular solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/18—Water
- G01N33/1806—Biological oxygen demand [BOD] or chemical oxygen demand [COD]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N2021/8411—Application to online plant, process monitoring
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- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Immunology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Biodiversity & Conservation Biology (AREA)
- Biomedical Technology (AREA)
- Emergency Medicine (AREA)
- Molecular Biology (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A method for determining the absorbance of a scattering medium by measuring the scattered light at two or more wavelengths can be used to measure the organic load of wastewater without direct sensor contact with the wastewater and measures the UV absorbance due to dissolved organic material and infers the organic load. Scattered light from particulates is measured at the wavelength where the absorbance is to be measured, and at a reference wavelength where the scattered light is affected by the suspended solids in the sample but remains stable when the organic load changes. The absorbance and hence organic load for a wastewater can be determined from the two scattered light measurements by empirical calibration. The method is intended to be applied to the measurement of a flowing wastewater sample in a channel or tank.
Description
NON-CONTACT ABSORBANCE MEASUREMENT
This invention relates to the measurement of the absorbance characteristics of a liquid, solid or gas sample by an optical non-contact method.
Industrial processes frequently require monitoring of one or more key parameters which characterise the quality of the process material, for example the turbidity or colour of a beverage. Many of these measurements are made rapidly and continuously by online process analysers rather than waiting for the results of sampling the process material and making the measurements off line in a laboratory.
Some process materials are particularly difficult to handle such as sewage, dairy products or molten metals and this has given rise to non-contact measurement techniques which seek to make the measurement whilst avoiding direct contact between the measuring system and the process material. There may also be health and safety issues which make non-contact measurement desirable.
An example of such a process is the collection, treatment and discharge of wastewaters. Municipal sewage treatment plants and industrial wastewater treatment plants are required to reduce the polluting load of the waste to an agreed level prior to discharge, and will benefit from continuous measurement of some key pollution parameters such as suspended solids concentration, biochemical oxygen demand (BOD), chemical oxygen demand (COD) and ammonia concentration. Such data is of use both at the discharge of the plant, as a means of controlling the process and also at the inlet and within the collection network, where for example significant changes in the polluting load can notify operators of the need to adjust the aeration in the biological stage of the plant. The signals may be a data input to an automatic control system. This perceived need has been met by a range of monitoring instruments, some of which are dipped into a flowing channel; others pump a sample through a chemical analyser. The reliability of these instruments is badly affected by the direct contact with the wastewater sample which frequently blocks pipes or coats surfaces with layers of grease or biological films or dirt. Further these instruments are frequently complex machines so that the cost of monitoring the wastewater is high both in initial capital cost and the maintenance costs of keeping the instruments operating within acceptable accuracy. Many of these machines require supplies of services such as compressed air or mains water to assist in cleaning, thus incurring both installation and operating costs and restricting their application.
The present invention utilises the fact that dissolved organic mailer in wastewaters increases the absorbance in the UV portion of the spectrum. An example of a typical wastewater absorbance spectrum is shown in Figure 1. It may be seen that there is a rapid rise in absorbance as the wavelength shortens into the blue and ultraviolet region. Absorbance at 254 nm is commonly used as a surrogate for dissolved organic load in wastewaters. The UV absorbance reduces the amount of scattered UV light reaching the surface of the wastewater, and this effect can be detected and used to estimate the organic load of the wastewater.
To measure scattered light from a flowing sample, one possible method is to use the optical arrangements described in EP 1241464 which can acquire scattered light data from the wastewater by non-contact means. Whereas EP 1241464 uses scattered light to infer the suspended solids of the wastewater and fluorescence to infer the organic load of the wastewater, the present invention uses scattered light intensity at different wavelengths to infer both the dissolved and particulate parts of the organic load of the wastewater.
Referring to Figure 2, incident light (1) is refracted at the wastewater surface (2) and penetrates the wastewater (3). As the refracted light (4) passes through the wastewater light some of it is scattered upwards (5) and is collected by lens (6) and produces a response upon detector (7). Both the refracted light (4) and the scattered light (5) are subject to attenuation by the wastewater. Figure 3 shows an alternative arrangement where the detector is arranged at an angle to the vertical. This has the advantage of a more compact instrument compared with Figure 2, and has been found to work belier. An advantage of the arrangement of Figure 3 over Figure 2 is that for direct specular reflection to occur at the sample surface due to waves and turbulence, the liquid surface in Figure 3 has to change further from the horizontal wave-free condition. The steeper the angle required of a wave, the less likely this is to occur. No ideal angle combination has been found. There is a trade-off to be had between reducing the effect of waves, and the losses upon passing through the liquid surface, which increase as the angles of the incident light (1) and the scattered light received by the detector (6) with the vertical increase.
ln addition to the wavelength-dependent absorbance of the liquid phase of the wastewater, there may also be a wavelength-dependent effect associated with the scattering of light by the suspended particles. As the particle size approaches the wavelength of the light, and for smaller particles, the effect is very strong, enhancing the scattering of shorter wavelengths. The particle sizes in typical municipal wastewaters cover a very wide range from colloidal material up to millimetres in size.
The present invention uses at least two wavelengths to interrogate the wastewater.
One or more wavelengths are needed which respond to the attenuation of UV and blue light in the liquid phase and one or more wavelengths which are scattered by the particulates in the wastewater sample, but which are not subject to variable attenuation in the liquid phase. A suitable wavelength for the UV scattered light is in the range 270 -280 nanometres. The choice is based upon two considerations: it is desirable to use the longest possible wavelength as this provides the best optical and detection efficiency; data on the UV spectra of known biodegradable organic substances present in wastewater and recent academic work on wastewater fluorescence properties confirm that absorbance at 270-280 nanometres is indicative of organic load in municipal wastewaters. A suitable wavelength where the liquid phase attenuation is constant is 1300 nanometres where the attenuation is about 1.0 absorbance units over a 10 millimetre path length in pure water. Additional absorbance due to the dissolved pollutants present in wastewater would be unusual at this wavelength and variations in scattered light intensity are normally due to changes in the particulate phase only. It is beneficial to choose a wavelength where the liquid phase attenuation is comparable with the attenuation in the UV due to the organic pollutants, as then the UV and reference scalier light will penetrate a similar amount into the sample and comparisons of their optical behaviour are valid.
Absorbances of filtered wastewater samples are typically 0.5 absorbance units over a millimetre path at 270-280 nm. A further consideration in wavelength selection for the reference wavelength is to avoid reflected light from the floor of the tank or channel carrying the sample. An absorbance of for example 0.1 units per 10 millimetre path would restrict the system to operation in channels and tanks of at least 0.5 metres depth.
In use the method described in EP1241464B1 may be followed to determine the suspended solids of the sample. The UV absorbance is derived from the ratio of the scattered light at the UV wavelength or other wavelength where varying liquid phase absorbance occurs, and the wavelength with fixed liquid phase absorbance, plus the suspended solids level of the sample which affects the behaviour at both wavelengths. This may be understood graphically referring to Figure 4. Figure 4 shows a theoretical model of the way in which the detected scattered light varies with absorbance due to liquid phase material, and absorbance due to particulates. Line (1) represents the behaviour of the suspended solids measurement where the liquid phase absorbance is fixed. By measuring the light intensity received, corrected for range to sample, the absorbance due to the solids can be inferred, and from this the suspended solids determined. If line (2) represents the relative light intensity received, the absorbance due to particulates is 0.5. If the relative scattered light intensity for the UV source (normalised now for source power) is greater and corresponds to line (3), the absorbance due to liquid phase absorbance can now be read off from line (4) as 0.7 absorbance units. This can then be interpreted as an organic load due to the dissolved organic material. The theoretical model of Figure 4 assumes that the light scattering behaviour is the same for the two wavelengths used. This is at best an approximation, and an adjustment based upon empirical or theoretical considerations may be needed. For a complex suspension such as a wastewater, an empirical approach to calculating the absorbance and hence the organic load is likely to be more efficient than a theoretical one, as a theoretical approach would require detailed particle size data and an integration across the particle size range. The absorbance may be modelled as a sum of for example exponential or polynomial components with the coefficients determined by empirical data to give the best fit.
The method described may be used to determine the concentration of other absorbing species present in wastewaters, for example dyes or nitrate.
The method has been developed for use with electromagnetic radiation, but it could also be used with other waves such as ultrasound and in non-aqueous media.
A particular issue with applying the non-contact method on existing wastewater treatment sites is that there may be no suitable access point to view the wastewater surface. An alternative method of presenting the sample which still uses the optical non-contact method can be applied. Referring to Figure 5, the sample is pumped into a tank (1) with the instrument (2) mounted above it so that a view of the surface (3) is available. The sample is pumped into the inlet (4) and under the baffle (5) which acts to debubble the sample and then over the weir (6) which maintains the sample level.
The weir (6) has a drain hole (7) sized to match the pumped pipework to enable solids settling in the tank to reach the outlet (8). The pump must be sized to provide sufficient flow for the level to reach the top of the weir and effectively to pass through the drain hole (7). A useful feature of the design is that in the absence of sufficient flow from the pump, the level in the tank will fall and this can be detected by the optical unit (2) or by a separate level sensor (9).
The non-contact principle can be extended to additional sensors mounted in a sampling system. Referring to Figure 6, a closed tank (1) is filled by a reversible pump (2), for example a peristaltic type, through inlet pipe (3) and fills the tank (1) until it overflows back to the process through the outlet pipe (13). For this operation valve (4) is closed and valves (5) and (14) are open. In this manner, the non-contact optical load monitor (7) is able to measure the sample load by interrogating the sample through the free sample surface (7). The tank (1) can be used to generate a headspace for gas phase measurement, valve (5) is closed, valve (4) is opened, and pump (2) is reversed. This effectively seals the headspace with the wastewater sample and provides for mixing. Headspace sensor (8) may then be used to monitor for example hydrogen sulphide or general volatile organics using an electronic nose sensor. Sensors (9) and (10) can be used to measure the optical absorbance of the headspace for example nitrous oxide. Of particular interest in wastewater treatment is the ammonia concentration which can be measured in the headspace by the addition of alkali using dosing pump (11) from the reagent reservoir (12) to raise the pH. Sensors (9) and (10) would then measure the absorbance spectrum across the headspace in the deep ultraviolet region and calculate the sample ammonia concentration. When measurement is complete valve (5) may be opened, valve (4) closed, valve (14) opened and tank (1) emptied. The process may then be repeated if valve (4) is closed and valves (5) and (14) are open and the pump (2) returned to forward operation to fill the tank (1) again. The system may be used to provide a continuous measurement from the optical non-contact sensor (7) with periodic headspace measurement, or may be operated as a series of batch measurements with all sensors. Other configurations of pumps, vessels and valves are possible to enable combined headspace and optical non-contact measurements.
For wastewater applications feeding forward into an activated sludge process control system, a settled sewage measurement is needed. This can be made directly on an open channel, a flow-splitting chamber or other access to the mixed settled sewage flow. An alternative to measuring the mixed flow is to mount the non-contact monitor on the bridge(s) of primary settlement tanks. This has the advantage of providing settled sewage suspended solids measurements which can be used for monitoring and as part of an automated desludging system, or to balance flows between the tanks. The data can also give an indication of the scum or foam on the tank surface as a proportion of the tank area, as foam and scum give a very high signal to the non-contact monitor receiver. These signals are normally rejected but can be utilised as a scum or foam detector.
The method is also suited to use in the sewer network feeding into a sewage treatment works. The non-contact method provides reliability, and the method can be engineered for battery power where mains power is unavailable. The data may be used to feed forward into the process control system. With the extra advanced warning of load change provided from the sewer network, the treatment plant can take actions such as increasing the amount of biomass available for treatment. The method may also be used to monitor the quality of the intermittent discharges from combined sewer overflows.
Load monitoring is also valuable in protecting a sewage treatment works against very high loads, which can damage the biomass upon which treatment depends. Warning from an instrument in the sewer network or at the inlet to a works can enable plant operators or an automatic system to divert excessive loads to tanks and process the load at a rate which the plant can tolerate.
Claims (15)
- CLAIMS1. A method for measuring the absorbance of a scattering medium at a specific wavelength or range of wavelengths using measurements of the scattered radiation from the particulates in the medium made at the wavelength or range of wavelengths of interest and at a reference wavelength where the absorbance is known to be fixed.
- 2. A method as in claim 1 which measures the absorbance of a wastewater.
- 3. A method as in claim 1 which uses the scattered light data from the two wavelengths to determine the organic load of a wastewater.
- 4. A method as in claim 3 which is used as pad of an activated sludge plant aeration control system.
- 5. A method as is claim 3 which detects scum or foam due to its high signal level.
- 6. A method as in claim 2 which operates at a wavelength in the range 270-280 nanometres and at a wavelength of 1300 nanometres for the reference wavelength.
- 7. A method as in claim 2 which uses a sampling system to create a liquid surface for non-contact optical measurement.
- 8. A method as in claim 7 which combines the non-contact optical measurement with headspace measurements.
- 9. A method as in claim 8 in which the headspace measurement is ammonia.
- 10. A method as in claim 8 in which the headspace measurement is nitrous oxide concentration.
- 11. A method as in claim 8 in which the headspace measurement is volatile organics concentration.
- 12. A method as in claim 2 which measures wastewater load in an open channel or flow-splitting chamber on a wastewater treatment works.
- 13. A method as in claim 2 which measures wastewater load from a mounting on a rotating or stationary bridge over a primary settlement tank on a wastewater treatment works.
- 14. A method as in claim 13 which provides measurements of settled sewage suspended solids and organic load which are used for tank desludging automation.
- 15. A method as in claim 13 which provides measurements of settled sewage suspended solids and organic load which are used for tank flow balancing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1107538.9A GB2490537A (en) | 2011-05-06 | 2011-05-06 | Non-contact absorbance measurement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1107538.9A GB2490537A (en) | 2011-05-06 | 2011-05-06 | Non-contact absorbance measurement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201107538D0 GB201107538D0 (en) | 2011-06-22 |
| GB2490537A true GB2490537A (en) | 2012-11-07 |
Family
ID=44243683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1107538.9A Withdrawn GB2490537A (en) | 2011-05-06 | 2011-05-06 | Non-contact absorbance measurement |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2490537A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014202531A1 (en) * | 2013-06-16 | 2014-12-24 | Nielsen Ulrik Merrild | Detection of indications of psychoactive components in a liquid |
| WO2015070873A1 (en) * | 2013-11-13 | 2015-05-21 | Drugster Aps | Detection of substances in liquids, in particular psychoactive substances |
| US20210208067A1 (en) * | 2018-06-29 | 2021-07-08 | Hach Company | Suspended solids measurement of wastewater |
| RU2816661C1 (en) * | 2023-05-31 | 2024-04-02 | Федеральное бюджетное учреждение науки "Северо-Западный научный центр гигиены и общественного здоровья" | Method for determining content of volatile foul-smelling compounds in air from sludge beds |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4225233A (en) * | 1978-02-02 | 1980-09-30 | The Trustees Of Boston University | Rapid scan spectrophotometer |
| US5919707A (en) * | 1994-12-22 | 1999-07-06 | Nalco Chemical Company | Monitoring of rolling oil emulsions |
| EP1069426A1 (en) * | 1998-04-02 | 2001-01-17 | Hamamatsu Photonics K.K. | Method and device for measuring concentration of absorbing component of scattering/absorbing body |
| US6229612B1 (en) * | 1998-10-12 | 2001-05-08 | The Regents Of The University Of California | Paper area density measurement from forward transmitted scattered light |
| US20020086432A1 (en) * | 2000-12-28 | 2002-07-04 | Tam Lisa A. | Portable co-oximeter |
| EP1287333A1 (en) * | 2000-05-16 | 2003-03-05 | Jeacle Limited | Photometric analysis of natural waters |
-
2011
- 2011-05-06 GB GB1107538.9A patent/GB2490537A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4225233A (en) * | 1978-02-02 | 1980-09-30 | The Trustees Of Boston University | Rapid scan spectrophotometer |
| US5919707A (en) * | 1994-12-22 | 1999-07-06 | Nalco Chemical Company | Monitoring of rolling oil emulsions |
| EP1069426A1 (en) * | 1998-04-02 | 2001-01-17 | Hamamatsu Photonics K.K. | Method and device for measuring concentration of absorbing component of scattering/absorbing body |
| US6229612B1 (en) * | 1998-10-12 | 2001-05-08 | The Regents Of The University Of California | Paper area density measurement from forward transmitted scattered light |
| EP1287333A1 (en) * | 2000-05-16 | 2003-03-05 | Jeacle Limited | Photometric analysis of natural waters |
| US20020086432A1 (en) * | 2000-12-28 | 2002-07-04 | Tam Lisa A. | Portable co-oximeter |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014202531A1 (en) * | 2013-06-16 | 2014-12-24 | Nielsen Ulrik Merrild | Detection of indications of psychoactive components in a liquid |
| US10281392B2 (en) | 2013-06-16 | 2019-05-07 | Drugster Aps | Detection of indications of psychoactive components in a liquid |
| WO2015070873A1 (en) * | 2013-11-13 | 2015-05-21 | Drugster Aps | Detection of substances in liquids, in particular psychoactive substances |
| US20210208067A1 (en) * | 2018-06-29 | 2021-07-08 | Hach Company | Suspended solids measurement of wastewater |
| US11906426B2 (en) * | 2018-06-29 | 2024-02-20 | Hach Company | Suspended solids measurement of wastewater |
| RU2816661C1 (en) * | 2023-05-31 | 2024-04-02 | Федеральное бюджетное учреждение науки "Северо-Западный научный центр гигиены и общественного здоровья" | Method for determining content of volatile foul-smelling compounds in air from sludge beds |
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| GB201107538D0 (en) | 2011-06-22 |
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