DE102012112541A1 - Apparatus for optically monitoring parameter of aqueous liquid, has control- and evaluation device for programmable control of pump- and valve unit and is configured to evaluate readings determined by optical measuring arrangement - Google Patents

Abstract

The apparatus (100) has an optical measuring arrangement with one and another optical sensors, where one optical sensor has a light source emitting ultra-violet light, a photodetector and a measurement path extending between the light source and the photodetector. A pumping unit passes the fluid and cleaning fluid through a measuring chamber (121). A control- and evaluation device (112) is provided for programmable control of a pump- and valve unit and is configured to evaluate the readings determined by the optical measuring arrangement. An independent claim is included for a method for monitoring parameters of an aqueous liquid, particularly waste water.

Description

The invention relates to a device for monitoring parameters of an aqueous liquid, in particular wastewater, comprising a measuring chamber with a supply line for the liquid to be examined and a discharge, an optical measuring arrangement with at least one optical sensor for measuring at least one optical property of the liquid, and a Control and evaluation device. The invention further relates to a method for monitoring parameters of an aqueous liquid, in particular wastewater, using such a device.

For operational safety, the control of technological processes and the maintenance efficiency of water treatment plants, it is of great importance to monitor the clarification process at sufficiently short, periodic intervals on the basis of quality parameters that characterize the degree of contamination of waste water. In this way, it can be checked whether a system is working properly. Malfunction of the plant can lead to inadequate treatment of effluents, which in turn may affect the chemical, biological and environmental quality of waters into which the effluent is discharged after leaving the treatment plant. For this reason, it is a legal requirement in many states for sustainable and environmentally compatible use of water to comply with a specific technical standard, maintenance rules and limit values for wastewater treatment.

Using spectrophotometry, photometric readings of wastewater can be determined directly. These measured values can then be converted into specific wastewater parameters with the help of mathematical evaluation methods, which give an indication of the functionality of the processing plant. The measurement of the spectral absorption coefficient with UV light at a wavelength of 254 nm (SAK 254 [1 / m]) leads to the derivation of the COD (chemical oxygen demand) and BOD (biological oxygen demand), which are the most important parameters in wastewater analysis , The COD is an evaluation parameter for the total load of watercourses and wastewaters with organic compounds, including biologically heavy or non-biodegradable compounds. BOD is a relative parameter of the amount of oxygen consumed in the oxidative degradation of water constituents by the microorganisms present in the effluent within a specified time, usually 5 hours. The BOD is thus a parameter for biodegradable organic substances. In addition, the color of the water, such as DOC (dissolved organic carbon) can be characterized by the spectral absorption coefficient at a wavelength of 436 nm (SAK 436 [1 / m]), which also gives rise to the Huminstoffbelastung. The relationship between DOC and humic substances is well known to a person skilled in the art. The advantage of photometric wastewater analysis lies in the fact that the measurement process essentially requires no reagents and nevertheless provides reliable measured values.

Especially in sparsely populated regions, decentralized small wastewater treatment plants are used for wastewater treatment, as these regions often can not be connected to large municipal water treatment plants for technical or financial reasons. Small wastewater treatment plants require government-mandated controls to ensure that the plant is operating properly, as well as compliance with maintenance rules. The controls are usually carried out by the operator himself, as a regular inspection by maintenance and service companies is associated with ongoing costs due to the long travel distances.

For this reason, control devices based on the principle of spectrophotometry have been developed and with which important parameters of wastewater analysis can be continuously determined and monitored by the operator himself.

A device of the type mentioned is from the DE 10 2009 028 254 A1 become known, with the wastewater parameters such. B. nitrate or spectral absorption coefficient can be determined spectrophotometrically by a light beam is passed through a measuring chamber and detected. To carry out the reference measurement, a reference absorber in the form of a solid is introduced into the measuring chamber. The cleaning of the components is relatively cumbersome because not only the measuring chamber, but also the reference absorber must be cleaned regularly to avoid biofilm formation and to generate meaningful readings.

The GB 2 256 043 A discloses a control device including a channel through which the liquid to be examined flows and a plurality of sensors arranged along the channel, including optical sensors, for measuring liquid properties. Because of the channel occurring fluid turbulences it can be easier to fouling the channel inner walls. To compensate for the associated sensor drift, it is proposed to recalibrate the sensor at periodic intervals. A reference measurement is not performed, which results in the need for costly temperature compensation. The cleaning of the device is done manually.

The EP 0 724 718 describes a device for measuring properties of a liquid, the device including a channel through which the liquid flows and a plurality of sensors arranged along the channel, including optical sensors, for measuring the liquid properties. The cross-sectional shape of the channel changes depending on the respectively arranged sensor. For cleaning the channel, a device-consuming cleaning mechanism in the form of a moving along the channel spray head is provided.

The DE 102 28 929 A1 discloses an apparatus for the photometric measurement of the content of a chemical substance in a measuring solution, in particular for the measurement of nitrate and dissolved organic substances. The device has as a light source a flashlamp and two receiving units which receive the radiation transmitted through the measurement solution. The light of the flashlamp is regulated depending on the measured intensity values.

In the DE 10 2008 028 058 A1 describes a turbidity meter for the outlet of sewage treatment plants, which has an optical sensor for measuring the turbidity in the infrared range. The device also has UV LEDs to counteract the formation of biofilms in the measuring section of the turbidity meter by means of UV light.

The DE 10 2004 063 720 describes a control device for wastewater, which has a sensor by which a quality parameter of the waste water can be determined and transmitted as an electronic signal has.

The known devices are characterized by a relatively high expenditure on equipment, a complex measurement process and a complicated cleaning mechanism and require short maintenance intervals, which results in significant disadvantages in terms of their mobility, their cost and ease of use. In addition to the disadvantages mentioned above, the control devices currently available on the market for small wastewater treatment plant operators are very expensive to purchase.

There is therefore a need for a low-cost, easy-to-use and maintainable device for monitoring parameters of an aqueous liquid, in particular wastewater. The device should be based on a simple measuring method and in particular allow an operator of a small sewage treatment plant to perform the prescribed controls efficiently and to fix existing functional problems targeted, with low costs and in the short term. It is therefore an object of the invention to meet this need.

This object is achieved by a device as mentioned at the outset, which is inventively characterized in that the optical measuring arrangement comprises a first optical sensor and a second optical sensor, wherein the first optical sensor, a first light source which emits UV light, a first photodetector and a first measurement path extending between the first light source and the first photodetector, the second optical sensor having a second light source emitting visible light, a second photodetector, and a second measurement path extending between the second light source and the second photodetector, the first and the second measuring path extend through the measuring chamber and the liquid therein, the supply line or the discharge line has at least one valve means, through which at least one cleaning fluid can be fed into the measuring chamber, the device at least one pumping means for conducting the liquids or the at least one cleaning fluid through the measuring chamber, and the control and evaluation device is configured for the programmable control of at least the pump and valve means and for evaluating the measured values determined by means of the optical measuring arrangement.

Thanks to the invention, a monitoring device is provided with which parameters of an aqueous liquid, in particular wastewater, user-friendly and can be determined maintenance and cost-effective, so that the safe operation of water treatment plants, especially small sewage treatment plants, and the proper control of the technological processes taking place reliably becomes. The invention also facilitates the lawful implementation of legal requirements, especially for operators of small wastewater treatment plants. For Austria valid legal sources are after the current state, for example, the EU Water Framework Directive 2000/60 / EC , the Water Law and the Austrian Drinking Water Ordinance.

The term "aqueous liquid" as used herein refers primarily to all types of water such as sewage, river and lake water, technical process waters, as well as drinking water, mineral water and water, which is provided for drinking water production. In particular, however, the term refers to wastewater, the term "wastewater" also including purified waste water or clarified waste water (clear water).

The term "cleaning fluid" refers to reagents and cleaning agents that are suitable for preventing biofilm formation in the measuring chamber and in its supply and discharge lines. The cleaning fluid may be, for example, water, preferably optically pure water, distilled water, ion-free water, germ-free water, a disinfectant, alcohol or an osmotic solution, e.g. B. osmosis water with a conductivity of <20 μS, be.

The valve means for supplying the cleaning fluid is preferably arranged in the supply line. The cleaning fluid, (possibly also several different cleaning fluids) is located in a refillable cleaning container for the cleaning fluid and can be performed by means of the at least one pumping agent via the valve means from the cleaning container into the supply line and on through the measuring chamber and the discharge. To make the structure of the device as simple as possible, it is advantageous if only one type of cleaning fluid is provided.

If the valve means is arranged in the drain, then the cleaning fluid from the refillable cleaning container is guided by means of the pumping means via the valve means in the discharge and on through the measuring chamber in the supply line.

The device is normally anchored in the immediate vicinity of the sampling point for the aqueous liquid to be examined, for example, in the water inlet or drainage of a water management system. The device can be fixed, for example by means of cable ties or the like to existing components of the water management system. The supply line and, if appropriate, the discharge thereby dip into the body of water from which the liquid sample to be examined is taken. Preferably, the sample inlet opening of the supply line is arranged at a defined distance from the water surface. To comply with this distance can be attached to the supply line a float (float).

For the determination of the spectral absorption coefficient at a wavelength of 254 nm (SAK 254) of waste water, which is advantageously in accordance with the German standard method for the examination of water, waste water and sludge ( DIN 38404-3; current status: July 2005 ), it is useful if the first light source emits UV light with a wavelength of 254 nm and the second light source emits visible light with a wavelength of 550 nm. In this embodiment, the liquid in the measuring chamber is consequently illuminated with UV light at 254 nm and with visible light at 550 nm (to compensate for undissolved water constituents) and the transmitted light intensity is measured by means of the photodetectors and converted into an electrical signal. From the obtained intensity values the SAK 254 is calculated according to a known manner, from which in turn the COD and the BOD can be derived. The evaluation of the measurement results is carried out according to the invention by the control and evaluation and is explained in more detail below in the examples. For the determination of the SAK 254 of drinking water, the measurement at 550 nm is normally not necessary, since drinking water typically contains no undissolved constituents. In this case, the control and evaluation unit can be programmed so that only the measurement is performed at 254 nm and the measurement at 550 nm is omitted.

An advantageous development of the invention provides that the optical measuring arrangement has a third optical sensor which has a third light source emitting visible light, a third photodetector and a third measuring path extending between the third light source and the third photodetector, the third measuring path passes through the measuring chamber and the liquid therein. For the determination of the coloration of the liquid, which is characterized by the spectral absorption coefficient at a wavelength of 436 nm (SAK 436 in [1 / m]), it is therefore expedient for the third light source to emit visible light with a wavelength of 436 nm , The SAK 436 can also be used as a parameter for DOC and thus also for the Huminstoffbelastung.

The device can be implemented particularly easily if the first, the second and the third light source have a wavelength-specific LED (Light Emitting Diode). LEDs also have the advantage of longer life than the flashlamps otherwise commonly used in photometry. In a preferred embodiment, the LED of the first light source emits UV light of a wavelength of 254 nm and the LED of the second light source visible light of a wavelength of 550 nm. In addition, if a third optical sensor is provided, then it is advantageous if the LED of the first light source UV light of a wavelength of 254 nm, the LED of the second light source visible light of a wavelength of 550 nm and the LED of the third light source emitted visible light of a wavelength of 436 nm.

As an alternative to the UV LED, the first light source can also be a UV low-pressure lamp (eg from Heraeus Noblelight).

For reference measurements for calibration purposes or to compensate for temperature effects that are caused by the light sources, it is favorable if the control and evaluation device is set up to perform reference measurements based on the filled with cleaning fluid measuring chamber. In this embodiment, the cleaning fluid is used directly as a reference liquid and thereby allows a very simple and inexpensive apparatus design of the device according to the invention. At the time of the application DIN standard no. 38404-3 / July 2005 To perform appropriate zero measurement, it is useful if optically pure water is used as a cleaning fluid and thus as a reference liquid. Advantageously, it is about optically pure water of quality 1 after DIN ISO 3696 (Water for analytical purposes) which is prepared, for example, by soaking a membrane filter of 0.1 μm pore size for about 1 h in distilled or deionized water and then filtering about 1 liter of distilled or deionized water through the prepared filter.

In order to compensate for variations in the UV light intensity of the first light source, in a first advantageous development, a beam splitter is arranged between the first light source and the measuring chamber, which diverts a portion of the UV light emitted by the first light source into a reference measuring path and a reference photodetector supplies. The beam splitter is preferably realized as a semitransparent mirror. For example, approximately 30% of the light for the reference measurement is branched off into a reference measurement path and fed to a reference detector by the beam splitter.

As an alternative to the aforementioned development, which provides a beam splitter, fluctuations in the UV light intensity of the first light source occurring in another advantageous development can be compensated for advantageously if the control and evaluation unit is set up to detect the threshold voltage of the first photodetector and to be taken into account when evaluating the measured values.

The first, second and third photodetectors as well as the reference detector may each comprise a photoelectric element, in particular a photodiode, which generates an electrical signal corresponding to the detected light intensity and supplies this to the control and evaluation unit. Advantageously, the photodetectors used have the lowest possible bandwidth or are only sensitive to the corresponding wavelength. For example, the first photodetector and the reference detector may be of the type BPW21 (Siemens), the second photodetector of the type TW30SX (Texas Instruments) and the third photodetector of the type OSD15-5T (OSI Optoelectronics). The aforementioned detectors can also be followed by a known manner, a preamplifier for amplifying the electrical signal.

In order to be able to rule out erroneous measurements that occur due to excessive bandwidth, it is advantageous if a bandpass filter is arranged in the first measuring path at a position between the first light source and the first photodetector. The bandwidth depends on the optical components used and results from the intensity characteristic of the first light source, the transmission characteristic of the measuring chamber and the optionally existing beam splitter and the sensitivity characteristic of the first photodetector. Although devices are preferred that give a low bandwidth, it is also possible thanks to this development to use components that bring a larger bandwidth with it.

In order to facilitate the legally required operator controls, it is advantageous if the device is a transmission unit, for. B. a GSM module, for transmitting the determined and / or evaluated measured values to an external receiver. By transmitting the obtained measurement data to any location is an online remote monitoring of the device z. B. via mobile / GSM and saves the ongoing visual inspection on site. Any existing functional problems can be quickly identified and remedied by the operator or a service company. Of the external receiver is for example a mobile phone or a computer. In the case of a mobile phone, the measured data can be transmitted via SMS, for example.

The device may further comprise an operator console for inputting commands for the control and evaluation device, for example for programming the measurement sequence and its time sequence. The control panel may further comprise a display for displaying the commands or the measurement and identification data or a touchscreen.

Advantageously, the device for power supply to a replaceable power supply module, for example, commercially available dry batteries, on. Advantageously, the device for battery level control is further associated with an alarm device which triggers an alarm signal with little or a failure of the power supply. The alarm device may be part of the control and evaluation or a separate component. Thus, in the event of a power loss or a failure of the power supply module, as a result of which the functional reliability of the device is no longer guaranteed, an acoustic signal is activated, an indication is shown on the display or, by means of the transmission device, information is sent to the external receiver, e.g. B. in the form of an SMS to a mobile phone, are transmitted.

In addition, by means of a counter (counter), which counts the measuring cycles, the level of the cleaning fluid to be monitored, and in analogy to the battery level control, an alarm signal is transmitted as described above, when the level falls below a predetermined limit.

The device may also be associated with a temperature sensor (temperature sensor), which is preferably located in the vicinity of the measuring chamber and is in signal communication with the control and evaluation device. Temperature deviations that exceed a predefinable temperature range can also be transmitted as an alarm signal as described above.

In order to clean that section of the supply line which lies upstream of the at least one valve means for supplying the cleaning fluid, it is advantageous if the at least one valve means is arranged in the supply line and the device has a backwash valve which is located in the supply line at a position between the at least one valve means and the measuring chamber is arranged and from which a backwash line extends to the supply line, wherein the backwash line opens at a position upstream of the at least one valve means in the supply line. By this apparatus arrangement, it is possible to backwash the feed line of the measuring chamber with the cleaning fluid by reversing the flow direction of the cleaning fluid and thus counteract biofilm formation.

The terms "upstream" and "downstream" always refer to the flow direction of the aqueous liquid to be investigated (= water sample), which is conducted through the supply line into the measuring chamber and from there flows further into the discharge line.

In order to protect the device components from splash water, this is advantageously accommodated in a watertight housing, wherein the housing has inlet and outlet openings through which the supply and discharge lines extend.

• a) Spülen der Messkammer mit der wässrigen Flüssigkeit,
• b) Bestimmen der optischen Eigenschaften der wässrigen Flüssigkeit mittels des ersten optischen Sensors, und gegebenenfalls mittels des zweiten und/oder dritten optischen Sensors,
• c) Spülen der Messkammer mit zumindest einem Reinigungsfluid,
• d) Auswerten der mittels der optischen Sensoren erhaltenen Messwerte mittels der Steuer- und Auswerteeinrichtung, und
• e) Übermitteln der ausgewerteten Messwerte mittels einer Übertragungseinheit, insbesondere eines GSM-Moduls, an einen externen Empfänger.

Another object of the invention relates to a method for monitoring parameters of an aqueous liquid, in particular wastewater, using a device according to the appended claims and as described above, the method being characterized by the following steps:

• a) rinsing the measuring chamber with the aqueous liquid,
• b) determining the optical properties of the aqueous liquid by means of the first optical sensor, and optionally by means of the second and / or third optical sensor,
• c) rinsing the measuring chamber with at least one cleaning fluid,
• d) evaluating the measured values obtained by means of the optical sensors by means of the control and evaluation device, and
• e) transmitting the evaluated measured values by means of a transmission unit, in particular a GSM module, to an external receiver.

As already described above, it is favorable for reference measurements for calibration purposes or to compensate for temperature influences which are caused by the light sources, if a reference measurement is carried out prior to determining the optical properties of the aqueous liquid. Preferably, therefore, before step a) by means of the first and second optical sensors, and optionally carried out by means of the third optical sensor, at least one reference measurement by determining the optical properties of the cleaning fluid located in the measuring chamber. Thus, the cleaning fluid is used directly as a reference liquid and thereby enables a very simple and inexpensive apparatus design of the device according to the invention. To one of the currently applicable DIN standard no. 38404-3 / July 2005 To be able to carry out a corresponding zero measurement, it is expedient if optically pure water as described above is used as the cleaning fluid or as the reference fluid.

In order to avoid biofilm formation in the feed line, it is advantageous if, subsequent to step c), the supply line of the measuring chamber is backwashed by means of at least one cleaning fluid.

For the determination of specific water parameters (eg COD, BOD, DOC, coloration / humic substance load), it is advantageous if the measurements by means of the first optical sensor at a wavelength of 254 nm, by means of the second optical sensor at a wavelength of 550 nm and optionally by the third optical sensor at a wavelength of 436 nm.

In the following, the invention, together with further advantages, will be explained by way of non-limiting example, which is illustrated in the accompanying drawings. The drawings show:

1 a schematic block diagram of a device according to the invention,

2 an enlarged schematic sectional view of the measuring device of the 1 (in supervision),

3 a further enlarged schematic sectional view of the measuring device of the 1 (in side view),

4 to 7 the steps of a measurement procedure based on the representation of the essential device components of the 1 , and

8th a flow diagram of the measurement process including menu structure for the command input.

The 1 shows a schematic block diagram of a device according to the invention 100 for monitoring parameters of a water sample from a water management plant. Via a supply line 101 gets out of a water pipe 102 a water sample from a body of water 111 , z. As drinking water or wastewater, by means of an electrically operated diaphragm pump 103 sucked and in one, an optical measuring device 104 associated measuring chamber 121 (see detail view in 2 and 3 ) and from there via a derivative 105 back to the water pipe 102 promoted. The supply line 101 and the derivative 105 dive stationary into the water body 111 the water pipe 102 and are anchored there. The water pipe 102 is in particular a sewer, but can also be a drinking water line. The water sample passes over a sample inlet 101 in the supply line 101 , The sample inlet is in the body of water 111 preferably at a defined distance to the water surface 111 arranged. To keep this distance can be on the supply line 101 in accordance with a known type a floating body (float), not shown attached.

The optical measuring device 104 further comprises an optical measuring arrangement consisting of a plurality of optical sensors attached to the measuring chamber 121 are arranged (optical sensors 104a . 104b . 104c ; Detail view in 2 and 3 and description below). The diaphragm pump 103 is in the supply line 101 arranged. Furthermore, in the supply line 101 an intake valve 107 and a backwash valve 108 arranged. The intake valve 107 is located upstream of the diaphragm pump 103 ie in an upstream of the diaphragm pump 103 lying section of the supply line 101 , The backwash valve 108 is located in a section of the supply line 101 between the diaphragm pump 103 and the measuring device 104 , The device 100 also has a cleaning tank 109 for a cleaning liquid, which from the cleaning tank 109 via the intake valve 107 in the supply line 101 and from there into the measuring chamber 121 and the derivative 105 can be directed. The device 100 also has a backwash line 110 on which is from the backwash valve 108 in the supply line 101 extends and at a position upstream of the intake valve 107 in the supply line 101 empties.

The diaphragm pump 103 , the intake valve 107 , the backwash valve 108 and the optical measuring device 104 are via control and signal lines (a), (b), (c) and (d) with a control and evaluation 112 connected to the measurement process control and the measurement data evaluation, which in this example on a motherboard 115 is attached. The intake valve 107 and the backwash valve 108 For example, they can be realized as controlled 3/2-way solenoid valves or as controlled pneumatic valves and are of the control and evaluation device 112 driven. The optical sensors described in detail below 104a . 104b . 104c are from the control and evaluation device 112 independently activated. The control and evaluation device 112 is constructed in a manner known per se and typically has a microcontroller and electronic components.

The device 100 is also a transmission unit 114 assigned to the remote transmission of data, which in the in the 1 example shown is a GSM module. With the transmission unit 114 the determined and / or evaluated measured values are transmitted to an external receiver (not shown), which in the present example is a mobile telephone or a computer. For example, the measured data are transmitted by means of the transmission device 114 via SMS to a mobile phone.

On the motherboard 115 is a control panel 116 for entering commands for the control and evaluation device 112 arranged. Such commands include, for example, the programming of the measurement procedure and the measurement timing scheme. In the 1 has the control panel 116 a display 117 for displaying the commands, the measurement and characteristic data and / or the operating status as well as a keypad 118 for entering data (measurement procedure, measurement time scheme, data transmission time schedule, telephone number, PIN code of the SIM card, etc.). Instead of the display 117 and the keypad 118 can the control panel 116 have a touch screen.

The components of the device described above 100 are in a waterproof case 119 which z. B. made of PVC (polyvinyl chloride) is arranged. The waterproof case 119 has a sealed feed opening 119a and a sealed discharge opening 119b on, through which the supply line 101 or the derivative 105 , from the waterproof case 119 out into the water body 111 the water pipe 102 extend.

The device 100 For example, with the help of cable ties or the like can be fixed to existing components of the water management system.

For power supply is the device 100 a power supply module 113 , z. B. in the form of commercially available dry batteries assigned. To a power loss or failure of the power module 113 , in which a functional reliability of the measuring and cleaning process can no longer be guaranteed, can be seen the device 100 for battery level control further associated with an alarm device which triggers an alarm signal with little or a failure of the power supply. The alarm device can be part of the control and evaluation 112 or be a separate component. Malfunctions in the power supply can the operator of the water management system by means of an acoustic signal, an indicator on the display 117 or by the transmission of information by means of the transmission device 114 to the external receiver, z. B. in the form of an SMS to a mobile phone.

In addition, by means of a counter (counter), which counts the measuring cycles, the level of the cleaning liquid can be monitored, in analogy to the battery level control an alarm signal is transmitted as described above, when the level falls below a predetermined limit.

The device 100 can also be a temperature sensor 120 be associated with advantage in the vicinity of the measuring chamber 121 located and with the control and evaluation 112 is in signal connection. Temperature deviations that exceed a predefinable temperature range can also be transmitted as an alarm signal as described above.

Additional signal lines (e), (f), (g) and (1) between the transmission unit 114 , the power supply module 113 , the temperature sensor 120 and the motherboard 115 or between the control and evaluation device 112 and the control panel 116 are also in the 1 shown.

2 shows an enlarged schematic sectional view of the optical measuring device 104 from the 1 (in supervision). In addition, there is still the control and evaluation 112 shown. The optical measuring device 104 includes the already mentioned measuring chamber 121 which can be filled with the water sample to be measured or with cleaning fluid as described above. In the measuring chamber shown 121 it is a flow cell that is permeable to UV light and, for example, made of quartz glass or plastic is made. The optical measuring device 104 further comprises an optical measuring arrangement consisting of a plurality of optical sensors located outside the measuring chamber 121 are arranged at this.

The first optical sensor 104a has a controlled UV LED as the light source 122 with a peak intensity of 254 nm and a first photodiode 123 for measuring the light intensity passing through the in the measuring chamber 104 befindliches liquid (water sample, reference liquid) is transmitted on. In analogy to the first optical sensor 104a has the second optical sensor 104b as a light source a controlled LED 125 with a peak intensity of 550 nm (visible light in the green region) and a second photodiode 126 for measuring the light intensity passing through the in the measuring chamber 104 befindliches liquid (water sample, reference liquid) is transmitted on. An optional further education of the measuring device 104 further comprises a third optical sensor 104a , which as a light source is a controlled LED 128 with a peak intensity at 436 nm (visible light in the blue region) and a third photodiode 129 for measuring the light intensity passing through the in the measuring chamber 104 befindliches liquid (water sample, reference liquid) is transmitted. The measuring paths between the respective LEDs 122 . 125 . 128 and the photodiodes 123 . 126 and 129 run, are marked with arrows. The measuring chamber 121 and the optical components described above are in the example shown embedded in a plastic block (shown as a hatched rectangle), wherein the light channels through which the measuring paths extend are milled into the plastic block. The LEDs 122 . 125 . 128 and the photodiodes 123 . 126 . 129 . 131 are interchangeable from the outside. The LEDs 122 . 125 and 128 be from the control and evaluation unit 112 controlled in a conventional manner via signal connections (h), (i) and (j).

The 2 moreover, shows an advantageous development of the measuring device 104 , To fluctuations in the intensity of the UV LED 122 To compensate, their intensity is additionally using a reference photodiode 131 measured. For this purpose, in the measuring path between the UV-LED 122 and the measuring chamber 121 a beam splitter 133 arranged in the form of a semi-transparent mirror, which is about 30% of that of the UV LED 122 emitted UV light branches into a reference measuring path and the reference photodiode 131 supplies.

Alternatively, it is also possible for fluctuations in the intensity of the UV LED 122 to compensate for the threshold voltage of the first photodiode 123 recorded and during the measurement data evaluation by the control and evaluation unit 112 is taken into account. In this case, a beam splitter and a reference photodiode as described above can be dispensed with.

A further advantageous embodiment of the measuring device 104 who are also in 2 is shown, comprises one between the measuring chamber 121 and the first photodiode 123 arranged bandpass filter 137 , By means of the bandpass filter 137 errors due to excessive bandwidth can be excluded. The bandwidth depends on the optical components used and results from the intensity characteristic of the first light source, the transmission characteristic of the measuring chamber and the optionally existing beam splitter and the sensitivity characteristic of the first photoelectrode.

The first, second and third photodiodes 123 . 126 and 129 as well as the reference photodiode 131 detected light intensities are converted in a conventional manner into corresponding electrical signals, which subsequently in measuring amplifiers 124 . 127 . 130 and 132 , which are connected downstream of the photodiodes, amplified and via signal connections (k) of the control and evaluation device 112 be supplied for the further measurement data evaluation.

3 shows a further enlarged schematic sectional view of the measuring device 104 from the 1 (in side view), the section through the top in 2 described optical components of the first optical sensor 104a (UV-LED 122 , Beam splitter 133 , first photodiode 123 , Measuring amplifier 124 , Light channel 134 ) and the measuring chamber 121 leads.

From the 3 are also the connections 135 . 136 for the supply line 101 the liquid in the measuring chamber 121 and for the derivative 105 the liquid from the measuring chamber 121 recognizable.

4 to 7 illustrate the steps of a measurement procedure based on the representation of the essential device components of the 1 , wherein the direction of flow through the lines 101 . 105 . 110 and the measuring chamber 121 the device 100 flowing water sample (in the present example, it is wastewater) or cleaning fluid and the valve positions of the intake valve 107 and the backwash valve 108 represented by arrows.

In a first, in the 4 The step shown is the measuring chamber 121 Pre-rinsed with the cleaning fluid. This is done by means of the diaphragm pump 103 the cleaning fluid from the cleaning tank 109 at corresponding valve positions of the intake valve 107 and the backwash valve 108 over the supply line 101 into the measuring chamber 121 the measuring device 104 and from there via the derivative 105 in the water pipe 102 directed. Once the measuring chamber 121 is filled with the cleaning liquid to be calibrated by means of the first, second and third optical sensors 104a . 104b . 104c Reference measurements (zero measurements) were made at the wavelengths 254 nm, 550 nm and optionally at 436 nm. The reference measurement with the cleaning fluid can also compensate for temperature influences. The cleaning liquid thus serves at the same time as a reference liquid, which is preferably optically pure water. For example, the optically pure water one of the DIN standard no. 38404-3 / July 2005 according to quality DIN ISO 3639 exhibit.

In the following step of the measuring process, which is in the 5 is shown, after changing the valve position of the intake valve 107 the wastewater sample from the water body 111 the water pipe 102 into the measuring chamber 121 (see detail view in 2 and 3 ) of the measuring device 104 and from there via the derivative 105 back to the water pipe 102 directed. Once the measuring chamber 121 is filled with the water sample are, in analogy to the reference measurement described above by means of the first, second and third optical sensors 104a . 104b . 104c the optical properties of the water sample at the wavelengths 254 nm, 550 nm and optionally at 436 nm determined photometrically.

The measurement of the optical properties in cleaning fluid or in wastewater with the third sensor 104c at a wavelength of 436 nm to determine the DOC is optional. If the water sample to be examined is drinking or groundwater, the DOC can also be used to draw conclusions about the coloration / humic substance load.

As in 2 The reference intensity of the UV LED is described both in the reference measurement in cleaning fluid and in the measurement of the water sample (waste water) 122 of the first optical sensor in addition to the reference photodiode 131 measured to fluctuations in the intensity of the UV LED 122 to compensate.

The reference measurement in cleaning fluid and the measurement of the wastewater sample is usually carried out by cyclic scanning of the individual photodiodes. For example, a total of 256 cycles are performed and the measured values are averaged. The measuring time amounts to a total of about 1 second. The result is an integer value of 0-1000, which represents the light intensity.

The following measured values of the light intensity [I] are therefore determined by means of the first, second and third sensors 104a . 104 . 104c receive: 254 nm (UV) intensity for cleaning fluid: I _UvSpuMes 245 nm (UV) reference intensity for cleaning fluid: I _UvSpuRef 254 nm (UV) intensity in wastewater: I _UvabwMes 254 nm (UV) reference intensity for wastewater: I _UvAbwRef 550 nm (green) Intensity of cleaning fluid: I _GrSpu 550 nm (green) intensity in wastewater: I _GrAbw 436 nm (blue) Intensity of cleaning fluid: I _Bluespu 436 nm (blue) Intensity of wastewater: I _BlAbw

The term "reference intensity" refers to the light intensity associated with the reference photoelectrode 131 is measured.

The following calculations are based on the measured light intensities by means of the control and evaluation 112 carried out for wastewater: SSK ₂₅₄ [1 / m] = f / d ₁ · {[Log (I _UvSpuMes ) - Log (I _UvSpuRef )] + [Log (I _UvAbwRef ) - Log (I _UvAbwMes )] SKK ₅₅₀ [1 / m] = f / d ₂ · [Log (I _GrSpu ) - Log (I _GrAbw )] SSK ₄₃₆ [1 / m] = f / d ₂ * Log (I _BlSpu ) - Log (I _BlAbw )] (SSK ₂₅₄ = spectral scattering coefficient at 254 nm)
(SSK ₅₅₀ = spectral scattering coefficient at 550 nm)
(SSK ₄₃₆ = spectral scattering coefficient at 436 nm)
(f = the factor to obtain the spectral absorption coefficient in m ^-1 , typically f = 1000)
(d ₁ , d ₂ = optical path lengths of the measuring chamber 121 in mm. Depending on the construction of the measuring chamber 121 For example, d ₁ and d _{2 may be the} same or different. As in 2 shown is the optical path length d ₁ for the first sensor due to the better graphic representability 104a (Measurement of the SSK ₂₅₄ ) longer than the optical path length d ₂ for the second and the third optical sensor 104b . 104c (Measurement SSK ₅₅₀ or SSK ₄₃₆ ). In practice, it may, for. B. in heavily clouded water samples of advantage if the optical path length for the first sensor 104a is shorter.) SAK ₂₅₄ [1 / m] = SSK ₂₅₄ - SSK ₅₅₀ SAK ₄₃₆ [1 / m] = SSK ₄₃₆ - SSK ₅₅₀ (SAK ₂₅₄ = spectral absorption coefficient at 254 nm)
(SAK ₄₃₆ = spectral absorption coefficient at 436 nm) COD [mg / 1] = 2.39 · SAK _254-19 BOD ₅ [mg / 1] = 0.86 · SAK ₂₅₄ - 26.42 (COD = chemical oxygen demand)
(BOD ₅ = biological oxygen demand after 5 hours)

The device 100 is due to the sensors described above 104a . 104b . 104c designed for the photometric monitoring of wastewater parameters such as the COD or BOD5. However, it can also be used for photometric monitoring of drinking water parameters, with drinking water measuring at a wavelength of 550 nm can be omitted, since drinking water usually has no undissolved constituents. By appropriate programming of the measuring sequence, the corresponding sensors can be used depending on the water sample to be examined (eg waste water, drinking water) 104a . 104b . 104c independent from the control and evaluation 112 controlled / activated.

In the next step, in the 6 is shown, the measuring chamber 112 the measuring device 104 and the wires 101 . 105 rinsed with cleaning fluid and cleaned to remove impurities and counteract biofilm formation. The valve positions of the intake valve 107 and the backwash valve 108 correspond to those from the 4 ,

To that section of the supply line 101 , which is upstream of the intake valve 107 between the intake valve 107 and the body of water 111 is to clean, in a further step, in the 7 is shown, the cleaning fluid by appropriate valve position of the backwash valve 108 in the backwash line 110 and further into the supply line 101 directed. The section of the supply line 101 , which is upstream of the intake valve 107 ie essentially between intake valve 107 and water pipe 102 , is, therefore, by flushing with cleaning fluid in a flow direction opposite to the flow direction of the sample of water removed (see 5 ) cleaned.

Following the in 7 cleaning step shown, the measuring device is placed in the rest position (diaphragm pump 103 off, valves 107 . 108 de-energized). The measured data obtained are as described above by means of the control and evaluation device 112 evaluated and with the help of the transmission device 114 (GSM module) to an external receiver (SMS to mobile phone). For example, to transmit an SMS to a mobile phone, the phone number of the mobile phone and the PIN code of the SIM card of the transmission device 114 entered. In the SMS, the status of the measurement, SAK254 value, COD value, BOD value, SSK550 value, temperature and battery voltage are transmitted, for example, as follows:
Day: FR
Measurement Ok
VS: 0x
SAK: 26 <1 / m>
COD: 43 <mg / 1>
BOD: 0 <mg / 1>
SSK550: 0 <mg / 1>
Temp 21 <C>
VBat: 11.8 <V>

• 1) 8 Sekunden Vorspülen der Messkammer 121 mit Reinigungsflüssigkeit (optisch reines Wasser).
• 2) 20 Sekunden warten und Referenzmessung in Reinigungsflüssigkeit zur Kalibrierung.
• 3) 30 Sekunden lang Ansaugen von Abwasser durch die Messkammer 121.
• 4) 20 Sekunden lang warten und Messung im Abwasser durchführen.
• 5) 8 Sekunden Spülen der Messkammer 121 mit Reinigungsflüssigkeit zur Reinigung.
• 6) 8 Sekunden Spülen des stromauf des Ansaugventils 107 liegenden Abschnitts der Zuleitung 101 mit Reinigungsflüssigkeit durch Rückleiten der Reinigungsflüssigkeit über das Rückspülventil 108 und die Rückspülleitung 110 in die Zuleitung 101.
• 7) Ruhestellung (Pumpe 103 aus, Ventile 107, 108 stromlos) und Auswerten und Schicken der Messdaten per SMS an ein Mobiltelefon.

The timing of the in the 4 to 7 For example, the described measurement sequence may look like this:

• 1) Pre-rinse the measuring chamber for 8 seconds 121 with cleaning fluid (optically pure water).
• 2) Wait 20 seconds and reference measurement in cleaning fluid for calibration.
• 3) Aspirate wastewater through the measuring chamber for 30 seconds 121 ,
• 4) Wait 20 seconds and measure in the waste water.
• 5) Rinse the measuring chamber for 8 seconds 121 with cleaning fluid for cleaning.
• 6) Rinse the upstream of the suction valve for 8 seconds 107 lying section of the supply line 101 with cleaning fluid by returning the cleaning fluid through the backwash valve 108 and the backwash line 110 in the supply line 101 ,
• 7) Rest position (pump 103 off, valves 107 . 108 de-energized) and evaluating and sending the measurement data via SMS to a mobile phone.

8th shows a flowchart of the in the 4 to 7 described measuring sequence including menu structure for the command input and with reference to the in 1 illustrated keypad 118 ,

The in the 4 to 8th The measuring procedure described can be programmed through a programmed time schedule by entering commands in the control panel 116 is programmable, to be activated at desired times of the day. Usually the measurements are carried out at regular intervals at certain times and / or on certain days. Outside the time schedule, an immediate measurement can be performed.

Between the individual measurements is the device 100 preferably in power-saving mode. This will be the power supply of the pump 103 , the valves 107 . 108 , the indicator on the display 117 and the peripheral components (GSM modem, measuring amplifier etc.) switched off.

The figures shown herein are for understanding the measuring principle and are not intended to be exact construction drawings.

The embodiment described above, including its advantageous developments, is only one among many and not to be considered as limiting.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009028254 A1 [0006]
• GB 2256043 A [0007]
• EP 0724718 [0008]
• DE 10228929 A1 [0009]
• DE 102008028058 A1 [0010]
• DE 102004063720 [0011]

Cited non-patent literature

• EU Water Framework Directive 2000/60 / EC [0015]
• DIN 38404-3; current status: July 2005 [0021]
• DIN standard no. 38404-3 / July 2005 [0025]
• DIN ISO 3696 [0025]
• DIN standard no. 38404-3 / July 2005 [0039]
• DIN standard no. 38404-3 / July 2005 [0068]
• DIN ISO 3639 [0068]

Claims (20)

Contraption ( 100 ) for monitoring parameters of an aqueous liquid, in particular wastewater, comprising: a measuring chamber ( 121 ) with a supply line ( 101 ) for the liquid to be tested and a derivative ( 105 ), an optical measuring arrangement with at least one optical sensor ( 104a . 104b ) for measuring at least one optical property of the liquid, and a control and evaluation device ( 112 ), characterized in that the optical measuring arrangement comprises a first optical sensor ( 104a ) and a second optical sensor ( 104b ), wherein the first optical sensor ( 104a ) a first light source ( 122 ), which emits UV light, a first photodetector ( 124 ) and one between the first light source ( 122 ) and the first photodetector ( 124 ) has a first measuring path, wherein the second optical sensor ( 104b ) a second light source ( 125 ) emitting visible light, a second photodetector ( 126 ) and one between the second light source ( 125 ) and the second photodetector ( 126 ) has a second measuring path, wherein the first and the second measuring path through the measuring chamber ( 121 ) and the liquid therein, the supply line ( 101 ) or the derivative ( 105 ) at least one valve means ( 107 ), through which at least one cleaning fluid into the measuring chamber ( 121 ), the device ( 100 ) at least one pumping means ( 103 ) for passing the liquid or the at least one cleaning fluid through the measuring chamber ( 121 ), and the control and evaluation device ( 112 ) for the programmable control of at least the pump and valve means ( 103 . 107 . 108 ) and for evaluating the measured values determined by means of the optical measuring arrangement. Apparatus according to claim 1, characterized in that the first light source ( 122 ) UV light with a wavelength of 254 nm and the second light source ( 125 ) emitted visible light with a wavelength of 550 nm. Device according to Claim 1 or 2, characterized in that the optical measuring arrangement has a third optical sensor ( 104c ) having a third light source ( 128 ) emitting visible light, a third photodetector ( 129 ) and one between the third light source ( 128 ) and the third photodetector ( 129 ) has a third measuring path, wherein the third measuring path through the measuring chamber ( 121 ) and the liquid therein. Device according to claim 2 and 3, characterized in that the third light source ( 128 ) emitted visible light with a wavelength of 436 nm. Device according to one of claims 1 to 4, characterized in that the first, the second and the third light source ( 122 . 125 . 128 ) have an LED (Light Emitting Diode). Device according to one of claims 1 to 5, characterized in that the control and evaluation device ( 112 ) is adapted, due to the filled with cleaning fluid measuring chamber ( 121 ) To carry out reference measurements. Device according to one of claims 1 to 6, characterized in that between the first light source ( 122 ) and the measuring chamber ( 121 ) a beam splitter ( 133 ) is arranged, which a portion of the of the first light source ( 122 ) emitted UV light in a reference measuring path and a reference photodetector ( 131 ) feeds. Device according to one of claims 1 to 6, characterized in that the control and evaluation unit ( 112 ) is adapted to set the threshold voltage of the first photodetector ( 123 ) and to take into account in the evaluation of the measured values. Device according to one of claims 1 to 8, characterized in that in the first measuring path at a position between the first light source ( 122 ) and the first photodetector ( 123 ) a bandpass filter ( 137 ) is arranged. Device according to one of claims 1 to 9, characterized by a transmission unit ( 114 ), in particular a GSM module, for transmitting the determined and / or evaluated measured values to an external receiver. Device according to one of claims 1 to 10, characterized by an operating console ( 116 ) for inputting commands for the control and evaluation device ( 112 ). Device according to one of claims 1 to 11, characterized in that the device ( 100 ) for power supply a replaceable power supply module ( 113 ) having. Device according to claim 12, characterized in that the device ( 100 ) is associated with an alarm device which triggers an alarm signal in case of low or a failure of the power supply. Device according to one of claims 1 to 13, characterized in that the at least one valve means ( 107 ) in the supply line ( 101 ) and wherein in the supply line ( 101 ) at a position between the at least one valve means ( 107 ) and the measuring chamber ( 121 ) a backwash valve ( 108 ), wherein the backwash valve is a backwash line ( 110 ) to the supply line ( 101 ) and wherein the backwash line ( 110 ) at a position upstream of the at least one valve means ( 107 ) into the supply line ( 101 ) opens. Device according to one of claims 1 to 14, characterized by a watertight housing ( 119 ) in which the device ( 100 ), wherein the housing ( 119 ) Inlet and outlet openings ( 119a . 119b ), through which the supply and discharge lines ( 101 . 105 ). Method for monitoring parameters of an aqueous liquid, in particular wastewater, using a device ( 100 ) according to one of claims 1 to 15, characterized by the following steps: a) rinsing of the measuring chamber ( 121 ) with the aqueous liquid, b) determining the optical properties of the aqueous liquid by means of the first optical sensor ( 104a . 104b ), and optionally by means of the second and / or third optical sensor ( 104c ), c) rinsing the measuring chamber ( 121 ) with at least one cleaning fluid, d) evaluation by means of the optical sensors ( 104a . 104b . 104c ) by means of the control and evaluation device ( 112 ), and e) transmitting the evaluated measured values by means of a transmission unit ( 114 ), in particular a GSM module, to an external receiver. A method according to claim 16, characterized in that before step a) by means of the first and second optical sensors ( 104a . 104b ), and optionally by means of the third optical sensor ( 104c ), at least one reference measurement by determining the optical properties of the in the measuring chamber ( 121 ) is carried out cleaning fluids. A method according to claim 16 or 17, characterized in that subsequent to step c) the supply line ( 101 ) of the measuring chamber ( 121 ) is backwashed by means of at least one cleaning fluid. Method according to one of claims 16 to 19, characterized in that in step d) the threshold voltage of the first photodetector ( 123 ) is taken into account in the evaluation of the measured values. Method according to one of claims 16 to 19, characterized in that the measurements by means of the first optical sensor ( 104a ) at a wavelength of 254 nm, by means of the second optical sensor ( 104b ) at a wavelength of 550 nm and optionally by means of the third optical sensor ( 104c ) at a wavelength of 436 nm.

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