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WTW BOD Information
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Biochemical Oxygen Demand
In “dilution BOD” the oxygen content of a sample is measured with a dissolved oxygen sensor before and after an incubation period of 5 days.
The difference between the measurements is the BOD 5value; this is the official EPA method.
In “BOD self-checks” with the respirometer, the reduction in oxygen causes a definite pressure difference that can be measured by a pressure sensor. This practical method is very easy to perform.
Both methods are very different, but the measurements correlate directly to the discharge seen at municipal wastewater treatment facilities.
Both methods require the samples to be kept at 20 °C (68 °F) for 5 days. WTW offers a wide range of temperature controlled incubators.
Depletion/Respiration
As environmental consciousness increases, microbiological degradability tests have become increasingly important, from soil surveys from waste sites to environmental impact surveys to characterize new chemical substances.
The necessary respiration measurements for anaerobic or aerobic degradation can be easily performed using the high performance OxiTop®-C systems. WTW offers a wide range of application specific packages complete with the appropriate sample vessels.
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OxiTop®/OxiTop® Control: Composition of complete packages
Catalog extract download PDF file
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- Compact
- Precise
- Uniform temperature distribution
OxiTop® Box with hinged, non-corrosive, clear-view cover accommodates a maximum of either 12 OxiTop® simultaneous measurements or 20 Karlsruhe bottles.
The chamber is equipped with a connection for an IS 6 or IS 12 stirrer.
A special compartment is provided for 6 methylene blue samples.
A cross ventilation fan ensures uniform temperature distribution and automatic defrosting system with condensate evaporation, plus the compressor is CFC-free.
| Temperature control
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20 °C ±0.5 °C / 68 °F (tolerance 67.1 - 68.9 °F)
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| Ambient temperature
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Storage: 25 °C ... +50 °C (-13 … +122 °F)
Operation: +10 °C ... +32 °C (+50 … 89.6 °F)
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| Power consumption
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200 W
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| Dimensions (H x W x D)
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375 x 425 x 600 mm 14.76 x 16.73 x 23.62 in
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According to DIN EN 1899-1 and DIN EN 1899-2; official EPA method
- Simple sample management
- Automatic BOD calculation
- EPA approved
This laboratory dissolved oxygen meter has been developed especially for BODn measurements, which are determined by regulation EN 1899-1 and Chapter5210.B of the “Standard Methods for the Examination of Water and Wastewater”.
You can store up to 7 of your own routines for frequently occurring dilution ratios.
A maximum of 30 measuring samples, each with 18 dilutions, allows the management of up to 540 diluted samples.
The inoLab® BSB/BOD 740 can also be used as a conventional high-end DO meter (for technical data such as inoLab® Oxi 740, refer to page 45).
Additional memory and editing options are available when operated using the MultiLab® pilot. The entire measurement and sample management can easily be handled via PC.
In combination with StirrOx® G with its automatic start/stop function the inoLab® BSB/BOD 740 is the ideal measuring system for routine DO measurement in the BOD5 determination according to DIN EN 1899-1 and DIN EN 1899-2.
Special features:
- BOD/depletion
- Determination of the biochemical oxygen demand according to DIN EN 1899-1
- Determination of oxygen depletion according to DIN 38 414 P6
- Up to 5 samples for dilution water
- Up to 30 measuring samples
- Up to 18 dilutions per measuring sample
- Up to 7 routines can be stored
- Adjustable incubation time, from 5 to 30 days
Additional features when using the MultiLab® pilot:
- Management of an arbitrary number of samples
- Max. of 32 dilutions per measuring sample
- Max. of 32 dilution waters (blank solutions)
- Adjustable incubation period, 1 to 32 days
- Allocation of names for dilution waters, samples, diluted samples and routines (max. of 255 characters per name)
- Warning indication for BOD values that are too high or too low
- Calculations by mouse click
- Automatic protocols
| Conc.
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0.00 ... 20.00 mg/l
0.0 ... 90.0 mg/l**
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| Saturation
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0.0 ... 200.0%
0 ... 600%**
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| Part. pressure
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0.0 ... 200.0 mbar
0 ... 1250 mbar
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| Temperature
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-5.0 ... +50.0 °C
(23 … 122 °F)
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** = depends on DO sensor and medium
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- EPA approved method
- Accurate
- Battery and AC power operation
Laboratory dissolved oxygen meter ProfiLine Oxi 1970i with self-stirring DO sensor StirrOx® G.
| Conc.
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0.00 … 19.99 mg/l (19.9 mg/l*)
0.0 … 90.0 mg/l (90 mg/l*)
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| Saturation
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0.0 … 199.9% (199%*)
0 … 600%
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* depends on DO sensor and medium
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Respiration/Biogas Determination with OxiTop® and OxiTop® Control
- High-precision
- 5-day automatic storage of measured values
- Portable
- Extendable
Complete packages for 6 or 12 simultaneous measurements
Measurement using OxiTop® is based on pressure measurement in a closed system: microorganisms in the sample consume the oxygen and form CO2; the CO2 is absorbed by NaOH, creating a vacuum that can be measured as a mg/l BOD value.
The sample volume used regulates the amount of oxygen available for a complete BOD.
Measurement ranges of up to 4,000 mg/l can be measured using different volumes.
The OxiTop® heads (green and yellow for inflow/outflow differentiation) have an AutoTemp function: if the sample temperature is too cold, the start of measurement is automatically delayed by at least 1 hour until a constant temperature has been reached.
Apart from the automatic storage of 5 measured values (1 value per day), further measured values can be read at all times during or after the period of 5 days, which permits the tracking of check values or measurements over longer periods.
Measurement range
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0 ... 40 digit
corresponding to
0 ... 40 / 80 / 200 / 400 / 800 / 2000 / 4000 mg/l BOD
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- Controller-driven
- Simultaneous measurement of up to 100 samples
- Statistical evaluation
- Automatic sample ID
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Complete package for 6 or 12 simultaneous measurements OxiTop® Control system uses software-controlled functions and infrared interface to communicate with the powerful OC 100 controller.
This connection enables the simultaneous, group start, management, storage and tracking of 100 measuring heads, and tracks results on a large graphic display.
Data can be transferred to the PC for evaluation and documentation via the AK-540/B cable (order no. 902 842) and the communication program Achat OC (order no. 208 990).
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- Simultaneous sample management with option of grouping up to 100 OxiTop®-C measuring heads.
- Data call-up of one parallel sample with statistical evaluation and as individual data.
- Automatic calculation and graphical display of BOD value.
- Data transfer even through glass doors.
- Protocol and documentation of data via Achat OC communication program in combination with a PC
- GLP and AQS with inspection intervals for calibration with the OxiTop® PM calibration tablets
| Data sets per measurement
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180 … 360 (depending on duration)
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| Measurement period
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0.5 h … 99 days
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- The OxiTop®-C measuring heads have an AutoTemp function; if the sample temperature is too cold, the start of measurement is automatically delayed, by up to 4 hours, until a constant temperature can be reached. This mode can be deactivated for BOD standard.
- The measuring heads can store up to 360 data sets. Data are automatically stored in the corresponding interval according to the interval period set (0.5 h to 99 days).
- The built-in pressure sensor can register differences in pressure ranging from 500 to 1,350 hPa.
Instead of the usual display and keys, the OxiTop®-C measuring head has an infrared interface with which it communicates with Controller OC 100 or OC 110.
By pointing the controller at an OxiTop®-C measuring head the sample can be identified and the measurement is started. Data can be called up or deleted and sampling progress can be displayed.
Each sample is automatically assigned a unique ID number; eliminating manual sample identification even for multiple samples.
In addition, statistical evaluations can be easily performed for multiple samples.
| Measuring principle
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Manometric with pressure sensor
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| Measurement of
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BODn
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| Pressure range
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500 - 1350 hPa
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| Accuracy
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±1% of value ±1 hPa
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| Resolution
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1 hPa (corresponds to 0.7% of BODn measuring range)
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- Individual measuring heads OxiTop®/OxiTop®-C
- A set of two OxiTop® heads (yellow and green).
- Upgrade sets for an additional 6 positions with 6 heads each and flasks, sleeves and stirring bars, as well as the stirring platform.
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To meet growth demands and accommodate additional applications, OxiTop® and OxiTop®-C systems are flexible and expandable.
Available as individual items in different combinations.
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Stirrers IS 6 and IS 12 have been specially developed for BOD measurement with the OxiTop® system. Software-controlled speed regulation prevents the magnetic stirrer bar from getting caught or wobbling. The speed is selected so that an optimal gas exchange with the sample takes place. The stirrer is maintenance-free and non-wearing as it contains no moving parts.
The IS 6-Var model has been specially developed for use with large measuring vessels and has space for 6 measuring vessels. Its outer dimensions are identical to those of the IS 12.
| Model
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IS 6
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IS 12
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IS 6-Var
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| No. of stirring positions
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6
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12
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6
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| Stirrer speed
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Program-controlled
180 ... 450 min-1
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Program-controlled
180 ... 450 min-1
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Program-controlled
180 ... 450 min-1
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| Ambient temperature
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Storage:-25 °C ... +65 °C
(-13 °F … 149 °F)
Operation: +5 °C ... +40 °C
(41 °F … 104 °F)
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Storage:-25 °C ... +65 °C
(-13 °F … 149 °F)
Operation: +5 °C ... +40 °C
(41 °F … 104 °F)
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Storage:-25 °C ... +65 °C
(-13 °F … 149 °F)
Operation: +5 °C ... +40 °C
(41 °F … 104 °F)
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| Dimensions (H x W x D)
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67 x 265 x 181 mm
(2.64 x 10.43 x 7.13 in)
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67 x 266 x 350 mm
(2.64 x 10.47 x 13.78 in)
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70 x 350 x 266 mm
(2.76 x 13.78 x 10.47 in)
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| Power supply
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Universal power supply 100-240V/50/60Hz
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Universal power supply 100-240V/50/60Hz
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Universal power supply 100-240V/50/60Hz
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For safe storage of OxiTop® measuring systems and OxiTop®-C measuring heads, for 6 measuring heads each.
For identification of BOD bottles for OxiTop® instruments.
In addition to the standard 164 ml and 432 ml overflow measuring flasks, 22.7 ml, 43.5 ml, 97 ml, 250 ml, 365 ml are also available.
Two testing aids are available for monitoring measurement and checking system leakage, which can be called up during a corresponding time interval using the AQA function in the controller.
These calibration tablets simulate a complete BOD and perform quantitative monitoring of measurement (approx. 308 mg/l, batch-dependent) as well as checks for leakage over the entire period.
This testing aid performs a “quick” check for under-pressure and leakage. The OxiTop® contains the pressure table required for the individual place of installation. OxiTop®-C automatically includes these values.
- A 325/K (plastic protective cap)
- A 325/S (stainless steel protective cap)
Armor to hold one ConOx, CellOx® 325 or TetraCon® 325. Available either with plastic protective cap (A 325/K) or stainless steel protective cap (A 325/S).
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Laboratory method for determining the microbial soil respiration according to DIN ISO 16072.
- Simple and precise
- Cost-efficient
- Optimum measuring vessels for subsequent quantitative determination of CO2
Soil respiration measurements are used for forecasting, surveying and checking remediation work, for biodegradability measurements of substances (pesticides, fungicides, fertilizers, etc.) and for carrying out toxicity tests. Thanks to specially designed, test-proven vessels, these measurements are made accurate and simple with the OxiTop® Control System. A cost effective alternative compared to conventional methods. Soil respiration measurements can be carried out in 2 different vessel types. For actively respiring soils with strong CO2 development, the MG 1.0 measuring vessel is recommended: its large opening (approx. 100 mm / 3.9 in dia.) easily fits large-volume CO2 absorber vessels for later quantitative CO2 determination.
Laboratory procedures for determination of biodegradability according to DIN EN 29 408 / ISO 9408 / OECD 301 F
The determination of the biodegradability should be checked before new chemicals are used for the first time, not only for environmental reasons but to minimize disposal charges. The sample and a blank are stirred at a constant temperature for 28 days in closed bottles. The CO2 produced is removed by means of an absorber, the resulting negative pressure is a measure of the biodegradability. The OxiTop®-C continuous value recording guarantees proper documentation. The measuring bottles and adapters can be autoclaved at 121 °C (249.8 °F).
Determination of anaerobic degradation processes: biogas determination
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Anaerobic degradation processes take place in the absence of oxygen.
A septum sealed bottle nozzle fills the head space above the sample with inert gas.
When anaerobic degradation has taken place, the dissolved CO2 can be driven off and then removed from the head space by means of a CO2 absorber.
The resulting pressure difference is proportional to the CO2 concentration; the remaining overpressure is proportional to the methane concentration.
The degradation process can be conveniently observed in the “pressure” operating mode.
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Microbiological growth and stress investigations: determination of the respiration rate (aerobic/anaerobic measurements)
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