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World’s Leading supplier in Precision Dissolved Oxygen Measurement and Respirometry

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 To see how easy the Strathtox is to use click here

Precision respirometer for rapidly measuring actual Activated Sludge bacterial performance.

  • Advanced 6-cell precision OUR measurement system
  • Easy and rapid test procedures
  • User friendly software providing a real-time display of bacterial respiration
  • Automatic Report generation and calculation of EC10,20,50 values for carbonaceous and nitrifying bacteria
  • Efficient procedures and advanced equipment design prodcuces results in as little as 10 minutes
  • Tests provided are: Carbonaceous and Nitrifying Sludge Health, Critical Oxygen Point Analysis, Respiration Inhibition, Nitrification Inhibition, BOD(ST),  Respirometry,Process Optimisation (Calculates Critical Dissolved Oxygen Concentrations).
  • Applications in:
    - Toxicity Management
    - Nitrification Management
    - Aeration Efficiency
    - Nutrient Control
    - Sludge Health
    - System Trouble-shooting
    - Short-term BOD
    - Plant capacity
    - Respiration tests

Strathtox is an integrated desktop respirometer comprising the following sub-systems:

Temperature controlled Circulating Waterbath This is used to maintain the activated sludge at constant temperature during a respirometry run. A six position magnetic stirrer is located beneath the bath. The six 20ml respirometer cells are located in a rack, for easy removal at the end of a run.

Activated Sludge Temperature Controlled Containment A flask provides aeration and containment of approximately 600ml of AS that can also be split for Nitrification testing.

Oxygen Electrodes These high precision electrodes are housed in electrode holders for easy insertion into the respirometer cells. They require little maintenance, other than occasional membrane changes. Great care must be taken when maintaining these please see the following – electrode care.

Oxygen Interface, the six oxygen electrodes are connected to this unit, which transmits the digital signals to the computer software.


The easy-to-use Windows based software comprises 5 different tests. Each test program has a similar basic structure compromising four stages: Setup; Recording; Analysis; Report. To illustrate this, sample screens from a Respiration Inhibition Test are shown below.

Setup – This is the first screen and is used to input the data about the test. This information is transferred to the final Report.

Recording – Clicking a ‘Start’ button on the toolbar of the Setup screen, commences the recording. Six traces scroll across the screen, providing a visual check on the rate and linearity of the decline in the oxygen content of the cells as respiration proceeds. At the end of the run, a file is created to save the data.

Report - The report window provides information on the respiration rates, inhibition or (Toxicity) values, an inhibition v concentration graph and a respiration v concentration plot, together with a full audit trail. The report is in the form of a locked spreadsheet, so data cannot be altered. The data can however, be exported to Excel, or a database for further processing, if required. The report and associated Analysis screen can be printed or saved to an archive folder.

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Strathkelvin Instruments Limited,

Rowantree Avenue,

North Lanarkshire, ML1 5RX,


01698 730400
Fax: 01698 730401
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