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Analysers Online

BOD Analyser BioMonitor

  • Measurement range: 1-200.000 mg/L BOD, ASR: 0 - 5 mg/L/min
  • Measurement method: Continuous 2 stream respiration measurement
  • Response time: 3-4 min. (customizable)
  • High degradation
  • Sludge activity
  • Using the plant's own biomass
  • No memory effects




  • Environmental protection
  • BOD monitoring
  • WWTP control
  • Detailed application overview
  • FlowSampler
  • Sludge recycling system

  • IP54 (Standard)

Online BOD for optimal waste water treatment plant control.

LAR's BioMonitor is the ultimate online BOD Analyser for the determination of biological oxygen demand (BOD) & respiration.

The miniature waste water treatment plant. Use of the own activated sludge.

Similar to the functional principle of a biological treatment plant, the waste water to be tested is mixed with activated sludge and air and continuously passed through the measurement cascade. Upon exiting the reactor cascade, the residual oxygen of the air is carried out and is measured with an oxygen sensor, wherein the volume flows of waste water, activated sludge and air are well defined or controlled. Important in this process is that the system's activated sludge is used to actually simulate the biology of the plant. Thus, the measurement results are of special relevance to the circumstances of the treatment plant and are always directly proportionate to their specific characteristics.

The total BOD.

In contrast to the standard BOD5 method the BioMonitor measures the total BOD. In the BOD5 measurement nitrification inhibitors are added to the sample, which suppress the degradation of nitrogen compounds. This results in the determination of the degradation of carbon compounds (carbonaceous-BOD) only. The nitrification part is not considered in BOD5 measurements.

As a waste water treatment plant can be reliably controlled and monitored only by the determination of total BOD, the BOD5 is insufficient for this purpose.

Alternatively to the BOD5 measurement LAR AG provides an online respirometer, which operates like a miniature waste water treatment plant: The BioMonitor.

The BOD analyser degrades nitrogen and carbon compounds in special waste water cascades, so that the meaningful total BOD can be determined within 4 minutes.

The BioMonitor. Ultra quick measurements and maintenance.

The measurement of the BOD takes place in less than 4 minutes and therefore it is faster than the BOD5 measurement, which requires 5 days. This speed guarantees that very short peaks can be determined very well during a daily cycle.

Measurement Principle Explained

Screenshot 2020 07 31 at 10.27.16

  1. Measurement results are displayed on the Analyser screen (human interface).
  2. The aerated mixture of activated sludge and sample is pumped through the four reactors.  The O2 sensor determines the oxygen consumed during decomposition. 
  3. The activated sludge is aerated and its respiration is determined (ASR).