SN8 On-line Respirometer

  • sn8
  • SN8_Font de la Pedra_1_1
  • comunicaciones
  • Gráficas biológico 1
  • OUR-ph 18032020_1
  • OURs 18032020_1
  • OD Galvánico
  • ORP_2
  • pH_1
  • ORP_1
  • pH_4
Technical Data
ficha-tecnica_SN8_english.pdf (1.66MB)
Technical Data
ficha-tecnica_SN8_english.pdf (1.66MB)
Flyer SN8 English
flyer_SN8_respirometro 2018_english.pdf (169.08KB)
Flyer SN8 English
flyer_SN8_respirometro 2018_english.pdf (169.08KB)

The SN8 is an online respirometer which is designed to interact with the process and serve as a tool for better control and optimization. For this purpose, the SN8 has sensors for oxygen, pH and Redox and optionally for ammonium. It can also be configured to control either one or two biological reactors with the same unit.


Using the SN-8 respirometer, the following tests are carried out that provide the following parameters automatically:

  • OUR TEST (Global Respirometry): OUR, SOUR, pH, ORP, Temperature
  • AUR TEST (Nitrification Rate): Rn, AUR, pH, ORP, Temperature
  • TOX TEST (Toxicity): % Inhibition
  • COD TEST: Biodegradable COD


  • Primary evaluation of the sludge
  • Detection of waste discharges
  • Automatic control of aeration based on respirometry
  1. Energy optimization: both in the nitrification and in industrial plants with or without nitrification.
  2. Optimization of SBRs.

  • Automatic control of nutrient dosage, based on respirometry.

Respirometry in the active sludges process

  • Respirometry is a technique that allows us to assess, control and protect the active sludge process by providing information about the state or the activity of the biomass. This enables us to anticipate most of the problems that may affect the process, so guaranteeing, right from the outset, that the correct decisions are taken to counter these problems.
  • Respirometry is also a necessary tool for optimizing the active sludge process and the level of toxicity of the wastewater for the microorganisms. It also determines the essential parameters for modeling this process.


  • Can be configured from a basic respirometer.
  • More than one reactor can be controlled with the same unit.
  • Unaffected by the level of the pool.
  • Low maintenance sensors.
  • Reproduction of the process in real conditions.
  • Can be installed at different points of the process.
  • Configured with MODBUS TCP communication, 4-20 or 0-10V outputs, to enable it to be integrated into the plant’s control system. Remote control, database and email alerts.


  • Touch-screen user interface
  • Software for the automatic calculation of OUR/SOUR, Rsn/AUR, etc.
  • Simple data transfer for PC.
  • Data history.
  • Portable cabinet measuring 400x500mm.


  • Wifi, Ethernet connection
  • Modbus communication
  • Data registry
  • Trend graphics.
  • Data export.
  • Software for computers.
  • APP for mobile devices.



  • Range: 0 - 35mg/l.
  • Max. Temp.: 50ºC.
  • 1 or 2 calibration points (air saturation and 0ppm).
  • Response time 0.06 mg/ 1 sec.


  • Range: 0-14 (Na+ error at > 12.3 pH)
  • Temp. range: 1-99ºC (212ºF).
  • Response time: 95% in 1 second.
  • Isopotential point: pH 7.00 (0 mV)


  • Range: -200ºC to 850ºC.
  • Type of sensor: Class A platinum, RTD.
  • Accuracy: +/- (0.15 + (0.002*t)).
  • Response time: 90% in 13s.


  • Range: +/- 2000mV.
  • Temperature: 80ºC (176ºF).
  • Response time: 95% in 1 second.
  • Dimensions: 12mm x 150mm (1/2” x 6”).