SELUTEC

SELUTEC GmbH
Environmental technology - Respirometer

The biochemical oxygen demand (BOD) is one of the important parameters for classifying the pollution level of waste waters because it corresponds largely to the biochemical oxidation of organic substances in sewage purification plants.

In waters and water treatment facilities, organic substances are reduced by oxidation by means of the metabolism of bacteria. The amount of oxygen which is necessary for this biochemical oxidation of organic substances is defined as "BOD". As the solubility of oxygen in water is relatively small, the same amount of oxygen must be added to the water for biochemical oxidation as the amount which is consumed by the micro-organisms. If this were not the case, the oxygen content of the water would rapidly be reduced to zero, the organic matter would be decomposed by anaerobic micro-organisms in a process of putrefaction, and the whole process would be considerably slower.


Sapromat
Respirometer

Respirometer BSBdigi O2 / BSBdigi CO2
Specialties of the system

Thank to its modular design, the BSB digi system can be extended to up to more than 100 measuring points. This allows individual adaption of the system to the requirements of the use.

Advantages

  • The compact construction requires little surface space
  • By a continuous balance of consumed oxygen, a very high oxygen depletion can be detected without sample dilution
  • Tempering is carried out in air, thus no corrosion and no creeping current
  • The oxygen consumption can be registered for any random time intervals, thus an affirmative consumption curve is always possible thank to its modular design, the BSBdigi system can be extended to up to more than 100 measuring points. This allows individual adaption of the system to the requirements of the user
  • high pressure constancy
  • no stress for bio-organism

Standard - stirrer system with 6 measuring places

Standard - stirrer system with 6 measuring places







BSBDigi O2
BSBdigi CO2

The amount of CO2 microbialy generated is estimated via its absorption in a KOH solution with measuring the change in conductivity. Determining O2-consumption in connection with CO2-production during the biological degradation process allows a secure and unambiguous judgment of biodegradation.

Thus an evaluation of the extent of ultimate aerobic biodegradation, defined as the break-down of an organic chemical compound by microorganisms in the presence of oxygen into carbon dioxide, water, mineral salts (mineralization) and new biomass can be approached. In addition it improves the possibilities of a desirable C-balancing.

 BSBDigi CO2

Guidelines
Testing directions Test
ISO / DIS 14851 Plastics - Evaluation of the ultimate aerobic biodegradability in an aqueous medium - Method by determining the oxygen demand in a closed respirometer
ISO / DIS 14852 Plastics - Evaluation of the ultimate aerobic biodegradability in an aqueous medium - Method by analysis of released carbon dioxide
ISO-Proposal (1998) Plastics - Determination of the ultimate aerobic biodegradability in soil by measuring the oxygen demand in a closed respirometer or the amount of carbon dioxide released
OECD 301 B CO2 Evolution test
OECD 301 C Modified MITI test
OECD 301 F Unterscheidet sich von 301 C im Einsatz der Inokula

Download: Particularize description, PDF

Co-operation partner:

University of Stuttgart, Institute of Sanitary Engineering, Water Quality and Solid Waste Management, Department Biology, Bandtäle 1, 70569 Stuttgart, Germany