Biochemical Oxygen demand (BOD) is an important parameter in water resource management to measure the quality of water and treatment results in wastewater treatment facilities.
In routine applications BOD determination is used to check the waste water in the inflow and discharge effluent of waste water treatment plants. Depending on the measurement site and the type of discharge BOD values can vary from a few mg/l to several thousand mg/l.
Several methods are available for the measurement of BOD:
- 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 BOD5 value; this is the official EPA method
- In BOD ‘self check’ with a respirometer, the reduction in oxygen causes a definitive pressure difference that can be measured with a pressure sensor. This practical method is very easy to perform.
Both methods require the samples to be incubated at 20ºC for 5 days.
BOD Self check Measurements using OxiTop Control Depletion/Respiration
The Oxitop Control B6/B6M Soil kits are designed for determining the microbial soil respiration according to DIN ISO 16072. Soil respiration is used for forecasting surveying and checking remediation work for biodegradability measurements of pesticides, fungicides and fertilizers and for carrying out toxicity testing.
Soil respiration can be carried out in two different vessel types:
- The OxitopB6M system for actively respiring soils with strong CO2 development the MG 1.0 measuring vessel is used.
- The Oxitop B6 system is the alternative which uses PF 45/500ml sample vessels
Biogas determination is the determination of anaerobic degradation processes using the OxiTop Control AN6/AN12 system.
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, (not supplied). When anaerobic degradation has taken place the dissolved CO2 can be driven off and then removed from the head space by a CO2 absorber. The resulting pressure difference is proportional to the CO2 concentration; the remaining over-pressure is proportional to the methane concentration.