9
BD 600_GB_1 08/2015
1 x BOD base unit with integrated bottle rack
6 x BOD sensor (material ABS)*
6 x BOD bottles
6 x seal cup
6 x magnetic stir bar
3 x battery, alkali manganese ( C / LR14 )
1 x retaining tube for batteries
1 x stirrer drive
1 x mains a primary adapter plug
1 x Y-cable
1 x USB cable
1 x nitrification inhibitor
1 x potassium hydroxide solution (KOH solution)
2 x overflow volumetric flasks (157 ml, 428 ml)
1 x Allen key
1 x operating manual
1 x EC Declaration of Conformity
* for non-aqueous samples: check material compatibility with the sample prior to use.
4 Information about the method
4.1 Biochemical Oxygen Demand (BOD)
The biochemical oxygen demand (BOD) in water (e.g. waste water, surface water) is the amount of
oxygen that is consumed during the degradation of organic substances through biochemical proces-
ses.
4.2 Measuring principle
The BOD measuring unit, comprising test bottle and BOD sensor, is a closed system. With the filled
sample quantity, there is a gas compartment with a defined quantity of air in the test bottle. The bac-
teria in the waste water filled in the bottle (the sample can be used diluted or undiluted) consume the
oxygen dissolved in the sample over the course of the BOD measurement. It is replaced by air oxygen
from the gas compartment of the test bottle. The simultaneously developing carbon dioxide is chemi-
cally bound by the potassium hydroxide in the seal cup of the test bottle. As a result, a pressure drop
occurs in the system, which is measured by the BOD sensor and shown in the directly in the display as
a BOD value in mg/l O
2
.