Hanna Instruments HI 98186 - Manual (Page 15)

15
BOD MEASUREMENTS
Biochemical oxygen demand (BOD) is an indicator for the concentration of
biodegradable organic matter present in a sample of water. It can be used to
infer the general quality of the water and its degree of pollution. BOD
measures the rate of oxygen uptake by microorganisms in a sample of water
at a fixed temperature and over a given period of time. To ensure that all
other conditions are equal, a very small amount of microorganism seed is
added to each sample being tested. This seed is typically generated by
diluting activated sludge with deionized water. The samples are kept at 20 ºC
in the dark and tested for dissolved oxygen (DO) after five days. The loss of
dissolved oxygen in the sample, once correction have been made for the degree
of dilution, is called the BOD
5
Before measuring BOD, remember to set the BOD configuration from the
SETUP menu (see page 33).
Press RANGE to access the BOD measure screen.
Press BOD Data to view the BOD initial data management screen.
Press Compute to evaluate the BOD for a specified sample (available only
when the measurement is stable and at least one initial BOD data record has
been memorized).
BOD initial data management screen
BOD Data is pressed while in BOD measurement screen.
Press Add new to add a new BOD initial data record (the key is available only
when the measurement is stable). A 200 records memory space is available
for BOD initial data.
Press View ID to view the saved BOD initial values (the key is available only