1. The document describes an experiment to determine the biochemical oxygen demand (BOD) of various water samples using data loggers. 2. Samples of pond water, drain water, distilled water, aquarium water, and pipe water were tested by recording the initial and final dissolved oxygen concentrations over 5 days. 3. The BOD value, which indicates how polluted the water is, was calculated using the difference between initial and final dissolved oxygen levels. The higher the BOD value, the more polluted the water sample.

1. DEPARTMENT OF BIOLOGY
FACULTY OF SCIENCE & MATHEMATICS
UNIVERSITI PENDIDIKAN SULTAN IDRIS
INFORMATION AND COMMUNICATION TECHNOLOGYIN BIOLOGY
(SBI3013)
DATA LOGGER:
BIOCHEMICAL OXYGEN DEMAND (B.O.D)
NAME MATRIC NO.
NOR AZWAHANIN BINTI ABU HASSAN D20152071976
NOR HIDAYAH BINTI ISMAIL D20152071972
AZIDA BINTIMD ZIN D20152071993
GROUP : A
LECTURER: ENCIKAZMI BIN IBRAHIM

2. Objective:
1. To identify the BOD using data logger.
2. To determine biochemical oxygen demand in the given water sample.
3. To perform a basic experiment to determine the water quality of a given system based on
biochemical oxygen demand (BOD)
4. To determine most polluted water sample.
Hypothesis
The higher B.O.D value, the more polluted the source of water.
Variables
1. Manipulated : Sample of water
2. Responding : Dissolved oxygen value
3. Constant : Volume of water sample
Introduction
The biochemical oxygen demand determination is a chemical procedure for determining the
amount of dissolved oxygen needed by aerobic organisms in a water body break the organic
materials present in the given water sample at certain temperature over a specific period of time.
BOD of water or polluted water is the amount of oxygen required for the biological
decomposition of dissolved organic matter to occur under standard condition at a standardized
time and temperature. Usually, the time is taken as 5 days and the temperature is 20˚ C.
The test measure the molecular oxygen utilized during a specified incubation period for the
biochemical degradation of organic material (carbonaceous demand) and the oxygen used to
oxidize inorganic material such ass sulfides and ferrous ion. It also may measure the amount of
oxygen used to oxide reduced forms of nitrogen (nitrogenous demand).

3. We take sample of water at pond water, drain water, distilled water, aquarium water and
pipe water. So we use data logger to get the result from the entire water sample. Therefore, BOD
value is determined by the following formula:
Where:
D1= initial DO in a sample
D1=final DO in a sample
B2= initial DO in blank
B2= final DO in blank
P = fraction of the BOD bottle that is represented by the sample.
Apparatus
Beaker, D.O Probes @ Dissolve oxygen meter (sensor), Computer with Data Logger Spreadsheet
Program.
Materials
Pond water, drain water, distilled water, aquarium water and pipe water.
Procedure
1) 5 beakers were labeling with A, B, C, D and E.
2) 100mL of pond water are collected and pour into beaker A.
3) *the D.O probe was placed in the beaker A to read the initial D.O concentration directly.
4) The result was recoded in Data Logger Spreadsheet Program.
5) steps 1 to 4 were repeated by using different samples of water which are drain water,
distilled water, aquarium water and pipe water which the samples of water is poured into
beaker B, C, D and E respectively.
6) The samples were let until 5 days and D.O probes were placed again in these samples to
read the final D.O concentration.
BOD value in mg/l=[(D1-D2) – (B2-B2)/P

4. 7) BOD value was determined by the following formula:
*Note that, before put the sensor into the next sample of water, rinse the sensor with
distilled water.
B.O.D value = Final D.O- Initial D.O
p