1. SSI3013 : ICT IN SCIENCE
DATA LOGGER : B.O.D
NO. NAME MATRIC NO.
1 NOR HASHIMAH BINTI ZAITONG D20101037458
2 NUR ASHIKIN BINTI ALIAS D20101037459
3 NUR WAHIDAH BINTI SAMI’ON D20101037525

2. Biochemical Oxygen
Demand
(B.O.D )

3. BOD
The biochemical oxygen demand is
defined as the ‘measure of dissolve
oxygen require to decompose the
organic matter in water biologically.
Pure water has < 1ppm
Polluted water >5ppm

4. ENGAGE
RIVER A RIVER B

5. UPSI student make visited to 2 river
They found that one of the
around Tg. Malim to complete their
river polluted and more fish
task in doing exp. To study the
died .
sample of river of water
So they took the
The other river sample of the river and In your opinion
has clean and study the content of why fish died??
clear water. the water.

6. Higher BOD, means that there is dissolved
oxygen in the water, as aerobic bacteria uses up
nearly all of it for respiration.
Hence less dissolved oxygen available for the fish
to use for respiration, So fish will died.

7. From your observation what is deference
between river A and river B?
Which water has low content of the
oxygen ? why??

8. EMPOWERING
FIGURE 1 FIGURE 2

9. PROCEDURE
1. 5 beaker were labelling with A, B, C, D and E.
2. 100 mL 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 were recorded 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.

10. 6. The samples were let until 5 days and D.O probes was
placed again in these samples to read the final D.O
concentration.
7. BOD value was determined by the following formula:
B.O.D value = Final D.O – Initial D.O
p
*Note that, before put the sensor into the next sample of
water, rinse the sensor with distilled water.

11. RESULTS

12. • The blue line represents drain water. The red line
represents aquarium water. The pink line
represents pond water. The green line represents
pipe water. The last purple line represents
distilled water. This graph shows the BOD
(Biological Oxygen Demand) level of the water
sample against time.
• Graph shows the drain water have the highest
BOD level which is 0.963mg/l. While, the lowest
BOD level is distilled water which have 0.42 mg/l.
• This shows that the most polluted water sample
is drain water followed by aquarium water
sample, pond water, pipe water and the less
polluted water sample is distilled water.

13. Beaker Water samples Initial D.O Final D.O B.O.D value
(mg/L) (mg/L) (mg/L)
A Drain water 3.6 4.563 0.963
B Distilled water 4.263 4.675 0.412
C Pond water 3.975 4.625 0.65
D Aquarium water 3.725 4.588 0.863
E Pipe water 4.1 4.638 0.538

14. • The very important thing to know is the dissolve oxygen (DO)
content of the sample to measuring the BOD of a water sample. The
amount of DO in water affects natural biochemical processes in two
ways where by limiting the amount of oxygen available for
respiration and by affecting the solubility of essential nutrient in the
water sample. The decomposition of organic matter is the greatest
factor in the depletion of available oxygen in water body. As the
organic content in water increase, there is a corresponding increase
in bacterial activity and decrease the dissolved oxygen content.
• The microorganisms such as bacteria are responsible for
decomposing organic waste. When the organic matter such as dead
plants, leaves, grass clippings, manure, sewage, and food waste also
present in a water supply. This will support the bacteria to begin
process of breaking down the waste. This situation can cause more
available dissolve oxygen was consumed by aerobic bacteria,
robbing other aquatic organisms that need oxygen to live.
• If there is a large quantity of organic waste in the water supply, there
will also be a lot of bacteria present working to decompose this
waste. In this case, the demand for oxygen will be high in the water
sample due to the bacteria will cause the BOD level will be high. As
the waste was consumed or dispersed through the water sample,
BOD level will begin to decline.

15. • As the BOD level is high, dissolved oxygen (DO)
level will decrease because the oxygen available
in water is being consumed by microorganisms in
the water. Since less dissolved oxygen is available
in the water, organisms such as fish, caddisfly
larvae and mayfly nymphs and other aquatic
organisms cannot survive. This will cause the
aquatic organisms become extinct over the time.
At high BOD levels, organisms such as
macroinvertebrates that are more tolerant of
lower dissolved oxygen such as leeches and
sludge worms may appear and become
numerous.

16. • NOTE: Generally, when BOD levels are high, there is a
decline in DO levels. This is
• because the demand for oxygen by the bacteria is high
and they are taking that oxygen from the oxygen
dissolved in the water. If there is no organic waste
present in the water, there won't be as many bacteria
present to decompose it and thus the BOD will tend to
be
lower and the DO level will tend to be higher.
• At high BOD levels, organisms such as macro
invertebrates that are more tolerant of lower dissolved
oxygen (i.e. leeches and sludge worms) may appear
and become numerous. Organisms that need higher
oxygen levels (i.e. caddisfly larvae and mayflynymphs)
will NOT survive.

18. ENHANCE

19. Optimization
biological
carbon and
nitrogen
removal
Enhance
Aerobic Municipal
biological waste water
treatment treatment
process plant

20. CONCLUSION
• BOD will increase because of the presents
aerobic microorganism
• High BOD give potential to water pollution
• Ways to overcome:
-Individual awareness
-Government responsibilities