DEPARTMENT OF SCIENCE

FACULTY OF SCIENCE AND MATHEMATICS

UNIVERSITI PENDIDIKAN SULTAN IDRIS

ASSIGNMENT (DATA LOGGER)SSI3013 : INFORMATION COMMUNICATION

AND TECHNOLOGY Semester I Session 2012/2013

NAME AND ID NUMBER 1. NUR WAHIDAH BT SAMI’ON D20101037525

2. NOR HASHIMAH BT ZAITONG D20101037458

3.NUR ASHIKIN BT ALIAS D20101037459

LECTURER : MR.AZMI BIN IBRAHIM

GROUP : B

DATE OF SUBMITTED : 03 December 2012

Title : Biochemical Oxygen Demand (B.O.D)

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Objectives :

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 water2. Responding : Dissolved oxygen value3. Constant : Volume of water sample

Introduction:

Data logger is a device such as lab instrument to record all data generated or the data

passing through a particular point in a networked computer system. It can record a wide variety

of energy and environmental measurements including temperature, relative humidity, light

intensity, oxygen dissolve (DO), water level and soil moisture. Data loggers are used in a broad

range of indoor, outdoor and underwater environments that essentially anywhere data is needed

and the convenience of battery power is preferred.

Figure 1: BOD data logger

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Biochemical oxygen demand or B.O.D is a chemical procedure for determining the

amount of dissolved oxygen needed by aerobic organisms in a water body to break the organic

materials present in the given water sample at certain temperature over a specific period of time.

It is not a precise quantitative test, although it is widely used as an indication of the quality of

water. 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 measures the molecular oxygen utilized during a specified incubation period for

the biochemical degradation of organic material (carbonaceous demand) and the oxygen used to

oxidize material such as sulfides and ferrous ion. It also may measure the amount of oxygen used

to oxidize reduced forms of nitrogen (nitrogenous demand).

The BOD test is widely used to determine the pollution strength of domestic and

industrial wastewaters in terms of the oxygen that they will require if discharged into natural

watercourses in which aerobic conditions exist. The test is one of the most important both in

regulatory work and in studies designed to evaluate the purification capacity of receiving water

bodies.

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:

BOD value in mg/l = [(D1-D2) – (B1-B2)] /P

Where;

D1= initial DO in a sample

D2= final DO in a sample

B1= initial DO in blank

B2= final DO in blank

P= fraction of the BOD bottle that is represented by the sample

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Apparatus:

Beaker, D.O Probes @ Dissolves 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) 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 was 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.

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.

Results and Data:

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Initial DO (mg/L) Final DO(mg/L)

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Analysis:

From the graph above, there are five different colour lines of graph means that, it has five

different water samples. 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.

From this graph, it 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. Beside that, from the graph shows the BOD level will increase over the

time. It can be said that the BOD level is directly proportional to the time.

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Discussion:

Biological Oxygen Demand (BOD) is a measure of the amount of oxygen that bacteria will

consume while decomposing organic matter under aerobic conditions. BOD is determined by incubating a

sealed sample of water for five days and measuring the loss of oxygen from the beginning to the end of

the test. Samples often must be diluted prior to incubation or the bacteria will deplete all of the oxygen in

the bottle before the test is complete.

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.

In this experiment, drain water have been identified have high BOD level may be due to the large

amount of the microorganisms to decompose waste. In drain have a lot of waste from many different

sources such as waste from house and farming area. All this types of microorganism working together to

decompose waste and will cause large number of oxygen demand. On the other hand, the distilled water

shows low BOD level. This case was due to the small amount of microorganisms and causes the oxygen

demand to be low.

In the farming area, there presents the inorganic substances like nitrates and phosphates from the

fertilizer that was used by the farmer. The nitrates and phosphorus in a body of water can contribute to

high BOD levels. These nutrients are essential for the growth of algae and other plants. Aquatic life is

dependent upon these photosynthesizers, which usually occur in low levels in surface water. Excessive

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concentrations of nutrients can over stimulate aquatic plant and algae growth. Bacterial respiration and

organic decomposition can use up dissolved oxygen.

Fertilizers, failing septic systems, waste water treatment plant discharges, and wastes from pets

and farm animals are typical sources of excess nutrients in surface waters. In aquatic ecosystems,

because phosphorous is available in the lowest amount, it is usually the limiting nutrient for plant growth.

This means that excessive amounts of phosphorous in a system can lead to an abundant supply of

vegetation and cause low DO. Increased nitrogen levels adversely affect cold-water fish more than they

do warm water fish.

In addition, metabolic rate and the reproductive activities of aquatic life are controlled by water

temperature. Metabolic activity increases with a rise in temperature, thus increasing a fish demand for

oxygen. Temperature of water also can increase and cause to high BOD level. Therefore, warmer water

usually has high BOD level than colder water. When the water temperature increases, the rate of

photosynthesis by algae and other plant life in the water also increases. When this situation happens, it

can make plant die faster and they will fall to the bottom of the water body so that they can be

decomposed by bacteria. Therefore, increased water temperatures will speed up bacterial decomposition

and result to high BOD levels. A rise in temperature also can provide conditions for the growth of disease

causing organisms.

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.

Therefore, from the result obtained the most polluted water is drain water which have high level

of BOD compare to the other water sample. Drainage water is no different from any other water supply

and is always usable for some purpose within certain quality ranges. Beyond these limits, drainage water

must be disposed of in a manner that safeguards the usability or quality of the receiving water for present

established and potential uses.

Surface and subsurface drainage water from agriculture is normally degraded compared

with the quality of the original water supply. Drainage water that flows over or through the soil

will pick up a variety of dissolved and suspended substances including salts, organic compounds

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and soil particles. Management for safe reuse and disposal requires an understanding of the

characteristics of the drainage water, and a matching of those characteristics to the environmental

protection needs of the reuse or disposal area. Sometimes, characteristics of drainage water have

a potential on environmental contaminant.

Conclusion:

The drain water has high BOD level which is 0.963 mg/L while, the lowest BOD level is distilled

water with the value 0.412 mg/L. It can be identified that the high BOD level of water is the most

polluted.

Enhance

The chemical, physical, and biological aspects of water quality are interrelated and must be

considered together. For example, higher water temperature reduces the solubility of dissolved oxygen,

and may cause a dissolved oxygen shortage that kills more sensitive fish species. The rotting fish

carcasses may contribute to a bacterial bloom that makes some human swimmers or boaters ill.

Water quality is highly variable over time due to both natural and human factors. Water

temperature, photosynthetic activity, and flows vary with season. Therefore, the flow and suspended

sediment can vary daily with rainfall. Nutrients loads can vary with season like homeowners fertilizing in

the spring flow from the runoff mechanisms affect pollutant washoff and human management like

nitrogen is released after a clear cut.

Question:

Figure 1 Figure 2

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1. From the picture above, what are the phenomenon occurred?

Oil spill in the sea.

2. What are the sources of pollution?

-Careless discharge of water heated, for example industrial places.

-Removal of shading vegetation.

3. What are the effects of this phenomenon?

-The effect on this phenomenon is oil spills can have widespread effects on nearly all

Creatures that come into contact with it, from algae to migratory birds, to marine

mammals.

-The main problem caused by water pollution is that it kills life that inhabits water-based

ecosystems. Dead fish, birds, dolphins, and many other animals often wind up on

beaches, killed by pollutants in their habitat.

-Pollution disrupts the natural food chain as well. Pollutants such as lead and cadmium

are eaten by tiny animals. Later, these animals are consumed by fish and shellfish, and

the food chain continues to be disrupted at all higher levels.

-Eventually, humans are affected by this process as well. People can get diseases such as

Hepatitis by eating seafood that has been poisoned.

-Ecosystems can be severely changed or destroyed by water pollution. Many areas are

now being affected by careless human pollution, and this pollution is coming back to

hurt humans.

4. Give one way to solve the problem.

Bioremediation is the process that uses microorganisms, fungi, green plants or their

enzymes to return the natural environment altered by contaminants to its original

condition. In general approach is the cleanup of oil spills by the addition of nitrate or

sulfate fertilizers to facilitate the decompositions of crude oil by bacteria.

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References:

Delft (1999). Understanding biochemical oxygen demand test. New Delhi: India.

G.C Delzer and S.W. McKenzie (2003). Five days biochemical oxygen demand. United

States.

https://docs.google.com/present/view?id=djc74gw_201d7z7z3gj

http://www.mpcd.info/index.php?

option=com_content&view=article&id=158&Itemid=145

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