TBC 3013

INFORMATION AND COMMUNICATION TECHNOLOGY IN BIOLOGY

DATA LOGGING REPORT

“BIOCHEMICAL OXYGEN DEMAND”

GROUP MEMBERS

NOOR FARA ERMA BT ABDUL ILLAHI D20081032283NORASILAH BT ABDUL BARI D20081032254AIN NABILAH BT DAUD D20081032300ROBIAH BINTI ROMLI D20081032316

LECTURERS’S NAME: DR SADIAH BINTI BAHAROM

CIK SITI SHAMSIAH BINTI SANI

Title: Measuring the B.O.D value in different water sample

Introduction:

Natural sources of organic matter include plant decay and leaf fall. However, plant

growth and decay may be unnaturally accelerated when nutrients and sunlight are overly

abundant due to human influence. Urban runoff carries pet wastes from streets and sidewalks;

nutrients from lawn fertilizers; leaves, grass clippings, and paper from residential areas, which

increase oxygen demand. Oxygen consumed in the decomposition process robs other aquatic

organisms of the oxygen they need to live. Organisms that are more tolerant of lower

dissolved oxygen levels may replace a diversity of natural water systems contain bacteria,

which need oxygen (aerobic) to survive. Most of them feed on dead algae and other dead

organisms and are part of the decomposition cycle. Algae and other producers in the water

take up inorganic nutrients and use them in the process of building up their organic tissues.

Consumers like fish and other aquatic animals eat some of the producers, and the

nutrients move up the food chain. When these organisms die, bacteria decompose the organic

compounds and release into the water inorganic nutrients such as nitrate, phosphate, calcium,

and others. Some of these nutrients end up down stream or in sediments, but most of them

recycle again and again. Most of the bacteria in the aquatic water column are aerobic. That

means that they use oxygen to perform their metabolic activities of decomposition. The

presence of organics and other oxygen consuming materials reduces oxygen content and

compromises water quality. Thus, the higher value of B.O.D, the lower water quality that we

have.

Objectives:

1. To measure the dissolved oxygen in different water sample

2. To calculate the B.O.D value

3. To determined the 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

Apparatus and Material:

Beaker 250 mL, five samples of water from different sources, a computer with a Excel

Spreadsheet Program, D.O sensor, data logger and distilled water.

Procedures:

1. 100 mL of pond water is collected in a beaker

2. The beaker is labeled with P

3. The D.O sensor is put into the beaker

4. The D.O value is recorded

5. Step 1 to 3 are repeated using water from different sources that are drain water,

distilled water, aquarium water and pipe water. The beakers are labeled as Q, R, S, T

respectively

6. Before put the sensor into the next sample of water, the sensor is rinsed with distilled

water.

7. The B.O.D value is calculated by using Excel Spreadsheet Program

8. The apparatus are set up as the figure below

Result:

Time(s)0 5 10 15 20 25 30 35 40 45

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Calculation

Water samples Initial DO(mg/L) Final DO(mg/L) B.O.DDrain water 3.6 4.563 0.963Distilled water 4.263 4.675 0.412Pond water 3.975 4.625 0.65Aquarium water 3.725 4.588 0.863Pipe water 4.1 4.638 0.538

Discussion:

Microorganisms such as bacteria are responsible for decomposing organic waste.

When organic matter such as dead plants, leaves, grass clippings, manure, sewage, or even

food waste is present in a water supply, the bacteria will begin the process of breaking down

this waste. When this happens, much of the available dissolved oxygen is consumed by

aerobic bacteria, robbing other aquatic organisms of the oxygen they need to live.

Biological Oxygen Demand (BOD) is a measure of the oxygen used by

microorganisms to decompose this waste. BOD is a chemical procedure for determining the

rate of uptake of dissolved oxygen by the rate biological organisms in a body of water use up

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

quality of water.

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 (due to all the bacteria) so the BOD level will be high. As the waste is consumed or

dispersed through the water, BOD levels will begin to decline.

Nitrates and phosphates in a body of water can contribute to high BOD levels. Nitrates

and phosphates are plant nutrients and can cause plant life and algae to grow quickly. When

plants grow quickly, they also die quickly. This contributes to the organic waste in the water,

which is then decomposed by bacteria. This results in a high BOD level. The temperature of

the water can also contribute to high BOD levels. For example, warmer water usually will

have a higher BOD level than colder water.

As water temperature increases, the rate of photosynthesis by algae and other plant life

in the water also increases. When this happens, plants grow faster and also die faster. When

the plants die, they fall to the bottom where they are decomposed by bacteria. The bacteria

require oxygen for this process so the BOD is high at this location. Therefore, increased water

temperatures will speed up bacterial decomposition and result in higher BOD levels.

When BOD levels are high, dissolved oxygen (DO) levels decrease because the oxygen that is

available in the water is being consumed by the bacteria. Since less dissolved oxygen is available in

the water, fish and other aquatic organisms may not survive.

BOD Level(in ppm)

Water Quality

1 - 2Very GoodThere will not be much organic waste present in the water supply.

3 - 5 Fair: Moderately Clean

6 - 9Poor: Somewhat PollutedUsually indicates organic matter is present and bacteria are decomposing this waste.

100 or greater Very Poor: Very PollutedContains organic waste.

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 macroinvertebrates 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 mayfly nymphs) will

NOT survive.

Dissolved oxygen (DO) is the amount of oxygen that is dissolved in water and is

essential to healthy streams and lakes. The dissolved oxygen level can be an indication of how

polluted the water is and how well the water can support aquatic plant and animal life.

Generally, a higher dissolved oxygen level indicates better water quality. If dissolved oxygen

levels are too low, some fish and other organisms may not be able to survive (see

macroinvertebrates).

Much of the dissolved oxygen in water comes from oxygen in the air that has

dissolved in the water. Some of the dissolved oxygen in the water is a result of photosynthesis

of aquatic plants. Other factors also affect DO levels such as on sunny days high DO levels

occur in areas of dense algae or plants due to photosynthesis. Stream turbulence may also

increase DO levels because air is trapped under rapidly moving water and the oxygen from

the air will dissolve in the water.

In addition, the amount of oxygen that can dissolve in water (DO) depends on

temperature. Colder water can hold more oxygen in it than warmer water. A difference in DO

levels may be detected at the test site if tested early in the morning when the water is cool and

then later in the afternoon on a sunny day when the water temperature has risen. A difference

in DO levels may also be seen between winter water temperatures and summer water

temperatures. Similarly, a difference in DO levels may be apparent at different depths of the

water if there is a significant change in water temperature.

Dissolved oxygen levels typically can vary from 0 - 18 parts per million (ppm) although most

rivers and streams require a minimum of 5 - 6 ppm to support a diverse aquatic life. Additionally, DO

levels are sometimes given in terms of Percent Saturation. However for this project, the results will

be reported in ppm (if you wish to determine the Percent Saturation, you can use this DO Percent

Saturation chart).

DO Level(in ppm)

Water Quality

0.0 - 4.0PoorSome fish and macroinvertebrate populations will begin to decline.

4.1 - 7.9 Fair

8.0 - 12.0 Good

12.0 + RetestWater maybe artificially aerated

At 20º C (room temperature) and standard atmospheric pressure (sea level), the

maximum amount of oxygen that can dissolve in fresh water is 9 ppm. If the water

temperature is below 20º C, there may be more oxygen dissolved in the sample. In general, a

dissolved oxygen level of 9-10 ppm is considered very good.

At levels of 4 ppm or less, some fish and macroinvertebrate populations (e.g. bass,

trout, salmon, mayfly nymphs, stonefly nymphs, caddisfly larvae) will begin to decline. Other

organisms are more capable of surviving in water with low dissolved oxygen levels (i.e.

sludge worms, leeches). Low DO levels may be found in areas where organic material (dead

plant and animal matter) is decaying. Bacteria require oxygen to decompose organic waste,

thus, deplete the water of oxygen. Areas near sewage discharges sometimes have low DO

levels due to this effect. DO levels will also be low in warm, slow moving waters.

Based on our experiment the most polluted water is drain water followed by aquarium

water, pond water, pipe and distilled water.

Conclusion:

As a conclusion, our hypothesis for this experiment is accepted.

ENGAGE

RIVER A RIVER B

Science students from a school make the visited to the two of the river around Tanjung Malim

to complete their task in doing experiment to study the sample of the river water. However,

they are found that one of the rivers has been polluted and many fishes died while another

river has very clear and clean water. So, they took both of the river water samples and study

the content of the water. In your opinion, how could the fishes died? How to prevent this

problem from occurred?

From your observation, what are differences between river A and river B?

Which river has the low content of the oxygen?

Why? Explain.

EMPOWER

Steps:

1. Students are given:

Beaker 250 ml

Five samples of water from different sources

A computer with a (Excel Spreadsheet Program)

2. Students should know and construct the experiment to analyzing data on water

pollution

3. Students also were guided to get the right variable and the right data

4. They have to construct a hypothesis for this experiment.

5. Teacher may give these instructions to start the activity:

Collect 100 mL of pond water in a beaker

Label the beaker with P

Put the sensor into the water

Record the B.O.D value

Repeat step 1 to 3 using water from different sources that are drain water,

distilled water, aquarium water and pipe water. Label the beaker as Q, R, S, T

respectively

Before put the sensor into the next sample of water, rinse the sensor with

distilled water.

Record the data using Excel Spreadsheet Program

ENHANCE

THINGS TO PONDER

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

FIGURE A FIGURE B

2. What are the effects of this phenomenon?

3. Give on way to solve the problem.

ANSWER

1. Oil spill in the sea.

2. -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.

3. 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.