TBC 3013 INFORMATION AND COMMUNICATION TECHNOLOGY IN BIOLOGY DATA LOGGING REPORT “BIOCHEMICAL OXYGEN DEMAND” GROUP MEMBERS NOOR FARA ERMA BT ABDUL ILLAHI NORASILAH BT ABDUL BARI AIN NABILAH BT DAUD ROBIAH BINTI ROMLI
LECTURERS’S NAME: BAHAROM
D20081032283 D20081032254 D20081032300 D20081032316
DR SADIAH BINTI
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:
5
4.5 Calculation Water samples Drain water Distilled water Pond water Aquarium water Pipe water
Initial DO(mg/L) 3.6 4.263 3.975 3.725 4.1
4
Final DO(mg/L) 4.563 4.675 4.625 4.588 4.638
B.O.D 0.963 0.412 0.65 0.863 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
Water Quality
(in ppm)
1-2 3-5 6-9 100 or greater
Very Good There will not be much organic waste present in the water supply.
Fair: Moderately Clean Poor: Somewhat Polluted Usually indicates organic matter is present and bacteria are decomposing this waste.
Very Poor: Very Polluted Contains 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
Water Quality
(in ppm)
0.0 - 4.0 4.1 - 7.9
Poor Some fish and macroinvertebrate populations will begin to decline.
Fair
8.0 - 12.0
Good
12.0 +
Retest Water 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?
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Which river has the low content of the oxygen?
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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
FIGURE A
FIGURE B
THINGS TO PONDER 1. From the picture above, what are the phenomenon occurred? ANSWER 2. What are the effects of this phenomenon? 1. Oil spill in the sea. 3. Give on way to solve the problem. 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.
