Env. Eng. Lab Manual

7/29/2019 Env. Eng. Lab Manual

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Faculty of Engineering, Technology

And Built Environment

Section Total (%) Criteria Score Remark

Introduction 10%

Contain a concise summary of the experiment that is carried out. Includes the statement

of purpose, an introduction into technique used and a brief overview of the

instrumentation.

Materials &

methodology10%

Contains all relevant experimental procedures, materials and instrument parameters used

in the analysis or during the experiment.

Results /Collected

Data30%

Show all the measured value from the experiment. All measured value must be expressed to

correct significant figures and in correct units. (assess by observation)

Discussion/Analysis 30%

Well laid out and calculated analysis based on collected data. Graph/Simulation (if needed) and

have appropriate calculations showing relationship/comparison of measured value, simulation

value and calculation. (assess by lab report)

Conclusion 10%Conclusion should reflect an understanding of the subject theory involved and achievement of the

experiment objective. (assess by lab)

Format 10% Reference, Front page, table of content, graph, figure, table, etc. (assess by lab)

100% Total Score

Lab Report Rubric (Assessment Form)

Student Name:

Student ID:

Experiment Title:


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Experiment 1

Air Pollution: Rain Fall Analysis

Purpose

To determine the different pH of the rainwater samples collected from different location

(residential area, commercial area or industrial area).

To investigate the difference between the acidity of rain that falls directly on the open lake or

passing through the ground.To determine the presence of sulphur acid and nitric acid of the rainwater sample using IR.

Theory

Rain falling through a perfectly unpolluted atmosphere will arrive at the earth with a pH of about

5.6. This is because of the carbon dioxide in atmosphere reacts with the rain water these reactions:

33222 HCOHCOHOHCO

This small amount of acidity is sufficient to dissolve and provide to plant and animal life; yet not

acidic enough to inflict any damage. Atmosphere substances from volcanic eruptions, forest fires,

and other similar natural phenomena also contribute to the natural sources of acidity in rain but not

too acidic.

Acid rain is defined as any type of precipitation with a pH below 5.6. Acid rain has been associated

with sulphur oxide (SOx) and nitrogent oxide (NOx) which combining with oxygen to form sulphur

dioxides and nitrogen dioxides. These gases react with water to form sulphuric and nitric acids which

are soluble and fall with the rain.


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Acid rain major sources are from human sources, such as industrial and power generating plants,

automobiles and industries. Winds may spread these acidic solutions across the atmosphere and

over hundreds of miles. When acid rain reaches Earth, it flows across the surface in runoff water,

enters water systems, and sinks into the soil.

Acid rain affected both human and nature. Acid rain can cause buildings, statues and bridges to

deteriorate faster than usual. It also will disrupt aquatic ecosystems. Acid rain also damages soil and

the tree roots in it. Another problem is it will harm people directly and indirectly such as when

breathing in smog, or taking in aquatic life which already been polluted by acid rain.

Methodology

A. Material & Apparatus Preparation

1. pH test kit2. IR Spectrometer3. Collection container (plastic bottles).4. Filter paper5. Soil sample (from garden or backyard)

B. Procedure

1.Cut the 2L bottles into two separate halves (see diagram). The tophalf of the bottle is the FUNNEL. The bottom half is the COLLECTION CONTAINER. Remove the cap

from the funnel. Do not discard cap. DO NOT use an aluminum or tin container.


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2. Place the COLLECTION CONTAINER in an open area (residential area & industrial area/commercial

area) for RAINWATER SAMPLE collection.

3. Measure the pH of the RAINWATER SAMPLE. Record the data.

4. Place filter paper into the FUNNEL (see diagram).

5. Carefully pour the soil sample into the filters in the FUNNEL. Be careful not to

pour the soil in between the funnel and the filters.

6. Hold FUNNEL directly over the COLLECTION CONTAINER.

7.Slowly pour the RAINWATER SAMPLE into the FUNNEL. Again, keep the soil/rainwater solutionfrom pouring over the sides of the filters and getting in between the filters and the funnel.

8.Allow the entire RAINWATER SAMPLE to flow through the filter and collect in the COLLECTIONCONTAINER.

9.It may be necessary, depending on soil type, to filter twice. The filtered rainwater sample shouldbe fairly colorless.

10. Measure the pH level of the filtered rainwater sample, record, and compare this to the pH

measurement of the unfiltered rainwater sample.


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11. By using IR Spectrometer, measure the presence of sulphur acid and nitrogen acid for all

the RAINWATER SAMPLES as well as after filtration.

Remarks: Label all the Collection Container

Result & Discussion

1. Compare your results based on the RAINWATER SAMPLE from residential area and industrial

area/commercial area. Discuss your result.

2. Compare your results based on the RAINWATER SAMPLE before filtration and after filtration and

passing through the soil. Discuss your result.

3. Justify is sulphur acid and nitrogen acid of the sample.

4. Suggest one control method to avoid acid rain in the industrial activity.

Reference:

Measuring Acid Rain (2007) U.S. Environmental Protection Agency. Accessed on 15 Dec 2010 from

http://www.epa.gov/acidrain/measure/index.html


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Experiment 2

Analysis of Water Samples

Purpose

To determine the hardness of the water samples.

Theory

Hardness of water is a property caused by the presence of polyvalent metal cations, primarily Ca2+

and Mg2+

in natural waters. Hardness is undesirable in a water supply because it results in scale

formation and in soap wastage. It can be easily removed by boiling the water or by adding lime to

water. Total hardness of water is composed of two components: temporary and permanenthardness. The temporary hardness is due to the presence of carbonates and bi-carbonates of

calcium and magnesium. The permanent hardness is due to the presence of sulphates, chlorides and

nitrates of calcium and magnesium. It requires special methods of water softening. Hardness is

expressed in part per million or commonly known as ppm.

Water with hardness up to 50ppm is known as softwater. 50-150ppm it is termed as medium and

150-300 ppm is termed as moderately hard water. If the hardness is more than 300 ppm it is know

as hard water. Total hardness is commonly found by determining the amount of calcium and

magnesium by gravimetric analysis and by calculating their equivalent values in terms of CaCO3.

Hardness determination uses one of the most common agents: ethylene-diamine-tetra-acetic acid

(EDTA). Disodium ethylene-diamine-tetra-acetic acid (Na2EDTA) forms stable complex ions with Ca2+

,

Mg2+

, and remove them from solution. When small amount of dye is added to the water containing


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hardness ions at pH10, the solution becomes wine red and if there is no hardness the colour is blue.

With the addition of EDTA the water sample having indicator dye starts forming stable complexes.

Methodology

A. Samples Preparation

1. Tap water

2. Water sample to analyze for total hardness.

B. Reagents Preparation

1. Standard EDTA solution: 0.01 M (1 mL = 1 mg hardness as CaCO3): Dissolve 3.723 g disodium-

ethylenediamine-tetraacetate-dihydrate in distilled water and dilute to 1 liter. (Approximately 200

mL per group).

C. Procedure to Test Total Hardness

The Blank and Titration Procedure

In order to correct for any error attributable to the deionized water and the indicator color

transition, you will be analyzing a blank solution. The volume of EDTA used to titrate the blank will

be subtracted from all other titration volumes.

1. Pipette a 50.00 mL sample of deionized water into a clean 250 mL Erlenmeyer flask.

2.Add about 1mL of ammonia buffer, using a 10mL graduated cylinder. At this point heat the flaskon the hot plate until condensation forms on the inside rim of the flask. Immediately add a few


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drops of indicator. If the solution turns blue, there is no measurable calcium or magnesium in

solution and you will not have a blank correction.

If the solution stays red or violet, immediately start titrating with the EDTA solution. Titrate until

there is no trace of red or violet in your solution. Be sure to go drop wise as you approach the

endpoint. The kinetics of the indicator reaction are slow; heating aids in speeding up the transition

from red to blue. However, it is necessary to titrate slowly as you approach the endpoint so that it is

not overshot. The color change upon reaching the endpoint for this titration is subtle.

Unknown water sample titration

1. Repeat the above procedure, substituting 10.00 mL portions of your unknown sample, in place of

the 50.00 mL deionized water sample.

2. Measure 50 mL sample 1 into a 250 mL beaker. Add 1-2 mL buffer solution. The pH should be

10.0 0.1.

3. Add 1-2 drops EBT indicator.

4. Titrate to a blue color. The duration of the titration should not exceed 5 minutes. Record thevolume of EDTA before titration as C1 and after titration as C2.

The net volume of EDTA required by sample should be C=C1-C2

5 Repeat the step 1-5 for tap water.

Result & Discussion

1. Data collection

Sample Volume of

sample

Initial reading of

burette

Final

reading

mL of EDTA

Sample 1 C1

C2

Sample 2 C1

C2


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2. Calculation of Total Hardness:

Hardness is expressed as parts per million of equivalent CaCO3. For example, if the titration required

5 mL EDTA, the calculation would be:

Report the total hardness of each sample.

3. Why the hardness of the water is important to be known. Give an example.

Reference:

Standard Methods for the Examination of Water and Wastewater, 20th ed., L.

S. Clesceri, A. E. Greenberg, A. D. Eaton editors, 1998, American Public Health

Association.


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EXPERIMENT 3

Turbidity and the Dissolve Oxygen

Purpose

To demonstrate the relationship of turbidity level with coagulation process by using chemical

application.

To investigate the relationship of turbidity levels with the levels of dissolve oxygen.

Theory

Turbidity is a measurement of how cloudy water appears. Technically, it is a measure of how much

light passes through water, and it is caused by suspended solid particles that scatter light. These

particles may be microscopic plankton, stirred up sediment or organic materials, eroded soil, clay,silt, sand, industrial waste, or sewage. Bottom

sediment may be stirred up by such actions as waves or currents, bottom-feeding fish, people

swimming, or wading, or storm runoff. Clear water may appear cleaner than turbid water, but it is

not necessarily healthier. Water may be clear because it has too little dissolved oxygen, too much

acidity or too many contaminants to support aquatic life. Water that is turbid from plankton has

both the food and oxygen to support fish and plant life. However, high turbidity may be a symptom

of other water quality problems.

Dissolved oxygen (DO) 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.


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Methodology

A: Material, Reagent & Sample Preparation

Cement

Tap water

Alum (about 30g)

6 beakers (1L) and stirrer

B: Procedure-Turbidity vs. chemical dosage for turbidity removal

1. Prepare six 1-liter beakers of tab water and fill each beaker with 20g of cement. Make sure that

the same volume of water and cement is added to each beaker, and that the sample is of uniform

turbidity. Record the turbidity data. Label all the six beakers A-F.

2. Set beaker A as the control beaker.

3. Place the beakers on the stirrer, and stir the contents of beakers at the same speed.

4. Rapidly add varying doses of alum (2g to 10g) to each of beaker. Record the time. Stir for one

minute (Rapid mixing).

5. Compare the floc sizes and characteristics in the six beakers.

6. Stop the stirrer and observe the settling of floc particles. Compare the clarity of water in different

beakers.

7. Measure and record the turbidity of settled water in each beaker.

C: Procedure-Turbidity vs. dissolve oxygen level

1. Take 1-liter beaker of tap water as the control beaker. Measure the turbidity and dissolve oxygen.

Record the data.

2. Prepare 1-liter beaker of tap water and add 20g of cement.


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2. Stir it to homogenize the content. Measure the dissolve oxygen using DO meter. Then measure

the turbidity. Record the data.

3. Repeat steps 1 and 2 by adding the amount of cement in increasing 40g, 60g, 80g and 100g of the

sample analysis. Record the data.

4. Keep the turbid water for 1 day.

5. Re-measure the dissolve oxygen for each of the turbid water beaker as well as the control beaker.

Record the data.

Result & Discussion

1. Plot the graph and explain the relationship of turbidity and chemical dosage level?

2. Why turbidity will affect the dissolve oxygen level in the water?

3. Plot the graph and explain the relationship of turbidity and dissolve oxygen level?

4. Compare the results of dissolve oxygen for each of the turbid water beaker after 1 day with result

at No. 3. Any change? Discuss it.


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EXPERIMENT 4

Solids

Purpose:

To measure different type of solid content in the wastewater sample:

i. Total Solid (TS)ii. Total Dissolve Solid (TDS)iii. Total Suspended Solid (TSS)

Theory

The term solids is generally used when referring to any material suspended or dissolved in

wastewater that can be physically isolated either through filtration or through evaporation.Solids can be classified as either filterable or nonfilterable. Filterable solids may either be

settleable or nonsettleable. Solids can also be classified as organic or inorganic. The amount

of solids in wastewater is frequently used to describe the strength of the waste. The more

solids present in a particular wastewater, the stronger that wastewater will be. If the solids in

wastewater are mostly organic, the impact on a treatment plant is greater than if the solids are

mostly inorganic.

Total solids refer to matter suspended or dissolved in water or wastewater, and is related to

both specific conductance and turbidity. High concentrations of total solids can lower water

quality and cause water balance problems for individual organisms. On the other hand, low

concentrations may limit the growth of aquatic life. High concentrations of dissolved solids

can lead to laxative effects in drinking water and impart an unpleasant mineral taste to the

water. High concentrations of suspended solids also can reduce water clarity, contribute to a


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decrease in photosynthesis, bind with toxic compounds and heavy metals and lead to an

increase in water temperature through greater absorption of sunlight by surface waters.

Total volatile solids are those solids lost on ignition (heating to 500 degrees C.) They are

useful because they give a rough approximation of the amount of organic matter (biomass)

present in the water sample. Total fixed solids are the term applied to the residue of total

solids after heating to dryness for a specified time at a specified temperature.

Total Suspended Solids (TSS) is solids in water that can be trapped by a filter. TSS can

include a wide variety of material, such as silt, decaying plant and animal matter, industrial

wastes, and sewage. High concentrations of suspended solids can cause many problems for

stream health and aquatic life. High TSS can block light from reaching submergedvegetation. As the amount of light passing through the water is reduced, photosynthesis slows

down. Reduced rates of photosynthesis causes less dissolved oxygen to be released into the

water by plants. If light is completely blocked from bottom dwelling plants, the plants will

stop producing oxygen and will die. As the plants are decomposed, bacteria will use up even

more oxygen from the water. Low dissolved oxygen can lead to fish kills. High TSS can also

cause an increase in surface water temperature, because the suspended particles absorb heat

from sunlight. This can cause dissolved oxygen levels to fall even further (because warmer

waters can hold less dissolved oxygen, DO), and can harm aquatic life in many other ways.

High TSS can cause problems for industrial use, because the solids may clog or scour pipes

and machinery.

Volatile suspended solids are those solids lost on ignition (heating to 550C.) They are useful

to the treatment plant operator because they give a rough approximation of the amount of

organic matter (biomass) present in the solid fraction of wastewater, activated sludge and

industrial wastes.

Methodology

A: Material/Reagents/Apparatus:

100 ml cylinder

Pipette,

Deionized water

filter holder

Filter paper


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250 ml filter flask

Vacuum pump

Analytical balance

Desiccators

Aluminum dish.

Forceps for filter handling.

Oven.

Muffle furnace.

B: Procedure for measuring Total Solids (TS)

1. Shack the sample to mix it well.

2. Weigh an aluminum dish to nearest 0.1 mg (Weight of the empty dish is A).

3. Pipette 10 ml of the sample and add it to the aluminum dish.

4. Put the aluminum dish that contain the sample in an oven at 103-105 C, and let it for

about 1 hours to evaporate.

5. Take the dish out of the oven and allow it cool to room temperature in desiccators.

6.Weigh the dish to nearest 0.1 mg (Weight of the dish after evaporation is B).

Calculations:

Total solids (mg/l) = 1000 (BA)

10

C: Procedure for measuring Total Dissolved Solids (TDS)

1. Weigh an aluminum dish to the nearest 0.1 mg using an analytical balance (A).

2. Place a filter into the filter holder with the wrinkled surface up.

3. Place the filter holder assembly in the 250 ml filter flask, and wet the filter with deionized

water to ensure adhesion to the holder.

4. Transfer 50 ml of well mixed water sample to the filtering apparatus, while applying a

vacuum followed by 3 separate 10 ml washings of deionized water.

5. Slowly release the vacuum from the filtering flask and transfer 10 ml of filtrate (i.e. the

solution in the flask) to the pre-weighed aluminum dish (A).

6. Evaporate and dry the filtrate in an oven at 1802Cfor about 1 hours.

7. Take the dish out the oven and allow it to cool to room temperature in desiccators.


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8. Weigh the dish to the nearest 0.1 mg using an analytical balance (Weight of the dish after

evaporation is B).

Calculations:

Total dissolved solids (mg/l) = 1000 (BA)

10

D: Procedure for measuring Total Suspended Solids (TSS):

1. Weigh a filter (Weight of the filter before filtration is A).

2. Place the pre-weighed filter into the filter holder with the wrinkled surface up.

3. Place the filter holder assembly in the 250 mlfilter flask, and wet the filter with deionized

water to ensure adhesion to the holder.

4. Transfer 100 ml of well mixed water sample to the filtering apparatus, while applying a

vacuum, and follow that with 3 separate 10 ml washings of deionized water.

5. Dry the filter at the oven for 1 hour at 103-105 C.

6. Take the filter out the oven and allow it to cool to room temperature in desiccators.

7. Weigh the filter, after drying to the nearest 0.1 mg using an analytical balance (Weight of

the filter after drying is B).

Calculations:

Total Suspended Solids (mg/l) = 1000 (BA)

100

Results & Discussions

1. Discuss all the results that you obtain from the analysis of the solid content.

2. In wastewater treatment system, what can we do to reduce the content of the total suspended

solid? Justify your explanation by conducting a simple experiment and show the result of it.


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Reference

Standard Methods for the Examination of Water and Wastewater. (1992)

APHA-AWWA-WEF, 18th Edition.

Methods for Chemical Analysis of Water and Wastes. (1979) U.S. EPA 600/4-79-020.

Methods 160.1-160.5


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EXPERIMENT 5

Landfill: Leachate

Purpose

To study and monitor leachate from solid waste landfill by simulating rainfall.

To investigate is methane presence in the leachate by using UV-Vis Spectrometer.

Theory

The rapid growth in population and development has increased the amount of solid waste

generated. Methods used for the disposal of wastes in the country such as by open dumping or

controlled tipping tends to cause water pollution due to the production of landfill leachate. Landfill

leachate which is a liquid produced as a result of water percolation from the processes of water

infiltration, surface runoff, precipitation and liquid from the compacted waste not only would

pollute the ground water as it moves into the landfill but also the surface water. Once leachate

polluted the ground water it becomes a threat to the environment and would create potential

hazards to human health because it contains organic and inorganic substances as well as the toxic

heavy metal compounds. In other word improper management of disposal sites will cause water

pollution and pose short and long-term hazards and risk to the environment and the public.

Landfill leachate is a potentially polluting liquid, which unless returned to the environment in a

carefully controlled manner may cause harmful effects on the groundwater and surface water

surrounding a landfill site. For example, leachate from a biodegradable landfill will contain significant

concentrations of substances such as ammoniacal-nitrogen, which is toxic to many organisms or run-

off arising from a landfill containing only soil and rubble may contain suspended solids, be turbid,

and threaten fish and other aquatic organisms. The reasons for monitoring are to provide assurance

that the landfill operation does not cause harm to human health or the environment. The leachate

formation occurs when soluble components are dissolved (leached) out of a solid material by

percolating water. Leachate may also carry insoluble liquids (such as oils) and small particles in the


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form of suspended solids. Depending on the waste types, further contaminants may be introduced

as a result of biodegradation of wastes. Almost any material will produce leachate if water is allowed

to percolate through it. The quality of leachate is determined primarily by the composition and

solubility of the waste constituents.

Methodology

A: Material/Apparatus/Reagent

2 Cylinder columns (approximately 10L with 1 m height)

5 L of domestic waste

2 L of soil

B: Preparation of Fresh Leachate

1. Label the first column as A. Put in approximate 0.7m of soil. This column will be as control column.(See diagram)

2 Put in the waste/rubbish into the second column and label as B. Cover the rubbish/waste with a

layer of soil. Compact the waste and the soil. (See diagram)

3. 100mL tap water was sprayed on the head of the each of the columns homogeneously every 4

days to simulate raining.


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Results & Discussions

1. On the fifth day, collect leachate from the bottom of the columns.

2. Analysis the leachate that collected from column A and B for below parameters and explain your

results.

i. pH

ii. Temperature

iii. Biological Oxygen Demand (BOD5)

iv. Chemical Oxygen Demand (COD)

3. Measure the presence of methane for the leachate from column B. Is methane present? Explain

your results.


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Chemical Oxygen Demand*

Chemical Oxygen Demand (COD) is widely used to estimate the amount of chemically

oxydiseable matter in wastewater. It is measurement of the oxygen equivalent of the materials

present in the wastewater that are subject to oxidation by strong chemical oxidant (e.g.

dichromate). COD differs from BOD in that it measures the oxygen demand to digest all

organic content, not just that portion which could be consumed by biological processes.

COD is an important, rapidly measured variable for the approximate determination of the

organic matter content of water samples. Some water samples may contain substances that

are difficult to oxidise. In these cases, because of incomplete oxidation under the given test

methods, COD values may be a poor measure of the theoretical oxygen demand. It should

also be noted that the significance of the COD value depends on the composition of the water

studied.

The test is performed by adding the oxidizing solution of a dichromate salt (e.g. potassium

dichromate, K2Cr2O7) to a sample, boiling the mixture on a refluxing apparatus for two hours,

and then titrating the amount of dichromate remaining after the refluxing period. The titration

procedure involves adding ferrous ammonium sulphate (FAS), at a known normality, to

reduce the remaining dichromate. The amount of dichromate reduced during the test--the

initial amount minus the amount remaining at the end--is then expressed in terms of oxygen.

The test has nothing to do with oxygen initially present. It is a measure of the demand of a

solution or suspension for a strong oxidant. The oxidant will react with most organic

materials and certain inorganic materials under the conditions of the test. For example, Fe(II)

and Mn(II) will be oxidized to Fe(III) and Mn(IV), respectively, during the test.

Generally, the COD is larger than the BOD exerted over a five-day period (BOD 5), but there

are exceptions in which microbes of the BOD test can oxidize materials that the COD

reagents cannot. For a raw, domestic wastewater, the COD/BOD5 ratio is in the area of 1.5-

3.0/1.0. Higher ratios would indicate the presence of toxic, non- biodegradable or less readily

biodegradable materials.

The COD test is commonly used because it is a relatively short-term, precise test with few

interferences. However, the spent solutions generated by the test are hazardous. The liquids

are acidic, and contain chromium, silver, mercury, and perhaps other toxic materials in the


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sample tested. For this reason laboratories are doing fewer or smaller COD tests in which

smaller amounts of the same reagents are used.

Photometric Method

TestN Tube Reagent for COD,

Deionized water.

COD Reactor/Digester.

Colorimeter

Procedure

This exercise will involve the use of Hach reagents and the HACH COD reactor. The Hach instructions

will be followed in performing this experiment.

1. Homogenize 100 ml of sample for 30 seconds in a blender.

2. Turn on the COD Reactor. Preheat to 150 C. Place the plastic shield in front of the

reactor.

3. Remove the cap of COD Digestion Reagent Vial for the appropriate range:

Sample Conc. Range(mg/l) 0 to 40 0 to 150 0 to 1500 0 to 15000

COD Digestion Reagent Vial

Type

Ultra Low

Range

Low

Range

High

Range

High Range

Plus

4. Hold the vial at 45-degree angle. Pipette 2 ml (0.2 ml for the 0-1500 mg/l range) of sample

into the vial.

5. Replace the vial cap tightly. Rinse the outside of the COD vial with deionized water and

wipe the vial clean with towel paper.

6. Hold the vial by the cap and over a sink. Invert gently several times to mix the contents.

Place the vial in the preheated COD Reactor. Note that the vial will become very hot during

mixing.

7. Prepare a blank by repeating steps 3-6, substituting 2 ml deionized water for the sample.

8. Heat the vial for 2 hours.


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9. Turn the reactor off. Wait for about 20 minutes for the vials to cool to 120 C or less.

10. Invert each vial several times while still warm. Place the vials into a rack. Wait until the

vials have cooled to room temperature.

11. Note that if colour of the reacted sample is blue-green then repeat the test with a diluted

sample.

12. Switch On the spectrophotometer and select the program for COD test.

13. Clean outside of the vial that contain deionized water and put into the spectrophotometer.

Press zero.

14. Clean outside of the vial that contain sample. Put into the spectrophotometer and take

reading in mg/L.

Biochemical Oxygen Demand*

Theory

The BOD test is a bioassay in which the rate (and extent) of the aerobic degradation of organic

matter is assessed in terms of the amount of oxygen consumed during its degradation. The complex

reactions involved can be summarized as follows:

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. 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


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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 the

micro 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. The standard BOD

test takes 5 days to complete and is performed using a dissolved oxygen test kit. The BOD

level is determined by comparing the DO level of a water sample taken immediately with the

DO level of a water sample that has been incubated in a dark location for 5 days. The

difference between the two DO levels represents the amount of oxygen required for the

decomposition of any organic material in the sample and is a good approximation of the BOD

level.

Methodology

A: Reagents/Apparatus:

Scaled pipet

BOD bottles

BOD Nutrient Buffer

Nitrification inhibitor

Dissolved Oxygen (DO) probe

Incubator


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B: Procedure

1. Incubate at 20C, a series of BOD bottles containing given sample, diluted with aerated dilution

water which has been seeded with reconstituted Polyseed culture, for a series of daily time intervals

between 1 and 7 days, inclusive. Keep the water seals filled with water during incubation.

2. From the Table below, determine the sample size (ml) to be taken and diluted to

300 ml in standard BOD bottle.

Table 3.1: Sample size determination based of sample type

Sample Type Estimated BOD mg/l ml of sample

Strong Trade Waste 600 1

Raw and Settled Sewage

300

200

150

120

100

75

60

2

3

4

5

6

8

10

Oxidized Effluents

50

40

3020

10

12

15

2030

60

Polluted River Waters

6

4

2

100

200

300

3. Prepare a separate BOD bottle with dilution water only. This will be the dilution water blank.

5. If required, add 2 shots of nitrification inhibitor (approximately 0.16 g) to each bottle. This will

inhibit the oxidation of nitrogen compounds and the results will reflect only the carbonaceous

oxygen demand.

6. Fill each bottle with seeded or unseeded dilution water. When adding the water allow it to flow

slowly down the sides of the bottle to prevent bubbles from forming.

7. Stopper the bottle, being careful not to trap any air bubbles. Press on the stopper of the bottle

with your finger, and then invert several times to mix.

8. Determine the initial dissolved oxygen, DO (Dl).

9. Stopper the bottle again and add enough dilution water to the lip of the BOD bottle to make a

water seal.


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10. Place a plastic overcap over the lip of each bottle and place bottles in an incubator at 201C.

Incubate in the dark for 5days.

11. After 5 days, determine the DO content (mg/l DO remaining) in each bottle, using the DO probe

(D2).

Calculation

a. Calculate, the fraction (f)of sample found in each bottle using the equation shown below. Record

the value.

b. If the bottles were seeded, calculate thefvalue of each bottle using the equation shown

below. Record the value.

c. Calculate the BOD5 of each sample using the following formula. Record the value.

Where:

D1 = initial DO of sample, mg/L

D2 = final DO of sample, mg/L

B1 = initial DO of seed control, mg/L

B2 = final DO of seed control, mg/L

f= the value calculated in step b.

P = fraction of sample as calculated in step a.


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Experiment 6

Soil Pollution

Purpose

To determine the soil salinity.

Theory

Soil pollution comprises the pollution of soils with materials, mostly chemicals, which are out ofplace or are present at concentrations higher than normal which may have adverse effects on humans

or other organisms. It is difficult to define soil pollution exactly because different opinions exist on

how to characterize a pollutant, while some consider the use of pesticides acceptable if their effect

does not exceed the intended result, others do not consider any use of pesticides or even chemical

fertilizer acceptable. However, soil pollution is also caused by means other than the direct addition of

man-made chemicals such as agricultural runoff waters, industrial waste materials, acidic precipitates,

and radioactive fallout.

All soils contain water soluble salts. Plants absorb essential plant nutrient in the form of soluble salts,

but excessive accumulation of soluble salts, called soil salinity. Salinity is the concentration of

dissolved salts in water. High concentrations of neutral salts, such as sodium chloride and sodium

sulfate, may interfere with the absorption of water by plants through the development of a higher

osmotic pressure in the soil solution than in the plant cells. Salts may also interfere with the exchange

capacity of nutrient ions, thereby, resulting in nutrient deficiencies in plants.

Methodology

A: Material/Apparatus/Reagents

Filtration system

Conductivity meter

pH meter

Different type of soils (sandy soil, silty soil, clay soil)

Soils from different location (farm, backyard garden, industrial area)


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B :Procedure

1. Prepare 1:1 (soil:water) suspension.2. Filter the suspension using filtration system.3. Measure pH and conductivity of the filtrate.4. Perform step 1 to 3 for all the soil samples5. Records the data

Result and Discussions

1. Analysis the data for different type of soils from different location2. What is the conclusion you can made based on your analysis?3. Recommend on how to control salinity.

References

Ayers, R.S and Westcot, D.W. (1985) Water Quality for Agriculture Irrigation & Drainage paper No.

29. Food & Agriculture Organization of United Nation, Rome.

Env. Eng. Lab Manual

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Transcript of Env. Eng. Lab Manual