UNIVERSITY INSTITUTE OF TECHNOLOGY

RAJIV GANDHI PROUDYOGIKI VISWAVIDYALAYA, BHOPAL

ENVIRONMENT ENGINEERING-I

PRACTICAL FILE

SESSION 2014

SUBMITTED TO:- SUBMITTED BY:-

Prof. Amit Vishwakarma Palak Jain

0101CE111035

CONTENTS

1. Determination of ACIDITY in a water sample.

2. Determination of ALKALINITY in a water sample.

3. Determination of CHLORIDES in a water sample.

4. Determination of TURBIDITY in a water sample.

5. Determination of DISSOLVED OXYGEN (D.O.) in a given

waste water sample.

6. Determination of BIOLOGICAL OXYGEN DEMAND

(B.O.D.) in a given waste water sample.

ACIDITYOBJECT: To determine the acidity of given sample of water.

SAMPLE DETAILS:

Location:

Time:

Date:

Temperature:

APPARATUS: Burette , Pipette , Conical flask , Glazed tile.

REAGENTS:

a) 0.02 NaOH solution.b) Methyl orange Indicator solution , andc) Phenolphthalein indicator solution.

THEORY:

Acidity of a liquid is its capacity to donate H+ ions . It is also defined as the capacity of a solution to neutralize a std. alkali. The acidity of a water may be due to the presence of uncombined CO2 , mineral acids and salts of strong acids and weak bases. Since most of the natural waters and sewages are buffered by CO2 – bicarbonate system, the acidity present due to free CO2 has no significance from public health viewpoint.

PRINCIPLE :

Titrating or neutralizing samples at pH 4.3 can calc. the mineral acids present and contributing mineral acidity. The CO2 and bicarbonates (carbonic acids) present in the sample can be neutralized completely by continuing the titration to pH 8.3.

INTERFERNCE :

Colour , Turbidity , Iron , Aluminium , and residual chlorine are prime sources of interference.

PROCEDURE:

(A) Total Acidity This determination should be made on the spot on a fresh sample collected in a bottle and stoppered immediately to prevent escape of CO2 .

1) Measure suitable vol. of sample(50 or 100 mL) in 250 mL conical flask.

2) Add 2-3 drops phenolphthalein indicator and titrate with NaOH till faintpinkcolour appears indicating pH 8.3.

3) Note down the vol. of NaOH required as A.(B) Mineral Acidity

1) Measure suitable vol. of sample(50 or 100 mL) in250 mL conical flask.

2) Add 2-3 drops of methyl orange indicator and titrate with std. 0.02 NaOH till colour changes to faint orange characteristicof pH 4.4 -4.3.

3) Note down the vol. of NaOH required as B.

OBSERVATION:

CALCULATIONS:

RESULTS:

ALKALINITYOBJECT: To determine the alkalinity of given sample of water.

SAMPLE DETAILS:

Location:

Time:

Date:

Temperature:

APPRATUS: Burette,pipette,conical flask,glazed tiles

REAGENTS:

a)0.02N H2SO4 solution

b)methyl orange indicator solution and

c)phenolphthalein indicator solution

THEORY:

The alkalinity of water is measured by its capacity to neutralize acids. the alkalinity of natural water is due to presence of salts of carbonates, bicarbonates,silicates and phosphates along with hydroxyl ions in free state.however the major portion of alkalinity in natural water is caused by hydroxide, carbonates,bicarbonates which may be ranked in order of their association with high pH values.Alkalinity value provide guidance in proper doses of chemicals in water and waste water treatment process,particularly in coagulation,softening and operational control of anaerobic digestion.

PRINCIPLE:

Alkalinity of sample can be estimated by titrating with standard sulfuric acid.titration to pH 8.3 or decolourization of phenolphthalein indicator will show the complete neutralization of OH and ½ of CO3 while to pH of 4.5 or sharp change from yellow to orange of methyl orange will indicate total alkalinity

(complete neutralization of OH,HCO3,CO3)

INTERFERENCES:

Colour,turbidity,iron aluminium and residual chlorine are prime sources of interference.colour and turbidity can be avoided using potentiometric titration.residual chlorine can be removed by adding thiosulfate.

PROCEDURE:

a) Take 50 or 100 ml sample in a conical flask and 2-3 drops of phenolphthalein indicator.

b) If pink colour develops titrate it with 0.02N H2SO4 till the colour disappears or pH is 8.3.note the vol of H2SO4 required as A.

c) Add 2-3 drops of methyl orange tosame flask, and continue titration till pH comes down to 4.5.or yellow colour changes to orange.note tho vol. of H2SO4 as B.

d) If pink colour does not appear after addition of phenolphthalein continue as in c) above.

e) Calculate total or methyl orange alkalinity (T) or phenolphthalein alkalinity (P) and express it in mg/l as CaCO3.

OBSERVATIONS:

CALCULATIONS:

P- alkalinity as mg/l in CaCO3=A×1000

Vol of sample

T-alkalinity as mg/l in CaCO3=B×1000

Vol of sample

Where A=ml of H2SO4 required to bring pH to 8.3

B=ml of H2SO4 required to bring pH to4.5

N=normality of H2SO4 used.

Once the phenolphthalein and total alkalinities are determined then three types of alkalinities hydroxide,carbonate and bicarbonates can be easily calculated by following table-

Once carbonate and bicarbonate alkalinities are known then their conversion milligrams per litre CO3 of HCO3 are possible.

Mg/l CO3= mg/l carbonate alkalinity×0.6

Mg/l HCO3=mg/l bicarbonate alkalinity×1.22

RESULTS AND CONCLUSIONS:

CHLORIDES

OBJECT: To determine the amount of chlorides in the given sample of water.

SAMPLE DETAILSLocation:Time:Date:Temperature:

APPARATUS:Burette, Pipette, Conical flask, Glazed tile.

REAGENTS:a) Silver Nitrate(N/71),

b) Potassium chromate indicator, and

c) Chemicals for pH adjustment.

THEORY: chloride anion is generally present in natural waters in widely varying concentration. The presence of chloride in natural water can be attributed to dissolution of salt deposits, discharges of a effluents from chemical industries, oil well operations, Sewage discharges, irrigation drainage, contamination from refuge leachates, and sea water intrusion in coastal areas. Each of these sources result in local contamination of both surface water and ground water.

The salty taste produced by chlorides depends on the chemical composition of the water. A concentration of 250mg/l may be detectable in some water containing sodium ions. On the other hand , the typical salty taste may be absent in water containing 1000 mg/l chloride, when calcium and magnesium ions are predominant. A high chloride content also has deleterious effect on metallic pipes and structures as well as on agricultural plants. Three methods are suggested for the estimation of chloride, (1) Involving titration against standard mercuric nitrate solution.(2)An argeniometric method (Mohr’s method), and (3) A determination of chloride is required. Particularly at low concentrations the potentiometric method is suitable only when the sample is coloured or turbid, argeniometric is the simplest one and can

easily be carried out.

PRINCIPLE: Chloride is determined in a natural or slightly alkaline solution by titration with standard silver nitrate using potassium chromate as an indicator. Silver chloride is quantitatively precipitated before red silver chromate is formed.

INTERFERENCES: Bromide, iodide and cyanide are measured as equivalent of

chloride ions, hence pre-treatment of the sample with the help of special reagents must be done before titration to remove the interfering substances and colour and turbidity if present. If the sample contains sufficient thiosulphate, thiocyanate cyanide, sulphite and sulphide to interfere seriously with the determination, they may be oxidised to non-interfering substances as follows. Measure a suitable quantity of sample into a conical flask and dilute to 150 ml with water. Add 25 ml H2O2 (3%) and boil for 15 min, then add further 10 ml H2O2 and boil for 5 min .Repeat the same until the solution is thiocyanate free. If the sample is too coloured or turbid to allow the end point to be readily detected, this interference may be reduced by the following treatment with a suspension of aluminium hydroxide. Add 3ml aluminium hydroxide suspension to the measured quantity of sample. Stir thoroughly, set aside for a few minutes and filter. Wash the precipitate with distilled water. Collect the washing with the filtrate and continue as described under procedure.

PROCEDURE :1) Take 100 ml sample and adjust the pH between 7.0 and 8.0 2) Take 50 ml well mixed sample adjusted to pH between 7.0 and 8.0 and add 1.0 ml potassium chromate k2CRO4.3) Titrate with standard silver nitrate AGNO3 solution till silver chromate AG2CRO4 starts precipitating giving res colour. Note the final burette reading.4) Repeat the above the procedure for distilled water (50 ml) to establish reagent blank.

OBSERVATIONS:

Initial ph= …………………

RESULTS :

TURBIDITY

OBJECT: To determine the turbidity of a sample by nephlometer SAMPLE DETAILS:Location:Time:Date:Temperature:

APPARATUS: Turbidity of Nephlometer, Conical flask etc.

REAGENTS:Turbidity free water, stock turbidity suspension.

THEORY: Turbidity is a condition of water resulting from the presence of suspended matters and affects the light condition in the aquatic environment. The turbidity of natural water may be either due to suspended inorganic substance ,such as silt and clay or due to palnktonic organism .in fresh waters such as lakes and ponds the phytoplankton is sometimes sufficiently abundant to produce a notable reduction in light . Turbidity is an important limiting factor affecting productivity sample of lakes and ponds and varies greately with the nature of basin degree of exposure, nature of sediments, rains, floods and other factors There are various instrument for measurement of turbidity such as the Jackson’s turbid meter ,Hellige turbidmeter and nephlometer and hach turbid meter .Here we will describe the Nephlometer. The instrument operates on the principle that light passing through the sample is scattered by suspended particulate matter.A beam of light is passed through a cell containing the sample as the beam passes though the suspended particles an amount of light (directly proportional to turbidity) is scattered at right angles to the beam and is received by a photo multiplier and amplified .The readings are obtained in NTU (Nephlometer turbidity Unit).The digital Turbidmeter is very accurate and stable instrument for measurement of turbidity up to 1000 NTU (Nephlo Turbidity unit)

PRINCIPLE :The method is based on the comparison of the intensity of light scattered by the sample under defined condition with the intensity of light scattered by a standard reference suspension under the same condition .The higher the scattered light ,the higher the turbidity.

PROCEDURE:1. Allow sufficient warm up period after switching ON the instrument.2. Take the test tube containing distilled water or blank solution in the test

tube holder and close the test tube holder cover .make sure that the mark on test tube coincides with the mark on the panel.

3. Select the required range for measurement.4. Adjust the display to 000 by adjusting ‘set Zero’ knob.5. Remove the test tube containing distilled water and fill another test tube

containing standard solution say 400 NTU as per the expected range of unknown solution .place it in the tube holder .

6. Take the measurement of the solution suspension and adjust the ‘calibrate ‘knob so that the display reads the selected standard solution value.

7. Again check the display zero with the tube containing distilled water.8. Now the instrument is ready to take measurement of any unknown

suspension.

RESULT & CONCLUSION:

DISSOLVED OXYGENObject: - To determine the dissolved oxygen in the given sample of water.

Sample Details:

Location:

Time:

Date:

Temperature:

Apparatus: 300ml ground glass, stoppered bottles, sampling device for collection of samples, Nessler’s tube, tubes, burette, pipette, conical flask, glazed tile etc.

Reagents: MnSO4 solution, Conc. H2SO4, Alkali Iodide Azide sol., N/40 Na2S2O3 sol., starch indicator

Theory: All living organisms are dependent upon oxygen in one form or the other to maintain the metabolic process that produce energy for growth and reproduction. Aerobic processes are the subjects of great interest for their need of free oxygen. Dissolved oxygen ( DO ) is also important in precipitation and dissolution of inorganic substances in water.

The solubility of atmospheric oxygen in fresh water ranges from 14.6 mg/L at 0 deg.C to about 7.0 mg/L at 35 deg.C under one atmospheric pressure. Since it is a poorly soluble gas its solubility directly varies with the atmospheric pressure at any given temperature.

The water sample is collected under the surface and allowed to flow in to the sample bottle slowly to prevent mixing in air. Glass stoppered bottles are best because the stoppers prevent mixing with air.

Analysis of DO is a key test in sanitary engineering practice. The following illustrations reveal the importance of DO as a parameter:

1. It is necessary to know DO levels to assess quality of raw water and to keep a check on stream pollution.

2. In liquid watste dissolved oxugen is the factor that determines whether the biological changes are brought out by aerobic organisms.

3. DO test is the basic of BOD test, which is na important parameter to evaluate pollution potentioal of waste.

4. DO is necessary for all aerobic biological treatment processes.5. Oxygen is an important factor in corrosion. DO test is used to control

amount of oxygen in boiler feed waters.6. Do is necessary for all aerobic biological wastewater treatment processes.

Principle:

1. THE WINKLER METHOD WITH AZIDE MODIFICATION

Oxygen present in sample rapidly oxidizes the dispersed divalent manganous hydroxide to its higher valency, which precipitates as a brown hydrated oxide after addition of NaOH and KI. Upon addification, manganese reverts to divalent state and liberates iodine from KI equivalent to the original DO content. The liberated iodine is titrated against Na2S2O3(N/80) using starch as an indicator.

INFERENCE

Ferrous ion, ferric ion, nitrite, microbial mass and high-suspended solids constitute the main sources of interference. Modifications in the estimation procedure to reduce these interferences, Modifications in the estimation procedure to reduce these interferences are describes in the procedure,

CHEMICAL REACTIONS

Winlker’s Method

1. MnSO4 + 2KOH = Mn(OH)2 + K2 SO4

(White ppt.)

2. 2Mn(OH)2 + O2 = 2MnO(OH)2

(D.O.) (Brown ppt.)3. MnO(OH)2 + 2H2SO4 = Mn(SO4)2 +3H204. Mn(SO4)2 + 2KI = MnSO4 + K2 SO4 + I2

5. 2Na2S2O3 + I2 = 2NaI + Na2SO4O6

Wrinkler’s Method with Azide Modification

1. 2NaN3 + 2 H2SO4 = Na2SO4 + 2HN3

(Sodium Azide)2. 2NaNO2 + H2SO4 = 2HNO2 + Na2SO4

3. NH3 + HNO2 = N2O + N2 +H2O

Procedure:

1. To 300ml shape in BOD bottle, add 2ml Mangnese sulphate solution.2. Then add 2ml alkali iodide azide solution.3. Insert the stopper and mix by inverting the bottle 15 times. Precipitate is

allowed to settle leaving a clear supernatant solution.4. Add 2ml conc, sulphuric acid. Insert the stopper and shake well.5. From the bottle, 203ml of content is taken out.(this is because 200ml of the

original sampe must be used for titration. As 2ml of eah manganese sulphate and alkali iodide azide reagents have been addd, the proper quantity corresponds to 200ml

6. i.e. 200 * 600 = 203 ml7. (300-4)8. 1-2 ml of starch solution is addwd which turns its colour to blue.9. Titrate again till the blue colour just disappears and note the corresponding

reading.

Observation :

Initial pH .

S.No.

Volume of Sample

Initial Burette Reading

Final Burette Reading

Net.Vol. of Thiosulphate Required A

1.2.3.

Calculations :

1 ml of 0.0025 N Na2S2O3 = 0.2 mg of O2

(.2 * 1000) ml of Thiosulphate (A)

DO in mg/l = .

200

Results and Conclusion :

Modification of DO estimation procedure

a. Alsterberg azide modification:

This method outlines earlier is known as azide modification of Winkle’s method and also as Alsterberg azide modification. The reagent NaOH + KI +NaN3 is used in the method to eliminate caused by NO2. This also reduces interference due to higher concentration of ferric iron.

BIOCHEMICAL OXYGEN DEMAND

OBJECT: to determine the biochemical oxygen demand of the given sample of water (B.O.D.)

SAMPLE DETAILS:

Location:

Time:

Date:

Temperature:

APPARATUS:

300ml ground glass stoppered bottles, sampling device for collection of samples, incubator, burette, pipette, conical flask, glazed tile etc.

REAGENTS:

MnSO4, conc. H2SO4, alkali iodide azide solution, N/40 N2S2O3 Solution, starch indicator FeCl3, CaCl2, Na2SO3, phosphate buffer.

THEORY:

Biochemical oxygen demand (B.O.D.) is defined as the amount of oxygen required by microorganisms to stabilise biologically decomposable organic matter in a waste under aerobic conditions. The BOD test is widely used to determine (1) the polluted load of waste waters, (2) the degree of pollution in lakes and streams at any time and their self purification capacity, (3) efficiency of waste water treatment methods.

Since this test is mainly a bio- assay procedure involving the measurement of O2

consumed by bacteria while stabilizing organic matter under aerobic conditions, it is necessary to provide standard conditions of nutrient supply, pH, absence of nutrient growth inhibiting substances and temperature. Because of the low solubility of O2 in water, strong wastes are always diluted to ensure that the demand doesn’t increase the available oxygen. a mixed group of organisms should be present in the sample, if not, the sample has to be seeded artificially. Temperature is controlled at 200C. the test is conducted for 5 days as 70 to 80 % of waste is oxidised during this oxidised during this period.

INTERFERENCES:

Since DO estimation is the basis of BOD test, sources of interferences in the BOD test are same as that in DO test. In addition, lack of nutrients in dilution water, lack of an acclimated seed organism, presence of heavy metals and other toxic materials like residual chlorine are the sources of interferences in this test.

Seed organisms and presence of heavy metal or other toxic material such as residual chlorine and other sources of interference in this test.

PROCEDURE:

A)Preparation Of Diluted Water1. Acetate the required volume of distilled water in a container by bubbling

compressed air for 1-2 days to attain DO saturation. Try to maintain the temperature near 20⁰C

2. Add 1 ml each of phosphate buffer, magnesium sulphite, and Calcium chloride & ferric chloride solution for each litre of dilution water. Mix well.

3. In the each case of wastes which are not expected to have sufficient bacteria population add seed to the dilution water. Generally settled sewage is considered sufficient for 1000 ml of dilution water

B)Dilution of sample:1. Neutralize the sample to pH around 7.0 if it is highly alkaline or acidic.2. The sample should be free from residual chlorine. If it contains residual

chlorine remove it by using Na2SO3 solution as follows. Take 50 ml of the sample and acidity with addition of 10 ml & 1 ml acetic acid. Add about 1 g KI. Titrate with sodium sulphite (0.025 N) using starch indicator. Calculate the volume of sodium sulphite required per ml of the sample and add accordingly to the sample to be tasted for BOD.

3. Samples having high DO content i.e., DO 9 mg/l due to either algal growth or some other reason, reduce the DO content by aerating and agitating the samples.

4. Make several dilution of the pre-treated sample so as to obtain about 50% depletion od Do in dilution water but not less than 2mg and the residual oxygen after 5 days of incubation should not be less than 1mg/l. prepare dilution as follows:

5. Siphon out seeded dilution water in a measuring cylinder or volume flask half the required volume. Add the required of carefully mixed sample. Dilute to the desired volume by siphoning dilution water and mix well.

The following dilution are suggested:

1. 0.1% to 1% ………….. Strong trade waste2. 1.0% to 5% ………….. Raw or settled sewage3. 5.0% to 25% …………… Treated effluent4. 25% to 100% …………… Raw or settled sewage

6. Siphon the dilution prepared as in 4 in three labelled bottles and stopper immediately

7. Keep 1 bottle for determination of the intial DO and incubate 2 bottles at 20⁰C for 5 days. See that the bottles have a water seal.

8. Prepare a blank in duplicate by siphoning plain dilution water to measure the O2 consumption in dilution water.

9. Fix DO of the bottles kept for immediate DO determination and blank by adding 2 ml MnSO4 followed by 2 ml alkali-azide as described in the estimation od DO.

10. Determine DO in the sample and in the blank on initial and after 5 days.

S. No. N/40 Sodium Thiosulphate

D.O. in ppm=

O2

consumed=

Initial Burette Reading

Final Burette Reading

Volume Consumed

Volume Consumed

D.O. of blankD.O. diluted sample

Blank% Diluted waste water sample

CALCULATION:

Let D0 = DO in sample bottle on 0⁰C day

D1 = DO in the sample bottle on 5⁰C day

C0 = DO in the blank bottle on 0th day

C1 = DO in the blank bottle on 5th day

C0-C1 = DO depletion in the dilution water alone

D0-D1 = DO depletion in the sample + dilution water

(D0-D1)- (C0-C1) = DO depletion to micros

RESULTS :