OPERATIONS AT THE WASTE WATER LABORATORY

ENVIRONMENTAL CHEMISTRY DIVISIONC.S.I.R.-WATER RESEARCH INSTITUTE

INDUSTRIAL ATTACHMENT REPORTSubmitted to

UNIVERSITY FOR DEVELOPMENT STUDIESFaculty of applied sciences

Department of applied chemistry and biochemistry

BYGANOO RAPHAEL KWAKU (FAS/3986/10)

In partial fulfillment of the award of B.Sc applied chemistry

26 TH MAY-31 ST JULY 2013

TABLE OF CONTENTS

Abstract………………………………………. i

Introduction…………………………………... ii

Acknowledgements…………………………..iii

Main text (laboratory analyses)………………iv

Conclusion …………………………………....v

Recommendations …………………………...vi

References ……………………………………vii Appendix ……………………………………...viii

i

ABSTRACT

Water covers 2/3 of the world surface, and its important in human daily usage therefore it important to check the quality of water and waste water because they end up in our major water bodies and influence aquatic life and the resultant food chain.This report takes a preview of the laboratory procedures and analytical methods like TS,TDS,TSS oil and grease tests used in evaluating solids and other parameters like nutrients associated with water quality.

ii

INTRODUCTION

Industrial attachment forms part of the Third Trimester Field Practical Program(TTFPP) of the curriculum of the university for development studies(UDS).The incorporation of industrial attachment into the TTFPP curriculum places the products of UDS above their colleagues in other tertiary institutions on the job market due to the experience and resilience inculcated in them through rigorous academic exercise.

In partial fulfillment of the award of B.Sc applied chemistry,I undertook 10 weeks industrial attachment at C.S.I.R-Water Research Institute,Accra.

The Council for Scientific and Industrial Research (CSIR) is a Governmental institution which undertakes scientific research and comes out with suitable solutions to the problems we face scientifically as a nation. they also develop new ideas and scientific innovations to improve science and technology in the Ghana.

CSIR has 13 research institutes of which water research institute is a member institute.it was from in 1996 as a merger of institute of aquatic biology(AIB) and water resources research institute(WRRI).

This institute generates and provides scientific information, strategies and services towards the national development, utilization and management of the water resources of Ghana in support of the socio-economic advancement of the country, giving special attention to the agriculture, health, industry, energy, transportation, education and tourism sectors.

Basically, this institute carries out research into water for both government and private bodies.

The Water Research Institute (WRI) has 5 divisions namely; the Environmental Chemistry Division (ECD), environmental health and biology(EH&B),groundwater division,surface water division and Fishery division.

iii

ACKNOWLEDGEMENTS

I wish to express my appreciation to the administration of water research institute for the industrial opportunity given me, also my thanks goes to the entire staff of the Environmental Chemistry Division for the cordial and peaceful environment provided which made my stay successful. Special thanks goes to Dr. Osmund Ansa Asare HOD of ECD, Dr. Isaac O.A. Hodgson dep. Director of WRI and Mr Adu Ofori for the fatherly love, encouragement and mentorship given me. Further thanks goes to my supervisors in the persons of Mr Daniel Amoah and Mr Christopher Yom Nfojoh.

Lastly,I wish to thank miss Grace Baffour(NSS personnel),my co-interns namely;Isaac Yartey(T-poly),Apafo Esther(KNUST),Agboyibor Clement(UCC),Sani Mohammed,Heheatror Selorm Antonio and Akpalu Johannes(UDS).

iv

LABORATORY ANALYSES

I was assigned to the waste water laboratory section of ECD.this division carries out water quality on waste water , effluents and domestic waste samples.

Physical and chemical methods are used to examine these waste water samples. Various parameters are done to assess the quality of waste water released into major water bodies. Most of the samples analyzed in this lab are collected from companies and individuals.

The various tests that are conducted includes; pH, Conductivity, Turbidity, Suspended solids, BOD, COD, Oil and Grease,alkalinity and chloride test.

All laboratory analyses are preceded by field sampling. I had the opportunity of sampling at Kasapreko Ltd, Pioneer food cannery(PFC),the Movenpick ambassador hotel,Cadbury Ltd,Phytoriker pharmaceuticals Ltd, Cocoa processing company Ltd, Accra brewery Ltd(ABL),Nima creek and the Korle lagoon.

Samples are stored in 1L polyethylene containers and analyses carried on the day of sampling. samples are stored in refrigerators below 4 degree celcuis and warmed to room temperature if analyses cannot be carried out on the day of sampling. Some physical parameters like pH, conductivity and temperature are tested for at the sampling field because the composition of the sample may change before it arrives in the laboratory due to the growth of organism as a result of anaerobic conditions created in the containers.growth can be controlled by storing the sample in the dark place and at a low temperature until it can be analyzed.

TOTAL SOLIDS (TS)

Total solids refers to particulate matter in a water sample.it is the sum total of total dissolved solids(TDS) and total suspended solids(TSS).and settle able solids in water. They occur in water sample as a result of human ativities and or natural phenomenon like silting.

1

It is important to check the level of total solids in wastewater because solids contributes to the turbidity of receiving waters,turbidity interferes with the photosynthetic activity of phytoplanktons which are at the base of the food chain and also,solids blocks the gills of fishes restricting respiratory activity of the gills.

PRINCIPLE

A known volume of a well mixed sample is transferred into a weighed clean dish and evaporated on a water bath,dried at a constant temperature of 105 degree celcuis in an oven,and dried again in the dessicator. The increase in weight over that of the empty dish represents the total solid.

DETERMINATION

1.Weighed a clean evaporating dish that was previously washed,dried in an oven at 105 degrees celcuis,and stored in the dessicator.2. shake the sample vigorously and immediately transfer a measured volume into the pre-weighed evaporating dish using a graduated cylinder.3. Evaporate sample on a steam or water bath 4.dry evaporated sample for 1 hour in an oven at 105 ºC.5. dry the dishes containing the samples in a desiccator and weigh cooled dish as secont weight.

CALCULATION

Total Solid (mg/l) = (A-B) x 10 6 CWhere A = Weight of dried residue + dish (g) B = Weight of dish alone (g) C = Volume of sample (ml)

Results are expresses as Total Solids dried at 105 ºC in mg/ L to the nearest mg/ L of sample

2

CHEMICAL OXYGEN DEMAND (C.O.D.)

It is defined as the oxygen equivalent of organic matter content. It represents the total pollution load of most waste water discharges. Its purpose is to measure the liquid organic substances in a standard. It’s also a parameter used in the study of bioreactor.PRINCIPLE

Organic matter is normally oxidized by boiling mixture of chromic and sulphric acids. The sample is refluxed and after digestion the remaining unreacted dichromate is titrated with ferrous ammonium sulphate to determine the amount of dichromate consumed and calculated in terms of oxygen equivalent.

DETERMINATION 1.Place 5ml of the sample into a test tube 2.add 3ml ofpotassium dichromate and 7ml of sulphric acid to the sample in the test tube.3.Tightly cap test tube, shake to mix completely.4.place the test tubes in a digestor and digest at 150ºC for 2 hours. 5.Cool samples to room temperature and add 2 drops of ferroin indicator after digestion. 6.Titrate the samples against Standard Ferric ammonium Sulphate (FAS) solution. The color change is from blue-green-reddish brown or wine.7. In the same manner reflux and titrate the blank containing the reagents and a volume of deionised water equal to that of the sample.

CALCULATION

COD as mg O2/L = (A-B) x M x 8000 ml sampleWhere A = ml FAS used for blank B = ml FAS used for sample M= molarlity of FAS used 8000= milliequivalent of oxygen x 1000 ml/l

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OIL AND GREASE

Oil and grease contains a wide array of hydrocarbon compounds. They can be defined as any material recovered as a substance soluble in the solvent.Oil and grease in waste samples being discharged into receiving waters reduces the surface tension of those water thereby affecting aquatic life.

PRINCIPLE

Emulsified oil and grease is extracted from water by intimate contact with trichlorotrifluoroethane/petroleum ether.

DETERMINATION

1.A known volume of the sample is taken and acidified with HCl and transferred to a separation funnel.2. 30ml Trichlorotrifluoroethane/petroleum ether is carefully used to rinse the sampling bottle. Cork separation funnel and shake vigorously.3.Release pressure from bottle, open and hung separation funnel upright to allow solvent to separate. 4.Drain solvent layer through a funnel containing solvent moistened filter paper and cotton wool into a clean-tured evaporating dish when the layer separates. Extract twice and combine extracts in a tured flask.5.evaporate solvent from evaporation dish on a water bath at 70ºc till the dish is dry. 6.dry dish in an oven at 105 degrees celcuis and further dry dish in a dessicator. 7.after 30min, weigh the dish.

CALCULATION

Mg oil and grease/L = (A-B) x 1000 x 1000 ml sampleWhere A = total gain in the weight of the flask in grams B = solvent blank

4

DISSOLVED OXYGEN

It is an indication of the organic content of water bodies’ .higher D.O. values indicate the presence of less microbial activities in the sample and the lower D.O indicates more microbial activities.Dissolved oxygen levels in natural and waste water depend on the physical, chemical and biological activities in the water body. The analysis for D.O. is a key test in water pollution and waste water treatment process control.

PRINCIPLE

It is based on the addition of divalent manganese solution followed by strong alkaline to the sample in a glass stoppered bottle. D.O. rapidly oxidizes an equivalent amount of the dispersed divalent manganous hydroxide precipitate to hydroxide of higher states. In the presence of iodine ions in an acidic solution, the oxidized manganese reverts to a divalent state with the liberation of iodine equivalent to the original D.O content. The iodine is then titrated with a standard solution of thiosulphate. The end point value gives an indication of the level of microbial activity.

DETERMINATION

1.To the sample collected in a 250-300ml D.O. bottle add 2.0 ml of Winkler 1 (manganous Sulphate) solution followed by 2.0 ml of Winkler 2 (alkali –Iodide Azide). 2.mix by inverting the bottle several times, and allow precipitate (ppt) to settle for a few minutes.3. Add 2.0 ml of concentrated H2SO4 and then shake well to mix until all precipitate dissolves. 4.Pour 100 ml of the sample an erlenmayer flask and titrate against standard sodium thiosulphate solution until a pale yellow colour is observed. Using starch as an indicator, further titrate until blue colour changes to colourless.

CALCULATION

For titration of 100ml sample;1 ml 0.0125 M Na2S2O3 = 1.0 mg D.O./ LTherefore X ml 0.0125 M Na2S2O3 = X mg D.O./LWhere X is the titre

5

TOTAL DISSOLVED SOLIDS (TDS)

Total dissolve solid is the amount of solids that is able to filter through a glass fibre filter of 2.0 micrometers. The micro –glass fibre filter paper is of very small pore size. This method is suitable for the determination of surface water, groundwater, saline water and waste water. Total dissolve solids may affect water quality by contributing to the turbidity levels.

PRINCIPLE

The sample is filtered and a known volume of the filtrate is evaporated on a water bath. The residue left after evaporation is dried at a constant temperature of 105 ˚C for waste water and 180 ˚C for portable water in an oven. The increase in weight over that of the empty dish is the weight of the total dissolved solids.

DETERMINATION

1.Prepare a glass fiber disc by placing the disc on a filter holder and conditioning it with three successive 20 ml volume of distilled water. Vacuum is applied to ensure all traces of water have passed. 2.The evaporating dishes are also prepared by heating a clean dish at 105 ˚C for waste water and 180 ˚C for portable water for one hour in an oven. The heated dishes are cooled and stored in a dessicator but are weighed just before use.3.The sample is vigorously shaken and filtered using the filtration apparatus. The filtrate is then filtered through the micro glass fibre filter paper in vacuum until much water is removed. The sample is then washed with successive 10 ml volume of deionised water, and then filtered for a few minutes. 4.a known volume of the total filtrate is then transferred to the already weighed evaporating dish and evaporated to dryness on a water bath.5.The evaporated sample is then dried in an oven at 105 ˚C for waste water and 180 ˚C for portable water for one hour.The dish is cooled in a dessicator after which it is re-weighed.

CALCULATION

T.D.S (mg/L) = (A-B) x 10 6 C

Where; A = weight of dried residue and dish /g B = weight of empty clean dry dish /g C = volume of sample used /ml Results are expressed as T.D.S. dried at (temperature used) ˚C, mg/L to the nearest 0.1 mg/L

TOTAL HARDNESS

Total hardness is defined as the sum of calcium and magnesium concentrations both expressed as calcium carbonate mg/L. Depending on the source and treatment to which the water has been subjected to, the hardness range from 0 -100 mg/ L. It is applied to potable water, waste water, soil extract saline water.

PRINCIPLE

EDTA (Ethylenediaminetetraacetic acid) and its sodium salt form a chelated Y-soluble complex when added to a solution of certain metal cations. If small amounts of dye such as Eriochrome Black T is added to an aqueous solution containing calcium and magnesium ions at a pH of 10 + 1, the solution will become wine red. If EDTA is added as a titrant the calcium and magnesium will be compressed .After sufficient EDTA has been added to compress all magnesium and calcium the solution will turn from wine red to sea blue which is the end point of the titration.

DETERMINATION

1.Pipette 50.0 ml of the sample or an aliquot made up to 50.0ml in a conical flask.2. Add 1ml of NH4Cl buffer solution to engineer the pH to 10 + 1.3. Add a few crystals (0.1-0.2 g) of Eriochrome Black T indicator.4.Mix constantly and titrate with standard 0.01 EDTA until the last trace of purple disappear or colour turns bright blue.

CALCULATION

Total hardness = ml EDTA x B x 1000 ml sample

Where B = ml CaCO3 equivalent to 1 ml EDTA titrant i.e. ml CaCO3

ml EDTAResults are expressed as mg/ L CaCO3 to 3 significant figures.

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BIOCHEMICAL OXYGEN DEMAND (BOD)

Biochemical oxygen demand is the amount of oxygen required for the microbial decomposition of organic material in a water sample. The biochemical oxygen demand test measures the amount of molecular oxygen utilized by micro organisms to degrade organic material during a specified incubation period. The BOD is roughly proportional to the amount of biodegradable organic material in the test sample. Thus a higher BOD value indicates more biodegradable organic material which shows that larger amount of oxygen has been depleted during the decomposition of organic material. This method is applicable to fresh water, waste water and saline water.

PRINCIPLEAn air tight bottle of specified size is filled with prepared diluted sample till it overflows and it is incubated for five days at a temperature of 20 ºC. The dissolved oxygen is measured before and after the incubation period. The BOD is calculated from the difference in the initial and final dissolved oxygen.

DETERMINATION

1.add 6ml of phosphate buffer,6ml of manganous sulphate,6ml of ferric chloride and 6ml of calcium chloride nutrients to 6L of aerated tapwater and mix by inverting the container.2.based on the measured conductivity,take a known volume of sample into a 600ml graduated measuring cylinder and use the aerated tapwater to dilute to the mark.3.fill the BOD bottle with the diluted sample until it overflows.4.add 2 ml of MnSO4 (Winkler 1) followed by 2 ml alkaline-iodide azide (Winkler 2) and cork tightly to exclude air bubble. Shake thoroughly by inverting several times and allow precipitate to settle.5. Add a 2 ml concentrated H2SO4, cork and invert several times for the precipitate to dissolve to a yellow colour.

6. Take 100 ml of the sample and titrate against Sodium thiosulphate to a pale yellow colour and add 2ml of starch as indicator.continued the titration by adding the titrant drop-wise until a blue colour changes to colourless.

CALCULATION

BOD5, mg/l = (D1-D2) x nWhere n = dilution factorD1 = DO of diluted sample immediately after preparation, mg/ LD2 = DO of diluted sample after 5 days of incubation at 20 oC mg/ L

Express result as BOD5 in to the nearest whole number.

SUSPENDED SOLIDS BY GALVANOMETRIC METHOD

Solids (S.S.) are the solids retained in a filter of 2.0 µm (or smaller) poresize under specific conditions. This analytical procedure describes the method for the determination of suspended solids that involves filtration and drying at 105 oC.The method is suitable for the determination of surface water, ground water, saline water and waste water.

PRINCIPLEA well mixed sample is filtered through a weighed standard glass-fibre. The residue retained is dried to constant weight at 105 oC. The increase in weight of the filter paper represents the total suspended solids.

DETERMINATION

1. Prepare the glass fibre disc by placing the disc on the membrane filter holder.Wash the disc with three successive 20 ml volume of the distilled water and then apply vacuum till all traces of water are removed. Remove filter from filtration apparatus and transfer to a dish as support. Dry in an oven at 105 o C for an hour.store in the dessicator until needed.but weigh immediately before use.2.Shake the sample bottle and rapidly transfer a suitable volume to yield not more than 200 mg residue to the funnel of the suction. Apply vacuum till all traces of water are removed.

93. Remove the filter paper and place in the dish. Dry in an oven at 105 o C for one hour. Cool in a dessicator and re-weigh.

CALCULATION

Total Suspended Solids mg/ L = (A-B) x 10 6 C

Where; A is the weight of filter paper + empty dried dish /g. B is the weight of filter paper with residue + empty dried dish /g. C is the volume of the sample used.

Results are expressed as Total Suspended Solids dried at 105 o C, mg/ L

SOME COMMON PARAMETERS CARRIED OUT IN THE LAB:

PH - PH METER AND COMBINATION ELECTRODE METHOD.

pH indicates the intensity of the acidity or basicity levels of a solution. This analytical procedure describes the method for the determination of pH using a pH meter and combination electrode.

PrinciplepH is measured with a pH meter and a combination electrode. The electrode is first calibrated against pH buffer 7 and 4 or 9 to adjust the response of the glass electrode. The electrode is then immersed in the test solution where a change in potentials in the glass electrode compared with reference electrode (that is at constant potentials) is measured. The potential is converted into pH units by the top of the glass electrode that is sensitive to pH change. During sampling, it is important to be measured in situ because of possibility of exchange of dissolved gases such as carbon dioxide or oxygen may affect readings.

Determination

- Connect the electrode to the meter and calibrate the system using pH 4 and 7 buffers.Bring the buffer solutions to same temperature compensation control to this value.

10- Rinse and fill a beaker with pH 7 buffer. Immerse the electrode and

stir gently once or twice. Cease stirring and with the electrode suspended in the solution (clear off the sides of the beaker), wait

for 1-2 minutes for a stable reading to be obtained. Adjust to the exact pH value appropriate to the buffer in use.- Withdraw and rinse the electrode with deionized water and shake

gently to remove water.- Rinse the electrode with deionized water. Measure your sample

and record the pH value. The results are read to the nearest 0.01 pH units and it is measured in millivolts.

CONDUCTIVITY – CONDUCTIVITY METER METHOD

This can be defined as the ability of a substance to conduct electric current. It is

the ions present in the substance that conduct the electricity and this gives an

estimation of the number of ions present in the sample.

PrincipleAt constant temperature, the electrical conductivity of a given water sample is a function of its concentration of ions. The probe is sensitive to the ionic change in the solution, a factor that controls the current carrying capacity of the water sample. The conductivity meter provides a direct read-out of the conductivity of the test solution. This is then corrected to the standard temperature of 25oC.

Determination

(a) Using cyberscan PC 510 Conductivity meter.- Rinse the conductivity cell and the beaker or vessel thoroughly

with a portion of the sample to be examined.- Then fill the beaker completely.- Insert the cell into the beaker; for meters with temperature

compensation, when water sample and the equipment have reached the same temperature, read the indicated value (conductivity) on the meter.

11(b) Using field conductivity meter, follow the above steps and then,

- Take temperature of the sample.- Adjust the temperature control on the meter to the sample

temperature.

- Insert the probe into the vessel and read the conductivity.

Calculations

For the conductivity meters without automatic temperature compensation, conductivity at 25oC is given by

K = (Km) C 1+0.019(t-25)Where:Km = measured conductivity, μm/cm at 25oC C = cell constant, cm t = Temperature

ALKALINITY

It is water’s acid neutralizing capacity. Contributors to water include CO3, H2CO3, OH; an indication of the concentration of these constituents. The total alkalinity is the equivalent amount of strong acid needed to neutralize the ions. It is useful in establishing the amount of chemical required for the treatment of water.

PrincipleHydroxyl ions present in a sample as a result of dissociation or hydrolysis of solute reacts with additions of standard acid. Alkalinity thus depends on endpoint pH used. Titration to the endpoint of pH 8.3 determined the phenolphthalein alkalinity (P). Titration to the endpoint of pH 4.5 gives the total methyl orange alkalinity (T). For most purposes the point of pH 4.5 indicated by methyl orange gives sufficiently accurate results. Alkalinity is used in the interpretation and control of water and waste water treatment processes.

Method Method used depends on the pH. If pH is >8.3, back titration is done by:- Add phenolphthalein to the sample; colour changes to pink- Titrate against standard HCl till the colour disappears to colourless.- Methyl orange is added and titrated against the acid till the methyl orange

endpoint.- The total alkalinity is the total of the phenolphthalein and the methyl orange

endpoints.

12If pH is < 8.3, titration is carried out straight away with the addition of methyl orange.

CalculationPhenolphthalein alkalinity as CaCO3 (P) = 50,000 x A x Nmg/L

VTotal Alkalinity as CaCO3 (T) =50,000 x B x Nmg/L

VWhere A=ml of standard acid solution added to obtain the phenolphthalein endpoint of 8.3pH

B= ml of standard acid solution added to obtain the methyl orange endpoint of 4.5 pH

N= normality of acidV= volume of sample used

TURBIDITY – NEPHELOMETRIC METHOD

Caused by the presence of suspended matter, such as clay, silt, finely divided organic and inorganic matter, plankton and other microscopic organisms. It is an expression of the optical properties of a solution which causes light to be scattered. The range of determination is 0.1 – 1000NTU; where NTU means Nephelometric Turbidity Units.

Principle The method is based on comparison of intensity of light scattered by the sample under defined conditions with the intensity of light scattered by a standard reference suspended under the conditions. The higher intensity of scattered light, the higher the turbidity.

Determination - Shake sample vigorously and pour into sample cell to at least 2/3 full.- Select the appropriate range with the range knob.- Record the stable reading.- The results obtained are directly recorded.

13COLOUR – VISUAL COMPARISON METHOD

Colour refers to the true colour that is colour of water for which turbidity has been removed. The term apparent colour includes not only colour due to substances in solution but also due to suspended matter. This is done without filtration or centrifugation.

Principle It is done by visual comparison of the sample with special glass colour discs which has been properly calibrated

Determination

- Fill Nester tube with distilled water- Place the sample at the right side of the nesslerizer lighted cabinet- Place the distilled water in the left hand compartment for reference.- Switch the colour disc in the compartment and the light of the nesslerizer.- Rotate the disc until a colour match is obtained- Read the colour in Hazen from the disc - Dilute if colour exceeds 50 units - But if turbidity is removed then it becomes true colour

Calculation

Colour units (Hz) = A × 50 BWhere A = Estimated colour of diluted sampleB = ml of sample taken for dilution

TOTAL HARDNESS- EDTA TITRIMETRIC METHOD

Total hardness is defined as the sum of the calcium and magnesium concentrations in a water sample. Both are expressed as calcium carbonate in mg/L. this is what causes the precipitation of soap in water and can be removed basically through boiling.It may range from 0 mg/L to several hundreds depending on the level of treatment that the water has undergone.

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Principle

Ethylenediaminetetracetic acid (EDTA) forms complexes when they come into contact with sodium salts and certain metal cations. On addition of a dye such as Eriochrome Black T (EBT) to such a solution (containing metal cations in the form of calcium and magnesium), a wine red colour develops when the pH is 10±0.1, when EDTA is added as a titrant, the calcium and magnesium will be complexed. When sufficient EDTA complexes all the calcium and magnesium present, the endpoint colour of sea blue develops.

Method- Sample volume depends on the conductivity; the greater the conductivity, the greater the volume of EDTA needed to complex the calcium and magnesium ions, thus less volume of sample is needed.- Take 50ml of sample or an aliquot made up to 50ml into a conical flask.- Add 1ml of buffer solution (ammonium hydroxide buffer) to adjust to a pH within 10±0.1- Add a few crystals of Eriochrome Black T (EBT) indicator.- Mix constantly. Titrate with standard 0.01EDTA until the last traces of purple disappear or the colour turns bright blue.-record endpoint

Calculation

Total hardness = ml EDTA ×B ×1000ml sample

Where B=mg of CaCO3 equivalent to 1.00ml EDTA titrant.That is ml CaCO3

ml EDTA

CALCIUM – EDTA TITRIMETRIC METHOD

Calcuim dissolves out of practically all rocks and consequently detected in all waters. Waters from limestone areas contain more Ca2+. About 30-100mg/L than those with granite or siliceous sand (< 10mg) and those associated with gypsiferous shale may contain several hundred mg/L.

15 Principle

When EDTA is added to water containing both calcium and magnesium, it combines first with calcium that is present. Magnesium is largely precipitated as hydroxide and the indicator combines with calcium only.

Determination - Take 50ml of the sample.

Take less (10ml) and dilute to 50ml if conductivity is large.- Add 2ml of 1M NaOH solution- Add a few grams of murexide indicator- Titrate against EDTA titrant slowly, with continuous swirling until the colour

changes from salmon to orchid purple- Ensure that not more than 15ml EDTA is required in the titration.- Record the endpoint

Calculation

Ca (mg/L) = A*B*400.8 ml sampleWhere: A = ml of EDTA used

B = ml of standard calcium solution

MAGNESIUM – CALCULATION METHOD

It is common constituent of natural waters. It is a major contributor to hardness, and like calcium, forms scales and deposits on heating. Its concentration ranges from zero to several 100mg/L.

PrincipleCalcium and total hardness are determined by EDTA titrimetric method. This is done from the difference between total hardness and calcium hardness when these are expressed in the same units. Magnesium content is obtained by multiplying the magnesium hardness value by 0.243.

16 Method

It is done by difference between the total hardness and calcium hardness.

Calculation Calcium hardness first by:Calcium (mg CaCO3/L) = A×B×1000

ml of sample Where A = ml titrant for sample

B = mg CaCO3 = 1.0ml EDTA titrant at the calcium indicator endpoint

ORCalcium as MgCa/L = A×B×400.8

ml sampleCalculate magnesium hardness as mg/L CaCO3 = T/H – Ca hardnessMg/L mg = (T/H – Ca hardness) × 0.243Where 0.243 = atomic weight of mg/ molecular weight of CaCO3

CHLORIDE – ARGENTOMETRIC METHOD

Chlorine found in the form of chloride ion (Cl-) and is one of the major inorganic anions in water. Provides the salty taste produced in potable water. Variations in concentration are dependent on the chemical composition of the water. It is greater in waste water because it is an essential part of diet and passes unchanged through the digestive system. It may be present in higher concentrations near the coast because of leakage of sea water into the sewerage system. The range of determination is 2.0 – 250mg/L.It is important to carry chloride test on samples because chloride contributes to the salinity of water.

Principle

In slightly alkaline solution, potassium chromate can indicate the endpoint of the silver nitrate. Titrant of Chloride - silver chloride is precipitated quantitatively before reducing silver chromate is formed. Bromide, iodide, and cyanide register as equivalent chloride concentration.

17 Method

- Measure 50ml of clear sample - Add 1ml potassium chromate indicator solution.- Titrate against silver nitrate titrant to a brownish yellow endpoint.- If more than 25ml of the titrant is needed, a smaller quantity of

sample (10ml or 1ml) is measured and diluted to 50ml.- Estimate a reagent blank with a usual value of 0.2 – 0.3ml-record the endpoint

Calculation MgCl/L = (A-B) M 35,450

ml of sampleWhere A= ml of titration of sample

B= ml titration for blank M= molarity of A

NUTRIENT ANALYSES

SULPHATE

It is widely distributed in nature. Surface water, ground water, seawater and wastewater have varying concentration of sulphate.

Principle

Sulphate ion is precipitated in an acid medium with Barium chloride to form a

Barium sulphate crystal with uniform size.

Determination

- 10ml of sample is pipette into a test tube.- 0.5ml of conditioning reagent is added to the sample.- A few grams of Barium chloride is added. - Read at a wavelength of 520nm using a UV-VIS spectrophotometer.

18 NITRATE

This is the oxidized form of combined nitrogen found in natural water.

PrincipleNitrate (NO3-N) is reduced to nitrite with hydrazine sulphate. The nitrite ion originally present plus reduced nitrate ion is determined by diazotization with sulphanilamide and coupling with N-(1- naphthly-)–ethylenediamine dihydrochloride to form a highly coloured azo dye which is measured spectrophotometrically.

Determination- Pipette 10ml of sample into a test tube.- Add 1ml of NaOH- Add 1ml of reducing solution (a mixture of 10ml NaOH, 10ml Copper

sulphate and 8mlHydrazine sulphate solution)

- Heat in a water bath for 10 minutes at 60°C.- Cool and add 1ml of colouring reagent to obtain a pink colour.- Prepare an intermediate of 100mg/l from the 100mg/l control standard.- Prepare eight other control standards that is 0.2, 0.6, 0.8, 1.0, 2.0, 5.0 and

10mg/l. Read it on the spectrophotometer at 410nm to find the absorbance that will be used to plot a graph.

- Read the samples at a wavelength of 410nm and find it corresponding concentration on the plotted graph.

NITRITE

Nitrite is formed by oxidation of ammonium compounds or by reduction of nitrate.It is unstable since it is an intermediate stage in the nitrogen cycle. Concentrations in natural waters are in the range of some tenths of mg/l. This is however higher in industrial wastes. Nitrite concentration in samples can change rapidly due to bacterial oxidative or reductive conversions.

Principle1. The presence of high oxidants and reductants in the sample will readily

affect the nitrite concentration.

2. High alkalinity (>600mg/l as CaCO3) will give low results due to a shift in pH.

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3. Suspended solids interfere and can be eliminated by filtration.

Determination

- Pipette 10ml of sample into a test tube.- Add 1ml of colouring reagent.- Read absorbance using UV-VIS spectrophotometer at a wavelength

410nm.

PHOSPHATE (PO4-P) - STANNOUS CHLORIDE METHOD

Phosphorus is essential to the growth of organisms and can be the nutrient that limits the primary productivity of a body of water. It occurs in natural waters and wastewaters almost solely as phosphate (pyrometa and other polyphosphates), and organically bound phosphates.

PrincipleMolybdophosphoric acid is formed and reduced by stannous chloride to intensely coloured molybdenum blue .The absence of molybdenum blue at a wavelength of 690nm are proportional to the concentration of the phosphate in the sample.

Determination

- Pipette 10ml of the sample into a test tube - Add 0.4ml of ammonium molybdate- Add a drop of stannous chloride.- Read absorbance using the spectrophotometer at wavelength 690nm.

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CONCLUSION

Samples being analysed are stored in refrigerators at a temperature below 4 degrees celcuis if analyses cannot be carried on the day of sampling, this reduces the degrees of error among results due to particular which might notbe accounted for calculations.

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Most laboratory are carried out using the standard laboratory procedures for water and waste water analyses and the results compared to World Health Organisation (WHO) and Environmental Protection Agency(EPA) guideline values.

All equipments and machines are calibrated before experiments and this increases the accuracy of results.Also the laboratories are always kept clean before and after every day”s work.

Concluding, I recommend Water Research Institute to any individual or group of persons willing to carried out water quality tests of water samples because their procedures give effiecient and accurate results.

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RECOMMENDATIONS

From the short experience gained at the environmental chemistry laboratories,I recommend that the defective fume chamber in the waste water laboratory be repaired. Also I recommend that the waste water laboratory should be supplied with additional glassware and test tube fillers to reduce the pressure on the existing ones. Also nose mask should be provided for staffs working on waste water samples to avoid health implications.

Finally, incentives should be given to workers and interns to motivate them to contribute their quota to the overall achievement of the goals set down by the institution.

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APPENDIX

a. CSIR ----------------- Council for Scientific and Industrial Research b. WRI ----------------- Water Research Institutec. ECD ------------------ Environmental Chemistry Divisiond. HOD------------------- Head Of Departmente. BOD-------------------Biochemical Oxygen Demandf .COD-------------------Chemical Oxygen Demandg. TTFPP----------------Third Trimester Field Practical Programmeh. KNUST---------------Kwame Nkrumah University of Science and Technologyi. T-Poly------------------Takoradi Polytechnicj. UCC--------------------University of Cape Coastk. NSS personnel------National Service Scheme Personnell. UDS---------------------University for Development Studiesm.TSS--------------------Total Suspended Solidsn. TDS--------------------Total Disolved Solidso. TS----------------------Total Solidsp. B.Sc--------------------Bachelor of Scienceq. WHO-------------------World Health Organisationr. EPA---------------------Environmental Protection Agency

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REFERENCES

1. APHA, AWWA, WED (2008) Standard methods for the treatment of water and wastewater; 20th edition, Washington D.C.