Experiment of determination of pH , solids and hardness

EAA305 ENVIRONMENTAL ENGINEERING LABORATORYEXPERIMENT 1 USE OF pH METER, DETERMINATION OF ACIDITY AND ALKALINITY WATER SAMPLESEXPERIMENT 2. DETERMINATION OF SOIL AND HARDNESS IN WATER

CONTENT:EXPERIMENT 1 PAGE

a) USE OF pH METER 1

b) DETERMINATION OF ACIDITY

OF WATER SAMPLES

8

c) DETERMINATION OF

ALKALINITY OF WATER SAMPLES

14

EXPERIMENT 2

a) DETERMINATION OF SOLIDS IN

WATER

21

b) DETERMINATION OF

HARDNESS IN WATER

28

REFERENCE 37

DECLARATION 38

APPENDIX 39

GROUP 24 1 1


EAA 305 – ENVIRONMENTAL ENGINEERING LABORATORY

EXPERIMENT 1 :-

USE OF pH METER, DETERMINATION OF ACIDITY AND ALKALINITY

WATER SAMPLES.

Experiment 1a :- Use of pH Meter

OBJECTIVES:

The objective of this test is determined pH of the given water samples by using pH

meter and pH paper.

THEORY:

pH

‘pH’ is a numerical representation of acidic or basic nature of solutions.

Water ionizes to a small degree. The ionization is represented by:

H2O H + + OH -

Equilibrium constant, K = [H + ] [OH - ] [H2O]

Since ionization of water is very low, [H2O] is taken to be constant. Thus,

Ion product of water, Kw = [H +] [OH -]

= 1 × 10 -14 at 25 °C

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‘p’ Notation

pX = -log10 X

pH = -log [H+]

pH < 7 ; acidic solution

pH = 7 ; neutral solution

pH > 7 ; alkaline solution

In general,

pH + pOH = 14

APPARATUS:

o pH Meter,

o Volumetric Cone and

o Cylindrical

pH METER

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PROCEDURES:

a) At first we calibrate the pH meter with buffer solutions (pH 4.01 and

7.01).

b) We have rinsed the electrode of the pH meter with distilled water and

dry it with a piece of tissue paper.

c) Then we determine the pH value for the following water samples by

immersing the pH meter electrode into them.

i) Distilled water

ii) Laboratory tap water

iii) Untreated sewage sample

Notes: Rinse your electrode with distilled water and dry it with a piece of tissue

paper before measuring each sample’s pH

a) We have compared the results with those obtained by using pH paper

b) The result we obtained recorded.

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RESULTS:

Experiment 1a: Use of pH Meter

Sample

pH meter reading

I II III Average

(a ) Tap water 6.26 6.46 6.53 6.42

(b ) Untreated sewage

sample 6.87 6.94 6.97 6.93

Experiment 1a : Use of pH Meter

The pH of tap water sample = 6.42

The pH of untreated sewage sample = 6.93

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DISCUSSION:

Use of pH meter

pH-----The scientific definition is 'the negative logarithm of the Hydrogen ion concentration'. OK - don't give up - its a very important concept. Lets get through to that definition in every day terms.First accept pH is a scale measuring the acidity or alkalinity of a solution. Squeezed

lemon and vinegar are sour or acidic. If we drank them we would take something

alkaline like bicarbonate of soda or magnesia to neutralise the acidity in our stomachs -

in other words raise the pH. The pH scale runs from 0 (highly acidic) to 14 (highly

alkaline) with distilled water being neutral at pH 7.

1. Why is the pH value of distilled water acidic?

The quality of reagents is strongly dependent upon the quality of water to prepare them.

There must be no detectable concentration of the substances to be analyzed, or of

anything which will react with that substances in the water. For use in a laboratory

where multiple analyses are being performed, a source of the purest water available is

needed; distilled water. The quality can be checks by measuring the electrical

conductivity (pure distilled water does not conduct electricity) at temperature 25° C.

Distilled water contained amount of free hydrogen more than ion hydroxide.

This special characteristic have make the distilled water became acidic samples.

At the temperature 25ºC the condition of distilled water is constant, since the density of

ion hydrogen more than ion hydroxide, when we expose the distilled water to the

atmosphere for a period, it will become more acidic.

The reaction can be shown from the equation below:

CO2 + H2O = H2CO3 H2CO3 is weak acid.

It will cause the density of ion hydrogen in distilled water higher than the ion hydroxide:

2H2O + CO3 = H3O + HCO3-

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2. What is the significance of pH in water/wastewater treatment?

Aquatic organism treatment is sensitive to change of pH meter, and biology

treatment need for control of pH.

For the water treatment, pH also important to determine the chemical

treatment is successful to control disinfection and corrosion.

Also know that flowing water in mine usually yield the sulphuric acid

(concentration H+ is high) and hazardous to aquatic life.

The most important things to know the pH water is because to make sure

that we are drinking a safety water without any worried.

CONCLUSION:

The pH value is the negative logarithm to base 10 of the hydrogen ion

activity (mol/l) and is 7.0 in pure water (neutral point). This value changes in the

presences of acids and alkalis and through the hydrolysis of certain salts. In natural

water the pH ranged 6.5 to 8.5 the presence of free carbon dioxide or humus lowers the

pH. Biogenic decalcification in surface water, which occurs when there is high CO2

depletion by algae, can cause the pH to rise to 10.

pH Conc. H+ Example

0 10,000,000 Battery acid Most acidic

1 1,000,000 Hydrochloric acid

2 100,000 Lemon juice

3 10,000 Orange juice

4 1,000 Acid rain

5 100 Black coffee

6 10 Saliva

7 1 Distilled water Neutral

8 0.1 Salt water

9 0.01 Baking soda

10 0.001 Milk of magnesia

11 0.0001 Ammonia solution

12 0.00001 Soapy water

13 0.000001 Oven cleaner

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14 0.0000001 Liquid drain cleaner Most alkaline

The pH value we got in this experiment for samples laboratory tab water,

and untreated sewage sample were 6.42, and 6.93 respectively. So we can conclude that,

laboratory tab water and untreated sewage sample are acidic. The standard value for

wastewater is 5.5 to 9 (standard A) and 5.0 to 9.0 (standard B) respectively.

Experiment 1b: Determination of acidity

OBJECTIVE:

To determine various forms of acidity in the given water samples.

THEORY:

Acidity

Both CO2 and mineral acidity can be measured by titration with a standard alkaline

solution. Mineral acids are measured by titration to a pH of 4.5. Titration to the pH 8.3

end point measures total acidity i.e. both mineral acidity as well as due to weak acids.

APPARATUS:

o pH Meter,

o Volumetric Cone,

o Cylindrical,

o Retort Stand and

o Burette.

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PROCEDURES:

a) For samples with pH 0 – 4.5 (i.e. mineral acidity), we take 50ml sample and

titrate it using N/50 NaOH and methyl orange as indicator (colour change from

red to orange).

b) For samples with pH 4.5 – 8.3 (i.e. CO2 acidity), we take 50ml sample and titrate

it using N/50 NaOH and phenolphthalein as indicator (colour change from

colourless to pink).

c) We have recorded the concentration and type of acidity.

RESULT:

Experiment 1b: Determination of Acidity Water Samples

i. Laboratory tap water

Sample Volume = 50 ml

pH value = 2.96

Type of Acidity

Burrete Reading

Start (± 0.05 ml) End (± 0.05 ml)Volume of NaOH

(ml)

Mineral Acidity 16.10 27.60 11.50

Carbon Dioxide Acidity 27.60 40.10 12.50

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ii. Untreated sewage sample


pH value = 6.93

Type of Acidity

Burrete Reading

Start (± 0.05 ml) End (± 0.05 ml)Volume of N/50

NaOH (ml)

Mineral Acidity 40.10 43.50 3.40

Total Acidity 13.80 16.10 2.30

CALCULATION:

Determination of Acidity Water Samples

i ) Laboratory tap water

Sample volume = 50 ml

Mineral acidity = 230.00 mol/l Total acidic = 250.00 mol/l

Type of acidity = -

pH value = 2.96

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For Mineral acidity,Volume of N/50 NaOH (ml) = End reading - Start Reading

= 27.60 – 16.10= 11.5 ml

For Total acidity,Volume of N/50 NaOH (ml) = End reading - Start reading

= 40.10 – 27.60= 12.50ml

Mineral acidity = ml of N/50 NaOH x

= 11.50 x

= 230 mol/l

Total acidity = ml of N/50 NaOH x

= 12.50 x

= 250.00 mol/l

Carbon Dioxide acidity = Total acidity - Mineral acidity= 250.00 – 230.00= 20.00 mol/l

GROUP 24 11 11


DISCUSSION:

AciditypH is a measure of a water sample's deviation from a neutral value of 7.00, it

provides little information about a water sample's ability to neutralize acids or bases.

The standard procedures for "acidity" and "alkalinity", which have been modified here

to fit the time and equipment requirements of a student laboratory,

quantitatively provide that information.

The acidity of a water sample is its capacity to neutralize hydroxide ions.

Acidity may be caused by mineral acids such as sulfuric acid or hydrochloric acid or by

dissolved carbon dioxide. Most commonly in drinking water, carbon dioxide is the

principal cause of acidity. Acidity increases the corrosive behavior of water. Drinking

water with a high acidity is likely to be corrosive to copper water pipes and to the solder

which joins those pipes. High levels of copper and lead in drinking water often occur

when acidic water stands in pipes for extended periods of time (such as over night). In

addition to creating a possible health hazard due to dissolved metal ions, acidity in

water can cause copper plumbing to develop pin hole leaks after a few years.

Acidity is generally measured by titration with sodium hydroxide to an accepted

pH value. Phenolphthalein is an acid-base indicator which changes from colourless to a

pink (magenta) at a pH of about 8.3.

Generally, acidity is measured by titration of a water sample to pH 8.3 with

NaOH titrant. Metacresol purple also changes color at pH 8.3, but gives a sharper color

change than phenolphthalein. If available, its use is recommended over phenolphthalein.

If a water sample is at the alkaline color of the indicator before any titrant is added, then

the acidity is zero and the alkalinity of the water should be tested.

Because CO2 is the most likely cause of acidity in water, the water sample

should be collected within a few hours of the time of analysis. The container used to

collect the water should be filled completely and closed with an air-tight seal. A clean

plastic soft drink bottle with screw cap is suitable for water samples tested in this

procedure.

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1. What are the source of acidity in waste water?

Acidity may be caused by mineral acids such as sulfuric acid or hydrochloric

acid or by dissolved carbon dioxide. Most commonly in drinking water, carbon

dioxide is the principal cause of acidity. Acidity increases the corrosive behavior

of water.

Carbon dioxide, the major acid components of all natural waters, enters surface

waters by absorption from the atmosphere, and from aerobic and anaerobic

bacterial action in water.

Sewage water become a little bit acidic if anaerobic process takes

place.Beacause of the fact that anaerobic process produces methane gas (CH4),

carbon dioxide (CO2) and hydrogen sulphate (H2S). These gases can dissolve

into the water and decrease the pH value of sewage water making it more acidic.

Organic matter + Bacteria (CO2)

+ (CH4) + (H2S) +

(sewage water) (without the presence of oxygen)

new cell

2. What is the significance of acidity in water/waste water treatment?

It is this CO2 acidity that is monitored in the acidity test, and it can exist in

natural waters which are under a pH of 8.3 (phenolphthalein endpoint ). It is of

no direct health significance in drinking waters. Our natural stomach acid is

concentrated HCL, with a pH between 0 and 1. The value of monitoring CO2

content is in recognizing its capacity to react with other chemicals in the water.

If the waste water is either too acidic or too alkaline then further analysis will be

needed before any treatment is allowed. Thus, the lumping and flocking process

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will not occur at an optimal rate. Besides, water with a high value of acidity may

be harmful to human health, therefore the magnitude of acidity in water is

important.

CONCLUSION:

From the calculation based on the information we obtained, the result we get for

laboratory tap water sample:

Mineral acidity = 230 mol/lTotal acidity = 250 mol/lCarbon Dioxide acidity = 20 mol/lThe acidity is quite high if we refer the data above, so the treatment is required upon the water.

Experiment 1c : Determination of alkalinity

OBJECTIVE:

To determine various forms of alkalinity in the given water samples.

THEORY:

Alkalinity

Alkalinity of a water sample is defined as its capacity to neutralize acids. In natural

water alkalinity is generally due to the presence of the hydroxide (OH -), carbonate (CO3

2- ) and bicarbonate (HCO 3- ) ions.

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Alkalinity is measured by titration with a standard acid solution. The end points of

importance for the titration are those of pH 8.3 and 4.5.

APPARATUS:

o pH Meter,

o Volumetric Cone,

o Cylindrical,

o Retort Stand and

o Burette.

PROCEDURES:

a) We have taken 50ml of untreated sewage and add it with the appropriate

indicator.

b) (i) The pH of the sample is greater than 8.3, hence we titrate the sample by using

N/50 H2SO4 and phenolphthalein as indicator (colour change from pink

to colourless).

Phenolphthalein alkalinity (P) = ml H2SO4 (to pH 8.3) × 1000

ml sample

To the same sample add methyl orange indicator to find total alkalinity (colour change

from orange to red).

Total alkalinity (M) = total ml H2SO4 (to pH 4.5) × 1000

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ml sample

(ii) For the sample pH lies between 4.5 and 8.3 that means only bicarbonate

alkalinity is present. We titrate the sample with N/50 H2SO4 using methyl orange as

indicator (colour change from orange to red).

Total alkalinity (i.e. bicarbonate) = total ml H2SO4 (to pH 4.5) × 1000

ml sample

c) We have determine various forms of alkalinity with the help of following guide :

P = M ; all alkalinity is OH –

P = M/2 ; all alkalinity is CO3 =

P > M/2 ; predominant species are OH – and CO3 =

P < M/2 ; predominant species are CO3 = and HCO3 –

P = 0 ; all alkalinity is HCO3 –

RESULT:

Experiment 1c : Determination of Alkalinity Water Samples

i) Laboratory tap water


pH value = 9.5

Type of Acidity

Burrete Reading


NaOH (ml)

P 33.1 38.3 5.2

38.3 48.4 10.1

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M

ii) Untreated sewage sample


pH value = 6.43

Type of Acidity

Burrete Reading


NaOH (ml)

M 24.4 33.1 8.7

CALCULATION:

Experiment 1c: Determination of Alkalinity Water Samples

ii) Untreated sewage sample


pH value = 6.43

Total H2SO4 = 8.7 ml

Phenolftalein alkalinity (P) = 0

Total alkalinity (M) = total ml H2SO4 x 1000

ml sample

= 8.7 x 1000 / 50

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= 174 mol/l

Types of alkalinity = HCO3

- alkalinity (4.5 < pH < 8.3; all alkalinity is HCO3-)

DISCUSSION:

Alkalinity

Alkalinity is the measure of a water sample's ability to neutralize hydrogen ions

(its acid-neutralizing ability). Alkalinity may be caused by dissolved strong bases such

as sodium hydroxide or potassium hydroxide (and other hydroxide-containing

compounds), and it may also be caused by dissolved carbonates, bicarbonates, borates,

and phosphates. The measured alkalinity is the total of all of these species found in a

water sample. For the sake of simplicity, it is expressed in terms of mg CaCO3/L

although many species other than dissolved calcium carbonate may actually contribute

to the alkalinity.

One important environmental consequence of alkalinity is the ability of a body

of water to withstand acidification due to acidic precipitation or atmospheric deposition.

A body of water may have a fairly neutral pH, but if its alkalinity is low, it will be

readily acidified. A body of water with the same pH but with higher alkalinity will have

a greater buffer capacity and, consequently, a greater resistance to acidification.

The following figure shows the various combinations of alkalinity.

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Representation of titration of samples

Determine various forms of alkalinity with the following guide:

If P=M ; Hydroxide = M, all alkalinity is OH-

If P<1/2M ; Carbonate = 2P

Bicarbonate = M-2P, predominant species are CO32-

and HCO3-

If P=1/2M ; Carbonate = 2P, all alkalinity is CO32-

If P>1/2M ; Hydroxide = 2P-M

Carbonate = 2 (M-P), predominant species are OH-

and CO32-

If P = 0 ; Bicarbonate alkalinity = M, all alkalinity is HCO3-

Since the total alkalinity = 174 mg/l as CaCO3 and P = 0 and M = 8.7 ml. Therefore the

predominant species are bbicarbonate, HCO3-. Type of alkalinity is acid.

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1.Which ions other than hydroxide (OH - ), carbonate (CO 32- ) and bicarbonate

(HCO3- )can cause alkalinity in water?

Alkalinity is defined as the ability of water to resist a change in pH when acid is

added; it relates to the pH buffering capacity of the water. Almost all natural

waters have some alkalinity. This is nature’s mean keeping the pH neutral, and

stable, so that life can exist there. Three major ions contribute to total alkalinity.

However other ions such as organic nitrogen, ammonia nitrogen, nitrite

nitrogen, nitrate nitrogen, phosphate PO42- , sulphate SO4

2- , chloride Cl- ,

fluoride F- , and cyanide CN- can also cause alkalinity in water.

2.What is the significance of alkaliniy in water/waste water treatment?

Alkalinity is a beneficial feature of water, and does not necessarily indicate a

high pH. The amount of total alkalinity is just as important as the type of

alkalinity. Water with few thousand molecules of bicarbonates alkalinity has a

lot more buffering power than that same water with just a few molecules of

hydroxide alkalinity, and yet the pH of the water remains close to neutral.

Monitoring pH does not disclose much information about the amount of

alkalinity in water because basicity and alkalinity are not the same thing.

In the lumping and flocking process, alkalinity is an important factor because

the lumper agent, alum that is used will react with the alkalinity of water to form

a settlement of aluminium hydroxide. But, if this standard of alkalinity is not

reach then the settlement will not occur at its optimal rate. Water which have a

low value of alkalinity will show some behavior of erodibility

CONCLUSION:

Relative to the pH scale the various type of alkalinities reside. In other words,

these ions have the capacity to hold to the pH of the water at these ranges, depending on

how much of each is represent. Now picture titrating with an acid into a water with

carbonate alkalinity. By the time pH 8.3 is reached, exactly half the carbonate alkalinity

has been neutralized. This is always the case. One of the reasons that phenolphthalein

GROUP 24 20 20


was chosen as a useful indicator for this method was that it does visually show this

point.

The total alkalinity of the effluent sample obtained from the experiment is 174

mg/l as CaCO3 with P = 0 and M = 8.7 ml. Therefore the only predominant species is

bicarbonate ions (HCO3-). Since the pH of the effluent sample is only 6.43 which does

not exceed 8.3, therefore the effluent alkalinity is at its required standards for alum to

react with suspended solid and settle as sludge. The alkalinity in water plays an

important role in waste water treatment especially in the lumping and flocking process.

EXPERIMENT 2 : DETERMINATION OF SOLIDS AND

HARDNESS IN WATER

Experiment 2a : Determination of solids in water

OBJECTIVES:

To determine the amount of total solids (TS), suspended solids (SS) and

volatile suspended solids (VSS) in the given wastewater samples.

THEORY:

Solids in wastewater

Considerable information can be gained on a wastewater sample by determining its

various solid contents. Various types of solids in wastewater samples can be determined

gravimetrically.

Solids - Water normally contain solid material, both in dissolved and suspended forms. Solids are also further classified as fixed or volatile. Fixed solids are basically the ash

GROUP 24 21 21


left over after burning the dried solids; volatile solids are those that are lost in this procedure. The sum of the two is referred to as total. Volatile solids are often used as an estimate of the organic matter present.

Total solids (TS) are determined by drying a known amount of a sample at a temperature of 103 to 105 °C. Results can be expressed in mg/l or percent by weight.

If the sample is then burned in a furnace at about 500 C, cooled, and weighed, the fixed (FS) or volatile solids (VS) can be determined. If the original sample is filtered through a tared glass-fiber filter, which is then dried, the weight of the material captured on the filter is used to figure the total suspended solids (TSS). Burning the filter in the furnace allows measurement of volatile suspended solids (VSS) or fixed suspended solids (FSS). The dissolved solids (DS) can be estimated from the difference between the total solids and the total suspended solids, but the official method calls for drying the filtrate (the liquid which passes through the filter) in a dish at 180C. Of course, there are TDS, FDS and VDS.

Suspended material can decrease the depth of the body of water. If there is a lot of biodegradable organic material in the sediment, it will become anaerobic and contribute to oxygen depletion. Toxic materials can also accumulate in the sediment and affect the organisms which live there and can build up in fish that feed on them, and so be passed up the food chain, causing problems all along the way . Also, some of the particulate matter may be grease-- or be coated with grease, which is lighter than water, and float to the top, creating an aesthetic nuisance.

APPARATUS:

o Volumetric Cone,

o Cylindrical,

o Filtration Unit,

o Vicar and

o Heat Bowl

PROCEDURE:

a) Total solids (TS)

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(i) Dry a crucible in an oven at 104 ˚C for one hour.

(ii) Cool the crucible in a desiccator and weight on an analytical balance to the

nearest 0.1 mg. (X)

(iii) Pour a suitable volume of sample into the crucible and evaporate the contents to

dryness on a steam bath.

(iv) Transfer to an oven at 104 ˚C and dry to a constant weight (about 30 minutes).

(v) Cool the crucible in a desiccator and weight on an analytical balance to the

nearest 0.1 mg. (Y)

(vi) Calculate TS as:

Total solids (TS) (mg/l) = (Y – X) × 1000

volume of sample (ml)

b) Suspended solids (SS)

(i) Prepare glass fibre filters GF/C.

(ii) Dry in an oven at 104 ˚C for 15 minutes.

(iii) Heat to constant weight at 550 ˚C in a muffle furnace (about 15 minutes).

(iv) Cool in a desiccator and weight on an analytical balance to the nearest 0.1 mg.

(X)

(v) Filter a suitable volume of sample.

(vi) Dry at 104 ˚C for an hour.

(vii) Cool in a desiccator and weight on an analytical balance to the nearest 0.1 mg.

(Y)

(viii) Calculate SS as:

Suspended solids (SS) (mg/l) = (Y – X) × 1000

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c) Volatile suspended solids (VSS)

(i) Ignite the glass fibre filters, from b) above, at 550 ˚C for 15 minutes.

(ii) Cool in a desiccator and weight on an analytical balance to the nearest 0.1 mg.

(Z)

(iii) Calculate VSS as:

Volatile suspended solids (VSS) (mg/l) = (Y – X) × 1000


RESULT:

Determination Of Suspended Solids (SS)


Sample weight (g)Y (weight of filter paper A + dry sample) 0.3027X (weight of filter paper A) 0.3368Y - X (weight of dry sample) 0.0341Suspended solids (mg/l)** 341.0000

Determination Of Volatile Suspended Solids (VSS)


Sample weight (g)Y (weight of filter paper B + dry sample before ignite) 0.3339X (weight of filter paper B) 0.3367Z (weight of filter paper B + dry sample after ignite) 0.0028

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Volatile suspended solids (mg/l)** 28.0000

Determination Of Total Solids (TS)


Sample weight (g)Y (weight of crucible) 91.4074X (weight of crucible + dry sample) 91.4095Y - X (weight of dry sample) 0.0048Suspended solids (mg/l)** 21.0000

CALCULATION:

Suspended solids

Suspended solids (SS) (mg/l) =

= (0.3368 - 0.3027 ) x 1000 100

= 341.0000mg/l

Total Solids

Total solids (TS) (mg/l) =

= (91.4095 – 91.4074) x 1000 100

= 21.0000mg/l

Volatile Suspended Solids

Volatile suspended solids (SS) (mg/l) =

= (0.3367 – 0.3339) x 1000 100

=28.0000 mg/l

GROUP 24 25 25


DISCUSSION:

1.What is the significance of various types of solids in water quality?

There are few types of solids in water. Total Dissolved Solids (TDS) consist mainly of

carbonates, bicarbonates, chlorides, sulfates, phosphates, nitrates, calcium, magnesium,

sodium, potassium, iron, manganese, and a few others. Total Suspended Solids (TSS) is

comprised of organic and mineral particles that are transported in the water column.

Total suspended solids (TSS) gives a measure of the turbidity of the water.

Solids in water are harmless to people, unless they exist in high amounts. Small

amounts of chlorides are necessary for normal cell functions in plant and animal life.

However, fish and aquatic animals can not live in high levels of chlorides. Phosphorus

is a necessity for all plant life, and nearly all fertilizers contain phosphates.

Suspended solids (SS) cause the water to be milky or muddy looking due to the light

scattering from very small particles in the water. Sometimes it is mixed with color, but

colored waters can also be clear. Normally, we notice suspended solids before we notice

anything else.

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Suspended solids reduce light penetration and submersed plant productivity. Suspended

solids also affect organisms that live in the water. Those organisms that depend on

plants for food and predators that rely on their visual abilities to hunt are adversely

affected. Suspended solids in a body of water also accelerate the process of

eutrophication. Eutrophication is the process whereby bodies of water become

fertilized. This fertilization causes a significant increase in the growth rate of algae and

other aquatic plants. With continued eutrophication, dissolved oxygen levels become

depleted further accelerating the process of eutrophication leading to eventual aquatic

collapse.

High levels of total dissolved solids can adversely industrial applications requiring the

use of water such as cooling tower operations; boiler feed water, food and beverage

industries, and electronics manufacturers. High levels of chloride and sulfate will

accelerate corrosion of metals.

2.What precaution must be taken in VSS determination? Why?

The main function of the desiccator is to remove all the moisture exist on the surface of

the filter paper. Therefore the ignited filter paper should be put into the desiccator

before we weighing it, as the moisture exist on the surface of the ignited filter paper

may bring significant affection to the final weighing result.

CONCLUSION:

From the experiment, the effluent sample solid component comprises of suspended

solid and volatile suspended solid. The suspended solid content must be acknowledged

to simplify the waste water treatment process. Parameter values from the experiments

are as below.

Suspended solid = 341mg/l

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Volatile suspended solid =21 mg/l

Total solid = 28mg/l

The allowed suspended solid in waste water is only 100 mg/l as stated in Environmental

Quality Act 1974. This is because suspended solid contains organic substances that are

the main parameter of wastewater.

Experiment 2b : Experiment of hardness

OBJECTIVES:

To determine total, Ca and Mg hardness in the given wastewater samples.

THEORY:

Hardness

Hardness is the presence of multivalent metallic cations in solution. Metal ions like Ca 2+, Mg 2+, Fe 2+, Mn 2+, Sr 2+ and Al 3+ would all contribute hardness.

However, in natural waters the major hardness contributing ions are Ca2+

and Mg 2+. Thus, generally total hardness is taken as the sum of Ca and Mg hardness.

Hardness of a water sample is determined by titration with ethylenediaminetetraacetic

acid (EDTA).

The amount of dissolved calcium and magnesium in water determines its "hardness."

Water hardness can be calculated as shown in the equation :

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Hardness (mg/l) = 2,5 [conc. of Ca2+ (mg/l)] + 4,1 [conc. of Mg2+ (mg/l)]

The most frequently used standard classifies water supplies is shown in the following table.

Hardness Scale

Classification Range of hardness (ppm)

Soft 0 - 60

Moderately Hard 61 - 120

Hard 121 - 180

Very Hard >180

APPARATUS:

o Volumetric Cone,

o Cylindrical, Vicar,

o Heat Bowl

Filtration unit heat bowl

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http://www.italocorotondo.it/tequila/module2/analysis/chemical_analyses.htm#analisi%20di%20routine%23analisi%20di%20routine%00


Volumetric Cone, Cylindrical and beaker

PROCEDURES:

a) Total hardness

i) We have measured 100 ml of sample diluted to 100ml with distilled water into a

250 ml conical flask (hardness between 10 – 200 mg/l as CaCO3).

ii) 2 ml of ammonia buffer solution added in sample to get pH 10.

iii) 1 drop of Eriochrome Black T (EBT) added as indicator and mix it with the

sample.

iv) Then we titrate the sample with M/100 EDTA (colour change from red to

blue/grey).

v) The total hardness calculated as:

Total hardness (mg/l as CaCO3) = ml EDTA × 1000

ml sample

b) Ca hardness

GROUP 24 30 30


(i) We measure 100 ml of sample or a suitable volume diluted to 100ml with

distilled water into a 250 ml conical flask (hardness between 10 – 200 mg/l as

CaCO3).

(ii) 1 ml of 4 N NaOH added into sample and stirs it. The pH of the solution should

be 12 – 13.

(iii) 1 spatula of murexide added as indicator and mix it.

(iv) We titrate the sample with M/100 EDTA (colour change from red

to blue).

(v) Ca hardness calculated as:

Ca hardness (mg/l as CaCO3) = ml EDTA × 1000

ml sample

c) Mg hardness;

The Mg hardness calculated as:

Mg hardness = Total hardness – Ca hardness

RESULT:

Total Hardness

Sample volume = 100 mlIndicator = EBT

Type of sample

Burette Reading

End(0.05 ml)

Start(0.05 ml)

Volume of EDTA (ml)

Untreated water 12.10 7.50 4.60

Colour of indicator change from : red to blue

Calcium Hardness

GROUP 24 31 31


Sample volume = 100 mlIndicator = murexide

Type of sample

Burette Reading

End(0.05 ml)

Start(0.05 ml)

Volume of EDTA (ml)

Untreated water 15.30 12.10 3.20

Colour of indicator change from: purple to dark purple

CALCULATION:

For Total Hardness,Volume of EDTA (ml) = End reading - Start Reading

= 12.10 – 7.50= 4.60 ml

For Calcium Hardness,Volume of EDTA (ml) = End reading - Start reading

= 15.30 – 12.10= 3.20 ml

Total hardness (mg/l as CaCO3) =

= 4.60 x 1000 100

= 46.00 mg/l as CaCO3

Calcium hardness (mg/l as CaCO3) =

= 3.20 x 1000 100


Magnesium hardness = Total Hardness - Ca Hardness= 46.00 – 32.00

GROUP 24 32 32



DISCUSSION:

Hardness

Hardness is defined as the sum of the concentrations of calcium and magnesium

ions dissolved in water. These two ions are the major hardness constituents, and though

some other metals contribute to hardness, their concentrations in natural waters are so

much smaller that their significance as hardness is negligible.

Calcium is the most abundant dissolved cationic constituent of natural fresh

waters, and is widely distributed in the minerals of rocks and soil. It is fifth most

abundant element on earth and is found in every major land area of the world.

Magnesium is also a major constituents of rocks, in abundance second to

calcium ( about fifth as much ), and is usually found in occurrence with calcium.

The carbonate salts of calcium are the major source of dissolved calcium and are

generally referred to as limestone or calcite. They include Iceland spar ( pure ), marble

and alabaster ( less pure and more compressed ), and chalk. They can be white or

colorless. Calcium carbonate is quite isoluble in pure water and dissolves only up to 15

mg/l, but if CO2, is represent, this natural acidity make the lime stones much more

soluble. This often occurs in groundwater; bacterial action in the soil release CO2,

GROUP 24 33 33


changing the carbonates to bicarbonates, and dissolving large amounts of calcium into

the water. Because of this, groundwater is generally harder waters than surfaces water.

Hard water typically contains high concentration of Ca , Mg (and other) cations

which interfere with the use of the water for many application .(For example the ions

diminish the effectiveness of soaps and detergens for cleansing operations , they

diminish the drinking quality of water and contribute to accumulation of insoluble salt

deposit in storage vessels or plumbing.)

1.What are problems associated with hardness in water?

Hardness in the water’s effect on scaling, corrosion, and soap. With hard water it

is difficult to produce a soap lather.

Hard waters leave spot on glasess, digny film on laundry and hair and crusty

deposits on bathroom fixtures.

The hardness will obstruct the soap bubbling and will cause sediment of ion

carbonate precipitate in the pipe and cause the pipe to be choked. It will cause

the escalating of the cost of curing the wastewater.

2.Differentiate between carbonate and non-carbonate hardness?

Carbonate hardness – the hardness ion associated with carbonates and

bicarbonates ( CaCO3, Ca(HCO3)2, Mg(HCO3)2 ). A consumer term, temporary

hardness was formerly used for this type of hardness ( it precipitates when the

water was boiled, and therefore, is temporary ). It is of interest to all utilities to

keep track how much of the hardness is carbonate hardness, for this is the

component that is associated with scaling tendency in distributions piping. It

relates to the amount of alkalinity in the water.

Carbonate hardness is hardness combined with the water’s alkalinity.

GROUP 24 34 34


Noncarbonate hardness – The hardness ions associated with other anions

(CaSO4,MgSO4,MgCI2). Previously termed permanent hardness because it could

not be made to precipate by boiling the water.

The major significance in separating carbonate from nancarbonate hardness is for

water-softening calculations. Lime and soda ash dosage will depend upon the

concentrations of each two types of hardness.

If the total hardness is greater than the total alkalinity, then the difference

between them is the nocarbonate hardness.

3.Why are samples adjusted to different pH values for total and Ca hardness

determination?

The unit of the hardness is stated in CaCO3 equivalent . The water is defined as

Hard water if the hardness of the water is more than 150 mg/l as CaCO3

equivalent.And the value of soft water have the hardness in between 50-60

mg/l as CaCO3 equivalent.

4.Briefly describe the methods for hardness removal?

Process of removing hardness from water is called softening. Water softening is

a measurement of calcium and magnesium are needed to determine chemical

dosage for lime/ soda ash softening plants and the size of ion exchange softening

units.

Hardness is mainly caused by the presence of calcium and magnesium salts.The

lenght of time that water is in contact with the hardness –producing material is

one factor that determines how much hardness there is in the raw water.The

soften water by the lime or soda-ash method , its degree of alkalinity has to be

considered.

The alkalinity of a water is a measure of the water’s capacity to neutraliza

acids.Many of the chemical used in water treatment , such as alum , chlorine or

lime, cause changes in alkalinity.

GROUP 24 35 35


Two basic methods of softening water are chemical precipitation and ion

exchange.Other methods can also be used to soften water such as

electrodialysis , distillation , freezing and reverse osmosis.

Chemical precipitation is one of the more common methods used to soften

water.The chemical normally used are lime ( calcium hydroxide , Ca(OH)2 ) and

soda ash ( sodium carbonate , Na2CO3).

Lime is used to remove the chemical that cause the carbonate and magnesium

non-carbonate hardness.Soda ash is used to remove the chemical that cause the

non-carbonate hardness.

When the lime and soda ash are added , the hardness-causing minerals form

nearly insoluble precipitates.When calcium hardness is removed in a chemical

softener , it is precipitates as calcium carbonate (CaCO3).When magnesium

hardness is removed is a chemical softener , it is precipitated as magnesium

hydroxide (Mg(OH)2.

CONCLUSION:

From our experiment, we discover that our sample is good for experiment. From

calculation, we got very high notes for effluent sample that we used for experiment. The

result is:

Total hardness: 46.00 mg/l as CaCO3

Calcium hardness: 32.00 mg/l as CaCO3

Magnesium hardness: 14.00 mg/l as CaCO3

We’ve learnt that from our syllabus, those water need to recycle to be drink or for

housework to be done. The data shows that the total hardness is more that it should be.

From books, we already know that total hardness for water is given the value of 500 and

below. So, the sample is totally can be drink daily as the experiment show. After all, we

just have to remove the colour and the water is ready to be drink. We’ve refer to the

Malaysian Standard for water drinking to determine total hardness that the water should

GROUP 24 36 36


have. Finally, it is shown that hardness is a factor, besides other factor as pH, the colour

and minerals in the sample

REFERENCE:

1. Introduction To Environmental Engineering,3rd Edition, Mackenzie L.Davis,

McGraw-Hill, ms 133-160

2. Water & Wastewater Engineering Volume 2,Gordon Maskew, John Charles Geyes & Daniel Alexander Okun,John Wiley & sons

3. Kejuruteraan Air Sisa, Kualiti Air dan Air Sisa, Hamidi Abdul Aziz (1999),

Utusan Publication & Distributors Sdn Bhd, ms 19-30

4. Kejuruteraan Air Sisa, Modul 1, Dini Ramya Hasan Basri, ms 15-20

5. Bekalan Air, Pembetungan dan Pengiran, Nik Ahmad Fuaad Nik Abillah, ms

61-74.

GROUP 24 37 37


DECLARATION

E1 USE OF pH METER, DETERMINATION OF ACIDITY AND ALKALINITY WATER SAMPLES, DETERMINATION OF

SOLIDS AND HARDNESS IN WATER8 JULY 2004

WE, hereby make the declaration that we have successfully carry out the experiment with cooperation from each member in the group. In order to complete this lab report we have equally divided the jobs to every member in the group.

NAME MATIRC NUM. JOB SIGNATURETING PING WANG 70260 EDIT, REFERENCE,

DECLARATIONIVAN LASANUL TSEN SAM PAK

70178 PROCEDURE,TEORY, APPARATUS

MOHD. MAZRI BIN ZAHARI

72917 CALCULATION

MOHD. OZAIRIEE 70210 RESULT

GROUP 24 38 38


ABDUL AZIZMARSHIDAH MUSTAPA

70195 DISCUSSION, CONCLUSION

APPENDIXGROUP 24 39 39


GROUP 24 40 40

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Experiment of determination of pH , solids and hardness

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