NPTEL RCC LECTURE -02

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NPTEL RCC, LECTURE - 01

Total Hardness Of Water Using EDTA Method

Theory:

Hard water is genrally considered to be one which requires considerable amount of soap to produce foam or leather. Hard water cause scale formation in boilers heaters and hot water pipes. The rain water catches CO2 from the atmosphere when the water pass through CaCO3 rock in the Soil, these compounds make the water hard. Calcium and magnesium chlorides and sulphates also cause hardness There are two types of hardness: Temporary Hardness Permanent Hardness

Temporary Hardness:

This type of hardness is mostly caused by Ca(HCO3) or Mg(HCO3) OR both, therefore it is also called carbonate hardness, these compounds dissolve in water and form Ca2, Mg+2 and HCO3 ions which cause hardness H2O+ CO2--> H2CO3 CaCO3 + H2CO3 --> Ca(HCO3)2 Temporary hardness can be removed by Clark's method by adding limewater,Ca(OH)2 to the hard water. Ca(HCO3)2 + Ca (OH)2 -->2CaCO3 + 2H2O Mg (HCO3)2 + Ca (OH)2 --> Mg CO3 + CaCO3 + 2H2O As the magnesium carbonate and calcium carbonate are insoluble in water and settles down,

Permanent Hardness:

It is also known as non carbonate hardness and it is caused by CaCl2.MgCl2, CaSo4 and MgSO4, the ion exchange method is used for the removal of the permanent hardness sodium zeolite is added to hard water due to which calcium or magnesium zeolite is formed which is insoluble in water. Ca + 2Na (zeolite) --> Ca (Zeolite ) + 2Na + 2

Disadvantages of hard water:

Total hardness = (Final hardness reading - Initial reading) 1000/50. The following values give the type of hard water:

Hardness mg/lit as CaCO3  Hardness (mg/lit Type of water 0 - 75 Soft water 75 - 150 Moderately hand water 150 - 300 Hard water above 300 Very hard water

W.H.O guideline values:

W.H.O guideline value of hardness is 500mg/lit as CaCO3 Greater amount of soa is used. Scale formation reduces the life of boilers. Effect the digestive system of it contains MgSO2

Apparatus:

Conical Flask Funnel Burette Sand Beaker

Chemicals:

Buffer solution of hardness ferrochrome black tea EDTA solution of 0.02normality.

Procedure:

Take 50ml of water sample in conical flask. Add 1ml of buffer solution (Aluminum Hydroxide n Ammonium Chloride) of hardness1. Add 3 drops of ferrochrome black tea to the flask and shake well. Place the flask below the burette containing EDTA (Ethylene diamine tetra-acitic acid) solution of 0.02 normality. Note the initial reading of the burette and open the tape of the burette to allow the solution to flow in the flask. Note The Final Reading when the color of the water in the flask turn bluish.

Turbidity of Water sample Using Nephelometric Method

Theory:

Water is said to turbid when it is seen containing materials of suspension inside it. While turbidity may be defined as the measure of visible material in suspension in water,turbidity may be caused by algae or other organisms. it is generally caused by silt or clay. The amount and character of turbidity depends upon two things: Type of soil over which flows The velocity of flowing water When water becomes stationary, the heavier and larger suspended particles settle down quickly and the lighter and finely divided particles settles very slowly and even takes months. Ground water is less turbid because of low velocity of water. turbidity may be helpful for controlling growth of organisms by not allowing proper sunlight to water which is necessary for their growth on the other hand it is harmful as the organisms are handling to the suspended particles.

When water becomes stationary, the heavier and larger suspended particles settle down quickly and the lighter and finely divided particles settles very slowly and even takes months. Ground water is less turbid because of low velocity of water. turbidity may be helpful for controlling growth of organisms by not allowing proper sunlight to water which is necessary for their growth on the other hand it is harmful as the organisms are handling to the suspended particles. There are Various units for the measurement of turbidity which are: Standard turbidity unit[mg/lit or ppm] Jackson turbidity unit [J.T.U] Nephelometric turbidity unit [N.T.U] A device called nephelometric turbidity measures the turbidity of water in N.T.U the intensity of light after passing through the water gives a measure of turbidity of water.

WHO guideline value:

WHO suggested a guideline value for turbidity as [N.T.U]for disinfection the turbidity of water should be less than 1 N.T.U.

Apparatus:

W.H.O Nephelometric turbidity meter for marine solution of the sample by multiplying the scale reading by 0.9 N.T.U, 9 N.T.U, 99 N.T.U, test tubes and water samples.

Procedure:

Switch on the power supply and check the battery of the turbidimeter, Press the 1 N.T.U button and coincide the scale with zero by using focusing template. Again press 1 N.T.U button and coincide the scale with zero using the focusing template. A Standard formazine solution of N.T.U is placed on tubidimeter in the path of rays and scale is brought 9 n.t.u The Water sample is taken in a test and is placed in turbidimeter. Use A Cell rise if the turbidity is more than 100 N.T.U and get the turbidity dilution factor.

Suspended Solids Test of water sample

Suspended Solids of Given Water Sample Theory:

The total dissolved solids mainly consist of the test that acts as a check on detailed analysis. Another useful aspect is that electric conductivity can be continously recorded. Any sudden chang indicate a chang of water . A treatment method can be there fore instantly detacted. Determination of total solids is used in two operations. In developing a potencial source for public water supply we must know about total solids. This is the factor to divide the type or method to be used in softening water. Drinking water standard recommends the following: Max desirable criteria = 500mg/lit as dissolved solids Max permissible criteria = 500 mg/lit as dissolved solids W.H.O guideline value = 1000 mg/lit as dissolved solids

Apparatus:

Filter media paper, filter glass, suction motor and pumps. The suspended solids in a turbid river consist of finely divided silt silica and clay having specifc gravity ranging from 2.65 for sand to 1.03 for tlocculated mud particles containing 95%water suspended impurities are bacteria algae and silt causing tubidity while dissolved impurities are salt of calcium magnesium sodium nitrogen and H2S are also dissolved impurites. Mostly rain water have suspended solid contents usually well below 200mg/lit but the contents of large river in tropical countries are sometimes over 200mg/lit

Procedure:

Take a filter glass of known size and weight let it is W1 put the filter glass on the filter assembly attached with a suction motor pump, pour waste water sample ofover 50ml over the filter glass and switch on the water pump remove the filter paper after waste paper filter through it and put in dissector bring down the temperature. find out the weight of the filter glass along with the sample remain on the filter let it would be W2. Find the amount of suspended solids = (weight of filter + sample - (weight of filter)) x 100 Volume of Sample = (W2-W1) X 1000

Amazing Swimming pool

Carrying out a DIY project at home is tough, but what this man created in his backyard may be the greatest DIY ever. Back in March 2011, reddit user VonBubenberg’s dad decided that he wanted to change his unsightly backyard into a swimming pond. The reddit user took pictures of the steps that led to the completion of this amazing project.

The amazing part is that the father works in IT and the son is a business student. Neither are experts at projects like these, but the result is completely astonishing.

This is what the backyard originally looked like

 A project of this scale couldn’t be completed without some heavy machinery

 The water conduits lead to the garage where the filtration system will be installed

 Manual labor was also needed (this is the reddit user’s little sister)

 Layer of felt and plastic were added to the

bottom

 These barrels circulated the water through the pond’s filtration system

 More rocks were added, followed by a base layer of stones
Large decorative rocks were added to the pool

 After everything was completed, water was added

 And then some lights

 In Spring 2012, it was time to add to the pond
The completed swimming pond

Interview Questions

Explain why concrete barriers have curved surface profiles?

The concrete safety fencing are made to contain vehicles in their carriageway being travelled so as to reduce the chances of rebounding into the roads leading to more hazards. In the case of normal fencing upon vehicle crashes the fencing give away so as to absorb as much energy as possible henceforth reducing the impact on the vehicles. But in the case of concrete barriers their purpose is not to absorb energy of vehicles crashing into the barrier but to retain them. They have a curved design so as to allow the vehicles that hit them to slightly go up on the barrier but not overturn. They also prevent the vehicle from again getting back on the road by rebounds. This helps in vastly reducing the chances of other vehicle hazards.

Why is the use of granular sub-base in concrete carriageways not preferred, explain?

Some of the reasons why granular sub-base is not preferred in concrete carriageways:

> Sub bases are permeable and hence water can seep through them easily. The soil particles get pumped out through the joints on the application of traffic loads. This results in the creation of voids underneath the pavement structure. This leads to the weakening of the concrete surface and it can crack easily upon intense traffic loads.
> Instead if lean concrete is used for carriageways it greatly increases the strength of the roads and the load carrying capacity of the roads is increased.
> Sub-bases implementation requires a lot of workmanship which can lead to an un-uniform distribution of the sub-base. This can lead to the cracking of the carriageway when there is severe traffic loading.

Why are separation membranes used between concrete pavement slab and sub-base?

The purpose of separation membrane between the concrete pavement slab and the sub-base are as follows:

> The separation membrane reduces the frictional forces between the concrete slabs and the sub-base. The membrane aids the movement of the concrete slab in reference to the sub-base when changes in the level of the moisture and temperature occurs.

> It aids in the segregation of sub-base materials from freshly placed concrete.
> The separation membrane also helps in the reduction of cement and water loss in the form of immature concrete. Immature concrete greatly affects the strength of the concrete. It also affects the durability of it.
A good example of a separation membranes is polythene sheeting which is commonly used.

In the roof of a pumping station explain briefly the components of a waterproofing system.

The components of a typical waterproofing system on the roof of a pumping station are as follows:

> Right above the structural finish level of the roof ( concrete ) a uniform thickness screed is applied so as to facilitate the application of the waterproofing membrane. The surface provide for the membrane should always possess good cohesion properties and must be thin so as to prevent any un-uniformity. This thin layer also acts as a layer of thermal insulation.
> Right above this layer the waterproofing membrane is deployed to secure the water tightness of the roof.
> In order to enhance the thermal insulation of the roof an insulation board is sometime placed right above the waterproof membrane. The insulation board helps in the maintenance of a stable temperature in both weathers.

During reclamation how can the occurrence of mud waves can be rectified?

There are several solution to the rectification of the problem of mud waves:

> Complete removal of all the disturbed mud: This method can be considered to be one of the fastest methods. As soon as the disturbed mud is removed some filling material is used to replace the disturbed mud. But economically this method can be expensive as compared to others.
> Accelerated consolidation of disturbed mud: In this method surcharging loads are placed on top of the mud waves. Along with this band drains are installed to accelerate the consolidation process. This method is quite slow compared to the other methods.
> Partial removal of the disturbed mud: This method is the hybrid of the above two methods where the top layer is removed whereas the lower level is treated with the surcharging process.

In reclamation works what are the importance of geotextiles and sand?

The primary purposes of geotextiles and sand in reclamation works are as follows:

> Geotextiles: They are used to separate the marine mud from the reclamation fill. Also geotextiles are used as reinforcements in reclamation processes to increase its stability. It is still debated as to whether the usage of geotextiles is better or are the old processes followed are better as the performance has not been comparable to the conventional methods.

> Sand: In reclamation process sand is used to spread the load of any future public dumps placed on top of it. Sand also acts as a drainage for the excess pore water pressure of band drain installations.

Yamuna E-way

Complete power point presentation on Yamuna expressway.

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