Various types of Water Demands Formulae

Hi, How you doing?  In our previous article 'Introduction to Water Demands', we got introduced with the various types of water demands, in this article I will post the various formulae which are used to calculate the water demands in cities of different kinds.

• Fire Demand

Let's Q be the demand of water required in liters/minute. Rate of fire demand is sometimes treated as a function of population and is worked our on the basis of the empirical formulas:

• (1) Kuichling Formula

Where, Q = Amount of Water required in liters/minute.

P = Population in thousands.

• (2) Freeman Formula

• (3) National Board of Fire Under Writers Formula

(a) For a central congested high valued city

       (i) Where population < 200000

       (ii) Where population > 200000

            Q = 54600 lit/minute for first fire

     and  Q = 9100 to 36, 400 lit/minute for a second fire.

(b) For a residential city.

       (i) Small or low building,

            Q = 2,200 lit/minutes.

       (ii) Larger or higher buildings,

            Q = 4500 lit/minute

       (iii) High value residences, apartments, tenements

            Q = 7650 to 13,500 lit/minute.

       (iv) Three storeyed buildings in density built up sections.

            Q = 27,000 lit/minute.

(4) Buston's Formula

The probability of occurrence of fire, which, in turn, depends upon the type of the city served, has been taken into consideration in developing above formula on the actual water consumption in fire fighting for Jabalpur city of India. The formula is given as:

Where, R = Recurrence interval of fire i.e., period of occurrence of fire in years, which will be different for residential, commercial and industrial cities.

(R) minimum = 1 year.

   t = duration of fire in minutes,

  (t)minimum = 30 minutes.

• Per Capita Demand(q)

q = Total yearly water requirement of the city in liter/ (365* Design population)

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References:  Book - A Handbook on Civil Engineering IES, GATE, PSUs - Made Easy

Great Himalayan National Park(GHNP), Kullu is now a World Heritage site.

Hi, I know its not what you read in the environment Engineering classes, but this is really important for the environment Engineer to understand that our environment is safe when its ecological cycle is working and safe.

From the initial ages of our schools we have read about the interdependence of one organism to the other and then on to the various elements of the earth. Any break in our ecological cycle means the disturbance to the cycle and therefore disastrous ending of the life on the earth.
Recently I along with my colleagues and friends went to a place in the Himalayas known as Shanger, located in the Kullu district of Himachal Pradesh.

At the front of the Community training and Tourist Center Khopa Complex , Sainj Jeecanwala valley (GHNP)

On the way to Shanger we stopped at the Ropa service center of the GHNP(Great Himalayan National Park). This was the first time that I visited this place, it was mystical in its own manner. Place is filled with dense jungles supported on the steep mountains of the Himalayas.

I wondered how these pine trees maintain their vertical rise at such a steep mountains. The jungle supports a number of wild animals and various Himalayan shrubs with trees. If I was an animal living in that jungle, even if I was a leopard, I would have hated the density of the jungle. This was horrible.
I have seen only that part of the park, but it expands onto various mountain peaks of varying heights up to 5000 m to 6000 m heigh, and valleys of the Kullu district. There are many spots which makes it a perfect place for the trekkers and adventurers. There was a sign board, where various details of the various treks was written and mapped upon.

Lovely environment at Pundrik Rishi lake, Sainj, Kullu with (from left) Ajay, Ankit, Karun and Meeit 

Today it was on almost every kind of news papers of district Mandi(H.P.) that GHNP has been given an UNESCO's world heritage site status. This is a happy news in itself, because the park is a home of so many threatened animal and flaura and fona species.
I think that in today's world, where men has occupied the vast space of the world land, such parks has become a necessity. Man can not start again to live in jungles and also he can not just allow these animals to roam around in the cities.

These parks are the ways to save our ecological system. The only thing that itches a little onto mind is the fact that man has started to take control of almost every aspect of ecology in nature. In order to keep it safe, man has to put the constant efforts, without a break.

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Classification of Air pollution

Hi Dear,

This post is for the Civil Engineers studying Environmental Engineering.

• AIR POLLUTION

Air pollution is defined as "presence in outdoor atmosphere of one or more contaminants, such as dust, fumes, gas, mist, odor, smoke or vapor in quantities, of characteristics, of duration such as injurious to human, plant or animal life or to property.

• CLASSIFICATION OF AIR POLLUTION

Air pollution exists in three different categories:

1. Personal Air Pollution: This refers to the exposure of an individual to dust, fumes and gases. e.g. person indulges in cigarette, cigar or pipe smoking.
2. Occupation Air Pollution: This represents the type of exposure of individuals to potentially harmful concentration of aerosols, vapors and gases in their working environment.
3. Community Air Pollution: This represents most complex of the three varieties since it involves pollution from a variety of sources and contaminant and factors which cause adverse social, economic and health effects. Not only does community air pollution affect many individuals, but it can also exert a significant impact on man's total environment including plants, animals, property and the weather itself.

• SOURCES OF AIR POLLUTION

There are two main sources of air pollution:

• Natural air pollution sources:

here is the list of natural air pollutants:

1. Wind-blown dust
2. Smoke, fly-ash, gases from forest fires.
3. Micro-organisms
4. Gases and odors from swamps and marshes
5. Fog
6. Volcanic ash and gases

• Man made air pollution sources:

There are various man made sources/processes which produces dust such as, combustion of fuel at home oven, power plants, or in motor vehicles or from the burning of the refuse. Then dust is produced in various manufacturing processes such as in metallurgical plant. 

Similarly in chemical plants, in various agricultural activities such as crop spraying, field burning, and in nuclear energy activities such as ore preparation, nuclear fission and nuclear device testing etc. dust/gases in produced.

Noise Pollution (civil Engineering)-GATE, PSUs one liners

Hello there,

Here are one line statements that might be useful for your preparation for the GATE and PSUs examinations from the subject "Noise Pollution".

1. To express sound levels in decibels, sound pressure levels are usually adopted on a reference scale of 20 uPa(micro-Pascals).
2. Two sources generate noise levels of 90 dB and 94 dB respectively. The cumulative effects of these two noise levels on the human ear is 95.5 dB.
3. Pairs :  a) Ringlemann : To grade density chart of smoke   b) Pneumoconiosis : Disease caused due to coal dust  c) PAN : Secondary air pollutant   d) NIPTS : Responsible for permanent hearing loss   e) Sound foci :Formed when sound waves are reflected from convex surface   f) TTS : Responsible for temporary hearing loss
4. Acoustics of an auditorium is considered to be excellent when its reverberation time is between 0.50 to 1.50 sec.
5. Reflection noises can be abated by providing lining on walls and ceiling with sound absorbing materials.

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Distribution of water

Hello there,

The distribution pipe system consists of supply mains, sub-mains, branches and laterals.

• Types of pipe Networks:

Four types of pipe network is generally used. Anyone of which is used one either singly or in combinations for a particular place.

1. Dead end system : This type of layout may have to be adopted for older towns which have developed in a haphazard manner. This system is suitable for countries which expand irregularly. This is economic system.
2. Grid Iron System: This system is suitable for well-planned towns and cities. It requires larger number of sluice valves.  This is economically and also equal pressures.
3. Ring system or circular system: Equal pressure and multiple flow paths.
4. Radial system.

• Methods of Distribution of Water:

Water may be forced into distribution system in the following three ways:

1. Gravitational system
2. Pumping system or pumping without storage system.
3. Combined gravity and pumping system called pumping with storage system.

• Pressure in Distribution system:

Greater the design pressure, the costlier it will be, but will cause more convenience to the consumers.

• Valves:

1. Sluice valve or cut-off valve: Used to control flow of water through pipe lines.
2. Air Valve: Used to release accumulated air in pipe.
3. Score Valve: Used to remove silt in a pipe line.
4. Check Valve: Used to prevent entry of pollution into the pure water.

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Reference: GK Publishers: GATE 2013

Disposal of Solid Wastes and Refuse of society

Hello there,

What is Refuse?

All solids and semi-solid wastes of community , except human excreta and sullage is called refuse. It includes garbase, ashes, rubbish, dust etc.

Sullage: 

It includes liquid wastes from the bath rooms, kitchen sinks, wash basins etc.

• Garbage are putrescible organic wastes includes food articles, vegetable peelings, fruits peelings etc. When it is scientifically processed and composted, then it is possible to obtain valuable products, like grease, hog wood, fertilizer etc. Garbage normally weighs 450 to 900 kg/m3.
• Ashes are incombustible waste products(700 to 850 kg/m3).
• Rubbish: It includes all non-putrescible wastes except ashes. It includes paper, glass, rags, etc. (50 to 400 kg/m3).

The usual weight of refuse varies between 300 to 600 kg/m3.

In an average modern city, each citizen produces about 0.3 to 0.8 kg of solid domestic waste per day.

Disposal of REFUSE

• By Sanitary Land Filling

In low lying area, the refuse is filled up or dumped in layers of 1.5 m or so, and each such layer is covered by good earth of at-least 20 cm thickness so that refuse is not directly exposed. If the thickness of land-filling is large filling shall be done in layers, and each layer shall be left out for at-least seven days, and compacting by movement of bull, motors trucks etc. for its settlement, before starting filling the second layer of refuse.

1. The land-filling operation is essentially a biological method of waste treatment, since the waste is stabilized by aerobic as well as anaerobic process.
2. The refuse get stabilized, generally within a period of 2 to 12 months, and settles down by 20-40% of its original height.
3. This method is widely adopted in our country. 90% of Indian refuse is disposed off in this manner. 
4. Sanitary land fills may cause troubles during peak monsoons.
5. Leachate is a colored liquid, that comes out of sanitary land fills.
6. Quantity of refuse produced in an average Indian city or a town is of the order of 1/4 to 1/5 heefare/day.

• Burning or incineration: In this method this is fired.
• Burying it into the sea(obselete method)
• Pulverization
• By Composting 

Composting of refuse is a biological method of decomposing solid wastes. This decomposition can be effected either under aerobic conditions, or under anaerobic conditions, both. The final end product is a manure, called compost or humus.

In India following two methods are adopted:

1. Indoor method: It uses manual turning of piled up mass(refuse and night soil) for its decomposition under aerobic conditions
2. Bangalore method: It is primarily anaerobic in nature; This method is widely adopted by municipal authorities throughout the country. The refuse and night soil, in this method are therefore piled up in layers in an under-ground earthen trench(10cm*1.5cm*1.5cm). This mass is covered at its top by layer of earth of about 15 cm depth, and is finally left over for decomposition.

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Reference: GK Publishers, GATE 2013

Sewage Treatment (brief introduction)

Sewage Treatment

Sewage, before disposed off either in river streams or on land, has to be treated, so as to make it safe.

Sewage has to be treated for the following reasons:

1. To prevent pollution of water into which the sewage is let off, as water may be used downstream for drinking water supply. This causes health hazard as sewage contains pathogenic bacteria.
2. To prevent offensive odor in the water if water is used for swimming, boating, etc., and to the people living near the water or land where sewage is disposed off as it causes health hazard.
3. To prevent destruction of fish and other aquatic life.
4. If sewage has to be disposed of on land, soil will become sewage sick after some time and cannot take any more sewage. 

Sewage treatment process

It can be classified into the following four categories:

1. Primary sedimentation
2. Primary treatment
3. Secondary or biological treatment
4. Final or tertiary treatment(Disinfection).