gate material - civil engineering, environmental engineering book

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Environmental Engineering

for

Civil Engineering

By

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Syllabus Environmental Engineering

THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th

Cross, 10th

Main, Jayanagar 4th

Block, Bangalore-11

080 65700750 i f @th t d C i ht d W b th t d

Syllabus for Environmental Engineering

Quality standards, basic unit processes and operations for water treatment. Drinking waterstandards, water requirements, basic unit operations and unit processes for surface water

treatment, distribution of water. Sewage and sewerage treatment, quantity and characteristics ofwastewater Primary, secondary and tertiary treatment of wastewater, sludge disposal, effluent

discharge standards. Domestic wastewater treatment, quantity of characteristics of domestic

wastewater, primary and secondary treatment Unit operations and unit processes of domestic

wastewater, sludge disposal.

Types of pollutants, Their sources and impacts, Air pollution meteorology, Air pollution control,

Air quality standards and limits.

Characteristics, generation, collection and transportation of solid wastes, Engineered systems

for solid waste management (reuse/ recycle, energy recovery, treatment and disposal)

Impacts of noise, Permissible limits of noise pollution, Measurement of noise and control of

noise pollution

Analysis of GATE Papers

(Environmental Engineering)

Year

Percentage of marks

Overall Percentage

2013

8.00

13.36

2012 10.00

2011

11.00

2010

14.00

2009

12.00

2008

12.67

2007

14.67

2006

16.00

2005

13.33

2004

17.33

2003

18.00


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Contents Environmental Engineering

THE GATE ACADEMY PVT.LTD. H.O.: #74, KeshavaKrupa (third Floor), 30th

Cross, 10th

Main, Jayanagar 4th

Block, Bangalore-11

080 65700750 i f @th t d C i ht d W b th t d P II

Assignment 1 85 86

Assignment 2 87 88

Answer Keys

Explanations

8989 90

4 Sludge Disposal 91 110

Digestion and Disposal of Primary &Secondary Sludge

91 96

Design Consideration Involved in An ActivatedSludge Plant

96 98

Effluent Disposal

Solved Examples

98 99100 103

Assignment 1 104 105


Answer Keys

Explanations

108108 110

5 Domestic Waste Water Treatment 111 122

Characteristic of Domestic Waste Water 111 112

Treatment of Domestic Waste Water 112 113

Chemical Treatment 113 114

Sludge Disposal 114 116



Answer Keys

Explanations

120

120 122

6 Air Pollution 123 138

Introduction

Air Pollution System

123123 129

Zone of Atmosphere 129

132

Monitoring of stack emissions 132 137

Filter Cleaning Method 137 138

7 Solid Waste 139 156

Classification fo Solid Waste 139 140

Physical Properties of MSW (Municipal SolidWaste)

140 142

Importance of waste transformation 143 152

Sources of hazardous waste in MSW 152

155


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Contents Environmental Engineering

THE GATE ACADEMY PVT.LTD. H.O.: #74, KeshavaKrupa (third Floor), 30th

Cross, 10th

Main, Jayanagar 4th

Block, Bangalore-11

080 65700750 i f @th t d C i ht d W b th t d P III

Solved Examples 155 156

Module Test 157 169

Test Questions 157 164

Answer Keys

Explanations

165165 - 169

Reference Book 170


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Chapter 1 Environmental Engineering


Cross, 10th

Main, Jayanagar 4th

Block, Bangalore-11

080 65700750 i f @th t d C i ht d W b th t d P 1

CHAPTER 1

Quality Standards of Water

Municipal water supply: Sources

Raw water sources:The various sources of water can be classified into two categories

1. Surface sources

i)

Ponds and lakes

ii) Stream and rivers

iii)Storage reservoir

iv)

Ocean, generally not used for water supplies at present technologies are available

2. Sub surface water sources or underground sources

i) Springsii) Infiltration wells and

iii)

Wells and rife wells

Water Quality and Standards

Water quality and standards are defined on the basis of analyzing the raw water on their

physical chemical and bacteriological characteristics

Physical Characteristics

i)

Turbidity

ii) Colouriii) Taste and odour

iv) Temperaturev)

Specific conductance

Turbidity: If a large amount of solids are present in water it will appear turbid in appearance.

Turbidity depends upon the finess and concentration of practices present in water

It is expressed as the amount of suspended matter in mg/L or ppm

Measurement

(a)

For field Turbidity rod(b) For Lab

(i) Jacksons turbidity meter(ii)

Nphelometer is used for treated water. Nephelometer can measure turbidity less

than 1 ppm

NTU Nephlometer Turbidity unit

The IS value for drinking awter is 10 25 NTU


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Cross, 10th

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Colour: Dissolved organic material from decaying vegetation or inorganic materials may importcolour to the water.

The standard unit of color is that which is produce by one mg of platinum cobaltdissolved inone liter of distilled waterThe IS value for treated water is 5 to 25 cobalt unit.

Taste and Odour: Mostly organic and inorganic material originating from municipal or industrial

waste contribute taste and odour to the water. Taste and odour can be expressed in terms of

odour intensity and threshold values.

Temperature:The increase in temperature decreases palatability (pleasant in taste), because at

high temperature CO2 and some other volatile gases are expelled.

The ideal temperature of water for drinking purpose is 5 to 120C

Specific conductance: Presence of salt can be estimated by measuring specific conductivity

(unit: mho/cm)

Chemical characteristics

i)

pH

ii) Acidityiii) Alkalinityiv) Hardness

v)

Chloridesvi)

Iron solids

vii) Nitrates

pH: pH value denoted about the alkalinity and Baricity of the water. It is the logarithm of the

reciprocal of the hydrogen ion concentration pH = log * +The values of PH for drinking water must liest between 6.5 to 8.5

Acidity: It is caused by the presence of uncombined CO 2mineral acids or salts of strong acids

and weak bases. It also salts of strong acids and weak bases. It also determines the measures of

capacity of water to neutralizes the measures the base.

It is expressed as mg/L in terms of Desirable 200 mg/L permissible limit 600 mg/L

Hardness

It is the characteristics of water which prevents formation of lather or foam when mixed withthe soap

It is usually caused by divalent ion of calcium and magnesium ( )

Hardness

Temporary hardness permanent hardness

(due to presence of (Due to presence of sulphatesCarbonate and bicarbonate chlorides and nitrates.)


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Of and in water) The major anions associated with the hardness are sulphates, carbonates, bicarbonates,

chlorides and nitrates The total hardness (TH) is defined as the sum of concentration of mg and Ca ion and is

expressed in terms of in mg/LT.H (mg|L)

= (mg|L) T.H =(mg|L) g

Non carbonate ions cannot be precipitated or removed by boiling add, hence it is called

permanent hardness

Desirable limits 300mg/L as Permissible limit 690mg/L as

If hardness 75ppm > soft water

If hardness lies between 75-200 => moderate hardnessif hardness > 200 => hardnes

Chlorides Content

In the form of NaCl

Permissible limit 250 mg/L Chloride concentration is detected by titrating water with standard silver nitrate

solution using as indicator

Sulphates: Sulphates occur in water due to leaching from sulphate mineral and oxidation ofsulphides

Sulphates desirable limit = 150 mg/L

Permissible limit = 400 mg/L

Iron: When ferric oxide comes in contact with water it converts into ferrous bicarbonate and

further it oxidieses to ferric hydroxide ppt under favorable conditions.

Desirable limit 0.3 mg/LPermissible limit 1.0 mg/LNitrates:Nitrates in surface water occurs by leaching of fertilizers from soil during surface run-

off and nitrification of organic matter

Desirable limit for drinking water = 45 mg/L

Permissible limit for drinking water = 100 mg/L

Concentration of nitrates above 45 mg/L causes a diseases called as blue baby disease

Dissolved Gases

Methane explosiveH2S Bad smellCO2Indicates biological level then it indicates presence of organic matter oxygen deficiency 58 ppmMinimum Dissolved oxygen foe survival fishes etc = 4 mg/L


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BOD, COD, TOC, etc: BOD5= Loss of oxygen (mg/L) dilution factor BOD of safe drinking water = 0

Bacterial and Microscopic Characteristics

i) Aerobic Bacteria Required oxygen for survivalii) Anaerobic Bacteria Do not required dissolve O2iii)

Facultative Bacteria can survive with or without O2 Through some species of bacteria a may be helpful in cleaning of water but other

pathogenic bacteria are harmful

The presence of pathogenic bacteria can be tested by counting presence of coil Forms

ColiForms Also called B coli)

Coliforms are important harmless aerobic microorganism which are found residing in the

intestines of all warm blooded animals including human being Since these harmless organism live longer in water than the pathogenic bacteria it is

generally presumed that the water will be safe are free from pathogens if no coliformbacteria are present in it.

Measurement of coliform

Widely used

Filter the water through a sterile membrane of special design porosity = 80 pore size (5

to 10 rm) and the membrane is put in contact with nutrients (M Endos medium) thatwill permit the growth of only coliform colonies. This process is called culturing.

After an incubation period of 20 hrs, the coliform organs are developed into visible

colonies which can be easily counted Ecoli ferment lactose with gas formation with 48hours incubation at 350 C. Based on this E.coli density is estimated by multiple

fermentation procedure in different test. Which consist of identification of E.coli indifferent dilution combinations.

MPN value is calculation as followsFive 10 ml (five dilution combinations) tube is tested for E.coli and if out 5 only one given

positive test for E.coli and all other are negative

The from the table we can find out the MNP value for one (+ve) and other (-ve), which is

equal to 2.2 in present case

Coliform

Used to measure the coliform bacteria present in water sample

It may be defined as the reciprocal of the smallest quantity of a sample which would give apositive Bcoli test

Water Borne Diseases and Their Control

a) Disease caused by Bacterial infectionsDisease caused byi)

Typhoid fever - salmonella typhi

ii)

Cholera - vibro choleraiii) Bacillary Dysentery shiga bacillus or Flexner - bacillus

b)

Disease cause by viral infectionsi)

Hepatitis - Hepatist viral


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ii) Poliomyelitis - polio virus

c)

Disease caused by protozoal infectionsi)

Amoebic Dysentry Antoneoba histolitric germ

Quality Standard for Industrial Water Supply

Boiledferrd waterHardness 1 mg/L

Pulp and paper:L water should be free from iron Mn and hardness.

Quality Standard for Municipal Water Supply

Municipal water required for domestic uses, particularly the water required for drinking, mustbe colorless odourless and tasteless. It should be free turbidity and excessive toxic chemical and

bacteriological characteristics of water must be in between the desirable and permissible limit.

Basic Unit Process and Operation for Water Treatment.

Unit Process Aeration Function Removal) colour. Odour, taste.

Screening Floating matter

Chemical methods Iron, Mangness

Softening Hardness

Sedimentation Suspended matter

Coagulation Suspended matter, a part of colloidal water

and bacteria

Filtration Remaining colloidal, dissolved matter,bacteria

Disinfecting Pathogenic bacteria, organic and reducingsubstances.

Source Treatment required

1.

Ground water and spring waterfairly free from contamination

2.

Ground water with chemical,

mineral and gases3. Lakes, surface water reservoir,

with less amount of pollution4.

Other surface water such as river,

canals and impounded reservoir

with a considerable amount of

pollution

No treatment or chlorination

Aeration, coagulation (if necessary,filtration and disinfection)

Disinfection

Complete treatment


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