Environmental Engineering
for
Civil Engineering
By
Syllabus Environmental Engineering
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Syllabus for Environmental Engineering
Quality standards, basic unit processes and operations for water treatment. Drinking water standards, water requirements, basic unit operations and unit processes for surface water treatment, distribution of water. Sewage and sewerage treatment, quantity and characteristics of wastewater 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 200912.00
200812.67
200714.67
200616.00
200513.33
200417.33
200318.00
Contents Environmental Engineering
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CONTENTS
Chapter
Page No.
#1
Quality Standards of Water
1 – 12
Municipal Water
1
Water Quality & Standard
1 – 2
Hardness
2 – 5
Basic Unit Process for Water Treatment
5
Assignment 1
6 – 7
Assignment 2
7 – 9
Answer Keys
Explanations
10
10 – 12
#2
Water Supply and Its Treatment
13 – 53
Water Quality Standards for Drinking Water
13
Water Requirements and Demands
14 – 16
Population Forecast
16 – 19
Basic Unit Process/Operation for Surface
Water Treatment
19 – 20
Screening
20
Plain Sedimentation
20 – 23
Electrical Properties
23 – 25
Types of Sedimentation Tank
25 – 26
Filtration
26 – 30
Disinfection
Solved Examples
30 – 37
38 – 44
Assignment 1
45 – 47
Assignment 2
47 – 49
Answer Keys
Explanations
50
50 - 53
#3
Waste Water Treatment
54 – 90
Sewage & Sewerage Treatment
54
Quality and Characteristic of Waste Water
54 – 72
Types of Tracking Filters
72 – 73
Secondary Sedimentation
Solved Examples
73 – 74
75 – 84
Contents Environmental Engineering
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Assignment 1
85 – 86
Assignment 2
87 – 88
Answer Keys
Explanations
89
89 – 90
#4
Sludge Disposal
91 – 110
Digestion and Disposal of Primary &
Secondary Sludge
91 – 96
Design Consideration Involved in An Activated
Sludge Plant
96 – 98
Effluent Disposal
Solved Examples
98 – 99
100 – 103
Assignment 1
104 – 105
Assignment 2
106 – 107
Answer Keys
Explanations
108
108 – 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
Assignment 1
117 – 118
Assignment 2
118 – 119
Answer Keys
Explanations
120
120 – 122
#6
Air Pollution
123 – 138
Introduction
Air Pollution System
123
123 – 129
Zone of Atmosphere
129 – 132
Monitoring of stack emissions132 – 137
Filter Cleaning Method
137 – 138
#7
Solid Waste
139 –156
Classification fo Solid Waste139 – 140
Physical Properties of MSW (Municipal Solid Waste)140 – 142
Importance of waste transformation143 – 152
Contents Environmental Engineering
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Solved Examples155 – 156
Module Test
157 – 169
Test Questions
157 – 164
Answer Keys
Explanations
165
165 - 169
Reference Book
170
Chapter 1 Environmental Engineering
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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) Springs
ii) 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) Colour
iii) Taste and odour iv) Temperature
v) 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) Jackson’s 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
Chapter 1 Environmental Engineering
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Colour: Dissolved organic material from decaying vegetation or inorganic materials may import colour to the water.
The standard unit of color is that which is produce by “one mg of platinum cobalt” dissolved in one liter of distilled water
The 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: μmho/cm) Chemical characteristics i) pH ii) Acidity iii) Alkalinity iv) Hardness v) Chlorides vi) 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 CO2 mineral 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 with the 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 sulphates Carbonate and bicarbonate chlorides and nitrates.)
Chapter 1 Environmental Engineering
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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/L T.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 hardness if 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 of sulphides
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/L Permissible limit – 1.0 mg/L
Nitrates: 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 – explosive H2S – Bad smell
CO2 – Indicates biological level then it indicates presence of organic matter oxygen deficiency 5
– 8 ppm
Chapter 1 Environmental Engineering
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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 survival ii) Anaerobic Bacteria → Do not required dissolve O2
iii) 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 coliform bacteria 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 – Endo’s medium) that will 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 48 hours 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 in different dilution combinations.
MPN value is calculation as follows
Five 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 a positive B coli test”
Water Borne Diseases and Their Control a) Disease caused by Bacterial infections
Disease caused by
i) Typhoid fever - salmonella typhi ii) Cholera - vibro – cholera
iii) Bacillary Dysentery – shiga bacillus or Flexner - bacillus b) Disease cause by viral infections
Chapter 1 Environmental Engineering
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ii) Poliomyelitis - polio virus
c) Disease caused by protozoal infections
i) Amoebic Dysentry – Antoneoba histolitric germ
Quality Standard for Industrial Water Supply Boiledferrd water
Hardness 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, must be 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 reducing
substances.
Source Treatment required
1. Ground water and spring water fairly free from contamination 2. Ground water with chemical,
mineral and gases
3. Lakes, surface water reservoir, with less amount of pollution 4. 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
