Environmental Engineering for
Civil Engineering By
www.thegateacademy.com
Syllabus
Environmental Engineering
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
2013
8.00
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
Overall Percentage
13.36%
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Contents
Environmental Engineering
CONTENTS #1
#2
Chapter Quality Standards of Water
Municipal Water Water Quality & Standard Hardness Basic Unit Process for Water Treatment Assignment 1
Page No. 1 – 12 1 1–2 2–5 5 6–7
Assignment 2 Answer Keys Explanations
7–9 10 10 – 12
Water Supply and Its Treatment
#3
Water Quality Standards for Drinking Water Water Requirements and Demands Population Forecast Basic Unit Process/Operation for Surface Water Treatment Screening Plain Sedimentation Electrical Properties Types of Sedimentation Tank Filtration Disinfection Solved Examples Assignment 1 Assignment 2 Answer Keys Explanations
Waste Water Treatment
Sewage & Sewerage Treatment Quality and Characteristic of Waste Water Types of Tracking Filters Secondary Sedimentation Solved Examples
13 – 53 13 14 – 16 16 – 19 19 – 20 20 20 – 23 23 – 25 25 – 26 26 – 30 30 – 37 38 – 44 45 – 47 47 – 49 50 50 - 53 54 – 90 54 54 – 72 72 – 73 73 – 74 75 – 84
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Contents
#4
Digestion and Disposal of Primary & Secondary Sludge Design Consideration Involved in An Activated Sludge Plant Effluent Disposal Solved Examples Assignment 1 Assignment 2
Answer Keys Explanations
#6
#7
Assignment 1 Assignment 2 Answer Keys Explanations
Sludge Disposal
#5
Environmental Engineering
Domestic Waste Water Treatment
85 – 86 87 – 88 89 89 – 90 91 – 110 91 – 96 96 – 98 98 – 99 100 – 103 104 – 105 106 – 107 108 108 – 110
Characteristic of Domestic Waste Water Treatment of Domestic Waste Water Chemical Treatment
111 – 122 111 – 112 112 – 113 113 – 114
Sludge Disposal Assignment 1 Assignment 2 Answer Keys Explanations
114 – 116 117 – 118 118 – 119 120 120 – 122
Air Pollution
Introduction Air Pollution System Zone of Atmosphere Monitoring of stack emissions
123 – 138 123 123 – 129 129 – 132 132 – 137
Filter Cleaning Method
137 – 138
Solid Waste
Classification fo Solid Waste Physical Properties of MSW (Municipal Solid Waste) Importance of waste transformation Sources of hazardous waste in MSW
139 –156 139 – 140 140 – 142 143 – 152 152 – 155
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Contents
Solved Examples
Module Test
Test Questions Answer Keys Explanations
Reference Book
Environmental Engineering
155 – 156 157 – 169 157 – 164 165 165 - 169 170
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Chapter 1
Environmental Engineering
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) ii) iii) iv) v)
Turbidity Colour Taste and odour Temperature 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
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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) ii) iii) iv) v) vi) vii)
pH Acidity Alkalinity Hardness Chlorides Iron solids 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 (due to presence of Carbonate and bicarbonate
permanent hardness (Due to presence of sulphates chlorides and nitrates.)
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Chapter 1
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) × = T.H =
Environmental Engineering
(mg|L) × (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 runoff 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 Minimum Dissolved oxygen foe survival fishes etc = 4 mg/L THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, info@thegateacademy.com © Copyright reserved. Web: www.thegateacademy.com Page 3
Chapter 1
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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 i) Hepatitis - Hepatist viral THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th Cross, 10th Main, Jayanagar 4th Block, Bangalore-11 : 080-65700750, info@thegateacademy.com © Copyright reserved. Web: www.thegateacademy.com Page 4
Chapter 1
Environmental Engineering
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 Remaining colloidal, dissolved matter, bacteria Pathogenic bacteria, organic and reducing substances.
Filtration Disinfecting
Source 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
Treatment required No treatment or chlorination Aeration, coagulation (if necessary, filtration and disinfection) Disinfection Complete treatment
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