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Environmental Engineering

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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

2009 12.00

2008 12.67

2007 14.67

2006 16.00

2005 13.33

2004 17.33

2003 18.00

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, [email protected] © Copyright reserved. Web: www.thegateacademy.com Page I

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


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




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


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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




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




120 120 – 122

#6 Air Pollution 123 – 138

Introduction Air Pollution System

123 123 – 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 Solid Waste)

140 – 142

Importance of waste transformation 143 – 152

Sources of hazardous waste in MSW 152 – 155


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Solved Examples 155 – 156

Module Test 157 – 169

Test Questions 157 – 164


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



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.)



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

Minimum Dissolved oxygen foe survival fishes etc = 4 mg/L



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



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 Complete treatment

gate material civil engineering, environmental engineering

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