1

SEM EXAM SHORT NOTES

ENVIRONMENTAL ENGINEERING MODULE 1
PER CAPITA DEMAND Chemical Characteristics of Treated Water
Defintion: It is the annual average amount of daily water required by one 1.pH: ranges from 6 to 8, preferably 7 and measured by litmus paper.
person and it includes domestic, industrial, commercial use. 2.Hardness: - caused by Ca2+, Mg2+ ion
denoted by "q". - Indicator is EBT and Titrant is EDTA
- two types, carbonate hardness & non carbonate hardness
3.Alkalinity: - Indicator is Phenolphthalein and Methyl orange
- Titrant is 0.02N H2SO4
4.Chlorinity: - Titrant is 0.0141N Silver Nitrate
- Indicator is Potassium Chromate
- desirable limit is from 250 mg/litre to 1000 mg/litre
Factors affecting Per Capita Demand 5.Nitrogen Content: - indicates the presence of organic matter
climatic conditions - present as ammonia, nitrate, nitrite, free NH3, etc
size of city 6.Metal and other chemical substances:
quality of water supply desirable limit of iron = 0.3 ppm
cost of water 7.Sulphate and Sulphide content:
industrial and commercial activities 8.Total Solids
habits of people 9.Biochemical oxygen Demand: measured in 5 days at 20 Celsius
type of gentry ie, APL or BPL 10.Chemical Oxygen Demand

Water borne diseases Turbidity

Cholera, Typhoid, Dysentry, Food poisoning, Diarrhoea. Definition: If a large amount of suspended matter such as clay, silt, and finely
Impurities present in water divided organic matter is present in water, it will appear to be
muddy or cloudy, this is called turbidity.
Suspended solids
It depends upon the fineness and concentration of particles.
Dissolved minerals (calcium, magnesium, and iron)
Expressed as mg/litre or ppm.
Organic matter (bacteria, algae, and plant debris)
Chemical pollutants (pesticides, heavy metals, and pharmaceuticals)
Methods for Determining Turbidity:
1. Nephelometry:
Scope of Environmental Causative Organism Measures the amount of scattered light by suspended particles in a sample.
Engineeering and Global Cholera - Vibrio cholerae A light source is directed into the sample.
Environmental Problems Typhoid - Salmonella typhi The scattered light at an angle to the incident light is measured using a
Dysentery - Shigella bacteria photodetector.
ozone layer depletion
Food poisoning - bacteria such as 2. Turbidimetry:
acid rain
Salmonella, E. Coli or toxins produced Measures the amount of light transmitted through a sample.
el nino
by Staphylococcus aureus A light source is directed through the sample.
global warming
Diarrhea - Various bacteria such as E. The intensity of light transmitted through the sample is measured using a
greenhouse effect
Coli or viruses like Norovirus photodetector.
severe drought and flood
3. Secchi Disk Method:
Types of Water Demand It is a visual method based on the depth at which a submerged disk
1.Domestic Water Demand - water required in residential buildings for becomes invisible.
domestic purposes. Lower a weighted disk (Secchi disk) into the water until it disappears from
Per Capita = 135 litre/head/day view.
Measure the depth at which the disk becomes invisible.
2.Industrial Water Demand - water demand of industry either existing
or ready to be started in future. Instruments Used to Determine Turbidity:
Ordinary Per Capita = 50 litre/head 1. Turbidity Rod
2. Turbidometer:
3.Institutional and Commercial Water Demand - water required for expressed as mg/litre or ppm
school, hospital, offices, etc. eg: Jackson’s turbidimeter(JTU), Baylis turbidimeter(BTU),
Nephelometer(NTU)
4.Public Use Demand - required for public utilities like gardening, In old instruments, light passed was observed while in newer ones the light
sprinkling of roads, etc. intensity is measured right angle to the incident ray.
Per Capita = 10 litre/head/day
IMPORTANCE OF BACTERIOLOGICAL TEST
5.Fire Demand - required for extinguishing fire. detects harmful microorganisms.
Min. water pressure available at the order of 100 to 150 kN/m^2 and Identifies pathogens that can cause waterborne diseases like cholera,
should be maintained for 4 to 5 hours. typhoid, and dysentery.
assess the effectiveness of water treatment processes.
6.Water required to compensate Losses + Theft Ensures water meets safety standards set by health authorities.

DESIGN PERIOD SIGNIFICANCE OF E.COLI IN WATER ANALYSIS

The future number of years for which provisions are made in Presence of E. coli indicates potential contamination by fecal matter.
designing the capacities of various components of a water supply Its presence suggests the possible presence of other harmful bacteria and
scheme. viruses.
Should not be too long (greater than 50 years). Regular testing for E. coli helps in ensuring the microbiological safety of
Should not be too short (example: 10 years). drinking water.
Minimum value is typically 30 years. Helps in assessing the risk of waterborne diseases and taking preventive
This 30-year period starts after the project completion. measures.
CAUSES AND EFFECTS OF ACID RAIN FACTORS AFFECTING POPULATION FORECAST
Causes: Fertility Rates
Sulfur Dioxide: From burning fossil fuels. Mortality Rates
Nitrogen Oxides: From vehicle exhaust and industrial processes. Migration Patterns: Influx or outflow of people to/from an area can
they form sulfuric and nitric acids in the atmosphere. significantly alter population forecasts.
Effects: Factors like economic conditions, education, and healthcare.
Acidifies water bodies, harming aquatic life.
Depletes nutrients, damaging forests.
PROBLEMS - AI, GI, II METHODS AND WATER SUPPLY PROBLEM
Corrodes buildings and worsens air quality - causing respiratory issues.

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 1

SEM EXAM SHORT NOTES

ENVIRONMENTAL ENGINEERING MODULE 2
PIPE APPURTANENCES FACTORS AFFECTING SELECTING LOCATION OF INTAKE
1. Gate Valves: Regulate water flow, often positioned at summits for Site should be near the treatment plant to reduce conveyance cost.
accessibility and cost-efficiency. located in the purer zone of the source so that best quality water is
2. Air Valves: Strategically placed along the pipeline to prevent withdrawn.
collapse or negative pressures, ensuring safety. never be located in the vicinity of wastewater disposal point.
3. Blow off or Drain Valves: Installed at low points to completely empty never be located near the navigation channels so as to reduce chances of
the pipeline for inspections or repair and maintanance pollution due to waste discharge from ships.
4. Pressure-relief Valves: release excess pressure, mitigating water located at a place from where it can draw water even during the driest
hammer pressures, and safeguarding joints from burst pipes. period.
5. Check Valves: Prevent backflow, ensuring one-way flow direction to easily accessible during floods and should not get flooded.
safeguard pumps and maintain system integrity and it Include swing should not be located on curves of meandering river.
check valves and foot valves, especially vital for maintaining suction.
6. Manholes: Positioned at intervals along pipelines (usually every 300 TYPES OF PUMPS
to 600 meters) for inspections and repairs.
7. Insulation Joints: Insulate pipelines from stray electric currents,
preventing electrolysis. Utilize rubber gaskets or coverings to
interrupt electric flow between pipe lengths.
8. Anchorages: Prevent pipes from pulling apart or slipping due to
unbalanced pressures or temperature changes. Made of concrete or
masonry, securely embedding pipe sections to control movement
and ensure joint integrity.

WORKING OF A CENTRIFUGAL PUMP

Principle/Use: It converts mechanical energy into pressure or hydraulic
1. Positive Displacement Pumps: Transfers fluid by trapping a fixed amount
energy by virtue of centrifugal force.
and forcing it into the discharge pipe.
Components: Impeller, Casing, Suction pipe, Foot valve and strainer,
2. Centrifugal Pumps: Utilizes centrifugal force to transfer fluid. Generally
Delivery pipe.
used for liquids with low viscosity. Suitable for high-flow, low-pressure
applications.
STEP 1: Generation of centrifugal force by rotation of impeller.
3. Axial Pumps: Utilizes rotating blades to move fluid along the axis of the
STEP 2: Suction and discharge through suction inlet and discharge outlet
pump. Commonly used in water jet propulsion systems for marine vessels.
by means of pressure variation.
4. Reciprocating Pumps: Operates using a back-and-forth motion of a piston
STEP 3: Conversion of kinetic energy to pressure energy, as fluid is
or diaphragm. Suitable for high-pressure applications.
propelled outward by impeller and passed through volute casing.
5. Rotary Pumps: Transfers fluid using a rotating mechanism. Suitable for
handling abrasive and high-viscosity fluids.
6. Single Rotor Pumps: Single rotor pumps utilize a single rotating element to
transfer fluid, making them suitable for applications such as lubrication
systems in machinery.
7. Multiple Rotor Pumps: Multiple rotor pumps employ multiple rotating
elements to transfer fluid efficiently, commonly used in high-pressure fuel
transfer systems for aircraft.
8. Diaphragm Pump: Diaphragm pumps utilize a flexible diaphragm to create
suction and discharge cycles, ideal for applications requiring precise
metering and handling of corrosive fluids in chemical processing.
SOURCES OF WATER 9. Piston Plunger Pump: Piston plunger pumps use reciprocating motion of a
1. Surface Source - Lakes, river, Shallow Well. piston within a cylinder to transfer fluid, often employed in high-pressure
2. Underground Source - Tubewell, Deepwell, Infiltration well, Springs. applications like hydraulic systems in heavy machinery.

REQUIREMENTS OF DISTRIBUTION SYSTEM FACTORS AFFECTING LOCATION OF PUMPING STATION

Water quality must not deteriorate within the distribution pipes. The location of the pumps should be above H.F.L.(Highest Flood level).
Capable of supplying water to all intended places with sufficient Required quantity of water should be available as the site.
pressure head. The pumping station should be at higher level above all the sources of
Ability to supply the required amount of water during firefighting contamination.
situations. The location site should be such that future growth and expansion may be
Layout should ensure that no consumer faces water shortage possible.
during repairs in any section of the system. The source of water should be permanent.
Distribution pipes should ideally be laid at least one meter away In case of meandering rivers, the site should be such that the water is
from or above sewer lines to prevent contamination. available at the pumping station
Distribution system should be fairly water-tight to minimize losses
DISINFECTION OF PIPELINE
due to leakage.
carried out to eliminate or reduce the concentration of harmful
INTAKE STRUCTURES microorganisms, ensuring the safety of the water supply.
They are structure that helps for safe withdrawal water from the involves the application of disinfectants such as chlorine or chloramine to
source and then to discharge this water in to the withdrawal conduit, the water flowing through the pipeline, effectively killing or inactivating
through which it reaches the water treatment plant. bacteria, viruses, and other pathogens present in the water.
DRY INTAKE WET INTAKE STORAGE OF WATER
water is absent inside the tower is filled with water upto Storage Reservoirs: Store treated water until it's pumped into distribution
tower when gates are closed. reservoir level. reservoirs, with a capacity of 14 to 16 hours of average daily flow.
affected by buoyant forces not affected by buoyant Distribution Reservoirs: serve to absorb hourly demand variations, reduce
when gates are closed. forces due to presence of costs by allowing constant pump operation, serve as emergency storage,
require heavy construction water. and maintain consistent pressure even in remote areas.
due to buoyant force. standard construction. Surface Reservoirs: Located at ground level or below, lined to prevent
water can be withdrawn from water withdrawal controlled leakage, and often positioned at high points for gravity flow.
any selected level by opening by gates on shaft. Elevated Reservoirs: Supported on towers, preferred for high-pressure
gate. withdrawn water maybe taken requirements, and made of materials like RCC or steel.
withdrawn water flows directly to pumphouse for lift.
through withdrawal conduit.

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SEM EXAM SHORT NOTES

ENVIRONMENTAL ENGINEERING MODULE 2
TYPES OF LAYOUTS OF DISTRIBUTION SYSTEMS 3. RING SYSTEM
1. DEAD END SYSTEM (TREE SYSTEM) Main pipe encircles the serviced area.
Simple tree-like structure: main pipe → submains → laterals. Continuous water flow without dead ends.
Water flows in one direction. Requires careful planning for coverage and pressure.
Easy and cheap to design. Reliance on a single ring may pose challenges.
Water supply disruption if faults occur. NB: Merits and Demerits are same as Grid Iron System
Stagnant water in dead ends, leading to wastage.
Merits: 4. RADIAL SYSTEM
Discharges and Pressures at different points can be easily and Divide the area into zones with central reservoirs.
accurately calculated. Water radiates outward from reservoirs to individual connections.
Requires lesser number of cut-off valves (sluice valves). Provides higher service heads and efficient distribution.
Shorter pipe lengths are needed and laying of pipes is easier. Requires significant infrastructure investment.
Cheap, simple, can be extended/expanded easily. Merit: Higher service heads, efficient distribution.
Demerits: Demerits: Infrastructure investment, may not be suitable for dense urban
Damage or repair in any pipeline completely stops water supply to that areas.
area.
Numerous dead ends that cause stagnation of water leads to
degradation of water quality.
Periodic removal of stale water at dead ends is required.
Greater wastage of treated water.
One directional supply only possible. Supplies for fire fighting cannot be
increased by diverting supplies from other side.

2. GRID SYSTEM (RETICULAR SYSTEM)

Network of interconnected pipes forming a grid pattern.
Water flows through multiple routes, eliminating dead ends.
METHOD OF DISTRIBUTION SYSTEMS
Complex design and requires larger pipes and more valves. 1. GRAVITATIONAL SYSTEM:
Suitable for well-planned urban areas. Water from a higher-level source flows naturally to lower-level
Merits: consumers due to gravity, without any pumping involved.
Since water reaches different places from different routes, the Suitable for cities situated at foothills with a water source at a higher
discharge, friction loss, and pipe size are reduced. elevation relative to the city.
During repairs very small area is affected. In this system, pumping is not required at any stage.
Dead ends are eliminated with interconnections. Water remains in
continuous circulation, which prevents stagnation.
During fire, more water can be diverted towards the affected area by
closing the cut off valves.
Demerits:
Requires more pipe length and large number of sluice valves (cut off
valves).
Costlier construction
Calculations for determing the pipe size, discharge, velocities and
pressures are tedious due to complex design.

2. PUMPING SYSTEM:
Uses high-lift pumps to pump water into mains at variable speeds to
meet varying demands.
Suitable for areas where continuous attention and variable water flow
are required, but power supply reliability is essential.
In this system, pumping is required to maintain a continuous water
supply, and complete stoppage of the water supply occurs during
power outages.

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SEM EXAM SHORT NOTES

ENVIRONMENTAL ENGINEERING MODULE 2
3. COMBINED GRAVITY AND PUMPING SYSTEM:
allows for storage and distribution of excess water during low-demand
periods.
Provides flexibility by combining pumping and gravity flow, with excess
water stored in the reservoir during low demand for supply during high
demand periods.
ensuring consistent water supply while utilizing stored water efficiently.

METHODS FOR DETECTING LEAKAGE IN WATER DISTRIBUTION

SYSTEM
(i) By direct observations:
Observe wet soft spots on unpaved ground or lush grass in a lawn.
Look for the emergence of springs in odd places, indicating
underground leakage.
May be challenging in sandy soils but can still provide preliminary
indications.
(ii) By using sounding rods:
Thrust a sharp metal rod along the pipeline and inspect for moisture or
mud.
Listen for the sound of escaping water by placing an ear on the rod.
Use instruments like aquaphones or sonoscopes to magnify leak
sounds, preferably during calm night hours.
(iii) By plotting the hydraulic gradient line:
Measure pressures at various points along the suspected pipeline.
Plot the hydraulic gradient line and look for kinks or changes in slope.
Identify leaks by observing deviations in the hydraulic gradient line,
indicating the location of a leak.
(iv) By using waste detecting meters:
Utilize specialized meters designed to detect water waste or abnormal
consumption patterns.
Monitor water flow rates and consumption levels to identify potential
leaks.
Employ data analysis techniques to pinpoint the location of leaks within
the distribution system.

FIRE HYDRANTS
Fire hydrants provide readily accessible points for firefighters to
connect hoses and access water in case of a fire emergency.
They facilitate the rapid deployment of water to extinguish fires, helping
to prevent the spread of fire and minimize property damage.

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