Chapter 2 Water Demand.pdf
Transcript of Chapter 2 Water Demand.pdf
-
8/12/2019 Chapter 2 Water Demand.pdf
1/15
Environmental Engineering(VCB 3033)
Water demand
and overview of
water treatmentplant
AP Dr. AmirhosseinMalakahmadCivil Engineering DepartmentUniversiti Teknologi PETRONAS
CO1: To identify thesources of water and itsimpurities and to performcomplex design of watertreatment plant to meetthe standard limits.
-
8/12/2019 Chapter 2 Water Demand.pdf
2/15
Unit Objectives
At the end of this session you will be able to:
Estimate the water demand and waterusage rate.
Forecast the population growth rate for
future developments.
Outline the water treatment plant unitprocesses.
-
8/12/2019 Chapter 2 Water Demand.pdf
3/15
-
8/12/2019 Chapter 2 Water Demand.pdf
4/15
Demand factor range
-
8/12/2019 Chapter 2 Water Demand.pdf
5/15
Example1: Using Historical Records to Estimate DemandFactors and Household Water Usage Rate
For a small water treatment plant, estimate the
following, using data gathered from the annual
water reports:
Maximum and minimum day demand factors.
Average household usage rate.
The average residential water usage is approximately 101 gpd/household.
So it appears this community is averaging approximately 1.5 individuals per
household. Give your opinions on how to tackle this matter.
-
8/12/2019 Chapter 2 Water Demand.pdf
6/15
Estimation of water demand
Total water demand of acommunity will comprise ofpublic, domestic, industrial,and commercial demand.
Q= Total quantity of water
requiredP= population
q= rate of demand(consumption) per capita/ day
Q= P q 365
-
8/12/2019 Chapter 2 Water Demand.pdf
7/15
A population equivalentis a method of
converting the water use (or wastewatergeneration) of commercial or industrial
users into the equivalent amount of water
used by a population number. For example,
an industrial unit may use the waterequivalent of 150 people in a residential
area. The projected equivalent population
(real population plus population
equivalents) is estimated to determine thefuture water demand.
-
8/12/2019 Chapter 2 Water Demand.pdf
8/15
Population design
Before a water supply system can bedesigned, it is necessary to determine thewater amount need to be served to
present and future population.This requires not only the design period
but also a population estimation (forecast).
To approach population estimation
appropriately, information on economicbasis, trade territory and, industrialexpansion plans of the city are essential.
-
8/12/2019 Chapter 2 Water Demand.pdf
9/15
Arithmetic method
This method is based on constant growth rate. This method is applicable if the projection period is
relatively short ( 5-10 years) and social and economic
activities in the area do not change drastically.
Pn= future population
P= present populationia= constant growth rate per decade
n = duration over which the projection is made, decade
Pn= P + nia
-
8/12/2019 Chapter 2 Water Demand.pdf
10/15
Example 2:Given that the population of a townin 1990, 2000, and 2010 are 90 000, 100 000,
110 500, respectively. Estimate the population
in 2020 using the arithmetic method.
-
8/12/2019 Chapter 2 Water Demand.pdf
11/15
Geometric method
This method is based on growth rate proportional topopulation size.
This method is applicable to growing towns and cities,where economic activities are growing and large landareas are still available for development or there is
unlimited scope of expansion.
Pn= future population
P= present population
ig= % increment of population
n= duration over which the projection is made, decade
Pn= P (1 + ig/100)n
-
8/12/2019 Chapter 2 Water Demand.pdf
12/15
Example 3:Population of a town in 2014 is
67,300 while it was 33,300 in 1990.
i. Estimate the population in 2040 using the
geometric method.
ii. Compare the annual water demand at
present and in 2040 if per capita water
demand to be 280 L/capita.day. Explain
your comparison.
-
8/12/2019 Chapter 2 Water Demand.pdf
13/15
Overview of water treatment process
Typical water treatment unit processes and their arrangement, These processes are
typically used for: (a) treatment of surface water and (b) treatment of water with high
levels of dissolved constituents.
-
8/12/2019 Chapter 2 Water Demand.pdf
14/15
Treatment of surface waters mostly requires theremoval of particulate matter and pathogens.Removing particles also assists in pathogen removal,because most pathogens either are particles or areassociated with particles.
If the water source contains dissolved constituents,then additional unit processes can be added toremove them as well.
Treatment of water with high levels of dissolvedconstituents will become more important in the futureas increases in population and demand, along withclimate change, force society to search for waters ofpoorer quality. These sources are sometimes high inTDS and are present as brackish ground- water,seawater, and reclaimed water.
Overview of water treatment process
-
8/12/2019 Chapter 2 Water Demand.pdf
15/15
Unit processes that remove a significant
amount of raw-water constituents