Water Use and Quality - Middle East Technical Universityusers.metu.edu.tr/bertug/SEES503/SEES 503 - 7 Warer Use and Qualit… · WATER USE AND QUALITY Uses of Water Consumptive use:

SEES 503 Sustainable Water Resources 1/93

Instructor

Assist. Prof. Dr. Bertuğ Akıntuğ

Civil Engineering ProgramMiddle East Technical University

Northern Cyprus Campus

SEES 503SEES 503SUSTAINABLE WATER RESOURCESSUSTAINABLE WATER RESOURCES

Water Use and QualityWater Use and Quality


7. WATER USE AND QUALITY 7. WATER USE AND QUALITY

Overview

Water Use CycleUses of WaterCategories of Water UseTrends in Water UseCategories of Water UseSustainable Water UseTrends on Water UseQuantities of Water

Characteristics of Municipal Water Supply SystemsWater QualityElements of Municipal Water Supply SystemDesign of Transmission Lines



Water Use Cycle

Water moves from a source to a point of use, and then to a point of disposition.

The sources of water are either surface water or groundwater.

Water is withdrawn and moved from a source to a point of use, such as an industry, restaurant, home, or farm.

After water is used, it must be disposed of (or sometimes, reused).

Used water is either directly returned to the environment or passes through a treatment processing plant before being returned.



Uses of Water

Domestic

Irrigation

Thermal Electric

Industry

Hydroelectric Electric

Municipal

Navigation

Wildlife

Recreation

Fish

WATER SUPPLY



Uses of Water

Source: http://geoscape.nrcan.gc.ca/h2o/bow/sharing_e.php



Uses of Water

Consumptive use: Some water is withdrawn from the river used and not returned.

Plant growth

Non-consumptive use: Some water is withdrawn from the river used and returned.

Hydropower generation, Recreation, Wildlife, Fisheries, Municipal water (90% returns back to water bodies as treated water)



Uses of Water

Source: http://geoscape.nrcan.gc.ca/h2o/bow/sharing_e.php

City of Calgary, Alberta, Canada



Uses of Water

CanadaSource: http://geoscape.nrcan.gc.ca/h2o/bowen/usage_e.php

USASource: http://www.snwa.com/html/cons_waterfacts.html



Uses of Water

Texas, USASource: http://www.utrwd.com/WaterConservation.htm

Winnipeg, Manitoba, CanadaSource: http://www.winnipeg.ca/waterandwaste/water/conservation/



Use of Water

Water use in the world 2005.Source: http://www.climate.org/topics/water.html



Uses of Water

Saline water use: Thermoelectric (98% in USA), Ex: for cooling generators in thermoelectric power plants.industrial, and mining (4% in USA).Ex: to cool machinery and to wash and transport products.

Saline water is a general term for water that contains a significant concentration of dissolved salts (NaCl).

Saline water concentration: (ppm: particle per million)Fresh water contains less than 1 g/lt (1000 ppm)Slightly saline water contains around 1-3 g/lt (1000-3000 ppm)Moderately saline water contains roughly 3-10 g/lt. (3000-10000 ppm)Highly saline water has around 10-35 g/lt. (10000-35000 ppm)Seawater has a salinity of roughly 35 g/lt. (35000 ppm)



Categories of Water Use

Commercial water use: fresh water for motels, hotels, restaurants, office buildings, other commercial facilities, and civilian and military institutions.

Domestic water use:water that is used in the home every day, including water for normal household purposes, such as

drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens.




Industrial water use:processing, cleaning, transportation, dilution, and cooling in manufacturing facilities. Major water-using industries: steel, chemical, paper, and petroleum refining.Industries often reuse the same water over and over for more than one purpose.

Irrigation water use:water that is used in the farm for crops,




Livestock water usewater for stock animals, feed lots, dairies, fish farms, and other nonfarm needs.Water is needed for the production of red meat, poultry, eggs, milk, and wool, and for horses, rabbits, and pets. Livestock water use only includes fresh water.

Mining water use:water for the extraction of naturally occurring minerals; solids, such as coal and ores; liquids, such as crude petroleum; and gases, such as natural gas. The category includes quarrying, milling (such as crushing, screening, washing, and flotation), and other operations as part of mining activity. A significant portion of the water used for mining, about 32 percent, is saline.




Public Supply water use:water withdrawn by public and private water suppliers, such as county and municipal water works, and delivered to users for domestic, commercial, and industrial purposes.

Thermoelectric Power water use:water used in the production of electric power generated with heat.



Sustainable Water Use

Local authorities can play a pivotal role in encouraging sustainable water use:

Reuse of water from sink and shower for toiletsReducing leakage problems of distribution networks and pipelinesUsing storm water (rain water) for your plants.Using water efficient toilets

1.6 gallons/flush



Trends on Water Use

Regional scale,

National scale, and

Global scale



Trends on Water Use

Source: http://ga.water.usgs.gov/edu/salineuses.html

Trend in water use in USA 1950-2000

Source: http://ga.water.usgs.gov/edu/totrendbar.html



Trends on Water Use

Source: http://ga.water.usgs.gov/edu/totrendbar.html

Trend in water use in USA 1950-2000



Trends on Water Use




Trends on Water Use




Trends on Water Use




Trends on Water Use

Source: http://www.eea.europa.eu/data-and-maps/figures/trends-in-european-water-use

Trends in European Water Use, 1990-2002



Quantities of Water

Source: http://www.climate.org/topics/water.html



Quantities of Water

Source: http://en.wikipedia.org/wiki/Water_resources



Quantities of Water

Water Quantity EstimationWater-use trends established over the past, provide some basis for estimating future water demands.The quantity of water required for municipal uses for which the water supply scheme has to be designed requires:

Water consumption rate,(Per Capita Demand in litres per day per head) andPopulation to be served.

(Water Quantity) = (Per capita demand) x (Population)



Quantities of Water

Water Consumption RateThere are many variable factors affecting water consumption.

It is very difficult to precisely assess the quantity of water demanded by the public.

The various types of water demands, which a city may have, may be broken into following classes:

Domestic Consumption (65-300 lit/capita/day)Industrial and Commercial Demand (45-450 lit/capita/day)Public Uses including Fire Demand (20-90 lit/capita/day)Losses and Waste (45-150 lit/capita/day)



Quantities of Water

Factors Affecting per Capita DemandSize of the city (characteristics of population and its size).Presence of industries. Climatic conditions. Habits of people and their economic status (living standards).Water quality.Pressure in the distribution system. Efficiency of water works administration: Leaks in water mains and services; and unauthorized use of water can be kept to a minimumby surveys. Cost of water. Policy of metering and charging method.


7. WATER USE AND QUALITY 7. WATER USE AND QUALITY Characteristics of

Municipal Water Supply Systems

The water demand should be estimated so that the system to be designed could meet these variations under all circumstances.

The design of a municipal water supply system is initiated bythe estimation of projected population, andthe investigation of water resources of desired quality and quantity.

According to the physical, chemical, and biological characteristics of water, a water treatment plant is required.

The construction of the distribution network within the city is undertaken by the municipality.




Water loss depends on thetype,age, andoperating pressures of the system.

Leakage must be minimized in the water supply system byproper design,proper construction, andusing suitable pipe material.

Care must be taken to minimize the hydraulic losses (friction and local losses).




Municipal Water RequirementsMunicipal water demand is the combination of requirements for

domestic,public,commercial and industrial use, andfire fighting.

Domestic Use:Domestic use includes the water demand for drinking and sanitarypurposes.The domestic use is affected by population size and living standards.Therefore, it is usually expressed as water demand on a per capita.In developed counties, domestic water demand is around 1000 lt/cap/day.




Municipal Water Requirements (con’t)Public Use:

The water requirement for public establishments, schools, hospitals, parks, etc.Water use in public establishments is normally required within certain hours during a day.Therefore, public use is generally lower than domestic use.

Commercial and Industrial Use:Water is required in the production of most industrial goods.

For example: 250 m3 of water is required to produce 1 ton of paper.

Fire Fighting Use:Sufficient quantity of water must be available in the distribution reservoirs for fire fighting.




Municipal Water Requirements (con’t)Water supply systems are designed to meet total projected municipal demand.

Step 1: The estimation of the lifetime of the system by considering the type of the system,the desired degree of hydraulic conformity,availability of technology,materials,appurtenances, andeconomy.




Municipal Water Requirements (con’t)

Step 2: The estimation of the projected water requirementcorresponding to the end of the lifetime of the system.

Normally based on the previous records concerning the estimation for the population and growth rates in the city understudy.

In the design of municipal water supply systems, theprojected population (Pn) of the community at the end of the lifetime of the project (tn) is to be estimated.




Municipal Water Requirements (con’t)Topographic and climatic conditions of the community and the socio-economic facilities available in the city may affect the rate ofmigration, and hence the population growth.

Before selecting the suitable method for the population estimation, the past records of census results and the socio-economic development in the region should be investigated.

According to the nature of the rate of population growth and characteristics of the community, the best method can be selected from following methods.




Municipal Water Requirements (con’t)1. The Arithmetic Extrapolation Method

This method can be used if the population growth rate of the community is observed as constant.In this method

in which Ka: constant

where P1 and P2 : the populations of the community at year t1 and t2, respectively.

The projected population (Pn) :




Municipal Water Requirements (con’t)2. The Geometric Extrapolation Method

This method is considered for communities having large resourcesand power. This method is used by the Turkish State Institute of Statistics.In this method

in which Kg: constant

where P1 and P2 : the populations of the community at year t1 and t2, respectively.





Municipal Water Requirements (con’t)3. The Turkish Bank of Provinces Method

This method which is an alternative form of the geometric extrapolation is also used in Turkey.The projected population (Pn) :

in which k is

where n: the number of years between the last census and the beginning of the project.k: growth rate factor. k=3 if k≥3, k=1 if k≤1, and k is as it is if 1<k<3.




Municipal Water Requirements (con’t)4. Logistic S-curve Method

The growth of communities with limited land area for future growth can be modeled by this method.This method combines a geometric growth rate at low population with a declining growth rate as the city approaches a saturationpopulation.The projected population (Pn) :

where Psat is the saturation population and a and b are constants as

where n: the time interval between two successive censuses.P0, P1, and P2 are the populations measured during the last three consecutive

censuses.




Municipal Water Requirements (con’t)5. Declining Growth Rate Method

In this method, the rate of change of population is given as

in which Kd is




Characteristics of Municipal Water Supply Systems

Example: Estimate the projected population of Eskisehir, Turkey for the year 2010 using the following methods:a) Arithmetic extrapolationb) Geometric extrapolationc) Bank of Provinces d) Logistic S-curve e) Declining growth rate

706009641301543802495097459367415101368827323511276164244251Population

2000199019801975197019651960195519501945Year




Municipal Water Requirements (con’t)The next step beyond the determination of the projected population is to estimate the average total demand corresponding to the projection year.

However, this is relatively difficult because of high degree of uncertainty inthe development trends, and population growths.

As preliminary information Table 7.1 can be used.Table 7.1 reflects the average water consumption for Middle Eastern countries.




Fluctuations in Water UseThe use of water in a community exhibits hourly, daily, and monthly variations depending upon

the climatic conditions,size of the urban area, andsocio-economical structure of the community.




Fluctuations in Water UseFluctuations in water use are quantified for the design of various components of water supply systems.They are expressed in terms of hourly, daily, and monthly peak factors as

whereDmh: The max. hourly demand during a day,Dah: The av. hourly demand in that day,Dmd: The max. daily demand during a year,Dad: The av. daily demand in that year,Dmm: The max. monthly demand during a year,Dam: The av. monthly demand in that year,



Characteristics of Municipal Water Supply Systems

Example: The average monthly supplies of a river in 106 m3 are given below together with the demand variation factors (DVF). This river supplies the demands of a city with the populations P1995=460,000 P2000=500,000. Using the method of geometric extrapolation, determine

a) until when the river can supply the demand of the city; andb) until when the river can supply the demands of the city by 100% regulation.

0.920.90.961.081.181.251.131.00.870.890.920.9DVF

1110121189172131171214Q x 106

DecNovOctSepAugJulJunMayAprMarFebJanMonth



Water Quality

Water resources are subject to continuous pollution due to the entrainment of some contaminants to waters from the atmosphere, ground surface or subsurface in the form of suspended particles or dissolved substances like

Ca (calcium)Mg (magnesium)Mn (manganese)N (nitrogen)CO2 (carbon dioxide)

Some bacteria, which are present in the atmosphere, may be captured by rain or snow droplets.Some of the heavy metals like Pb (plumbum), Cu (copper), Zn (zinc), and Fe (iron) may be added to the pipe flow as a result of pipe corrosion.



Water Quality

Water treatment is essential to maintain hygienic conditions because water may transmit some communicable diseases, which are of

bacterial origin (typhoid, dysentery, cholera, etc.)viral origin (hepatitis),protozoal origin.

Special care must be taken to preserve the water supply system against the intrusion of waste water.

Water quality management practices of reservoirs should be basedon the control of the quality parameters in the vertical directionsuch that water is to be withdrawn from the desired elevation.



Water Quality

A water intake tower, which provides multi-level withdrawal capacities, may be suitably utilized for this puropse.The deficiencies in the operation of awater supply system may affect the hygienic conditions adversely in the system.

For example: As a result of a sub-atmospheric pressure in the pipes during the periods of water shortage, polluted water may enter into the pipes from the joints.

Continuous monitoring of the water quality parameters in the distribution network should be carried out.Disinfection may be needed in the network.



Water Quality

Source: http://www.geograph.org.uk/photo/754213 Source: http://www.sweetwaterfishing.com.au/Monduran.htm

Water Intake Tower:



Water Quality

Pumping Station:

Source: http://www.ci.brenham.tx.us/WaterTreatment.cfm



Water Quality

Principal Characteristics of WaterThe presence of impurities in water, which may originate from

the soil, atmosphere, decomposition of organic matter, living organisms, and municipal and industrial sources etc.

may characterize the quality of water.

In this course, only the fundamentals of drinking water quality requirements and water treatment techniques are discussed briefly.

Physical, chemical, and biological characteristics of water must be tested periodically. (Testing methods are out of the scope of this course)



Water Quality

Principal Characteristics of Water (con’t)Physical Properties of Water

Total solids may range in size from suspended sediments to tree branches.Turbidity is the term used to express the clarity of water due to colloidal particles of clay or silt and microorganisms.

Surface waters have usually higher turbidity than groundwater.Color, taste, and odor are aesthetic properties of water that are caused by dissolved and colloidal organic matter or decaying vegetation.Temperature is an important property for assessing the effects of water on living organisms.

Chemical Properties of WaterpH is a measure of the concentration of hydrogen ions (H+) and indicates the degree of acidity or basicity (alkalinity of water to neutralize acids) of the water.

0<pH<14. pH=7 natural water. (Natural water: 6.0 ≤pH≤8.6)pH<7 the water is acidic having sourish taste.pH>7 the water is alkaline having bitterish taste.



Water Quality

Principal Characteristics of Water (con’t)Chemical Properties of Water (con’t)

Electrical conductivity is a property indicating the presence of dissolved salts.Dissolved oxygen, (DO) is an essential ingredients for the sustenance of all forms of aquatic life.

A high concentration of DO, which may improve the taste, can be achieved through aeration operation in the treatment plant.

Biochemical oxygen demand (BOD) is a measurement of the consumption of oxygen by microorganisms in the oxidation of organic matter.

A high value of BOD indicates greater concentration of organic matter originating from wastewater.

Nitrogen indicates the state of pollution by organic wastes with larger quantities in the nitrate form, and this indicates oxidation.Chlorides indicates the presence of seawater with NaCl or sewage pollution from other chloride compounds.

The presence of high concentrations of NaCl increases corrosion.



Water Quality

Principal Characteristics of Water (con’t)Chemical Properties of Water (con’t)

Hardness is a measure of soap consuming capacity and it may be temporary or permanent depending on the chemical composition.

Hardness of groundwater is higher than that of surface water (minerals in aquifers).Temporary hardness may be improved by boiling the water.Special chemicals are required to soften permanent hardness.If hardness of water > 150 mg/lt, use of it is not economical since it increases the soap consumption.

Biological Properties of WaterWater supplies to be utilized for domestic use must be examined for bacteriological composition.The possibility of pathogenic disease may be assessed by determining the number of coliform bacteria. Presence of coliforms beyond a certain limit is a proof of some waterborndiseases.



Water Quality

Drinking Water Quality RequirementsDrinking water quality guidelines given by WHO (World Health Organization) and TS 266.

Water quality requirements vary considerably according to the purpose of water use.

very poisonous

may change odor, taste and color



Water Quality

Drinking Water Quality RequirementsThere are four classes of raw water depending upon the category of water resources and degree of treatment they require:

Class 1: High quality water requiring only filtration and disinfection.

Class 2: Slightly polluted water requiring a normal treatment process.

Class 3: Polluted water requiring intensive physical and chemical treatment.

Class 4: Highly polluted water requiring intensive physical and chemicaltreatment and advanced biological treatment.



Water Quality

Drinking Water Quality RequirementsIntensive care must be taken to preserve the water bodies to be utilized for municipal requirement and fish life.

In the absence of state regulations, the following rules might be applied:Recreational use should be permitted only when there is a real need for such use and the need cannot be supplied by other bodies of water.Use should be controlled by caretakers with police authority whose costs are paid by fees assessed against the recreational users of the lake.Picnic and camping should be restricted to areas with garbage and toilet facilities.Swimming and other water-contact sports should be restricted to areas at least 2 km distant from the intake.Noncontact recreation, such as fishing, boating, and hunting should be restricted to areas at least 200 m from the intake.Any residential development within the drainage area should be provided with sewage treatment adequate to ensure protection of the resources.



Water Quality

Water Treatment MethodsWater bodied to be utilized for municipal requirements must be

analyzed from the quality viewpoint and classified according to the criteria described in the previous section.

1. Physical Treatment MethodsScreening is the process of removing large floating and suspended debris from water.

Aeration is the process of subjecting the collected waterto air for the addition of oxygen to

oxidize dissolved Fe and Mn, removal of CO2, and removal of hydrogen sulfate (H2S) to eliminate odor.



Water Quality

Water Treatment Methods1. Physical Treatment Methods (con’t)

Mixing is the process through which rotating paddlesin mixing chambers facilitate a high degree of dispersion of chemicals e.g. chlorine, ozone, KMnO4, which areadded to collected water for treatment.

Flocculation is the process in which small suspendedparticles having different sizes collide with each otherby mixing and form fewer, but larger particles, whicheasily settle.

Sedimentation facilitates favorable conditions so that the suspended silt, sand, and heavy minerals in water can settle down.



Water Quality

Water Treatment Methods1. Physical Treatment Methods (con’t)

Filtration is the process during which water passes through a sand bed, preferably composed of quartz sand because of its resistance against abrasion.

Through the filtration process, odor, taste, and turbidity are improved.

2. Chemical Treatment MethodsCoagulation is the process to initiate flocculation in which fine suspended particles or colloids are flocculated by means of chemicals called coagulants such as aluminum sulphate and iron tri-chloride.

Disinfection, which is the killing of disease causing bacteria, may be simply achieved by boiling water.

For intensive disinfection mainly chlorine, ozone, or UV radiation may be used against pathogenic bacteria.



Water Quality

Water Treatment Methods2. Chemical Treatment Methods (con’t)

Chlorination is the most effective and economical disinfection, which is commonly formed in three step:

Pre-chlorination is the addition of chlorine at the entrance of treatment plant prior to any treatment.The second phase of chlorination is the addition of chlorine through mixing operation.Post-chlorination is the addition of chlorine subsequent to filtration.

Water softening by precipitation, which is accomplished by removing iron and manganese, is needed to reduce the hardness .

It requires addition of Ca(OH)2 (lime) and Na2CO3 (soda ash).



Water Quality

Water Treatment Methods2. Chemical Treatment Methods (con’t)

Water softening by ion exchange is accomplished as the hard water having high concentrations of calcium and magnesium passes through the ion exchange bed where calcium and magnesium in water are exchange for sodium (soft water) in the medium.

Odor and taste control are performed by adding copper sulphate and active carbonic ash to water to prevent the growth of algae since it may produce toxins, which cause human illness.

3. Biological Treatment MethodsNormally applicable to the worst quality waters having excessive microorganisms with pathogenic origins.


7. WATER USE AND QUALITY 7. WATER USE AND QUALITY Elements of Municipal Water Supply

System

Water is conveyed from a source or combination of sources to community in mainly closed conduits.

pressurized flow is possiblepollution control

Possible element of a water transmission system:canals and flumesgrade aqueductsgrade tunnelspipelinesvalvespumpspressure reducing chambers etc….

1915-19 Winnipeg, Manitoba, Canadahttp://www.mhs.mb.ca/docs/pageant/24/winnipegaqueduct.shtml



System

Transmission pipelineshttp://www.wau.boku.ac.at/fileadmin/_/H81/H811/Skripten/811356/05_Supply_Storage_distribution.pdf



System

Typical arrangement of a municipal water supply system

Distribution reservoirs are designed to meet the hourly variations in water demand and to store extra water for fire fighting and emergencies.



System

In the main transmission line Qdesign= Dmd = Dad x (P.F.)day

In a main feeder Qdesign= Dmh = Dmd x (P.F.)hour

OR

Qdesign= Dmh = Dad x (P.F.)hour x (P.F.)day



System

A water distribution network is normally composed of pipes, valves, hydrants, and pumps.

Distribution of water is possible bygravity (storage reservoir is required at a sufficient altitude)pump without storage (may be required during any emergency), andpump with storage (the most common way).



System

Distribution ReservoirsIn large cities (population > 100,000) pumping stations and distribution reservoirs are operated in conjunction with each other.Pumping stations usually pump the average daily demand to distribution reservoirs during the minimum demand hours of the day.Distribution reservoir release the water when the demand is above the average daily demand to meet the fluctuations in use.Location: as close as the center of use as possible.Water Level: high enough to permit gravity flow at satisfactory pressure.



System

Distribution Reservoirs (con’t)May be located in critical points in the city in such a way that the hydraulic grade line is still above the highest storey buildings.Elevated tanks: circular cross-section (cylinder gives a max. volume).Buried reservoirs: rectangular

cross-section (easy to construct)Small: concrete or stone masonryLarge: reinforced concrete with dividing walls

Cylindrical Reservoirs: reinforces concrete or steel



System

Distribution Reservoirs (con’t)Elevated tanks: circular cross-section (cylinder gives a max. volume).

Source: http://www.wilsonnc.org/departments/publicservices/watertreatment/elevatedwatertanks/



System

Distribution Reservoirs (con’t)Elevated tanks: circular cross-section (cylinder gives a max. volume).



System

Distribution Reservoirs (con’t)A fill layer of about one meter thick is placed.Lower temperature in summer (better quality and taste)

Buried distribution reservoirhttp://www.wau.boku.ac.at/fileadmin/_/H81/H811/Skripten/811356/05_Supply_Storage_distribution.pdf



System

Distribution Reservoirs (con’t)




System

Distribution Reservoirs (con’t)




System

Distribution Reservoirs (con’t)The capacity of a distribution reservoir is determined by the summation of the following components:

Storage to meet hourly fluctuations,Required storage to put out a fire with certain duration (Cfire)Storage to meet emergencies



System

PipesPipes materials:

reinforced concrete (no corrosion problem),asbestos cement (limited use cancerous effect of asbestos fibers),ductile iron (corrosion problem interior is coated with cement),steel (good for large diameter and high pressure, buckling under high negative pressure)plastic (widely used, highly smooth, light, easy to install and remove)

The minimum pipe size required in a distribution network is dictated by the population.



System

PumpsPumps: mechanical energy potential energyTypes of pumps are named according to the direction of the movement of water from the rotating element of the pump (impeller).The specific speed:

where Q: discharge (m3/s)N: rotative speed of impeller (rpm)Hp: Head (m)

2/3p

sHQN

n =



System

Pumps (con’t)Centrifugal Pumps:

For the requirement of high heads (low ns).Impeller in series having radial flow characteristics are adopted.

Axial-flow Pumps:For greater flow rates under low heads (high ns).Having axial flow characteristics with respect to the pump axis.

Mixed-flow Pumps:For medium head and discharge (medium ns).



System

Pumps (con’t)Centrifugal Pumps:

http://en.wikipedia.org/wiki/File:CetriFugal_Pump.jpg

http://www.thomasnet.com/articles/pumps-valves-accessories/centrifugal-principles



System

Pumps (con’t)Axial-flow Pumps:

http://en.wikipedia.org/wiki/File:Axial_2.png http://www.directindustry.com/prod/weir-minerals/axial-flow-pump-23306-376724.html



System

Pumps (con’t)Mixed-flow Pumps:

http://www.shakthipumps.com/download/mixed-flow-pumps.pdf

http://www.pattersonpumps.com/axial.html#



System

Pumps (con’t)Power of the pump:

where Pp: the power (kW).γ: specific weight of water (kN/m3)Q: discharge (m3/s)Hp: head of the system by the pump (m)ηp: the efficiency of the pump

p

pp

QHP

ηγ

=



System

Pumps (con’t)Multiple pump operations are often used to increase the discharge or head.

Pumps in Series: Increase the head

Pumps in Parallel: Increase in discharge



System

Valves Sluice or gate valves are used to isolate the flow especially during repair works.

http://en.wikipedia.org/wiki/Gate_valve



System

Valves Butterfly valves are widely used at the exits of distribution reservoirs for regulation or isolation purposes.

http://en.wikipedia.org/wiki/Butterfly_valvehttp://www.scanco.no/produkter_ventiler.php



System

Valves Check valves are used to stop flow automatically in the reverse direction.

http://www.checkall.com/valvestyles/un3/un3enlargedphoto.htm

http://www.spiraxsarco.com/resources/steam-engineering-tutorials/pipeline-ancillaries/check-valves.asp

http://www.checkvalves.co.uk/



System

Valves Hydrants are those appurtenances used for the withdrawal of pressurized flow from the network for fire fighting.

http://en.wikipedia.org/wiki/Fire_hydrant



Design of Transmission Lines

The pipe size should be determined to meet future requirements.

The system should confirm to the required hydraulic performance:velocity criteriapressure criteria etc…..

In this section design principles ofgravity lines,pumped lines, andmixed lined

are introduced.




Design of Gravity LinesFor a gravity pipeline, neglecting operating cost, the optimum diameter minimizes the capital cost of the pipeline.

The optimum diameter minimum diameter which can convey the specified design discharge with the available gravity head.

In gravity lines there are several design criterions:Velocity: 0.5 – 2.0 m/sPressure head: 3-5 m – 80 m




Design of Pumped LinesFor a pumped line, the economical diameter is the one which minimizes the total cost.

investment cost of pipes (placement and installation costs),cost of pump,energy cost of operation (operation and maintenance costs).

A small diameter reduces initial cost but increases pumping and energy costs.

Design is to find the most economical diameter.




Design of Mixed LinesA pipeline having both

gravitational and pumped flow rates.

Topographic elevation of point C is higher than the reservoir level.In such a case it is convenient to build a small reservoir at C.The pump may be

located at reservoir site A orlocated as a booster pump along the line.

Topographic elevation of point C is higher than the reservoir level.




Design of Mixed Lines (con’t)If the pump is located at reservoir site A, the economic pipe diameter can be computed considering line ABC as a pump discharge line

The diameter of line CD is then determined as a gravity pipeline.




Design of Mixed Lines (con’t)If a small diameter is used until the buster pump,

the initial cost will be lessthe energy cost will be high (the pump will be in at a lower elevation)

Note that for the booster pump applications the followings must also be considered:

cost of energy line transportation, andcost of employment of guards, etc…

Documents

Water Use and Quality - Middle East Technical Universityusers.metu.edu.tr/bertug/SEES503/SEES 503 - 7 Warer Use and Qualit… · WATER USE AND QUALITY Uses of Water Consumptive use: