Water treatment plants

66
Water Treatment Plants

description

 

Transcript of Water treatment plants

Page 1: Water treatment plants

Water Treatment Plants

Page 2: Water treatment plants

Water Treatment Plants 2

Thought Of The Day

Page 3: Water treatment plants

Water Treatment Plants 3

Water Flow

Page 4: Water treatment plants

Water Treatment Plants 4

Water Consumption

Water provided for human consumption requires treatment in order to make it• safe (potable)• pleasant to taste (palatable)

Modern technology offers remarkable capabilities to accomplish these goals• introduction of new and different pollutants• cost of treating to required levels is a

challenge for the water supply industry

Page 5: Water treatment plants

Water Treatment Plants 5

Water Demand

• Municipal  water supplies are treated to be both palatable and potable, regardless of their intended use

• If each person uses about 100 litres of water per day

• Commercial and industrial users may increase that demand by more than 5 times

Page 6: Water treatment plants

Water Treatment Plants 6

Drinking Water - Quality

Our water supply comes from two sources• surface waters i.e.

rivers, lakes and reservoirs

• groundwater, which is stored below the earth's surface

Each source presents its own problems

• Surface water has elevated levels of soil particles and algae, making the water turbid

• may contain pathogens

• Groundwater has higher levels of dissolved organic matter (yellow color) and minerals such as iron

• Both sources may have high levels of calcium and magnesium (hardness)

• both can be contaminated by toxic chemicals

Page 7: Water treatment plants

Water Treatment Plants 7

Water Treatment Process

Page 8: Water treatment plants

Water Treatment Plants 8

Drinking Water Plant

Page 9: Water treatment plants

Water Treatment Plants 9

Untreated to Treated Water

Page 10: Water treatment plants

Water Treatment Plants 10

Conventional Surface Water Treatment

Screening

Coagulation

Flocculation

Sedimentation

Filtration

Disinfection

Storage

Distribution

Raw water

AlumPolymers

Cl2

sludge

sludge

sludge

Page 11: Water treatment plants

Water Treatment Plants 11

Screening

• Removes large solidslogsbranchesragsfish

• Simple processmay incorporate a mechanized trash removal system

• Protects pumps and pipes in Water Treatment Plants

Page 12: Water treatment plants

Water Treatment Plants 12

Coagulation

• Small particles are not removed efficiently by sedimentation because they settle too slowly

• they may also pass through filters

• easier to remove if they are clumped together

• Coagulated to form larger particles, but they don't because they have a negative charge

• repel each other (like two north poles of a magnet)

• In coagulation• we add a chemical such

as alum which produces positive charges to neutralize the negative charges on the particles

• particles can stick together• forming larger particles • more easily removed• process involves addition of

chemical (e.g. alum) • rapid mixing to dissolve the

chemical• distribute it evenly

throughout water

Page 13: Water treatment plants

Water Treatment Plants 13

Coagulants

• Aluminum Sulfate Al2(SO4)3

• Ferrous Sulfate FeSO4

• Ferric Sulfate Fe2(SO4)3

• Ferric Chloride FeCl3• Lime Ca(OH)2

Aluminum salts are cheaper but iron salts are more effective over wider pH range

Factors for choosing a coagulant?1. Easily available in all

dry and liquid forms2. Economical 3. Effective over wide

range of pH4. Produces less sludges5. Less harmful for

environment6. Fast

Page 14: Water treatment plants

Water Treatment Plants 14

Flocculation• Now the particles have a

neutral charge• can stick together• The water flows into a tank

with paddles that provide slow mixing

• bring the small particles together to form larger particles called flocs

• Mixing is done quite slowly and gently in the flocculation step

• If the mixing is too fast, the flocs will break apart into small particles that are difficult to remove by sedimentation or filtration.

Page 15: Water treatment plants

Water Treatment Plants 15

Sedimentation• water flows to a tank called a

sedimentation basin• gravity causes the flocs to settle

to the bottom• Large particles settle more

rapidly than small particles• It would take a very long time for

all particles to settle out and that would mean we would need a very large sedimentation basin.

• So the clarified water, with most of the particles removed, moves on to the filtration step where the finer particles are removed

Page 16: Water treatment plants

Water Treatment Plants 16

Filtration• The filtration apparatus is a

concrete box which contains sand (which does the filtering), gravel (which keeps the sand from getting out) and underdrain (where the filtered water exits)

• After the filter is operated for a while, the sand becomes clogged with particles and must be backwashed

• Flow through the filter is reversed and the sand and particles are suspended

• The particles are lighter than the sand, so they rise up and are flushed from the system. When backwashing is complete, the sand settles down onto the gravel, flow is reversed and the process begins again

Page 17: Water treatment plants

Water Treatment Plants 17

Raw water

Coagulation

Aeration

Flocculation

Sedimentation Tank

Page 18: Water treatment plants

Water Treatment Plants 18

Page 19: Water treatment plants

Water Treatment Plants 19

Disinfection• With particles removed, it only

remains to provide disinfection, so that no pathogens remain in the water

• Protozoan pathogens are large in size and have been removed with other particles

• Bacteria and viruses are now destroyed by addition of a disinfectant

Chlorination• Enough chlorine is added so that

some remains to go out in the water distribution system, protecting the public once the water leaves the plant

Page 20: Water treatment plants

Water Treatment Plants 20

Softening• Areas where water comes into

contact with limestone, there may be high levels of calcium and magnesium present

• these chemicals make the water "hard"

• Hardness is removed by a process called softening

• Two chemicals (lime, CaO and soda ash, Na2CO3 ) are added to water

• causing the calcium and magnesium to form precipitates

• solid substance is then removed with the other particles by sedimentation and filtration

Page 21: Water treatment plants

Water Treatment Plants 21

Synthetic Organic Chemicals

• Water supplies can be contaminated with synthetic organic chemicals (SOCs) from agricultural runoff or commercial and industrial sources

• such as the leaking underground storage tank

• These chemicals are not efficiently removed by the simple water treatment process

• These chemicals can be removed by passing the water through a layer of activated carbon in a column

• The carbon granules strongly attract organic chemicals removing them from the water by a process called adsorption

• When the carbon is full and can't hold any more chemical, it is removed from the column, heated to burn off contaminants and can then be re-used.

Page 22: Water treatment plants

Water Treatment Plants 22

Distribution

• Pumping of the clean water produced at the treatment plant to the community is called distribution

• This can be done directly or by first pumping the water to reservoirs or water storage tanks

Page 23: Water treatment plants

Water Treatment Plants 23

Onsite Treatment Color, Taste and Odor

• The activated carbon technology used in municipal drinking water treatment can be applied in homes as well

• the carbon is contained in a "household-sized" column

• water passes through the carbon removing organic matter (which can cause a yellow color) and also compounds which cause unpleasant taste and odor

Page 24: Water treatment plants

Water Treatment Plants 24

Onsite TreatmentAt The Tap

• Home water treatment systems may also be installed at the tap

• Although the technologies vary somewhat among products, they typically include pre-filtration

• hardness and metals removal by ion exchange

• organic matter removal with activated carbon

• post-filtration

Page 25: Water treatment plants

Water Treatment Plants 25

US Bottled Water Sales

Page 26: Water treatment plants

Water Treatment Plants 26

Decrease in Tap Water Consumption

Page 27: Water treatment plants

Water Treatment Plants 27

Bottled Water vs Filtration System

Page 28: Water treatment plants

Water Treatment Plants 28

The Plastic Planet

Page 29: Water treatment plants

Water Treatment Plants 29

Implement A Project (5 Marks)Due Date: Wednesday, 10th April, 2013

Low Cost• Water Conservation• Water Treatment• Wastewater Treatment• Safe Drinking Water for

Flood Effected People• Rainwater HarvestingOr • Any Smart Idea related

to Public Health Engineering

Page 30: Water treatment plants

Water Treatment Plants 30

Page 31: Water treatment plants

Rawal Lake Water Treatment Plant

Page 32: Water treatment plants

Water Treatment Plants 32

Water Supply

• Water supply in Potohar region

• Groundwater- major source

• Groundwater is supplemented with

treated surface water

• Disinfectants

Page 33: Water treatment plants

Water Treatment Plants 33

Sources of Drinking Water in Rawalpindi

Two main sources of water in Rawalpindi. Groundwater

• Groundwater with Tube wells• located throughout the city• 290 tube wells in WASA controlled area • supplying approximately 28 MGD water to the

residents of Rawalpindi.

Surface water in the form of lakes• Surface water is supplied from Khanpur Dam (14.6

MGD) through Sangjani Water Treatment Plant• Rawal Lake through Rawal Lake Water Filtration Plant

(23 MGD).

Page 34: Water treatment plants

Water Treatment Plants 34

Ground- vs. Surface Water

Groundwater• constant

composition• high mineral

content• low turbidity• low color• low or no D.O.• high hardness• high Fe, Mn

Surface water• variable

composition• low mineral

content• high turbidity• colored• D.O. present• low hardness• taste and odor

Page 35: Water treatment plants

Water Treatment Plants 35

History

Initial Construction 1962-63

Capacity 14 MGDExecuting Agency WAPDAContractor WABAG, Germany

First Extension (7 MGD) 1975-79

Extended Capacity. 21 MGDExecuting Agency PHED, Govt. of PunjabContractor M/S Federal Const. Corp. Lahore.

Second Extension (7 MGD) 2000-2002

Extended Capacity. 28 MGDExecuting Agency PMU, WASA/RDAContractor VA TECH. WABAG GmbH,

Austria.

Page 36: Water treatment plants

Water Treatment Plants 36

Main Components

• Screening• Coagulation• Aeration• Flocculation• Sedimentation• Filtration• Disinfection or Chlorination• Lime Dosing

Page 37: Water treatment plants

Water Treatment Plants 37

Components Screening

• 3 Bar Screens. • large pieces • form of branches of trees• leaves• clothes• plastic bags• dead animal

Aeration• 2 Blowers. Air flow @ 6 m3/min.• remove taste and odor problems from incoming raw water• Dissolved Oxygen (DO) level of water is enhanced by this process

Coagulation• 2 geared drives• shaft mounted mixers for alum mixing• coagulant delivery pipes

• alum is added and rapidly mixed with water • remove suspended particles in the form of turbidity

Page 38: Water treatment plants

Water Treatment Plants 38

Components

• Flocculation• Clarifier # 1 to 3

• 3 Mechanical Flocculation mounted on a central rotating full bridge with sludge scraper rotating bridge

• Clarifier Area = 475 m2

• Up flow velocity = 2.55 m/hr.• Total flow = 336 L/s

• Clarifier # 4• 4 flat bottom clarifiers Hydraulic flocculators (Vertical baffles) 16

sludge concentrator Cones• Clarifier Area = 4 x 190 = 760 m2

• Up flow velocity = 2.2 m/hr.• Total flow = 475 L/ s

• Coagulant is mixed through vertical baffling arrangements

Page 39: Water treatment plants

Water Treatment Plants 39

Components Sedimentation

• large flocs are removed by gravity settling• clear water is collected from the surface• settled material (sludge) removed from sedimentation tank• rotating vipers and sludge valves

Filtration• removal of suspended non settleable solids from the drinking water• supernatant water after sedimentation• passed through a 1.4 meter column of silica sand• effective size of 0.95mm (± 10 %) • filtration rate of 5.4 m/hr. (average)-6.5 m/hr (Max)(110-130 glns/ft2. /hr.)

Filter Backwashing• Conventional backwashing system includes• Compressed air• Air and Water• Water• Approximate time 12 to 20 minutes

Page 40: Water treatment plants

Water Treatment Plants 40

Filter Backwash• Sand is backwashed when

• It becomes clogged• Turbidity of filtered water gets too high

• During backwash, water is pumped upwards through the sand bed

• Sand becomes “fluidized”, and particles are flushed from the sand

• Dirty backwash water is pumped into a settling pond and either• Recycled back into plant or• Disposed

• Backwashing can consume 1% to 5% of a plant’s production

Page 41: Water treatment plants

Water Treatment Plants 41

Raw water

Coagulation

Aeration

Flocculation

Sedimentation Tank

Page 42: Water treatment plants

Water Treatment Plants 42

Page 43: Water treatment plants

Water Treatment Plants 43

Components

Disinfection or Chlorination• Liquid chlorine is used for this purpose• dosage rate varies from 1.5 to 2.0 mg chlorine

per liter of water • depending upon the level of contamination, pH,

and temperature• ensuring the residual chlorine upto 0.3-0.5 mg/l.

Lime Dosing • last unit process applied at Rawal Lake water

filtration plant• lime is used to adjust the pH of water

Page 44: Water treatment plants

Water Treatment Plants 44

Disadvantages of Chlorination

Chlorine is a dangerous chemical because1. it irritates the respiratory system2. it irritates the eyes3. can form Trihalomethanes, THMs, which are possible

carcinogens

Other disinfectant chemicalsOzone gas (O3)

Ultraviolet light (UV)

Not as desirable becauseMore expensive than chlorineCan’t maintain a residual concentration

Page 45: Water treatment plants

Water Treatment Plants 45

Water Quality Monitoring Program

• Water quality analysis laboratory• regularly monitor and analyze the quality of

water supplied through plant• equipped with latest instruments and chemicals • to test all the basic physico-chemical and

biological parameters • recommended by the World Health Organization• Urban Water Supply & Sanitation Project Phase I

Page 46: Water treatment plants

Water Treatment Plants 46

Serial No. Water Quality ParameterPHYSICAL PARAMETERS

1 Appearance

2 Color

3 Odor

4 Taste

5 Temperature

6 TurbidityCHEMICAL PARAMETERS

7 pH

8 Alkalinity

9 Hardness as CaCO3

10 Electrical Conductivity

11 Sulphate

12 Calcium

13 Magnesium

14 Total Dissolved Solids

15 Chlorides

16 Residual Chlorine

17 Nitrate as NO3-

18 Nitrite as NO2-

BACTERIOLOGICAL PARAMETERS19 Total Coliform Count

20 Fecal Coliform CountTOXIC SUBSTANCES

21 Arsenic as As +3/+5

22 Cyanide as CN-

Page 47: Water treatment plants

Water Treatment Plants 47

Treated Water Quality

• Turbidity. 1-3 NTU • Color. Colorless• Odor

Unobjectionable• pH 7.5 to 9.5• Residual Chlorine. 0.3 to 0.5 mg/L (at WW 1 and Topi WW)

• Coliform Bacteria Nil/100 ml

Page 48: Water treatment plants

Water Treatment Plants 48

Rawal Lake Catchment Area

Diplomatic Enclave

Malpur Village

Lakhwal Village

Q.A. University

Bari Imam

Poultry Waste from Murree

Bani Gala Village

Noor Pur Shahan

Filtration Plant WASA

Kurrang River

Chatter Park

Page 49: Water treatment plants

Water Treatment Plants 49

Upstream

Page 50: Water treatment plants

Water Treatment Plants 50

Shahdra Kass

Page 51: Water treatment plants

Water Treatment Plants 51

Bari Imam

Page 52: Water treatment plants

Water Treatment Plants 52

Bari Imam

Page 53: Water treatment plants

Water Treatment Plants 53

Bari Imam

Page 54: Water treatment plants

Water Treatment Plants 54

Bari Imam

Page 55: Water treatment plants

Water Treatment Plants 55

Human Activities at Korang River

Page 56: Water treatment plants

Water Treatment Plants 56

Quaid-e-Azam University

Page 57: Water treatment plants

Water Treatment Plants 57

Pictorial View - Filtration Plant

RAWAL LAKE FILTRATION PLANT

Page 58: Water treatment plants

Water Treatment Plants 58

Intake Structure

WASA WASA

Page 59: Water treatment plants

Water Treatment Plants 59

Main Building

WASA

Page 60: Water treatment plants

Water Treatment Plants 60

Main Electrical Control Panel

WASA

Page 61: Water treatment plants

Water Treatment Plants 61

Circular and Rectangular Clarifiers

Rectangular Clarifier

CircularClarifier

Filtration Media

WASA

Page 62: Water treatment plants

Water Treatment Plants 62

Filtration System

WASA WASA

Page 63: Water treatment plants

Water Treatment Plants 63

Filtered Water Collection System

WASA

Page 64: Water treatment plants

Water Treatment Plants 64

Lime Dosing System

WASA

Page 65: Water treatment plants

Water Treatment Plants 65

Safe Drinking Water

How can you ensure that your drinking water is safe?

a) Boilingb) Storing it safelyc) Drinking water from safe sourcesd) All of above

Page 66: Water treatment plants

Thank You