42
DEPARTMENT OF CIVIL ENGINEERING Water Treatment Content Content s s
| Date post: | 08-Feb-2016 |
| Category: |
Documents |
| Upload: | binyam-kebede |
| View: | 24 times |
| Download: | 0 times |
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Water Treatment
ContentsContents
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
How is water Treated ?How is water Treated ?
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Course Contents
1. Water Quality 1.1 Physical water quality parameters 1.2 Chemical water quality parameters 1.3 Biological water quality parameters 1.4 Drinking water quality standards
2. Conventional methods of water treatment2.1 Coagulation/flocculation Coagulation/flocculation 2.2 Sedimentation Sedimentation 2.3 Filtration Filtration 2.4 DisinfectionDisinfection
2.5 water softening 2.5 water softening 2.6 Iron and Manganese Removal2.6 Iron and Manganese Removal
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Course Contents
References:
MWH’s Water Treatment Principles and Design
HANDBOOK OF PUBLIC WATER SYSTEMS
Droste, R.L., Theory and Practice of Water and Wastewater Treatment, J. Wiley & Sons
Syed R. Qasim, Syed R. Qasim, Water Works Engineering: Planning, Design And Water Works Engineering: Planning, Design And Operation ( available in Library)Operation ( available in Library)
Tom D. Reynolds, Unit Operations and Process in Environmental Tom D. Reynolds, Unit Operations and Process in Environmental Engineering Engineering
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Paper Work - Group Assignment (30%)
1. Micro - and ultrafiltrationMicro - and ultrafiltration
2. Ion Exchange s1
3. Air Stripping and Aeration s1
4. Activated Carbon Treatment s1
5. Fluoridation and Defluoridation s1, s1
6. Dissolved air floatation
7. Desalination s1
8. Nanofiltration and Reverse Osmosis S1Nanofiltration and Reverse Osmosis S1
9. Iron and Manganese Removal s1Iron and Manganese Removal s1
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chapter OneChapter One
Water Quality
“Water is life”
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Characteristics Of Water
o There are Three categories used to describe drinking water quality.
Physical characteristics : relate to the quality of water for domestic use and are associated with the appearance of water.Chemical characteristics : derived from organic and inorganic matter and usually have significant health effects.Microbiological characteristics : relate to public health and can influence the physical and chemical characteristics of water.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Physical parameters include: Turbidity Color Taste and odor Temperature Conductivity PH Alkalinity Hardness TDS
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Turbidity Is the measure of suspended matter in water. Mostly caused by colloidal matter. Tends to protect pathogens from the disinfection
treatment of drinking water. The unit of measure is a nephelometric turbidity
unit (NTU). Regulations: 0.1 NTU as a goal, less than 1
NTU as a standard; less than 5 NTU as an exception for potable water.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING Geffersa Raw Water Geffersa Raw Water
( 60 NTU)( 60 NTU)
1111
Legedadi Raw WaterLegedadi Raw Water
( 400 NTU)( 400 NTU)
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Taste and Odor Mostly derived from natural biological process. In surface water taste and odor is caused by algae. In Ground water one of the most common offensive
chemical is hydrogen sulfide which imparts rotten egg odor.
One of the most often reported complaint by drinking water consumers is “chlorine taste”.
To control taste and odor problems, watershed supervision, use of algaecides and water filtration treatment.
When preventive action and conventional treatment not effective activated carbon is used.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING Taste/Odor Chemical Source
Chlorine taste & odor Chlorine Too much chlorine
Chlorine odor Chloramines Chlorine below breakpoint
Fruity odor Aldehydes Ozonation
Rusty or metallic taste Iron Naturally occurring, corroded pipes
Rusty or metallic taste Manganese Naturally occurring
Sulfur taste and odor Hydrogen Sulfide Naturally occurring
Musty taste and odor Geosmin Blue-Green Algae
Musty taste and odor 2-Methylisoborneol (MIB) Blue-Green Algae
Fishy, grassy Various Algae
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
PH Raw water examined for potential use as drinking
water has expected PH between 4 and 9. The PH is altered in water treatment process by
addition of chemicals. Even mildly acidic water influence the corrosive
action of water in the distribution system. In the range of PH expected in drinking water, there
is no direct effect on health. The minimum and maximum allowable PH range is
between 6.5 – 8.5 (WHO).
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Alkalinity Alkalinity is defined as the capacity of water to
neutralize acid. Due to the presence of bicarbonate, carbonate
and hydroxide. A minimum of approximately 15 mg/l is necessary
for Coagulation; a maximum of 100 mg/l is acceptable for domestic use.
There is no correlation between alkalinity and health in evaluation of drinking water quality.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Hardness Is represent the total concentration of calcium and
magnesium ions, reported as calcium carbonate. Hard water require more soap to produce foam. The other negative aspect of hard water is it
produce scale in hot water pipes, boilers and heaters.
Also hard water cause hair breakage and hair loss. A positive aspect is less dangerous to corrosivity
and with certain limit better taste.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Physical Characteristics of Water
Hardness Many studies in US, Canada and Europe relating to
soft water and a higher incidence of cardiovascular diseases as compared to the population served by hard water.
The theorized protective agents include Ca, Mg and suspected harmful agents include metals Cadmium, Lead, copper & Zinc ( which are found in higher concentration in soft water due to corrosiveness.
Surface water is softer than ground water. Softening treatment required when hardness is
greater than 150 mg/l.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Chemical Parameters include: Arsenic Fluoride Iron Manganese Lead Sodium Nitrate
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Arsenic GW expected to contain higher arsenic concentration
than surface water because of its presence in geological materials.
The arsenic species present in groundwater and surface water are largely arsenate and arsenite.
Arsenic in drinking water has been linked to lung, skin and urinary bladder cancer.
Arsenic in drinking-water will cause 200,000 – 270,000 deaths per year from cancer in Bangladesh alone.
Standards : WHO guideline < 0.05 mg/l
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Fluoride Fluorine appears in almost every kind of rock, therefore it
is exposed to weathering and transport to the surface and groundwater.
Ethiopia is one of the 23 countries where the population suffers from the consumption of fluorine rich drinking
water. Concentrations in drinking water above 1.5 mg/L cause
dental fluorosis. Prolonged intake of waters with a fluorine content higher
than 4 mg/L cause skeletal fluorosis. Sharply reduce dental caries formation the fluoride level
is 0.8 mg/l. WHO Guideline < 1.5 mg/l.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Sodium Sodium is a natural constituent of raw water, but its
concentration is increased by pollution sources. Sodium is considered harmful in drinking water at high
concentrations to person suffering from cardiac, renal and circulatory disease.
In an epidemiological study of students from two communities in USA, one with low (8mg/l) and one with high (107 mg/l) levels of sodium, higher blood pressure in the high level sodium community.
The American Heart Association recommends a water intake concentration not higher than 20 mg/l.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Iron In surface water supplies, presence of iron is due to
corrosion of pipes. In Ground water supplies, high content of iron
encountered due to elevated iron level in the earth strata. Water with dissolved iron (Fe) may appear clear at Water with dissolved iron (Fe) may appear clear at
first, but may form red particles as it oxidizes.first, but may form red particles as it oxidizes. Fe can form reddish-brown stains on laundry and Fe can form reddish-brown stains on laundry and
plumbing fixtures.plumbing fixtures. Taste and odor problems may be caused by iron Taste and odor problems may be caused by iron
bacteria.bacteria. WHO guideline < 0.3 mg/l. WHO guideline < 0.3 mg/l.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
INGRegion Zone Woreda Town Source Iron (mg/l)
Oromia
Jimma Jimma Jimma city River 0.43
Jimma Gumay Toba BH 0.5
Jimma Agaro Agaro BH No 1 0.82
Jimma Gera Chira River 0.49
Addis Ababa
Egziabherab
BH 0.8
Micheal (Yeca) BH 1.050
Gurdshola BH 1
Kara loke BH 0.888
Ayat 1 BH 0.706
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Chemical Characteristics of Water
Nitrate Lakes and Reservoir usually have less than 2 mg/l of
nitrate. Higher value of nitrate is found in ground water ranging
up to 20 mg/l. Methemoglobinemia (infant cyanosis or “blue baby Methemoglobinemia (infant cyanosis or “blue baby
syndrome”) has occurred in infants who have been given syndrome”) has occurred in infants who have been given water or fed formula prepared with water having high water or fed formula prepared with water having high concentrations of nitrate.concentrations of nitrate.
WHO Guideline < 10 mg/l
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Microbiological Characteristics of Water
Microbiological Parameters include :
Bacteria Viruses Algae Protozoa Fungi Helminths
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Microbiological Characteristics of Water
In nature, water contains all kinds of organisms and they are present in large numbers.
Also in drinking water many different organisms are found.
Most of the microorganisms found in drinking water are harmless to human health.
However there are also microorganisms that harmful to health, so called pathogenic micro-organisms.
Pathogenic microorganisms, are not present in water by nature, but they enter the water through feces and urine from humans and animals.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Microbiological Characteristics of Water
Pathogenic microorganisms can cause different diseases, which may become epidemic rather quickly in water.
They can be divided into three main groups, each with their own individual characteristics:
Pathogenic microorganisms Illness
Protozoa Diarrhea & stomach complaints
Bacteria Typhoid fever and cholera
Viruses Hepatitis and polio
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Microbiological Characteristics of Water
It is important to determine if pathogenic organisms are present in natural and treated water. The isolation and identification of specific pathogen is unfortunately very time consuming or difficult.
Fortunately, less harmful, easily isolated bacteria called indicator organisms can be used indirectly to detect pathogens.
Coliform bacteria is used as an indicator organisms. They live in the intestine of the human beings in large numbers, non disease causing, easily detectable.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Microbiological Characteristics of Water
The presence of coliform bacteria indicates that the water has been polluted with human or worm been polluted with human or worm-blooded animals waste. It is a warning signal that more dangerous bacteria may be present.
In WHO Guideline it is stated when testing 100 ml sample no E.coli must be found.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Drinking water quality standards
MCL – maximum contaminant levelMCL – maximum contaminant level- highest level of a contaminant allowed in drinking water- highest level of a contaminant allowed in drinking water- enforceable standard- enforceable standard
SMCL – secondary maximum contaminant levelSMCL – secondary maximum contaminant level
- non-enforceable guideline for managing drinking water - non-enforceable guideline for managing drinking water for for to taste, odour, and colour.to taste, odour, and colour.
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
SMCL
DEP
AR
TM
EN
T O
F C
IVIL
EN
GIN
EER
ING
Thank you!
