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Water Quality Chapter 6 Water Sources


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Title: Water Quality Chapter 6 Water Sources

Water QualityChapter 6 Water Sources
  • WQT 121
  • Lecture 1

How was the reading assignment?
  1. Awesome (5 star)
  2. Good (4 star)
  3. Ok (3 star)
  4. Bad (2 star)
  5. A waste of my time (1 star)

Reading assignment Handout Chapter 6 Water
  • Review Principle Water Quality Characteristics
  • Understand common secondary MCLS.
  • Effect of pH, Taste, Odor, Corrosion on water
  • Review of MCLS key contaminants in water
  • 4. Hard verse soft water

Mineralogical Analysis of Water
  • Concentration (Mg/L) Quantity of a constituent in
    a standard volume (1 liter) is measured by its
    weight (in milligrams). 1 ppm (old school)
    1mg/L (correct)
  • General Mineral Content Ca, Na, Mg, Fe, Mn, HCO3,
    CO3, SO4 and Cl2.
  • Rivers lt 500 mg/L to 2,000 mg/L
  • Groundwater 100-10,000 mg/L

In the water treatment field, mg/L and ppm are
considered to be equivalent units.
  1. True
  2. False

3.5 salinity or 35,000 TDS (mg/L), 10,5000 mg/L
Na, 19,700 mg/L Cl2, 2,650 mg/L SO4, 1,310 mg/L
Mg, Ca 410 mg/L, Br 65 mg/L, Bicarbonate 152
mg/L, pH 8.1
  1. Rainwater
  2. Seawater
  3. Lake Water
  4. Groundwater

Groundwater in comparison to surface water is
  1. Lower in turbidity and higher in mineral content
  2. Higher in turbidity and lower in mineral content
  3. More susceptible to seasonal changes
  4. More susceptible to algal blooms
  5. Warmer and is quite soft

7.1 TDS mg/l, 7 mg/L Na, 1 mg/L Cl2, 2 mg/L SO4,
0.74 mg/L Mg, Ca 5.5 mg/L, pH 6.9
  1. Rainwater
  2. Seawater
  3. Lake Water
  4. Groundwater

180 TDS mg/l, 7 mg/L Na, 23 mg/L Cl2, 40 mg/L
SO4, 8.6 mg/L Mg, Ca 53 mg/L, pH 6.0-8.5
  1. Rainwater
  2. Seawater
  3. Lake Water
  4. Groundwater

Key Words
  • Dissolved Solids very stable inorganic or organic
    substances that remain in suspension.
  • Colloidal Solids Tiny clay and organic materials
    that float in water and repel each other.
  • Suspended Solids Large particles of silt and
    sand that settle out in a sedimentation basin or
  • National Secondary Drinking Water Regulations
    (NSDWRs) are non-enforceable guidelines
    regulating contaminants that may cause cosmetic
    effects (such as skin or tooth discoloration) or
    aesthetic effects (such as taste, odor, or color)
    in drinking water

Turbidity and Corrosion
  • Turbidity A measure of the light scattering
    property of water
  • The unit of measure is the NEPHELOMETRIC
  • Corrosion The destruction of metal by
    electro-chemical processes.
  • Corrosion is simply natures way to return metals
    back to their natural state OXIDES

Corrosion Factors
  • Low pH, which is often associated with EXCESS
    CARBON DIOXIDE in water
  • High oxygen
  • High total dissolved solids (salts) in the form
    of chlorides or sulfates
  • Soft water, or low hardness water
  • High temperature often exaggerates corrosion
  • 6. Low alkalinity

Corrosion Controls
  • Aggressive soil and water
  • Protective coatings inside and outside of pipe
    (cement lining is very effective for ductile iron
    pipe plastic wrap can effectively protect ductile
    iron pipe from soil corrosion)
  • 2.Cathodic protection, using zinc or magnesium
    sacrificial anodes to coat
  • 3.Adjust water chemistry by increasing the pH,
    adding alkalinity, or adding hardness ions
  • 4. Galvanic corrosion
  • Electro-chemical process similar to a battery
    that occurs when dissimilar metals are joined.

What does TDS stand for?
  1. Total dissolved solids
  2. Temporarily dissolved solids
  3. Total disaggregated solids
  4. Total dissolved salts

The total solids in water would be a combination
  1. Fixed solids and settleable solids
  2. Dissolved solids and volatile solids
  3. Dissolved solids and suspended solids
  4. Suspended solids and fixed solids
  5. Fixed solids and dissolved solids

Total Dissolved Solids are dried at this
  1. 103oC
  2. 105oC
  3. 180oC
  4. 550oC

The secondary MCL for TDS in drinking water is?
  1. 10 mg/L
  2. 500 mg/L
  3. 1,000 mg/L
  4. 1 mg/L

Key Words
  • Turbidity A measure of the light scattering
    property of water (cloudiness)
  • The unit of measure is the NEPHELOMETRIC
  • Corrosion The destruction of metal by
    electro-chemical processes.
  • Corrosion is simply natures way to return metals
    back to their natural state OXIDES

NTU stands for?
  1. Nephelometric turbidity unit
  2. Nephelometric total solids utilization
  3. Nepelometric turbidity utilization
  4. Nominal Turbidity Unit
  5. Nominal Tubidity Utilization

Turbidity is caused by?
  1. Dissolved solids
  2. Suspended particles
  3. Dissolved gases
  4. Dissolved colored solids

Which of the following is a major part of a
  1. light
  2. aspirator
  3. Reference electrode
  4. Objective nosepiece

Turbidimeters must be calibrated
  1. Monthly
  2. Quarterly
  3. If factory calibrated, never
  4. Daily
  5. Weekly

Which of the following parameters is used to
indicate the clarity of water?
  1. pH
  2. Chlorine residual
  3. Turbidity
  4. Bacteriological

Which of the following substances will reduce the
effectiveness of chlorine disinfection?
  1. color
  2. radon
  3. Turbidity
  4. Carbon dioxide

According to the Interim Enhanced Surface Water
Treatment Rule, a public water system serving a
population of 10,000 or more must maintain the
combined effluent turbidity of direct or
conventional filtration 95 of all measurements
taken each month at
  1. 0.3 ntu
  2. 0.5 ntu
  3. 1.0 ntu
  4. 5.0 ntu

The conductivity of the source water indicates
the quantity of dissolved material present
  1. True
  2. False

In general for every 10 units of Electrical
Conductance reported represents 6 to 7 mg/L
increases of dissolved solids
  1. True
  2. False

Electrical Conductance is reported in mmhos/cm
at 25oC.
  1. True
  2. False

  • Apparent color from light that is reflecting off
    the particles (giving it a yellow or straw color)
  • True color tea color that remains after
    filtering (organic acids from vegetation)
  • Units are CU or color units

What is apparent color?
  • Color in a sample after it is filtered
  • Color in a sample before it is filtered
  • Color in a sample after it is disinfected
  • Color in a sample before it is disinfected

__________ can interfere with a turbidity meter
  1. SS concentration
  2. pH
  3. Color
  4. Temperature

Sludge accumulations in settling basins over a
period of time usually
  1. Add hardness to the water
  2. Increase the algae growth
  3. Result in taste and odor problems
  4. Result in the growth of pathogenic organisms

As water temperatures decrease, the disinfecting
action of chlorine
  1. Decreases
  2. Increases
  3. Remains the same
  4. Depends on the altitude

As temperatures increase chemical reactions speed
up Arrhenius equation reaction rate doubles
every 10 degree celsius
Lake Stratification
  • Epilimnion- top of the lake
  • Thermocline- middle layer that may change depth
    throughout the day
  • Hypolimnion- bottom layer
  • Temperature change- from season create a cyclic
    pattern that is repeated from year to year.

The formation of layers of different temperature
in a body of water is called what?
  1. Thermal stratification
  2. Thermal justification
  3. Limnoptic layering
  4. Limnoptic stratification

Reservoir turnover is?
  1. Related to the pH of water
  2. Caused by denser water at the surface sinking
    toward the bottom
  3. Caused by wind cracking ice on the surface
  4. Needed to control algae growth

Hard vs Soft Water
Hardness Ca2 Mg2 250 mg/L poor suds / soap ring mineral buildup (scale) fixture staining (white chalky) Ion exchange softening Lime - soda softening sequestering agents
1. Hard Water Hard water is any water containing
an appreciable quantity of dissolved minerals. gt
250 mg/L (mostly Ca2 and Mg2). Precipitates on
pipes, Soap hard to lather because it reacts with
Ca and Mg salts in hard water. Need to use ion
exchange or treat with lime
2. Soft Water Soft water is treated water in
which the only cation (positively charged ion) is

Hardness 2340
  • What are typical values in nature?
  • Classification mg/L
  • Soft 0 - 17.10
  • Slightly hard 17.1 - 60
  • Moderately hard 60 - 120
  • Hard 120 180
  • Very Hard 180 over

Drinking water average is about 250 mg/L as
calcium carbonate hardness
Hardness 2340
How is it done?
Before w/ indicator
After EDTA titration To endpoint
Hardness 2340
  • What are the units and conversions?
  • hardness in mg/l as CaCO3

Calculations and Formulas? Hardness as CaCO3
mg/L (ml of EDTA (sample) ml of EDTA
(blank))(0.01 M EDTA)(100 mgCaCO3
milliMole)(1000 ml/L)
ml of sample volume
Hard Waters in the USA
Alkalinity and hardness are both analyzed by
adding a known reagent to the sample. This
process results in a ______ change.
  1. Color
  2. Temperature
  3. Time
  4. Ionic strength

This is the titrant used for the Hardness
  1. EDTA - A Chelating Agent
  2. 0.03 N Sulfuric acid
  3. 0.125 N Hydrochloric acid
  4. Sodium hydroxide

Hardness is defined as the sum of the _____ and
____ ions, although any divalent metal ion can
contribute to hardness.
  1. Calcium and Magnesium
  2. Magnesium and Sodium
  3. Calcium and Sulfate
  4. Struvite

  • Definition The potential of hydrogen. Negative
    log of the hydrogen ion activity/concentration.
  • Formula pH -log10(aH)
  • The pH scale
  • -?.................................. 7
  • Acid Neutral Basic
  • The pH range for drinking water is 6.5 to 8.5

Some characteristics of water, such as pH and
dissolved oxygen, change so quickly that they
need to be measured immediately.
  1. True
  2. False

Acid-Base pH Balance
Figure 2.7
Which of the following pH readings indicates an
acidic source water?
  1. 3
  2. 7
  3. 9
  4. 12

A water with a pH value of 7.00 is considered to
  1. Basic
  2. Acidic
  3. Hot
  4. Neutral
  5. Cold

When operating a surface water treatment plant,
which of the following laboratory tests is of
most significance for establishing chemical
dosages for coagulating water?
  1. pH and alkalinity
  2. Sulfates
  3. Chlorides
  4. Calcium and magnesium
  5. Total hardness

The pH is a measure of the concentration of _____
____ in a solution
  1. Hydrogen ions
  2. Hydrozide ions
  3. Acid equivalents
  4. Base equivalents

Which one of the following statements is true in
regard to the concept of pH?
  1. pH indicates the amount of total alkalinity
  2. A raw water sample with a pH of 6.5 is slightly
  3. The range of pH is between 0 and 14
  4. A pH meter gives the percent hydrogen ion
    concentration as its direct readout value.
  5. Accurate pH measurements on raw water require
    that a 24-hour flow-proporational sample be

pH sensors consist of
  1. A glass electrode and reference electrode
  2. A pH electrode and temperature electrode
  3. A junction electrode and null electrode

The range of a pH analyzer is
  1. 2 to 14 pH units
  2. 4 to 14 pH units
  3. 0 to 14 pH units
  4. 1 to 14 pH units

pH sensors measure the activity of which ion?
  1. Sodium
  2. Hydrogen
  3. Chlorine
  4. Caustic

What is the maximum recommended holding time for
a sample that is to be analyzed for pH?
  1. None it must be analyzed immediately
  2. 48 hours
  3. 7 days
  4. 14 days

What is the minimum number of pH standards needed
for calibration of a pH meter?
  1. 1
  2. 2
  3. 3
  4. 4

Temperature does not affect pH measurement.
  1. True
  2. False

Water Properties
  • Dipolar Molecule
  • High surface tension hydrogen bonding
  • Expands upon freezing (10)-more dense as liquid
  • Freezing point 0oC boiling point 100oC.
  • Most abundant liquid on surface of earth
  • Exist in 3 phases on earth (Triple point)
  • Universal solvent
  • High heat capacity
  • High heat of fusion
  • High heat of evaporation
  • High heat of vaporization

Water Impurities
  • Dissolved, Colloidal, and Suspended solids-
    (acid, base, sand, clay, organics)
  • Inorganic acids sulfuric, nitric, hydrochloric,
  • Bases caustic soda, soda ash, hydrated lime
  • Salts ferric chloride, aluminum sulfate, sodium
  • Organics volatile organic compounds (VOCs),
    synthetic organic compound

SMCL Water Quality Problem Treatment Methods
Iron 0.3 mg/L red water complaints taste and odor staining of clothing and fixtures (red -brown) chlorine filtration aeration filtration manganese green sand permanganate sequestering agents
Manganese 0.05 mg/L staining of clothing and fixtures (black or dark purple) chlorine filtration aeration filtration manganese green sand permanganate sequestering agents
Hardness Ca2 Mg2 250 mg/L poor suds / soap ring mineral buildup (scale) fixture staining (white chalky) Ion exchange softening Lime - soda softening sequestering agents
Sulfate 250 mg/L ?salty off taste? temporary diarrhea reverse osmosis / ion exchange
TDS 500 mg/L high mineral content (salts) does not quench thirst, leaves mineral deposit reverse osmosis / ion exchange
Chloride 250 mg/L salty taste contributes to corrosion reverse osmosis / ion exchange
Hydrogen Sulfide 0.1 mg/L rotten egg odor oxidize with chlorine, chlorine dioxide or permanganate
Odor 3 T.O.N. makes water un-palatable permanganate activated carbon (PAC, GAC) flushing programs
Color 15 colorunits makes water un-palatable effective coagulation
pH Effect Water Quality
  • Disinfection with Chlorine
  • Water pH has a big impact on chlorine
    effectiveness. Chlorines effectiveness is
    reduced at pH values above pH 7.
  • Corrosion Lead and Copper.
  • Low pH tends to make water more corrosive. A
    basic treatment technique to control lead and
    copper corrosion is to increase the pH.
  • Coagulation of Turbidity
  • Alum, the most popular coagulant if very
    sensitive to pH. Alum works best at a pH range
    of 6.5 - 7.5.

pH Adjusters
Raise pH Lower pH
Soda ash X
Caustic soda X
Lime X
Sodium bicarbonate X
Carbon dioxide X
Sulfuric acid X
4 tastes Sweet Salty Bitter Sour
4 taste sensations hot cool astringent acrid
  • Treated or finished water is diluted with odor
    free water until there is no perceptible odor.
    The dilution factor needed to achieve no odor is
    the ODOR THRESHOLD NUMBER. Odor free water is
    produced by treating tap water with activated

Causes of Bad Taste and Odor
  • Plankton various species of algae, especially
    blue green algae
  • Decayed vegetation-Decaying leaves are especially
    important in the late summer, early fall.
  • Dissolved minerals/gasses sulfates, chlorides,
    iron, etc.
  • Industrial chemicals phenolic compounds are
    especially a problem in very small
    concentrations, VOC, SOC,

MCL Inorganics Review
?Nitrate and Nitrite MCL are nitrate 10 mg/L, nitrite 1 mg/L, nitrate nitrate 10 mg/L Blue baby syndrome or methemeglobinemia, results in loss of oxygen to the brain, with possible brain damage. Infants 0 - 6 months most at risk. Sources include fertilizer, animal manure, and septic tank leachate
?Lead and Copper Action Levels for lead and copper (When the Action Levels are exceeded, corrosion control is required), lead 0.015 mg/L, copper 1.3 mg/L The health effect of lead is damage to the nervous system and lowered intellectual development, especially in developing children. The health effect of copper is minor, but can cause severe reaction in some individuals who are allergic to copper. Lead and copper are regulated in a Treatment Technique which requires systems to take tap water samples at sites with lead pipes or copper pipes that have lead solder and/or are served by lead service lines. The action level, which triggers water systems into taking treatment steps if exceeded in more than 10 of tap water samples, for copper is 1.3 mg/L, and for lead is 0.015mg/L.
?Fluoride Fluoride MCL 4 mg/L Causes mottling of teeth and may cause bone deformation or fluorosis Fluoride is a naturally occurring mineral that is normally present in groundwater.
  • ?IOCs
  • Certain inorganic chemicals can be toxic when
    found in drinking water.
  • Health effects include nervous system damage and
  • Some of the regulated IOCs
  • arsenic, antimony, asbestos, barium, beryllium,
    cadmium, chromium, copper, cyanide, fluoride 4
  • lead regulated by action levels as part of the
    lead/copper rule
  • mercury
  • nitrate, nitrite 10, 1 mg/L (nitrate nitrite
    must not exceed 10)
  • selenium
  • Thallium
  • ?SOCs
  • MCL, Health Effects, Sources, Sampling
  • Synthetic Organic Chemicals make up most of the
    regulated contaminants in drinking water! These
    chemicals are typically carcinogens. Examples of
    SOCs include
  • Pesticides like 2-4,D, methoxychlor, chlordane,
    di-methly bromide, dioxin
  • Solvents like TCE, carbon tetrachloride, benzene
  • Industrial chemicals like styrene, PCBs

MCLs DPB, Radionuclides, VOC
?THMs and other Disinfection By-Products (DBPs) Tri Halo Methane, or THM is the original regulated disinfection by-product. Most familiar is chloroform. THM MCL 0.1 mg/L Considered a carcinogen THMs form as the result of chlorine reacting with organic material in water, especially humus-like substances. Sampling required for chlorinated systems greater than 10,000 pop., once each quarter. A running average is calculated. Halogenated Acetic Acid, or HAA6 is an important new disinfection by-product MCLs for disinfectants free chlorine 4 mg/L chloramine 4 mg/L chlorine dioxide 4 mg/L ozone 0
?Radionuclides Radionuclides emit alpha, beta and gamma radiation that can result in an increased risk of cancer from exposure. Contamination of water is the result of natural radioactive minerals in geologic strata.
?VOCs Volative Organic Compounds that are readily lost from water if it is exposed to air. They are a problem in groundwater not surface water. VOCs are chemicals used as solvents, cleaning agents, and gasoline additives VOCs are suspected carcinogens examples are the gasoline additives called BTEX benzene toluene ethylbenzene xylene MTBE is a new concern in drinking water!

MCL Microbiological Turbidity
?Coliform Bacteria and Turbidity Coliform bacteria are generally harmless indicator bacteria. They indicate possible fecal contamination and the potential for waterborne pathogens to be present. No more than 5.0 samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive). Every sample that has total coliforms must be analyzed for fecal coliforms. There cannot be any fecal coliforms. Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human animal wastes. Microbes in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. Turbidity does not have a health effect. Turbidity is regulated for the following reasons it may interfere with the disinfection process it may hide or protect microorganisms from the action of disinfectants At no time can turbidity (cloudiness of water) go above 5 nephelolometric turbidity units (NTU) systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95 of the daily samples in any month.

(No Transcript)
Breakpoint Chlorination
  • Zone I Chlorine is destroyed by reducing agents
    such as iron, manganese, clay and silt. Chlorine
    reduced to chloride
  • Zone II Chlorine comes into contact with
    organics and ammonia. Chloroorganics and
    chloramines are formed.
  • Zone III Chloroorganics and chloramines are
    partially destroyed. Chloramines are broken down
    and converted to nitrogen gas which leaves the
  • Zone IV Breakpoint. Beyond this point, free
    available residual is formed. Some
    chloroorganics still remain as combined residual.
  • Chlorine demand is difference between applied
    chlorine and the free chlorine residual at any
    two points on the breakpoint curve.

The objectives for this week to become familiar
with basic characteristics of drinking water
quality has been met
  1. Strongly Agree
  2. Agree
  3. Disagree
  4. Strongly Disagree
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