Water Quality Chapter 6 Water Sources WQT 121 Lecture 1

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Objectives Review Principle Water Quality Characteristics Reading assignment: Handout: Chapter 6 Water Quality Review Principle Water Quality Characteristics Understand common secondary MCLS. Effect of pH, Taste, Odor, Corrosion on water quality 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 < 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. True 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 Rainwater Seawater Lake Water Groundwater

Groundwater in comparison to surface water is generally: Lower in turbidity and higher in mineral content Higher in turbidity and lower in mineral content More susceptible to seasonal changes More susceptible to algal blooms 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 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 Rainwater Seawater Lake Water Groundwater

180 TDS mg/l, 7 mg/L Na, 23 mg/L Cl2, 40 mg/L SO4, 8 180 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 Rainwater Seawater Lake Water 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 clarifier. 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 TURBIDITY UNIT, or NTU. 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 problems 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? Total dissolved solids Temporarily dissolved solids Total disaggregated solids Total dissolved salts

The total solids in water would be a combination of: Fixed solids and settleable solids Dissolved solids and volatile solids Dissolved solids and suspended solids Suspended solids and fixed solids Fixed solids and dissolved solids

Total Dissolved Solids are dried at this temperature 103oC 105oC 180oC 550oC

The secondary MCL for TDS in drinking water is? 10 mg/L 500 mg/L 1,000 mg/L 1 mg/L A ____ sample is a discrete sample that is collected manually.

Key Words Turbidity A measure of the light scattering property of water (cloudiness) The unit of measure is the NEPHELOMETRIC TURBIDITY UNIT, or NTU. 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? Nephelometric turbidity unit Nephelometric total solids utilization Nepelometric turbidity utilization Nominal Turbidity Unit Nominal Tubidity Utilization A ____ sample is a discrete sample that is collected manually.

Turbidity is caused by? Dissolved solids Suspended particles Dissolved gases Dissolved colored solids A ____ sample is a discrete sample that is collected manually.

Which of the following is a major part of a turbidimeter? light aspirator Reference electrode Objective nosepiece A ____ sample is a discrete sample that is collected manually.

Turbidimeters must be calibrated: Monthly Quarterly If factory calibrated, never Daily Weekly A ____ sample is a discrete sample that is collected manually.

Which of the following parameters is used to indicate the clarity of water? pH Chlorine residual Turbidity Bacteriological A ____ sample is a discrete sample that is collected manually.

Which of the following substances will reduce the effectiveness of chlorine disinfection? color radon Turbidity Carbon dioxide A ____ sample is a discrete sample that is collected manually.

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 : ≤0.3 ntu ≤0.5 ntu ≤1.0 ntu ≤5.0 ntu A ____ sample is a discrete sample that is collected manually.

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

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

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

Color 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 A ____ sample is a discrete sample that is collected manually.

__________ can interfere with a turbidity meter measurement. SS concentration pH Color Temperature A ____ sample is a discrete sample that is collected manually.

Sludge accumulations in settling basins over a period of time usually: Add hardness to the water Increase the algae growth Result in taste and odor problems Result in the growth of pathogenic organisms A ____ sample is a discrete sample that is collected manually.

As water temperatures decrease, the disinfecting action of chlorine: Decreases Increases Remains the same 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? Thermal stratification Thermal justification Limnoptic layering Limnoptic stratification

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

Hard vs Soft Water 1. Hard Water 2. Soft Water Hardness: Ca+2 & Mg+2 250 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. > 250 mg/L (mostly Ca+2 and Mg+2). 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 sodium.

Drinking water average is about 250 mg/L as calcium carbonate hardness 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/ After EDTA titration indicator After EDTA titration To endpoint

Hardness #2340 hardness in mg/l as CaCO3 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 mg=CaCO3 milliMole)(1000 ml/L) ml of sample volume titrated

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. Color Temperature Time Ionic strength

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

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

pH Definition: The potential of hydrogen. Negative log of the hydrogen ion activity/concentration. Formula pH= -log10(αH+) The pH scale: -?.................................. 7 ....................................14 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. True False

Acid-Base pH Balance Figure 2.7

Which of the following pH readings indicates an acidic source water? 3 7 9 12

A water with a pH value of 7.00 is considered to be: Basic Acidic Hot Neutral 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?: pH and alkalinity Sulfates Chlorides Calcium and magnesium Total hardness

The pH is a measure of the concentration of _____ ____ in a solution Hydrogen ions Hydrozide ions Acid equivalents Base equivalents

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

pH sensors consist of A glass electrode and reference electrode A pH electrode and temperature electrode A junction electrode and null electrode

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

pH sensors measure the activity of which ion? Sodium Hydrogen Chlorine Caustic

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

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

Temperature does not affect pH measurement. True False

Water Properties Freezing point 0oC boiling point 100oC. 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 + - 104.5°

Water Impurities Dissolved, Colloidal, and Suspended solids- (acid, base, sand, clay, organics) Inorganic acids: sulfuric, nitric, hydrochloric, carbonic Bases: caustic soda, soda ash, hydrated lime Salts: ferric chloride, aluminum sulfate, sodium chloride 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) Hardness: Ca+2 & Mg+2 250 mg/L poor suds / soap ring mineral buildup (scale) fixture staining (white chalky) Ion exchange softening Lime - soda softening Sulfate salty off taste temporary diarrhea reverse osmosis / ion exchange TDS 500 mg/L high mineral content (salts) does not quench thirst, leaves mineral deposit Chloride salty taste contributes to corrosion 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 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 Lime Sodium bicarbonate Carbon dioxide Sulfuric acid

Taste 4 tastes Sweet Salty Bitter Sour 4 taste sensations hot cool astringent acrid

ODOR 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 carbon.

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.

MCL IOC and SOC SOCs IOCs Certain inorganic chemicals can be toxic when found in drinking water. Health effects include nervous system damage and cancer. Some of the regulated IOCs: arsenic, antimony, asbestos, barium, beryllium, cadmium, chromium, copper, cyanide, fluoride 4 mg/L, 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.

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 system 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 Strongly Agree Agree Disagree Strongly Disagree