Presentation on theme: "Water Quality Chapter 6 Water Sources"— Presentation transcript:
1 Water Quality Chapter 6 Water Sources WQT 121Lecture 1
2 How was the reading assignment? Awesome (5 star)Good (4 star)Ok (3 star)Bad (2 star)A waste of my time (1 star)
3 Objectives Review Principle Water Quality Characteristics Reading assignment:Handout: Chapter 6 Water QualityReview Principle Water Quality CharacteristicsUnderstand common secondary MCLS.Effect of pH, Taste, Odor, Corrosion on water qualityReview of MCLS & key contaminants in water4. Hard verse soft water
4 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/LGroundwater ,000 mg/L
5 In the water treatment field, mg/L and ppm are considered to be equivalent units. TrueFalse
7 Groundwater in comparison to surface water is generally: Lower in turbidity and higher in mineral contentHigher in turbidity and lower in mineral contentMore susceptible to seasonal changesMore susceptible to algal bloomsWarmer and is quite soft
10 Key WordsDissolved 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
11 Turbidity and Corrosion Turbidity: A measure of the light scattering property of waterThe 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
12 Corrosion FactorsLow pH, which is often associated with EXCESS CARBON DIOXIDE in waterHigh oxygenHigh total dissolved solids (salts) in the form of chlorides or sulfatesSoft water, or low hardness waterHigh temperature often exaggerates corrosion problems6. Low alkalinity
13 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 coat3.Adjust water chemistry by increasing the pH, adding alkalinity, or adding hardness ions4. Galvanic corrosionElectro-chemical process similar to a battery that occurs when dissimilar metals are joined.
14 What does TDS stand for? Total dissolved solids Temporarily dissolved solidsTotal disaggregated solidsTotal dissolved salts
15 The total solids in water would be a combination of: Fixed solids and settleable solidsDissolved solids and volatile solidsDissolved solids and suspended solidsSuspended solids and fixed solidsFixed solids and dissolved solids
16 Total Dissolved Solids are dried at this temperature 103oC105oC180oC550oC
17 The secondary MCL for TDS in drinking water is? 10 mg/L500 mg/L1,000 mg/L1 mg/LA ____ sample is a discrete sample that is collected manually.
18 Key WordsTurbidity 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
19 NTU stands for? Nephelometric turbidity unit Nephelometric total solids utilizationNepelometric turbidity utilizationNominal Turbidity UnitNominal Tubidity UtilizationA ____ sample is a discrete sample that is collected manually.
20 Turbidity is caused by? Dissolved solids Suspended particles Dissolved gasesDissolved colored solidsA ____ sample is a discrete sample that is collected manually.
21 Which of the following is a major part of a turbidimeter? lightaspiratorReference electrodeObjective nosepieceA ____ sample is a discrete sample that is collected manually.
22 Turbidimeters must be calibrated: MonthlyQuarterlyIf factory calibrated, neverDailyWeeklyA ____ sample is a discrete sample that is collected manually.
23 Which of the following parameters is used to indicate the clarity of water? pHChlorine residualTurbidityBacteriologicalA ____ sample is a discrete sample that is collected manually.
24 Which of the following substances will reduce the effectiveness of chlorine disinfection? colorradonTurbidityCarbon dioxideA ____ sample is a discrete sample that is collected manually.
25 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 ntuA ____ sample is a discrete sample that is collected manually.
26 The conductivity of the source water indicates the quantity of dissolved material present TrueFalse
27 In general for every 10 units of Electrical Conductance reported represents 6 to 7 mg/L increases of dissolved solidsTrueFalse
28 Electrical Conductance is reported in mmhos/cm at 25oC. TrueFalse
29 ColorApparent 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
30 What is apparent color? Color in a sample after it is filtered Color in a sample before it is filteredColor in a sample after it is disinfectedColor in a sample before it is disinfectedA ____ sample is a discrete sample that is collected manually.
31 __________ can interfere with a turbidity meter measurement. SS concentrationpHColorTemperatureA ____ sample is a discrete sample that is collected manually.
32 Sludge accumulations in settling basins over a period of time usually: Add hardness to the waterIncrease the algae growthResult in taste and odor problemsResult in the growth of pathogenic organismsA ____ sample is a discrete sample that is collected manually.
33 As water temperatures decrease, the disinfecting action of chlorine: DecreasesIncreasesRemains the sameDepends on the altitudeAs temperatures increase chemical reactions speed upArrhenius equation: reaction rate doubles every 10 degree celsius
34 Lake Stratification Epilimnion- top of the lake Thermocline- middle layer that may change depth throughout the dayHypolimnion- bottom layerTemperature change- from season create a cyclic pattern that is repeated from year to year.
35 The formation of layers of different temperature in a body of water is called what? Thermal stratificationThermal justificationLimnoptic layeringLimnoptic stratification
36 Reservoir turnover is? Related to the pH of water Caused by denser water at the surface sinking toward the bottomCaused by wind cracking ice on the surfaceNeeded to control algae growth
37 Hard vs Soft Water 1. Hard Water 2. Soft Water Hardness:Ca+2 & Mg+2250 mg/Lpoor suds / soap ringmineral buildup (scale)fixture staining (white chalky)Ion exchange softeningLime - soda softeningsequestering agents1. Hard WaterHard 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 lime2. Soft WaterSoft water is treated water in which the only cation (positively charged ion) is sodium.
38 Drinking water average is about 250 mg/L as calcium carbonate hardness What are typical values in nature?Classification mg/LSoftSlightly hardModerately hardHard – 180Very Hard & overDrinking water average is about 250 mg/L as calcium carbonate hardness
39 Hardness #2340 How is it done? Before w/ After EDTA titration indicatorAfter EDTA titrationTo endpoint
40 Hardness #2340 hardness in mg/l as CaCO3 What are the units and conversions?hardness in mg/l as CaCO3Calculations 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
42 Alkalinity and hardness are both analyzed by adding a known reagent to the sample. This process results in a ______ change.ColorTemperatureTimeIonic strength
43 This is the titrant used for the Hardness analysis. EDTA - A Chelating Agent0.03 N Sulfuric acid0.125 N Hydrochloric acidSodium hydroxide
44 Hardness is defined as the sum of the _____ and ____ ions, although any divalent metal ion can contribute to hardness.Calcium and MagnesiumMagnesium and SodiumCalcium and SulfateStruvite
45 pHDefinition: The potential of hydrogen. Negative log of the hydrogen ion activity/concentration.Formula pH= -log10(αH+)The pH scale:-?Acid Neutral BasicThe pH range for drinking water is 6.5 to 8.5
46 Some characteristics of water, such as pH and dissolved oxygen, change so quickly that they need to be measured immediately.TrueFalse
48 Which of the following pH readings indicates an acidic source water? 37912
49 A water with a pH value of 7.00 is considered to be: BasicAcidicHotNeutralCold
50 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 alkalinitySulfatesChloridesCalcium and magnesiumTotal hardness
51 The pH is a measure of the concentration of _____ ____ in a solution Hydrogen ionsHydrozide ionsAcid equivalentsBase equivalents
52 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 14A 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.
53 pH sensors consist of A glass electrode and reference electrode A pH electrode and temperature electrodeA junction electrode and null electrode
54 The range of a pH analyzer is 2 to 14 pH units4 to 14 pH units0 to 14 pH units1 to 14 pH units
55 pH sensors measure the activity of which ion? SodiumHydrogenChlorineCaustic
56 What is the maximum recommended holding time for a sample that is to be analyzed for pH? None; it must be analyzed immediately48 hours7 days14 days
57 What is the minimum number of pH standards needed for calibration of a pH meter? 1234
58 Temperature does not affect pH measurement. TrueFalse
59 Water Properties Freezing point 0oC boiling point 100oC. Dipolar MoleculeHigh surface tension= hydrogen bondingExpands upon freezing (10%)-more dense as liquidFreezing point 0oC boiling point 100oC.Most abundant liquid on surface of earthExist in 3 phases on earth (Triple point)Universal solventHigh heat capacityHigh heat of fusionHigh heat of evaporationHigh heat of vaporization+-104.5°
61 SMCLWater Quality ProblemTreatment MethodsIron0.3 mg/Lred water complaintstaste and odorstaining of clothing and fixtures (red -brown)chlorine + filtrationaeration + filtrationmanganese green sand + permanganatesequestering agentsManganese0.05 mg/Lstaining of clothing and fixtures (black or dark purple)Hardness:Ca+2 & Mg+2250 mg/Lpoor suds / soap ringmineral buildup (scale)fixture staining (white chalky)Ion exchange softeningLime - soda softeningSulfatesalty off tastetemporary diarrheareverse osmosis / ion exchangeTDS500 mg/Lhigh mineral content (salts) does not quench thirst, leaves mineral depositChloridesalty tastecontributes to corrosionHydrogenSulfide0.1 mg/Lrotten egg odoroxidize with chlorine, chlorine dioxide or permanganateOdor3 T.O.N.makes water un-palatablepermanganateactivated carbon (PAC, GAC)flushing programsColor15 colorunitseffective coagulation
62 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 TurbidityAlum, the most popular coagulant if very sensitive to pH. Alum works best at a pH range of
63 pH Adjusters Raise pH Lower pH Soda ash X Caustic soda Lime Sodium bicarbonateCarbon dioxideSulfuric acid
65 ODORTreated 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.
66 Causes of Bad Taste and Odor Plankton: various species of algae, especially blue green algaeDecayed 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,
67 MCL Inorganics Review Nitrate and Nitrite MCL are: nitrate = 10 mg/L, nitrite = 1 mg/L, nitrate + nitrate = 10 mg/LBlue baby syndrome or methemeglobinemia, results in loss of oxygen to the brain, with possible brain damage. Infants months most at risk.Sources include fertilizer, animal manure, and septic tank leachateLead and CopperAction Levels for lead and copper (When the Action Levels are exceeded, corrosion control is required), lead = mg/L, copper = 1.3 mg/LThe 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.FluorideFluoride MCL = 4 mg/LCauses mottling of teeth and may cause bone deformation or fluorosisFluoride is a naturally occurring mineral that is normally present in groundwater.
68 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 rulemercurynitrate, nitrite 10, 1 mg/L (nitrate + nitrite must not exceed 10)seleniumThalliumSOCsMCL, Health Effects, Sources, SamplingSynthetic Organic Chemicals make up most of the regulated contaminants in drinking water! These chemicals are typically carcinogens. Examples of SOCs includePesticides like 2-4,D, methoxychlor, chlordane, di-methly bromide, dioxinSolvents like TCE, carbon tetrachloride, benzeneIndustrial chemicals like styrene, PCBs
69 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 carcinogenTHMs 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-productMCLs for disinfectants:free chlorine 4 mg/Lchloramine 4 mg/Lchlorine dioxide mg/LozoneRadionuclidesRadionuclides 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.VOCsVolative 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 additivesVOCs are suspected carcinogens; examples are the gasoline additives called BTEXbenzenetolueneethylbenzenexyleneMTBE is a new concern in drinking water!
70 MCL Microbiological & Turbidity Coliform Bacteria and TurbidityColiform 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 becontaminated 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 processit may hide or protect microorganisms from the action of disinfectantsAt no time can turbidity (cloudiness of water) go above 5 nephelolometricturbidity units (NTU); systems that filter must ensure that the turbidity go no higher than 1NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samplesin any month.
72 Breakpoint Chlorination Zone I: Chlorine is destroyed by reducing agents such as iron, manganese, clay and silt. Chlorine reduced to chlorideZone 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 systemZone 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.
73 The objectives for this week to become familiar with basic characteristics of drinking water quality has been metStrongly AgreeAgreeDisagreeStrongly Disagree