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Potable Water

Chapter 4 REHS

"potable" look good, free from turbidity, color, odor, taste and disease
"potable water management" the science and practice of protecting surface and ground water
"public water system" piped water with 15 service connections and serves 25 individuals at least 60 days of the year
microbiological quality of water expressed in these terms concentration, frequency or +/_ of bacteria
who is in charge of water standards The EPA under the SWDA
3 additional water tests (critter type) crypto, giardia, legionella
Interim Standards 1975, specify's MCL
Maximum contaminant level maximum allowable concentration of contaminant
surface water open to the atmosphere
zone of saturation all the openings or voids are filled with water
ground water water in the zone of saturation
percent of disease related to inadequate water and sanitation 80%
snow in 1845 london water pump cholera
gambierdiscus toxicus tropical marine dinoflagellate that synthesis ciguatoxin
2 waterborne protozoa giardia and cryptosporidium
asiatic cholera outbreaks london in 1849 and 1853 investigated by john snow
vibrio cholerae in 1892 koch isolated from polluted Elbe river
multiple barriers for safe water (6) 1) source water protection 2) treatment plant processes 3) disinfectin 4) distribution 5 ) security 6) education
one of the first biological warfare weapons smallpox given to N.A. Indians on blankets 3 points of entry for anthrax
plague gram-, non motile Yersinia pestis zoonotic
3 forms of plague bubonic, septicemic and pneumonic
Halogenated Hydrocarbons (examples) PCB's, DDT, PBB's, chloroform, vinyl chloride
4 groups of chemicals in drinking water 1. halogenated hyrocarbons and organics 2. heavy metals 3. nonmetallic inorganics 4. biological contaminants, drugs and additives
public water system 15 connections, 25 individuals daily at least 60 days of the year
community water system 15 connections for year-round or serves 25 year round residents]
noncommunity system public sysem that is not a community system and can be transient noncommunity or (TWS or NTNCWS) parks, rest stops, 25 people but not the same 25 people
main drinking water contaminant sewage
most widely used bacterial indicator coliform
examples of disinfectants for water fre and combined chlorien, chlorine dioxide, ozone, UV irradiation. Chlorine is the most common
disinfectant byproduct Trihalomethant (THM) is most common
THM examples chloroform, bromoform, dibromochloromethane
Ozone the most pwerful disinfectant but is unstable in water
minimum requirement of free chlorine o.2ppm as set by National Interim Primary Drinking Water Regulations
factors that influence the movement of groundwater geological formation and permeability, rainfall and infiltration and hydraulic gradient
geomagnetics magnetic field used to find buried metals
electromagnetics measures difference in conductivity (finds boundaries of contaminated plumes around landfills with leachate
electrical resistivity resistance with probes- identifies porosity and ground water limits
ground-probing radar uses radar to measure reflection from water table
photoionization meters finds specific volatile compounds like gasoline, methane
microbes travle a shourt distance though (soil) sandy loam or clay
acidic soil increases movement of pollutants in soil
petroleum products tend to ____ float
halogenated solvents tend to migrate___ downward
removing bacteria from liquid in soil is inversely proportional to particle size of the soil
soil for removing viruses fine loamy sand over course sand
igneous rocks formed by cooling and hardening of molton rock. Not good source of water granite, dioxite, basalt (some water)
sedimentary eroded rocks like sand, gravel, clay, silt, loess usually a lot of water especially sandstones, shales and limestones
metamorphic heat and pressure on igneous and sedimentary (small amount of water)
karst areas caves, channels, rapid groundwater movement easily polluted
glacial drift sediment that is moved by glacier ice
porosity amount of water that can be held by rock or soil
effective porosity or specific yeild percentage of total volume or mass of water that drains freely our by gravity
specific retention volume of water retained
permeability or hydraulic conductivity rate of flow of water at 60F in gallons per day through cross section of 1ft2
transmissivity hydraulic conductivity times saturated thickness of aquifer
Darcy's Law Q=KIA (Quantity of flow per time, gpd=(hyd. Conductivity)(hydraulic gradient)(cross sectinalarea)
Groundwater Class 1 special groundwater-irreplaceable and ecologically vital
Groundwater Class 2 current and potential sources of drinking water
Groundwater Class 3 not considered potential sources of drinking water salt water
standard plate count total colonies of bac developing from measured portions (two 1ml and two .1ml) 48 hrs at 95F
guinea-worm most comon dracontiasisnhelminth
odor less than 3 on threshold odor number
taste not objectionalble
turbidity 0.5 Nephelometric turbidity units and occasionaly not more than 1NTU
color less than 15 true color units
temperature less than 60F
dug well 15-30 ft deep, not dependable
bored well uses an auger to go 25-60 feet, small yields, easily pollulted
driven and jetted wells pounded in and 50-100 feet deep
drilled well in general, they are better, less contaminated
chlorine dioxide more bowerful biocide than free cholorine but doesn't persist as long
ozone most powerful disinfectant but highly unstable in water and lacks persistent redisual so usually add a secondary like chlorine
uv radiation good biocide but no persistend residual
coagulation-flocculation combine small particles into aggregates as part of a process (coagulation, sedimentation, flitration)
coagulant formation (add what?) add chemical like alum
The first 3 steps of Coagulation in Coagulation-Flocculation Coagulant formation (alum), particle destabliization, interparticle collision
flocculation small particles transformed into larger pieces or floes
seidmentation and flotation solid-liquid gravity separation
flotation introduce gas bubbles into water that attach to solids to float to top
filtration suspended matter is removed (clay, silt, organic matter,
mandated by the EPA surface water treatment rule filtration- enterovirus, giardia, legionella, reduces crytosporidium resistent to disinfection
most common type of filter granular media filter
slow sand filter very effective, grain size .25-.35mm
rapid filtration treated water through granular media bed larger sand (.5-.7mm) PRE-TREATMENT is essential
Pressure filters sometimes used in rapid filtration. Water enters filters under pressure
standard for lead 15ppb flush for several minutes a day to reduce problem
standard for copper 1500 ppb may be naturally occuring causes of copper in water
what and where are radionuclides raduim, uranium, polonium, can test radon in ari. Shallow wells more likely to have these
human caused contamination of water nitrates, pesticides, VOC's, hazardous materials spills
VOC's examples solvents, cleaners, degreasers, benzene, toluene, fuel suppliers, dry cleaners, paint shops
VOC's healh effects CNS impairment, liver and kidney, skin, cancer
definition of coliform bacteria rod shaped, gram negative, non-spore forming, lactose fermenting with production of acid and gas at 35C
E. coli ferments lactose at 44F. Metallic green colonies on dark purple plate
membrane filtration sample vacuumed through a special filter that is sealed off in growing medium 44F
ONPG-MUG colilert and colisure 35C for 24 hours
dissolved oxygen the amount of oxygen available in fresh water
BOD amount of oxygen in water for microorganisms to decompose organic material - a measure of pollution
BOD Test and cause 5 days- canneries, dairy plants
when bod is high, DO is when DO is low (less pollution), BOD is
COD (Chemical Oxygen Demand) oxygen equivelant of what is susceptible to oxidation by strong chemical oxidant
standard for arsenic 10ppb
dissolved oxygen the amount of oxygen available in fresh water
BOD amount of oxygen in water for microorganisms to decompose organic material - a measure of pollution
BOD Test and cause 5 days- canneries, dairy plants
when bod is high, DO is when DO is low (less pollution)
COD (Chemical Oxygen Demand) oxygen equivelant of what is susceptible to oxidation by strong chemical oxidant
soil conditions for removal of virus and bacteria fine loamy sand over course sand and gravel
this water organism dies off quickly outside of host streptococcus
very resistant to unfavorable conditions and indicate past or present pollution C. perfringens (intestines of humans and anumals) more resistant than escherichia and streptococci
most dependable water well drilled well
best method for back flow preventor air gap
what causes water hardness dissolved calcium, magnesium bicarbonates, sulfates and chlorides
problems with hard water pipes clog and heaters become coated with lime scale
what fixes hard water water softener like
common disinfection of water chlorine, chlorine-ammonia compounds and ozone
hydropneumatic tank or pressure systems are commonly used for small communities, housing developments, private homes, camps, hotels
hydropneumatic tanks typically contain what percent of its volume as water? 10-20%
nitrate levels MCLG for nitrate is 10 mg/L or 10 ppm
nitrate presence indicates previous pollution
can diatomaceous earth filters stand alone? no, they need to be augmented wit chlorine
epilimnion top mixed zone of reservoir- high in o2 and algae
metalimnion or thermocline transition zone of reservoir, ox decreases, best source of water
hypolimnion zone of stagnation, cold, deficient in oxygen
hydrogen sulfide in water rotten egg smell, makes water corrozive, death at 300 ppm
best way to remove nitrates ion exchange is most practical. Reverse osmosis and electrodialysis are effective but expensive.
removal of cadmium can be removed more than 90% through iron coagulation. Reverse osmosis in not practical.
prevent backsiphonage by (3) vacuum breaker, air gap, backpressure units
backpressure pressure from nonpotable exceeds pressure from potable
backsiphonage pressure in public water system is less than that in non-potable due to a vacuum or reduced presure in potable
Q=AIR watershed runoff and reservoir design
how should a drilled well be sealed? cement grouting
sodium chloride used in water softeners
plain sedimentation quiescient (still) water settling using gravity to collect solids
centrifugal pump design depends on impeller
sodium hypochlorite (NaCl) can be used full strength for disinfection of water
pressure filter and DE earty filter commonly used for filtration of industrial water supplies an swimming pools, generally not drinking water
"fresh polllution" indicator free ammonia
effectiveness of chlorine depends on pH, temp, contact time, clarity
copper sulfate used to control growth of algae and protozoa
gases found in water that encourage corrosion carbon dioxide and h2o
Nephelometric turbidity units mesures amount of light scattered
testing for residual chlorine DPD-colormetric
granulated activated carbon filters used for treating water for drinks, removing taste and odor and removing organic chemicals (suspected carcinogens)
ozone treatement levels 1.0-1.5 mg/l
ozone treatment goals remove color taste and odors, viruses, cysts and bacteria
control of inorganic chemicals in drinking water sanitary survey, source ID, determination of amount of pollutants
trihalomethanes are created during: prechlorination with long contact periods and sunlight langelier saturation index
hydraulic ram is powered by water- water flowing in pipe is used to elevate a smaller quantity of water
centrifugal pump max water lift 15 feet
jet pump lifts water up to 120 feet but efficient at 50 feet or less
GAC removes tastes and odors by adsorption
sewage travelled over ___ feet in sandy soil 200 feet
ideal water hardness level 50-80 mg/l
alkalinity levels (desirable) 30-100 mh/l
Created by: sanitarianpankey
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