2018 C Water Study Guide Flashcards
What 4 parameters are used in the Langelier Index?
PH.Temp.Total Alkalinity.Calcium.
A negative Langelier Index indicates what?
Water is corrosive.
The Langelier Index is used to?
Find out if water is corrosive
What do colder temps do to water in Sedimentation?
Causes flock to settle at a slower rate.
When taking a sample for coliform, what is okay?
Set cap on clean surface.
Most expensive aeration device?
Mechanical
First symptom when inhaling fluoride?
Biting pain in the nose; nose bleed.
The MCL for Trihalomethanes?
0.08mg/l
In ion exchange softening which ions are exchanged?
Ca and Mg are exchanged for Na (Sodium).
The 4 stages of the operation of an ion exchange softener are?
Service, Backwash, Brine, Rinse.
Drinking water should be free of what?
Bacteria and Toxins.
One ton Cl2 tanks have how many fusible plugs?
6 to 8
The advantage of vacuum system chlorinators are?
Safer Operation.
What is the advantage of using monochloramines (Chloramines) for disinfection?
Less chance of THM formation.
What is a cross connection?
A connection between a drinking water supply and an unapproved water supply.
Lime and alum sludge are never mixed why?
Could cause an explosion.
What effect does Cl2 gas have on water?
Lowers the PH
A Venturi meter, propeller meter, etc., are used to measure what?
Flows
A common problem due to algae is?
Taste and Odors
What does lime do to PH?
Increases
The formula for Alum is?
Al2(SO4)3
What chemical is used to remove non-carbonate hardness?
Soda-Ash
What is the MCL for coliforms based on?
Presence and Absence
After being notified of a failed sample, how long for resample?
24 Hours
What is the secondary MCL for TDS?
500 mg/l
Why should Alum sludge never be applied to agricultural land?
It causes soil to harden.
What is between the impeller and volute?
Wear ring.
What is the cause for musty, fishy, and grassy odors in raw water?
Algal blooms.
Always do what with acid?
Add acid to water and wear eye protection.
An electrical fire is what class?
C Class
A unit that combines coagulation, flocculation, and sedimentation?
Solids contact unit.
Minimum contact/detention time in the flocculation basin when on conventional filtration?
30 Minutes
What is an Artesian Aquifer?
Water under pressure and rises to the surface.
What is the most common problem encountered with RO operation or membrane filtration?
Fouling of the membrane.
What is the most probable cause for violating the MCL for coliform count?
Low Cl2 Residual.
Media shrinking, cracking, and mud balls are all likely caused by?
Improper backwashing techniques.
The effluent from an RO unit is called?
Permeate
The increase in nutrients in a lake or reservoir is termed?
Eutrophication
What is the purpose of flash mixing and how long?
To rapidly mix chemicals; several seconds
What happens when you close the brine flow to an RO unit?
Fouling/damage to the membrane
At what PH will bicarbonate alkalinity start changing to carbonate alkalinity?
8.3
Reservoirs that are low in nutrients as well as aquatic animal and plant life?
Oligotrophic
If your total alkalinity is 160, and the phenolphthalein alkalinity is 81, what is the hydroxide alkalinity? (2P-TA=OH)
The answer is 2
Why is carbon dioxide dangerous to work around?
The possibility of suffocating
THM’s are produced faster at a higher?
Temp. and PH
Initial PH=8.7, Final PH=9.1; Initial Hardness=34 mg/L, Final Hardness=38 mg/L. What is this a result of and what does it mean?
A Marble test, and it means the water is undersaturated and corrosive.
What two types of lime are used in the lime softening process?
Hydrated lime and Quicklime
What is the removal of odor-producing substances that are volatile called?
Degasification
What would you clean a RO membrane with?
Acid/Citric Acid
How is PAC (powdered activated carbon) removed from a plant during treatment?
Filtration
Chemical solution pumps are?
Positive displacement pumps
A pre-coat of what is required to dewater gelatinous (jelly like) alum sludge?
Diatomaceous Earth
When raw water quality changes what adjustments may need to be made?
Coagulant Dosage
The jar test should be run at least daily and more often when?
The quality of raw water changes
What is earth composed mainly of the skeletal remains of diatoms?
Diatomaceous Earth
How many pounds of Cl2 can be removed from a 150lb cylinder within 24 hrs?
40lbs
What removes Cl2 residual out of a sample bottle?
Sodium Thiosulfate
When the MCL is violated with an “Acute Heath Risk” for fecal coliform notify within?
24 Hours
If you cannot tell a filter needs backwashing by headloss, how else can you tell?
Turbidity
The speed in a flocculator should be what in lower temps?
Increased
Metallic corrosion in potable water is always the result of an electrochemical reaction or?
The Galvanic cell
What is the first thing you do when you get to a plant?
Review what happened on the previous shift (log books)
How do you identify a coliform colony on the membrane filter method?
Metallic surface sheen
Upon residual analysis of a system using hypochlorination the Cl2 residual has continuously decreased over a given time period, what is the cause?
Hole in the supply line
What is the primary purpose of water treatment?
Provide safe and contaminant free water (free of toxins and harmful bacteria)
What has a medicinal smell?
Chlorophenol (Phenols)
How many mg/L of Cl2 does it take to oxidize hydrogen sulfide to sulfur & water?
2.08mg/L of Cl2 to 1mg/L of Hydrogen Sulfide
What do you sample for at the effluent end of treatment, before the distribution system?
Turbidity
What can cause the freezing of a chlorine tank (valves?)?
Cl2 reliquefied in the lines
When would you include Secondary MCL violations in your consumer report?
Whenever the secondary MCL is violated
What are 2 chemical characteristics of water?
Organic & Inorganic
When using aeration to oxidize iron & lab results show a high PH you can determine that the rate of precipitation will?
Increase ( the higher the PH the more iron can be removed)
If you have a small pore size in a pressure cartridge vessel what will be needed?
Increased Pressure
Limit for: Iron =
Manganese =
0.3mg/l
0.05mg/l
Carbonate hardness removed by?
Lime Only
Fatal doses of fluoride?
4-5g, about a tablespoon
Recarbonation
Lowers PH
Non-Carbonate hardness removed by?
Both Lime and Soda
Colloidal particulates removed by?
Chemical treatment and filtration
A vacuum filter press process control step is to do what?
The belt is washed before it reenters vat
Removing minerals from water: Phase change=
Nonphase change=
Freezing or distillation.
Reverse osmosis, electrodialysis, and ion exchange
Tubular membrane used to?
Treat wastewater with high suspended solids concentration
Air stripping feature to better enhance process?
Counter flow to air
Who hires plant safety policies and security?
Management
What reduces the formation of THM’s in water?
Lower PH
Do not do this when sampling for coliform?
Place Cap on Counter
If you need to lower hydroxide from a +12 to a +5 or+8, how would you lower it?
Carbon Dioxide
What season produces the most THM’s?
Summer
What chemical would you use as a pre-treatment in an R.O. unit to slow hydrolysis?
ACID
Lime and what removes noncarbonate hardness?
Soda Ash
What do you do if the temp decreases in a flash mixer?
Increase mixer
What is tapered energy mixing?
Reducing the surface area or paddle size
What is the minimum detention time in the coagulation/flocculation basin?
30 Min
The pressure in the distribution system should never drop below what p.s.i?
20 PSI
How long after a total coliform positive test do you have to re-sample?
24 Hours
What is the minimum residual allowed in the distribution system?
0.2
What is the number of bacteriological samples based on?
System Population
How is P.A.C (powder activated carbon) removed from the system before distribution?
Filtration
What type of valve is at the end of a well?
Foot Valve
What is used to measure water depth?
Bubbler Tube
