Chlorine is how many times heavier than air?
2.5
A quart of liquid chlorine will evaporate into how many quarts of gaseous chlorine?
450
At what temperature does a fusible plug melt?
Between 158° and 165°F.
How many fusible plugs are there on a ton cylinder?
6
How many fusible plugs are there on a 100 or 150 pound chlorine cylinder?
1
What is the most common cause of a chlorine leak?
Lead washer failure or failure to change lead washer
What type of respirator is needed when entering a chlorine room?
SCBA
What is the IDLH for chlorine?
10
How many ppm of chlorine in a room will bring death in seconds?
1,000 ppm or 0.10% by volume
What percentage of the air is oxygen?
20.9%
What chemical is used to oxidize iron from water?
Chlorine
How do you open a chlorine cylinder?
With a six inch box wrench.
The iodometric test is used to test for what parameter?
Ozone Residual
What is the minimum free chlorine residual for the distribution system?
0.2 mg/L
What is the minimum combined residual?
0.6 mg/L
What is the maximum residual disinfectant level?
4 mg/L
What does the C in CT value mean?
Concentration of the chlorine residual
What is measured from the chlorine application point to the point
where the chlorine
residual is taken?
Time
What does the T mean in CT value?
Time
How many pounds of chlorine can you withdraw from a ton cylinder in a day?
400 pounds
How many pounds of chlorine can you draw from a 100 or 150 pound
cylinder in a
day?
40 pounds
When chlorine is used to disinfect drinking water, the chlorine cylinders are placed on what device to measure usage?
Scale
What is a device used to measure the flow rate of liquid or gasses?
Rotameter
The chlorine scale reading does not equal the rotameter setting for the pass 24 hours. What is the most likely cause?
Air leak down stream of the chlorinator
Pumping dry air into a container or cylinder to assist with the withdrawal of a liquid or gas is called?
Air padding
What is an open or vertical drop or space that separates a potable drinking water supply from an unapproved water or nonpotable water called?
Air gap
What is the most common cause of water borne illnesses in the US?
Cross-connection
What method is considered the most reliable in measuring chlorine residuals?
What method is considered the most reliable in measuring chlorine residuals?
The addition of chlorine until the demand is satisfied and, thereafter, every drop of chlorine added is free residual is called?
Breakpoint chlorination
What is the disadvantage of breakpoint chlorination?
THM formation
Substances which cause cancer are called?
Carcinogens
What do you call a substance that changes the speed or yield of a chemical reaction without being consumed or chemically changed?
A catalyst
What parameter is determined by this formula? Cl₂ dosage- Residual =?
Demand
What do you call the indicator organism that is found in the intestines of warm blooded animals, including human beings, and in plants, soil, water, and air?
Coliform
What is DPD used for?
Measuring chlorine residuals.
Why is chlorine added to drinking water?
To disinfect the water
How many pounds of chlorine can you withdraw from a cylinder in 24 hours?
Depends on ambient temperature (8 pounds per degree F)
Disease causing organisms are called?
Pathogens
What does HTH mean?
High Test Hypochlorite
What does OCI mean?
Hypochlorite
What does HOCI mean?
Hypochlorous Acid
What is NaOCl?
Sodium Hypochlorite (bleach)
An increase in the heterotrophic plate count indicates?
Nitrification
What do the initials MPN mean?
Most Probable Number
What bacteria break down ammonia nitrogen to nitrites?
Nitrosomonas
Which bacteria break down nitrites to nitrates?
Nitrobacter
Which are the ideal conditions for nitrification to take place?
A dark environment, temperature between 25-30°C, a pH of 7.5-8.5, and free ammonia available
What is used to detect a chlorine leak?
Ammonia
What is used to detect a sulfur dioxide leak?
Ammonia
What is used to detect an ammonia leak?
Hydrochloric acid
If your plant is pre-chlorinating and you find that you are exceeding the MCL for THMS, what should you do?
Stop pre-chlorinating
Naturally occurring volatile organic compounds react with chlorine and form what cancer causing compound?
THMs
A pure chemical substance that is used to make new products or is used in chemical rests to measure, detect, or analyze other substances is called?
A reagent
The concentration of chlorine present in water after the chlorine demand has been satisfied is called?
Residual
Dosage
The Dosage is 5 pm and the residual is 3 ppm. What is the demand?
2 ppm
What do you call the process of adding a chemical reagent in small increments until completion of a reaction, as signaled by the end point?
Titration
What do you call the cloudy appearance of water caused by the presence of suspended and colloidal matter?
Turbidity
Why are water plant operators concerned with turbidity?
Turbidity interferes with disinfection
What is the MCL for turbidity?
0.5 Nephelometric units
Name four bacteria found in contaminated water?
Typhoid, Cholera, Dysentery, and Salmonella
Name two parasites that are found in contaminated water?
Cryptosporidium and Giardia lamblia
What determines the number of coliform samples that a water system has to take?
Population served
What is the MCL for coliform?
If a sample tests positive for coliform what actions should be taken?
Retest at the site within 24 hour notification of the positive test and sample one site upstream and downstream from the positive site.
If a water system samples 40 or more sites for coliform, how many positive samples are allowed?
2 or 5%
If a water system samples 39 or fewer sites for coliform, how many positive samples are allowed?
1
What are the optimum conditions for disinfection?
What are the optimum conditions for disinfection?
Why is turbidity of the water important?
High turbidity interferes with disinfection and coagulation
The Surface Water Treatment Rule (SWTR) requires what minimum level of water treatment?
Disinfection and Filtration
Besides chlorination and ammoniation, what other processes reduce pathogens in the water?
Coagulation, Filtration, and Sedimentation
Ultraviolet rays are used to disinfect water. What limits the UV rays efficiency?
No residual; also, if a pathogen is caught between two particles, the rays have no effect on the pathogen.
What color is chlorine gas?
Greenish-yellow
Chlorine cylinders are filled to what capacity?
85% to allow for the expansion of the liquid into the gaseous state
How many parts per million of chlorine is needed to oxidize one ppm
of H2S to
elemental sulfur?
2.08 mg/L
How many parts per million of chlorine is needed to oxidize one ppm of H2S to sulfates?
8.32 mg/L
If sulfur dioxide comes into contact with a person's mucous membrane, what can happen?
The formation of sulfuric acid (H₂SO₄)
What does this chemical reaction indicate? H₂S + Cl₂+O²2-→ S↓ + H₂O+2 Cl
Oxidation of H₂S by chlorine to elemental sulfur
What does this chemical reaction indicate?
H₂S+4 Cl₂+4 H₂O→ H₂SO₄ +8 HCI
Oxidation of H₂S by chlorine to sulfates or sulfuric acid (H₂SO₄)
In the last 4 questions, what do you call the oxidation process that took place?
Question 1:
What does this chemical reaction indicate?
H₂S+4 Cl₂+4 H₂O→ H₂SO₄ +8 HCI
Question 2:
What does this chemical reaction indicate? H₂S + Cl₂+O²2-→ S↓ + H₂O+2 Cl
Question 3:
If sulfur dioxide comes into contact with a person's mucous membrane, what can happen?
Question 4:
How many parts per million of chlorine is needed to oxidize one ppm of H2S to sulfates?
Sub-residual chlorination
n the normal pH range of drinking water, what is the usual form of chlorine?
Monochloramines
When you add ammonia to chlorine you form?
Chloramines
When chlorine is added to water what is the usual first reaction?
Chlorine is used up (destroyed) by reducing compounds (viruses, bacteria, solids, parasites, etc)
After the reduction of the chlorine dosage, what reaction takes place?
Chlororganics and chloramines are formed - residual is present
What is the next reaction in the chlorination chain?
Residual is reduced-chlororganics and chloramines destroyed
After the reaction in question 85, what takes place?
Breakpoint chlorination
What causes the swimming pool taste and odor in water?
Low chlorine residual-plant did not use breakpoint chlorination
What is the best residual for disinfection?
Free available chlorine
At water pH levels of 4.0 or lower, what form will chlorine take?
Trichloramine
Above pH of 7.5 chlorine is found as?
Monochloramines
Dichloramines and monochloramines exist together at what pH range?
5.5-7.5
Dichloramines and trichloramines are associated with what water complaint?
Tastes and odors
If chlorine is used to treat an odor caused by phenols (benzene), what happens?
The odor and taste are intensified
Customers are complaining of a sweet, aromatic, medicinal taste in the water. What is the likely cause?
Phenols
What is the best method to remove tastes and odors caused by phenols?
GAC
To avoid THM formation, what options are available to the WTP?
Switch disinfectants, remove the precursors, or form THMs and remove them after they are formed
What is the most common alternate disinfectant used to avoid the formation of THMs?
Chloramines
What is the highest chlorine to ammonia ratio by weight?
5 ppm Cl₂ as free residual to 1 ppm of NH₃
When measuring combined chlorine residuals (chloramines) in the field, what is the process?
Analyze for total chlorine (no free chlorine should be present at CI₂-NH₃ ratios of 3:1 to 5:1)
What is the MCL for Nitrites?
1
What is the MCL for Nitrates?
10
What is the combined MCL for nitrites and Nitrates?
10
Before moving a chlorine cylinder, what should you do?
Replace the protective cap
The chlorine cylinders have iced up. What is the likely cause?
Too rapid a withdrawal
In what direction do you turn a chlorine valve to open the cylinder?
Counterclockwise
How many turns does it take to open the cylinder valve fully?
1 complete turn opens the tank fully
If the bottom valve of a cylinder is leaking, what should you do?
Rotate the tank so the leak is at the top
A minimum PSI at the injector should be?
50 PSI
On a direct mount chlorinator, water is showing in the metering tube. What is the likely cause?
Check valve failure
What action is needed in question 110?
Question 110:
On a direct mount chlorinator, water is showing in the metering
tube. What is
the likely cause?
Clean or replace valve
On a direct mount chlorinator, water is venting into the atmosphere. What is the likely cause?
Excess water PSI
What action is needed in question 112?
Question 112:
On a direct mount chlorinator, water is venting into the atmosphere. What is the likely cause?
Remove vacuum regulator
On a direct mount chlorinator, there is no indication on flow meter when a vacuum is present. What is the likely cause?
Vacuum leak
On a direct mount chlorinator, there is an indication on the flow meter, but air is present, not chlorine gas. What is likely cause?
Gasket leaks.
If the DPD test is taken on water that has a combined residual, what error can take place?
False positive reading-precipitate forms and gives sample appearance of having color
Chlorinator will feed OK at maximum outputs, but there is no control at lower feed rates. What's the problem?
Vacuum Regulating Valve
Chlorinator will not reach maximum point. What's problem?
Faulty injector
Variable vacuum control will not go below 30% feed. Signal OK. What is causing problem?
CPRV
Variable vacuum control reaches full feed, but will not go below 50% feed rate. CPRV OK. What's causing the problem?
Signal vacuum too high
Variable vacuum control won't go to full feed. Gas pressure OK. CPRV OK. What's causing the problem?
Plugged restrictor
Low injector vacuum reading. What is the problem?
Flow restricted
There is an increase in the coliform level. What is the cause?
Low chlorine residual
There is a sudden drop in the chlorine residual. What causes this?
Increase in chlorine demand or drop in chlorine feed rate
What is used to detect a chlorine leak?
bottle can be used to spray ammonia vapors near the connections. A
white cloud Ans. Soak a rag with chlorine and hold it near
connections. Also, polyethylene spray
indicates a leak
How do you reduce high chlorine residuals before the water leaves the plant?
GAC or Sodium Bisulfate
If there is a leak around the chlorine valve stem, what action is needed?
Tighten the nut or stem by turning it clockwise
What chemicals can be used to neutralize chlorine?
Caustic Soda; Soda Ash; Lime
What kit is used to repair a defective ton cylinder?
B Kit
What kit is used to repair a 100 or 150 pound cylinder?
A kit
What is the maximum temperature that chlorine cylinders should be stored
100°C
ORP probes are used to measure what?
Direct measure of the disinfecting power of chlorine
Where should the ORP probe be located?
6.5 minutes downstream from the injection point
In rooms where there is chlorine or carbon dioxide present, what type of respirators should not be used?
Gas mask
What should you give some one who has inhaled chlorine?
Milk or peppermint spirits
What causes UV systems to be ineffective?
Scaling or fouling of the quartz sleeves. Also, high flow velocities; turbidity, and decline in lamp output
If 30 pounds of chlorine are used during an average week at a WTP, how many 150 pound cylinders will be used per month?
0.86 cylinder
Solution: Divide 30 pound/week by 7 days/week 4.3 lbs/day multiply this x 30 days= 129 lbs/month divide this by 150 lbs cylinder = 0.86 Cylinder
A water system treats 12.8 MGD. It doses the water with 5 ppm of chlorine. How many pounds of chlorine will the WTP use in 30 days?
5 ppm x 12.8 MGD x 8.34-534 lbs/day times 30 days= 16,013 lbs.
If the free chlorine residual leaving the plant is less than 0.2
mg/L, what action is
needed?
WTP/System is allowed up to 4 hours to correct problem
WTP/System is allowed up to 4 hours to correct problem
Equivalent to a detectable disinfectant residual
Bacteria found in the intestines of warm blooded animals, including human beings, and also in plants, water, soil, and air are called?
Coliform
Name three disease causing bacteria found in water?
Salmonella, Cholera, and typhoid
Which tablet is always found in a coliform sampling twirl bag?
Sodium Thiosulfate
Why is a space left in the twirl bag?
To allow for mixing
If the sample site is contaminated and you have no other sample site available, what should you do?
Swab the spigot with an NaOCl solution
What is the minimum amount needed to test for coliform?
100 mL
How long can you hold a sample collected for coliform?
6 hours
What test is also taken when the coliform samples are collected?
Chlorine Residual
What causes blue babies?
Nitrites
What do heterotrophic organisms use for their growth?
Organic Matter
Which substance in water increases the chlorine demand?
Nitrites
An increase in the heterotrophic plate count (HPC) indicates what process is taking place?
Nitrification
A HPC of less than 500 is an indication that there is a __?
Chlorine Residual
When taking samples for analysis by the lab, which of the following protocols must be followed?
Must fill out Chain of Custody Report