What is the IDLH for Sulfur Dioxide?
100 ppm (NIOSH/OSHA)
What is the process before water enters an Ion Exchange unit?
Pretreatment- Oxidation of Excess Iron (if chlorine is used as the 'oxidant then Dechlorination is needed).
To protect or keep a sample for a couple of days. Refrigerate (4° C/39°F)
Fix sample(add preservative)
When should sedimentation tanks be cleaned?
When sludge interferes with treatment. Or during off peak demand periods.
What happens when water velocity increases in a pipe?
Increases the corrosion rate and/or removes/reduces scaling on interior of pipes.
What is a treatment process that lowers pH?
1. Alum; 2. acid (RO Process & Enhanced Coagulation); 3.CO₂ Book
answer for lowering pH during lime
softening.
What is MCL for Odor?
3 TON (Threshold Odor Number)
Why is turbidity important?
1. Interferes with disinfection, 2. Increase Chlorine Demand, 3. Increases chemical demand.
Why are sulfates a concern?
1. Cause Scaling 2. Laxative effect.
What is a chemical that is commonly used to control corrosion?
Polyphosphate; Sodium Hexametaphosphate; Zinc Phosphate.
What is SMCL for Iron?
0.3 mg/L
When is the best time to get rid of BRINE?
During high flows periods at the sewer plant.
What causes bluish color in the water at WTP?
Overdose of alum.
What causes a pink color in water?
Overdose of potassium permanganate KMnO₄.
What causes a brownish-yellow color in a greensand WTP effluent?
Too much alkalinity, which means that the brown is probably iron that has not been oxidized out by chlorine because the alkalinity was too high. Best pH for iron oxidation by chlorine is 6.2-6.5.
A chemical formula is a shorthand way to write the name of a compound. Know this!
N/A
Greatest number of errors produced in a laboratory is usually caused by?
1. Improper sampling; 2. Poor preservation; 3. Insufficient mixing.
Iodometric test?
Ozone residual test.
New glassware is rinsed with acid before testing for?
A gate valve works like a?
Guillotine.
The amount of water in a lake or river is directly related to?
Rainfall.
What is an estuary?
The lower body of a river that is effected by tides.
A check valves allows water to flow?
Only in one direction.
The use of aeration in control of taste and odors is effective only in removing gasses and organics that are?
Volatile.
Discharge rate of a piston pump is?
Constant at a constant speed.
Lead & Copper rule promulgated on
June 7, 1991.
What is pH?
Measure of Hydrogen Ion activity.
What is proper way to test for Cl2 Leak?
Hold a rag soaked in ammonia under fittings. Ans. Use spray bottle, spray ammonia vapors.
How do you test for low turbidity?
Nephelometric method.
What is the most dangerous powder at the WTP?
Powdered Activated Carbon.
What does a WTP operator check for when he titrates from a pH 8.3 to pH 4.5?
TA.
TA.How many pounds of chemical are used in a reservoir with 0.5 mg/L dosage and 18 mg volume?
0.5 x 18 x 8.34
Convert 385 mg/L to gpg.
385 divided by 17.1
H2SO4 reacts violently when mixed with water. How do you handle acid 7 water?
Add acid to water.
Noncarbonate Hardness is determined when the TH is greater than the TA, you subtract the TA from the TH.
N/A
When the TH is greater than the TA the TA is- to?
Carbonate Hardness.
Customer complaints about a medicinal or sweet aromatic taste in the water. The water is treated with chlorine and the problem increases. What is the most likely cause?
Phenols.
In question 37, Customer complaints about a medicinal or sweet aromatic taste in the water. The water is treated with chlorine and the problem increases. What is the most likely cause? what is the best treatment?
GAC.
What method is best to deal with odors caused by volatile organics?
Aeration/air stripping.
Fishy, woody, septic, tastes and odors are caused by?
Algae.
What is most often used to treat or prevent algae and slime in the distribution
system?
Maintain free Cl₂. =.z
THMs are caused by a free chlorine residual with detention time in the presence of naturally occurring volatile organic precursors.
N/A
Fe and Mn are oxidized by?
Chlorine, aeration, potassium permanganate.
In lime softening, why is it important to control the pH?
Control scaling and corrosion.
When the gauge to read head lost is out of service, what parameter should then be used to backwash a filter?
Time and/or turbidity.
The most basic instrument or device to measure at a WTP is?
Mechanical.
At a WTP which are the two most critical things that an operator must consider for the day-to day operation and production?
Quality and quantity.
What determines the amount of knowledge that a plant operator needs to know on the job?
Size of plant (production) and treatment process.
What is the function of a check or foot valve?
Allows flow in only one direction.
PA 80 TA=148 What is OH?
2PA-T=OH or 160-148=12
In Q50, PA 80 TA=148 What is OH? what action is needed?
Decrease Lime Dosage.
What is the surface area of a clarifier that has a 50' radius?
3.14 x r²
What is surface area of clarifier 100' wide?
Same as question 52.
Question 52: What is the surface area of a clarifier that has a 50' radius?
Answer: 3.14 x r²
Water that is stable is saturated with
CaCO₃.
Math: How much water is removed from a tank that is 20' Wide and 10' deep and the operator runs the pump for 15 minutes to lower the level 5'?
3.14 x 10x 10 x 5' (water pumped) x 7.48.
3.14 x 10x 10 x 5' (water pumped) x 7.48.
Coagulation, flocculation, and sedimentation.
Solid contact units are critically limited in their stability when?
During rapid changes in flow and temperature.
The term disc refers to an eccentric valve's?
Plug.
What causes floc flowing over the launder weirs?
Insufficient alkalinity, too short a detention time for the flow, and under dosage of coagulant.
To close chlorine valve
turn counter clockwise.
During a jar test 80% of the floc settles in a minute. What is the problem?
Over dosage.
MCLs for Lead 0.015 mg/L (Mental retardation) Copper action Level 1.3, mg/L (Liver/Wilson's disease) TTHM 0.08 mg/L (Cancer), Iron 0.3 mg/L (Red water, brown stains in filter, red stains on fixtures, Mn 0.05 mg/L Black stains (Mn Precipitates cause black water), Nitrites 1 mg/L (Cause blue babies).
N/A
0.855 MG/month are used in backwashing filters at a WTP that produces 45 MG/Month. What percent is used to backwash?
.855 MG divided by 45 MG.
What cause hardness?
Magnesium and calcium; also alkalinity.
DO is normal through out distribution system, but it takes a precipitous drop at a sampling tap or faucet. What is the likely cause?
Corrosion.
Turbidity target
0.1 or less.
Coagulant used in Treatment plants?
Polymers, Alum, Ferric sulfate or chloride. Also, CaO and (Ca(OH)₂) used as coagulant aids.
Chemical used to control corrosion?
Polyphosphate.
Polyphosphate.
Air in line.
What is used to retard Mn or Fe from precipitating out of the water?
Polyphosphates.
Valves that open 90° or ¹/₄ of a turn?
Plug, Butterfly, Eccentric, globe.
Advantage of Centrifuges used to dewater sludge?
Can vary sludge thickness.
Aeration is more efficient in the removal of odors from water caused by
volatile organics.
When pH remains steady at 10, what precipitates are formed?
Calcium as CaCO₃.
What is the purpose of concrete curbing or walls and screens around drinking water sites?
Prevent debris and runoff from entering wells.
Where is the sanitary seal located on a well?
At the top.
What type of pump is used to deliver fluoride or any chemical?
Diaphragm or positive displacement pumps.
Before entering a chlorine room?
Make sure ventilation system is on.
When a positive displacement pump is pumped against a closed discharge valve, what happens?
Rupture (break) of pipe and damage to the pump.
400 lbs of Cl₂ is used to treat 10MGD. What is dosage ppm?
400 lbs divided by 8.34 x 10 MGD.
Where is the normal application point for zinc phosphate or any other polyphosphate at the WTP?
Filter influent/prior to filtration.
Air stripping is best for removing
high volatile organics.
When alum is added to the water it decreases the pH. Therefore, you must increase lime dosage. When alum dosage is decreased, lime dosage may be decreased. -
N/A
What is the purpose of a storage tank?
To provide water to meet peak hourly demands, and provide contact time for disinfection.
In Membrane Softening or RO what causes an increase in salt rejection?
Membrane compaction.
What is the best way to re-aerate a pond or reservoir?
Diffused air.
Which is the most expensive system for aerating a reservoir?
Mechanical.
Lime softening increases
THM formation because it raises pH.
Do not use a canister type gas mask for carbon dioxide or chlorine leaks. Carbon dioxides displaces oxygen and you may suffocate.
N/A
Flux decline is loss of water flow through the membrane due to
compaction and fouling of the membrane.
Air stripping is a process which combines elements of air blowers and waterfall or cascade devices, and baffles to achieve aeration.
N/A
What type of map describes the underground?
Geological.
What is a major factor in coagulation?
Alkalinity.
What ion is most for hypochlorite?
Sodium or calcium.
The amount of water in a lake or river is directly related to
rainfall.
Taste and odors treatment methods can be separated into two broad categories:
removal and destruction.
Presence and absence test is used to measure
Total coliform bacteria.
The absence of sodium thiosulfate in the coliform sample bottle would leave chlorine in the sample which would give false results.
N/A
The measurement of the hydrogen ion activity gives you what parameter?
pH.
The discharge rate of a piston pump is constant at a constant speed.
N/A
What test is used to measure the stability of water?
Marble test.
Bicarbonate alkalinity occurs at what pH level? Bicarbonate exists alone below pH 8.3...
N/A
Which of the following is used to measure the filtration rate?
Gpm/sq ft.
Automatic starting of the generator is not needed when?
Operator on duty for 24 hours seven days a week (24/7).
How is insoluble iron removed?
How is insoluble iron removed?
The most common causes of accident at a WTP are?
Negligence and carelessness.
What is used to measure the depth of a clearwell?
Air bubbler.
At which pH level is there more OCL (hypochlorite) than HOCL (Hypochlorous
acid)?
Above 7.
What height of water produces 1 PSI?
2.31'
An expression of the intensity of the basic or acidic condition of a liquid is called
pH.
Adding lime to water increases the hydroxide concentrations of the water and leads to
an increase in pH.
Carbonate hardness is caused by carbonate and bicarbonate ions (very sensitive to pH) caused by
alkalinity present in water.
Surface water treatment rule promulgated?
June 29, 1989.
Daily usage of chlorine gas checked by chlorine scale.
N/A
When a permit is required for entry to a confined space who may sign the permit?
Competent person.
A main break may cause low water pressure in the distribution system, which in turn may result in contamination of the water system by?
Backsiphonage.
What is the primary health risk for volatile organics?
Cancer.
Primary origin of fecal coliform in water supply?
Fecal contamination by animal waste.
What is primacy?
Primary authority for implementation and enforcement of drinking water regulations.
The presence of coliform in drinking water indicates
the potential presence of pathogens.
If raw water turbidity changed from 10 to 300 turbidity units and the finished water turbidity units went from 0.1 to 1 unit, what is the treatment process having the most impact to correct this is?
Coagulation.
A primary health risk associated with microorganisms in drinking water is
acute gastrointestinal diseases.
A granular material used in filtration process to remove synthetic organic chemicals is
GAC.
What can operator do if iron fouling appears to be a problem in ion exchange softening?
Increase backwash rates.
The peak capacity of a water main is often reduced by?
Tuberculation/CORROSION
The presence of which of the following organism indicates a potential for having pathogens presence in the water?
Coliform.
Carbon dioxide in water causes what problem?
Corrosion.
Sodium Hypochlorite is fed by?
Hypochlorinator.
Which valve is most suitable for throttling flows?
Globe, plug, eccentric, butterfly.
If two pumps of the same flow capacity and pressure rating are piped in series what would be the result?
Double the head.
The two components of a mechanical seal for a pump must match properly
N/A
After chlorine demand is satisfied what is the remaining chlorine called?
Residual.
Which treatment technology can be used to achieve compliance with a volatile organic chemical maximum contaminant level (MCL)?
Point-of entry (POE) devices.
When chlorine gas leaks from the cylinder assembly, the use of water may cause to form and exacerbate the leak?
Hydrochloric acid.
The normal filtration rate of a rapid sand filter is?
2-10 gpm/sq ft.
The normal filtration rate of a slow sand filter is?
0.015 to 0.15 gpm/sq ft.
Bi-carbonate alkalinity occurs at what pH?
Between pH 4.5-8:3.
Where is a wear ring located?
Between the housing and the impeller.
What is the purpose of a wear ring?
Plug internal leakage.
Plug internal leakage.
Recarbonation.
What is a disadvantage of returning sludge to the primary mix?
May increase magnesium content.
Below pH 8.3, what doesn't exist?
P Alkalinity.