Water Treatment Operator Level 2 Practice Exam

The main application of potassium permanganate as an oxidant in water treatment is to _____.

Control odor and taste.

How does an inclined plate settler differ from a conventional clarifier?

Requires a smaller footprint than a conventional clarifier.

In water treatment systems what operational event occurs when lime slurries contact surfaces?

Calcium carbonate precipitates and coats surfaces.

What percentage of available chlorine does calcium hypochlorite contain for disinfection?

65-70%.

What do flocculation and coagulation involve in water treatment?

Mechanical and chemical processes.

What benefit does a bacterial slime layer provide on pipe surfaces?

Prevents calcium carbonate deposition.

What causes air binding in water treatment filters?

Air pressure greater than atmospheric pressure.

What are the two categories of corrosion in water systems?

Uniform and localized corrosion.

What factors determine the optimal pH for oxidizing iron and manganese in water treatment?

Precipitate solubility.

How does inadequate flocculation time impact floc formation?

Decreases floc formation.

What compound precipitates when excess lime softening removes magnesium ions?

Magnesium hydroxide.

What effect does preoxidation have on water treatment processes?

Improves filtration, flocculation, and sedimentation.

When water is stabilized with sulfuric acid, what noncarbonate hardness chemical is created?

CaSO₄.

At what CO₂ levels does iron removal become more difficult?

5-10 mg/L.

What is the difference between true and apparent color in water quality measurement?

True color is after turbidity removal, apparent color is due to suspended matter.

Why is monomedium filter media deeper than conventional media in water treatment?

To compensate for coarser media texture.

What is a disadvantage of using chlorine dioxide as a disinfectant?

Imparts an unpleasant taste

What operational factor affects floc development in a treatment plant?

Insufficient flocculation time.

What happens if quicklime gets moist during corrosion control?

Heat is generated, potentially igniting combustible materials.

What causes air binding in a filter?

Terminal head loss.

What variable enhances the effectiveness of disinfection?

Higher chlorine concentrations.

How can lime be purchased in water treatment?

As CaOH, called hydrated lime.

How does high pH affect hypochlorous acid dissociation?

Causes faster dissociation into chlorate ions and water.

When should super-chlorination be used at a water utility?

After installing new pipeline sections.

How can operators address slower floc formation when using alum in cold water?

Increase alum dosage.

What are common coagulants in water treatment?

Alum.

How is chlorine demand calculated?

By subtracting chlorine residual from chlorine dose.

How can THM formation be minimized in water treatment?

Avoid pre-chlorination of water.

What carbonate hardness chemical precipitates during lime-softening besides CaCO₃?

Magnesium hydroxide.

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What is the definition of breakthrough in water filtration?

The point when filtration stops removing impurities.

How can mud balls on filter media surfaces be removed?

Use a surface wash on the filter unit.

What is the expected result when coliform bacteria grow in lactose or brilliant bile tryptose broth at 35°C for 24-48 hours?

Gas production in the broth.

What type of lab equipment resists high heat, temperature changes, and chemical attacks?,

Porcelain crucibles.

What type of household detergent is preferred for cleaning labware?

Nonphosphate liquid detergent.

Where should an operator avoid collecting water samples to prevent contamination?

Taps with hose threads or sill cocks.

What material is recommended for manufacturing sample glass bottles?

Borosilicate.

What category do bacteria belong to in water treatment?

Colloidal particles.

What is humic acid's role in water analysis?

An organic precursor that reacts with disinfectants or forms colored compounds.

How do heterotrophic organisms interact with organic matter in water treatment plants?

Consume organic matter for energy and growth.

What is the purpose of using lactose or brilliant bile tryptose broth?

To detect gas production by coliform bacteria.

What is the recommended lid position while collecting a bacteriological sample?

Cap threads face downward during sample collection.

How does water temperature affect dissolved oxygen concentration?

Colder water holds more dissolved oxygen.

What happens when natural organic matter reacts with chlorine?

Trihalomethanes form.

What does a dissolved oxygen test predict in water quality?

Presence of anoxic conditions.

What causes pink water in water treatment systems?

Overdosing of potassium permanganate.

Under what conditions is chlorine dioxide stable?

Absence of light and low temperatures.

What monitoring procedure determines the efficiency of ultraviolet disinfection treatment?

Monitoring other than residual monitoring.

What is the relationship between pressure difference and flow rate in a pressure-differential meter?

Directly proportional.

What safety equipment is required when changing chlorine cylinders or 1-ton containers?

Personal protective respirator.

What is the primary purpose of mechanical seals?

Control process fluid leakage.

What is the operational purpose of the graded gravel layer in a multimedia filter?

Support the sand bed and underdrain system.

Why are vibrators installed in fluoride dry feeders for larger facilities?

To increase feed accuracy.

What chlorine gas solution controller is best for stable chlorine demand with minimal adjustment needs?

Flow proportional controller.

What is a characteristic of chlorine gas?

Pungent smell.

What material is used to line pipes for corrosive chlorine solutions?

PVC.

How often should raw water fluoride content be analyzed?

Weekly.

How often should gravel bed downflow fluoride saturator tanks be cleaned?

Every three months.

What is the recommended frequency for inspecting screen equipment for corrosion?

Monthly.

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What happens when zebra mussels die off in a water body?

Decomposition releases large quantities of phosphates.

What geological formation has the lowest vulnerability to microbiological contamination?

Siltstone.

What occurs under anaerobic conditions when organic matter decomposes?

pH decreases due to hydrogen sulfide gas production.

What processes neutralize the negative charges on colloids to form flocs?

Coagulation.

What chemical is commonly used to control Asiatic clams and zebra mussels?

Sodium hypochlorite.

What defines the radius of influence in groundwater?

The distance from a well bore to where water table lowering ends.

What can cause elevated nitrate levels in groundwater?

Over-fertilization of land.

What minerals are commonly found in groundwater?

Manganese and iron.

What is a common issue in the epilimnion layer of a stratified reservoir?

Algae growth.

What causes thermal stratification in surface water?

Warmer surface water temperatures.

What is a pathogen?

A microorganism capable of causing disease in a host.

What processes neutralize the negative charges on colloids to form flocs?

Coagulation.

At what iron level do customers typically notice a taste?

0.5 mg/L.

Who provides testing for point-of-entry or point-of-use devices?

NSF International.

How effective is ultraviolet light against Cryptosporidium?

Ultraviolet light eliminates Cryptosporidium effectively.

What are the MCLG and MCL values for E. coli under the Revised Total Coliform Rule?

MCLG and MCL of zero.

What is required under the Long-Term 1 Enhanced Surface Water Treatment Rule?

Achieve a 2-log reduction in Cryptosporidium.

What gas emitted by storage batteries requires proper ventilation?

Hydrogen.

What is the treatment for soda ash dust in the eyes?

Flush with warm water for 15 minutes.

What characterizes absolute ownership allocation of groundwater?

Property owners may use water from their land.

What waterborne disease is targeted by the Surface Water Treatment Rule?

Legionella.

What is the significance of chain-of-custody records in laboratories?

Ensures compliance with the Safe Drinking Water Act.

What does the Total Coliform Rule require for distribution point sampling?

Monthly sampling at all distribution points.

What approach does the Total Coliform Rule use?

Qualitative (presence or absence).

What protective equipment is mandatory for chlorine gas exposure?

Respirator (SCBA).

How are customers notified of serious drinking water problems?

Through public notice.

What contaminant causes Blue Baby Syndrome?

Nitrate.

What problems are caused by blue-green algae in water?

Clogged filters, slime, and odors or taste.

How does natural organic matter affect the production of THMs during chlorination?

High concentrations increase THM production.

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How are manganese greensand beds regenerated in water treatment?

Backwashed with potassium permanganate solution.

What is the ideal alkalinity-to-alum ratio for effective coagulation?

0.5:1.

What processes are commonly used for effective water treatment?

Filtration, sedimentation, and coagulation.

What are the two broad classes of corrosion in water systems?

Uniform and localized corrosion.

What is the anticipated electrical charge of a coagulant?

Positive.

What is another name for caustic soda?

Sodium hydroxide.

What underdrain system includes a gravel or sand base to prevent clogging?

Perforated tile bottom.

What is the USEPA Stage 1 maximum contaminant level for TTHMs?

80 μg/L.

What is the most reliable method for detecting small chlorine leaks?

Chlorine leak detector.

What corrosion inhibitors are commonly used in water treatment?

Silicates and polyphosphates.