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50 Cards in this Set
- Front
- Back
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Immediately before breakpoint chlorination occurs, which chemical species are destroyed? A. Aromatic hydrocarbons B. Aromatic hydrocarbons and aliphatic hydrocarbons C. Ammonia and chloroorganics D. Chloroorganics and chloramines |
D. Chloroorganics and chloramines |
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Which is the most effective disinfectant for inactivating viruses? A. Hypochlorite ion B. Diatomic iodine C. Chloramines D. Chlorine dioxide |
D. Chlorine dioxide |
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Which is the most effective disinfectant for inactivating protozoan cysts? A. Chloramines B. Hypochlorous acid C. Ozone D. Bromine |
C. Ozone |
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Which chemical oxidant would be most effective in removing color and for controlling tastes and odors? A. Ozone B. Potassium permanganate C. Chloramines D. Chlorine |
A. Ozone |
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Which chemical oxidant is the weakest? A. Oxygen B. Ozone C. Potassium permanganate D. Chlorine dioxide |
A. Oxygen |
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Why can hypochlorous acid (HOCl) penetrate bacterial surfaces better than hypochlorite ion (OCl-)? A. because it is a proton donor B. Because it is an acid C. Because it is a smaller molecule than OCl- despite having a hydrogen atom; the hydrogen atom helps compact the molecule D. Because it is neutral |
D. Because it is neutral |
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Which chlorine compound will produce the least detectable chloronous taste and odor? A. Hypochlorous acid B. Monochloramine C. Dichloramine D. Nitrogen trichloride |
B. Monochloramine |
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Which type of pumps would be the most economical to use if large volumes of sodium hypochlorite were required? A. Chemical feed pumps using piston rods B. Chemical feed pumps using plunger drives C. Centrifugal pumps D. Solenoid-operated pumps |
C. Centrifugal pumps |
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A disadvantage to using chloramines is A. their vulnerability to nitrification B. that they cannot penetrate biofilms in the distribution system C. their propensity to form trihalomethanes D. that their residual persistence in the distribution system is low |
A. their vulnerability to nitrification |
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Where is the best place to add corrosive inhibitors such that disinfection can take place under more advantageous conditions at a conventional water treatment plant? A. Rapid mix basin B. pre-filter C. pre-clearwell D. post clearwell |
D. post clearwell |
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Which method can be used to control scaling but is never used to control corrosion? A. Chelation B. Controlled CaCO3 scaling C. Polyphosphate addition D. pH and alkalinity adjustment with lime |
A. Chelation |
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How much more soluble is ozone in water than oxygen? A. 7.6 times B. About 10.0 times C. 12.0 times D. 20.0 times |
D. 20.0 times |
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Which is the most effective ratio of hydrogen peroxide to ozone? A. 1:2 B. 2:5 C. 1:3 D. 1:4 |
A. 1:2 |
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Which is the chlorine demand of nitrite? A. 2.0 parts chlorine to 1 part nitrite B. 2.5 parts chlorine to 1 part nitrite C. 4.0 parts chlorine to 1 part nitrite D. 5.0 parts chlorine to 1 part nitrite |
D. 5.0 parts chlorine to 1 part nitrite |
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A sodium hypochlorite solution at room temperature will lose which percentage of its available chlorine content per month? A. 1 to 2% B. 2 to 4% C. 4 to 6% D. 6 to 8% |
B. 2 to 4% |
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When supplied with air, ozone generators will produce about A. 2% ozone B. 5% ozone C. 7% ozone D. 12% ozone |
A. 2% ozone |
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Which method for chlorine dioxide generation is most likely to have substantial amounts of chlorine in solution? A. Add chlorine to water, then this water to sodium citrate and sodium chlorate B. Add chlorine to water, then this to hydrochloric acid and sodium chlorate C. Inject chlorine gas under vacuum into a stream of chlorite solution D. Add hydrochloric acid to a chlorite solution |
B. Add chlorine to water, then this to hydrochloric acid and sodium chlorate |
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Which chemical used for stabilization of potable water is a bacterial nutrient? A. Polyphosphate B. Lime C. Soda ash D. Sodium bicarbonate |
A. Polyphosphate |
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Once formed, hypochlorous acid instantaneously establishes equilibrium as follows: HOCl <-> H+ + OCl- This equilibrium reaction at 20 degrees C has which characteristic? A. It contains 50% of HOCl and OCl- at a pH of 7.3 B. The reaction depends on concentration C. It responds slowly to pH changes D. It is completely reversible |
D. It is completely reversible |
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Ultraviolet light used in disinfection is generated by mercury or A. germanium B. antimony C. cesium D.cadmium |
B. antimony |
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The production of earthy-musty compounds, geosmin, and 2-methylisoborneol (MIB) by cyanobacteria are difficult to remove except when using A. lime B. ozone C. aeration D. filtration |
B. ozone |
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Which chemical oxidant would be most effective for removing synthetic organics? A. Oxygen B. Chlorine C. Chloramines D. Chlorine dioxide |
D. Chlorine dioxide |
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The advantage to using the oxidant oxygen is that it A. is non-corrosive B. has no by-products C. causes small amount of scaling problems D. is a strong oxidant |
B. has no by-products |
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Which is the commercial purity of fluorosilicic acid A. 20 to 30% B. 20 to 40% C. 30 to 40 % D. 35 to 48% |
A. 20 to 30% |
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Which type of fluoride chemical should be used in down flow saturators? A. Tablets of sodium fluorosilicate B. Granular sodium silicofluoride C. Crystalline sodium fluoride D. Powered sodium fluoride |
C. Crystalline sodium fluoride |
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The decomposition products of sodium hypochlorite into chlorate and O2 would be caused by which factors? A. Temperature B. Metallic impurities C. UV light D. pH |
C. UV light |
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Which are the only two metals that can contact sodium hypochlorite; all other metals must be eliminated from storage vessels, piping, valves and feed equipment? A. Titanium and tantalum B. Titanium and germanium C. Vanadium and germanium D. Vanadium and selenium |
A. Titanium and tantalum |
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Sites that require chlorine vaporizers typically have feed rates that exceed A. 450 lb/d B. 800 lb/d C. 1,000 lb/d D. 2,000 lb/d |
D. 2,000 lb/d |
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The deterioration of elastomeres by chloramines is enhanced by A. higher pH B. lower pH C. higher temperatures D. lower temperatures |
C. higher temperatures |
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Most water treatment systems can limit nitrification by A. Maintaining a pH of 7.0 to 7.5 B. maintaining a chlorine to ammonia-nitrogen ratio between 4.5:1 and 5.0:1 C. limiting excess free ammonia to below 0.5 mg/L nitrogen D. maintaining temperature between 18 and 28C |
B. maintaining a chlorine to ammonia-nitrogen ratio between 4.5:1 and 5.0:1 |
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If the percentage of chlorine delivered to a water treatment plant in liquid form is 12.5%, which chemical is it most likely to be? A. Calcium hypochlorite B. Sodium hypochlorite C. Chlorine D. Chlorine dioxide |
B. Sodium hypochlorite |
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How many steps are in the coagulation process? A. 3 B. 4 C. 5 D. 6 |
A. 3 |
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Polymers used as flocculants are A. water-soluble inorganic electrolytes B. water-insoluble organic polyelectrolytes C. water-insoluble inorganic electrolytes D. water-insoluble organic polyelectrolytes |
D. water-insoluble organic polyelectrolytes |
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Which is the zeta potential? A. Electrical charge on a suspended particle B. Electrical resistance of a suspended particle C. Electrical potential of a suspended particle D. Electrical charge of a suspended particle as it relates electrochemically to the coagulate being used |
A. Electrical charge on a suspended particle |
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All colloids are A. sols B. hydrophobic C. electrically charged D. emulsoids |
C. electrically charged |
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Colloidal particle movement and aggregation caused by thermal energy is called A. orthokinetic flocculation B. parakinetic dynamism C. Brownian movement D. thermodynamic flocculation |
C. Brownian movement |
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When used with alum, which chemical improves coagulation? A. Ferric chloride B. Ferric Sulfate C. Sodium aluminate D. Aluminum sulfate |
C. Sodium aluminate |
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The coagulant alum reacts with natural alkalinity in the water forming A. aluminum hydroxide B. aluminum carbonate C. aluminum bicarbonate D. aluminum oxide |
A. aluminum hydroxide |
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When ferric coagulants react with natural alkalinity in the water they form A. ferric hydroxide B. ferric carbonate C. ferric bicarbonate D. ferric oxide |
A. ferric hydroxide |
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Detention time in mechanical mixers usually ranges from A. 5 to 15 seconds B. 15 to 45 seconds C. 1 to 2 minutes D. 2 to 4 minutes |
B. 15 to 45 seconds |
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The aluminum ions in alum neutralize the negatively charged particles in the raw water in about A. 1 to 2 seconds B. 3 to 5 seconds C. 5 to 8 seconds D. 5 to 12 seconds |
A. 1 to 2 seconds |
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Suspended and colloidal solids found in natural waters are usually A. positively charged B. negatively charged C. neutral D. polyionic |
B. negatively charged |
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After the oxidation treatment, H2S in the water turns a milky-blue color because of elemental sulfur (solid sulfur). Which is the best procedure to remove this sulfur? A. Adsorption B. Sedimentation C. Coagulation and filtration D. Lime-soda ash softening |
C. Coagulation and filtration |
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Particles will stay in suspension as long as the A. ionic forces are stronger than the van der Waals forces B. zeta potential is stronger than the van der Waals forces C. van der Waals forces are stronger than the ionic forces D. van der Waals forces are stronger than the zeta potential |
B. zeta potential is stronger than the van der Waals forces |
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The most probable effective ratio of the coagulants aluminum sulfate to hydrated lime is A. 1:1 aluminum sulfate to hydrated lime B. 3:1 aluminum sulfate to hydrated lime C. 5:1 aluminum sulfate to hydrated lime D 6:1 aluminum sulfate to hydrated lime |
B. 3:1 aluminum sulfate to hydrated lime |
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Which should the "tip speed" of the flocculator be in water, assuming the water is not extremely cold? A. 0.2 ft/sec B. 0.5 ft/sec C. 1.0 ft/sec D. 2.0 ft/ sec |
C. 1.0 ft/sec |
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Coagulants consisting of trivalent ions are how much more effective than bivalent ions? A. 50 to 60 times B. 100 to 120 times C. 200 to 250 times D. 1000 times |
A. 50 to 60 times |
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when tip velocities of the impellers reach speeds greater than _____ localized shearing of floc occurs A. 6.0 fps B. 8.0 fps C. 10.0 fps D. 10.5 fps |
B. 8.0 fps |
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In the flash mixing process, which type of rapid mixing system has the most significant head loss? A. mechanical mixers B. Static mixers C. Pumps and conduits D. Baffled chambers |
B. Static mixers |
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When these types of chemicals are used, flash mixing becomes less critical, but through mixing (flocculation) remains very important. A. Ferric or ferrous chloride B. Aluminum sulfate C. Lime, soda ash, or caustic soda D. Polymers |
D. Polymers |
