Water Treatment Class D Study Guide Exam - Prof. Authur, Exams of Water and Wastewater Engineering

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Test Practice Questions & Answers

The two most important factors impacting the effectiveness of chlorination are? - ANS ✔ - Concentration of chlorine and contact time

The treatment process that controls corrosion or scaling is known as? - ANS ✔ - stabilization

Permanganate reactions are highly dependent upon? - ANS ✔ - pH

It is hardest to kill the organism that causes which of the following illness? - ANS ✔ - Cryptosporidiosis

Disinfection of water wells with free chlorine requires exposure for___ at a concentration of___. - ANS ✔ - 12 to 24 hours; 50mg/L

Detention time in flocculation basins are usually designed to provide for? - ANS ✔ - 15 to 45 min.

Alum works best in a pH range of - ANS ✔ - 5.8-7.5.

Which statement is true concerning colloidal particles? - ANS ✔ - Colloidal particles are so small that gravity has little effect on them

Which natural electrical force keeps colloidal particles apart in water treatment? - ANS ✔ - zeta potential.

The zeta potential measures the number of excess found on the surface of all particular matter. - ANS ✔ - Electrons.

Which device collects the settled water as it leaves the sedimentation basin? - ANS ✔ - Effluent launder

Test Practice Questions & Answers

In solid-contact basins with fairly constant water quality parameters, how often should the solids concentration be determined? - ANS ✔ - At least twice per day

The definition of decant is? - ANS ✔ - to draw off the liquid from a vessel of any size without stirring up the bottom sediment

How often should sedimentation basins with mechanical sludge removal equipment be drained and inspected? - ANS ✔ - once a year

Which is the most important reason to reduce turbidity? - ANS ✔ - To remove pathogens

Which is the filtration flow rate through a manganese greensand pressure filter at 10•C? - ANS ✔ - 2 to 3 got/ft

When a filter is ripening - ANS ✔ - it is becoming more efficient in particle removal

Virgin greensand can be regenerated by soaking the filter bed for several hours in a solution of chlorine containing - ANS ✔ - 100mg/L Cl

Which role does the action of straining of suspended particles play during filtration? - ANS ✔ - minor

The turbidity of settled water before it is applied to the filters (post sedimentation process) should always be kept below - ANS ✔ - 1 to 2 ntu

Which precipitates can foul a cation exchange resin? - ANS ✔ - Iron and manganese

Which process works best for sequestering manganese? - ANS ✔ - Polyphosphates and chlorine

Test Practice Questions & Answers

When should polyphosphates used for sequestration of iron and manganese from a well be injected into the process? - ANS ✔ - Right after the water leaves the well

Re-carbonation is - ANS ✔ - a. adding CO2 to the water

In the ion-exchange softening process, once the resin can no longer soften water it must be? - ANS ✔

• regenerated

Under no circumstances should a composite sample be collected for which type of analysis? - ANS ✔

• Bacteriological

The number of monthly distribution systems chlorine residual samples required is? - ANS ✔ - Based on population

Which is (are) the ideal indicator for pathogens? - ANS ✔ - Coliform group bacteria

When one substance is dissolved in another and will not settle out, which is the product called? - ANS ✔ - A solution

Acids, bases, and salts lacking carbon are? - ANS ✔ - inorganic compounds

The main purpose of mechanical seals is to - ANS ✔ - Control water leakage from the stuffing box

The purpose of packing is to - ANS ✔ - Control water leakage along the pump's shaft

Which part of a pump houses the packing or mechanical seal? - ANS ✔ - stuffing box

Which is the only type of pump that can be operated against a closed valve? - ANS ✔ - Centrifugal pump

Test Practice Questions & Answers

Which is a principal problem associated with preliminary treatment screening? - ANS ✔ - clogging

Which is the most important thing to consider in the automatic startup after power failure? - ANS ✔

• Operator safety

At which range of temperatures will fusible plugs on chlorine cylinders melt? - ANS ✔ - 157 to 162

When a chlorine cylinder or container is changed, a new gasket should be used - ANS ✔ - every time

Which is the best type of gasket to use when connecting a chlorine cylinder or container to the chlorine feed system? - ANS ✔ - Lead gasket

Which part of the human body is the most vulnerable to allowing microorganisms to enter it? - ANS ✔ - Eyes

The organisms used to indicate the likelihood that pathogenic bacteria may be present are - ANS ✔ - coliform bacteria

Which adverse effects does the secondary contaminant manganese have? - ANS ✔ - Discolored laundry and changed taste of water, coffee, tea, and other beverages

In general, which causes an increase in taste and odors when natural waters lack dissolved oxygen?

• ANS ✔ - Anaerobic decomposition

A physical property, as opposed to a chemical property, important to water treatment is? - ANS ✔ - turbidity

Which are the two principal chemicals that caused water hardness? - ANS ✔ - Calcium and magnesium

Test Practice Questions & Answers

A watercourse that flows continuously at all times of the year is called? - ANS ✔ - Perennial stream.

During the night, algae causes the pH of the water to? - ANS ✔ - Decrease

Which of the following contributes to the creation of algae blooms? - ANS ✔ - Increased nutrients

Which of the following is found mainly in groundwater sources and forms a precipitate when oxidized? - ANS ✔ - Iron

The Riparian Doctrine is something called the? - ANS ✔ - Rule of Reasonable Sharing

Which of the following terms is defined as the killing or inactivation of pathogenic organisms in water? - ANS ✔ - Disinfection

Free Chlorine residual values are based on a contact time of at least? - ANS ✔ - 10 min

What is the typical strength of calcium hypochlorite, i.e., available chlorine range? - ANS ✔ - 65%- 70%

The iron content of a raw water is 1.81 mg/L. What is the percent removal if the finished water contains 0.11 mg/L iron - ANS ✔ - 94%

Which of the following chemicals will raise pH? - ANS ✔ - Soda ash, Lime and Caustic soda also raise the pH

Which of the following should be used by an operator to test for residual chlorine? - ANS ✔ - DPD

Which one of the following is a major part of a turbid meter? - ANS ✔ - Light source

Test Practice Questions & Answers

Which of the following parameters is used to indicate the clarity of water? - ANS ✔ - Turbidity

PH is a measure of? - ANS ✔ - Hydrogen ion concentration

After chlorination, the free chlorine residual includes - ANS ✔ - OCl- and HOCl

After initial full-service operation, grease-lubricated bearings should be regressed at what frequency? - ANS ✔ - 3 to 6 months

Check valves are used to prevent? - ANS ✔ - Water from flowing in two directions

If only two rings of packing are used in the stuffing box, the joints should be - ANS ✔ - Staggered

Which of the following is a primary function of couplings? - ANS ✔ - Compensate for alignment changes

What is the correct formula for determining watts? - ANS ✔ - Watts= (amps) (volts)

Opening the discharge valve one full turn on a chlorine cylinder will... - ANS ✔ - Permit Maximum Discharge

What of the following best defines the term “C value"? - ANS ✔ - Number that describes the smoothness of the interior of a pipe

Tubercles can form on which of the following types of pipe? - ANS ✔ - Ductile iron

Which of the following is a primary indicator of bearing failure? - ANS ✔ - Noise from pump

Test Practice Questions & Answers

What is the feet of head at the discharge side of a pump that is pumping against a pressure of 100 psi? - ANS ✔ - 231ft (100 psi*2.31ft-head/psi = 231 ft-head)

Which of the following diseases is capable of being transmitted by water? - ANS ✔ - Typhoid

When any piece of electrical equipment is being worked on, the circuit breaker should be - ANS ✔ - De-energized and locked out

If ammonia vapor is passed over a chlorine leak in a cylinder valve, the presence of the leak is indicated by a: - ANS ✔ - white cloud

Which of the following directly impacts the treatment of drinking water? - ANS ✔ - Safe Drinking Water Act

Corrosive water acting on a customer's plumbing may cause which of the following metals to enter their drinking water? - ANS ✔ - Lead

Which of the following is the most common water complaint? - ANS ✔ - Objectionable taste and/ or odor

According to surface water treatment rule requirements, Systems serving a population greater than 500 persons must sample the filtered water for turbidity every - ANS ✔ - 4 hours

For surface water systems without filtration, the Surface Water Treatment Rule requires public water systems to - ANS ✔ - maintain a C x T value above the minimum value

Surface water systems must treat, at a minimum, for - ANS ✔ - Coliform bacteria and turbidity

What US agency establishes drinking water standards? - ANS ✔ - USEPA