Dylan's Class 2

Molarity is the number of: a. gram equivalent weights of solute per liter of solution b. gram atomic weight per oxidation number c. moles of solute per kilogram of solvent d. moles of solute per liter of solution

d

Which conventional treatment step is eliminated by direct filtration? a. oxidation b. aeration c. flocculation d. sedimentation

d

Which of the following is a common mistake that operators make in regard to flocculation units? a. excessive flocculation time b. lack of food-grade NSF-approved grease on the flocculator bearings c. keeping the mixing energy the same in all flocculation units d. too short a flocculation time

a

In the volume formula, how is volume calculated?

area of surface x third dimension

A solution consists of two parts: a solvent and a: a. diluent b. solute c. concentrate d. suspension

b

As solids settle to the bottom of the sedimentation basin: a. tank pressure is reduced b. a sludge layer develops c. movement of sediment accelerates d. water pH decreases

b

The first step in calculating percent by weight of an element in a compound is to determine the: a. percent by weight b. molecular weight c. chemical equation d. coefficient

b

The lower the ____, the more difficult it is to form a proper floc. a. temperature b. turbidity c. pH d. alkalinity

b

Water being served to the public for a population greater than 3,300 must not have a disinfectant residual entering the distribution system below ____ for more than 4 hours a. 0.1 mg/L b. 0.2 mg/L c. 0.3 mg/L d. 0.4 mg/L

b

What is the MCL for haloacetic acids (HAA5)? a. 0.040 mg/L b. 0.060 mg/L c. 0.080 mg/L d. 0.100 mg/L

b

"CaCO2" is the ______ of calcium carbonate. a. chemical symbol b. atomic formula c. chemical formula d. chemical equation

c

A chemical metering pump is pumping 26.3 gal/day. How many mL/min is this? a. 47.6 mL/min b. 60.8 mL/min c. 69.1 mL/min d. 75.4 mL/min

c

Ferric sulfate has which advantage over aluminum sulfate (alum) a. less staining characteristics b. less cost c. more dense floc d. not as corrosive

c

Find the detention time in hours for a clarifier that has an inner diameter of 112.2 ft and a water depth 10.33 ft if the flow rate is 7.26 mgd. a. 2.10 hr b. 2.14 hr c. 2.52 hr d. 2.96 hr

c

What is the major cause of short-circuiting in a sedimentation basin? a. Open basins that are subject to algal growths and thick slime growths on the side of the basin b. Basins without a wind break c. Poor inlet bassling d. Density currents

c

What is the optimal pH range for the removal of particulate matter when using alum as a coagulant? a. 4.5 to 5.7 b. 5.8 to 6.5 c. 6.5 to 7.2 d. 7.3 to 8.1

c

Where are the sampling point(s) located for required sampling of turbidity in a community water system? a. at representative points within the distribution system b. 75% at locations representative of population distribution and 25% at the farthest points in the distribution system c. at point(s) where water enters the distribution system, including all filter effluents if a surface water treatment plant d. at effluents of all filters if a surface water treatment plant, at entry points to the distribution system, and at locations representative of population distribution

c

Which of the following is the layer of solids and biological growth that forms on the top of a slow sand filter? a. biosolids film b. bio-carbonated scale layer c. schumtzdecke d. saprophytic layer

c

Dissolved-air flotation is particularly good for removing a. sulfides b. inorganics c. maganese and iron d. algae

d

What is the MCLG for substances that are suspected carcinogens?

zero

If filter run times between backwashes are long (one week) because high quality (low turbidity) water is being applied to the filters, which problem could still arise? a. Mudball formation b. Air binding and formation of mudballs c. Extended backwashing due to media becoming too compacted d. Floc breakthrough

d

If enteric disease-casing protozoans have been found in the effluent of a water plant, which of the following is the most probable solution? a. where possible, use powdered activated carbon (PAC) throughout the water plant; backwashing filters will remove the PAC. b. Use PAC only in the sedimentation basin; backwashing the filters will remove the PAC. c. Use the multibarrier approach - coagulation, flocculation, sedimentation, and filtration. d. Superchlorinate the water plant.

c

What is the action level for copper? a. 0.5 mg/L b. 1.0 mg/L c. 1.3 mg/L d. 1.8 mg/L

c

A water treatment plant has an emergency shutdown. How many water supply hours are left in a 119.8 ft diameter tank given the following data? - Tank's water level = 27.6 ft - Water cannot go below 16.0 ft at any time to comply with fire control - Water usage averages 48.3 gpm a. 33.7 hr b. 35.0 hr c. 35.4 hr d. 36.2 hr

a

Conventional sedimentation has a ______ removal of Cryptosporidium oocytes a. less than 0.5-log b. 0.5-log c. 1.0-log d. 2.0-log

a

Jar test results are expressed in a. milligrams per liter b. gallons per day c. whatever unit the treatment system has decided to use d. parts per million

a

Under the Surface Water Treatment Rule, disinfection residuals must be collected at the same location in the distribution system as a. coliform samples b. total trihalomethanes c. disinfection by-products d. alkalinity, conductivity, and pH for corrosion studies

a

What term refers to the number of equivalent weights of solute per liter of solution? a. normality b. equivalent weight c. molecular weight d. coefficient

a

Which forces will pull particles together once they have been destabilized in the coagulation-flocculation process? a. van der Waals forces b. Zeta potential c. Ionic forces d. Quantum forces

a

Gravel displacement in a filter bed from backwash rates with too high of a velocity could eventually cause a. compaction of the filter media b. loss of media into the backwash troughs c. a sand boil d. bed shrinkage

c

If a spherical tank is 20 ft in diameter, what is its capacity?

4,187 ft cubed

The chemical formula for calcium hydroxide (lime) is Ca(OH)2. Determine the number of atoms of each elements in a molecule of the compound.

Ca- 1 atom O- 2 atoms H- 2 atoms

What regulation is designed to reduce the risk of exposure to fecal contamination that may be present in public water systems that use ground-water sources?

GWR

Which regulation is designed to limit human exposure to harmful organisms, including cryptosporidium, by promoting achievement of particle and turbidity removal targets for surface water treatment systems?

IESWTR

Which regulation is designed to promote routine surveillance of distribution system water quality to search for contamination from fecal matter and/or disease-causing bacteria?

TCR

What is the formula for calculating the area of a circle?

(0.785)(D squared)

You need to prepare 25 gal of a solution with 2.5 percent strength. Assume the solution will have the same density as water: 8.34 lb/gal. How many pounds of chemical will you need to dissolve in the water?

5.21 lb of chemical

The equation of the reaction between calcium carbonate (CaCO3) and carbonic acid (H2CO3) is shown. if 10 lbs of H2CO3 is used in the reaction, how many pounds of CaCO3 will react with the H2CO3?

16.1 lbs

How much time is required to develop heavy floc particles during the flocculation process?

30 min

How much water should be added to 80 mL of a 2.5N solution of H2CO3 to obtain a 1.8N solution of H2CO3?

31.11 mL