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Answers to More M&M Today's Questions

Wastewater Treatment, Water Treatment, Distribution, and Collection

How about some practice calculating pump capacities?

Formula SWD - Min Depth (L)(W)(H)   Vol Time gpm x 1440 gpd 1,000,000 gpm x 7.5 60
L, ft W, ft SWD, ft Min Depth, ft Draw-down, ft Volume, cf Draw-down Time, min Flow, gpm Flow, gpd Flow, MGD Flow, cfs
20 10 12 4 8 1,600 30 400 576,000 0.576 0.889
30 15 14 5 9 4,050 35 868 1,249,714 1.2497 1.93
50 25 16 6 10 12,500 40 2,344 3,375,000 3.375 5.21
80 40 18 7 11 35,200 45 5,867 8,448,000 8.448 13.04
100 50 20 8 12 60,000 50 9,000 12,960,000 12.96 20

 

How about some more practice calculating chlorine dosages, residuals, and demands in mg/L and lbs?

 

Day Flow Chlorine
MGD Dose Residual Dose Residual Demand
LBS mg/L mg/L LBS mg/L LBS
1 0.61 8.38 0.50 1.65 2.54 1.15 5.84
2 0.59 7.43 0.50 1.51 2.46 1.01 4.97
3 0.58 7.67 0.50 1.59 2.42 1.09 5.25
4 0.54 6.93 0.50 1.54 2.25 1.04 4.68
5 0.80 9.02 0.50 1.35 3.34 0.85 5.68
6 0.82 9.92 0.50 1.45 3.42 0.95 6.50
7 0.53 6.48 0.50 1.47 2.21 0.97 4.27
8 0.52 6.56 0.50 1.51 2.17 1.01 4.39
9 0.60 7.83 0.50 1.56 2.50 1.06 5.33
10 0.51 6.76 0.50 1.59 2.13 1.09 4.63
11 0.57 6.75 0.50 1.42 2.38 0.92 4.37
12 0.75 8.48 0.50 1.36 3.13 0.86 5.35
AVERAGE 0.62 7.68 0.50 1.50 2.58 1.00 5.11
MAXIMUM 0.82 9.92 0.50 1.60 3.42 1.10 6.50
MINIMUM 0.51 6.48 0.50 1.40 2.13 0.90 4.27

 

How about some practice calculating chlorine dosages, residuals, and demands in mg/L and lbs?

 

Day Flow Chlorine
MGD Dose Residual Dose Residual Demand
LBS mg/L mg/L LBS mg/L LBS
1 61 838 0.5 1.6 254 1.1 584
2 59 743 0.5 1.5 246 1.0 497
3 58 767 0.5 1.6 242 1.1 525
4 54 693 0.5 1.5 225 1.0 468
5 80 902 0.5 1.4 334 0.9 568
6 82 992 0.5 1.5 342 1.0 650
7 53 648 0.5 1.5 221 1.0 427
8 52 656 0.5 1.5 217 1.0 439
9 60 783 0.5 1.6 250 1.1 533
10 51 676 0.5 1.6 213 1.1 463
11 57 675 0.5 1.4 238 0.9 437
12 75 848 0.5 1.4 313 0.9 535
AVERAGE 62 768 0.5 1.5 258 1.0 511
MAXIMUM 82 992 0.5 1.6 342 1.1 650
MINIMUM 51 648 0.5 1.4 213 0.9 427

 

Chlorine ton cylinders at room temperature will deliver gas at a maximum rate of

      150 lb cylinders        Ton Containers

A.  10 pounds per day      100 pounds per day

B.  25 pounds per day      250 pounds per day

C.  40 pounds per day      450 pounds per day

D.  150 pounds per day    2000 pounds per day

The correct answer is C

 

Click on the thumbnail below for the answers for the chart of pump station math for cylindrical tanks.

Click on the thumbnail below for the answers for the chart of pump station math for rectangular tanks.

 

Click on the thumbnail below for the answers for the chart of pipe math.

 

Which of the following valves only permits flow to move in one direction?

A.  Butterfly

B.  Check

C.  Gate

D.  Plug

The correct answer is B

 

The specific gravity of a colloidal solid is very close to 1.  This means that the colloid

A.  Will float within an hour

B.  Will settle within an hour

C.  Won't settle or float

The correct answer is C

 

The specific gravity of settleable solid is

A.  1

B.  Greater than 1

C.  Less than 1

The correct answer is B

 

The specific gravity of a floatable solid is

A.  1

B.  Greater than 1

C.  Less than 1

The correct answer is C

 

The specific gravity of chlorine gas is

A.  1

B.  Greater than 1

C.  Less than 1

The correct answer is B

 

Matching

1.    Calcium

A.  C

2.    Carbon

B.  S

3.    Chlorine

C.  P

4.    Copper

D.  K

5.    Fluorine

E.  O

6.    Iron

F.   Na

7.    Hydrogen

G.  N

8.    Lead

H.  Mg

9.    Magnesium

I.    Ca

10.  Manganese

J.   Cl

11.  Nitrogen

K.  Cu

12.  Potassium

L.   Mn

13.  Sodium

M.   Fe

14.  Oxygen

N.   H

15.  Phosphorus

O.   Pb

16.  Sulfur 

P.   Fl

1.  I

2.  A

3.  J

4.  K

5.  P

6.  M

7.  N

8.  O

9.  H

10.  L

11.  G

12.  D

13.  F

14.  E

15.  C

16.  B

 

Match
1 The units for pressure are A Divided by
2 Head is expressed in B 2.31
3 Velocity is measured in C 0.434 psi
4 Units of flow D psi
5 Pressure times _______ = Head E fps
6 Head __________ 2.31 = Pressure F 1440
7 20 psi =  G 694 gpm
8 1 MGD =  H cfs
9 A head loss of 7 feet = I 3 psi
  J Times
  K ft
  L 46.2 ft
  M Subtracted by

1 = D

2 = K

3 = E

4= H

5 = B

6 = A

7 = L

8 = G

9 = I

 

 

Which of the following is correct?

A.  A is the follower and B is the lantern ring

B.  A is the lantern ring and B is a packing ring

C.  A is a packing ring and B is the lantern ring

D.  A is a packing ring and B is the follower

The correct answer is C.  A is a packing ring and B is the lantern ring

 

pH measures

A.  H+

B.  OH-

C.  O2

D.  Phosphorus

The correct answer is A.  H+  -- pH measures the hydrogen ion concentration

 

The formula for the volume of a rectangular tank is

A.  (Length)(Width)

B.  (0.785)(Diameter2)

C.  (Length)(Width)(Height)

D.  (0.785)(Diameter2)(Height)

The correct answer is C.  (Length)(Width)(Height)

A is the formula for the area of a rectangle

B is the formula for the area of a circle

D is the formula for the volume of a cylinder

 

The formula for the volume of a cylindrical tank is

A.  (Length)(Width)

B.  (0.785)(Diameter2)

C.  (Length)(Width)(Height)

D.  (0.785)(Diameter2)(Height)

The correct answer is D.  (0.785)(Diameter2)(Height)

A is the formula for the area of a rectangle

B is the formula for the area of a circle

C is the formula for the volume of a rectangle

 

How do you know that your pump is cavitating?

A.  It doesn't sound right

B.  It runs hot

C.  It won't start

D.   All of the above

The correct answer is A.  It doesn't sound right.

A pump that's cavitating sounds like it's pumps rocks or gravel.

 

Given a tank measures 50 feet long, 25 feet wide, and 15 ft deep, calculate:

  • Surface area in ft2
  • Cross-sectional area in square feet
  • Volume in cf
  • Capacity in gallons

The correct answers are:

  • Surface area in ft2

            Surface area in ft2 = Length, ft x Width, ft = 50 ft x 25 ft = 1250 ft2

  • Cross-sectional area in square feet

            Cross-sectional area is square feet = Width, ft x Depth, ft = 25 ft x 15 ft = 375 square feet

  • Volume in cf

            Volume in cf = Length, ft x Width, ft x Depth, ft = 50 ft x 25 ft x 15 ft = 18,750 cf

  • Capacity in gallons

           Capacity in gallons = Volume in cf x 7.5 gal/cf = 18,750 cf x 7.5 gal/cf = 140,625 gal

 

A chlorine atom is composed of

A.  Electrons

B.  Neutrons

C.  Protons

D.  All of the above

The correct answer is D.  All of the Above

 

Throttling the discharge valve on a centrifugal pump will the likely ______ temperature of the motor and ______ the temperature of the pump

A.  Increase, increase

B.  Increase, reduce

C.  Reduce, increase

D.  Reduce, reduce

The correct answer is C.  Reduce, increase

A, B, and D are incorrect because throttling the discharge valve on a centrifugal pump will the likely reduce temperature of the motor and increase the temperature of the pump

 

The chemical symbol for chlorine gas is

A.  Cl

B.  Cl-

C.  Cl2

D.  HOCl

The correct answer is C.  Cl2

A is incorrect because this is chemical symbol for chlorine not chlorine gas

B is incorrect because this is the chemical symbol for chloride

D is incorrect because this is the chemical formula for hypochlorite

 

Which of the following is the indicator used for pathogens?

A.  Amoebic dysentery

B.  E. coli

C.  Salmonella typhosa

D.  V. comma

The correct answer is B.  E. coli

A is incorrect because this is a pathogen, not an indicator

C is incorrect because this is a pathogen (cholera), not an indicator

D is incorrect because this is a pathogen (typhoid), not an indicator

 

Pump suction and discharge pressures are usually measured in

A.  gpm

B.  kWh  

C.  mg/L

D.  psi

The correct answer is D.  psi

A is incorrect because this is a measure of flow

B is incorrect because this is a measure of energy used

C is incorrect because this is a measure of concentration

 

Which of the following is the correct formula for chlorine in water?

A.  Cl2 + H2O → HOCl + HCl

B.  NaOCl + H2O → HOCl + NaOH

C.  Ca(OCl)2 + 2H2O → 2HOCl + Ca(OH)2

D.  HOCl → H+ + OCl-

E.  All of the above

The correct answer is E.  All of the Above

 

Wastewater and Water

How about some practice calculating detention times, surface loading rates, and weir overflow rates for the following clarifiers/sedimentation tanks?  6 tanks; each tank dimensions are:

  • Overall diameter is 130 ft

  • 12 ft SWD

  • 17 ft deep in center

  • Weir diameter is 125 ft

Click on the thumbnail below for the answers for the clarifier math chart

 

Which of the following is the correct wavelength of UV for disinfection?

A.  253.7 nm

B.  372.5 nm

C.  537.2 nm

D.  725.3 nm

    The correct answer is A

 

Which of the following describes flocculation?

A.  Suspended solids that are too small to settle

B.  Quiescent conditions that allow settleable solids to settle

C.  Neutralizing charges

D.  Growth of smaller solids into larger masses that will settle

Correct answer is D.  Growth of smaller solids into larger masses that will settle

A is incorrect because this describes colloids

B is incorrect because this describes sedimentation

C is incorrect because this describes coagulation

Hypoxic zones are caused by high levels of

A.  Colloidal suspended solids

B.  Dissolved O2

C.  Nitrogen & phosphorus

D.  Pathogens

The correct answer is C.  Nitrogen & phosphorus

A is incorrect because high levels of colloidal suspended solids cause turbidity problems

B is incorrect because hypoxic zones have low or no dissolved oxygen

D is incorrect because a breakdown in the disinfection process would lead to high levels of pathogens

Wastewater Treatment and Collection

Click on the thumbnail below for the answers for the chart of BOD and TSS math.

 

The PE for flow is ____ gpcd and PE for BOD is _____ lbs BOD/person/day.

A.  0.17 for both

B.  0.17 and 100

C.  100 and 0.17

D.  100 for both

The correct answer is C 100 and 0.17

B, C, D are incorrect because the PE (population equivalent) for flow is 100 gpcd (gallons per capita per day and 0.17 lbs BOD/person/day

Wastewater Treatment

Which of the following lab tests is used to determine the total amount of nitrogen in our effluent?

A.  TN

B.  TKN

C.  NO3

D.  NH3

    The correct answer is A

 

According to USEPA, the standard secondary removal efficiency is

A.  15%

B.  30%

C.  85%

D.  95%

The correct answer is C

A special thanks to Courtney Cswercko, Iowa DNR, for her presentation at the March 6, 2009 AceOps Annual Conference in Council Bluffs, IA!!!  Her presentation is the source of this question.

The maximum holding time for e. Coli samples according to Standard Methods is

A.  30 minutes

B.  60 minutes

C.  6 hours

D.  36 hours

The correct answer is C

A special thanks to Courtney Cswercko, Iowa DNR, for her presentation at the March 6, 2009 AceOps Annual Conference in Council Bluffs, IA!!!  Her presentation is the source of this question.

 

Which of the following is used for process control for activated sludge?

A.  MCRT

B.  Surface settling rate

C.  Volatile acids to alkalinity ratio

D.  Weir overflow rate

 

The correct answer is A

B and D are used for process control for clarifiers

C is used for process control for anaerobic digesters

 

 

 

 

The correct answer is C

 

The correct answer is D

 

The correct answer is E

It is not B because the trickling filters are not in service

 

A.  5

B.  6

C.  4

D.  1

E.  3

 

Fill-In the Missing Information
Clarifiers 6
Diameter 130 ft
SWD 12 ft
Area 13,267 ft2
Volume 1.19 MG
Weir Diameter 125 ft
Weir Length 393 ft
Avg Day Flow 51.6 MGD
Max 30-day Avg 100.6 MGD
Max Day 153.5 MGD
Peak 195.5 MGD
Avg Day HDT  3.4 hrs
Max 30-day Avg HDT  1.8 hrs
Max Day HDT  1.2 hrs
Peak HDT  0.9 hrs
Avg Day SLR 650 gpd/ft2
Max 30-day Avg SLR 1,260 gpd/ft2
Max Day SLR 2,460 gpd/ft2

 

Is this how a lagoon should look?  No, the surface should be open

What is the cause of this? Duckweed

What is the minimum recommended velocity in non-aerated grit chambers?

A.  0 fps

B.  1 fps

C.  2 fps

D.  10 fps

The correct answer is B.  1 fps

C is the minimum recommended velocity in sanitary sewers

D is the maximum recommended velocity in sanitary sewers

A settleometer is used to measure

A.  Rate of settling in a final clarifier

B.  Rate of settling in a primary clarifier

C.  Sludge depth in a final clarifier

D.  Sludge depth in a primary clarifier

The correct answer is A.  Rate of settling in a final clarifier

B is incorrect because a settleometer is used to measure the settling rate in a final clarifier

C is incorrect because a sludge judge, not a settleometer, is used to measure the sludge depth

D is incorrect because a settleometer is not used to measure the sludge depth in a primary clarifier

Collection

1.  D

2.  A

 

What is the minimum recommended velocity in sanitary sewers?

A.  0 fps

B.  1 fps

C.  2 fps

D.  10 fps

The correct answer is C.  2 fps

C is the minimum recommended velocity in non-aerated grit chambers

D is the maximum recommended velocity in sanitary sewers

 

Water Treatment and Distribution

Chloramines are used for

A.  Corrosion control

B.  Disinfection

C.  Iron and manganese removal

D.  Softening 

The correct answer is B

EPA estimates that the average household can save more than ______ gallons of wasted water per year (not to mention more than ______ % percent cost savings on their water bills) by fixing easily corrected problems such as leaking toilet flappers and dripping faucets.

A.  100 gallons; 1%

B.  500 gallons; 2%

C.  5000 gallons; 5%

D.  11,000 gallons, 10%

The correct answer is D

Special thanks to Iowa DNR's Water Supply Listserv - Feb 5, 2009 edition

 

The creamy color scale on the inside of pipes is caused by

A.  Calcium carbonate

B.  Iron oxide

C.  Manganese dioxide

D.  Magnesium carbonate

The correct answer is A

 

A is a standpipe

B is an elevated storage tank

According to the 10 State Standards, the minimum allowable pressure in the distribution system ______ PSI.

A.  20

B.  35

C.  40

D.  100

The correct answer is A

B, C, and D are incorrect because, according to the 10 State Standards, the minimum allowable pressure in the distribution system 20 PSI.

 

Water Treatment

Which of the following is used for process control for filters?

A.  Chlorine demand

B.  Detention time

C.  g

D.  Hydraulic loading rate

The correct answer is D

A is used in conjunction for disinfection

B is used for process control for sedimentation

C is used for process control with coagulation and flocculation processes

 

The main purpose of a rapid sand filter is to remove

A.  DBPs

B.  Pathogens

C.  THMs

D.   Turbidity

The correct answer is D.  Turbidity

A is incorrect because rapid sand filters are NOT used to remove DBPs

B is incorrect because disinfection is used to inactivate pathogens

C is incorrect because rapid sand filters are NOT used to remove DBPs

 

Distribution

In a distribution system, opening or closing a valve or a fire hydrant too quickly may cause

A.  Cavitation

B.  Scaling

C.  Tuberculation

D.  Water hammer

The correct answer is D.  Water hammer

A is incorrect because cavitation is a pump problem

B is incorrect because scaling is caused by hardness precipitating

C is incorrect because tuberculation is caused by corrosion

 

For questions or comments, call 515-313-1159

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