Simplified Wastewater Treatment Plant OperationsWorkbook

Edward Haller

• Publisher: CRC Press
• Year: 2017
• Print ISBN: 9781138474970
• eBook ISBN: 9781351416504
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

In a simple, straightforward manner, this book presents most of the major process units for wastewater treatment, addressing what the unit is and how it basically works. Along with that it provides some of the math problems associated with each unit. Each math problem, presented in English units, is usually followed by a nearly identical problem in metric units. It also presents new concepts, such as information on process microbiology, in a comfortable language so the reader can concentrate on the subject matter instead of the language used to present it. Simplified Wastewater Treatment Plant Operations provides comprehensive and technically accurate wastewater information in a clear and concise manner. The related workbook provides readers with a place to write in answers and work out problem solutions.

CHAPTER 1

Interceptors and Wet Well Pumping

QUESTIONS

1.  What is the wastewater called that comes from the household?

2.  What is the wastewater called that comes from manufacturing plants?

3.  If domestic waste and industrial waste are combined, what is the wastewater called?

4.  What kind of sewer contains only municipal waste?

5.  What kind of sewer contains only storm water?

6.  What kind of sewer contains both municipal waste and storm water?

7.  If an interceptor with both municipal waste and storm water overflows into a receiving stream, what is the event called?

8.  What problem could be caused by loose sewer line joints?

9.  If there is an increase in the amount of sand coming into the plant, what might this be an indication of?

10.  What is the ideal velocity for flow to go through an interceptor?

PROBLEMS

1.  A lift station wet well is 10 ft by 12 ft. For 5 minutes the influent valve is closed and the well level drops 2.1ft. What is the pumping rate in gallons per minute?

2.  A lift station wet well is 3.1 m by 3.6 m. For 5 min the influent valve is closed and the well level drops 0.7 m. What is the pumping rate in liters per second (L/s)?

3.  The influent valve to an 11 ft by 13 ft lift station wet well is closed for 4 min. During this time the well level dropped 1.8 ft. What is the pump discharge in gpm?

4.  The influent valve to a 3.4 m by 4 m lift station wet well is closed for 4 min. During this time the well level dropped 0.5 m. What is the pump discharge in L/s?

5.  The dimensions of the wet well for a lift station is 10 ft-9 in. by 12 ft-2 in. The influent valve to the well is closed only long enough for the level to drop 3 ft. The time to accomplish this was 6 min and 35 s. At what rate, in gallons per minute, is the pump discharging?

6.  The dimensions of the wet well for a lift station is 328 cm by 372 cm. The influent valve to the well is closed only long enough for the level to drop 50 cm. The time to accomplish this was 3 min and 37 s. At what rate, in liters per second, is the pump discharging?

7.  A lift station wet well is 11.5 ft by 13 ft. The influent flow to this well is 370 gpm. If the well level rises 1 in. in 7 min, how many gallons per minute is the pump discharging?

8.  A lift station wet well is 3.3 m by 4.1 m. The influent flow to this well is 24 L/s. If the well level rises 3 cm in 6 min, how many liters per second is the pump discharging?

9.  A lift station wet well is 130 in. by 146 in. The influent flow to this well is 450 gpm. If the well level drops 1.5 in. in 6 min, how many gallons per minute is the pump discharging?

10.  A lift station wet well is 335 cm by 370 cm. The influent flow to this well is 30 L/s. If the well level drops 2.5 cm in 7 min, how many liters per second is the pump discharging?

11.  A lift station wet well is 9.5 ft by 13 ft and has an influent rate of 750 gpm. The level in the well drops 7 in. in 14 min and two pumps in operation. If the first pump discharges at a rate of 490 gpm, at what pumping rate is the second pump discharging?

12.  A lift station wet well is 2.9 m by 4 m and has an influent rate of 47.2 L/s. The level in the well drops 12 cm in 15 min and two pumps in operation. If the first pump discharges at a rate of 30 L/s, at what pumping rate is the second pump discharging?

CHAPTER 2

Preliminary Treatment

QUESTIONS

1.  What materials are often found in the screenings?

2.  How many cubic feet of screenings will a plant remove from each million gallons of wastewater received?

3.  How many cubic meters of screenings will a plant remove from each million cubic meters of wastewater received?

4.  Name two types of coarse influent screens.

5.  What are the bar spacings for each type?

6.  Name three ways to operate a mechanical rake.

7.  Name two devices that could be used to monitor water level.

8.  What is the best velocity for the flow to go through a bar screen?

9.  Below what velocity will grit settle in the screening channel?

10.  What percentage of the screenings is typically water?

11.  Name four things that may be found in grit.

12.  Name two reasons why we would want to remove grit.

13.  Name two kinds of grit removal units.

14.  How slow should the wastewater be in order to settle the grit?

15.  If an aerated grit channel has too much air, what happens to the grit?

16.  What shape would you describe the water path in an aerated grit channel?

PROBLEMS

1.  An empty screenings hopper 4.2 ft by 5.6 ft is filled to an even depth of 26 in. over the course of 96 hr. If the average plant flowrate was 4.8 MGD during this period, how many cubic feet of screenings were removed per million gallons of wastewater received?

2.  An empty screenings hopper 1.23 m by 1.54 m is filled to an even depth of 95 centimeters over the course of 4 days. If the average plant flowrate was 29 ML/d during this period, how many cubic meters of screenings were removed per million cubic meters of wastewater received?

3.  A grit channel has a water depth of 1.1 ft and width of 1.3 ft. The flowrate through the channel is 650 gpm. What is the velocity through the channel in ft/s?

4.  A grit channel has a water depth of 9.32 m and a width of 9.41 m. The flowrate through the channel is 40 L/s. What is the velocity through the channel in m/s?

5.  A grit channel has a water depth of 14 in. and a width of 16 in. The flowrate through the channel is 0.9 MGD. What is the velocity through the channel in ft/s?

6.  A grit channel has a water depth of 31.5 cm and a width of 41.2 cm. The flowrate through the channel is 39.8 L/s. What is the velocity through the channel in m/s?

CHAPTER 3

Plant Loadings

QUESTIONS

1. What is the ceramic filter holder used in the suspended solids test called?

2. At what temperature is the filter dried?

3. What test is used to measure biological activity?

4. What is the volume of a BOD bottle?

5. What happens in a BOD test that uses oxygen?

6. How long are BOD samples incubated?

7. Generally speaking, how much DO can a BOD sample start with?

PROBLEMS

1. A suspended solids test was done on a 50 mL sample. The weight of the crucible and filter before the test was 25.6732 g. After the sample was filtered and dried, the cooled crucible weight was 25.6829 g. What was the concentration of suspended solids in mg/L?

2. A 26.1349 g crucible was used to filter 25 mL of raw influent sample for a suspended solids test. The dried crucible weighed 26.1425 g. What was the concentration of suspended solids in mg/L?

3. A BOD test was done on a 5 mL sample. The initial DO of the sample and dilution water was 7.82 mg/L. The DO of the sample after 5 days of incubation was 4.17 mg/L. What was the BOD of the sample?

4. A BOD test was done on a 5 mL sample. The initial DO of the sample and dilution water was 7.84 mg/L. The DO of the sample after 5 days of incubation was 4.08 mg/L. What was the BOD of the sample?

5. A wastewater treatment plant receives a flow of 2.74 MGD with a total phosphorus concentration of 14.3 mg/L. How many pounds per day?

6. A treatment plant with an influent flowrate of 9350 m³/d has an influent total phosphorus concentration of 14.3 mg/L. How many kg/d?

7. Raw influent BOD is 290 mg/L. If the influent flowrate is 5.70 MGD, at what rate are the pounds of BOD entering the plant?

8. Raw influent BOD is 290 mg/L. If the influent flowrate is 19,500 m³/d, at what rate are the kilograms of BOD entering the plant?

9. The plant’s influent flowrate of 4.65 MGD ...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents
• 1. INTERCEPTORS AND WET WELL PUMPING
• 2. PRELIMINARY TREATMENT
• 3. PLANT LOADINGS
• 4. PRIMARY TREATMENT
• 5. TRICKLING FILTERS
• 6. ROTATING BIOLOGICAL CONTACTORS
• 7. ACTIVATED SLUDGE
• 8. NITRIFICATION AND DENITRIFICATION
• 9. BIOLOGICAL NUTRIENT REMOVAL
• 10. WASTE TREATMENT PONDS
• 11. PHYSICAL AND CHEMICAL TREATMENT
• 12. CHLORINATION AND DECHLORINATION
• 13. SLUDGE THICKENING
• 14. ANAEROBIC SLUDGE DIGESTION
• 15. SLUDGE DEWATERING
• 16. ODOR CONTROL
• 17. LAB
• 18. ANSWERS TO THE QUESTIONS—SOLUTIONS TO THE PROBLEMS