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Module 4: Fundamentals of Wastewater Treatment. Wastewater Treatment Plant Operator Training. Unit 1–Preliminary Treatment. Learning Objectives Explain the general purpose of preliminary treatment. Explain the purpose of screening, grit r emoval, and pre-aeration.
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Module 4: Fundamentals of Wastewater Treatment Wastewater Treatment Plant Operator Training
Unit 1–Preliminary Treatment Learning Objectives • Explain the general purpose of preliminary treatment. • Explain the purpose of screening, grit removal, and pre-aeration. • Differentiate between manually and mechanically cleaned racks and screens. • Define differences between screening and comminution. • Describe safe disposal of screenings and grit.
Manually Cleaned Bar Screen AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Mechanically Cleaned Bar Screen AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Aerated Grit Chamber AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Cyclone Separator AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Grit Washer AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Comminutor AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Comminutor with By-Pass Screen AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Barminutor AERATION TANK Diagram excerpted from Chapter 4: Racks, Screens, Comminutors and Grit Removal. In Operation of Wastewater Treatment Plants Volume I.
Unit 2–Primary Treatment: Sedimentation & Flotation Learning Objectives • Explain sedimentation and flotation principles. • List factors that indicate a clarifier is not performing properly. • Use mathematical formulas to solve for detention time, weir overflow, surface loading, and solids loading.
Detention Time Formulas Formulas Detention Time, hr. = Tank Volume, cu ft x 7.5 gal/cu ft x 24 hr/day Flow, gal/day Rectangular Tank Volume, cu ft = Length, ft x Width, ft x Height (Depth), ft Area of Circle, ft2= (0.785)(Diameter2) or ()(Radius2) Note: = 3.14 Circular Tank Volume, cu ft = Area x Height (Depth), ft Circular Tank Volume, cu ft = (0.785)(Diameter, ft)2 x Height (Depth), ft or (3.14)(Radius, ft)2 x Height (Depth), ft
Detention Time: Sample 2.1 What is the detention time when… The flow is 3.0 million gallons per day (MGD) or 3,000,000 gal/day, and Tank dimensions are 60 feet long by 30 feet wide by 10 feet deep?
Step #1 - Volume Given: Volume = 60 feet by 30 feet by 10 feet = 18,000 cu ft
Step #2 - Flow Given: Flow = 3.0 million gallons per day (MGD) or 3,000,000 gal/day
Step #3 - Calculation Detention = Tank Volume, cu ft x 7.5 gal/cu ft x 24 hr/day Time, hr Flow, gal/day = 18,000 cu ft X 7.5 gal/cu ft x 24 hr/day 3,000,000 gal/day = 3,240,000 gal/hr/day 3.0 MGD = 1.08 hours
Detention Time: Sample 2.2 What is the detention time when… The flow is 2.5 million gallons per day (MGD), and Circular clarifier is 60 ft in diameter with a depth of 12 ft?
Step #1 - Volume Reminder: Circular Tank Volume, cu ft = 0.785 x (Diameter, ft)2 x Depth, ft Volume = (0.785) x (60 ft)2 x 12 ft deep =33,912 cu ft
Step #2 - Flow Given: Flow = 2.5 million gallons per day (MGD) or 2,500,000 gal/day
Step #3 - Calculation Detention Time, hr = 33,912 cu ft x 7.48 gal/cu ft x 24 hr/day 2.5 MGD = 6,087,882 gal/hr/day 2,500,000 gal/day = 2.44 hours
Weir Overflow Rate Formulas Weir Overflow, gpd/ft = Flow Rate, GPD Length of Weir, ft Length of Circular Weir = 3.14 x Weir Diameter, ft
Weir Overflow Rate: Problem 2.1 What is the weir overflow rate when… The flow rate into the unit is 3.5 MGD, and The circular clarifier has a 75 foot diameter overflow weir
Weir Overflow Rate: Problem 2.1 Weir overflow rate, gpd/ft = 3,500,000 gallons/day 3.14 x 75 feet = 3,500,000 gal/day 235.5 feet = 14,862 gpd/ft
Surface Loading Rate: Problem 2.2 What is the surface loading rate when… • The flow into a rectangular clarifier is 5.0 MGD • The clarifier is 40 feet wide by 110 feet long by 12 feet deep • Reminder: Surface loading rate , gpd/ft2 = Flow Rate, gpd Surface area, ft2
Surface Loading Rate: Problem 2.2 Surface loading rate, gpd/ft2 = 5,000,000 gallons/day 40 ft x 110 feet = 5,000,000 gal/day 4400 ft2 = 1,136 gpd/ft2
Solids Loading Formulas • Solids Loading, lbs/day/ft2 = Solids Applied, lbs/day Surface Area, ft2 • Solids Applied, lbs/day = Flow, MGD x Conc., mg/Lx 8.34 lbs/gal
Solids Loading: Problem 2.3 Calculate the solids loading at which a clarifier is operating given the following… • The circular clarifier has a diameter of 125 feet • Forward flow is 6.0 MGD and the return sludge flow is 2.0 MGD • MLSS is 4.000 mg/L
Step # 1 - Solids Applied Reminder: Solids Applied, lbs/day = Flow, MGD x MLSS conc., mg/L x 8.34 lbs/gal Solids Applied = 8 MGD x 4,000 mg/L x 8.34 lbs/gal = 266,880 lbs/day
Step # 2 – Surface Area Given: The circular clarifier has a diameter of 125 feet Area of Circle, ft2 = (0.785)(Diameter)2 = (0.785)(125 ft)2 = (0.785)(15,625 ft2) = 12,266 ft2
Step # 3 – Solids Loading Solids Loading, lbs/day/ft2 = Solids Applied, lbs/day Surface Area, ft2 = 266,880 lbs/day 12,266 ft2 = 22 lbs/day/ft2
Unit 3–Overview of Biological Secondary Treatment Learning Objectives • List four biological secondary treatment processes. • Explain the principles of the trickling filter process. • Identify the different types of trickling filters. • Explain the principles of the rotating biological contactor (RBC) process. • Explain the principles of the activated sludge process. • List the three waste treatment pond classifications and explain the principles of each.
Trickling Filter Process AERATION TANK
Trickling Filter AERATION TANK Diagram excerpted from Chapter 6: Trickling Filters. In Operation of Wastewater Treatment Plants Volume I.
Rotating Biological Contactor Process AERATION TANK
Contact Stabilization Schematic AERATION TANK
Extended Aeration Schematic AERATION TANK
Oxidation Ditch Schematic AERATION TANK