Influent Screening Considerations and Case Histories - 2015 MWEA process seminar - headworks - final...

Influent Screening

Considerations and Case

Histories

Brian Hannon P.E, Moore & Bruggink

Outline

• What is preliminary treatment? • Why is preliminary treatment important? ▫ Obvious Reasons

• Types of Screening Equipment ▫ General Screen Categories ▫ Screen Media ▫ Types of Fine Screens ▫ Process Considerations ▫ O&M Considerations

• Screening Case History ▫ Second and Third Order Effects

Preliminary Treatment – What?

• Critical component of wastewater treatment

• Removal of Inorganic and Unwanted Solids

▫ Hygiene Products (including WIPES!)

▫ Pavement debris/rocks

▫ Rags

▫ Sticks

▫ Plastics

▫ Grit

▫ Some grease/fat

▫ Hair (if needed)

▫ Volkswagens?

Images: CDC.gov

www.southernwater.co.uk

Preliminary Treatment – Types

• Screening

• Comminution

• Grit Removal

• Grease Removal

• Septic Acceptance

Images: CDC.gov www.southernwater.co.uk

Preliminary Treatment – Why?

• Prevents operational problems of downstream processes

▫ Blocked Flow

Pumps

Piping/Valves

Channels

Preliminary Treatment – Why?

• Prevents operational problems of downstream processes

▫ Sensitive Processes

Membrane Bioreactors

IFAS

MBBR

Trickling Filters

Preliminary Treatment – Why?

• Prevents operational problems of downstream processes

▫ Sensitive Processes

Membrane Bioreactors

IFAS

MBBR

Trickling Filters

Preliminary Treatment – Why?

• Prevents operational problems of downstream processes

▫ Decreased capacity in unit processes

Anaerobic Digesters

Aerobic Digesters

Sludge Storage Tanks

Wetwells

Preliminary Treatment – Why?

• Decreases maintenance of downstream equipment

▫ Impeller wear

▫ Pump Ragging

▫ Pump Seals

▫ Pump Bearings

▫ Clogged Pipelines

Preliminary Treatment – Why?

• Decreases maintenance of downstream equipment

▫ Impeller wear

▫ Pump Ragging

▫ Pump Seals

▫ Pump Bearings

▫ Clogged Pipelines

Preliminary Treatment – Why?

• Decreases maintenance of downstream equipment

▫ Impeller wear

▫ Pump Ragging

▫ Pump Seals

▫ Pump Bearings

▫ Clogged Pipelines

Prevention of Ragging

• Valves Stuck in Place

• Diffusers not Working

• Undue Stress on Equipment

• Money spent to clean

Screening Equipment - General

• Categories

▫ Trash Racks/Bypass Screens = >36mm openings

▫ Coarse Screens = 6mm to 36mm openings

▫ Fine Screens = 0.5mm to 6mm openings

▫ Microscreens = < 0.5mm openings

Screening Equipment - General

• Categories

▫ Trash Racks/Bypass Screens = >36mm openings

▫ Coarse Screens = 6mm to 36mm openings

▫ Fine Screens = 0.5mm to 6mm openings

▫ Microscreens = < 0.5mm openings

Screening Equipment - General

• Categories

▫ Trash Racks/Bypass Screens = >36mm openings

▫ Coarse Screens = 6mm to 36mm openings

▫ Fine Screens = 0.5mm to 6mm openings

▫ Microscreens = < 0.5mm openings

Consider BOD and TSS removal percentages and possible energy savings!

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Screening Equipment – Screen Media

• Types of Media

▫ Perforated Plate

▫ Bars

▫ Wedge Wire

▫ “Teardrop”

▫ Mesh

▫ Other

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Fine Screening Equipment

• Types of Fine Screens

▫ Multi-rake driven screens

▫ Continuous Element

▫ Stair Screens

▫ Band Screens

▫ Drum Screens

▫ Inclined Cylindrical Screens

Screening Equipment

• Process Considerations

▫ Screen Size

▫ Screen Location

▫ Vertical Distance/Incline

▫ Headloss/Hydraulics

▫ Quantity of Screenings

▫ Washing/Compacting

▫ NPW

▫ Downstream Processes

▫ Bypassing Provisions

Screening Equipment

• Maintenance Considerations

▫ Materials of construction

Stainless

UHMWPE

▫ XP

▫ Underwater components

▫ Teeth/Bar Connection

▫ “Stapling”

▫ Bypassing Provisions

▫ Brush/Spray Bars

Case History

• Second and Third Order Effects

WHERE DO ALL THOSE RAGS GO?

Case History

• Previous screen

Case History

• Previous comminution and grit removal

Case History

• First Order Effect

▫ Influent Pumps Rag up

Case History

• Second Order Effect

▫ Ragging in aerobic digester tanks

Case History

• Third Order Effects ▫ Ragging in Sludge Thickener ▫ Ragging in Sludge Storage Tank

Case History

• Second Order Effect ▫ Rags from Primary Tanks into Anaerobic

Digester ▫ Positive Displacement Pumps ▫ Pumps rag up

• Third Order Effect ▫ Rags Build Up ▫ Outlet piping plugged ▫ Overflow piping plugged ▫ Pressure Relief Valve plugged

Case History

• Popped Cover, Overflow solids

Case History

• Popped Cover

Case History

• Rag mat buildup in digester after removing cover

Case History

• New Screens

Case History

• Lesson Learned

▫ Side Shields!

Case History

• New Raw Sewage Pumps

Case History

• New Grit Chamber

Benefits

• Decreased operations and maintenance costs

▫ Pump Ragging

▫ Plugged lines

▫ Less cleaning

▫ Less inorganics (more room for effective treatment)

▫ Better Safety for operators

Questions?

Brian Hannon, P.E. Moore & Bruggink, Inc. bhannon@mbce.com (616)363-9801