Spinning Into Control · PDF file · 2016-11-154 Historical Solids Handling Filter Waste Washwater fill-decant to load FWW basins pile-spread for solar drying to >50% solids...

Spinning Into Control:City of Sacramento’s

New 360 mgdSolids Handling Facilities

Ian PietzCity of Sacramento

Tom GilloglyCarollo Engineers

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City of Sacramento WTPs

Image Source: Google Earth Pro

Sacramento River WTP(160 MGD)

EA Fairbairn WTP

(200 MGD)

You are here

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HISTORICAL SOLIDS HANDLING

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Historical Solids HandlingFilter Waste Washwater

fill-decant to load FWW basins pile-spread for solar drying to >50% solids

Landfill Disposal

Sedimentation Basin Blowdown

fill-decant to load Sludge Lagoons

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Flow x (Turbidity + Chemicals) = Solids

Historical2005-2009 Solids Production

SR EAFFlows (mgd)

Capacity 160 200Max 122 112Ave 63 57

Raw Turbidity (NTU)Max 225 178Ave 13 3.0

555

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Historical Solids Production

SR EAFEAF[dry ton/day] SR EAF95th Percentile 80.7 2350th Percentile 6.2 1.7

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SR

Historical Landfill Disposal

[ave ton/yr] Dry Wet % SolidsSR 1,994 3,527 56%EAF 483 1,250 39%

Not enough drying area

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• <50% pay to haul water to more expensive LF

• % solids anticipated to decrease as WTPs production increases

• Losing 1 lagoon/WTP drove $1M/yr in contract dewatering

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DEWATERING SYSTEM DESIGN

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When is mechanical dewatering better than solar drying? • When there is a preference for mechanical dewatering over solar drying, and staff

are OK with associated mechanical maintenance

• When site footprint available for PROPERLY SIZED solar drying bed is not available(i.e. 6 – 10 lbs/ft2/year solids loading)

• Raw water turbidity and chemical dosing is relatively high (i.e. >100 lbs/MG solids)

• When “GUARANTEED” solids dewatering capacity, throughout the year and during all seasons, is required.

• When COST of equivalent solar drying beds is greater than mechanical dewatering equipment

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Residuals Handling Alternatives

• No change

• Contract dewatering

• All mechanical

• Hybrid (mechanical + existing infrastructure)

o Already overloaded, existing operational challenges, anticipated to get worse with time, unable to address future flows

o $52.8M20-yr present worth

o $143M20-yr present worth process peak events

o $68M20-yr present worth ~1/4th capacity of “all mechanical” through peak storage

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Hybrid Peaking at SR

0

50

100

150

200

250

Dai

ly T

otal

Res

idua

ls P

rodu

ctio

n (1

,000

lb/d

ay)

To Lagoon for Peaking No Peaking

Mechanical Dewatering

Peak Storage

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Overview of Residuals Handling Process

Sed. Basins

ThickenersHomogenizing Tanks

Centrifuges

1.5%

3-6%

3-6%

>20%

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Sed. Basins

ThickenersHomogenizing Tanks

Centrifuges

FWW Basins

Filters

1.5%

1.5-7%

1.5-7%

0.1-1.5%

>20%

SewerTruck

Drying50-60%Truck/Landfill

Recycle to head of WTP

Overview of Residuals Handling Process

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Design BasisProcess Units SR EAF

FWW Sludge CollectorsNumber No. 10 8

Total Area ft2 48,000 46,600Gravity Thickeners

Number No. 2 2Diameter ft 80 65

HomogenizersNumber No. 4 3

Total Volume gal 220,000 135,000Centrifuges

Number No. 3 2Total Capacity lbs/hr 3,600 (+1,800) 1,800 (+1,800)Total Capacity gpm 320 (+160) 160 (+160)

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NEW THICKENING & DEWATERING FACILITIES

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FWW Hoseless Sludge Collectors

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Gravity Thickeners

1117

SR WTP

EAF WTP

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Polymer System

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Homogenizers

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Five 43,200 lb/day Centrifuges

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Conveyors and Off-Haul

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Conveyors and Off-Haul

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STARTUP AND OPTIMIZATION

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Effect of Solids Loading on Cake Solids

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Solids Loading Effect on Recovery

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Effect of Feed Solids on Cake Solids

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Cake Solids Across Feed Flow Range

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Acrylamide Management

• US EPA limits acrylamide by Treatment Technique

• Polymer to Centrifuge– Control Strategy 1 – Centrate to Sewer

• No additional action– Control Strategy 2 – Centrate to Gravity Thickener

• For max dose (20 lb polymer/ton) at max SR solids processing (3,600 lb solids/hr), WTP -mgd

• 14-17 ug/L acrylamide in grab centrate samples (6 to 8 lbs/ton Clarifloc A-333P; 98% recovery)

• 0 ug/L acrylamide in control (settled water)

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Acknowledgements

– Amy Kral– Rod Frizzell– Ryan Palmer– Craig Chalmers

– Ricky Gutierrez– Patrick Carlson– Mark Gross– Yifan Zhang– Chris Cleveland

Tom Gillogly, Ph.D., P.E.

IAN [email protected]

TOM [email protected]

Questions?