Spinning Into Control · PDF file · 2016-11-154 Historical Solids Handling Filter...
Transcript of Spinning Into Control · PDF file · 2016-11-154 Historical Solids Handling Filter...
Spinning Into Control:City of Sacramento’s
New 360 mgdSolids Handling Facilities
Ian PietzCity of Sacramento
Tom GilloglyCarollo Engineers
2
City of Sacramento WTPs
Image Source: Google Earth Pro
Sacramento River WTP(160 MGD)
EA Fairbairn WTP
(200 MGD)
You are here
3
HISTORICAL SOLIDS HANDLING
4
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
5
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
6
Historical Solids Production
SR EAFEAF[dry ton/day] SR EAF95th Percentile 80.7 2350th Percentile 6.2 1.7
7
SR
Historical Landfill Disposal
[ave ton/yr] Dry Wet % SolidsSR 1,994 3,527 56%EAF 483 1,250 39%
Not enough drying area
7
• <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
8
DEWATERING SYSTEM DESIGN
9
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
10
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
11
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
12
Overview of Residuals Handling Process
Sed. Basins
ThickenersHomogenizing Tanks
Centrifuges
1.5%
3-6%
3-6%
>20%
13
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
14
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)
15
NEW THICKENING & DEWATERING FACILITIES
16
FWW Hoseless Sludge Collectors
17
Gravity Thickeners
1117
SR WTP
EAF WTP
18
Polymer System
19
Homogenizers
20
Five 43,200 lb/day Centrifuges
21
Conveyors and Off-Haul
21
22
Conveyors and Off-Haul
23
STARTUP AND OPTIMIZATION
24
Effect of Solids Loading on Cake Solids
25
Solids Loading Effect on Recovery
26
Effect of Feed Solids on Cake Solids
27
Cake Solids Across Feed Flow Range
28
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)
29
Acknowledgements
– Amy Kral– Rod Frizzell– Ryan Palmer– Craig Chalmers
– Ricky Gutierrez– Patrick Carlson– Mark Gross– Yifan Zhang– Chris Cleveland