impact of upgraded polymer activation on sludge treatment ...viscosity of 0.5% emulsion polymer...
TRANSCRIPT
Yong Kim, Ph.D.UGSI Chemical Feed, Inc.
Impact of Upgraded Polymer Activation on Sludge Treatment at Water Treatment Plant
Presentation Overview – Polymer Activation
2
Effect of Dilution Water Chemistry
Effect of Mixing Profile/Strategy
Two-stage mixing: high energy, then low energy mixing
Two-step dilution: primary mixing, then post-dilution
Case 1 - Dry Polymer Mixing System
Fairfield-Suisun Sewer District, CA
Case 2 - Emulsion Polymer System
Water Treatment Plant, PA
Effect of Dilution Water Quality
Ionic strength (Hardness): multi-valent ion hinders polymer activation
- Soft water helps polymer molecules fully-extend faster
- Hardness over 400 ppm may need softener
Oxidizer (chlorine): chlorine attacks/breaks polymer chains
- Should be less than 3 ppm
- Caution in using recycled water for polymer mixing
Temperature*: higher temperature, better polymer activation
- Water below 40 oF may need water heater
- Water over 100 oF may damage polymer chains
pH: negligible effect within pH 3 - 10
3
*David Oerke, 20% less polymer with warm water, 40% more polymer with 140F sludge, Residuals and Biosolids (2014)
Effect of Dilution Water Hardness
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1400
0 50 100 200 400
Hardness, mg/L
Soft water helps polymer chains to be fully extended
emulsion polymer, 0.5%
Kim, Y.H., Coagulants and Flocculants: Theory and Practice, 43, Tall Oak Pub. Co. (1995)
Effect of Chlorine (Oxidizing Chemical)
When effluent is used for polymer mixing, chlorine should be < 3 mg/L
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400
600
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1200
0 1 2 3 4 5 6 7 8 9 10
Vis
co
sit
y
Cl2mg/L
cP
Polymer Activation (Mixing, Dissolution)
(I) Initial Wetting (Inversion)Sticky layer formed
High-energy mixing -> No fisheyes
Most Critical Stage
(II) Dissolution
Reptation* or Uncoiling
Low-energy mixing -> No damage to polymer
Sticky Layer
WaterPolymer (gel)
* de Gennes, P.G., J. Chem. Phys., 55, 572 (1971)
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time
(I) (II)
Oil
Two-Stage Mixing (in mix chamber) higher energy mixing low energy mixing
“Discrete” Two-Stage Mixing(discrete means “separation of highand low energy mixing zones”)
One-stage vs. Two-stage Mixer – Emulsion Polymer
G-value, mean shear rate (sec-1)
1,700
4,000
1,100
1- stage mixer 2- stage mixer
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Dividing Baffle
Mixing Effect on Polymer Activation
Two-stage mixing significant increase of polymer solution efficiency
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427
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523
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500
600
Anionic Polymer Cationic Polymer
Viscosity of 0.5% Emulsion Polymer Solution, cP
1-stage mixer 2-stage mixer
37% increase
22% increase
PolyBlend® Technology
Two-Step Dilution - primary mixing (in mix chamber) at high conc. (%) and post-dilution
“Discrete” Two-Stage Mixing(discrete means “separated”)
High Concentration at Initial Wetting, Optimum 0.5% wt. (1.0 - 1.5% vol.)
Two-Step Dilution: Why Primary Mixing at High Conc? Inverting Surfactant helps to “invert (or break)” stable emulsion state
Polymer Gel: Polymer 40%
Water 30%
11
Hydrocarbon Oil: 30%
d
d = 0.1 - 2 µm
Inverting (breaker) surfactantTo enable inverting surfactant to work properly,
make polymer solution at high concentration** 1.0% - 1.25% primary mixing in mix chamber *** 0.25% - 0.5% secondary mixing (dilution)
* AWWA Standard for Polyacrylamide (ANSI-AWWA B453-06), 11, 2006** Polyacrylamide Emulsions Handbook, SNF Polydyne, 9, 2011
Stabilizing surfactant
Two-Step Dilution: How to Expedite Polymer Activation?
Primary MixingPost-Dilution
Primary mixing at “high %” Post-dilution to feed %
Polymer 1.0 gph
Polymer 1.0 gph
Water 400 gph
Water 300 gph
Water 100 gph
0.25% solution
0.25% solution1.0%
0.25%
Ideal Design
4 x higher content of inverting surfactant to expedite polymer activation
Primary Mixing
Example of Ideal Liquid Polymer SystemTwo-stage Mix Chamber + Two-step Dilution
high-shear mixing
low-shear mixingbaffle plate
Secondary dilution water
Primary dilution water
Two-stage Mix chamberTwo-stage
Mix chamber
Open-frame M-seriesCompact PB-series Open-Frame Magnum-series
Two-stage Dilution
High Energy Mixing
(3,450 rpm, < 0.5 sec)
Low Energy Mixing
(60 rpm, 20 min)
DD4 Disperser Mix and Hold Tanks
PolyBlend® Dry Polymer System
Two-Stage Mixing
Polymer Solution
Storage/Holding
(no mixing)
First-Stage of Dry Polymer Mixing:
High Energy Initial Wetting
Very High-Energy Mixing for Short Time
G = 15,000 sec-1
3,450 rpm for < 0.5 sec
Disperses Individual Polymer Particles
* No Fisheye Formation
* Shorter Mixing Time in Next Stage
Water in
Solution Out
Why Initial High-Energy Mixing is So Critical?
Polymer dissolution time, ts ~ (diameter)2 Tanaka (1979)*
d
10*d
Assume ts 1 min
ts 100 min
Initial high-energy mixing No fisheyes Significantly shorter mixing time
* Tanaka, T., Fillmore, D.J., J. Chem. Phys., 70 (3), 1214 (1979)
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Large Impeller, 70% of tank diameter
Uniform Mixing Energy
Low RPM, < 60 rpm
Low-intensity Mixing
Minimize Damage to Polymer Chain
Shorter Mixing Time with high-energy initial wetting
20 Minutes for Cationic Polymer
30 Minutes for Anionic Polymer
Minimize Damage to Polymer Chain
Second-Stage of Dry Polymer Mixing:
Low Energy Uniform Mixing
• Solano County, CA, 40 miles North San Francisco• Design capacity: 24 MGD tertiary treatment/ UV• Population served: 135,000• Polymer use for dewatering (screw press) and
thickening (GBT)
Problems with existing polymer system• Struggled to make proper polymer solution• Non-homogeneous polymer solution• Frequent maintenance issues
FKC screw press runs at average 70 gpm of sludge
(2% solids content)
Case Study: Fairfield-Suisun Sewer District, CA
Pilot Testing with Two Polymer Mix Equipment
19
Existing Polymer System• Initial wetting: air blower –> wetting head• Mixing: two (2) 4,600 gal mix/age tanks• 1 hour mixing and 2 - 4 hour aging time
UGSI PolyBlend Dry Polymer Demo System• Initial wetting: high-energy mechanical mixing • Mixing: two (2) 360 gal mix tanks • 20 minute mixing, 10+ minute transfer time
Polymer Feeder/Blower Downstairs Water Jet Wetting Head
New Polymer System (PolyBlend® DP2000) Installation
Replaced:Two 4,600 Gallon Mixing/Aging Tanks
* 6 - 12 Hour Aging Time* Corrosion Issues
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With:Two 1,000 Gallon Mixing/Feed Tanks
* 0 - 25 Minute Aging (holding) Time
New System (PolyBlend® DP2000) Performance
38.3 38.4
35.2 34.5
19.6
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1500
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2500
3000
0
5
10
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2012 2013 2014 2015 2016
FSSD saved 42% on Screw Press Polymer in 2016
despite an increase in solids throughput of 18%
Slu
dge
Pro
cess
ed, D
T/ye
ar
How to Achieve this Result?initial high-energy mixing is critical
Polymer dissolution time, ts ~ (diameter)2 Tanaka (1979)*
d
10*d
Assume ts 1 min
ts 100 min
Initial high-energy mixing (DD4) No fisheye formation Significantly shorter mixing time Less damage to polymer structure Better quality polymer solution Less Polymer Used
* Tanaka, T., Fillmore, D.J., J. Chem. Phys., 70 (3), 1214 (1979)
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Three Forms of Polymer Solutions
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Broken polymer chains by excessive mixing
Neat polymer
Fisheyes due to poorinitial wetting
Ideal polymer chains by two-stage mixing
• Located 35 miles Northeast Philadelphia• Operating capacity: 16 MGD• Population served: 40,000• Emulsion polymer use for dewatering alum-carbon
sludge with two belt filter presses (K-S)
Case Study: Water Treatment Plant, PA(Liquid/Emulsion Polymer System)
Existing Polymer SystemSiemens M1200-D10AA (2011)
New Polymer SystemUGSI MM1200-D10AA (2016)
Performance Comparison of Two Mix Chambers
PolyBlend® MM-series Mix Chamber
Residence time in low energy zone (VL ) tripled
Upgrades: Quick Disconnect Polymer Injection Check Valve
(3,450 rpm brass impeller, G value 14,000 sec-1)VHVL baffle
[VL.new= 3 x VL.old] [VH.new= VH.old ]
Polymer In
Solution Out
Water In
Quick-Disconnect PinPolymer Check Valve
• Side-by-Side Trial, Feb - May, 2016
• Polymer savings: 30% - 35%
Results of Three month Trial (1/2)
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
2/9/16 2/16/16 2/23/16 3/1/16 3/8/16 3/15/16 3/22/16 3/29/16 4/5/16 4/12/16 4/19/16 4/26/16 5/3/16 5/10/16 5/17/16
Poly
mer
Usa
ge, l
b/t
on
Test Date
Polymer Usage of Two PolyBlend Systems
M2400
MM2400
15.0
17.0
19.0
21.0
23.0
25.0
27.0
29.0
5 10 15 20 25 30 35
% C
ake
Solid
s
Polymer Usage (lb/ton)
Existing M2400-D10AA M2400-D10AA with Extended Mix Chamber
Existing M2400-D10AA M2400-D10AA with Extended Mix Chamber
Drier cake solids, 22% 23% with new polymer system
Results of Three month Trial (2/2)
Emulsion Polymer Configuration
Polymer Gel: Polymer 40%
Water 30%
Hydrocarbon Oil: 30%
d
d = 0.1 to 2 µm
Stabilizing Surfactant
Inverting (Breaker) Surfactant
Storage of Emulsion Polymer
* Drum (Tote) Mixer
* Recirculation Pump
Separated Oil
Concentrated Polymer Gels
* Drum (Tank) Dryer
Moisture Intrusion Separation (stratification)
M
Summary – Polymer Activation
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Dilution water
Hardness < 300 mg/l), Cl2 < 3 mg/l, Temperature > 60 oF
Effect of Mixing
Two-stage mixing in primary mix chamber
Two-step Dilution: Primary mixing @ > 1%, then post-dilution
(AWWA Std. B453-06)
Case 1: Fairfield-Suisun WWTP (Dry)
Case 2: PA WTP (Emulsion, new Magnum)
Thank YouAny Questions?