Yong Kim, Ph.D. UGSI Solutions, Inc. Vineland, NJ Impact of Efficient Polymer Activation on Improving Sludge Thickening and Dewatering MWEA 94 th Annual Conference Boyne Falls, MI, June 23-26, 2019
Yong Kim, Ph.D.UGSI Solutions, Inc.
Vineland, NJ
Impact of Efficient Polymer Activation onImproving Sludge Thickening and Dewatering
MWEA 94th Annual ConferenceBoyne Falls, MI, June 23-26, 2019
Presentation Overview
1. Basics of Polymer• Why polymer activation matters• Viscosity - indicator of polymer solution quality• Effect of dilution water
2. Science of Polymer Activation• Two-stage mixing - dry and emulsion polymers• Residence time - sufficient for polymer uncoiling/dissolution• Two-step dilution - emulsion polymers• Weissenberg effect
3. Case Studies• Neshaminy Water Treatment Plant, PA – emulsion polymer• F. Wayne Hill WRC, Gwinnett County, GA – emulsion polymer• Fairfield-Suisun Sewer District – dry polymer
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Annual Average Dewatering Cost (2011-2014) = $3.7M
K. Tagney and R. Gupta, Reducing Dewatering Costs through Optimization Program, 2017 WEFTEC.
Dewatering Cost at EMWD: $3.7M / yearPolymer Cost: Average $1.2 M / year
Viscosity – Indicator of Polymer Solution Efficiency
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Intrinsic Viscosity of Polymer Solution
Sakaguchi, K.; Nagase, K., Bull. Chem. Soc. Japan, 39, p.88 (1966)
Quantity of friction as measured by the force resisting a flow inwhich parallel layers have at unit speed relative to one another
Polymer supplier data sheet provides a starting pointfor viscosity – critical factor for polymer efficiency
Solenis, Inc.
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 reclaimed water for polymer mixing
* Serious negative impact on aging/maturingTemperature*: higher temperature, better polymer activation
- Water below 40 oF may need water heater- Water over 100 oF may damage polymer chains
Suspended Solids/ Turbidity:- In-line strainer recommended- Caution in using reclaimed water for polymer mixing
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*David Oerke, 20% less polymer with warm water, 40% more polymer with 140F sludge, Residuals and Biosolids (2014)
Polymer Activation (Mixing, Dissolution)
(I) Initial Wetting (Inversion)Sticky layer formedHigh-energy mixing -> No fisheyesMost Critical Stage (brief)
(II) DissolutionReptation* or UncoilingLow-energy mixing -> No damage to polymer
Requires longer residence time
Sticky Layer
WaterPolymer (gel)
* de Gennes, P.G., J. Chem. Phys., 55, 572 (1971)
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time
(I) (II)
Oil
(1) 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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DividingBaffle
One-Stage Mixing vs. Two-Stage Mixing
Two-stage mixing significant increase of polymer solution efficiency
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427
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523
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600
Anionic Polymer Cationic Polymer
Viscosity of Emulsion Polymer Solution, cP
1-stage mixer 2-stage mixer
37% increase
22% increase
(2) Two-Step Dilution - primary mixing (mix chamber)at high conc. (%) then post-dilution to feed
High Concentration at Initial Wetting,Optimum 0.5% wt. = 1.0 ~ 1.5% vol.Need to post-dilute to 0.5% or lower
Inversion of Emulsion: water-in-oil oil-in-water
99.5% Water
70% Polymer gel
30% Oil
Oil
Polymer gel
Polymer 1 gal
Water 100 gal
Neat Polymer > 1.0 % Polymer Solution
Inverting Surfactant
Especially Important for Clarifier at WTP Strip “oil” off the polymer surface- help polymer get exposed to water quickly- break and disperse oil in micron-sized entities
Inverting Surfactant
* AWWA Standard for Polyacrylamide (ANSI-AWWA B453-06), 11, 2006
Two-Step Dilution: Expediting Polymer Activation
Primary MixingPost-Dilution
Primary mixing at “high %” Post-dilution to feed %
Polymer1.0 gph
Polymer1.0 gph
Water400 gph
Water300 gph
Water100 gph
0.25%solution
0.25%solution1.0%
0.25%
Ideal Design
4 x higher content of inverting surfactantto expedite polymer activation
Primary Mixing
Vt = Residence time (t) in flocculating basin: Gt-value
Gt-value = mean shear rate x residence time
Contact time (T) in clear well design: CT calcCT calc = residual chlorine concentration x contact time
Residence time (t) in polymer activationSecond stage of polymer activation – “uncoiling” of long chain polymer moleculesrequires more time under low energy mixing than high energy first stage mixing
(3) Residence Time (in mix chamber)Sufficient residence time of low-energy mixing zone is
required for complete polymer dissolution
Residence Time of Low Energy Mixing Zone
Low energy mixing stage requires“longer” residence time than initialhigh energy mixing stage
Effect of Residence Time in Mix Chamber
Volume of low-energy zone: VLVL,MM = 3* VL,M
M,
0.5
gal
MM
,1.
0 ga
l
370
1795
397
1936
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1500
2000
2500
Cationic Anionic
Effect of Residence Time in Mix Chamber(0.5% polymer solution viscosity, cP)
M MM
• Located Northeast Philadelphia• Operating capacity: 16 MGD• Population served: 40,000• Emulsion polymer use for dewatering alum-carbon
sludge with two 2-M belt filter presses (K-S)
Case Study: Emulsion Polymer SystemNeshaminy Water Treatment Plant, PA
Existing Polymer SystemSiemens M1200-D10AA (2011)
New Polymer SystemUGSI MM1200-D10AA (2016)
Performance Comparison of Two Mix ChambersPraestol A3040L, HMW Anionic Emulsion Polymer
• Side-by-Side Trial from Feb to May 2016• Polymer savings ~ 30%• Sludge throughput increased by 10%• Cake solids improved marginally from 22% to 23%
Impact of Residence Time of Low-Energy Mix ZoneNeshaminy Water Treatment Plant, PA
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/to
n
Test Date
Polymer Usage of Two PolyBlend Systems
M1200
MM1200
MM
, 1.
0 ga
lM
, 0.
5 ga
l
• Design capacity: 60 MGD• Annual cost of polymer is significant ($1.2 million)
• Thickening ~ $400,000 (RDT)• Dewatering ~ $800,000 (Centrifuge)
• SNF/Polydyne Clarifloc SE-873, crosslinked
Case Study: Emulsion Polymer SystemF. Wayne Hill WRC, Gwinnett County, GA
Courtesy by Jacobs Engineering and Gwinnett County
Three Polymer Systems for Pilot TrialsOptimum feed concentration: 0.5% to 0.7%
UGSI MM2400-P30AB(2400 gph/30 gph)Two-stage mixing
Mechanical, 3450 rpm
FloQuip EA70P(4200 gph/30 gph)Single-stage mixing
Hydraulic
ProMix L6000-30P(6000gph /30 gph)Three-stage mixing
Mechanical, 1725 rpm
Courtesy by Jacobs Engineering and Gwinnett County
Trial results demonstrate that UGSI two-stage mixingprovides significant polymer savings vs. FloQuip
(25% with UGSI, 10% with ProMinent)
Test Polymer BlendingUnit & Centrifuge
AveragePolymer
Dose(lbact/dT)
CentrifugeSludge FeedFlow Range
(gpm)
Average DryCake Solids,
TS (%)
AverageCentrate TSS
(mg/L)
Average PercentCapture
(%)
Pilot 1
UGSI Polyblend®Centrifuge #10 25.7 (± 4.2) 100 - 180 20.4 (± 1.7) 184.4 (± 48.4) 99.5 (± 0.1)
SNF FloQuipCentrifuge #5 33.9 (± 4.1) 100 - 200 21.5 (± 0.8) 193.5 (± 34.5) 99.5 (± 0.1)
Pilot 2
ProMinent ProMix®Centrifuge #10 28.0 (± 3.2) 100 - 180 20.1 (± 1.8) 190.6 (± 41.4) 99.5 (± 0.1)
SNF FloQuipCentrifuge #5 31.3 (± 1.8) 100 - 200 21.7 (± 1.5) 183.0 (± 20.2) 99.5 (± 0.1)
Courtesy by Jacobs Engineering and Gwinnett County
First StageHigh Energy Mixing
(3,450 rpm, < 0.5 sec)
Second StageLow Energy Mixing
(60 rpm, 20 min)
DD4 Disperser Mix and Hold Tanks
PolyBlend® Dry Polymer SystemTwo-Stage Mixing
Polymer SolutionStorage/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 inSolution Out
Mixing Tank for Dissolution of Dry Polymer
Patented Hollow-Wing Impeller
No Weissenberg Effect
Large Impeller, 70% of tank diameter
Uniform Mixing Energy
Low RPM, 60 rpm
Low-intensity Mixing
Minimize Damage to Polymer Chain
Shorter Mixing Time – Due to high energy DD4
20 - 30 min for Cationic Polymer
30 - 40 min for Anionic Polymer
Short mixing time minimizes damage
to polymer chain
Weissenberg Effect (undesired) in Polymer Mixing
Water(Newtonian)
Polymer Solution(Non-Newtonian, Pseudoplastic)
extremely low mixing
very high mixing
extremely low mixing
* Polymer solution exceeding “critical concentration” climbs up mixing shaft* Extremely non-uniform mixing* Critical factor for “conventional” polymer mix tankmax 0.2% limit for HMW polymer
Notice polymer solution is “climbing” up the mixer shaft(30 min after mixing (Nalco TX13182): 0.25%, 0.50%)
Polymer Mixing Tank With No Weissenberg Effect
Impeller / tank diameter > 0.7 Cationic Polymer Solution @ 0.75%
Eye of impeller
Hollow-wing impeller
PVC sleeve aroundmixer shaftseparates polymersolution fromrotating shaft
PVC sleeve preventsWeissenburg effect at highconcentration, up to 1.0%
Why high conc. solution?* Smaller tank size* Longer shelf life solution
Rotating shaft
• 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• Polymer performance inconsistent• Frequent maintenance issues
FKC screw press runs at average 70 gpm of sludge(2% solids content)
Case Study: Dry Polymer Mixing SystemFairfield-Suisun Sewer District, CA
Pilot Testing with Two Polymer Mix Equipment
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Existing Polymer System• Initial wetting: air blower –> wetting head• Mixing: two (2) 4,600 gal mix/age tanks• 1 hour mixing and 4 - 8 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
Newly Installed FSSD Polymer System
Hollow wing impellerExisting impeller
Old: Two 4,600 gal mixing/aging tanks* 60 min mixing, 2-4 hour aging
New: Two 1,000 gal mixing tanks* 30 min mixing, 15 min holding
FSSD Installed New PolyBlend®DP2000Performance Data in 2016
38.3 38.435.2 34.5
19.6
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2012 2013 2014 2015 2016
FSSD saved 42% on Screw Press Polymer in 2016despite an increase in solids throughput by 18%
Slud
ge P
roce
ssed
, DT/
year
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 formationSignificantly shorter mixing time Less damage to polymer structureBetter quality polymer solution Less Polymer Used
* Tanaka, T., Fillmore, D.J., J. Chem. Phys., 70 (3), 1214 (1979)
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• Good quality dilution water will yield to more efficient polymer solution.• Emulsion polymer activation
• Two-stage mixing: very high-energy mixing at initial wetting stage iscritical to prevent fisheye formation, followed by low-energy mixing tominimize damaging polymer chain.
• Sufficient residence time of low-energy mixing stage is required toachieve fully dissolved homogeneous solution.
• Two-step dilution helps proper polymer activation by maximizing thevalue of breaker surfactant.
• Dry polymer activation• Very-high energy mixing at initial wetting stage is critical.• Low-speed and uniform mixing impeller that prevents Weissenberg
effect should be used at the second stage mixing tank.
Summary
Thank YouAny [email protected]