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Arsenic Removal with
Bayoxide® E33 Ferric Oxide Media
& SORB 33® As Adsorption
Frank Stanish
Severn Trent Services, Inc.
AWWA New York Conference
Saratoga Springs, NY
April 15, 2015
Agenda
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Background on arsenic
Arsenic Toxicity
Sources of arsenic
Arsenic in Water
Arsenic Regulations
Arsenic Treatment Methods
Case Study Problem and Solution:
 Hilltown Township Arsenic Removal Project
 Frequently Asked Questions
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Arsenic Background
 Natural occurring metalloid element
 Atomic Symbol: As
 Atomic number: 33
 Atomic Weight: 74.92
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Arsenic Toxicity
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USEPA Group A Human Carcinogen
Short-term (acute) and long-term (chronic) effects
Skin, lung and bladder cancer
Acute GI damage
Cardiac problems
Vomiting / Diarrhea
Dehydration
Partial paralysis / blindness
Hemolysis
Vertigo
Shock / Death
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Arsenic Chemistry
Arsenic found in ground waters is normally in an inorganic form as a
soluble oxyanion species. It has 2 valence states, As(III) and As(V).
“Oxidized” As(V) Oxyanion Dissociation
H3AsO4  H2AsO4- + H+ pKs = 2.2
H2AsO4-  HAsO42- + H+ pKs = 6.9
HAsO42-  AsO43- + H+ pKs = 11.5
“Reduced” As(III) Oxyanion Dissociation
H3AsO3  H2AsO3- + H+ pH 6 - 8
In waters within a natural pH range, the following species are present:
H3AsO3, H2AsO3-, H2AsO4- & HAsO42As(III) occurs mainly under reducing conditions, e.g., in the absence of oxygen.
When this water comes in contact with air, As(III) is oxidized to As(V).
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Arsenic Sources in US Drinking Water
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USEPA Arsenic Rule & Severn Trent’s Role
Timeline - Lower Potable Water Arsenic Levels
Current Limit in 1990’s - 50 g/L
1993
WHO Recommends 10 g/L
1994
USEPA Recommends 2-20 g/L
2000
New EC Directive
2003
UK Adopts 10 g/L Standard
2006
USEPA Compliance for 10 g/L MCL
Severn Trent Water
Severn Trent Services’ Sister Company in the UK
16 Well Water Sites with As > 10 g/L
Total Treatment Capacity - 46.8 MGD (177 ML/Day) since 2003
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As Removal – Treatment Selection
 Adsorption
 Simple & non-regenerative in most cases
 Single step process for most applications
 Coagulation/Filtration
 Cost effective for large scale systems (over 4 MGD)
 Effective for high Fe/Mn waters
 No chemicals besides disinfection if Fe/As wgt ratio > 25
 Reverse Osmosis
 Effective if other TDS must be removed
 Won’t remove As(III)
 Ion Exchange
 Good for waters with high As & pH and low SO4 & HCO3
 Hybrid resins with impregnated Fe Oxide – Selective for As
 Requires regeneration/postreatment; won’t remove As(III)
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SORB 33® Adsorption with Bayoxide® E33 Media
 SORB 33® - Severn Trent’s Adsorption Process
 STS & Lanxess Partnered to Develop Granular Ferric Oxide
(GFO) Media for As Removal
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Lanxess: Large Technical Oxide Producer
Specialists in Iron Oxide Technologies
Bayoxide® E33 (GFO) - Adsorption Media
Exclusive Agreement between STS & Lanxess
NSF Standard 61 Approved
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Adsorption - SORB 33® Systems
Water Flows through a bed of media
 Pros
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Easy Operation
Little automation
Simple Maintenance
Not complex
Lowest Capital
Commonly lowest O&M
 Cons
 Complex Waters with multi
contaminants
 Causes low bed volumes
Most accepted technology
 Majority of projects in US have
selected adsorption
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Adsorption - SORB 33® Systems
Bernallilo, NM
Four 4’-Ø Adsorbers
450 gpm
Loma Linda, CA
Four 14’-Ø Adsorbers
3,000 gpm
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Adsorptive Media Pilot Testing – 3rd Party
 Breakthrough Curves – determine best performance
 4 different medias tested at Mesa, AZ by DSWA
B ed V o lu m e v s. A rsen ic
35
30
Arsenic, ppb
25
A v erage In flu en t
W R T Z33
G FH
S o lm etex A sX n p
B ayo x id e E 3 3
20
15
10
5
0
0
1 0 ,0 0 0
2 0 ,0 0 0
3 0 ,0 0 0
4 0 ,0 0 0
5 0 ,0 0 0
6 0 ,0 0 0
B ed V o lu m es
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Test Evaluation – Breakthrough Curves
Breakthrough Curve Measures Media Performance - Longevity
 Arsenic effluent levels vs volume treated (“BV’s” or gallons H2O/cu ft of media)
 As Breakthrough – Point at which media needs replacement
 The higher the BV’s to breakthrough, the lower the operating cost
Typical SORB 33® Arsenic Adsorption Curve
40
Concentration (μg/L)
Influent As
30
20
As MCL
10
Treated
Water As
As Breakthrough
0
0
25,000
Time (based on 75% Use Factor):
50,000
6 Mos
75,000
100,000
125,000
12 Mos
Bed Volumes of Water Treated (BV’s)
150,000
18 Mos
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On-site Pilot Test Program
Program Scope
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4”- Clear Column with
Media
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Manual Valves
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Simple Instruments
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Consistent Water Supply
Vent
V-11
E33 Feed
Sample
P-04
B’wash Discharge
P-01
S-08
Test Protocol
P-01
S-06
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PG
Backwash
Sample
P-03
P-04
B’wash Supply
P-02
FI/FQI
P-02
FQI
P-03
FI
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Weekly Sampling
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2-6 Month Program
E33
GFO
Media
Well
Water
Media
Drain
P-09
Effluent/Media Backwash
Data Collection & Monitor
Pres Reg’r
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Rate Set
PDI
Media
Support
S-07
Treated
Water
Or
Backwash
Effluent
Rate Set
Treated Water
Sample
/Drain
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Coagulation / Filtration - Omni-SORB™ Media
 Product Composition
 5% Manganese Dioxide (MnO2)
impregnated quartz (sand)
 Non-porous blackish gray
“catalytic” filtration media
 Dense media – 88 lb/ft3
 Screen Size – 18 x 60 mesh
 Dustless – facilitates backwash
 Producer
 Fermavi (Brazil) – Mines rich MnO2 ore, refines into product
 Media Life – 9+ Years; Disposable as nonhazardous
waste
 Service Conditions
 Filtration rates of 7-10 gpm/ft2
 Backwash rates of 14-16 gpm/ft2
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Coagulation / Filtration - Omni-SORB™ Media
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Coagulation / Filtration
Iron Removal
 Removes Fe and Mn
 Removal As/Fe/Mn
 Needs high Iron level
 Fe:As - 25:1 or better
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As/Fe/Mn or Fe/Mn
 Catalyze the Fe and Mn in
an oxidation/precipitation
process
 Coagulation / Filtration of Fe
oxide & Mn oxide
 Ferric chloride addition if
needed
 As adsorbed by Fe oxide
 Backwash
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Omni-SORB Systems
 Parallel Flow Filters
 Automated Valves
 Process Controls & PLC
Rozel, KS – 600 gpm
Fe & Mn Removal
Three 6’-Ø Filters
Houghton, NY – 700 gpm
As Coag Filtration
Four 7’-Ø Filters
N+1 Redundancy
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Application Inquiry to
Full Scale System …
Step 1
Site Qualification Form
 Complete & Submit
 Client & Contact Info
 Flows, contaminants &
concentrations
Severn Trent Analysis
 Conceptualize
 Design
 Flexibility
 Budget Proposal
 Budget Capital
 Budget O&M
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Water Quality
 Characterization Key to Design
 Site Qualify Form’s analytical table highlights key species
 Key Species
 Arsenic (As, g/L) – Bypass if As <25; Series if As >25
 pH (no units) – Use CO2 or Acid to adjust if water pH >8.0 and/or high
SiO2
 Phosphate (PO4 or P mg/L) – Consumes media capacity; Use OmniSORB if PO4 > 0.8 (0.3 mg/L as P)
 Silica (SiO2, mg/L) – Coats media above 40; use pH adjust
 Iron (Fe, mg/L) – If Fe >0.2, As is reduced; chlorination required; If Fe
>0.35, consider Omni-SORB
 Manganese (Mn, mg/L) – If Mn >0.06, Mn buildup in bed, makes
backwash difficult; chlorination required; Omni-SORB pretreat
 Vanadium (V, g/L) – Consumes media capacity; pH adjust helps
reduce its effect
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Sizing & Estimate
Summary …
Adsorption Example
Process Sizes System
 Vessel Size
 Media Volume
 Performance – BV’s, etc.
 Flows Configuration
 Operating Costs: Includes
annualized media replace
& chemicals
Proposals Estimates Cost
 ROM or Budget
Rough Order of Magnitude
 Issue to Client
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Media Replacement & Disposal
Media Removal
 STS subcontractors
 Vacuum removal or
vactor truck
 Fill rolloffs or sacks
 TCLP analysis – verify
media is non-hazardous
Media Replacement
 Gravity fill - 52 ft3 sacks
Roof Hatch Added
 Hydraulic fill eductors
Aqua Pennsylvania Site
Roof Hatch Added for Gravity Fill
30 Minute Fill - 52 ft³ per Vessel
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Case Study – Hilltown Township, PA
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Hilltown Township Well No. 2
Hybrid Fe/Mn Filtration & As Adsorption
 Well No. 3 – 300 gpm
 Multiple Contaminants
 Arsenic – 15 µg/L
 Iron – 250 µg/L
 Manganese – 110 µg/L
 Aside from As removal, needed to remove Fe & Mn
 Black & red water issue
 Hybrid design – 1 OmniSORB filter & 2 E33 Adsorbers
 Oxidize & filter all of the water to remove Fe & Mn
 Treat 50% of filtered water through adsorption
 Bypass and blend remainder
 System in service for 9 years
 Bayoxide E33 lasted 7 years before replacement
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Hilltown Township
Hybrid Fe/Mn Filtration & As Adsorption
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Questions?
Acknowledgements:
Gary Weaver - Principal
Castle Valley Consultants, Inc.
10 Beulah Road
215 348 8257
[email protected]
Severn Trent Water Purification, Inc.
Gary M. Lohse, P.E. – Regional Sales Manager
3000 Advance Lane
Colmar, PA 18915
T: +1 215 859-3814
E: [email protected]
www.severntrentservices.com