CEEN 572 Introduction Environmental Engineering Pilot Plant Laboratory th (

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CEEN 572
Environmental Engineering Pilot Plant Laboratory
Introduction
Instructor: Prof. Tzahi Cath ([email protected])
TA: Hooman Vatan ([email protected])
Course objectives
Apply knowledge and understanding of water
treatment processes to a real-world problem
 Enhance students ability to apply math, science, and
engineering concepts and skills to the analysis, design,
and optimization of drinking water treatment systems
 Teach students to effectively communicate the results
of their technical work through professional quality
written reports and oral presentations
 Enhance teamwork skills through team project
assignments

Course organization
Meeting times: Wednesdays 4:30-7:00 pm and
Fridays 1-3 pm in the IETL (CO 166 or Golden Water
Treatment Plant)
 Course webpage:
http://inside.mines.edu/~tcath/courses/CEEN572_pilot/
 Office hours: CH 128, by appointment
 Textbook: No specific textbook recommended. Course
webpage is one of the resources

References for CEEN 572
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HDR Engineering Inc. (2001). Handbook of Public Water Systems. 2nd Edition. John
Wiley & Sons, Inc.
American Water Works Association (1999). Water Quality and Treatment. Fifth
Edition. McGraw-Hill.
American Water Works Association (1998). Water Treatment Plant Design. Third
Edition. McGraw-Hill.
Faust. S. and Aly, O. (1999). Chemistry of Water Treatment. 2nd Edition. Lewis
Publishers.
Qasim, S. R., Motley, E. M., Zhu, G. (2000). Water Works Engineering. Planning,
Design & Operation. Published by Prentice Hall PTR
MWH (2005). Water Treatment: Principles and Design. 2nd Edition. John Wiley &
Sons, Inc.
Howe, K. and Clark, M. (2002). Coagulation Pretreatment for Membrane Filtration.
AwwaRF Report
AWWA (2005). Microfiltration and Ultrafiltration Membranes for Drinking Water.
Manual of Water Supply Practices M 53.
Grading CEEN 572
Laboratory reports and presentations
 Participation and peer evaluation
 Project Presentation
 Final Report (WRITING…)

25%
30%
15%
30%
What do you need to know?
Fluid Mechanics: Bulk fluid properties, mass
conservation equations, laminar/turbulent flow
regimes, reactor flow models
 General knowledge in conventional water treatment
(also prerequisites): CEEN 470 (ESGN 453); CEEN 471
(ESGN 453); CEEN 570 (ESGN 504); CEEN 571 (ESGN
506)
 or consent of the instructor

Golden Water Treatment Plant
Conventional Water Treatment
Golden Water Treatment Plant
SPLIT TRAIN (RAPID MIX,
FLOCCULATION, SEDIMENTATION)
RAW WATER
FROM CLEAR
CREEK
KMnO4
FLOC AID
(PRE-OXIDATION)
FERRIC
SULFATE
PRESEDIMENTATIO
N & STORAGE
PONDS
RAW WATER
PUMP STATION
NaOH
Cl2
SODA RAPID
FLOCCULATION
MIX
ASH
SETTLER
MULTIMEDIA
FILTRATION
Cl2
DISTRIBUTION
SYSTEM
CLEARWELL
HIGH SERVICE
PUMPS
Golden Water Treatment Plant
Golden Water Treatment Plant

The Golden water treatment plant has just upgraded
the multimedia filters and sedimentation basins:

New underdrain (leopold® vs. gravel/rocks)
http://www.xylemwatersolutions.com/scs/usa/Documents/LB0031326_Leopold_TypeS_Underdrain_Brochure_sm.pdf

Dual media vs. mixed media

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New sand
Conventional filtration vs. greensand filtration
To satisfy Level 3 Partnership for Safe Water, the
settled turbidity should be <1 NTU and filtered
turbidity < 0.1 NTU
Understanding the Problem
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The Golden Water Treatment Plant (GWTP) currently uses
conventional treatment (oxidation, coagulation, flocculation,
sedimentation, multi-media filtration, and disinfection) to
provide the city of Golden, Colorado with safe, high-quality
drinking water.
The GWTP voluntarily participates in the Partnership for Safe
Water, which requires exceeding regulations and optimizing
operations.
Treatment challenges faced by Golden include consistently
high levels of manganese and seasonal variations in raw water
quality that result in elevated concentrations of total organic
carbon (TOC), turbidity, and manganese.
Understanding the Problem


The filter media was recently replaced and the GWTP might
be considering in the future retrofitting the plant with
ultrafiltration (UF) membranes.
In the springs of 2009 and 2010 in-depth investigations into
the feasibility of implementing UF were carried out. These
examinations included a review of current literature, site
visits to plants employing the technology, bench-scale testing
with raw water, pilot-scale operation of a polymeric UF
module at the GWTP, and a redesign and cost estimate.
Understanding the Problem


The feasibility of UF installation was evaluated on the basis of
a potential reduction in chemical use, constituent removal,
system operations, reliability, and cost, and how all of these
elements may contribute to long-term sustainability.
However, new generation of UF and MF membranes, and
specifically ceramic MF or UF membranes, are emerging that
can change the decision of the City of Golden and make them
be more willing to adopt ceramic membrane technology.
Research Questions


Therefore, the City is asking us to test novel ceramic membrane
technology, compare it to polymeric membrane technology, and
to the current operation through experimental and technoeconomic analysis.
Aqua-Aerobic Systems Inc. is graciously lending us a pilot UF
system. The research tasks being posed to this year’s class are:

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Evaluate the application of a ceramic UF/MF system at the GWTP
Optimize operating condition and pretreatment for the ceramic MF/UF
system
Evaluate and compare the techno-economic performance of the ceramic
membrane system and compare to conventional treatment and to
polymeric membrane.
Develop recommendation to the City of Golden based on experimental
results and feasibility assessments.
Golden’s Desired Solution
Recarbonation/pH control of water with CO2
 Develop and conduct bench scale study
 Develop and conduct pilot scale study
 Test impacts of different operating conditions

What research/teaching
infrastructure is
available to us?
CSM-Golden Pilot Plant
Mini-Pilot Treatment System
pH
pH adjustment
Backwash
Waste
Chlorine
V-2
V-2
V-13
V-3
V-14
Flocculation Basin
Overflow
Coag.
V-1
KMnO4
Feed
Tank
turbidimeter
V-11
V-4 V-12
V-5
V-10
Backwash
Lines
V-6
V-7
V-8
V-9
Mini-Pilot
Flow Diagram
Bench Scale Systems

Jar tester…
Pilot Scale Ceramic MF/UF System
Team Assignments

Compile information on relevant federal and state regulations
for TOC/NOM, DBPs, T&O, turbidity, manganese removal, and
filtration conditions related to surface water treatment plants.
Prepare presentation for January 20

Compile data from Golden water treatment plant and prepare a
presentation and discussion for our meeting on January 22

Conduct review on membrane treatment processes for TOC and
T&O removal form surface water,

Develop draft experimental plan for pilot scale study using the
Aqua’s pilot system
Lab Safety for CEEN 572:
General Laboratory Rules
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Use safety glasses at all times in the laboratory
 You must use safety glasses during transport of chemicals between labs
Use laboratory coats when working in the laboratory
 Don’t use them outside of a laboratory (except when moving between
labs)
Use gloves when handling chemicals (see label and MSDS)
 Remove gloves when leaving the laboratory
Biological and chemical materials must be transported between
laboratories:
 with secondary containment (e.g., bucket or cart with raised sides)
 with lab coat and gloves
 with safety glasses worn
Lab Safety for CEEN 572:
General Laboratory Rules
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Closed-toed shoes must be worn at all times
Hands must be washed with soap before leaving the laboratory
No food, beverages, or cosmetics are allowed at any place within the
laboratory
Hair that is long enough to reach the shoulders must be tied back
All containers of samples or chemicals must be labeled
All benches and hoods must be kept free of clutter, dust, and residue
from any spills
All benches must be wiped clean after use
All sinks must be kept free of glassware and instrumentation
All instrumentation, particularly balances, must be thoroughly cleaned
after use
Lab Safety for CEEN 572 (cont.)
Waste Disposal
 All chemical waste must be disposed of in designated waste containers
 All containers must be labeled with contents and date
 Contact wastes: collect in designated yellow buckets
Individual Responsibilities
 Notify the supervising faculty of any medical conditions that could be
affected by carrying out laboratory activities
 Notify the supervising faculty of any safety concerns
 Observe the above laboratory rules
 Assist other laboratory users in observing general rules
 Immediately clean routine spills
 Immediately report non-routine spills to the supervising faculty and to EHS
 Memorize locations and uses of all exits, eye-wash stations, showers, fire
alarms, and emergency phones
Lab Safety for CEEN 572:
Golden Water Treatment Plant
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Over the years we have established VERY GOOD relationships with the
city of Golden (!!!)
You will get access to the water treatment plant.
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THIS IS NOT OBVIOUS AND REQUIRE CAREFUL AND OUTMOST PROPER BEHAVIOR
Announce visiting plans
Report in and out
Don’t take things without permission
Return things to their place
Use of lab
Hygiene
Semester Schedule
http://inside.mines.edu/~tcath/courses/CEEN572_pilot/
Overview of Conventional
Water Treatment
Coagulation/Flocculation
Rapid mix
Flocculator
Turbidity and NOM in Water:
Surface Phenomena

Electrostatic force

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principal force contributing to stability of suspension
electrically charged particles
Van der Waals force


attraction between any two masses
opposing force to electrostatic forces
Double Layer Model of Colloidal Particles
Satisfy
Electroneutrality
Forces Acting on Colloids
Destabilization Mechanisms

Compression of the double layer (DLVO Theory)

increasing the ionic strength
Compression of Double Layer
Destabilization Mechanisms

Compression of the double layer (DLVO Theory)

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increasing the ionic strength
Adsorption and charge neutralization

adding a coagulant (metal salt)
Charge Neutralization
Destabilization mechanisms

Compression of the double layer (DLVO Theory)

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Adsorption and charge neutralization

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increasing the ionic strength
adding a coagulant (metal salt)
Enmeshment in a precipitate (“sweep-floc coagulation”)
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high coagulant dose (metal salt)
coagulant forms insoluble precipitates
dominant mechanism applied (pH 6-8)
Sweep-Floc Coagulation
Al2(SO4) 3
+
Sweep-Floc Coagulation
Al2(SO4) 3
Al2(SO4) 3
+
+
colloids are
enmeshed
Restabilization
Destabilization Mechanisms

Compression of the double layer (DLVO Theory)

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Adsorption and charge neutralization


adding a coagulant (metal salt)
Enmeshment in a precipitate (“sweep-floc
coagulation”)
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increasing the ionic strength
high coagulant dose (metal salt)
coagulant forms insoluble precipitates
dominant mechanism applied (pH 6-8)
Interparticle bridging

synthetic organic polymer
Destabilization of colloidal
particles
Metals salts used for destabilization:
 aluminum sulfate (alum)
 aluminum chloride
 ferric sulfate
Solubility of metals salts:
 ferric chloride
Operating range
 ferrous sulfate
Factors Affecting Coagulation
Alkalinity/pH
 NOM
 Turbidity
 Temperature

pH and Coagulation

The pH at which coagulation occurs is the most
important parameter for proper coagulation
performance, as it affects:
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Surface charge of colloids
Charge of NOM functional groups
Charge of the dissolved-phase coagulant species


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e.g., Alum  Al3+, Al(OH)2+, and Al(OH)4-
Surface charge of floc particles
Coagulant solubility
Stoichiometry of Metal Ion Coagulants
Overall stoichiometric reaction
Al3+ + 3H2O <-> Al(OH)3(am) + 3H+
Fe3+ + 3H2O <-> Fe(OH)3(am) + 3H+
H+ will react with alkalinity
FeCl36H2O + 3HCO3- <-> Fe(OH)3(am) + 3Cl- + 3CO2 + 6H2O
Fe2(SO4)39H2O + 6HCO3- <-> 2Fe(OH)3(am) + 3SO42- + 6CO2 +
9H2O
Al2(SO4)314 H2O + 6HCO3- <-> 2Al(OH)3)(am) + 3SO42- + 6CO2 + 14H2O
Coagulation Using Different Coagulants
Design of coagulation processes

The design of coagulation process involves:

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Selection of proper coagulant chemicals and their dosing
Design of rapid mixing and flocculation basins
Coagulation (chemical conditioning)
 Flocculation (physical conditioning)

Sedimentation
Sedimentation
Removal of largest particles for increased filtration
run times
 Achieves about 1-log removal (90%) of particles
 Extra buffering for raw water upset
 Required in treatment of many surface waters

Mechanism and Types of
Sedimentation
Physical treatment process that utilizes gravity to
separate solids from liquids
 Types of sedimentation

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Type I: discrete settling (i.e., settling of silt; presedimentation)
Type II: flocculant settling (i.e., coagulated surface water)
Type III: hindered settling/zone settling (i.e., upper
portion of sludge blanket in sludge thickener)
Type IV: compression settling (i.e., lower portion of a
gravity sludge thickener)
Media Filtration
Gravity filters:
• 2-3 m head
• housed in open concrete or
steel tanks
• large and small systems
Pressure filters:
• higher head
• housed in closed steel vessels
• costly; small systems
Granular Media Filtration Theory

Particles being captured can be 100-1,000 times
smaller than the pores
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Obviously not straining
Mechanisms of Filtration
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Transport to the Media Surface
Attachment
Transport Mechanisms During
Granular Media Filtration
A.
B.
C.
Sedimentation
Interception
Brownian Diffusion
A
Collector
B
C
Disinfection – Chlorine/ClO2
Water Stability
Water Stability

Tendency to either dissolve or deposit certain
minerals in pipes, plumbing, and appliance surfaces:
Water that tends to dissolve minerals  CORROSIVE
 Water that tends to deposit minerals  SCALING

Water Stability - Corrosion
Loss of an electron of metals reacting with water or
oxygen
 Corrosive chemicals include the following classes:

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acids
bases ("caustics" or "alkalis")
dehydrating agents (e.g., phosphorus pentoxide, calcium
oxide)
halogens and halogen salts (e.g., bromine,
iodine, zinc chloride, sodium hypochlorite)
organic halides and organic acid halides
acid anhydrides
some organic materials such as phenol
Water Stability - Corrosion

Adverse effects:


Dissolve Ca and Mg but also harmful to metals (lead &
cupper)
Regulation require utilities to test dissolved lead and
copper in drinking water

 treatment technique
Water Stability - Corrosion
Water Stability - Scaling
Saturation conditions
 Deposition of mineral film
 Some scaling is good to prevent
corrosion of metallic surfaces
 Excessive buildup (i.e., CaCO3, CaSO4)
 Rapid deposition:
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Damages appliances (water heaters, laundry
machines, dish washers…)
Increases pipe friction
Clogs pipes
Water Stability – Saturation Index
Calculations

Langelier Saturation Index (LSI)
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LSI = pH – pHs
pH: measured pH of water
pHs: pH at CaCO3 saturation
pHs = (pK2 – pKs) + pCa2+ + pAlk
calcium and alkalinity are in mol/L
 pK2, pKs – constants dependent on TDS and
temperature of the water

Water Stability – LSI Measurement

Langelier Saturation Index (LSI)

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LSI = pH – pHs
LSI < 0  corrosive tendency
LSI > 0  scaling tendency
Desired LSI: 0 to +0.2
Limitations - magnitude does NOT
indicate severity of the tendency!
Classwork
Determine if the following water has a corrosive or scaling
tendency:
Ca2+ = 1.05x10-3 M
Alkalinity = 1.2x10-3 M
TDS = 120 mg/L
pH = 7.73
Temperature = 10 C
Water Stability – RI Measurement
Ryznar Index (RI)
 RI = 2pHs – pH
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< 5.5 = heavy scale formation
5.5 - 6.2 = some scale will form
6.2 – 6.8 = non-scaling or corrosive
6.8 – 8.5 = corrosive water
> 8.5 = very corrosive water
Classwork
Determine if the following water has a corrosive or scaling
tendency:
Ca2+ = 1.05x10-3 M
Alkalinity = 1.2x10-3 M
TDS = 120 mg/L
pH = 7.73
Temperature = 10 C
Treatment Options to Enhance
Water Stability

Corrosive water

increase pH
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add hydrated lime Ca(OH)2
add soda ash Na2CO3 or NaOH
Scale forming water

lower pH
add acid
 recarbonation – add carbon dioxide
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sequestering agents (i.e., polyphosphates)
softening to remove calcium and magnesium
Regulations and
Water Quality Standards
Federal Requirements
 State regulations
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Golden WTP: Level III Partnership for Safe Water Quality

The Partnership for Safe Water is a voluntary effort that encourages public
water systems to survey their facilities, treatment processes, operating
and maintenance procedures, and management oversight practices. It is
geared toward filter plants that obtain source water from reservoirs, lakes,
rivers and streams. The Partnership’s goal is to provide a new measure of
safety. The program’s self-assessments identify areas that will enhance the
water system’s ability to prevent entry of Cryptosporidium, Giardia and
other microbial contaminants into the treated water. At the same time,
system staff can voluntarily make corrections that are appropriate for the
water system. In essence, the preventative measures are based on
optimizing treatment plant performance and thus increasing protection
against microbial contamination in the state’s drinking water supplies.
Regulations and
Water Quality Standards

Federal Requirements
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0.3 NTU (95%) not to exceed 1
Fe: secondary maximum contaminant level: 0.3 mg/L
Mn: secondary maximum contaminant level: 0.050 mg/L

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Complaints received when Mn is > 0.015 mg/L
Golden WTP: Level III Partnership for Safe Water Quality
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0.1 NTU (95%) (15 minute intervals)
Strict SOP’s for Operations
Stringent Reporting Guidelines
2nd plant in State, 7th in the Nation
Clear Creek Watershed
Mn in Raw Surface Water in U.S.
(Source: WaterStats)
0.35
0.3
0.25
0.2
0.15
Golden’s Current
Avg. Mn = 0.15 - 0.20
0.1
0.05
0
0
5
10
14
19
24
28
33
38
42
47
51
56
61
65
70
75
79
84
88
93
98
Average Mn Concentration,
m g/L
Avg_Manganese_(mg/L)_Raw_SW
Percentile
Manganese Chemistry

Potassium permanganate (KMnO4)

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MnCl2


chemical intermediate, catalyst, feed supplement, batteries
MnSO4


Oxidant, bactericide, algaecide, deodorizers, used to purify
drinking water, treat wastewater
fertilizer, varnishes, glazes, fungicide, nutritional supplement
MnO2

batteries, matches, fireworks, amethyst glass, chemical
intermediate
Manganese Chemistry

Divalent manganese is a reducing agent

Can lose electrons - become oxidized

Tetravalent manganese is a good oxidising agent

Heptavalent manganese is a powerful oxidising agent

Can gain electrons - become reduced
Manganese Chemistry
Reactions of Manganese Compounds

Metal


Oxidizes superficially in air, rusts in moist air
Dissolves readily in dilute mineral acids
Mn(s) + 2H+  Mn2+ + H2

Oxides

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Most stable MnO2 – Manganese dioxide
Lower oxides basic – MnIIO, MnIII2O3
Higher oxides acidic – MnIVO2, MnVII2O2
Manganese Chemistry
Reactions of Manganese Compounds
oxidant
Reaction
Oxidant
needed,
mg/mg
Mn2+
Alkalinity
used,
mg/mg
Mn2+
Sludge
produced,
kg/kg
Mn2+
O2
2MnSO4 + 2Ca(HCO3)2 + O2  2MnO2 + 2CaSO4 + 2H2O + 4CO2
0.29
1.80
1.58
Cl2
Mn(HCO3)2 + Ca(HCO3)2 + Cl2  MnO2 + CaCl2 + 2H2O + 4CO2
1.29
3.64
1.58
ClO2
Mn(HCO3)2 + 2NaHCO3 + 2ClO2  MnO2 + 2NaClO2 + 2H2O + 4CO2
2.46
3.64
1.58
KMnO4
3Mn(HCO3)2 + 2KMnO4  5MnO2 + 2KHCO3 + 2H2O + 4CO2
1.92
1.21
2.64
Manganese Chemistry
Reactions of Manganese Compounds
Although the mechanism of Mn reaction is not understood
completely, the following general expression may be used to
describe the oxidation in a Completely Mixed Batch Reactor:
-
[
d Mn2+
dt
] =k
[Mn ] + k [Mn ] [MnO (s)]
1
2+
2+
2
2
K1, k2 = rate constants of oxidative and autocatalytic pathways, respectively
[Mn2+] = aqueous-phase manganese ion concentration, mol/L
[MnO2(s)] = manganese oxide precipitate concentration, mol/L
Manganese Chemistry
Reactions of Manganese Compounds
An alternative rate expression has been presented for the
oxidation of Mn2+ to MnO2 using potassium permanganate:
-
[
d Mn2+
dt
] =k
[Mn ] [KMnO ] [OH ]
1
-
2+
4
1.1
([
] [
+ k 2 Mn2+ - Mn2+
] ) [MnO (s)]
e
2
K1 = rate constants of oxidative pathway, 9.55x1012 s-1(mol/L)-2.1
[Mn2+] = aqueous-phase manganese ion concentration, mol/L
[KMnO4] = aqueous-phase KMnO4 concentration, mol/L
[OH-] = aqueous-phase hydroxide ion concentration, mol/L
k2 = rate constants of autocatalytic pathway, 8.7x103 s-1(mol/L)-1
[Mn2+]e = aqueous-phase Mn2+ ion concentration in finished water, mol/L
[MnO2(s)] = manganese oxide precipitate concentration, mol/L
Measures to Improve
Manganese Removal

Lower Mn levels can be achieved by
adsorption/oxidation process (“Greensand”
filtration) than through particle removal
Natural negative surface charge
Mn
- Filter Media Mn
+
2
HOCl
HOCl
Mn2+
Mn2+
HOCl
Mn2+
Mn2+
HOCl
+
2
Mn2+
HOCl
Mn2+
HOCl
HOCl
Mn2+
Mn2+ + HOCl + H2O <-> MnO2(s) + Cl- +3H+
Measures to Improve
Manganese Removal

Mn levels in Clear Creek too high during Spring runoff for adsorption/oxidation to be fully effective
(need to be < 0.5 mg/L)

Multiple Barrier Approach

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
Pre-oxidation to create Mn precipitates
Coagulation, Floc/Sed and filtration to remove Mn
precipitates
Pre-chlorination across filters to polish Mn removals via
adsorption/oxidation process
Oxidation followed by
Adsorption & Filtration
Step 1: Add enough oxidant to oxidize a portion of the
Mn – allow some to stay in soluble form
FILTRATION
SOURCE WATER
RESERVOIR
CONVENTIONAL TREATMENT:
MIXING, FLOCCULATION, &
SEDIMENTATION
Step 2: Particles removed
via standard conventional
treatment
FINISHED
WATER
RESERVOIR
DISTRIBUTION
SYSTEM
Maintain free chlorine residual
Step 3: Soluble Mn removed via adsorption onto filter media.
Add chlorine onto filters, this “regenerates” media and allows for
continued adsorption
Viable Oxidants

KMnO4 (1.44 mg per mg Mn)

ClO2(g) (0.49 mg per mg Mn)

Cl2(g), or HOCl (1.29 mg Cl2 per mg Mn)
KMnO4 as Oxidant of Choice
Fast reaction times at high pH (>8)
 Overfeeding can cause colored water and higher Mn
concentration
 Liquid Concentrate



Continuous feeding pump that can
be flow paced
Solid Chemical Mixer
KMnO4 and Cl2 Dosing Strategies
Deliberately “Under Dose” KMnO4 to prevent pink
water and leave final polishing to adsorption/
oxidation process
 Set KMnO4 to 80-90% of stoichiometric dose
 Target 0.10 mg/L KMnO4 to ensure no pink color in
finished water
 Feed enough Cl2 ahead of filters to assure >1.0 mg/L
residual in finished water and maintain high Mn/Fe
adsorption affinity of MnO2 coating

KMnO4 and Cl2 Dose Requirements
0.94 mg KMnO4 per mg of Fe+2
 1.92 mg of KMnO4 per mg of Mn+2

0.62 mg Cl2 per mg of Fe+2
 1.27 mg Cl2 per mg of Mn+2

KMnO4 reacts fast (seconds/minutes)
 Cl2 reacts more slowly (hours)

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