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New interest in corrosion control and phosphates
Outline
2 Water Treatment Process
1 Understanding Corrosion
3 Corrosion Control Treatment Options
4 Optimizing Corrosion Control
Water source at a glance
5
Surface water
Ground water
Water source
New Study of U.S. Geological Survey about corrosivity of groundwater
► 25 states have groundwater that has either high or very high potential to be corrosive
Map
: pub
lic d
omai
n by
USG
S (0
7/13
/16)
Water treatment process
www.instantMPY.com
Treatment Techniques:
•pH-Adjustment•Phosphate
?
Water source Treatment Measurement Distribution
Surface water
Ground water Finished water quality
Corrosion Control Overview
7
Treatment Techniques
► pH Adjustment
► Lime
► Soda Ash
► Caustic Soda
► Corrosion Inhibitor
► Zinc Phosphate
► Blended Phosphates
► Silicates
NaOH
OH2
Na2CO3
Zn
PO4
Na2SIO3
Polyphosphate Benefits
Sequestration of minerals
► Mechanism:
Polyphosphate content
bonds with calcium
hardness, iron and
manganese.
► Result:
Mineral is maintained in a
clear, soluble state.
Scale control
► Mechanism:
Polyphosphate content
interrupts scale formation
by affecting crystal growth
of scale.
► Result:
Scale and deposits are
reduced.
Orthophosphate Benefits
Corrosion control
► Mechanism:
Orthophosphate content combines with hardness in water
to form a barrier film on all metal surfaces.
► Result:
Corrosion rates are reduced.
Two Groups of Blended Phosphates
Blended Polyphosphates/Orthophos
phates
ZincOrthophosphates
► Sequestration of minerals (Fe, Mn, Ca)
► Corrosion Control
► Corrosion control only
► pH sensitive (7.2 - 8.0 operating range)
Understand Drinking Water Quality Characteristics
Water Quality Parameters for Corrosion Control Recommendations
► Finished pH► Finished Alkalinity ppm► Finished Hardness ppm► Finished Iron ppm► Finished Manganese ppm
► Plant Flow MGD► Historical Data
Blended Phosphates
0%
25%
50%
75%
100%
0% 100%50% 75%25%
Ort
ho p
erce
ntag
e
Poly percentage
High Polyphosphate
High Orthophosphate
Measurement methods at a glance
PROACTIVE TechnologyREACTIVE Technologies
Water Quality Sampling
Corrosion Coupons
LPR
Online Monitoring
► Average value► Long test time► Labor intensive► Small sample
size
► One value► Short test time► Labor intensive► Small sample
size
► Continuous measurement
► Instant test time► Minimal labor► Large sample size
Corrosion rates are always changing
0123456789
10
Jan Feb Mar Apr May Jun Jul AugSep Oct NovDec Jan Feb Mar
Corrosion rate in mils per year
Factors influencing corrosion
► Water quality changes► Temperature► pH-values► Dissolved oxygen► Blends of finished water
Corrosion rate of a Southeastern US surface water system
Conclusion
► Need for instant monitoring► Adjustment of corrosion
inhibitor
How real time corrosion monitoring works
Linear Polarization Resistance
► Small electrical charge through the
probes
► Resulting current is measured
► Polarization resistance is ratio of
► Applied electrical charge and
► Resulting current measured
► Resistance is inversely related to
the corrosion rate
(𝐿𝐿𝐿𝐿)𝑅𝑅𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤=
𝑈𝑈𝑤𝑤𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑤𝑤𝑎𝑎𝐼𝐼𝑚𝑚𝑤𝑤𝑤𝑤𝑚𝑚𝑚𝑚𝑤𝑤𝑤𝑤𝑎𝑎
𝐶𝐶𝑅𝑅𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤=
1𝑅𝑅𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤
Summary and Outlook
Benefits of using LPR
► Monitor drinking water corrosion rates on a real time basis► Corrosion rate is continuously measured and displayed► Optimize corrosion chemical feed rates and pH adjustment► Corrosive conditions are detected before water enters distribution system
Water source
Treatment Measurement Distribution
Adjustment of corrosion control
Optimization of corrosion control
Questions or Comments
Answers
Questions
Contact Information
• John Walsh InstantMPY• 2010 Sterling Rd, Charlotte, NC 28209• 704.905.8624• [email protected]• www.instantmpy.com
