Welcome to the
21st Century Distribution System
Onno Koelman
BSME, Stanford University
Focus on Tanks
Treatment plant
Distribution Piping
Tanks
Welcome to the 21st century
treatment site
(Boost) (Improve)
Maintain
Mixing
RCS Reservoir Control System
TRS THM Removal System
Three New Technologies for Managing the Distribution System
Audience – Who are you?
Cl en Pwt
RCS Reservoir Control System
TRS THM Removal System
Three New Technologies for Managing the Distribution System
Mixing
EPA’s Stage II looks for hotspots
Problem!
Problem!
Tanks
Sample points
Tanks might store 50% of your water.
Tanks might store 50% of your water.
Problem: They’re vulnerable …
Problem: They’re vulnerable …
Tanks might store 50% of your water.
3 Problems with Tanks
2. Water Age due
sun exposure
1. Water Age due
lack of turnover
3. Water Age due
short circuiting
Cl2 Cl2 Cl2 Cl2 Cl2 Cl2
Worst Water Quality
1. Low Turnover & Hydraulic Dead Zones
• Future build-out needs • Hard to expand later • 30% sized for fire flow • Seasonal demands change
Tanks are usually OVER-SIZED during design
2. Persistent Thermal Stratification
Many tanks… • have common inlet/outlets • are exposed to sunlight • fill with cold water
How does stratification happen?
Tank fills …
How does stratification happen?
Sun warms tank …
How does stratification happen?
Hot water rises …
Cool water drains out …
Strong and persistent thermocline established
Cool water fills tank …
Cool water drains out … again. Top water is now getting older
Cool water fills at night … again Top layer floats like a piston, still not mixed
?@$#!!
Deep cycling may not fully disrupt this thermal layer One day, too much demand Bad sample reading Customer complaints, biofilm, etc
Bad sample
Customer Complaints
Deep cycling is NOT a mixing solution…
10
15
20
25
30
Wat
er
leve
l [ft
]
12
14
16
18
20
22
tem
pe
ratu
re [
C]
0
0.5
1
1.5
2
2.5
7/2 7/4 7/6 7/8 7/10 7/12 7/14 7/16 7/18 7/20
Ch
lori
ne
[m
g/L
]
Top
Middle
Bottom
Water level cycled 60%
Tank remained stratified Float temp
Bottom temp
Thermocline
Inlet Outlet
Older water
Fresh water
Beware Seasonal “Inversions”
Winter: Snow/cool air cools the tank
Upper water cools, then “sinks” to the bottom
Worst water leaves tank first …
Summer: Sun/warm air heats the tank
→ Customer Complaints → Surprise Bac-T samples
“Optimistic” Sample ~1% of tank
Why do regulators recommend mixing?
How did we deal with this problem?
Dose
Flush
Juggle
• Manual • Spot-treatments • Reactionary • Not “management”
Cl2 Cl2 Cl2
Cl2
Cl2 Cl2
Cl2
Innovation for operators
Treatment plant
Tanks
Tanks
time
Chlorine
Install Mixers 1) Water Age reduced 2) Residual decay slows 3) Consistency
Residual with mixer
Baseline: Residual with NO mixer Water Age
time
30% Reduction in Chlorine At Treatment Plant
Residual with mixer
Baseline: Residual with NO mixer
Chlorine
Treatment plant
How much mixing does my client need?
Depends on shape and size of tank
– Small, flat tanks
– Large flat tanks, square tanks
– Standpipes (wide)
– Massive tanks (10 MG+)
– Standpipes (narrow)
Easy
Hard
Hard Easy
How much mixing does my client need?
Depends on what they are trying to do
– Maintaining well-mixed conditions
– De-stratification (thermal load)
– Blending a dose
– Aeration/Ice Prevention
Easy
Hard
THMs THMs
THMs THMs THMs
Hard Easy
But … what if mixing isn’t enough?
Mixing
TRS THM Removal System
Three New Technologies for Managing the Distribution System
RCS Reservoir Control System
PAX Reservoir Control System (RCS)
• Monitor chlorine
• Boost chlorine
• Intelligent controls to gradually feed
Residual Loss in Tanks
Many miles from the treatment plant ….
Treatment plant
Almost zero residual entering tank!
CL2
t
Range of Residual
in System
Residual Loss in Tanks
Many miles from the treatment plant ….
Treatment plant
Boost residual
CL2
t
Residual Loss in Tanks
Many miles from the treatment plant ….
Treatment plant CL2
t
Residual Loss in Tanks
Many miles from the treatment plant ….
Treatment plant
Boost residual
CL2
t
More consistent water throughout
system
Residual Loss in Tanks
Many miles from the treatment plant ….
Treatment plant
Boost residual
CL2
t
Fewer DBPs
More Control
Less Cost
Mixing + Chemical Injection
RCS Installation layout
RCS Installation layout
PAX Mixer
Injection
lines
Complete Mixing Flow Pattern with option for chemical addition onsite
Mixer 2. Optional chemical
injection line
1. Dose through hatch 3. Dose through center vent
Stabilize this tank at 1.5 ppm ALWAYS …
GREAT for Consecutive Systems
Stabilize this tank at 1.5 ppm ALWAYS …
GREAT when Purchasing Water
What is the PAX TRS?
hint: nothing to do with Star Trek
Mixing
RCS Reservoir Control System
Three New Technologies for Managing the Distribution System
TRS THM Removal System
Take control of your THMs
Option 1: Tackle at Treatment Plant
Option 2: Tackle in Distr. System
Tanks are a FREE air/water interface
THMs
THMs
THMs THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
At equilibrium, a
ratio in THM
concentration
between the air
and the water That ratio is the
Henry’s Law
constant
THMs are volatile …
Henry’s Law constants for THMs
Chloroform is the most “volatile”
(easiest to remove)
Confidential and Proprietary
THM species Henry's law constant
@ 20 C
Chloroform 0.13
Bromodichloromethane 0.08
Chlorodibromomethane 0.04
Bromoform 0.02
Bromoform is the least “volatile”
(hardest to remove)
Some aeration happens all by itself…
THMs
THMs
THMs THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
Poor mixing
prevents THMs
below the
surface from
escaping
Evaporation
stops
Diffusional
barrier
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs THMs
THMs
Powerful Mixing Enhances Aeration (5-10%)
Different In-tank Aeration Technologies
Bubble aeration Surface aeration Spray aeration
Any of these technologies can be made to work… but capital and energy costs vary greatly
Bubble aeration – How it works
Pop!
Air injected here
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
Surface Aeration – Mixing needed
THMs
THMs
THMs THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
Zone of THM removal
THMs trapped (mixing needed)
Spray Aeration
THMs
THMs
THMs THMs
THMs THMs
THMs
THMs
THMs
THMs THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
THMs
Pump
© 2011 PAX Water Technologies, Inc.
CFD for Tank Aeration Spraying
efficiency (X)
0
40
80
120
160
9/7/2010 9/8/2010 9/9/2010 9/17/2010
Entering the tank
Leaving the tank
Leaving the tank (Model)
THM [ppb]
Model shows accurate removal
What are the other options?
Treatment plant
Distribution System
GAC Reverse Osmosis
Enhanced Coagulant
Ozone Chloramines
UV PAX TRS
99% of the Money here ….
PAX Mixer
10x expense and multi-year projects
In summary …
Welcome to the 21st century
treatment site
(Boost) (Improve)
Maintain
Contact
• Teresa Corrington
• (253) 779-4160
• John Kitchen
• (503) 577-4194
PAX Mixer – The Active Solution
Mixer Details
• Stainless Steel 316
• Installs easily through hatch
• Sits on foot-pads, no attachment/scratching
• 60 Lbs, 4 feet tall
Power Source
• DC Motor
• 1/3 HP, $0.50/day
• Water-filled motor (no leaks)
• 5 yr warranty, 15 year expected life
PAX - Any Tank, Any Size
20 MGAL 9 MGAL 7 MGAL 1.5 MGAL 1.5 MGAL 0.2 MGAL
6 MGAL 3 MGAL 2 MGAL 2 MGAL 0.5 MGAL 1 MGAL 0.5 MGAL
Simple Installation
Motor power cable
Control Center
Tank Hatch
Biomimicry
Biology + Mimicry
Copy the high efficiencies found in nature
Biomimetic design of impeller
THM Removal Systems - Customized