1. LARGE BUBBLE
VERTICAL MIXING
Energy Savings and Performance Enhancement
LARRY L. BELL
V.P. SALES
PULSED HYDRAULICS INC.

2. Aeration is 54% of the Total Power Consumed
Aeration 54%Return Sludge
Pumping 0.46%
Gravity
Thickening 0.06%
Anaerobic
Digestion
14.24%
BeltPress 3.91%
Chlorination
Lighting&
Buildings 8.14%
Wastewater
Pumping 14.26%
Screens 0.02%
Grit1.26%
Clarifiers3.15%
Electrical Usage in WWTPs

3. AERATION BASIN MIXING
• PERHAPS THE MOST OVERLOOKED
ASPECT OF PROCESS TREATMENT !
• IF YOU ASK 10 PEOPLE WHAT IT IS, YOU
WILL PROBABLY GET 10 DIFFERENT
ANSWERS !

8. HORIZONTAL MIXING
• ANY MIXING SYSTEM THAT MOVES THE
LIQUID IN A HORIZONTAL PLANE IS NOT
REALLY MIXING……IT IS STIRRING !
• SOLIDS TEND TO ACCUMULATE ON THE
BOTTOM, IN THE CORNERS AND IN THE
MIDDLE OF THE STIRRING VORTEX !

9. HORIZONTAL MIXERS STIR … NOT MIX!

10. VERTICAL MIXING
• MIXING SYSTEMS THAT MOVE THE
LIQUID IN A VERTICAL PLANE TEND TO
INVOLVE THE ENTIRE VOLUME OF THE
TANK !
• LIFTING SOLIDS VERTICALLY USES THE
FORCES OF BUOYANCY AND GRAVITY TO
DISPERSE TANK CONTENTS MORE
EVENLY WITHIN THE TANK !

11. LARGE BUBBLE VERTICAL MIXERS USE
BUOYANCY AND GRAVITY TO EVENLY
DISBURSE SOLIDS

12. TYPES OF VERTICAL MIXERS
• 1. MECHANICAL
• 2. AIR
A. Continuous Flow
i. Fine Bubble
ii. Course Bubble
B. Pulsed
i. LARGE BUBBLE
ii. Small Bubble

13. MECHANICAL VERTICAL MIXER
1. MOVING PARTS IN THE TANK NEED MAINTENANCE
2. FLUID IS PULLED DOWN THE MIDDLE OF A MIXING ZONE
AND UP THE OUTSIDE THE MIXING ZONE EDGES.
3. ALL ENERGY USED HAS TO BE SUPPLIED EXTERNALLY.

17. Aeration Enhancement
Improving Nutrient Removal and
Energy Efficiency

18. The ultimate goal:
A. Lower Energy Costs
B. Improved Treatment Efficiencies
These can be achieved via an integrated solution:
1. Variable-speed high-efficiency blowers.
2. High efficiency diffusers.
3. Large bubble, vertical mixing system.
4. On-line instrumentation (automate the
blowers and mixing system)

20. TANK VOLUME RECOVERY BY
LARGE BUBBLE MIXING
SEOUL, SOUTH KOREA
• One Bubble Forming Plate per
30 foot square zone = 1-2 HP
• Achieved complete mixing in
each zone (< 2% TSS
variation from top to bottom)
• D.O. increased allowing blower
scfm to be lowered
• BOD / NH3 removal efficiency
improved allowing increased
loadings
• Final pilot plant paper due out
in February 2013

23. AERATION ENHANCEMENT
& ANOXIC MIXING

24. Innovative Equalization Tank and Mixing System
Eliminates SSOs, Improves Plant Performance,
and Saves Money
Project: Shelby County Lake Loramie WWTP
Wet Weather Flow Equalization Improvements
Presented by: Jeremy M. Cook, PE
URS Corporation – Columbus, Ohio

25. Mixing Systems Evaluated
• Coarse Bubble Diffusers  Submersible Propeller Mixers
 Submersible Jet Pumps
 Pulsed Air System

26. Submersible Propellor and Jet Pumps
 Simple Installation and No Blower Building
 Large Horsepower Requirements (approx. 120 HP) created by large tank
diameter (greater Thrust)
 Capital Costs: $150,000
 Electrical Cost: 120 HP @ $0.08/kwh for 90 days, 24 hr/day = $15,500

27. Coarse Bubble Mixing System
 2,500 scfm Centrifugal Blower (approx. 80 HP)
 200 SS Wide Band Diffusers
 Large tank diameter would have required a lot of SS pipe and diffusers
 Need a Blower Building or Enclosure
 Estimated Capital Cost: $300,000
 Electrical Cost: 80 HP @ $0.08/kwh for 90 days, 24 hr/day = $10,400

28.  Small Precast Building to house 20 HP Compressor, 240 gal.
Receiver, Solenoid Valves & PLC Controller.
 1”SS Piping and 40 Bubble Forming Plates
 Capital Costs: $100,000 (with building); saving $50,000
 Electrical Cost: 20 HP @ $0.08/kwh for 90 days, 24 hr/day =
$2,600; saving $12,900 /yr
 Manufacturer: Pulsed Hydraulics, Inc. (PHI)
Lake Loramie (OH) Sanitary District

29. EQ Tank

30. 45 FOOT DIAMETER SLUDGE
STORAGE TANK
POWER COST FORMULA
Cost = (bhp) x (0.746) x (hours) x (power
rate) / motor efficiency
Where: bhp (brake horsepower
power rate ($ per kilowatt hour)
Hours (operating hours)
motor efficiency (%)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
EXISTING BLOWERS AND COURSE AIR
DIFFUSERS :
75 HP operating 24 hours / 7 days per
week
Power Rate is $0.07 and Motor Efficiency
is estimated at 93%
(75) x (0.746) x (24) x ($0.07) / 0.93 =
$101.07 / Day ($36,890.90 per year)

31. LARGE BUBBLE VERTICAL MIXING
SYSTEM:
10 HP operating 24 hours / 7 days per
week
Power Rate is $0.07 and Motor Efficiency
System pulls 7 kw when operating on load
(not 7.46 kw if calculated 10 x 0.746 as in
above formula).
(7 kw) x (24) x ($0.07) / 0.93 = $12.65 /
Day ($4,617.25 per year)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
ANNUAL ENERGY SAVINGS =
$32,273.65
The above calculation for the large bubble
vertical mixing system was computed on
the basis of the mixing system operating
on load 24 hours per day / 7 days per week
utilizing the full 10 HP capacity of the
compressor. Actual operating HP has
been estimated to be 4.5 to 6 HP.

32. What are the mixing applications?
• Aeration / anoxic basins in WWTPs
• Sludge
• Polymer & Hypochlorite Chemical Storage Tanks
• Lift Station Wet Wells
• Flow Equalization Basins
• Elevated & Ground Level Water Storage Tanks
• Petroleum Storage Tanks (Vented)
• Foods and Beverages (Wine – Whiskey)
• Any Liquid In A Vented Vessel or Tank

33. OTHER APPLICATIONS & VIDEOS
•GO TO WWW.PHIWATER.COM
•SELECT THE APPLICATION TAB
•SELECT THE APPLICATION OF
INTEREST
•WATCH A VIDEO OF MIXING
OCCUR OR DOWNLOAD THE
APPLICATION LITERATURE

34. Duration
Pulses Per
Minute
CFM
Required Input kW
CFM
Per Pulse
.3 seconds 2 times 3.4 CFM 0.97 kW 1.7 CFM
.4 seconds 2 times 4.9 CFM 1.42 kW 2.5 CFM
.5 seconds 2 times 5.5 CFM 1.57 kW 2.8 CFM
How much air is used ?