Transcript Document

Activated Sludge Workshop
Techniques and Tools that Improve
Clarifier Performance
Mike Beattie
Operations and Reliability
Topics Today
• Troubleshooting:
• Develop a Robust
Operational Scheme
• Provide some simple things
to assist
• Can you run your plant
using only a settleometer?
• Diagnostics
• Limit Standard Deviation
• Limit changes on other
areas
• Avoid CTRL-ALT-DEL
• Fundamental biology vs.
Operating adjustments
Brown and Caldwell
2
My History 1992 Administrative Order
• Reduce overflows
• No more convenience
pressure relief
• Treat more/bypass less
• Would a clarifier that
could only treat 3 MGD be
of any use?
Brown and Caldwell
3
Seen it All
•
•
•
•
•
•
Foaming, Scum
Bulking
Solids Washout
Rising Sludge
Ashing
Straggler Floc
16 X 120 Clarifiers
• Plant could only handle 3 MGD
• Anything > = MASSIVE WASHOUT
Brown and Caldwell
4
Questions and Quest for Knowledge (The Grail)
• What causes all of these things to happen?
• What where the commonalities?
• The end result had to be a simple decision making tool
• Operators had to Understand Original Design Intent
(train, train, train, 21 conversations)
• SOR, Weir Overflow Rate, Solids Loading Rate, Solids
Under-loading Rate Nuances of settled sludge
• Too much or too little food results in poor sludge
quality
Brown and Caldwell
5
Needed to Understand Original Design Intent
and Changes
• Drawings
• Influent Distribution
• Baffles
• Pump Capacities
• Flow Meters
• Calibration
Brown and Caldwell
6
Drawing Review
• Found that the tanks
were built in 1956
• Original Primary Clarifiers
• Original operating depth
was 7 feet
• Institutional knowledge
was “ever since (1972)
we got that aeration basin
and those new primary
clarifiers these final
clarifiers have been
nothing but a problem”
Brown and Caldwell
1972
Grit Removal
Primary Clarifiers
Aeration Basin series/and parallel
Gas Storage Digester
Retrofit old primary clarifiers to finals
Disinfection
7
1978 Upgrade
Added Three Ponds
(did I mention our collection system 240 MGD)
Brown and Caldwell
8
Final Clarifiers-I (used to) Have Baffles
• Drawings Said Yes
• Tank Inspection=NO!
• Most taken out during
collector upgrade but not
replaced
• $3,000 fix
Brown and Caldwell
9
Influent Distribution
• Inspecting for debris is very helpful
• Sampling the entire water column?
• Could a sludge judge, some buckets and a little laboratory
work tell you anything?
• Proper Sludge Judge Use (ITA Study)
• Dye testing can be helpful
• CFD modeling can be helpful
Brown and Caldwell
10
Additional Efforts
• Quieted the entry of the
aeration basin effluent
(no waterfalls into
clarifier) mid-depth entry
is was best
• Adjusted influent gates to
even flow
• Leveled and set effluent
the weirs
• Bucket tests of the RAS
pumps
Brown and Caldwell
11
Design Issues Vetted-Next Step-Operate
• Identify all parameters
where someone could make
a decision, adjustment,
equipment on and off
• Calculate standard
deviation for the
parameters
• Found out RAS Flow
standard deviation was
200%
• MLSS standard deviation
was 1500 mg/L
• WAS Concentration similar
Brown and Caldwell
12
How does the tail wag the dog here?
• Can the operator directly
influence RAS TSS?
• How ??
• Can the operator directly
influence MLSS TSS?
• How ??
• Can the operator directly
influence WAS
parameters?
• How ??
Brown and Caldwell
13
The influences did not matter unless I
understood the goal: Quality sludge to get the
most out of our clarifiers!
What is Quality Sludge?
Activated sludge that:
• Flocculates
• Settles and filters
• Compacts
Brown and Caldwell
14
Learn the Blues Before You Learn How to Rock
and Roll
• Recommends Using the
Settleometer
• Recommends that RAS
Flow Control is Very
Important
• Discusses the concept of
different settling sludges
exist that can do the
same thing
Brown and Caldwell
15
What is SVI Really? Does SVI allow you to
measure• Flocculation?
• Settling?
• Compaction?
• What does Sludge Volume
Index have to do with any
of these?
• When is it done
flocculating, settling,
compacting?
Brown and Caldwell
16
Rate of Settling
• Sludge can settle at a
rapid rate
• Sludge can settle at a
normal rate
• Sludge can settle at a
slow rate
Brown and Caldwell
• All three types of sludge
can flocculate, settle and
compact
• All three can remove
enough BOD to meet
permit
• All three can perform well
in a clarifier
17
How Does RAS Concentration respond to
Changes in RAS Flow?
Brown and Caldwell
18
How does MLSS respond to changes in RAS
Flow?
Brown and Caldwell
19
How Do Solids Filter and Compact in the
Settleometer?
1000
900
800
700
600
500
400
300
200
100
0
0
50
100
Rapid
Brown and Caldwell
150
Normal
200
Slow
20
Recommendations from Al’s Work
• Collect more data during
settle test
• 5, 10, 15, 20, 25, 30, 60,
120, 180, 240 minutes
1000
900
800
700
600
500
• 5 minute-measures
settling
• 15 minute-filters
• 30 minute-compaction
400
300
200
100
0
0
50
100
Rapid
Brown and Caldwell
150
Normal
200
Slow
21
Use 5 minute reading on MLSS to Type
Less than 500

I have a Rapid Settling Sludge
500-900

I have a Normal Settling Sludge
900 or higher

I have a Slow Settling Sludge
Brown and Caldwell
22
Al Says - How do I know when its time to send
the bugs back to the aeration tank?
• The goal is to determine • RAS Settleometer Test
when is the RAS sludge
done settling, filtering and • Collect Data at:
compacting in the final
•
30
Minute
clarifier
• Spending the correct
amount of time in the
final clarifier allows much
better process control
Brown and Caldwell
• 60 Minute
• 120 Minute
23
Use 5 minute reading on MLSS to Decide RAS
Test
<500
 Rapid 
RAS at 30 Min
500-900
 Normal 
RAS at 60 Min
900 or higher
 Slow 
RAS at 60 Min
Brown and Caldwell
24
What Now?
• What kind of sludge
• Use appropriate RAS
Reading (30, 60 or 120
min)
• When RAS is at 900 its
done
Brown and Caldwell
• Is reading above or below
900?
• If above 900 RAS turn
RAS rate up 5-10%
• If below 900 turn RAS
rate down 5-10%
25
Remember My Plant?
Before
After
• No more than 3 MGD
• 13 MGD
• Massive solids loss during • Highest effluents out of
storm events
plant were 50 ppm
• Permit Anxiety
• Flow diverted to other
facilities
• Extreme STD DEV
Brown and Caldwell
• Reduced flow diversion by
85%
• MLSS STD DEV 300 mg/L
• RAS STD DEV 25%
26
If you can master this simple settleometer
technique
• Unlock hidden capacity
without adding any
concrete
• Reduce energy usage
• Nutrient removal
• UV disinfection
Your ready to rock and roll!
Brown and Caldwell
27
Questions??
Mike Beattie
Brown & Caldwell
Operations/Reliability
[email protected]
952-240-0341
Brown and Caldwell
28