Activated Sludge WorkshopTechniques and Tools that Improve Clarifier PerformanceMike BeattieOperations and Reliability

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• Troubleshooting:• Provide some simple

things to assist• Can you run your plant

using only a settleometer?

• Diagnostics• Fundamental biology

vs. Operating adjustments

Topics Today• Develop a Robust Operational Scheme• Limit Standard

Deviation• Limit changes on other

areas• Avoid CTRL-ALT-DEL

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• Reduce overflows• No more convenience

pressure relief• Treat more/bypass

less• Would a clarifier that

could only treat 3 MGD be of any use?

My History 1992 Administrative Order

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• Foaming, Scum• Bulking• Solids Washout• Rising Sludge• Ashing• Straggler Floc

• Plant could only handle 3 MGD• Anything > = MASSIVE WASHOUT

Seen it All

16 X 120 Clarifiers

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• 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

Questions and Quest for Knowledge (The Grail)

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• Drawings• Influent Distribution• Baffles• Pump Capacities• Flow Meters• Calibration

Needed to Understand Original Design Intent and Changes

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• 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”

Drawing Review

1972 Grit Removal

Primary ClarifiersAeration Basin series/and parallel

Gas Storage DigesterRetrofit old primary clarifiers to finals

Disinfection

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Added Three Ponds(did I mention our collection system 240 MGD)

1978 Upgrade

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• Drawings Said Yes• Tank Inspection=NO!• Most taken out during

collector upgrade but not replaced• $3,000 fix

Final Clarifiers-I (used to) Have Baffles

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• 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

Influent Distribution

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• 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

Additional Efforts

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• 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

Design Issues Vetted-Next Step-Operate

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• Can the operator directly influence RAS TSS?• Can the operator

directly influence MLSS TSS?• Can the operator

directly influence WAS parameters?

How does the tail wag the dog here?• How ??

• How ??

• How ??

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What is Quality Sludge?Activated sludge that:• Flocculates• Settles and filters• Compacts

The influences did not matter unless I understood the goal: Quality sludge to get the most out of our clarifiers!

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• 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

Learn the Blues Before You Learn How to Rock and Roll

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• Flocculation?• Settling?• Compaction?• What does Sludge Volume Index have to do with any of these?• When is it done

flocculating, settling, compacting?

What is SVI Really? Does SVI allow you to measure-

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• Sludge can settle at a rapid rate• Sludge can settle at a normal rate• Sludge can settle at a slow rate

Rate of Settling• 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

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How Does RAS Concentration respond to Changes in RAS Flow?

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How does MLSS respond to changes in RAS Flow?

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How Do Solids Filter and Compact in the Settleometer?

0 50 100 150 2000

100

200

300

400

500

600

700

800

900

1000

Rapid Normal Slow

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• Collect more data during settle test• 5, 10, 15, 20, 25, 30,

60, 120, 180, 240 minutes

• 5 minute-measures settling• 15 minute-filters• 30 minute-

compaction

Recommendations from Al’s Work

0 50 100 150 2000

100

200

300

400

500

600

700

800

900

1000

Rapid Normal Slow

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Less than 500

500-900

900 or higher

Use 5 minute reading on MLSS to Type I have a Rapid Settling Sludge

I have a Normal Settling Sludge

I have a Slow Settling Sludge

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• The goal is to determine when is the RAS sludge done settling, filtering and compacting in the final clarifier• Spending the correct

amount of time in the final clarifier allows much better process control

Al Says - How do I know when its time to send the bugs back to the aeration tank?

• RAS Settleometer Test•Collect Data at:• 30 Minute• 60 Minute• 120 Minute

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<500 Rapid RAS at 30 Min

500-900 Normal RAS at 60 Min

900 or higher Slow RAS at 60 Min

Use 5 minute reading on MLSS to Decide RAS Test

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• What kind of sludge• Use appropriate RAS

Reading (30, 60 or 120 min)• When RAS is at 900

its done

What Now?• 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%

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Before• No more than 3 MGD• Massive solids loss

during storm events• Permit Anxiety• Flow diverted to

other facilities• Extreme STD DEV

Remember My Plant?After• 13 MGD• Highest effluents out

of plant were 50 ppm• Reduced flow

diversion by 85%• MLSS STD DEV 300

mg/L• RAS STD DEV 25%

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• Unlock hidden capacity without adding any concrete• Reduce energy usage• Nutrient removal• UV disinfection

Your ready to rock and roll!

If you can master this simple settleometer technique

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Questions??

Mike BeattieBrown & Caldwell

Operations/Reliabilitymbeattie@brwncald.com

952-240-0341