Metal hits at wwtp s
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"Metal Hits at WWTP’s. Class ”A” EQ Biosolids To Class “F” And Back Again. Class “B” tertiary treatment plant Grit removal Primaries Aeration tanks Secondary's RBC Sand filters Anaerobic digesters Discharge into trout stream. Cadillac WWTP. Microscopic Evaluation Hauling Biosolids

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Metal hits at wwtp s

"Metal Hits at WWTP’s

Class ”A” EQ Biosolids

To Class “F”

And Back Again

Cadillac wwtp

Class “B” tertiary treatment plant

Grit removal


Aeration tanks



Sand filters

Anaerobic digesters

Discharge into trout stream

Cadillac WWTP

The story

Microscopic Evaluation

Hauling Biosolids

Point Source Study

Wet Test

We Have a problem

Confirm Tests


Incoming Trunk lines


On the trail of the Guilty

Sampling Trailer

The Story

Story continued

Guilty Party

The Meeting


Toxic Sludge



Geotubes II



Story (continued)

Microscopic evaluation
Microscopic Evaluation

  • Evaluate three Activated sludge slides a day

  • Noticed decrease in life on Mondays

  • Increased life all week

  • Decreased life next Monday

  • Life in tanks are not stable

  • Begin trying changing operations.


  • Five years of study for class “A” EQ status

  • Sent in application for certification

  • Received certification

  • Applied 1st time as Certified Class ”A” EQ

  • Emptied both biosolids tanks(800K &700K)

Point source study
Point Source Study

  • DEQ show up to do Point Source Study

  • Everything appears to be normal

  • Received a phone call on biosolids

  • Sample of digester #1 to #2 transfer is Hot!

  • Zinc Level shows 6010mg/L

  • Are our numbers right?

Wet test
Wet Test

  • Sent in WET test sample to ASCI Lab.

  • Before second sample get call

  • Everything is dead in 100%/66% samples

  • What is happening

  • Sodium thiosulfate remaining sample

  • No die off.

  • Heavy metal present.

We have a problem
We have a problem

  • Low bug populations

  • High zinc level in Point Source biosolids

  • Toxicity caused by heavy metal

  • Better find out what’s wrong

Confirm tests
Confirm tests

  • Do we have or had a problem?

  • Start testing influent & effluent daily

  • Internal Testing lab.

  • Test seven days a week

  • Start testing Digester solids

  • What for results to see what we will do.


  • We have a problem

  • Start testing trunk lines & plant

  • Start testing industries on a more frequent basis.

  • Two Isco Samplers plus Plant Sampler

  • Hard to test and keep IPP program to date

Incoming trunk lines
Incoming Trunk Lines

  • Four Trunk lines Converge at WWTP

  • Able to test each line on plant ground

  • Narrowed down to two trunk lines

  • Investigated further- One trunk line now

  • Our most Industrial trunk line.

  • Also had Major county flow in it


  • Many Industries on line plus county.

  • Must eliminate one at a time. County first

  • Military Pallets

  • Rubber Factories

  • Boat manufacture

  • Power plant

  • Foundry

On the trail of the guilty
On the Trail of the Guilty

  • Always Chasing tail

  • Couldn’t find guilty party

  • Had Industry that was retrofitting Cooling tower at the correct time. Not guilty

  • Only one industry never had a hit at plant while we were sampling it.

  • Couldn’t catch.

Sampling trailer
Sampling Trailer

  • Sampling trailer Problem?

  • Great deterrent

  • Community Awareness

  • Industry Tip Off ??

Guilty party
Guilty Party

  • Have idea who is guilty party can’t prove

  • Sampled 1 1/2 weeks straight no upsets

  • Moved over weekend/Had upset

  • Tested a week longer. No upsets

  • Moved and then hid the sampler

  • Had “hot” sample from industry

  • Should have known it was the Foundry

The meeting
The Meeting

  • Called Industry about problem

  • Set meeting date

  • Found out they had been experimenting

  • Oil cans and Soup cans

  • pH in treatment system very low

  • Kept zinc soluble

  • Very hard on equipment


  • Never said the word Zinc

  • Never admitted to wrong doing

  • Offer to help pay for cleanup

  • Doing this out of sense of community

  • They would help us

  • They were hoping we would help them

  • Set up extra monitoring and limits

Toxic sludge
Toxic Sludge

  • Now that problem taken care of what do we do with sludge.

  • Store all in one tank

  • Keep adding until level falls below ceiling

  • Start filling second tank with Class “B”


  • Decided to put out to bid

  • Six bidders

  • Three within 8/10 of a cent

  • One of low bidder was our own hauler

  • Council went with Low bid

  • Was an application not familiar with


  • Fill tubes with sludge

  • Add polymers

  • Sludge will dewater

  • Tubes will weep

  • Add more sludge

  • Repeat until tubes are filled

  • Wait until dry

Geotubes ii
Geotubes II

  • Filled tubes

  • Suppose to be 2 tubes

  • Became 5 tubes

  • Needed more polymer

  • More space

  • Time,time,time


  • Never dried fully

  • Add sawdust

  • Take to landfill

  • Increased landfill rates

  • More cost and time

  • Pleasantly surprised contractor stayed .


  • Be vigilant

  • Test often

  • Test on weekends

  • Be prepared

  • Work with industry

  • Want to keep industry not drive away