Kansas Water Environment Federation

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Kansas Water Environment Federation

• April 11, 2006
• Betsy Betros
• Johnson County Environmental Department

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Some Unusual Slimy, Gooey,Yuckies in
Collection Systems
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The on-going saga that started with.
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Severe blanket problem in the wetwell of a lift
station which was thought to be grease.
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This investigation started in early 2004, when
increased concerns about FOG(Fats, Oils and
Grease) problems at a lift station and in the
collection system at the New Century AirCenter in
Johnson County were reported to us.
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The lift station is one of several which pumps to
a small, heavily industrialized WWTP, extended
aeration activated sludge.
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With two food producers upstream

• It seemed a no brainer they were the cause.

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and they were, but.

• Not quite for the reasons we originally assumed
  which was grease!

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Sample collected of the blanket yielded 4 FOG.
If goo floating on top was all greasewould
expect a considerably larger number.
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What was thought to be severe grease deposits in
the collection system turned out to be biofilm
and was traced to a food industry.
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pH tank
Industry reported, they had battled a biofilm
problemwhich at first look didnt seem like
much, but then.
pH neutralization following DAF
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this is what was the really BIG problem with
biofilm!
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So how did we determine it was biofilm in the
sewer?Culturing and identifying unknown
biological growth was just a wee bit beyond our
abilities..
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So, how about a sample to look at?
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Manhole 3 showing scraper and pick up device.
August 16, 2005.
Flow
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And once the biofilm was controlled.did the
problem at the lift station go away and were we
all happy?
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Still having troubles with lift station, to the
point they were pumping it out nearly weekly.
Nope!
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Part 2
Whats still filling up the lift station?
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March 31 2005 wetwell
Sojust what is making up this blanket of
floating goo??
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The blanket of floating goo in the lift station
was reported to be very dense.
June 3 2005

• Tried using a Peterson dredge to collect sample.

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Dredge went straight through, so switched to
bucket.
35 feet deep
June 3 2005
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Stirred the blanketup in water
Blanket Sample
and it sunk!
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Paper Fiber
Diluted sample down to reveal the primary
constituent is paper fiber!
June 3 2005
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TP Fiber through the microscope
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Some grease did separate, but certainly not the
main constituent of the blanket.
May 25 2005
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And why did it sink?
But why was the TP floating?
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Can we simulate the conditions in the wet well in
a bench scale test?
May 20 2005
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Could it be due to products or raw ingredients
from any of the upstream companies?
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June 3 2005
TP by itself, did not float, even with or without
agitation.
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Both vegetable oil and mineral oil immediately
came out of oil-soaked TP when put in water.
And the TP sunk
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TP Margarine separated quickly when put in
water
Oil by itself was not causing the TP to float.
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So what about other combinations?TP Water
Egg white did float out TP nicely.
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TP Water egg yolk did not float out TP
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Even though the egg white floated the TP, the
problem was constant, so unlikely a company was
losing that much egg white.

• But certainly begged the question as to what
  else in the food world could be floating the TP.

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Nextadded oil to the mixture, and.both yolk and
white plus oil floated TP easily. So, perhaps oil
was a contributor in a mixed environment.
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So, tested more combinations
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Didnt float out TP.
June 6 2005
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Added vegetable oildid float out TP easily,
combined with other ingredients.
Except TP and oil only.
June 6 2005
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Nextwhat other ingredients on a continual basis
could be contributing?

• What about the DAF chemicals? The 2 DAF
  discharges made up a significant percent of the
  flow to the lift station. But of course, all used
  different chemicals!
• Was it from only one, or a combination of one or
  both facilities?
• Did test various ingredients without any
  floating TP.

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Tried the polymers used in the DAFs from both
facilities.
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DAF effluent from one industry would float TP
sometimes and sometimes not.
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Starting looking as if the DAF effluents were
significant contributors to the floating TP
problem.
Another WWTP influent, didnt float TP.
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Looked at cleaning agents.
One cleaner did float out TP, but it wasnt used
daily and it took a lot and was pH dependent.
Dirtied floor cleaner from one industry really
floated TP, but floor cleaner from another did
not.
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Still the main denominator was the DAF effluents.

• One industry had made significant flow changes in
  their processso we asked them if they had
  adjusted their DAF chemicals.
• Nope.they are now saving a lot of money.
• The consistency of the blanket softened after
  they adjusted the chemicals.

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A big issue now presented itself

• Three industries with properly performing DAF
  systems which looked like they were the chief
  culprit in the floating TP problem.
• The nature of DAFs is to float out the grease and
  it turns out, the chemicals float out TP real
  nicely as well.
• Do we make them change their systems?

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Millions of dollars of investment into the
properly functioning DAFs made this scenario
unlikely

• Since the blanket was primarily paper fiber,
  presumably toilet paper, then could agitation be
  added to the wet well to keep it from forming?

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It had been noted that during high rains

• That high inflow and agitation at the lift
  station flushed out/prevented blanket formation.
• Hummm.

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Wastewater Department added a chopper pump which
activates each time the pumps kick on. The
blanket still forms, but no longer presents a
problem.
October 21, 2005
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As it was previously, interfering with sensors.
Aug 13 2004
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Summary What originally appeared to be a no
brainer investigation, turned into an extensive
and exhaustive investigation into a two fold
problem Extensive biofilm growth in the
collection system. Floating toilet paper in a wet
well.
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What can be done beyond what has been???

• Both problems associated with food producers and
  DAFs, a standard and very effective treatment
  method for large quantity grease removal.
• Flow into a lift station predominated by
  discharges from 3 DAFs, designed to flocculate
  grease, but also apparently able to flocculate
  paper fibers!

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