Andy Aiken aaikenaqua'org

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Use of Foam Fractionation for Improving Water
Quality in Marine Aquaria
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Topics to Cover

• Dissolved Organic Matter (DOM)
• Source
• Characteristics
• Effects of on WQ
• Foam Fractionation
• Removal of DOM
• Disinfection
• Particulate removal
• Ozones role in FF
• Placement of FF within the LSS

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Dissolved Organic Matter (DOM)
In the water column, excess food and animal
wastes degrade into particulate, semi-solid and
dissolved organic matter. Much of the
semi-solid and DOM disintegrates, forming
long-chain organic molecules that cannot be
mechanically filtered.
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Natural Processing of DOM

• In natural waters, particulate and DOM become
• part of nutrient cycles
• Food source for phytoplankton
• Geologic and atmospheric element cycles
• Broken down by bacteria and other organisms.

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Accumulation of DOM in Aquarium LSS

• In a closed or semi-closed aquarium LSS, the
  major
• microbial processing of DOM is bacterial,
  primarily
• in sand filters and biofilters
• Assimilation of DOM into biofilms is slow
  (typically
• does not keep pace with loading).
• Assimilation of DOM into biofilms also produces
• deleterious effects of bacterial respiration
• Consumes Dissolved Oxygen (D.O.)
• Releases CO2 into the water column
• (produces carbonic acid, lowers pH)

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Net Effect of DOM Accumulation

• ? D.O.
• ? pH
• O.R.P.

? Oxidant Demand ? NH3, NO2, NO3 ? Need for Buffer
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DOM
Many long-chain organic molecules have a polar
(hydrophilic) head and one or more non-polar
(hydrophobic) tails
Polar head () and (-) charge
Non-polar tails
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Surfactants
Because of their polar / non-polar structure,
such molecules will associate with a phase
interface such as the air-water interface of an
air bubble, these are called surfactants.
air bubble surface
non-polar tail
air water
polar head () and (-) charge
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Adsorption Microflocculation
When surfactants in water come in contact with
the surface with an air bubble, they orient
themselves along the bubble surface. When
enough bubbles carrying enough surfactants collect
, they begin to condense into foam
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Foam Formation
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Foam Fractionation or Protein Skimming
LSS components that favors the natural processes
of adsorption and accumulation of DOM
which otherwise cannot be mechanically filtered.
FF come in a variety of designs to collect
and condense DOM, and remove them from the water
column.
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Disinfection By Means of Removal

• During the collection and condensing of DOM,
  other
• small particulates will get caught up in the
  formation of
• sticky foam and will be carried out of the water
  column
• This process includes capturing of coliform
  bacteria or
• any other microorganism that is small enough for
  capture
• Thus, disinfection is achieved via removal rather
  than
• the actual destruction or disruption of the
  organism

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Disinfection Via Removal
Graph showing decreased oxidant demand in an
outdoor Seal Pool after retrofit of FF outfitted
with flocculation dose ozone injection (December
- May, 1994 and 1995, NAIB) Source McCracken,
RAW, 1995 Albuquerque NM
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Ozones Role in FF





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• Small organic and inorganic particles of like
  electrostatic charge will repel each other and
  thus be held in suspension in the water column,
  creating a haze and adding to DOM.
• By applying a VERY SMALL dose of ozone, the
  charge of SOME of the particles can be changed,
  bringing about their destabilization.

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Disinfection Ozone Dose in FF

• When a higher (disinfection) dose of ozone is
  used in a Foam Fractionator
• The charges of all suspended particles are
  altered and the benefit of microflocculation is
  lost
• Ozone begins to break apart the carbon bonds of
  the long-chain molecules that are adhering to
  bubble surfaces, pieces go back into solution
• Ozone gas is likely to leak into the pump room
• For these reasons, it is very important to dose
  ozone
• very lightly in FF 0.01 - 0.03 mg O3/L

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Disinfection Via Removal
Coliform counts in a Manatee exhibit (June 99
through June 2000, Columbus Zoo) no ozone contact
chamber, only disinfection unit is foam
fractionator. Source Aiken, IAC, Monaco, 2000
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Ozones Role in FF
Using ozone as a flocculant is best achieved
using an ORP controller designed for Foam
Fractionation
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Placement within LSS

• FF works best with independent feed and return
  lines,
• manifolding will cause hydraulic effect between
  fracs
• Fracs should not be set up to run off existing
  pressure of
• other components whose pressure may vary (sand
  filter)
• FF works best with dirty water - placing it first
  in the
• LSS sequence is most effective
• Placing FF first also reduces the workload of
  other
• components which can then be reduced in size or
  number

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Reduced Need for Other Components Can Make Space
for FF
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1. Cut a Big Old Hole in the Wall
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2. Out With the Old
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3. Make Room for the New
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4. Retrofit With Foam Fractionators
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Retrofit With Foam Fractionators
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5. Add De-Aerating Biofilter
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Summary Effects Benefits of FF

• FF removes DOM that cannot be mechanically
  filtered
• FF also disinfects by removing infectious
  contaminants
• Suspended particles can also be flocculated and
  removed
• w/ small doses of ozone

? Oxidant Demand ? Nitrogen species ?
Requirement for Buffer ? Size / Number of other
components
? pH ? O.R.P. ? Dissolved Oxygen ? Water Clarity