Reductions of Silicates and Fluoride in Water and Wastewater
Silica:
Both collodial and soluble silica are naturally occurring in virtually all
water types. Normally, silica is found as a composite - and referred to as
"silicate", as the silica forms a crystalline structure around one or more
other elements. Thus silicates can contain virtually any metal or mineral
inside it's structure. Additionally, where wastewater is involved, the silica
can be bonded quite tightly to various chemicals or elements such as
ammonia or nitrogen.
Because silicates are crystalline structures, they are extremely
damaging to Reverse Osmosis membranes, and due to their flat/plate
like physical structure, create major clogging issues. This creates a large
reject volume and major operational costs for those processes and
applications where reverse osmosis or Ultrafine filtration is utilized.
Through various tests, electrolytic oxidation has proven that silicate
structures can be "fractured", basically broken apart, and the bonded
metal, mineral or chemical component oxidized. This oxidation creates a
heavier then water precipitate or sludge. Additionally, due to the
polarization effect of the electrolytic field created by the process, the
oxidized compounds take on either a positive or negative charge,
attracting them to other precipitates. This electromagnetic attraction
creates very rapidly, large precipitates in the water, that are easier and
less expensive to capture and remove using medium to course filtration
techniques - such as diatomaceous earth, slow sand, bag, mixed media,
or fine screen filter systems.
The level of silicates in the water is immaterial, at least tests ranging from
over 3,000 mg/l to as low as 0.01 mg/l have not found where the level
determines the rate or level of reduction. Additionally, different then R/O
and mixed media, no adjustment of the water's pH must occur prior to
treatment.
Fluoride:
Soluble fluoride and composites containing fluoride that require removal
from a water source, require the same level of electrolytic treatment.
Primarily, this means that a set minimum level of DC current must be
applied to the water to get the fluoride to "break" any existing bonds,
and take on a polarity. Tests have shown that fluoride will take on a
"positive" charge, and bond to other elements in the water, creating
heavier then water precipitates, much as silica (and mercury) does. The
micron size of the precipitate is determined but what other elements are
in the water, but tests showing where fluoride is the predominate
element present, have shown that micron filtration levels for capture of
the precipitate range from 3 to 1-micron nominal. Additionally,
diatomaceous earth works well to remove the fluoride precipitate, owing
to the interaction of the differing polarities.
Operational Cost Issues:
Tests have shown that operational life of R/O membranes can be
increased 3x by pretreatment of the water by the electrolytic oxidation
process (EOH2O). For one customer, this meant a savings of over
$90,000 every 3-months, as well as the discontinuation of the secondary
distillation process following R/O treatment. The estimated increase in
"usable" water was 75% - with the corresponding reduction of reject
water. This was not only a major operational cost savings, but a good
public relations move - as the factory was located in a state with a
continuing freshwater supply shortage.
The main operational cost involved with use of the electrolytic process
is electricity. The power requirements for each 1-phase 220-240v
electrode power controller for the above applications is 6kWh. Where
3-phase electrical power is available, this reduces to 4kWh.
Electrodes also require replacement. But this normally every 2-3 years -
and can be much longer where freshwater is the water source under
treatment, as opposed to a highly acidic/high chloride containing
wastewater.
Example: Precipitate formed with electrolytic oxidation of brackish
geothermal well water. This was for fluoride, silica, and phosphate
reductions. Initial levels exceeded 3,000 mg/l of silica; 6,000 mg/l of
fluoride, and 200 mg/l of phosphate. Photo shows both level of
precipitate in 500ml bottle (approximately 1.25" in 7") and stability - as
the precipitate was formed over 27-months ago.
Silica:
Both collodial and soluble silica are naturally occurring in virtually all
water types. Normally, silica is found as a composite - and referred to as
"silicate", as the silica forms a crystalline structure around one or more
other elements. Thus silicates can contain virtually any metal or mineral
inside it's structure. Additionally, where wastewater is involved, the silica
can be bonded quite tightly to various chemicals or elements such as
ammonia or nitrogen.
Because silicates are crystalline structures, they are extremely
damaging to Reverse Osmosis membranes, and due to their flat/plate
like physical structure, create major clogging issues. This creates a large
reject volume and major operational costs for those processes and
applications where reverse osmosis or Ultrafine filtration is utilized.
Through various tests, electrolytic oxidation has proven that silicate
structures can be "fractured", basically broken apart, and the bonded
metal, mineral or chemical component oxidized. This oxidation creates a
heavier then water precipitate or sludge. Additionally, due to the
polarization effect of the electrolytic field created by the process, the
oxidized compounds take on either a positive or negative charge,
attracting them to other precipitates. This electromagnetic attraction
creates very rapidly, large precipitates in the water, that are easier and
less expensive to capture and remove using medium to course filtration
techniques - such as diatomaceous earth, slow sand, bag, mixed media,
or fine screen filter systems.
The level of silicates in the water is immaterial, at least tests ranging from
over 3,000 mg/l to as low as 0.01 mg/l have not found where the level
determines the rate or level of reduction. Additionally, different then R/O
and mixed media, no adjustment of the water's pH must occur prior to
treatment.
Fluoride:
Soluble fluoride and composites containing fluoride that require removal
from a water source, require the same level of electrolytic treatment.
Primarily, this means that a set minimum level of DC current must be
applied to the water to get the fluoride to "break" any existing bonds,
and take on a polarity. Tests have shown that fluoride will take on a
"positive" charge, and bond to other elements in the water, creating
heavier then water precipitates, much as silica (and mercury) does. The
micron size of the precipitate is determined but what other elements are
in the water, but tests showing where fluoride is the predominate
element present, have shown that micron filtration levels for capture of
the precipitate range from 3 to 1-micron nominal. Additionally,
diatomaceous earth works well to remove the fluoride precipitate, owing
to the interaction of the differing polarities.
Operational Cost Issues:
Tests have shown that operational life of R/O membranes can be
increased 3x by pretreatment of the water by the electrolytic oxidation
process (EOH2O). For one customer, this meant a savings of over
$90,000 every 3-months, as well as the discontinuation of the secondary
distillation process following R/O treatment. The estimated increase in
"usable" water was 75% - with the corresponding reduction of reject
water. This was not only a major operational cost savings, but a good
public relations move - as the factory was located in a state with a
continuing freshwater supply shortage.
The main operational cost involved with use of the electrolytic process
is electricity. The power requirements for each 1-phase 220-240v
electrode power controller for the above applications is 6kWh. Where
3-phase electrical power is available, this reduces to 4kWh.
Electrodes also require replacement. But this normally every 2-3 years -
and can be much longer where freshwater is the water source under
treatment, as opposed to a highly acidic/high chloride containing
wastewater.
Example: Precipitate formed with electrolytic oxidation of brackish
geothermal well water. This was for fluoride, silica, and phosphate
reductions. Initial levels exceeded 3,000 mg/l of silica; 6,000 mg/l of
fluoride, and 200 mg/l of phosphate. Photo shows both level of
precipitate in 500ml bottle (approximately 1.25" in 7") and stability - as
the precipitate was formed over 27-months ago.
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