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Nalco Global Municipal Services offers
a wide range of programs and key technologies:
Clarification
Polymers replace or reduce the inorganic
chemicals used in raw water clarification. By
replacing inorganic chemicals, polymers will:
- increase the stability
of the water by not depressing the pH
- decrease sludge handling
cost by not adding additional solids
- decrease soluble metals
in the effluent
- reduce the need for feed
systems to handle large volumes
Laboratory jar testing can
establish the quantity of inorganic products that
can be replaced and the overall cost savings to
be expected with the optimum polymer dosage.
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Reverse
Osmosis
Membrane systems
have been widely adopted in the industrialized
and developing world as an efficient and cost-effective
technology for the production of quality municipal
and industrial grade water. Membrane process technology
is also becoming more frequently selected for
use in wastewater treatment applications.
Our PermaCare® Membrane Separations
Group provides world-class programs that enhance
the performance of membrane systems and minimize
operating costs.
Contact your local Nalco office for the name of a distributor near you or visit the PermaCare® section of our Web site.
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Sludge
Dewatering
Municipal wastewater
facilities have used various methods to dewater
sludges removed in the treatment process. Some
of these methods are drying beds, vacuum filters,
centrifuges, belt filter presses, pressure filter
presses, and others to concentrate the solids
prior to land applications, landfill, or incineration.
Polymers are used to improve the operations by
improving solids capture and increasing cake solids.
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Sludge
Thickeners
Properly managed
thickening operations provide maximum concentration
of municipal sludges. Thickening with polymers
concentrates suspended solids by flocculation
and improves the capture in all thickening equipment
such as gravity thickeners or air floatation units.
Enhanced solids thickening increases downstream
equipment efficiency.
Laboratory jar testing can
establish the correct product and dosage which
will optimize performance to achieve the highest
solids concentration and greatest solids capture.
Settling Aids
Polymers can improve
the settling rate of flocculated solids in both
conventional settling basins and upflow solids
clarifiers.
During high temperature periods or when throughput
rates change, operational difficulties occur and
floc carryover takes place. Polymers offer several
benefit
- increasing the concentration
of solids in the sludge blanket
- increasing the settling
rate of solids
- reducing sensitivity to
temperature & flow fluctuations
Laboratory jar test
can establish the dosage required to improve settling
and reduce solids carryover.
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Corrosion
Inhibitors
Corrosion products
from the distribution system cause aesthetic problems
due to red water (iron) or blue water (copper)
staining.They can also cause health problems due
to lead or asbestos fibers releasing into the
water supplied to the homeowner. To prevent these
problems along with operational problems due to
accumulation of corrosion products or tuberculation
buildup on the walls of the pipe, corrosion must
be controlled.
An analysis of the water quality,
system metallurgy, and treatment objectives will
identify the most cost effective chemistry to
control corrosion.
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Pb/Cu
Corrosion Inhibitors
The Safe Drinking
Water Act (SDWA) passed by congress in 1974 required
the U.S. Environmental Protection Agency (EPA)
to protect public health by setting drinking water
standards for public health supplies. Lead and
copper maximum contaminant levels (mcl's) were
established and became effective June 19, 1988.
The major source of lead and/or copper in drinking
water is a result of the corrosive action of the
water on the materials in the distribution system
and not from the source water per se.
An analysis of the water quality,
system metallurgy, and treatment objectives will
identify the most cost effective treatment chemistry
to control corrosion. Nalco will supply
products that solve this problem without adversely
affecting another aspect of the treatment process.
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Scale
Inhibitors
Scale contributes
to decreased efficiency of the entire distribution
system. It reduces pipe diameter resulting in
increased energy cost to pump the same water flow
through the pipe. In addition, the scale acts
as sites for biological activity and possible
corrosion attack under the deposit.
Since the late 1950's
Nalco has been treating municipalities with polyphosphate
to prevent scale. As a result of continued research,
zinc polyphosphate glass was found to be 2 to
4 times as effective. The small amount of zinc
prevents the reversion of polyphosphate to orthophosphate
which will not prevent scale. Polyphosphate alters
the crystalline structure of the scale and is
well known by the term, threshold scale inhibitor.
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Fe/Mn
Stabilizers
In order to prevent
'red water' and 'black water' complaints common
to many municipal distribution systems served
by ground water supplies, it is necessary to stabilize
iron and manganese at the raw water source. Soluble
iron and/or manganese when chlorinated or exposed
to the atmosphere will oxidize rapidly. The resulting
hydrated metal oxides can cause staining, plugging
of small passages, under-deposit corrosion, and
increased fouling and flow resistance.
Polyphosphates stabilize these
metal oxides in the colloidal state so they remain
indiscernible and can not precipitate. Zinc polyphosphates
prevent the reversion of polyphosphate to the
orthophosphate form which will not stabilize the
iron.
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Filter
Aids
Filter backwashing
allows turbidity and floc carryover to pass through
the filter before a mat can be established or
in-depth conditioning of the filter media can
occur. Polymers prevent turbidity breakthrough
and extends the filter run to full headloss. The
polymer conditions the filter media to remove
flocced particles resulting in:
- reduces filter to wastewater
after backwash
- longer filter life due
to fewer backwashes
- higher quality effluent
- captures treatment errors
in upstream equipment
Laboratory filter index
testing can establish the optimum polymer dosage
to begin treatment.
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Zebra
Mussel Control
Introducing VeliGON® Zebra Mussel Control.
Simply feed the appropriate VeliGON molluscicide
during zebra mussel spawning periods, then relax!
No more zebra mussel problems! Ever!!
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