Aluminum applications pose significant risk to biota and possibly to
human consumers of the water if the
of treated water falls below
6.0 and
dissolved aluminum
appears.
The dose determination technique is
designed to prevent this occurrence.
This mate-
Fly ash has also been suggested as a phosphorus inactivant.
rial will produce significant adverse environmental impacts and should not be
added to reservoirs.
Table 3 is a summary of this method.
Table 3
Summary of Phosphorus Inactivation
Characteristic
Description
Targets
Nuisance algal blooms,
transparency, release of
phosphorus from sediments.
Mode of action
Phosphorus release from reservoir sediments is sharply
reduced, producing lowered phosphorus concentrations
in water column.
Effectiveness
Highly effective, problem eliminated when accompanied
by significant diversion of external nutrient
loading.
Longevity
Up to 12 years; few long-term evaluations available.
Negative features
Use of aluminum sulfate will lower
Overdose could produce appearance of toxic dissolved
aluminum.
may contain a high density of bacteria,
The
including pathogens.
Application is labor intensive.
Labor and chemical costs will be high but can be
determined if dose is known (see text for equations).
Applicability to
No published record of use in reservoirs with large
reservoirs
areas.
New methods of application may have to be developed to
lower costs.
Treatment of high phosphorus-release areas should be
attempted.
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