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 Phase
IV Land Disposal Restrictions (article)
The final Phase IV Land Disposal Restrictions (LDR) went into
effect on August 24, 1998. Two primary provisions of the rule
will impact foundries across the country. In most cases, these
provisions will translate into increased treatment costs and,
for some, the need to completely redesign their waste management
process.
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Evaluation
Methods for Chemical Based Stabilization Process
Abstract : Cement based Processes have been the most common
solidification/stabilization (S/S) processes for metal immobilization
used in industrial sludge treatment or land reclamation projects.
These processes may rely on a silica gel, free hydroxide and
cement structure to immobilize soluble metals. As the mining
industry finds certain mineral forms to present special challenges
in extraction, the waste management industry can benefit from
incorporating target contaminants into similar waste forms. Chemical
based stabilization processes, without cement addition, have
been utilized to immobilize metals by precipitation, sorption,
or altering the chemical nature of the waste. These stabilization
processes include the use of phosphates, carbonates, sulfides,
and iron rich clays.
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New Process
For Stabilizing Lead-Based Paint
Abstract : An entirely new process for treating lead-based
paint on bridges and other structures is now available to render
the paint and blasting residue non-TCLP (Toxicity Characteristic
Leaching Procedure) hazardous. This process combines a proven
lead stabilization chemistry and a unique process of over coating
the old paint to stabilize the lead immediately prior to paint
removal.
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Lead
Paint Neutralized (article)
Case Study on
the use of Enviro-Prep®
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Lead
Orthophosphates - IV Formation and Stability in the Environment
Abstract : Experimental
and predicted thermochemical constants are used to assess the
formation and stability of lead phosphates in soil and sedimentary
environments. For the chemical conditions likely to be encountered
in oxidizing environments, the stability fields of pyromorphites
[Pb5 (PO4)3X, X=OH-,
Cl-, Br- and F-] and plumbogummite
[PbAl3(PO4)2(OH)5.H2O]
predominate strongly over those of the other secondary lead
minerals. The theoretical phase relationships together with
several field observations are used as the basis for suggesting
that the interaction of lead and phosphorus (to form pyromorphites
and plumbogummite in particular) is an important buffer mechanism
controlling the migration and fixation of lead in the environment.
Calculations using the concentrations of lead and phosphate
ions in serum indicate that the solubility of lead phosphates
ma be the limiting factor with regard to lead ion concentration
in human body. The removal of lead from wastewater by precipitation
as lead chloropyomorphite is considered a spin-off of possible
industrial interest. <
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In
Situ Formation of Lead Phosphates in Soils as a Method to Immobilize
Lead
Abstract : Considerable
evidence, both theoretical and experimental, supports the assertion
that lead phosphates are the most stable environmental soil
lead form and that they may form rapidly when adequate phosphate
is present. This study demonstrated that the weathering of
of galena to insoluble lead phosphates in soils at a port facility
historically used for shipment of ore concentrates is due to
the presence of adequate soil phosphate. Geochemical modeling
indicated that the addition of a phosphate amendment to Pb-bearing
soil would result in lead phosphate formation with an estimated
aqueous lead solubility of 0.1 micrograms/L in soil. Assessment
of the potential lead bioavailability from ingestion of pyromorphite,
which will be controlled by lead mineral dissolution in the
acidic environment of the human stomach, indicated limited
bioaccessibility of lead. The study results suggest that in
situ lead stabilization through phosphate amendment may provide
a cost-effective method for reducing the leaching, migration
and bioavailability of lead from soils.
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TCLP
Testing
Abstract : The
TCLP is used to quantify the extractability of certain hazardous
constituents from solid waste under a defined set of laboratory
conditions. This test is used to evaluate the leaching of TC
metals, volatile and semivolatile organic compounds, and pesticides
from wastes. In principle, this procedure simulates the leaching
of constituents into groundwater under conditions found in
a municipal solid waste (MSW) landfill. The TCLP, however,
does not simulate the release of contaminants to non-groundwater
pathways. The TCLP is most commonly used by EPA and state agencies
to evaluate the leaching potential of wastes, and for determining
toxicity.
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Effects
of Freezing on Enviro-Prep® (article)
Study of the
effect of multiple freezes of Enviro-Prep® .
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a copy of the whole article, Please fill out our form.)
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