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Mercury
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Tech. Identification
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For more
information, contact David Eppstein by email at
deppstein@masco.harvard.edu,
or by calling 617-632-2860.
EXECUTIVE SUMMARY
This
Report is a product of the Technology Identification Subgroup of
the Phase II MWRA/MASCO Mercury Work Group, End-of-Pipe
Subcommittee. It presents the results of bench-scale feasibility
tests of six mercury pretreatment technologies on samples of a
clinical laboratory wastewater. This Report can be used as a
resource by facilities that are investigating mercury removal
technologies.
The
Technology Identification Subgroup was established to determine
if there are technologies available that could remove mercury
from wastewater to very low microgram per liter (µg/L) or part
per billion (ppb) concentrations. In 1995, the conclusions of
the Mercury Work Group in Phase I were that no technologies were
available to remove mercury to such low concentrations and that
no cost-effective removal technologies were foreseen. For
purposes of this new study, the Subgroup decided that
bench-scale feasibility tests of several promising mercury
removal technologies should be performed to address the need for
up-to-date information. For each technology, test effluent
mercury concentrations would be measured against a goal of 1.0
µg/L (ppb). In addition, the Subgroup decided to investigate
the probable costs and spatial requirements of currently
available mercury removal systems.
To
better understand the characteristics of various medical
wastestreams that often contain mercury, another subgroup (the
Wastewater Characterization Subgroup) performed a hospital
wastewater characterization study. This study was used by the
Technology Identification Subgroup to determine what type of
wastestream would be most appropriate for the feasibility
testing project. The data from the characterization study was
also used by the participating vendors identified below to
determine what treatment steps, if any, might be needed prior to
their mercury removal technologies.
The
Technology Identification Subgroup decided to focus its
Bench-Scale Feasibility Testing Project on a local hospital’s
clinical laboratory wastewater stream because such wastestreams
have posed difficult compliance issues for hospitals. The
selected hospital offered an accessible and consistent, but
complex, wastewater stream containing organic solvents,
phosphates, suspended solids, various heavy metals, and mercury
at concentrations ranging from 11 to 90 µg/L (ppb).
The
Technology Identification Subgroup initially performed a
literature and Internet search and identified twelve vendors of
potentially applicable metals removal technologies. Of these
twelve vendors, six vendors elected to participate in the
Bench-scale Feasibility Testing Project. The participating
vendors were:
-
Aero-Terra-Aqua
(ATA) Technologies Corporation
-
Barnebey
& Sutcliffe Corporation
-
ICET,
Inc.
-
KDF
Fluid Treatment, Inc.
-
Soils
N.V.
-
SolmeteX,
Inc.
Each
participating vendor was asked to determine all necessary pre-
and post- treatment steps needed for effective removal of
mercury from the clinical laboratory wastewater and to consider
overall compliance of the pretreated effluent with MWRA sewer
discharge regulations. Each vendor was also asked to identify
all potentially interfering metals/compounds, suggest an
appropriate scheme of unit operations, provide schematic
diagrams, address full-scale system considerations, and attempt
to estimate preliminary capital and operating costs for 2,000,
20,000, and 50,000 gallon per day full-scale systems.
All six
participating vendors submitted draft reports on their test
work. The Subgroup reviewed all six draft reports for accuracy
and clarity, and issued a list of comments and questions to each
vendor. The Subgroup requested the vendors to consider the
questions and comments and to submit a final revised report by a
specific deadline. One vendor did not submit a final revised
report as requested.
Through
its Bench-scale Feasibility Testing Project, the Subgroup has
found, for samples of one clinical laboratory wastewater stream,
that five different pretreatment technologies showed test
mercury removal efficiencies that ranged from approximately 44
percent to greater than 99.5 percent. The Subgroup found,
therefore, that there are currently available technologies that
show potential to remove mercury to very low µg/L (ppb)
concentrations. For certain test runs, some technologies
achieved the concentration goal of 1.0 µg/L (ppb) mercury on
samples of the clinical laboratory wastewater stream.
Regarding
full-scale pretreatment systems, preliminary estimated costs and
spatial requirements were provided by the vendors of the tested
technologies. The Subgroup found that the estimated costs and
spatial requirements for many of the proposed systems were
comparable to those of classical metal removal systems.
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