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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.
APPENDIX E
BENCH-SCALE
FEASIBILITY TESTING PROJECT
SCOPE OF WORK
2/10/97
MWRA/MASCO
Hospital Mercury Work Group
End-of-Pipe Subcommittee, Technology Identification Subgroup
Objectives
The
Technology Identification Subgroup (the Subgroup) has
established a project goal of bench-scale testing of promising
treatment technologies for Mercury removal from wastewater.
The testing is to be performed by Suppliers of the
technologies using a sample of hospital clinical laboratory
wastewater. The testing is to include "systems"
considerations for handling of interfering wastewater
constituents and for optimization of the Mercury removal
process relative to an effluent concentration goal in the
order of 1 microgram per liter (µg/L). In the test report,
the Supplier shall include discussion of the Mercury removal
process relative to the need for (or advantages of) raw
wastewater equalization, pH control, and biological
sterilization and for final treated effluent neutralization.
The discussion shall consider the allowed effluent pH range to
be 5.5 to 10.5 Standard Units. The Supplier shall perform
sufficient bench-scale testing to allow preliminary estimation
of full-scale (24 hours/day) system capital and operating
costs for wastewater flows of 2,000 gallons per day (GPD),
20,000 GPD, and 50,000 GPD. The Supplier shall detail the cost
estimates in the overall test report and shall explain any
omissions from or limitations in the estimates. The Supplier
shall also estimate full-scale system space requirements (L x
W x H) for each of the three flows along with a typical
equipment layout diagram.
Attachment
2 provides information that you may want to consider prior
to performing the feasibility testing.
Shipment
of Raw Wastewater Sample from the Subgroup to Supplier
The
raw wastewater sample (quantity to be determined) will be
collected by the Subgroup from an existing collection tank and
will be shipped to the Supplier via overnight express. At the
time of collection, an aliquot of the sample will be taken and
analyzed for total and dissolved Priority Pollutant Metals
(antimony, arsenic, beryllium, cadmium, chromium, copper,
lead, mercury, nickel, selenium, silver, thallium, and zinc)
by the Subgroup. The analytical laboratory report will be
faxed to the Supplier as near to the sample delivery time as
possible. The sample is expected to have a Mercury
concentration between 20 and 40 µg/L. Other chemical
parameters shall be assumed to be similar to the results of a
comprehensive characterization study that was previously
performed by the Subgroup on a sample of the wastewater. The
Supplier shall use proper equipment and sample handling
procedures for personnel protection and safety when handling
clinical laboratory wastewater. For scheduling purposes, the
Subgroup will begin collection and shipment of the wastewater
sample on or near February 24, 1997.
Quality
Control
Verification
of Proper Sampling and Analysis Techniques
(Note:
The Subgroup acknowledges that the following quality control
procedures may be cumbersome to the Supplier. If you have a QC
program that is comparable to the one described below, please
submit a description
of the program for review by the Subgroup.)
Within
five days after the Supplier has received the raw wastewater
sample and empty sample bottles, the Supplier
shall prepare for analysis:
-
10
high purity deionized water samples (500 ml sample volume
required) prepared in the Supplier’s laboratory using the
Supplier’s own high purity water supply and its own
prepared sample bottles.
-
10
additional samples of the Supplier’s high purity deionized
water collected in the sample bottles that the Subgroup
supplies.
The
Supplier shall send 5 of each type of sample to the Subgroup for
analysis. The remaining ten samples shall be analyzed by the
Supplier’s lab. Please fax these results to: Karen Rondeau,
MWRA, at (617) 241-2301.
Procedural
Blanks
A
minimum of three procedural blanks (high purity water carried
through the same sample handling procedure and processes as the
samples) from each experimental run shall be performed.
Sample
Handling and Analysis
-
The
Supplier shall collect and analyze as many samples during
testing as he/she deems necessary for determination and
optimization of each element of system performance. At a
minimum, the Supplier shall provide mercury data for each
treatment step and final treated effluent for each test run.
Please see Attachment 1,
Guidelines for Sample Collection and Processing.
-
The
Supplier shall indelibly and clearly mark each sample bottle
label for identification of contents, test run, treatment
step, date, and qualifying comments. These requirements
apply to test samples intended for local analysis and, as
outlined below, to test samples to be returned to the
Subgroup.
-
The
Supplier shall perform on-site preservation of test samples
by addition of concentrated nitric acid to reduce sample pH
to less than 2.0 standard units.
-
The
Supplier shall perform EPA method 245.1 for total Mercury
analyses with equipment and personnel capable of achieving a
method detection limit of 0.2 µg/L.
-
In
an overall test report, the Supplier shall include copies of
all executed "chain-of-custody" sheets and
analytical laboratory test reports. Each laboratory test
report shall clearly identify sample contents, test run,
treatment step, date, and qualifying comments. In addition,
careful documentation and reporting of the result of sample
preparation and analyses, including those of individual
replicates and blank samples should be provided.
Samples
to be sent back
to the Subgroup
Along
with the raw wastewater sample, the Subgroup will ship empty
analytical laboratory sample bottles and
"chain-of-custody" sheets. The Supplier shall submit
to the Subgroup, the following samples for analysis:
-
5
high purity deionized water samples (500 ml sample volume
required) prepared in the Supplier’s laboratory using
the Supplier’s own high purity water supply and its own
prepared sample bottles.
-
5
additional samples of the Supplier’s high purity
deionized water collected in the sample bottles that the
Subgroup supplies.
-
1
procedural blank from each test run.
-
A
split sample of final treated effluent from
each test run. A split sample is a subsample of the same
sample that the Supplier analyzes.
Subgroup
sample bottles intended for metals analyses will be so labeled
by the Subgroup and will be inoculated with nitric acid prior
to shipment. The Supplier shall check pH after filling and
shaking the sample bottle and, if needed, shall add
concentrated nitric acid to assure that the contained sample
pH is less than 2.0 Standard Units for preservation until
subsequent laboratory analyses by the Subgroup. The Supplier
shall be responsible for ensuring that its testing staff
exercises proper and safe handling of the sample bottles and
nitric acid.
All
filled Subgroup sample bottles shall be stored at 4oC
maximum by the Supplier until shipment by overnight express
(paid for by the Supplier) to the Massachusetts Water
Resources Authority Central Laboratory. The deionized water
samples shall be shipped back to the Central Laboratory in the
cooler originally used for wastewater sample shipment. The
Supplier shall refill the cooler with ice before shipment and
shall pack the cooler to minimize the likelihood of sample
bottle damage during shipment. The shipment shall be clearly
labeled with "Project Code HGTECH" and shall
be made to the following address:
Ms.
Polina Eppelman
Massachusetts Water Resources Authority
Central Laboratory
Deer Island
Boston, MA 02152
Project Code: HGTECH
Feasibility
Test Report
The
Supplier shall issue the test report approximately four weeks
after the conclusion of testing (i.e., around the end of
March 1997). If possible, the following test report format shall
be used:
-
Introduction/Background
-
Test
Materials, Procedures, and Experimental Protocol
-
Pretreatment
Considerations
-
Test
Results
-
Full
Scale System Considerations (Cost Estimates, Siting, etc.)
-
Discussion/Conclusions
-
.
Appendices (including analytical test reports)
In the
test report, the Supplier shall include descriptions of:
-
system
process steps,
-
preferred
Mercury speciation,
-
inactivation
of complexing agents that could limit Mercury removal,
-
test
Mercury removals through each process step, and
-
full-scale
system operation and control considerations.
In the
test report, the Supplier shall include discussion of the
Mercury removal process relative to the need for (or advantages
of) raw wastewater equalization, pH control, and biological
sterilization and for final treated effluent neutralization. The
discussion shall consider the allowed effluent pH range to be
5.5 to 10.5 Standard Units. The discussion shall also consider
the rather large daily and hourly variabilities that, depending
upon the clinical laboratory facility, could occur in the
wastewater flow, pH, mercury concentration, and the presence and
concentration of potentially interfering and mercury-complexing
chemicals.
Contact
Person for Public Document
Since
the Subgroup is associated with the Massachusetts Water
Resources Authority, an agency of the Commonwealth of
Massachusetts, the test report will become part of a public
document. Accordingly, the Supplier is invited to include name(s)
of a contact person or persons with mailing addresses and
telephone/fax numbers for future inquiries by other parties.
Recommended
Guidelines for Sample Handling and Processing
Because
the mercury content of samples, especially after pretreatment,
may be close to or less than that detectable by EPA method
245.1, contamination during the collection and processing of
samples may severely compromise the integrity of the analysis
and subsequent interpretation of results of any experiments
conducted. Contamination and analytical problems in analysis of
trace concentrations of mercury are well known and provide
significant challenges for most laboratories. The following are
recommendations to minimize these potential problems:
-
Use
extreme care in the collection and processing of samples.
Typically the collection of several hundred mls for analysis
is required, more if replicate analysis is to be conducted
or sample splits prepared. Contamination from dust and
residual vapor phase mercury, improper handling (plastic
gloves should be used at all times), improperly cleaned
labware and cross-contamination from samples with very high
mercury concentrations are especially prevalent sources of
error.
-
Labware
in contact with samples should be cleaned by use of a common
laboratory detergent and then acid-cleaned either in hot
concentrated nitric acid or by soaking in 6M HNO3 overnight
followed by thorough rinsing with high purity deionized
water.
-
The
use of Teflon or glass labware is preferred to minimize
sorption losses. Sample containers (glass stoppered 500 ml
Erlenmeyer flasks or 500 ml Teflon bottles are useful)
should be stored in plastic bags after cleaning and after
filling with sample to minimize the possibility of
contamination. If possible, do not use sample bottles
previously containing samples with high concentrations of
mercury to collect samples you anticipate will have mercury
at much lower levels (e.g. after treatment). After cleaning
and in between use, store sample bottles filled with 10%
HNO3 prepared using high purity deionized water.
-
Because
many laboratories have difficulty in producing high quality
results at 1 ug/l or lower, you may wish to pre-evaluate the
capabilities of the laboratory ( and your ability to prepare
clean sample bottles) by sending the lab you plan to use
approximately five samples of your high purity water. If the
results are erratic, you will need to evaluate whether the
lab or your sampling technique is the source of error.
Inability to consistently achieve mercury concentrations
less than the detection limit in high purity deionized water
samples should be of concern and perhaps require the use of
another laboratory.
Additional
Information Concerning Pretreatment Considerations
The
Subgroup has obtained information regarding the field testing of
an innovative mercury removal technology that is being conducted
through the assistance of the Massachusetts Strategic
Envirotechnology Partnership (STEP) program. The testing of this
system has been underway for about four months. While this
testing was conducted on scrubber wastewater from a medical
waste incinerator, rather than clinical laboratory wastewater,
it has yielded information which we feel would be useful to the
Supplier in the performance of this feasibility testing:
-
Mercury
speciation studies revealed that the forms in which mercury
may be found are both complex and variable. The results
showed that a significant amount of the mercury in the
wastewater are bound to colloids and particulates in
suspension (as much as 64% in one sample), or exists in the
form of organic complexes.
-
Based
on these speciation results, a number of pretreatment
techniques were evaluated to either remove the non-binding
forms of mercury or to release the bound mercury to allow
the removal system to recover it: chlorination, using
hypochlorite; ultrafiltration; activated carbon; and
reducing the pH of the wastewater. The use of hypochlorite
was found to be the best approach, resulting in significant
improvement in the performance of the system. The system was
consistently able to remove >99.5% of the mercury (at
feed levels of 500 to 10,000 ppb) to discharge levels of
under 5 ppb when hypochlorite was used. The optimal
pretreatment was to add sufficient hypochlorite to reach a
level of 1 - 5 mg/L residual chlorine with a 15 - 30 minute
reaction time.
-
The
initial work with hypochlorite used an ORP electrode to
measure the residual chlorine level. This approach, however,
was found to be somewhat inexact and time consuming, and was
replaced with a wet chemical method using the DPD
colorimetric test.
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