New Bedford Harbor's Environmental Problems and Bench-Scale Evaluation of Filter Press Dewatering Process

1. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
1
New Bedford Harbor’s Environmental Problems
and Bench-Scale Evaluation of Filter Press
Dewatering Process
Written by Minh Tran, R&D Intern, Waste Stream Technology, Inc., Buffalo, NY
Field Supervisor: Dr. Brian Schepart
Laboratory Advisor: Nicole O’Sullivan
August 14, 2009

2. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
2
Table of Contents
List of Tables …………………………………………………………………….. 3
I. A Description of New Bedford Harbor and Its Environmental Problems ... 4
II. An Introduction of Cleanup Methods ………………………………………. 5
III. Filter Press Tests
1. Scope of Work …………………………………………………………………………... 6
2. Initial Characterization …………………………………………………………………... 6
3. Filter Press ………………………………………………………………………………. 7
4. Summary and Conclusions ……………………………………………………………… 8
IV. New Bedford Harbor’s Current Status ……………………………………. 9
References ………………………………………………………………………. 11
Appendix A ……………………………………………………………………... 12
Appendix B ……………………………………………………………………... 13
Appendix C ……………………………………………………………………... 14

3. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
3
List of Tables
Table 1. Analytical methods utilized for sample characterization ……... 7
Table 2. Cleanup time frame depends on future funding rates ……….. 10

4. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
4
I. A Description of New Bedford Harbor and Its Environmental Problems
New Bedford Harbor is an urban tidal estuary on Buzzards Bay, in southeastern
Massachusetts. Since the early nineteenth century, New Bedford Harbor has been considered the
leading fishing and whaling port in the United States in terms of annual fish catch. The wealth in
fishing opportunities drew many immigrants and brought prosperity to the city of New Bedford.
In 1991, the population of the city was
estimated to be nearly 100,000 which
represented about 40% of the total
population in the Bay’s drainage basin.
Acushnet River, a 1,000-acre estuary, serves
as the city’s main waterway.1
Until the
1970’s, there were no strict standards
applying to water pollution. As a result, local
businesses including factories, textile mills
and fish processing plants freely dumped
their industrial wastes into the river. From
1940 to 1978, before the use of
polychlorinated biphenyls (PCBs) was
banned by the U.S. Environmental Protection
Agency (EPA), two manufacturers of electrical parts, mainly the Aerovox Corporation,
discharged an enormous volume of PCB-
contained industrial process wastes directly into
the New Bedford Harbor and indirectly through
the city’s sewer system. Alerted by a series of
studies conducted from 1974 to 1982 regarding
high concentrations of PCBs found in
sediments and biota along the Acushnet River
into Buzzards Bay, the EPA added New
Bedford Harbor to its Superfund List in 1983.2
PCBs are chlorinated, colorless, odorless,
semi-volatile organic compounds that have
been classified as carcinogens. For industrial
applications, PCBs were mostly used as
electrical insulators in capacitors and
transformers. Since PCBs are insoluble in
water, they adhere to sediments settling at the
bottom of the waters for a very long period of
time.3
PCBs have spread from the Hot Spot, a
FIGURE 1 New Bedford waterfront, 2001
FIGURE 2 Various concentrations of PCBs in
sediments. The upper arrow indicates the location
of the Aerovox facility. The lower arrow shows the
hurricane barrier

5. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
5
5-acre portion surrounding Aerovox Corporation, to lower parts of the Acushnet River and the
Bay, due to currents produced by tides. It has been estimated that approximately 0.5 pound of
PCBs is transported by tides to the Bay each day. In the late 1980s and early 1990s, research
indicated that PCB concentrations in marine sediments in the estuary varied from a few parts per
million to over 200,000 ppm (the current clean-up level is 10-50 ppm). In addition, PCBs, when
ingested, accumulate in animal’s tissue, which makes seafood at New Bedford too toxic to be
consumed by humans. In 1979, the Massachusetts Department of Public Health restricted fishing
and lobstering over the 18,000-acre New Bedford Harbor and Acushnet River estuary.4
II. An Introduction of Cleanup Methods
In October of 1983, the EPA
started examining different cleanup
plans. A good method should effectively
and economically remove contaminated
sediments as well as reduce the exposure
of the public to the clean-up sites. Three
proposals finally were recommended for
voting:
a) Dredging and on-site
incineration.
b) Removal, solidification and
disposal in an off-site,
federally approved, landfill.
c) Dredging and treatment with
solvent extraction.
The third option had the potential to
reduce the concentrations of PCBs on the
sediments up to 96-99% by using an
appropriate solvent to dissolve PCBs. This
method, however, had been used successfully
on soils but not on sediment, which had a
much greater water content. As a result,
extensive testing and development should be
performed prior to large-scale application at
New Bedford. Six out of nine committee
members voted in favor of the dredging and
incineration. However, public oppositions
and fears that air-borne contamination
including dibenzofurans, several types of
dioxins and remaining PCBs released from
incineration would spread widely over the
FIGURE 3 Cutterhead section dredge – 6”
dredge depth
FIGURE 4 Map of the cleanup process

6. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
6
New Bedford area forced the EPA to alter its practice and dispose of the sediments in either the
on-site Confined Disposal Facility (CDF) or an off-site certified landfill.2
Sevenson Environmental Services, Inc. (SES) was contracted to perform sediment
remediation and in the Spring of 2004, Sevenson started the construction of treatment facilities.
The contaminated sediments at the bottom of the harbor are hydraulic dredged and transported
by booster pumps and through a floating pipeline to the de-sanding facility. At the de-sanding
building, coarse materials are separated from finer, PCB-laden materials by shaker screen and
hydrocyclone units. While the coarse materials are stored in a lined holding cell near the de-
sanding facility, the finer sediments are delivered, by submerged pipeline, to the de-watering
facility. At the de-watering facility, filter presses squeeze water out of the dredged sediments.
The dry sediments or filter cakes are collected and analyzed for contaminants then disposed off
in the CDFs (if less than 50 ppm PCBs) or transported off-site by train to a licensed PCB landfill
(if greater than 50 ppm PCBs). The large volume of filtrate then requires special treatment to
meet the standards established in ambient water quality conditions (AWQC) in the parts per
trillion range before returning to the harbor.5
III. Filter Press Tests
1. Scope of Work
Prior to deploying large scale dewatering of dredged sediments in the field, several pilot
studies have been conducted in the laboratory to determine optimal conditions for applications.
Since July 2001, Waste Stream Technology, Inc. (WST), a wholly-owned subsidiary of SES, has
performed solidification/stabilization treatability studies on different sediment samples collected
from New Bedford Harbor. The next sections of this part will solely present the results obtained
from filter press testing of the sample collected in June 2009 at New Bedford Harbor. Ultimately,
an optimal condition, which includes polymer dosage, filter press time and pressure, will be
concluded.
2. Initial Characterization
A 5-gallon bucket of sediment sample from New Bedford Harbor was sent to WST by SES
and received on June 12, 2009. Prior to initial analyses, the sample was logged in based on its
weight and receiving date. It was also assigned an R&D number for future identification. Upon
opening the bucket, the sample appeared to be thin, black sludge with no odor. The sample also
appeared to be de-sanded and ready for filter press feed. Prior to subsample for initial
characterization, the sample was mixed thoroughly for a few minutes to ensure homogeneity.
Three characteristics that contribute to the initial analyses of any newly received sample include
percent solids, specific gravity and pH. Table 1 lists the methods employed by the treatability
laboratory.

7. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
7
Analysis Method
Percent Solids Standard Method 2540G
Specific Gravity Standard Method 2710F
pH SW 846 Method 9045C
TABLE 1 Analytical methods utilized for sample characterization
Results of the initial analyses are tabulated and presented in Appendix A. The content of
the sample was mostly harbor water which was indicated by only 9.70% solids. The dominance
of water in the sample was also reflected by the specific gravity of 1.04 which was just slightly
above the density of water. The pH measured was 6.62, which was mostly neutral.
3. Filter Press
The dewatering machines that were used at the
treatability laboratory were bench top recessed-chamber
filter presses. These presses function similarly to the plate
and frame filter presses at the New Bedford Harbor
dewatering facility but with a much smaller scale,
therefore, are suitable for bench scale studies. One-liter of
pretreated sediment sample was fed to the filter press
before each run. Time and filtration pressure were
recorded for comparison. After each run, the filter cake
was collected. Its physical characteristics were evaluated
and its percent solids was measured. An excellent filter
cake can be defined as one that has a high solids recovery
and good handling characteristics – more specifically, is
solid and dry, releases easily from the filter cloths and
does not have a sticky consistency. In a similar manner,
the filtrate was also collected for evaluation of its
physical appearance and for determination of its total
suspended solids (TSS). A high quality filtrate is one that
has few suspended solids, no visible oil and requires
minimal additional treatment. Finally, both filtrate and
filter cakes were disposed of in a
designated waste bucket.
The chemicals that were used to
treat sediment samples before
dewatering were an anionic emulsion
polymer, AE 843 and cationic solution
polymers CP 626 and CP 757. These
polymers, when mixed with
sediments, changed their physical and
chemical properties. More specifically,
the added polymers decreased the
FIGURE 5 Bench top recessed-
chamber filter press used at the
treatability laboratory
FIGURE 6 Plate and frame filter press used at the
dewatering facility

8. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
8
surface area of sediments exposed to leaching, coated the sediments or chemically immobilized
PCBs to keep PCBs from migration.6
In previous treatability studies, the addition of the above
polymers always resulted in very good to excellent filter cakes with clear filtrates. Also,
advanced from previous results, only 300 ppm of either CP 626 or CP 757 were added to each
feed and the press time was maintained at 90 minutes per run. The only parameter that varied
was the pressure, which was increasing from 150 PSI to 225 PSI.
There were totally 11 runs representing different filter press conditions. The result of each
run is summarized, tabulated and presented in Appendix B and C. For convenience and
clarification, Appendix B presents results that were grouped based on polymer type. These
results are shown again in Appendix C but in chronological order. Generally, all tests were
successfully performed. Filter cake qualities appeared as good to excellent. Higher cake solids
resulted in clear filtrates as well. When comparing the effectiveness of CP 626 and CP 757 on
the qualities of filter cakes under the same test conditions, CP 757 was clearly better as indicated
by solids greater than 60% with thoroughly hard cakes compared to solids less than 60% with
soft cake tops for CP 626. The addition of AE 843 to CP 626 increased its performance, from
about 57% to about 60% solids, but had no effect on CP 757. The optimum condition for using
the CP 626 and AE 843 mixture was reached when the pressure was at 200 PSI. Increasing the
pressure did not contribute to better cakes but might result in defective outcomes as shown for
filter press #9. However, without this exception, within the pressure range of 150 PSI – 225 PSI,
the increase of pressure was proportional to the percent solids and, therefore, cake qualities. TSS
data of the filtrates were included as part of the results. Nevertheless, these data provided no
valuable information due to their inconsistency. After comparing all results, mostly based on
percent cake solids, a mixture of one-liter sediment sample and 300 ppm CP757, when fed to a
filter press under 225 PSI for 90 minutes, resulted in the best filter cake with the highest percent
solids (62.49%).
4. Summary and Conclusions
For this treatability study, a series of 11 filter press tests were carried out. Based on the
results obtained from previous studies, individual cationic solution polymers CP 626 and CP 757
FIGURES 7 & 8 Filter cake samples obtained at the treatability laboratory

9. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
9
or a mixture of AE 843 and one of the cationic solution polymers were chosen as treating
reagents. A fixed press time was maintained while the pressure was increased for comparison.
After considering all result data, it was concluded that sediment treated with 300 ppm CP 757 at
225 PSI for 90 minutes would provide the best and most economical performance. Furthermore,
SES and WST have determined through extensive field experience that full-scale filter press
units inevitably achieve filter cakes with up to 2-3% higher solids capture than bench-scale units.
IV. New Bedford Harbor’s Current Status
In order to reduce the
concentrations of PCBs at New Bedford
Harbor to safe levels, the EPA
estimated that about 880,000 cubic
yards of sediments should be removed.
This volume is approximately
equivalent to 175 football fields, each
of which is 3 feet thick.5
After the 2008
cleanup season, the EPA has spent over
200 million dollars but only 14% of the
contaminated sediments were removed.
It has been expected that the total cost
would mount up to 750 million dollars
and it may take roughly the next 24
years to complete. There have been
serious concerns about the length of the
project among community members.
One concern is the continuing
exposures to PCBs through water, air
and food chain which negatively affect
the public’s health. In addition, since
the New Bedford Harbor Superfund site
comprises 1,000 acres of land and
17,000 acres in Buzzards Bay, it has
directly slowed down the city’s plan for
comprehensive redevelopment of New
Bedford and other shoreline
communities.7
On April 15, 2009, Massachusetts
governor Deval Patrick announced the receipt of 25 to 35 million dollars from federal stimulus
budget to speed up the cleanup process at New Bedford Harbor. This will double or triple the
2009 annual fund of 15 million dollars for the project. Recently, due to economic concern, some
Massachusetts law makers have wrote a letter to the EPA’s administrator Lisa Jackson to ask her
to allocate $110 million dollars for the harbor cleanup over the next two years.8
Currently, the
FIGURE 9 Fishing closure areas I, II and III.
Such closure negatively affects New Bedford
Harbor’s economy

10. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
10
EPA is still considering other cleanup alternatives to meet its criteria of safe, effective and
economical performance.
Annual funding level (million
dollars)
Years to complete Costs to complete (million
dollars)
80 4 290
30 11 330
20 18 360
15 26 390
TABLE 2 Cleanup time frame depends on future funding rates

11. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
11
References
1. Geographical History of New Bedford Harbor. Buzzards Bay National Estuary Program.
August 1991 <http://www.buzzardsbay.org/ccmpold/ccmp-chap6.pdf>
2. PCBs Contamination & Cleanup Methods. The Evans School of Public Affairs,
University of Washington. 2001
<http://www.muw.edu/hpgp/docs/NewBedfordSfundCase.pdf>
3. PCBs Properties. National Oceanic and Atmospheric Administration
<http://www.gc.noaa.gov/gc-rp/nbhch01.pdf>
4. The Spread of PCBs. Sevenson Environmental Services, Inc.
<http://www.sevenson.com/project-listings/project-
summaries/?tx_ttnews[tt_news]=15&tx_ttnews[backPid]=32&cHash=7b5a925a12>
5. Dredging and Dewatering Method. U.S. Environmental Protection Agency. 8 August
2008
http://yosemite.epa.gov/opa/admpress.nsf/d0cf6618525a9efb85257359003fb69d/a2b2676
0d55032588525749f004437c8!OpenDocument
6. Solidification/Stabilization Use at New Bedford Harbor. U.S. Environmental Protection
Agency. September 2000
<http://www.cement.org/waste/pdfs/EPASSUseinSuperfund.pdf>
7. New Bedford Harbor’s Current Status. Center for Public Environmental Oversight.
September 2006 <http://cpeo.org/pubs/NewBedford.pdf>
8. New Bedford Harbor’s Current Status. The Official Website of the Commonwealth of
Massachusetts. 15 April 2009
<http://www.mass.gov/?pageID=gov3pressrelease&L=1&L0=Home&sid=Agov3&b=pre
ssrelease&f=090415funding_for_New_Bedford_Cleanup&csid=Agov3>

12. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
12
APPENDIX A
Bench-Scale Evaluation of Filter Press Dewatering Process
Initial Characterization

13. New Bedford Harbor E-835
rec'd 6/12/09
Initial Data
Sample ID % Solids
Specific
Gravity
pH Physical Description
RD09028 9.70 1.04 6.62 Thin, black sludge.

14. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
13
APPENDIX B
Bench-Scale Evaluation of Filter Press Dewatering Process
Filter Press Data (chronological)

15. New Bedford Harbor E-835
rec'd 6/12/09
Filter Press Data
Filter
Press #
Sample ID
% Feed
Solids
Additive
and
Dosage
Press Time/
Pressure
Filtrate TSS (ppm)
Release/
Blinding
% Cake
Solids
Comments
1 RD09028 9.70
300ppm
626
90min/ 200
PSI
Clear,
colorless
78
Excellent/ No
apparent
57.81 Good cake, soft top.
2 RD09028 9.70
300ppm
626 +
35ppm 843
90min/ 200
PSI
Clear,
colorless
80
Excellent/ No
apparent
60.12 Very good cake, slight soft top.
3 RD09028 9.70
300ppm
757
90min/ 200
PSI
Clear,
colorless
66
Excellent/ No
apparent
60.59 Very good cake, slight soft top.
4 RD09028 9.70
300ppm
757 +
25ppm 843
90min/ 200
PSI
Clear,
colorless
79
Excellent/ No
apparent
61.52 Excellent cake, hard throughout.
5 RD09028 9.70
300ppm
626
90min/ 150
PSI
Clear,
colorless
95
Excellent/ No
apparent
57.25 Good cake, soft top.
6 RD09028 9.70
300ppm
626 +
35ppm 843
90min/ 150
PSI
Clear,
colorless
104
Excellent/ No
apparent
59.21 Very good cake, slight soft top.
7 RD09028 9.70
300ppm
757
90min/ 150
PSI
Clear,
colorless
119
Excellent/ No
apparent
60.56 Very good cake, slight soft top.
8 RD09028 9.70
300ppm
757 +
25ppm 843
90min/ 150
PSI
Clear,
colorless
109
Excellent/ No
apparent
60.03 Excellent cake, hard throughout.
9 RD09028 9.70
300ppm
626 +
35ppm 843
90miin/ 225
PSI
Clear,
colorless
111
Excellent/ No
apparent
58.92 Very good cake, slight soft top.
10 RD09028 9.70
300ppm
757
90miin/ 225
PSI
Clear,
colorless
98
Excellent/ No
apparent
62.49 Excellent cake, hard throughout.
11 RD09028 9.70
300ppm
757 +
25ppm 843
90miin/ 225
PSI
Clear,
colorless
109
Excellent/ No
apparent
61.74 Excellent cake, hard throughout.

16. New Bedford Harbor’s Environmental Problems & Evaluation of Filter Press Dewatering Process
14
APPENDIX C
Bench-Scale Evaluation of Filter Press Dewatering Process
Filter Press Data (grouped)

17. New Bedford Harbor E-835
rec'd 6/12/09
Filter Press Data
Filter
Press #
Sample ID
% Feed
Solids
Additive
and
Dosage
Press Time/
Pressure
Filtrate TSS (ppm)
Release/
Blinding
% Cake
Solids
Comments
5 RD09028 9.70
300ppm
626
90min/ 150
PSI
Clear,
colorless
95
Excellent/ No
apparent
57.25 Good cake, soft top.
1 RD09028 9.70
300ppm
626
90min/ 200
PSI
Clear,
colorless
78
Excellent/ No
apparent
57.81 Good cake, soft top.
6 RD09028 9.70
300ppm
626 +
35ppm 843
90min/ 150
PSI
Clear,
colorless
104
Excellent/ No
apparent
59.21 Very good cake, slight soft top.
2 RD09028 9.70
300ppm
626 +
35ppm 843
90min/ 200
PSI
Clear,
colorless
80
Excellent/ No
apparent
60.12 Very good cake, slight soft top.
9 RD09028 9.70
300ppm
626 +
35ppm 843
90miin/ 225
PSI
Clear,
colorless
111
Excellent/ No
apparent
58.92 Very good cake, slight soft top.
7 RD09028 9.70
300ppm
757
90min/ 150
PSI
Clear,
colorless
119
Excellent/ No
apparent
60.56 Very good cake, slight soft top.
3 RD09028 9.70
300ppm
757
90min/ 200
PSI
Clear,
colorless
66
Excellent/ No
apparent
60.59 Very good cake, slight soft top.
10 RD09028 9.70
300ppm
757
90miin/ 225
PSI
Clear,
colorless
98
Excellent/ No
apparent
62.49 Excellent cake, hard throughout.
8 RD09028 9.70
300ppm
757 +
25ppm 843
90min/ 150
PSI
Clear,
colorless
109
Excellent/ No
apparent
60.03 Excellent cake, hard throughout.
4 RD09028 9.70
300ppm
757 +
25ppm 843
90min/ 200
PSI
Clear,
colorless
79
Excellent/ No
apparent
61.52 Excellent cake, hard throughout.
11 RD09028 9.70
300ppm
757 +
25ppm 843
90miin/ 225
PSI
Clear,
colorless
109
Excellent/ No
apparent
61.74 Excellent cake, hard throughout.