United States
Environmental Protection
Agency
Research and
Development
(RD681)
IEPA/540/A5-90/007
October 1991
&EPA
E. I. DuPont De Nemours &
Company/Oberlin
Filter Company
Microfiltration Technology
Applications Analysis Report
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SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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EPA/540/A5-90/007
October 1991
DuPont/Oberlin Microfiltration Technology
Applications Analysis Report
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Printed on Recycled Paper
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Notice
The information in this document has been prepared for the U.S. Environmental Protection Agency's (EPA) Superfund
Innovative Technology Evaluation (SITE) program under Contract No. 68-CO-0047. This document has been subjected to
the Agency's peer and administrative reviews and it has been approved for publication as an EPA document. Mention of
trade names or commercial products does not constitute an endorsement or recommendation for use.
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Foreword
The Superfund Innovative Technology Evaluation (SITE) program was authorized in the 1986 Superfund Amend-
ments and Reauthorization Act (SARA). The program is a joint effort between EPA's Office of Research and
Development (ORD) and Office of Solid Waste and Emergency Response (OS WER). The purpose of the program is to
assist the development of hazardous waste treatment technologies necessary to implement new cleanup standards which
require greater reliance on permanent remedies. This is accomplished through technology demonstrations which are
designed to provide engineering and cost data on selected technologies.
This project is a field demonstration under the SITE program and is designed to evaluate the DuPont/Oberlin
microfiltration technology. The technology demonstration took place at a former zinc smelting facility in Palmerton,
Pennsylvania. The demonstration effort was directed to obtain information on the performance and cost of the
technology and to assess its use at this and other uncontrolled hazardous waste sites. Documentation consists of two
reports: (1) a Technology Evaluation Report that describes the field activities and laboratory results; and (2) this
Applications Analysis Report that provides an interpretation of the data and discusses the potential applicability of the
technology.
A limited number of copies of this report will be available at no charge from EPA's Center for Environmental
Research Information, 26 West Martin Luther King Drive, Cincinnati, Ohio 45268. Requests should include the EPA
document number found on the report's cover. When the limited supply is exhausted, additional copies can be
purchased from the National Technical Information Service, Ravensworth Building, Springfield, Virginia 22161, (703)
487-4600. Reference copies will be available at EPA libraries in the Hazardous Waste Collection. You can also call
the SITE Clearinghouse hotline at (800) 424-9346 or (202) 382-3000 in Washington, D.C., to inquire about the
availability of other reports.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
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Abstract
This report evaluates the DuPont/Oberlin microfiltration technology's ability to remove metals (present in soluble or
insoluble form) and particulates from liquid wastes while producing a dry filter cake and a filtrate that meet applicable
disposal requirements. This report also presents economic data from the Superfund Innovative Technology Evaluation
(SITE) demonstration and, as available, three case studies.
The DuPont/Oberlin microfiltration technology combines Oberlin's automatic pressure filter with DuPont's new
microporous Tyvek® filter media. It is designed to remove particles that are 0.1 micron in diameter, or larger, from liquid
wastes, such as contaminated groundwater. Groundwater with dissolved metals must first be treated to convert the dissolved
metals into an insoluble form prior to microfiltration.
The DuPont/Oberlin microfiltration technology demonstration was conducted under the SITE program at the Palmerton
Zinc Superfund site in Palmerton; Pennsylvania, in April and May 1990. During the demonstration, the microfiltration
system achieved zinc and total suspended solids (TSS) removal efficiencies of about 99.95 percent, and a filter cake solids
content of 41 percent. The filter cake contained no free liquids, and a composite sample from all the demonstration runs
passed both the extraction procedure toxicity test and the toxicity characteristic leaching procedure (TCLP) test. The filtrate
met applicable National Pollutant Discharge Elimination System permit limits for metals and TSS but not for pH; the filtrate
pH was typically 11.5 while the upper pH limit is 9.
The results from three case studies are also summarized in this report. All three facilities treated process wastewaters
containing metals and TSS ranging from several parts per million to several percent. The filtrates at all three facilities met
their respective discharge limits. Filter cake at one facility is a mixed waste and is further stabilized and solidified with
cement prior to land disposal. At another facility, filter cake did not pass the TCLP test and is considered a hazardous waste.
No filter cake information was available from the third facility.
Possible sites for applying this technology include Superfund and other hazardous waste sites that have groundwater and
other liquid wastes contaminated primarily with metals and particulates. Sources of metal-bearing wastes include electro-
plating and metal finishing facilities, electronic component manufacturers, aluminum and other metal forming facilities, and
uranium processing facilities. Economic data indicate that the capital costs for only the microfiltration unit and ancillary
equipment are $48,000 for a 2.4-square foot unit and about $232,000 for a 36-square foot unit. Annual operation and main-
tenance (O&M) costs (including analytical, labor, and disposal costs) are estimated to be about $213,000 for the smaller unit
and $549,100 for the larger unit, with corresponding annual throughputs of 525,600 gallons and 7,884,000 gallons.
IV
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Contents
Page
Foreword iii
Abstract iv
Figures vii
Tables vii
Acknowledgements viii
1. Executive Summary 1
Introduction 1
Overview of the SITE Demonstration 1
Results from the SITE Demonstration , 1
Results from the Case Studies 2
Waste Applicability 2
Economics 2
2. Introduction 3
Purpose, History, and Goals of the SITE Program 3
Documentation of the SITE Demonstration Results 3
Purpose of the Applications Analysis Report 3
Technology Description 4
Key Contacts 8
3. Technology Applications Analysis 9
Effectiveness of the DuPont/Oberlin Technology 9
Site Characteristics 12
Materials Handling Required by the Technology 13
Personnel Requirements 13
Potential Community Exposures ,13
Potential Regulatory Requirements 13
4. Economic Analysis '. 19
Site-Specific Factors Affecting Cost 19
Basis of Economic Analysis 19
References
.23
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Contents (Continued)
Appendices
A. Vendor's Claims for the Technology 25
Introduction 25
DuPont/Oberlin Microfiltration Technology : 25
Applications of the DuPont/Oberlin Microfiltration Technology 26
Summary 26
References 26
B. SITE Demonstration Results 27
Introduction 27
Site Description •. 27
Site Contamination Characteristics 27
Review of SITE Demonstration , 27
Experimental Design 30
Review of Treatment Results 31
Conclusions 35
References 46
C. Case Studies 47
Introduction 47
Case Study C-l, Westinghouse Savannah River Site, Aiken, South Carolina 48
Facility Operations 48
System Performance ; 48
Costs 50
Conclusions 50
Case Study C-2, Dupont Electronics Materials, Inc., Manati, Puerto Rico 51
Facility Operations : 51
System Performance : 51
Costs 51
Case Study C-3, DuPont Electronics, Sun Valley, California 52
Facility Operations 52
System Performance 52
Costs 52
VI
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Figures
2-1 DuPont/Oberlin Microfiltration Treatment System 5
2-2 Schematic of DuPont/Oberlin Microfiltration Unit 6
2-3 Steps in a Typical Microfiltration Unit Operating Cycle 7
B-l PZS Site Location Map 28
B-2 Microfiltration System Sampling Locations 33
B-3 Zinc Concentration Profiles for Phase 1 Runs 35
B-4 TSS Concentration Profiles for Phase 1 Runs 37
B-5 Filter Cake Solids for Phase 1 Runs 38
B-6 Zinc Concentration Profiles for Phase 2 Runs 39
B-7 TSS Concentration Profiles for Phase 2 Runs 40
B-8 Filter Cake Solids for Phase 2 Runs 41
B-9 Comparison of Filtrate Quality for Reproducibility
Runs with Regulatory Thresholds 42
B-10 Filter Cake Composition for Reproducibility Runs .,, 43
B-ll Tyvek® Performance for Reusability Runs ., 44
B-12 Filtrate Particle Size Distribution for Reproducibility Runs ; 45
Tables
2-1 Comparison of Sludge Dewatering Technologies g
3-1 Regulations Summary _ 14
4-1 Estimated Costs Associated with DuPont/Oberlin Microfiltration Systems 20
B-l Operating Conditions for the Demonstration Runs 32
B-2 Analytical and Measurement Methods 34
C-l-1 Operating Data for the DuPont/Oberlin Microfiltration System 49
VII
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Acknowledgments
This report was prepared under the direction and coordination of Mr. John Martin, U.S. Environmental Protection
Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Project Manager and Demonstration Section Chief in
the Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio. Contributors and reviewers for this report were Ms.
Linda Fiedler of EPA's Office of Solid Waste and Emergency Response, Washington, D.C.; Mr. Gordon Evans, Mr. Paul
dePercin, and Mr. Robert Stenburg of EPA RREL, Cincinnati, Ohio; Dr. Ernest Mayer of E.I. DuPont de Nemours and
Company, Inc., Newark, Delaware; and Dr. Thomas Oberlin of the Oberlin Filter Company, Waukesha, Wisconsin.
This report was prepared for EPA's SITE program by Dr. Kirankumar Topudurti, Mr. Stanley Labunski, Mr. Andrew
Suminski, Ms. Carla Buriks, Mr. Michael Keefe, and Mr. Jack Brunner of PRC Environmental Management, Inc.
VIII
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Section 1
Executive Summary
Introduction
The DuPont/Oberlin microfiltration technology was
evaluated under the U.S. Environmental Protection Agency's
(EPA) Superfund Innovative Technology Evaluation (SITE)
program. The DuPont/Oberlin microfiltration technology
demonstration was conducted at the Palmerton Zinc Superfund
(PZS) site in Palmerton, Pennsylvania, during April and May
1990. This technology is designed to remove solids that are
0.1 micron in diameter, or larger, from liquid wastes. Liquid
wastes with dissolved contaminants (for example, groundwater
with dissolved metals) must first be treated with a precipitating
agent to convert the dissolved contaminants into particulate
form. The treated waste can then be filtered through the
microfiltration unit, which produces two end products: filter
cake and filtrate. Prior to filtration, a filter aid/cake stabilizing
agent may be added to improve the filter cake's dewatering
characteristics and bind the precipitated metals to the cake.
The microfiltration unit can be manufactured as an enclosed
unit, requires little attention during operation, is transport-
able, and can be trailer mounted.
The technology demonstration had the following four
objectives:
1. Assess the technology's ability to remove zinc
from the groundwater at the PZS site under
different operating conditions
2. Evaluate the microfiltration system's ability to
dewater the metals precipitate from the treated
groundwater at the PZS site
3. Determine the system's ability to produce a
filtrate and a filter cake that meet applicable
disposal requirements
4. Develop information required to estimate the
operating costs for the treatment system
The purpose of this report is to present information from
the SITE demonstration and several case studies that are
useful for implementing the DuPont/Oberlin microfiltration
technology at Superfund and Resource Conservation and
Recovery Act (RCRA) hazardous waste sites. Section 2
presents an overview of the SITE program, describes the
DuPont/Oberlin microfiltration technology, and lists key
contacts. Section 3 discusses information relevant to the
technology's application, including pre- and post-treatment
requirements, site characteristics, operating and maintenance
requirements, potential community exposures, and poten-
tially applicable environmental regulations. Section 4 sum-
marizes the costs associated with implementing the technol-
ogy. Appendices A through C include the following: the
vendor's claims regarding the automatic pressure filter and
microporous Tyvek® filter material, a summary of the SITE
demonstration results, and three case studies.
Overview of the SITE Demonstration
The shallow groundwater at the PZS site was selected as
the waste stream for evaluating the DuPont/Oberlin
microfiltration system. This groundwater was primarily con-
taminated with high levels of zinc (400 to 500 mg/L) and
trace levels of cadmium (1 mg/L), copper (0.02 mg/L), lead
(0.015 mg/L), and selenium (0.05 mg/L). The pH and alka-
linity of the groundwater were about 4.5 and 15 mg/L as
calcium carbonate, respectively.
During the SITE demonstration, the microfiltration sys-
tem treated about 6,000 gallons of shallow groundwater from
well RCRA-4. Lime was added to the groundwater to raise
the pH and precipitate the dissolved metals. A filter aid/cake
stabilizing agent, called ProFix, was also added to the pre-
treated groundwater prior to microfiltration.
The SITE demonstration was performed in four phases
and was designed to evaluate the microfiltration system's
ability to remove zinc from the groundwater, produce a dry
filter cake, and produce a filtrate and a filter cake that met
regulatory disposal requirements. Phases 1 and 2 involved
nine runs each, and Phases 3 and 4 involved two runs each.
In Phase 1, chemical operating parameters (pH and ProFix
dose) were varied, while the filter operating parameters
(blowdown pressure and blowdown time) were kept con-
stant. In Phase 2, the filter operating parameters were varied,
while the chemical operating parameters were kept constant.
Phases 3 and 4 were performed at the overall optimum
operating conditions determined during Phases 1 and 2. Phase
3 runs were performed to evaluate the reproducibility of the
microfiltration system's performance. Phase 4 runs were
performed to evaluate the reusability of the Tyvek® filter
material.
Results from the SITE Demonstration
The following operating conditions from Phases 1 and 2
were determined to be the overall optimum operating condi-
tions for the demonstration: a precipitation pH of 9, a ProFix
dose of 12 g/L, a blowdown pressure of 38 psig, and a
blowdown time of 0.5 minute. At these optimum conditions,
the microfiltration system achieved zinc and total suspended
solids (TSS) removal efficiencies of about 99.95 percent and
a filter cake solids content of 41 percent. The zinc and TSS
removal efficiencies, and the filter cake solids content, were
unaffected by the repeated use (six cycles) of the Tyvek®
filter material. This indicates that the Tyvek® filter media
1
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could be reused without adversely affecting the microfiltration
system's performance.
The filter cake passed the paint filter liquids test in all
the demonstration runs. Also, a composite filter cake sample
from the 22 demonstration runs passed both the extraction
procedure toxicity and toxicity characteristic leaching proce-
dure (TCLP) tests. This indicates that the filter cake cpuld
be disposed of in a non-hazardous waste landfill. PrpFix
comprised between 80 and 90 percent of the filter cake
solids. The remaining solids consisted of precipitated met-
als, TSS from the groundwater, and any unreacted lime.
The filtrate met the applicable National Pollutant Dis-
charge Elimination System (NPDES) permit limits, estab-
lished for disposal into a local waterway, for metals and TSS
at the 95 percent confidence level. However, the filtrate did
not meet the NPDES limit for pH. The filtrate pHlwas
typically 11.5, while the upper pH limit is 9. This indicates
that the filtrate may require pH adjustment prior to disposal.
Results from the Case Studies
Information on the DuPont/Oberlin microfiltration
technology's performance at three facilities was evaluated to
provide additional performance data. These facilities were:
1. Westinghouse Savannah River Site, Aiken,
South Carolina
2. DuPont Electronics Materials, Inc., Manati,
Puerto Rico
3. DuPont Electronics, Sun Valley, California
Facility 1 treats process wastewaters from metal finish-
ing and aluminum forming operations and from an autoclave
testing operation. Wastewaters from the first two operations
contain 3 mg/L of uranium, 180 mg/L of aluminum, 12 mg/L
of nickel, and generally low levels of lead, chromium, copper,
and zinc, mostly in dissolved form. These wastewaters
undergo equalization, precipitation, flocculation,, and
microfiltration. Wastewater from the autoclave operation
contains 16 mg/L of uranium oxides and undergoes only
equalization and microfiltration. Prior to microfiltration, a
filter aid (PerFLO 30SP) and a cationic polymer (Praestol
K144L) are added to the pretreated waste. The filtrate meets
all NPDES permit limits (uranium, other metals, pH, and
TSS). The filter cake is a mixed waste containing 'both
hazardous and radioactive material. Prior to disposal, the
filter cake is stabilized and solidified with cement and is
subject to land disposal restrictions.
Facility 2 produces about 2,000 gallons per day of
wastewater containing 1,000 to 5,000 parts per million (ppm)
of glass paniculate matter, called frit, and 2,000 to 10,000
ppm of TSS. This wastewater does not require pretreatrhent;
however, prior to microfiltration, a volcanic aluminum sili-
cate filter aid and an organic polymer are added to the
wastewater. After microfiltration, the filtrate passes through
two cartridge filters arranged in series. These additional
filters, rated at 10 microns and 1 micron, are provided to
ensure high removal of particulates. According to the facil-
ity, the microfiltration system removes nearly all paniculate
matter.
Facility 3 generates wastewater from its ceramic powder
manufacturing process. Wastewater characteristics vary daily,
depending on the specific operations performed. Generally,
the wastewater contains, a mixture of metal oxides and titan-
ates. Lead and TSS levels typically range from 0.5 to 5
percent. Pretreatment is not needed since most metals are in
the form of suspended solids. However, prior to
microfiltration, a diatomaceous earth filter aid and a polymer
(Praestol K122L) are added to improve the cake solids con-
tent and its dewatering characteristics. The filtrate meets all
local sewer discharge limits and contains typically 0.2 to 0.4
ppm of soluble lead and 5 ppm of TSS. The filter cake
contains about 50 percent solids, but it is considered a haz-
ardous waste based on TCLP test results. DuPont plans to
use ProFix in lieu of diatomaceous earth to eliminate off-site
stabilization and reduce operating costs.
Operating and maintenance costs are minimal at all three
facilities, and no major operating problems have been cited.
Waste Applicability
The DuPont/Oberlin microfiltration technology can be
applied to groundwater and industrial wastewaters containing
metals in paniculate form and other suspended solids. Met-
als in dissolved form must first be converted to an insoluble
form prior to microfiltration. Potential sites for applying this
technology to contaminated groundwater include Superfund
and RCRA corrective action sites where groundwater is
contaminated with metals from electroplating/metal finishing
wastes, semiconductor and other electronic component
manufacturing waste streams, metal forming and uranium
manufacturing wastes, and other sources of metal-bearing
wastes.
Economics
An economic analysis was performed that examined 12
separate cost categories for two microfiltration systems: a
2.4-square foot unit, similar to the unit used during the SITE
demonstration, and a 36-square foot unit, the largest unit
currently in use. This analysis assumed that the microfiltration
systems would operate continuously (24 hours per day, 7
days per week) for 1 year. The economic analysis covered a
1-year period so that annual operation and maintenance
(O&M) costs could be reliably estimated. Annual O&M
costs were estimated to be $213,000 and $549,100 for the
2.4- and 36-square foot units, respectively, with correspond-
ing annual throughputs of 525,600 gallons and 7,884,000
gallons. The cost analysis assumes that the filter cake and
filtrate will be disposed of as non-hazardous wastes. One-
time capital costs were $369,300 for the smaller unit and
$1,251,200 for the larger unit. Minimal cost data were avail-
able from the case studies presented in Appendix C. How-
ever, one of the case study facilities provided an O&M cost
of $5 per 1,000 gallons of wastewater treated. This cost
included electricity and expenses for replacing polymer, fil-
ter aid, and filter media.
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Section 2
Introduction
This section provides background information about the
Superfund Innovative Technology Evaluation (SITE) pro-
gram, discusses the purpose of this applications analysis
report, and describes the DuPont/Oberlin microfiltration
technology. The persons to be contacted for additional
information about mis technology, the SITE program, and
the demonstration site are listed at the end of this section.
Purpose, History, and Goals of the SITE Program
In response to the Superfund Amendments and
Reauthorization Act of 1986 (SARA), EPA's Office of Re-
search and Development (ORD) and Office of Solid Waste
and Emergency Response (OSWER) established the SITE
program to (1) accelerate the development, demonstration,
and use of new or innovative technologies to clean up
Superfund sites, (2) foster further investigation and develop-
ment of treatment technologies that are still at the laboratory
scale, and (3) demonstrate and evaluate new or innovative
measurement and monitoring technologies.
The primary purpose of the SITE program is to enhance
the development and demonstration, and thereby promote the
commercial availability, of innovative technologies appli-
cable to Superfund sites. Major goals of the SITE program
are to:
Identify and remove impediments to the
development and commercial use of alternative
technologies
• Demonstrate the more promising innovative
technologies in order to establish reliable
performance and cost information for site
cleanup decision making
• Develop procedures and policies that encourage
selection of available alternative treatment
remedies at Superfund sites
• Structure a development program that nurtures
emerging technologies
EPA recognizes that a number of forces inhibit the
expanded use of alternative technologies at Superfund sites.
One of the objectives of the program is to identify these
impediments and remove them or develop methods to pro-
mote the expanded use of alternative technologies.
Another objective of the SITE program is to demon-
strate and evaluate selected technologies. This is a signifi-
cant ongoing effort involving ORD, OSWER, EPA Regions,
and the private sector. The demonstration program serves to
test field-ready technologies and provide Superfund decision
makers with the information necessary to evaluate the use of
these technologies for future cleanup actions.
Other aspects of the SITE program include developing
procedures and policies that match available technologies
with wastes, media, and sites for actual remediation, and
providing assistance in nurturing the development of emerg-
ing innovative technologies from the laboratory- or bench-
scale to the full-scale stage.
Technologies chosen for a SITE demonstration must be
innovative, pilot- or full-scale applications and offer some
advantage over existing technologies. Mobile technologies
are of particular interest. Each annual round of demonstrations
includes approximately 10 technologies.
Documentation oj'the SITE Demonstration Results
The results of each SITE demonstration are incorporated
in two documents: the technology evaluation report and the
applications analysis report. The technology evaluation re-
port provides a comprehensive description of the demonstra-
tion and its results. A likely audience for the technology
evaluation report are engineers resiponsible for performing an
in-depth evaluation of the technology for a specific site and
waste situation. These technical evaluators seek to under-
stand, in detail, the performance of the technology during the
demonstration and the advantages, risks, and costs of the
technology for the given application. This information is
used to produce conceptual designs in sufficient detail for
evaluators to make preliminary cost estimates for the demon-
strated technology.
The applications analysis report is intended for technical
decision makers responsible for screening available remedial
alternatives. The principal use of the applications analysis
report is to assist in determining whether the specific tech-
nology should be considered further as an option for a par-
ticular cleanup situation. The report discusses the advan-
tages, disadvantages, and limitations of the technology in its
broadest application. Costs of the technology for different
applications are estimated based on available data for pilot-
and full-scale applications. The report discusses the factors,
such as site and waste characteristics, that have a major
impact on cost and performance. If the candidate technology
appears to meet the needs of the site engineers, a more
thorough analysis will be conducted, based on the technol-
ogy evaluation report, applications analysis report, and infor-
mation from remedial investigations for the specific site.
Purpose of the Applications Analysis Report
To encourage the general use of demonstrated technolo-
gies, EPA will provide information on the applicability of
each technology to certain sites and wastes, other than those
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already tested, and will study the costs of these applications.
Available information and data are presented through the
applications analysis reports. These reports attempt to syn-
thesize available information on the technology and draw
reasonable conclusions as to its broad range applicability.
The applications analysis report is useful to those consider-
ing the technology for Superfund and other hazardous waste
site cleanups and represents a critical step in the develop-
ment and commercialization of the treatment technology.
Each SITE demonstration will evaluate the performance
of a technology in treating a particular waste found at the
demonstration site. To obtain data with broad applications,
attempts will be made to select waste frequently found at
other Superfund sites. In many cases, however, the waste at
other sites will differ in some way from the waste tested.
Thus, the successful demonstration of a technology at one
site does not ensure that it will work equally well at other
sites. Data obtained from the demonstration may have to be
extrapolated to estimate the total operating range over which
the technology performs satisfactorily. .This extrapolation
should be based upon both demonstration data and other
information available from case studies about the technology.
The amount of available data for the evaluation of an
innovative technology varies widely. Data may be limited to
laboratory tests on synthetic wastes or may include perfor-
mance data on actual wastes treated at pilot- or full-scale
treatment systems. In addition, there are limits to conclusions
regarding Superfund applications that can be drawn from a
single field demonstration. A successful field demonstration
does not necessarily ensure that a technology will be widely
applicable or fully developed to a commercial scale.
Technology Description
In February 1988, E.I. DuPont de Nemours and Com-
pany, Inc. (DuPont) and Oberlin Filter Company (Oberlin)
submitted to EPA a joint proposal for demonstrating their
microfiltration technology under the SITE program. EPA
selected the DuPont/Oberlin microfiltration technology for
demonstration under the SITE program in June 1988.
DuPont/Oberlin's microfiltration technology is designed
to remove solids from liquid wastes. It is suitable for treating
landfill leachate, groundwater, and liquid industrial wastes
containing metals (in soluble or insoluble form) and particu-
lates. Since the microfiltration system is designed to remove
particles that are 0.1 micron or larger in diameter, dissolved
contaminants must first be converted to a paniculate fprm.
For example, groundwater with dissolved metals must \ first
be treated with a precipitating agent, such as lime, to convert
the dissolved metals into paniculate form, such as metal
hydroxides. After the dissolved metals are converted to a
paniculate form, the liquid waste can be filtered through the
microfiltration unit The microfiltration unit produces; two
end products: filter cake and filtrate. To produce a filter cake
that has a low moisture content and a filtrate that has a low
solids content, DuPont/Oberlin normally uses a filter aid or
filter aid/cake stabilizing agent. For the SITE demonstration
conducted at thePZS site during April and May 1990, DuPont
selected a silicate-based filter aid/cake stabilizing agent known
as ProFix, which is manufactured by EnviroGuard, Inc. of
Houston, Texas.
The microfiltration system can be manufactured as an
enclosed unit, requires little attention during operation, is
mobile, and can be trailer mounted. A typical configuration
of the DuPont/Oberlin microfiltration system (including pre-
treatment and principal treatment operations) to treat ground-
water contaminated with dissolved metals is shown in Figure
2-1. Since the pretreatment operations (for example, pH
adjustment and filter aid addition) of the microfiltration tech-
nology vary from one application to another, these opera-
tions are not described in this section. However, a discus-
sion on pretreatment operations is presented in Section 3
under "Factors Influencing Effectiveness." Principal treat-
ment operations of the microfiltration technology and its
innovative features are described below.
Principal Treatment Operations
A schematic of the DuPont/Oberlin microfiltration unit
is shown in Figure 2-2. This microfiltration unit is an
automatic pressure filter that operates on pressure signals and
uses a low-cost membrane filter, Tyvek® T-980, a thin, du-
rable spunbonded olefin fabric developed by DuPont. The
microfiltration unit, developed by Oberlin, has two cham-
bers, an upper chamber for feeding waste through the filter
media, and a lower chamber for collecting the filtrate. The
upper chamber moves vertically, while the lower chamber is
fixed. The Tyvek® filter lies between these two chambers.
These units are available in several sizes: the smallest unit
has a filtering area of 2.4 square feet and the largest unit has
a filtering area of 36 square feet. According to the technol-
ogy developers, about 40 percent of the units in operation
have the 2.4-square foot filtering area. The unit used in the
SITE demonstration also has a filtering area of 2.4 square
feet and is 64 inches long, 33 inches wide, 83 inches high,
and weighs approximately 1,300 pounds.
A typical operating cycle of the microfiltration unit con-
sists of four steps: (1) initial filtration/filtrate recirculation;
(2) main filtration/cake forming; (3) cake drying; and (4)
cake discharge. Figure 2-3 shows the steps involved in the
operation of the microfiltration unit.
At the start of a typical filtration cycle, the upper cham-
ber is lowered to form a liquid-tight seal against the Tyvek®.
The liquid feed waste containing paniculate matter is then
pumped, at an initial air pressure of 10 psig, into the upper
chamber and filtered through the Tyvek*. During this pro-
cess, solids are deposited on the Tyvek® filter. This solids
buildup increases resistance to liquid flow through the Tyvek®.
To keep the filtration rate constant, air pressure to the pump
is automatically increased throughout the filter cycle. During
the initial 30 seconds to 1 minute of the cycle, the filtrate is
recirculated to the precipitation tank to keep the quality of
filtrate high. At the end of 1 minute, recirculation stops and
the filtrate is drained to the filtrate collection tank.
Liquid waste is pumped to the microfiltration unit until
the air pressure to the pump reaches 55 psig (a pressure drop
of approximately 45 psig across the filter). Liquid feed waste
to the microfiltration unit is then shut off, and pressurized air
(30-45 psig) is fed into the upper chamber to dry the filter
cake. The air forces any liquid remaining in the upper cham-
ber and in the filter cake pores to pass through the Tyvek®
into the lower chamber. The air pressure applied to drain the
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Groundwater
Filter Cake
Filter Cake
Storage
LX
Lime Slurry Tank
ProFix Slurry Tank
Figure 2-1. DuPont/Oberlin MicrofMiration Treatment System.
liquid remaining in the upper chamber, and dry the filter
cake, is called the blowdown pressure. Once the liquid is
drained from the upper chamber and the filter cake, air
breaks through the filter cake. After breakthrough occurs, air
continues to be fed through the upper chamber for a preset
time interval to further dry the cake. The preset time interval
is called the blowdown time. During the cake drying period,
the filtrate is sent back to the precipitation tank to keep the
quality of filtrate high. At the end of the blowdown time, the
air supply to the upper chamber is automatically shut off, the
upper chamber is raised, and the filter cake is automatically
discharged. Clean Tyvek® is then drawn from a roll into the
microfiltration unit for the next cycle.
Innovative Features
The DuPonl/Oberlin microfiltration technology uses a
new, low cost membrane filter (Tyvek® T-980) that can be
fed continuously to an automatic pressure filter to dewater
sludges effectively. Through proper pretreatment, such as
chemical precipitation, this technology can be used to re-
move dissolved metals from liquid wastes at a cost lower
than several other treatment options, such as precipitation
followed by clarification and conventional filtration, ion ex-
change, reverse osmosis, and electrolysis. When used in
conjunction with a filter aid/cake stabilizing agent, the DuPont/
Oberlin microfiltration technology produces a dry and stabi-
lized cake that can be landfilled.
The DuPont/Oberlin microfiltration system has several
innovative features that make it more effective than conven-
tional microfiltration systems. The most significant of these
features is DuPont's Tyvek® T-980 filter media, which is
designed to remove particles that are 0.1 micron or larger in
diameter. The high strength of this media, under both wet
and dry conditions, permits continuous operation in the
microfiltration unit. Also, the smooth, slick surface of the
Tyvek® T-980 media facilitates cake release and separation.
Pressure filters such as the DuPont/Oberlin microfiltration
units are becoming a more popular means of dewatering
sludges and removing precipitated, metals from liquid waste
streams. Pressure filters generally produce a filter cake with
a solids content high enough to meet landfill requirements,
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Pressurized
Air
Air Cylinder
Waste
Feed
Filter Cake
Used Tyvek
Air Bags
Waste Feed Chamber
®
Clean Tyvek
Filter Belt
Filtrate Chamber
Filtrate
Discharge
Rgure 2-2. Schematic of DuPont/Oberlin Microfiltration Unit.
giving it a significant advantage over other dewatering meth-
ods. Also, automation makes pressure filters more appeal-
ing. Table 2-1 compares several sludge dewatering options.
The DuPont/Oberlin microfiltration technology i uses
Oberlin's automatic pressure filter, which has certain advan-
tages over other conventional pressure filters.' The
microfiltration unit uses a continuous roll of filter media and
automatically dispenses the filter cake, eliminating the;need
for add-on systems such as plate shifters and cake vibrators.
When used in conjunction with the Tyvek® T-980 media, the
system can effectively dewater sludge at a maximum pres-
sure of 30 to 50 psig, requiring less energy than other
pressure filters, which may operate at a maximum pressure
above 200 psig. Also, the Tyvek® T-980 media is dispensed
from a roll and the cake discharge is fully automated. The
automatic cake discharge and electronic controls, based on
either discrete relays and timers or programmable logic con-
trol, enable the microfiltration unit to run without significant
operator attention, except for filter aid makeup, media roll
replacement, and cake removal.
-------
/. INITIAL FILTRATION/FILTRATE RECIRCULAVON 2. MAIN FILTRATION/CAKE FORMING
Pressurized Air
\
i Valve B (Closed)
Valve A (Open)
IMM^^^ _ Waste
Feed
Air Bags
Waste Feed Chamber
nitrate
Chamber
Clean Tyvek
Reclrculatton
Valve D (Closed)
Filter
Cake
Filtrate
nitrate
Collection
. Waste
Feed
M D (Open)
Filtrate
Collection
3. CAKE DRYING
4. CAKE DISCHARGE
Filter
Cake
Filtrate
Pressurized Air
\
( B (Open)
A (Closed)
A i
D (Closed)
B (Closed)
Waste Feed
Chamber Raised
Clean Tyvek
Advanced
IH D (Closed)
Figure 2-3. Steps in a Typical Microfiltration Unit Operating Cycle.
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Table 2-1. Comparison of Sludge Dewatering Technologies
Technology Advantages ^^
Disadvantages
Basket Centrifuge
Low energy consumption; low chemical
consumption; low labor requirements;
prescreening not required
Low cake solids content
Solid Bowl Centrifuge
Low chemical consumption; low
labor requirements
Low cake solids content; prescreening required;
high energy consumption
Vacuum Filter
Sludge Drying Bed
Low labor requirements
Low cake solids content; high energy consumption;
high chemical consumption; prescreening required
High cake solids content possible; High labor requirements; large land area
low energy consumption; low chemical consumption; requirements; climatic influences; aesthetically
prescreening not required unpleasing
Gravity/Low Pressure Device
Low energy consumption; low labor
requirements; prescreening npt required
Low cake solids content; high chemical consumption
Bell Filter Press
High cake solids content; low energy consumption Prescreening required; high chemical consumption;
high labor requirements
Plate Hlter Press
Very high cake solids content
Prescreening required; high chemical consumption;
high labor requirements; high energy consumption
Pressure Filter
Very high cake soh'ds content; low labor requirements Prescreening required; high chemical consumption;
high energy consumption
Note: Based on U.S. EPA, 1982.
Key Contacts
Additional information on the DuPont/Oberlin
microfiltration technology, the SITE program, and the
Palmerton Zinc Superfund site (demonstration site) can be
obtained from the following sources:
The DuPont/Oberlin Microfiltration Technology
Ernest Mayer
E.I. DuPont de Nemours and Company, Inc.
Engineering Department L1359
P.O. Box 6090
Newark, DE 19714-6090
(302) 366-3652
Thomas Oberlin
Oberlin Filter Company
404 Pilot Court
Waukesha,WI 53188
(414) 547-4900
The SITE Program
John Martin
U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7758
The Palmerton Zinc Superfund Site
Tony Koller
U.S. Environmental Protection Agency
Region 3 (3HW22)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-6906
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Section 3
Technology Applications Analysis
This section addresses the applicability of the DuPont/
Oberlin microfiltration technology to treat liquid wastes con-
taining paniculate matter and metals in suspended or dis-
solved form. The technology's applicability is presented
based on the results from the DuPont/Oberlin microfiltration
system demonstration performed under the SITE program
and other applications of the DuPont/Oberlin system pre-
sented in Appendix C. Since the results of the SITE demon-
stration provided an extensive database, evaluation of the
technology's effectiveness and its applicability to other po-
tential cleanup operations is mainly based on the SITE dem-
onstration results presented in Appendix B. The vendor's
claims regarding the applicability and performance of the
DuPont/Oberlin microfiltration technology are included in
Appendix A.
A summary of the effectiveness of the DuPont/Oberlin
microfiltration technology is presented in this section, fol-
lowed by a discussion of site characteristics, materials handling
requirements, personnel requirements, potential community
exposures, and potential regulatory requirements for the
DuPont/Oberlin technology.
Effectiveness of the DuPont/Oberlin Technology
The effectiveness of the DuPont/Oberlin technology is
presented based on the results from the SITE demonstration
and three other case studies of the technology. After sum-
marizing the results from the SITE demonstration and the
case studies, this report describes factors influencing the
effectiveness of the technology.
SITE Demonstration Results
The SITE demonstration was conducted at the Palmerton
Zinc Superfund (PZS) site in Palmerton, Pennsylvania, dur-
ing April and May 1990. During the SITE demonstration, the
microfiltration system treated 6,000 gallons of groundwater
contaminated with high levels of zinc (400 to 500 mg/L) and
trace levels of cadmium (1 mg/L), copper (0.02 mg/L), lead
(0.015 mg/L), and selenium (0.05 mg/L).
The objectives of the DuPont/Oberlin microfiltration
technology demonstration performed under the SITE pro-
gram were to:
• Assess the technology's ability to remove zinc
from the groundwater at the PZS site under
different operating conditions
• Evaluate the microfiltration system's ability to
dewater the metals precipitate from treated
groundwater at the PZS site
Determine the system's ability to produce a
filtrate and a filter cake that meet applicable
disposal requirements
Develop information required to estimate the
operating costs for the treatment system, such
as electrical power consumption and chemical
doses
The technology evaluation was performed in four phases.
Phases 1 and 2 involved nine runs each, and Phases 3 and 4
involved two runs each. In Phase 1, chemical operating
parameters (precipitation pH and ProFix dose) were varied,
and the filter operating parameters (blowdown pressure and
blowdown time) were kept constant. In Phase 2, the filter
operating parameters were varied, and the chemical operat-
ing parameters were kept constant. Phase 3 runs were per-
formed to evaluate the reproducibility of the microfiltration
system's performance. Phase 4 runs were performed to evalu-
ate the reusability of the Tyvek® filter.
Appendix B summarizes information from the SITE
demonstration, including (1) site characteristics, (2) contami-
nated groundwater characteristics, (3) microfiltration system
performance, and (4) technology evaluation results. Key
findings of the demonstration are given below.
The DuPont/Oberlin microfiltration system
achieved the following: (1) zinc and total
suspended solids (TSS) removal efficiencies of
99.69 to 99.99 percent and (2) solids in the
filter cake of 30.5 to 47.1 percent. At the overall
optimum conditions (precipitation pH of 9,
ProFix dose of 12 g/L, blowdown pressure of
38 psig, and blowdown time of 0.5 min.), the ,
zinc and TSS removal efficiencies were about
99.95 percent, and the filter cake solids were
about 41 percent.
ProFix contributed a significant portion (80 to
90 percent) of solids to the filter cake. The
remaining solids were due to precipitated metals,
TSS from the untreated groundwater, and any
unreacted lime.
The zinc and TSS removal efficiencies and the
filter cake percent solids were unaffected by the
repeated use (six cycles) of the Tyvek® filter
media. This indicates that the Tyvek® media
could be reused without adversely affecting the
microfiltration system's performance.
The filtrate met the applicable National Pollutant
Discharge Elimination System (NPDES) permit
-------
limits, established for discharge into a local!
waterway, for metals andTSS at the 95 percent
confidence level. However, the filtrate did not
meet the NPDES limit for pH. The filtrate pH
was typically 11.5, while the upper discharge
limit is 9.
• The filter cake passed the paint filter liquids
test for all runs. Also, a composite filter cake
sample from the demonstration runs passed the
extraction procedure (EP) toxicity and toxicity
characteristic leaching procedure (TCLP) tests.
Other Case Studies' Results
Several other studies on the DuPont/Oberlin
microfiltration system have been carried out. DuPont/Oberlin
has made the results from three case studies available to
EPA. These studies are summarized in Appendix C. A brief
summary of the effectiveness of the DuPont/Obeirlin
microfiltration technology at the three facilities is presented
below.
The first case study describes the effectiveness of two
DuPont/Oberlin microfiltration units in treating wastewaters
from a metal finishing and aluminum forming operation and
from an autoclave process both at the Westinghouse Savan-
nah River site in Aiken, South Carolina. The wastewater
from metal finishing and aluminum forming operations con-
tains about 3 mg/L of uranium, 180 mg/L of aluminum', 12
mg/L of nickel, and low levels of lead, zinc, copper, and
chromium mostly in dissolved form. The wastewater from
the autoclave process contains about 16 mg/L of insoluble
uranium oxides.
At the Savannah River site, wastewater containing soluble
metals is treated by equalization, precipitation, flocculation,
and microfiltration, and wastewater containing insoluble metal
oxides is treated by equalization and microfiltration. ;The
Savannah River site used Tyvek® 1042B as the filter media
for several years. However, during peak flow situations, the
two DuPont/Oberlin systems could not provide adequate
treatment. Therefore, DuPont conducted several tests to im-
prove the treatment capacity of the filters. During these tests,
DuPont's efforts to upgrade the microfiltration systems in-
cluded using'new filter media (Tyvek"1 T-980), filter aidi and
polymer additive.
Performance of the microfiltration systems was maxi-
mized and their combined capacity was upgraded by using
Tyvek* T-980 filter media, in conjunction with PerFLO
30SP filter aid and Praestol K144L cationic polymer. The
volume of filter cake requiring disposal decreased by 15
percent. The filtrate and filter cake met both EP toxicity and
TCLP tests. The filtrate also met all NPDES requirements.
The filter cake is solidified and stabilized with cement prior
to its disposal as a mixed waste.
The second case study describes the removal of particu-
late matter present in a wastewater slurry at the DuPont
Electronics Materials, Inc. (DEMI) facility in Manati, Puerto
Rico. DEMI produces a wastewater slurry at a rate of 2,000
gallons per day. The slurry contains 1,000 to 5,000 parts per
million (ppm) of glass particulates and 2,000 to 10,000 :ppm
of TSS. The plant uses a filter aid and an organic polymer
prior to microfiltration. The microfiltration unit uses Tyvek®
T-980 filter media. After microfiltration, the filtrate passes
through two cartridge filters arranged in series. These addi-
tional filters, rated at 10 microns and 1 micron, are provided
to ensure high levels of paniculate removal. According to
DEMI, the microfiltration system removes nearly all panicu-
late matter.
The third case study describes the removal of suspended
metals from two liquid waste streams produced by the Com-
ponent Materials Division of the DuPont Electronics facility
located in Sun Valley, California. The compositions of the
two waste streams vary according to daily operations at this
facility. However, lead and TSS levels typically range from
0.5 to 5 percent. The facility uses two 7-square foot
microfiltration units that are in two different locations 1/4 -
mile apart. The microfiltration units use Tyvek® T-980 filter
media, a filter aid, and a polymer.
The filtrate meets Los Angeles sewer effluent limits of
26 ppm and 5 ppm for TSS and zinc, respectively. The
moisture content of the filter cake is about 50 percent. The
filter cake is classified as hazardous waste because it fails the
TCLP test. DuPont plans to use ProFix instead of diatoma-
ceous earth to eliminate off-site stabilization and reduce
operating costs.
In summary, the DuPont/Oberlin microfiltration technol-
ogy has been demonstrated to be effective in removing TSS
and metals (soluble and insoluble) from liquid wastes. The
technology has also been demonstrated to produce a filter
cake of 40 to 50 percent solids that passes the paint filter
liquids test, making the filter cake suitable for land disposal.
However, whether the filter cake must be disposed of as a
hazardous waste or non-hazardous waste has to be deter-
mined on a case-by-case basis. Also, in some cases, the
filtrate may require post-treatment for pH adjustment prior to
discharge into a waterbody.
Factors Influencing Effectiveness
Several factors influence the effectiveness of the DuPont/
Oberlin microfiltration technology. These factors can be
grouped into three categories: (1) waste characteristics, (2)
operating parameters, and (3) maintenance requirements. Each
of these is discussed below.
Waste Characteristics
The ability of the DuPont/Oberlin microfiltration system
to remove dissolved metals depends on certain key waste
characteristics. These include organic and inorganic ligands
(a negatively charged ion or a molecule that forms a complex
with positively charged metal ions), the oxidation state of
metallic contaminants, and oil and grease. Several organic
and inorganic ligands can complex with metals and make the
metals less amenable to precipitation. Organic ligands such
as amino acids and humic compounds are known to form
complexes with several heavy metals (for example, with
copper). Inorganic ligands such as ammonia, cyanide, and
chloride are known to form stable complexes with zinc, iron,
and mercury, respectively. Therefore, it is important to mea-
sure the ligand concentrations and properly design the pre-
treatment operations to precipitate metals effectively. Another
key waste characteristic is the oxidation state of metallic
10
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contaminants. For example, hexavalent chromium is less
amenable to precipitation than trivalent chromium. Therefore,
if chromium is present in the hexavalent state, it needs to be
reduced to the trivalent state prior to precipitation for effective
removal. In addition to these waste characteristics, high lev-
els of oil and grease may decrease the system's treatment
efficiency.
Operating Parameters
Operating parameters are those parameters that are var-
ied during treatment to achieve desired removal efficiencies.
Typically, such parameters include precipitation pH, filter
aid/cake stabilizing agent (for pretreatment, if required),
blowdown time, and blbwdown pressure (for microfiltration
of sludge). In addition to these parameters, several other
operating parameters become important depending on the
type of pretreatment required. For example, if metals need to
be oxidized or reduced prior to precipitation, the oxidant or
reductant dose and the pH at which this pretreatment must be
carried out will have to be controlled properly. Only the
typical operating parameters are discussed in this report.
Precipitation pH depends on the metal to be precipitated
and the type of solid phase formed during precipitation (hy-
droxide, carbonate, or sulfide). The solubility of most metals
follows a U-shape curve because of the amphoteric nature of
most solid phases formed during metal precipitation. This
indicates that usually there is an optimum pH or pH range at
which the solubility of a given metal is at its minimum. The
removal of this metal from liquid wastes can be maximized
by keeping the precipitation pH close to the optimum. In a
real-world situation, however, the liquid wastes will have
either multiple pH optima or an overall optimum pH range.
Such situations may require conducting sequential precipita-
tion of metals (in case of multiple optima) or setting the
precipitation pH in the overall optimum range (in case of no
multiple optima). Selection of precipitation pH could be-
come more difficult, if the liquid waste contains ligands that
form complexes with target metals. In such a case, the
precipitation pH should be selected such that the metal com-
plexation is minimized. However, if such an approach does
not yield adequate metal removal, the ligand and/or complex
should be removed prior to metal precipitation.
DuPont normally uses a filter aid to improve sludge
dewatering characteristics or a filter aid/cake stabilizing agent
to stabilize the cake and improve sludge dewatering charac-
teristics. DuPont normally screens several commercial prod-
ucts for each application. Typically, higher chemical additive
doses are required to meet TCLP limits. However, a higher
dose also results in greater chemical costs and more dry
solids handling.
Blowdown pressure is the pressure at which air is ap-
plied to drain residual liquid from filter cake pores during the
cake drying step of a filtration cycle. Blowdown time is the
time for which air is applied after it breaks through the filter
cake. Since blowdown pressure and blowdown time control
the filter cake dryness, these are the key operating param-
eters of the DuPont/Oberlin microfiltration unit. The higher
the values of these parameters, the higher will be the filter
cake dryness. However, it should be noted that as the target
blowdown pressure increases, so will the required capacity
and pressure rating of the air compressor. Also the filtration
cycle time (processing time) will increase, if the blowdown
time is increased.
Maintenance Requirements
The maintenance requirements for the DuPonl/Oberlin
system summarized here are based on a review of the opera-
tion and maintenance manual for the microfiltration unit
(Oberlin, 1984) and other published literature (WPCF, 1984;
Karassik, 1986). Regular maintenance by trained personnel
is essential for the system's successful operation. The fol-
lowing components require routine maintenance: (1)
microfiltration unit, (2) air compressor, (3) pumps, and (4)
miscellaneous components. A brief summary of the mainte-
nance requirements for each of these components is pre-
sented below.
The microfiltration unit hais several components that
require periodic maintenance. For example, the platen seals
in both the upper and lower platens (chambers) will wear out
and need replacement approximately once a year. Similarly,
air bags will wear out and need replacement once every 3 to
5 years. Seals in the air cylinder (located on the top of the
filter frame) will also age and leak air. If properly lubricated,
these will require replacement approximately once every 5
years. Standard leak checks should be performed once a
month to identify when platen seals or air bags need re-
placement. The Tyvek® filter media roll also needs to be
replaced, as needed. Several moving parts, such as the air
cylinder and pillow block beaiings, should be lubricated
with proper lubricants once every 6 months for smooth
operation of the DuPont/Oberlin unit.
Oberlin normally uses a reciprocating type of compres-
sor to supply pressurized air to I'Jie microfiltration unit. The
compressor valves should be removed and inspected after
the first 3 months of operation. The condition of the valves
after this initial inspection will serve as a guide to the
frequency of future inspections. It is generally recommended
that the valves be inspected at least once a year. The
compressor's shaft packing should also be inspected at fre-
quent intervals, and this packing should be adjusted or re-
placed as often as required. Bearing and piston clearances,
rod alignment, and cylinder bore condition should be checked
at least annually and adjustments or replacements made to
correct any abnormal conditions. Since the microfiltration
unit has pneumatic controls, a moisture trap and an air dryer
should be installed at the discharge end of the compressor to
prevent malfunctioning of the microfiltration unit.
The operation of the DuPont/Oberlin microfiltration
system typically requires three to four pumps. Since the
type, size, design, and construction materials of these pumps
may vary from one application to the other, the operators
should review the manufacturer's instruction manuals before
attempting to service any of the pumps. Only general guide-
lines regarding the maintenance of the pumps are outlined
below. Pumps should be checked twice each shift (When
the operators are on duty), and any irregularities in their
operation should be addressed immediately following
manufacturer's guidelines. This applies particularly to changes
in the sound of a running pump, abrupt changes in bearing
temperatures, and stuffing box leakage. The free movement
11
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of stuffing box glands should be checked semiannually, gland
bolls should be cleaned and oiled, and the packing should be
inspected to determine whether it requires replacement. The
pump and driver alignment should be checked and corrected
if necessary. Oil-lubricated bearings should be drained and
refilled with fresh oil. Grease-lubricated bearings should be
checked to see that they contain the correct amount of grease
and that the grease is still of suitable consistency. During
semiannual inspections, worn out bearings should be re-
placed. A complete overhaul of the pumps is required peri-
odically for smooth operation. The frequency of complete
pump overhauls will depend on the pump service, the pump
construction and materials, the liquid pumped, and an evalu-
ation of the costs of overhaul versus the cost of power losses
resulting from increased clearances or of unscheduled down-
time. Some pumps on very severe service may need a cbm-
plete overhaul monthly, while other applications may require
overhauls only every few years.
Other components of the DuPont/Oberlin microfiltration
system, such as valves, flow meters, and pipelines, should be
checked for leaks and clogging. The metals precipitation
tank, lime slurry tank, filter aid/cake stabilizing agent slurry
tank, and filtrate collection tank should also be checked for
leaks. Finally, the electrical motors for the mixers used in
tanks should be maintained following manufacturer's guide-
lines.
Site Characteristics
In addition to influent characteristics and effluent dis-
charge requirements, site characteristics are important when
considering the use of DuPont/Oberlin's microfiltration tech-
nology. Site-specific factors have both positive and negative
impacts on the application of DuPont/Oberlin's technology,
and these should be considered before this technology is
selected for site remediation. These factors include site grea,
site preparation, site access, climate, utilities, and services
and supplies.
Site Area
DuPont/Oberlin units are available in several sizes, with
filtration areas ranging from 2.4 to 36 square feet. During the
SITE demonstration, a 2.4-square foot unit was used. An
area of 30 feet in length and 20 feet in width was adequate
for the DuPont/Oberlin unit and associated equipment, ex-
cluding influent and effluent storage tanks. Larger units
would require slightly larger areas. For example, for the; 36-
square foot unit, an area of 50 feet in length and 30 feet in
width should be provided. Areas required for influent ;and
effluent storage tanks, if needed, may vary depending ort the
flow rate and turnaround time for any effluent analysis re-
quired prior to disposal of the effluent. Also, an area of 20
feet in length and 15 feet in width is required for indoor
office space and any on-site laboratory work.
Site Preparation
The area containing the DuPont/Oberlin system tanks
should be relatively level. It can be paved or covered with
compacted soil or gravel. The site geotechnical characteris-
tics (for example, soil bearing capacity) should be evaluated
to identify whether any foundation is required to support the
microfiltration treatment system and storage tanks.
To clean up contaminated groundwater, extraction wells
and a groundwater collection and transmission system should
be installed so that the groundwater can be pumped to a
central facility where the DuPont/Oberlin system will be
located on-site. Unless the DuPont/Oberlin microfiltration
system is designed for outdoor use, a temporary tent-like
enclosure will be needed to protect the system from inclem-
ent weather. Tanks will likely be required for untreated and
treated groundwater. Drums or other suitable containers will
also be needed to store the filter cake. Also, an equipment
and personnel decontamination facility should be provided,
along with one or more portable chemical toilets or other
suitable sanitary facilities.
Site Access
Site access requirements for the treatment equipment are
minimal. The site must be accessible to tractor-trailer trucks
of standard size and weight. The roadbed must be able to
support such a vehicle delivering the DuPont/Oberlin system
and tanks.
Climate
Below-freezing temperatures and heavy rain could have
an adverse impact on the operation of the DuPont/Oberlin
system. If below-freezing temperatures are expected for a
long period of time, the DuPont/Oberlin system and influent
and effluent storage tanks should be insulated or kept in a
well-heated shelter, such as a building or shed. The DuPont/
Oberlin system should also be protected from heavy rain.
Utilities
The DuPont/Oberlin system requires potable water and
electricity. Potable water is required for preparation of lime
and filter aid slurries, for equipment cleanup, and for personnel
decontamination. In some applications, to conserve water,
filtrate may be used instead of potable water.
The microfiltration unit typically requires 240-volt, 3-
phase, 60-Hz electrical service. Additional electrical power
(110-volt, single phase), is needed mainly for operating the
mixers in the process tanks, lighting the office trailer, and
operating the on-site laboratory and office equipment. Elec-
tricity is also needed to provide heat in the on-site trailer and
equipment shelter area.
A telephone is required to order supplies, contact emer-
gency services, and provide normal communications.
Services and Supplies
A number of services and supplies are required for the
DuPonl/Oberlin microfiltration technology. Most of these
services and supplies can be readily obtained.
In case any of the pumps, mixers, or the air compressor
malfunctions, or if any flow meters or pipelines crack, an
adequate on-site supply of spare parts or access to a nearby
industrial supply center is an important consideration.
An adequate supply of several materials is essential for
the DuPont/Oberlin microfiltration system. These materials
include (1) treatment chemicals (if needed), such as lime, to
12
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adjust pH and precipitate metals, (2) filter aid/cake stabiliz-
ing agent, such as ProFix, and (3) Tyvek® T-980 filter media.
Laboratory facilities to perform analyses, such as metals
and TSS in liquids, and TCLP test and moisture content in
the filter cake, are required to monitor the treatment system's
performance. If such facilities are not available on-site, it
would be prudent to enter into a contract with a local analyti-
cal laboratory for an ongoing monitoring program.
Materials Handling Required by the Technology
Materials handling requirements for the DuPont/Oberlin
microfiltration technology would involve the handling of (1)
pretreatment materials and (2) residuals. These are described
below.
Pretreatment Materials Handling
Pretreatment materials handling requirements for the
DuPont/Oberlin technology depend on the type of waste
being treated. If the technology is applied to remove only
paniculate matter, minimal pretreatment is required. The
pretreatment may involve addition of a filter aid to improve
dewatering characteristics of the waste. However, if the tech-
nology is applied to remove dissolved metals, pretreatment
generally involves metal precipitation (through addition of a
hydroxide, carbonate, or sulfide source) and filter aid addi-
tion. The pretreatment could become more extensive if (1)
the metals need to be oxidized or reduced prior to precipitation
or (2) any metal complexing agents present in the waste
require removal or destruction prior to metal precipitation.
Even if no pretreatment is needed, the liquid wastes may
need to be pumped to an equalization tank to reduce flow
and contaminant concentration fluctuations. The installation
of an equalization tank would also require additional plumb-
ing connections.
Residuals Handling
Two major types of residuals are generated from the
DuPont/Oberlin microfiltration system: (1) treated water
(filtrate) and (2) filter cake.
Filtrate could be disposed of either on- or off-site, once
it meets the applicable regulatory requirements described at
the end of this section. Examples of on-site disposal options
for the filtrate include groundwater recharge and temporary
storage on-site for sanitary use. Examples of off-site disposal
options are discharge into rivers, creeks, storm sewers, and
sanitary sewers. Bioassay tests may be required in addition
to routine chemical and physical analyses before the filtrate
is disposed. The pH of the filtrate may also need to be
adjusted prior to its disposal depending on (1) the pH at
which metal precipitation is done, (2) the filter aid added,
and (3) the disposal site. During the SITE demonstration,
the filtrate met the NPDES permit limits for disposal into a
local waterway for metals and TSS. However, it did not
meet the discharge limit for pH. The treated water pH was
typically 11.5 while the upper discharge limit was 9. The
filtrate pH was higher than the precipitation pH because of
the addition of ProFix (filter aid/cake stabilizing agent).
The filter cake may be landfilled if it passes the paint
filter liquids test. Whether the filter cake can be disposed of
at a nonhazardous landfill depends on its ability to meet the
applicable regulations described in the "Regulatory Require-
ments" section. During the SITE demonstration, the filter
cake was disposed of as a nonhazardous waste. However, at
the DuPont Electronics facility In Sun Valley, California, it
is disposed of as a hazardous waste. DuPont plans to use
ProFix instead of diatomaceous; earth to eliminate off-site
stabilization and reduce operating costs.
The DuPont/Oberlin system also generates spent Tyvek®
filter media, which requires disposal. The spent Tyvek®
media can also be disposed of at either a hazardous or
nonhazardous landfill, depending on whether it meets the
applicable regulations.
Personnel Requirements
Since DuPont/Oberlin's microfiltration unit is automated,
little operator attention is required; one operator per shift
would be adequate. This person should be capable of (1)
preparing pretreatment chemical slurries, such as lime and
filter aid, and adjusting their flow rates to achieve the desired
doses, (2) operating the pneumatic and electronic controls on
the microfiltration unit, (3) collecting solids and liquid samples
and performing simple physical/chemical analyses and mea-
surements (for example, measuring pH, temperature, flow
rate, and TSS), and (4) troubleshooting minor operational
problems. Analytical work requiring higher skills (for ex-
ample, performing metals analysis and the TCLP test) can be
performed by a local laboratory.
Each operator also should have an OSHA-required, ini-
tial 40-hour health and safety training and an annual 8-hour
refresher course before operating DuPont/Oberlin's system at
hazardous waste sites.
Potential Community Exposures
Contaminant exposure from the DuPont/Oberlin
microfiltration system to the community is minimal. When
treating wastes containing volatile contaminants, such as
mercury, proper care should be taken to control the emissions
from the metals precipitation tank. Other types of exposures
include paniculate emissions from lime and filter aid han-
dling and significant noise (estimated to be 80 to 90 decibels)
from the air compressor.
Potential Regulatory Requirements
This subsection discusses specific environmental regula-
tions pertinent to the transport, treatment, storage, and dis-
posal of wastes generated during I he operation of the DuPont/
Oberlin microfiltration system. The regulations that apply to
a particular remediation activity will depend on the type of
remediation site and the type of waste being treated. Table
3-1 provides a summary of regulations discussed in this
subsection.
Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA)
CERCLA, as amended by the Superfund Amendments
and Reauthorization Act (SARA) of 1986, provides for fed-
eral authority to respond to releases of hazardous substances,
pollutants, or contaminants to air, water, and land (Federal
Register, 1990a). Section 121 (Cleanup Standards) of SARA
13
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Table 3-1. Regulations Summary
Act
Applicability
Application To DuPont/Oberlin Microfiltration System
Citation
CERCLA Superfund Sites
The Superfund Program authorizes and regulates the cleanup of environmental
contamination. Applies to all CERCLA site cleanups.
40 CFR Part 300
RCRA
SDWA
CWA
CAA
CERCLA and RCRA Sites
Water Discharges Water
Rcinjcction, and Sole
Source/Wellhead Water
Source!!
Discharges to Surface
Water Bodies
Ambient Air Quality
TSCA
Other
PCB Contamination
Radioactive Wastes
AEAand
RCRA
Mixed Wastes
RCRA defines and regulates the treatment, storage, and disposal of hazardous
wastes.
Maximum contaminant levels and contaminant level goals would be appropriate
standards to consider in setting water cleanup levels at RCRA corrective
action and CERCLA response action sites. (Water cleanup levels are also
discussed under RCRA and CERCLA.) Reinjection of treated water would be
subject to underground injection control program and sole-source and
wellhead water sources to their respective control programs.
NPDES requirements of CWA would apply to both CERCLA and RCRA sites
where treated water is! discharged to surface water bodies.
40 CFR Parts 260-270
40 CFR Part 141
CAA emission standards might apply to fugitive air emissions, if any,
from the DuPont/Oberlin microfiltration system (if the contaminant source and
treatment technology are sufficiently similar to a source and technology
regulated by the CAA). RCRA and CERCLA air emission requirements and any
state programs will be the primary air requirements for use of the DuPont/Oberlin
technology at CERCLA or RCRA sites.
TSCA regulates PCB jspill cleanups. If PCB-containing wastes are treated, TSCA
requirements will generally be appropriate in determining cleanup standards and
disposal requirements,
Agencies regulating the treatment, storage, and disposal of radioactive wastes
include: (1) the EPA, (2) the NRC, (3) the DOE, and (4) the states. Decisions
regarding appropriate'regulations should be based on: (1) the type of radioactive
constituents present and how they were generated; (2) the jurisdiction a site
is under; and (3) requirements that are most protective and appropriate for given
site conditions.
AEA and RCRA requirements apply to the treatment, storage, and disposal of
wastes containing both hazardous and radioactive components. OSWER and DOE
directives provide guidance for addressing mixed wastes.
40 CFR Parts 122-125
40 CFR Parts 50,
60, and 61
40 CFR Part 761
40 CFR Parts 141,440
(water); 10 CFR Parts
20,30, 40, 61,70 (air
and water discharges,
treatment and
disposal, exposure
limits);
40 CFR Part 190
(radiation doses);
40 CFR Part 192
(radon releases,
cleanup standards);
AEA(NRC licensees);
DOE Orders
AEA and RCRA
OSHA
All Remedial Actions
OSHA regulates on-site construction activities and the health and safety of
workers at hazardous waste sites. Implementation and operation of the
DuPont/Oberlin microfiltration system at CERCLA or RCRA sites must
meet OSHA requirements.
29 CFR Parts
1900-1926
29 CFR Part 1910.120
(hazardous waste
operations and
emergency response)
Note: Abbreviations included above are spelled out in this subsection's text
14
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requires that selected remedies be protective of human health
and the environment and be cost-effective. SARA states a
preference for remedies that are highly reliable, provide long-
term protection, and employ treatment that permanently and
significantly reduces the volume, toxicity, or mobility of
hazardous substances, pollutants, or contaminants. The
DuPont/Oberlin microfiltration technology is one such rem-
edy. Section 121 also requires that remedies selected at
Superfund sites comply with federal and state applicable or
relevant and appropriate requirements (ARAR), and it provides
only six conditions under which ARARs for a remedial
action may be waived: (1) the action is an interim measure
and the ARAR will be met at completion, (2) compliance with
the ARAR would pose a greater risk to health and the
environment than noncompliance, (3) it is technically im-
practicable to meet the ARAR, (4) the standard of perfor-
mance of an ARAR can be met by an equivalent method, (5)
a state standard has not been consistently applied elsewhere,
and (6) ARAR compliance would not provide a balance
between the protection achieved at a particular site and de-
mands on the Superfund for other sites. These waiver options
apply only to Superfund actions taken on-site, and justifica-
tion for the waiver must be clearly demonstrated (U.S. EPA,
1988).
Generally, contaminated water treatment using the
DuPont/Oberlin microfiltration system will take place on-
site, while treated water discharge, filter cake disposal, and
filter media disposal may take place either on-site or off-site.
On-site and off-site actions must meet the substantive re-
quirements (for example, emission standards) of all ARARs;
off-site actions must also meet permitting and any other
administrative requirements of environmental regulations.
Resource Conservation and Recovery Act (RCRA)
RCRA regulations define hazardous wastes and regulate
their transport, treatment, storage, and disposal. Wastes de-
fined as hazardous under RCRA include characteristic and
listed wastes.
Criteria for identifying characteristic hazardous wastes
are included in 40 CFR Part 261 Subpart C. Listed wastes
from non-specific and specific industrial sources, off-specifi-
cation products, spill cleanups, and other industrial sources
are itemized in 40 CFR Part 261 Subpart D. For RCRA
regulations to apply, evidence (for example, manifests,
records, and knowledge of processes) must affirm that the
waste is hazardous. Site managers may also test the waste or
use their knowledge of its properties to determine if the
waste is hazardous.
Contaminated water to be treated by the DuPont/Oberlin
microfiltration system will probably be hazardous or suffi-
ciently similar to hazardous waste so that RCRA standards
will be requirements. Because the DuPont/Oberlin
microfiltration system includes waste storage in tanks, 40
CFR Part 265 standards for tank storage (Subpart J) should
be met. Also, RCRA treatment requirements must be met.
Filter cake and spent filter media generated during treat-
ment must be stored and disposed of properly. If the water
treated is a listed waste, treatment residues will be consid-
ered listed wastes (unless RCRA delisting requirements are
met). If the treatment residues are not listed wastes, they
should be tested to determine if they are RCRA characteristic
hazardous wastes. Treatment residues should also be tested
using EPA Method 9095 (paint filter liquids test) to deter-
mine if they contain free liquids. Wastes containing no free
liquids are excluded from various leak detection and second-
ary containment requirements for disposal. Usually, the
DuPont/Oberlin treatment residues will not contain free liq-
uids. If the residuals are not hazardous and do not contain
free liquids, they can be disposed of at a nonhazardous waste
landfill. If the filter cake or filter media is hazardous, the
following RCRA standards apply.
40 CFR Part 262 details istandards for generators of
hazardous waste. These requirements include obtaining an
EPA identification number, meeting waste accumulation
standards, labeling wastes, and keeping appropriate records.
Part 262 allows generators to store wastes up to 90 days
without a permit and without having interim status as a
treatment, storage, and disposal facility. If treatment residues
are stored on-site for 90 days or more, 40 CFR Part 265
requirements apply.
Any facility (on-site or off-site) designated for perma-
nent disposal of hazardous wastes must be in compliance
with RCRA. Disposal facilities must fulfill permitting, stor-
age, maintenance, and closure r<;quirements contained in 40
CFR Parts 264 through 270. In addition, any authorized
state RCRA requirements must be fulfilled. If treatment
residues are disposed off-site, 40 CFR Part 263 transporta-
tion standards apply.
For both CERCLA actions and RCRA corrective ac-
tions, the treatment residuals generated by the DuPont/Oberlin
microfiltration system will be subject to land disposal restric-
tions (LDR) if they are hazardous and land disposed (U.S.
EPA, 1989a). Several LDR compliance alternatives exist for
disposing of the filter cake and spent filter media if they are
hazardous: (1) comply with the LDR that is in effect, (2)
comply with the LDRs by choosing one of the LDR compli-
ance alternatives (for example, itreatability variance, no mi-
gration petition), or (3) invoke am ARAR waiver (this option
would only apply to on-site CERCLA disposal).
40 CFR Part 264, Subparts F (promulgated) and S (pro-
posed) include requirements for corrective action at RCRA-
regulated facilities. In addition, these subparts generally
apply to remediation at Superfund sites. Subparts F and S
include requirements for initiating and conducting RCRA
corrective actions, remediating groundwater, and ensuring
that corrective actions comply with other environmental
regulations. Subpart S also details conditions under which
particular RCRA requirements may be waived for temporary
treatment units operating at connective action sites (Federal
Register, 1990b).
Clean Water Act (CWA)
The NPDES permitting program established under the
CWA issues, monitors, and enforces permits for direct dis-
charges to surface water bodies. Discharges to off-site re-
ceiving waters or to publicly owned treatment works (POTW)
must comply with applicable federal, state, and local admin-
istrative and substantive requirements. Effluent limits are
15
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contained in the NPDES permit issued for direct discharges
to off-site receiving waters. No NPDES permits are issued
for on-site discharges or off-site discharges to POTWs, but
all substantive requirements (such as discharge limits) should
be identified and achieved.
Safe Drinking Water Act (SDWA)
The SDWA, as amended in 1986, includes the following
programs: (1) drinking water standards, (2) underground
injection control (UIQ program, and (3) sole-source aquifer
and wellhead protection programs. ,
SDWA drinking water primary (health-based) and sec-
ondary (aesthetic) maximum contaminant levels will gener-
ally be appropriate cleanup standards for water that is, or
may be, used as a source of drinking water. In some cases,
alternate concentration limits will be appropriate (for ex-
ample, in cases where multiple contaminants are present).
Decision makers should refer to CERCLA and RCRA stan-
dards for guidance in establishing alternate concentration
limits.
Water discharge through injection wells is regulated
under the UIC program. This program categorizes injection
wells as Classes I through V, depending on their construction
and use. Reinjection of treated water involves Class IV
(reinjection) or Class V (recharge) wells and should meet {the
appropriate requirements for well construction, operation,
and closure.
The sole-source aquifer protection and wellhead protec-
tion programs are designed to protect specific drinking water
supply sources. If such a source is to be remediated, appro-
priate program officials should be notified, and any potential
problems should be identified before treatment begins.
Clean Air Act (CAA)
Pursuant to the CAA, EPA has set national ambient air
quality and pollutant emissions standards. CAA require-
ments will generally not apply to the DuPont/Oberlin
microfiltration system, although they may apply on a source-
specific basis (see radioactive waste regulations discussion).
However, air emissions should be monitored to ensure that
they comply with CAA standards.
RCRA air standards generally must be met for CERCLA
response actions and RCRA corrective actions. Forthcorning
RCRA regulations (40 CFR Part 269) will address air emis-
sions from hazardous waste treatment, storage, and disposal
facilities. When promulgated, these requirements will include
air emission standards for equipment leaks and process vents,
a category that will cover any fugitive air emissions frohi a
DuPont/Oberlin microfiltration system. In addition, states'
programs to regulate toxic air pollutants, when established,
will be the most significant regulations for environmental
remediation activities. Generally, air emissions from i the
DuPont/Oberlin microfiltration system will be minimal, and
complying with air emission regulations should not be a
problem. To minimize air emissions, however, pretreatment
might be required for water containing volatile organic con-
taminants.
Toxic Substances Control Act (TSCA)
The DuPont/Oberlin microfiltration system has the capa-
bility to handle wastes containing polychlorinated biphenyls
(PCB), although PCBs are not removed by the system. TSCA
requirements set standards for PCB spill cleanups and PCB
disposal which should be achieved if PCB waste is treated.
The EPA document CERCLA Compliance with Other Laws
Manual, Part II: Clean Air Act and Other Environmental
Statutes and State Requirements discusses TSCA as it per-
tains to Superfund actions (U.S. EPA, 1989b). The proposed
RCRA corrective action regulations (Federal Register, July
1990) state that PCB waste should be handled in accordance
with TSCA PCB spill cleanup policy. As TSCA does not
regulate direct spills to surface water or drinking water,
cleanup standards for these sites are established by EPA
regional offices.
Radioactive Waste Regulations
The DuPont/Oberlin microfiltration system has the capa-
bility to treat water contaminated with radioactive materials.
Decisions concerning what is an appropriate requirement for
a site contaminated with radioactive waste should be based
on the following factors: (1) what type of radioactive con-
stituents are present and how they contaminate the site, (2)
whose regulatory jurisdiction the site falls under, and (3)
which regulation is most protective or appropriate. The
primary agencies that regulate the cleanup of radioactively
contaminated sites are EPA, the Nuclear Regulatory Com-
mission (NRC), the Department of Energy (DOE), and the
states. In addition, nongovernmental agencies may issue
advisories or guidance, which should also be considered in
developing a protective remedy.
The SDWA has established maximum contaminant lev-
els for radionuclides in community water as a concentration
limit for alpha-emitting radionuclides and as an annual dose
limit for the ingestion of beta/gamma-emitting radionuclides.
These standards are appropriate in setting cleanup standards
for radioactively contaminated water. Discharge of treated
water from radioactively contaminated sites could be subject
to 40 CFR Part 440 Subpart C, which establishes radionuclide
concentration limits for liquid effluent from facilities that
extract and process uranium, radium, and vanadium ores.
The DuPont/Oberlin microfiltration system has the potential
to treat water to well within the radioactivity limits established
by these regulations. However, treated water should be tested
to ensure that such limits are not being exceeded.
Any fugitive radioactive air emissions that result from
the DuPont/Oberlin microfiltration system must achieve ra-
dionuclide emissions standards promulgated under the CAA
(codified in 40 CFR Part 61).
The Environmental Radiation Protection Standards (40
CFR Part 190) promulgated under the authority of the Atomic
Energy Act (AEA) set standards for radiation doses to the
general public caused by normal operations within the uranium
fuel cycle. These requirements should be considered at sites
where such contamination is being treated or disposed.
Standards regulating the stabilization, control, and disposal
of uranium and thorium mill tailings are included in 40 CFR
Part 192. These regulations set cleanup, control, and release
16
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standards for radioactive materials.
NRC regulations cover the possession and use of source,
by-product, and special nuclear materials by NRC licensees.
These regulations apply to sites where radioactive contami-
nation exists. 10 CFR Parts 20, 30, 40, 61, and 70 cover
protection of workers and the public from radiation, dis-
charges of radionuclides to air and water, and waste treat-
ment and disposal requirements for radioactive waste. The
filter cake and spent filter media generated by microfiltration
of radioactive water might be regulated under these parts if
they contain residual radioactivity.
DOE requirements are included in a series of internal
DOE orders that have the same force as regulations at DOE
facilities. These DOE directives should be considered when
developing protective remedies at CERCLA sites or RCRA
corrective action sites, although they apply directly only to
DOE sites. DOE orders address exposure limits for the
public, concentrations of residual radioactivity in soil and
water, and management of radioactive wastes (U.S. DOE,
1988).
Mixed Waste Regulations
Use of the DuPont/Oberlin microfiltration system at sites
with radioactive contamination might involve the treatment
or generation of mixed waste. Mixed waste contains both
radioactive and hazardous components (as defined by the
AEA and RCRA) and is subject to the requirements of both
acts. When the application of both regulations results in a
situation that is inconsistent with the AEA (for example, an
increased likelihood of radioactive exposure), AEA require-
ments supersede RCRA requirements.
EPA's Office of Solid Waste and Emergency Response
(OSWER), in conjunction with the NRC, has issued several
directives to assist in the identification, treatment, and dis-
posal of low-level radioactive mixed waste. Various OSWER
directives include guidance on defining, identifying, and dis-
posing of commercial mixed low-level radioactive and haz-
ardous waste (U.S. EPA, 1987). If the DuPont/Oberlin
microfiltration system is used to ireat low-level mixed wastes,
these directives should be considered. If high-level mixed
waste or transuranic mixed waste is treated, DOE internal
orders should be considered when developing a protective
remedy (U.S. DOE, 1988).
Occupational Safety and Healtlli Act (OSHA)
CERCLA response actions and RCRA corrective actions
must be performed in accordance with OSHA requirements
detailed in 29 CFR Parts 1900 through 1926, especially Part
1910.120, which provides for the health and safety of work-
ers at hazardous waste sites. Ora-site construction activities
at Superfund or RCRA corrective action sites must be per-
formed in accordance with Part 1926 of OSHA (Safety and
Health Regulations for Construction). For example, con-
struction of electric utility hookups for the DuPont/Oberlin
microfiltration system would need to comply with Part 1926,
Subpart K (Electrical). Also, any more stringent state re-
quirements would need to be met.
17
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Section 4
Economic Analysis
The costs associated with the DuPont/Oberlin
microfiltration technology have been placed into the 12 cost
categories that are applicable to typical cleanup activities at
Superfund and Resource Conservation and Recovery Act
(RCRA) corrective action sites (Evans, 1990). These cost
categories are defined and discussed in this section as they
apply to the DuPont/Oberlin microfiltration technology,
thereby forming the basis for the estimated costs presented in
Table 4-1. The annual operating and maintenance costs, as
well as one-time costs presented in Table 4-1, are for two
microfiltration systems with filtration areas of 2.4 square feet
(demonstration unit) and 36 square feet (largest unit avail-
able). The costs presented in this analysis are order-of-magni-
tude (-30 to +50 percent) estimates, as defined by the Ameri-
can Association of Cost Engineers (Humphreys, 1984).
Site-Specific Factors Affecting Cost
A number of factors affect the estimated cost of a DuPont/
Oberlin microfiltration system. These factors are highly site-
specific and rather difficult to identify if accurate site loca-
tion and site data are unavailable. The factors that will affect
the cost generally include: volume of groundwater or other
type of liquid waste to be treated; type and concentration of
contaminants in the water; physical site conditions (such as
site access and availability of utilities); required support fa-
cilities, extraction wells for contaminated groundwater, auxil-
iary equipment, and buildings; geographical location (avail-
ability of supplies and consumables, availability of service
for equipment); treatment goals to be met; discharge permit
requirements; and frequency of equipment repair and re-
placement.
Basis of Economic Analysis
The DuPont/Oberlin technology can be applied to treat
several types of liquid wastes including contaminated
groundwater, landfill leachate, and industrial wastewater. For
the purpose of this economic analysis, contaminated ground-
water was selected as the liquid waste since it represents (1) a
waste commonly found at Superfund and RCRA corrective
action sites and (2) a waste treatment scenario that covers
several cost categories. It should be noted that all the catego-
ries for the contaminated groundwater scenario may not ap-
ply to other types of liquid waste. Therefore, when estimating
the costs for a given scenario, only applicable categories
should be used.
For the purpose of this economic analysis, it is assumed
that a DuPont/Oberlin microfiltration system will treat con-
taminated groundwater on a batch cycle, 24 hours per day, 7
days per week for 1 year. The average time of each cycle is
assumed to be 20 minutes. The ratal volume of groundwater
treated during each cycle is difficult to estimate since it
depends on the (1) concentration of the contaminants of
concern in the groundwater, (2) amount of filter aid used,
and (3) size of the microfiltration unit During the technol-
ogy demonstration, a 2.4-square foot microfiltration unit
treated approximately 20 gallons of groundwater during each
cycle. Therefore, it is assumed that the 36-square foot
microfiltration unit will be capable of treating 300 gallons of
groundwater during each cycle.
During a 1-year period, the 2.4-square foot unit will treat
approximately 525,600 gallons, and the 36-square foot unit
will treat approximately 7,884,0()0 gallons. A 1-year period
of time was chosen for this analysis so that an estimated
annual operation and maintenance cost could be developed.
It should be noted, however, that most groundwater remedial
actions cover a significantly longer period of time (such as
10 to 30 years) and may require multiple treatment units.
For this analysis, the following assumptions were made
regarding the untreated groundwater, operating conditions,
and filtrate. The groundwater is acidic (has a pH of less than
7), has negligible ligands and organic contaminants, and is
primarily contaminated with heavy metals (such as lead or
zinc) at levels of up to 500 mg/L. The microfiltration system
operating conditions are as follows: a precipitation pH of 9
(a lime dose of 1.5 g/L to raise the pH from 4.7); a filter aid
dose of 12 g/L; a blowdown time of 0.5 minute; and a
blowdown pressure of 38 psig. The contaminated groundwa-
ter will be treated to meet National Pollutant Discharge
Elimination System (NPDES) requirements for discharge into
a nearby surface water.
The following is a list of other assumptions used for this
analysis:
The site is located in the Midwest.
Utilities such as electricity and telephone lines
will be overhead.
Suitable access roads are available.
Contaminated groundv/ater is in a shallow
aquifer.
A heated temporary tent-like enclosure will be
required to house equipment.
The installation cost of the microfiltration system
at the site is assumed to be 3 to 5 percent of the
capital equipment cost (depending on size) and
is included in the capital cost.
One technician will be: required per shift to
operate and maintain the equipment, collect all
required samples, and perform equipment
maintenance and minor repairs.
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Table 4-1. Estimated Costs Associated with DuPont/Oberlin Microfiltration Systems
Cost Categories
Estimated Costs (1990 $)
2.4 sq. ft." 36 sq.ft.8
Site Preparation b
Permitting and Regulatoryb
Capital Equipment11
Startup and Fixed b
Labor6
Supply and Consumable0
Utility °
Effluent Monitoring0
Residuals and Waste Shipping, Handling, and
Transporting0
Analytical0
Equipment Repair and Replacement c
Site Demobilization15
209,200
2,300
47,800
80,000
133,400
16,900
5,500
15,000
3,700
36,000
2,500
30,000
843,200
11,200
231,800
80,000
133,400
220,000
82,500
15,000
55,200
36,000
7,000
85,000
Total One-Time Costs
Total Annual Operation and Maintenance Costs
369,300 1,251,200
213,000 549,100
Notes:
During a one-year period, it is assumed that the 2.4-sq. ft. unit will treat
aboutS25,600 gallons and the 36-sq. ft. unit will treat about 7,884,000
gallons.
One-time costs.
Annual operation and maintenance costs.
Labor costs associated with major equipment
repairs or replacement are not included.
The filter cake and used filter media will be
considered nonhazardous wastes, and will be
disposed of in a permitted sanitary landfill.
A composite sample will be taken weekly from
the filtrate discharge and analyzed for heavy
metals and pH.
Filter aid will be purchased in sacks for the
2.4-square foot unit and in bulk for the 36-
square foot unit.
No pretreatment other than lime addition and
filter aid addition is required.
The filtrate will require pH adjustment (post-
treatment) to meet applicable discharge limits
(typically 6 to 9).
Site demobilization does not include
transportation of the microfiltration equipment.
A discussion of each of the 12 cost categories and the
elements associated with each category is provided in
Table 4-1.
Site Preparation Costs
The costs associated with site preparation include plan-
ning and management, system design (as well as design of
auxiliary systems and controls), legal searches, access rights,
construction work, emergency and safety equipment, shake-
down, and start-up.
Site preparation costs will vary depending on the type,
condition, and geographical location of the site. Sites that
require major clearing or sites that are located in the northern
part of the country will have significantly increased site
preparation cost. Utilities must be installed in accordance
with national codes and local ordinances.
20
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In addition to the above items, site preparation costs
include an untreated groundwater storage tank, an office/
laboratory trailer, an air compressor, a temporary tent-like
structure for the microfiltration system, a pH adjustment
system, and treated groundwater discharge piping.
For this analysis, site preparation costs are estimated to
be approximately $209,200 for the 2.4-square foot
microfiltration unit and $843,200 for the 36-square foot
microfiltration unit (R.S. Means Co. Inc., 1989; McArdle, et
al, 1988). Installation of a groundwater extraction and trans-
mission system, which was not included in this analysis, may
considerably increase the site preparation cost. The cost for
this system was not estimated because it is highly site-spe-
cific.
Permitting and Regulatory Costs
Permitting and regulatory costs will vary depending on
whether treatment is performed on a Superfund or a RCRA
corrective action site and on how the effluent, filter cake, and
filtrate are disposed. Section 121 (d) of the Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA), as amended by the Superfund Amendments and
Reauthorization Act (SARA), requires that remedial actions
be consistent with applicable or relevant and appropriate
requirements (ARAR) of environmental laws, ordinances,
regulations, and statutes. ARARs include federal standards
and criteria, as well as more stringent standards or criteria
promulgated under state or local jurisdictions, and must be
determined on a site-specific basis.
At RCRA corrective action sites, analytical protocols
and annual monitoring records will have to be kept, which
will increase the regulatory costs. For these situations, an
additional 5 percent should be added to the cost estimated for
this category. Contaminated soil removed during the installa-
tion of monitoring and extraction wells will have to be disposed
of in compliance with RCRA or state requirements. Soil that
will be disposed of at a permitted landfill will have to meet
federal or state land disposal restriction requirements.
Permitting and regulatory costs are assumed to be ap-
proximately 5 percent of the capital equipment costs for a
treatment operation that is part of a Superfund remedial
action.
Capital Equipment Costs
Capital equipment costs include the cost of the
microfiltration system and the required auxiliary equipment,
as well as the installation cost. Based on information pro-
vided by Oberlin, these costs are $45,500 for the 2.4-square
foot unit and $225,000 for the 36-square foot unit. Installa-
tion costs are assumed to be approximately 3 to 5 percent of
the capital cost (depending on size). The total capital cost is,
therefore, estimated to be $47,800 for the 2.4-square foot unit
and $231,800 for the 36-square foot unit. These costs include
only the equipment furnished by the microfiltration system
manufacturer.
Startup and Fixed Costs
Startup costs include those costs required to establish
operating procedures, train operators, perform initial shake-
down of equipment and analysis procedures, and initiate an
environmental monitoring program.
To ensure safe, economical, and efficient operation of
the system, an operator training program will be required.
The costs associated with developing the operator training
program will include developing a health and safety program
and associated documents, providing health and safety train-
ing, and providing operation and maintenance training for
the microfiltration system.
All new operators will need health and safety training.
In addition, since all operators will be responsible for daily
monitoring and operation of the equipment, operation and
maintenance training will be required and will be provided
by equipment manufacturers and the engineer responsible for
designing the system. Startup training costs are estimated to
be approximately $30,000. This estimate is based on four
40-hour health and safety training courses, 4 weeks of opera-
tion and maintenance training (including "hands-on"), and
one week follow-up training for equipment troubleshooting.
Mobilization and shakedown costs include transporta-
tion of the equipment to the site, initial setup, initial startup
and trial runs, and equipment optimization. These costs are
site-specific and will vary depending on the location of the
site, complexity of controls, and the degree of automation.
For this analysis, mobilization, shakedown, and equipment
startup are assumed to be $50,000. Total startup and fixed
costs are estimated to be approximately $80,000.
Labor Costs
After the construction, equipment installation, initial
startup, and optimization are completed, the operators will
assume operation of the system. The system will operate on a
batch cycle, with an operator monitoring operation of all
auxiliary equipment and making necessary adjustments to
compensate for changes in metal concentration, pH, and
temperature of the groundwater. The operator will also
prepare the required chemicals, such as lime slurry for pH
adjustment and filter aid, and will collect the required samples,
dispose of filter cake, and operate auxiliary equipment. This
analysis assumes that four operators will operate this system
on a shift basis 7 days per week, 24 hours per day. It is
assumed that the operators will Ije paid $15 per hour (fringe
benefits are not included). The annual operating labor cost
will be $131,400 for the operators. All operators will require
an annual health and safety refresher course, which is esti-
mated to cost $2,000 annually. Total annual labor costs are
estimated to be $133,400.
Supply and Consumable Costs
Supplies and consumable costs for the DuPont/Oberlin
microfiltration system include filter aid, lime for pH control,
filter media, hydrochloric acid for effluent pH adjustment,
and other miscellaneous supplies. The quantities of filter
aid, lime, filter media, and hydrochloric acid used will de-
pend on the size of the system and the concentrations of the
metallic contaminants in the groundwater. These costs are
21
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estimated to be approximately $16,900 for the 2.4-square
foot unit and $220,000 for the 36-square foot unit. Except
for hydrochloric acid, costs are based on the average cost of
supplies and consumables incurred during the SITE demon-
stration of the DuPont/Oberlin system. Hydrochloric acid
costs are estimated based on lowering the filtrate (effluent)
pH from 11.5 to between 6 and 9.
Utility Costs
The DuPont/Oberlin system operates on 240/480V three-
phase electric power. In addition to electric power, the
system requires high pressure air at approximately 100 psig.
Since the air compressor is driven by an electric motor, only
total electric power requirements will be evaluated. The
system also requires potable water at 40 psig for equipment
washing and preparation of lime and filter aid slurries. About
150 gallons of potable water should be adequate per 1,000
gallons of water treated. In some applications, to conserve
water filtrate may be used instead of potable water.
The total electric power requirements will greatly de-
pend on the total quantity of groundwater treated as well; as
the size of the microfiltration unit used, the size of the
compressor used, and the size of all auxiliary equipment,
which is also electrically driven. It is estimated that the
electric power cost will be approximately $8.46 per 1,000
gallons treated. For this analysis, it is assumed that the
power cost is $.10 per kilowatt-hour. It should be noted that
the cost of power can vary by as much as 50 percent,
depending on the local utility company rates.
The cost of water required is estimated to be about $2,00
per 1,000 gallons treated. It should be noted that this cost
can vary by as much as 1,000 percent depending on geo-
graphic location, availability of water, distance to the nearest
water main, and other factors. If water is to be delivered by
truck, this cost will be higher yet.
The cost of heating and ventilation of the required tent-
like enclosure for the microfiltration equipment and office/
laboratory space is not included in this analysis. This cost
will greatly depend on geographic location, availability of
natural gas (cost of electric heat is much higher), and many
other factors.
Effluent Monitoring Costs
This cost category covers effluent monitoring for com-
pliance with NPDES permit limits. Effluent monitoring will
be performed by the microfiltration system operators. Efflu-
ent will be discharged to a nearby surface water or reinjected
into the groundwater if permitted by local and state regula-
tions. The cost estimate for effluent monitoring will greatly
depend on local and state requirements. For this analysis, it
is assumed that the effluent will be discharged to a nearby
surface water by gravity, and the cost associated with moni-
toring is $15,000 per year.
Residuals and Waste Shipping, Handling, and
Transportation Costs
The DuPont/Oberlin microfiltration system produces
considerable amount of filter cake, which requires special
handling and disposal. Used filter media also needs to be
disposed of. For this analysis, all these materials are assumed
to be nonhazardous and, therefore, may be disposed of in a
permitted sanitary landfill. These costs will depend on geo-
graphic location, distance to the permitted landfill from the
site, as well as other factors such as the concentrations of
regulated metallic contaminants in the groundwater, the de-
gree of treatment, and the quantity of filter aid used.
Waste shipping, handling, and transportation costs are
based on the generation of 70 pounds of filter cake per 1,000
gallons of groundwater treated and an estimated disposal cost
of $200 per ton. The annual handling, shipping, and disposal
costs are estimated to be $3,700 for the 2.4-square foot unit
and $55,200 for the 36-square foot unit.
Analytical Costs
Analytical costs include sample shipment, laboratory
analysis, data reduction and tabulation, quality assurance and
quality control (QA/QC), and reporting. Monthly laboratory
analysis costs are estimated to be approximately $2,000,
while data reduction and tabulation, QA/QC, and reporting
should cost approximately $1,000 per month. This analysis
assumes that four treated water samples will be taken every
month and analyzed for metals. Total estimated analytical
costs, therefore, are approximately $36,000 per year.
Equipment Repair and Replacement Costs
During the course of operation, some parts of the system
may require repair or replacement Since insufficient data is
available on the long-term reliability of a microfiltration
system, no cost can be assigned. For this analysis, it is
assumed that the annual equipment repair and replacement
cost is $2,500 for the 2.4-square foot microfiltration unit
system and $7,000 for the 36-square foot unit system. This
cost, however, does not include any major repairs or replace-
ments.
Site Demobilization Costs
Site demobilization will include operation shutdown and
decommissioning of equipment, site cleanup and restoration,
disconnection of utilities, closing of groundwater extraction
wells, and disposal of decontamination waste and any other
wastes. Site demobilization costs will vary depending on
whether the treatment operation was conducted at a Superfund
site or at a RCRA corrective action site. Demobilization at a
RCRA corrective action site will require detailed closure
plans and permits, which are not required at a Superfund site.
This analysis assumes site demobilization costs will only
cover costs of disassembling and transporting all equipment
and removing all exposed piping and electrical lines. This
estimated cost is based on previous similar projects. The
estimated demobilization cost for the 2.4-square foot unit is
$30,000 and $85,000 for the 36-square foot unit. Decommis-
sioning and disposal of buildings, permanent tanks, and ex-
traction/monitoring wells is not included in this cost esti-
mate.
22
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References
Evans, G., 1990. Estimating Innovative Technology Costs
for the SITE Program, Journal of Air andWaste Man-
agement Association, 40:7 1047-
1051.
Federal Register, 1990a. National Oil and Hazardous
Substances Contingency Plan; Final Rule, Volume 55,
No. 46, March 8.
Federal Register, 1990b. Proposed Rules for Corrective
Action for Solid Waste Management Units at Hazardous
Waste Management Facilities, Volume 55, No. 145,
My 27.
Humphreys, K.K., 1984. Project and Cost Engineers'
Handbook, 2nd Edition. Marcel Dekker, New York, New
York.
Karassik, I.J., 1986. Pump Handbook, 2nd Edition, McGraw-
Hill Book Company, New York, New York.
McArdle, J.L., et al, 1988. "Leachate Treatment Unit
Processes- -Physical/Chemical Treatment Operations,
Neutralization," Treatment of Hazardous Waste
Leachate—Unit Operations and Costs, Pollution
Technology Review No. 151, Noyes Data Corporation,
Park Ridge, New Jersey.
Oberlin, 1984. Oberlin Pressure Filter Instruction &
Maintenance Manual, Oberlin Filter Company,
Waukesha, Wisconsin.
R.S. Means Co. Inc., 1989. Means Construction Cost Data,
47th Annual Edition. Construction Consultants and
Publishers, Kingston, Massachusetts.
U.S. DOE, 1988. Radioactive Waste Management Order,
DOE Order 5820.2A, September 26.
U.S. EPA, 1982. Process Design Manual for Dewatering
Municipal Wastewater Sludges, EPA/625/1-82/014,
Cincinnati, Ohio.
U.S. EPA, 1987. Joint EPA/NRC Guidance on Mixed Low-
Level Radioactive and Hasiardous Waste: OSWER
Directives 9480.00-14, June 29; 9432.00-2, January 8;
and 9487.00-8 August 3.
U.S. EPA, 1988. CERCLA Compliance with Other Laws
Manual (Interim Final), OSWER, EPA/540/G-89/006.
U.S. EPA, 1989a. Superfund LDR Guide #1, Overview of
RCRA Land Disposal Restrictions (LDRs), U.S. EPA
Directive 9346.3-01FS.
U.S. EPA, 1989b. CERCLA Compliance with Other Laws
Manual: Part II. Clean Air Ac land Other Environmental
Statutes and State Requirements, (Interim Final), OSWER
Directive 9234.1-02.
WPCF, 1984. Prime Movers: Engines, Motors, Turbines,
Pumps, Blowers & Generators, Manual of Practice OM-
5, Water Pollution Control Federation, Washington, D.C.
23
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Appendix A
Vendor's Claims for the Technology
Introduction
Many industries face the challenge of removing heavy
metals from groundwaters and industrial wastewaters to meet
stringent discharge or disposal limits. Conventional technolo-
gies, such as chemical precipitation followed by clarification
and sand filtration, are generally unsuitable to meet the strin-
gent limits, while advanced technologies such as ion ex-
change, ultrafiltration, and reverse osmosis are expensive
options for heavy metal removal. The metals precipitate gen-
erated during the chemical precipitation process is usually
landfilled. However, the Resource Conservation and Recov-
ery Act (RCRA) requires that the precipitate pass the paint
filter liquids test before it can be landfilled. RCRA also
requires that the precipitate pass the toxicity characteristic
leaching procedure (TCLP) test for its disposal at a
nonhazardous waste landfill. For these reasons, the metals
precipitate must be adequately dewatered (to pass the paint
filter liquids test) and stabilized (to pass the TCLP test).
The DuPont/Oberlin microfiltration technology can treat
metal-bearing wastewaters to meet regulatory requirements at
a reasonable cost. The use of this technology has solved
many problems found in the metal forming and metal work-
ing industries, eliminating many disadvantages of conven-
tional treatment technologies, particularly chemical precipi-
tation followed by clarification and sand filtration. A descrip-
tion of the DuPont/Oberlin microfiltration technology and its
applications are presented below.
DuPont/Oberlin Microfiltration Technology
The DuPont/Oberlin microfiltration technology is a
physical separation process for removing submicron particles
from liquid wastes. The submicron particles from liquid wastes
are removed using a spunbonded olefin filter media, known
as Tyvek® T-980 (developed by E.I. DuPont de Nemours and
Company, Inc.), and an automatic pressure filter (developed
by Oberlin Filter Company). The Tyvek® filter media has a
high tensile strength (wet and dry) and is manufactured and
sold in rolls, making it suitable for use with the Oberlin filter,
which uses a roll feed and discharge. Another important
feature of the Tyvek® media is its smooth and slick surface
which facilitates excellent separation of filtered solids from
its surface. Tyvek® can remove submicron particles at a cost
almost 97.5 percent less than other competitive filtration
media, such as microporous membranes (Lim and Mayer,
1989).
When liquid wastes contain dissolved metals, DuPont/
Oberlin pretreats the wastes to convert the metals into an
insoluble form (precipitate) using chemicals, such as lime,
caustic, sodium carbonate, or sodium sulfide. After the
metals are precipitated, a filter slid/stabilizing agent, known
as ProFix (manufactured by EnviroGuard, Inc. of Houston,
Texas), is added to the metals precipitate prior to
microfiltration to produce a dry and stabilized filter cake.
A brief description of the Oberlin pressure filter and its
capabilities are presented below.
Oberlin Pressure Filter Equipment
The Oberlin pressure filter is a versatile, rugged, and
industrial-scale solid/liquid separation unit. A schematic of
the Oberlin pressure filter is shown in Figure 2-1. The filter
has two compartments—an upper compartment, or filter
platen; and a lower compartment, or filter chamber. The
platen moves while the chamber is fixed in place. The filter
media lies between these two compartments.
At the beginning of a filtration cycle, airbags lower the
filter platen against the filter chamber. Platen seals on the
perimeter of the compartments fomi a liquid-tight seal around
the filter media. The liquid waste containing solids is pumped
into the platen and forced by the pump pressure through the
filter media. The filtered liquid is collected in the lower
compartment and drained out.
When the pressure inside the filter reaches 30-50 psig
(maximum, depending on the model), the feed pumping
stops, and pressurized air is fed into the platen forcing the
remaining liquid through the filter cake and media. After the
cake is dried (as determined by back pressure and time
elapsed), the platen is lifted by an air cylinder. The cake is
then automatically discharged either by using an endless
conveyor belt or by simply pulling the spent filter media by a
motor driven reroller. After the cake discharge, the filter
platen automatically descends zmd a new filtration cycle
starts.
The filter is made of carbon steel. All parts can be lined
with 304/316 stainless steel or coated with Halar or other
metals such as Alloy 20, if required. The filter does not
require a special foundation; a flat area is adequate. Electri-
cal controls are based on either discrete relays and timers or
programmable logic controllers (PLC). Filters with explosion
proofing option (for treating munitions wastes) are also
available.
Oberlin Pressure Filter Capabilities
The Oberlin pressure filter has a few unique capabilities
to produce a high quality filtrate and a dry cake while
treating liquid wastes. These capabilities are listed below:
25
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It operates at a relatively high pressure (up to
50 psig) to ensure long operating cycles.
• It is truly an automatic filtration system designed
for unattended operation (except for filter aid
slurry preparation, cake removal, and filter media
roll replacement). Its operation is precisely
controlled through a PLC to minimize operator
attention.
It has a horizontal filtering area to allow
relatively thick filter cake to form. Also, the
cake formed in this process is dry because the
moisture present in the cake is forced out by
pressurized air or nitrogen.
• The filter is skid-mounted for easy
transportation.
• The operating costs are kept low through the
use of standard industrial controls for the filter.
Applications of the DuPont/OberlinMicrofiltration
Technology
The DuPont/Oberlin microfiltration technology has been
used to:
• Treat wastewater containing uranium, aluminum,
lead, cadmium, nickel, copper, and zinc to meet
fairly stringent National Pollutant Discharge
Elimination System limits at metal forming
operations in uranium manufacturing processes.
• Treat lead-bearing wastewaters from a ceramics
manufacturing plant.
• Remove heavy metals from a battery
manufacturing facility's wastewater.
• Remove lead solids from an electronics
manufacturing plant's wastewater.
Remove lead from a munitions plant's
wastewater.
• Remove copper, zinc, cadmium, and lead from
another munitions plant's wastewater.
• Remove iron, lead, chromium, nickel, copper,
and zinc from contaminated groundwater prior
to volatile organic compounds removal by
stripping, !
• Remove iron, lead, chromium, copper, zinc,
silver, and nickel from a chemical plant's
wastewater prior to discharge. Discharge limits
are very low for this application (for example,
13 ppb for copper).
Details on some of these applications can be found in a
paper presented at the Second U.S. EPA Forum on Innova-
tive Hazardous Waste Treatment Technologies, Philadelphia,
Pennsylvania (Mayer, 1990). As can be seen from these
applications, the technology is well suited for a variety of
wastewaters and groundwaters, if the metals can be con-
verted into an insoluble form prior to filtration.
Summary
Over the past 8 years, the DuPont/Oberlin microfiltration
technology has evolved into a viable technique for removing
heavy metals from contaminated groundwaters and industrial
wastewaters. It is basically a submicron filtration process
that removes practically all suspended metals much more
effectively than conventional techniques (such as precipitation
followed by clarification, and sand filtration). It also pro-
duces a dry cake that will pass the paint filter liquids test and
the TCLP test. It accomplishes this in a simple, one-step
operation that is totally automatic except for media replace-
ment, filter aid makeup, and cake removal. Systems are now
available that can also automate these steps, if desired.
References
Lim, H.S., and E. Mayer, 1989. Tyvek for Microfiltration
Media, Fluid Particle Separation Journal, 2:1:17-21.
Mayer, E., 1990. DuPont/Oberlin Microfiltration System for
Hazardous Wastewaters, presented at the Second U.S.
EPA Forum on Innovative Hazardous Waste Treatment
Technologies: Domestic and International, Philadelphia,
Pennsylvania.
26
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Appendix B
SITE Demonstration Results
Introduction
In February 1988, E.I. DuPont de Nemours and Com-
pany, Inc. (DuPont) and Oberlin Filter Company (Oberlin)
submitted a joint proposal for their microfiltration technol-
ogy to U.S. Environmental Protection Agency's (EPA) Of-
fice of Research and Development (ORD) and Office of
Solid Waste and Emergency Response (OSWER) under the
Superfund Innovative Technology Evaluation (SITE) pro-
gram. EPA selected the DuPonl/Oberlin microfiltration tech-
nology and identified the Palmerton Zinc Superfund (PZS)
site as an appropriate site for the technology demonstration.
The technology was demonstrated at the PZS site in April
and May 1990 through a cooperative effort between ORD,
OSWER, EPA Region 3, DuPont, and Oberlin. This appen-
dix briefly describes the PZS site and summarizes the SITE
demonstration activities and demonstration results.
Site Description
The site is located in the Lehigh Valley along the
Aquashicola Creek in the town of Palmerton, Pennsylvania.
Figure B-l is a map of the site. The site includes all areas of
possible contamination resulting from operations at the Zinc
Corporation of America (ZCA) industrial complex. The ZCA
complex consists of two zinc smelting plants. West of the
town is the West Plant, located where the Lehigh River
meets the Aquashicola Creek. The East Plant is located on
the southern bank of the Aquashicola Creek.
Zinc smelting operations at the PZS site began in 1898
and 1915 at the West and East Plants, respectively. In 1980,
primary zinc smelting at the ZCA facility ceased and the
West Plant was shut down. Secondary metal refining and
processing operations continue in the East Plant.
During the last 70 years, zinc smelter operations have
resulted in 33 million tons of zinc residue accumulating and
forming an extensive cinder bank along the southern bound-
ary of the East Plant. This cinder bank has contaminated the
surrounding areas, including the groundwater and surface
water. Because of the contamination, the cinder bank was
placed on the National Priorities List (NPL No. 339) in
December 1982. Under an Administrative Order of Consent
dated September 24, 1985, ZCA agreed to conduct a reme-
dial investigation/feasibility study (Rl/FS) of the on-site sur-
face water and groundwater, as well as the cinder bank. The
RI/FS work was carried out by ZCA's contractor, R.E. Wright
Associates, Inc.
Site Contamination Characteristics
Air emissions from smelting operations at the East and
West Plants, and the cinder bank, have contaminated the
surrounding environment. The primary constituents of con-
cern are cadmium, copper, lead, and zinc. Cadmium, copper,
and lead commonly occur as minor constituents in zinc
sulfide ore, which was the primary raw material used in
smelting operations at the Palmerton smelting plants. Previ-
ous studies as well as the RI/FS have shown heavy metals in
measurable amounts in soils in the surrounding Palmerton
area, with the highest concentrations present in soils immedi-
ately surrounding the East and West Plants. Emissions from
the smelters also caused the defoliation of approximately
2,000 acres on Blue Mountain.
Data from the draft RI report (ZCA, 1987) was used to
select the shallow aquifer at the site as the candidate waste
stream for the technology demonstration. Groundwater
samples collected by EPA in June 1989 indicated that the
shallow groundwater is contaminated with high levels of zinc
(400 to 500 mg/L) and trace levels of cadmium (1 mg/L),
copper (0.02 mg/L), lead (0.015 mg/L), and selenium (0.05
mg/L).
Review of SITE Demonstration
The SITE demonstration was divided into three phases:
(1) site preparation; (2) technology demonstration; and (3)
site demobilization. These activities and a review of technol-
ogy and equipment performance during these phases are
described below.
Site Preparation
Approximately 10,000 square feet of relatively flat ground
surface was used for the microfilttation system and support
equipment and facilities, such a.s a filtrate storage tank,
nonhazardous and potentially hazardous waste storage con-
tainers, office and field laboratory trailer, and a parking area.
A temporary enclosure covering approximately one-third of
the demonstration area was erected to provide shelter for the
microfiltration system during inclement weather. A second-
ary containment area was provided for the tanks holding
treated and untreated groundwater to collect any spills or
leakage. Site preparation included setting up major support
equipment, on-site support services, and utilities.
Major Support Equipment
Support equipment for the microfiltration system in-
cluded storage tanks for untreated and treated groundwater,
storage tanks for equipment washdown and decontamination
rinse waters, equipment for treated effluent disposal, a
dumpster, a forklift with operator, a bulldozer with operator,
pumps, sampling equipment, health and safety-related gear,
and a van. Specific items include:
27
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Palmerton
Allentown
Philadelphia
SCALE: 1" = 1 Mile
Pennsylvania
Figure B-1. PZS Site Location Map.
28
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One 1,600-gallon tank mounted on a truck to
transport the groundwater required to perform
all test runs. Groundwater was collected from
well RCRA-4, transported to the demonstration
area, and pumped into a 6,000-gallon storage
tank.
One 6,000-gallon filtrate storage tank sized to
contain the filtrate from all test runs.
One 4,500-gallon storage tank to contain the
equipment washdown and decontamination rinse
waters.
One 1,000-gallon storage tank to store tap water
required for equipment and personnel
decontamination.
• One 1,000-gallon storage tank to store deionized
water required for equipment decontamination.
One 1,600-gallon storage tank to temporarily
store (1) the metals precipitate sludge remaining
at the end of each run, (2) filtrate collected
during the cake drying cycle, and (3) equipment
washwater. This waste was temporarily stored
in this tank until it was treated and pumped to
the 4,500-gallon storage tank for appropriate
disposal.
• One solid waste dumpster to store nonhazardous
wastes prior to disposal.
A number of 55-gallon drums to contain filter
cake, used filter media, and used disposable
health and safety gear prior to disposal.
A high-pressure steam cleaner for decontam-
inating the storage tanks and sampling
equipment at the end of the demonstration.
• A bulldozer with operator to clear and grade
the demonstration area.
A forklift with operator for setting up equipment
and for moving drummed wastes.
• One pump for transferring the contaminated
shallow groundwater from well RCRA-4 to the
tank truck, and from the tank truck to the
untreated groundwater storage tank. An
additional pump was needed to transfer the
filtrate from the filtrate storage tank to a tank
truck.
An air compressor and related equipment for
generating compressed air at 90 psig minimum
and 40 scfm capacity. This compressed air was
used in operating the microfiltration unit.
Sampling equipment to sample filter cake and
aqueous media.
Analytical equipment for measuring field
parameters at the demonstration site.
Health and safety-related equipment, such as a
first-aid kit and protective coveralls, latex or
similar inner gloves, nitrile outer gloves, steel-
toe boots and disposable overboots, safety
glasses, and a hard hat.
• A van to transport oversight personnel and
supplies.
On-Site Support Services
On-site laboratory analyses were conducted in a field
trailer measuring 12 by 44 feet. The field trailer also served
as an office for field personnel and provided shelter and
storage for small equipment and supplies. A personal com-
puter and printer were used for data processing. Two chemi-
cal toilets were located near the trailer.
Utilities
Utilities required for the demonstration included water,
electricity, and telephone service. Water was required for the
equipment and personnel decontamination and for drinking
purposes. During operation of the demonstration unit, per-
sonnel and equipment decontamination required about 50
gallons per day (gpd) of tap water. Deionized water needs
for final equipment decontamination were approximately 50
gpd. Drinking water needs were 5 to 10 gpd.
Electricity was needed for the microfiltration system, the
office trailer, and the laboratory equipment. The
microfiltration system required 240-volt, 3-phase, 60-Hz, and
20-amp electrical service. Additional electrical power (110-
volt, single-phase) was needed mainly for operating the
microfiltration system's agitators, lighting the office trailer,
and operating the on-site laboratory and office equipment. A
portable generator was used during the initial 2 weeks of the
demonstration because Pennsylvamia Power and Light Com-
pany could not provide the electrical connection due to rainy
weather.
Telephone service was required mainly for ordering
equipment, parts, reagents and other chemical supplies;
scheduling deliveries; and making emergency communica-
tions.
Technology Demonstration
This section discusses operalional and equipment prob-
lems and health and safety issues associated with the SITE
demonstration.
Operational Problems
The SITE team experienced a few operational problems
during the demonstration. Some of these problems resulted
in changes in the demonstration schedule and duration, while
the others required making field decisions to solve the prob-
lems. These operational problems and their resolutions are
described below.
Pennsylvania Power and Light Company could
not provide electrical power connection for
onsite operations during the first 2 weeks of
demonstration. The SITE, team rented a portable
generator to perform the field work during this
period. Although the generator could provide
adequate power supply, field personnel had to
make frequent trips to diesel fuel stations to
obtain diesel for the generator. Sometimes, the
voltage fluctuations by the generator resulted in
minor problems in the operation of field
analytical instruments.
According to the technology developers, several
additional dry runs had to be performed because
the groundwater characteristics during the
demonstration were slighfly different from those
for the treatability studies performed in June
29
-------
1989. In the dry runs, it was found that the
volume of filtrate generated in each filtration
cycle was significantly less than the quantity
the developers anticipated. Because of this, the
filtrate collection and recirculation tanks were
too large to implement the sampling procedures
planned for the demonstration. To solve this
problem, significant modifications were made
to the tanks used, the sampling approaches, and
the number of cycles per run. This resulted in
equipment modifications and demonstration
schedule changes.
Equipment Problems
The SITE team experienced a few equipment problems
during the demonstration. These problems resulted in (1)
repeating the demonstration runs, (2) onsite equipment
maintenance, and (3) changes in the demonstration schedule
and duration. These equipment problems and their resolu-
tions are described below.
• At the beginning of the demonstration, the filter
aid pump did not deliver the rated flow rate due
to cold weather. For example, when the pump
was set at its maximum, it delivered only 16
gallons per hour (gph) instead of 40 gph. After
the hydraulic oil in the pump warmed up and
the filter pump was recalibrated onsite, the pump
was able to deliver the desired flow rate.
• The filter feed pump flow rate could not be
controlled properly because of the excessive air
supply to the pump. The developer replaced
the 0.5-inch air line with 0.25-inch air line and
this solved the problem.
The moisture trap of the compressor was not
adequate to dry compressed air for proper
functioning of the microfiltration system.
Because of this, the pneumatic controls of the
microfiltration system malfunctioned, and the
pump flow rates could not be controlled properly
in some runs. The moisture in the air lines had
to be removed every few hours to minimize
moisture accumulation. The demonstration runs
impacted by this problem had to be repeated.
• The ProFix pump and the lines clogged
frequently. To minimize this problem, ProFix
was sieved through a Number 10 mesh size
screen and also ProFix slurry was diluted from
9 percent to 6 percent. According to the
developer, all commercially available ProFix is
now screened to eliminate this problem.
• In one run, the filter media reroller did not
function properly. The filter media did not reroll
automatically at the end of some filtration cycles
because the reroller did not have adequate
tension. The developer discovered that it was
because the clutch on the reroller slipped. The
clutch was then repaired for proper functioning
of the microfiltration unit.
• During the latter runs, it was found that the
scraper bar on the microfiltration unit punctured
the filter media because the scraper bar surface
was not smooth. This problem was resolved by
removing the scraper bar and using a new
segment of filter media. This run was also
repeated. The developer states that most
commercially available filters have smooth
scraper bars.
Health and Safety Considerations
In general, health hazards associated with the demon-
stration resulted from the possibility of exposure to the con-
taminated groundwater. Although the treatment system was
entirely closed, the potential routes of exposure during the
demonstration were inhalation, ingestion, and skin and eye
contact from possible splashes or spills during sample col-
lection.
All personnel working in this area had, at a minimum,
40 hours of health and safety training and were under routine
medical surveillance. Personnel were required to wear pro-
tective equipment appropriate for the activity being per-
formed. Steel-toe boots were required in the exclusion zone.
Personnel working in direct contact with contaminated
groundwater were in modified Level D protective equipment,
including safety shoes, latex inner gloves, nitrile or Viton
outer gloves, and safety glasses.
Site Demobilization
Decontamination was necessary for the DuPont/Oberlin
demonstration unit, untreated groundwater storage tank, treated
effluent storage tank, and sampling equipment.
The storage tanks were steam-cleaned at the end of the
demonstration program. Filtrate collected during the demon-
stration was tested and discharged into an on-site treatment
facility. Filter cake, along with disposable protective cloth-
ing such as coveralls, was collected in 55-gallon drums and
disposed of at a permitted nonhazardous waste landfill.
After the demonstration program was completed and on-
site equipment was disassembled and decontaminated, equip-
ment and site demobilization activities began. Equipment
demobilization included loading the skid-mounted units on a
flat-bed trailer and transporting them off-site, returning rented
support equipment, and disconnecting utilities.
Experimental Design
The objectives of the technology demonstration were to:
(1) assess the technology's ability to remove zinc from the
groundwater at the PZS sjte under different operating condi-
tions, (2) evaluate the system's ability to dewater the metals
precipitate from treated groundwater at the PZS site, (3)
determine the system's ability to produce a filtrate and a
filter cake that meet applicable disposal requirements; and
(4) develop the information required to estimate the operat-
ing costs for the treatment system, such as electrical power
consumption and chemical doses.
Testing Approach
The technology evaluation was performed in four phases.
Phases 1 and 2 involved nine runs each, and Phases 3 and 4
involved two runs each. In Phase 1, chemical operating
parameters (precipitation pH and ProFix dose) were varied,
30
-------
and the filter operating parameters (blowdown pressure and
blowdown time) were kept constant. In Phase 2, the filter
operating parameters were varied, and the chemical operat-
ing parameters were kept constant. Phase 3 runs were per-
formed to evaluate the reproducibility of the microfiltration
system's performance. Phase 4 runs were performed to
evaluate the reusability of the Tyvek® Filter.
Table B-l summarizes the operating conditions for the
demonstration runs. For Phase 1 runs, the initial operating
conditions (Run 1) were based on a pilot-scale treatability
study performed by DuPont/Oberlin on the PZS site ground-
water. During the demonstration, the chemical operating
conditions and the filter operating conditions were optimized
in Phases 1 and 2, respectively. Since Run 5 conditions were
selected as the optimum operating conditions for Phase 1,
these were set as the initial conditions for Phase 2. Phases 3
and 4 were performed at Run 13 conditions because these
conditions were selected as the overall optimum operating
conditions. This experimental design assumes that there is
no interaction effect between the chemical and filter operat-
ing parameters. Although this assumption is not critical to
evaluating the microfiltration system based on the technol-
ogy demonstration objectives, the technology developers
agreed with this assumption based on their experience.
Sampling and Analytical Procedures
Solids and water samples were collected from the
microfiltration system at the locations shown on Figure B-2.
The following measurements were considered critical to
evaluating the microfiltration system: (1) zinc in the untreated
groundwater and filtrate, (2) total suspended solids (TSS)
before and after the microfiltration unit, (3) free liquids
(paint filter liquids test) and moisture content in the filter
cake, and (4) pH of the untreated groundwater and filtrate.
Several noncritical measurements were also performed, in-
cluding the extraction procedure (EP) toxicity test and toxic-
ity characteristic leaching procedure (TCLP) test for the filter
cake, and particle size distribution for the filtrate. For the
critical measurements, about three to six replicate samples
were collected depending on the data variability. Duplicate
samples were collected for noncritical measurements.
EPA-approved sampling, analytical, quality assurance,
and quality control (QA/QC) procedures were followed to
obtain reliable data. Details on QA/QC procedures are pre-
sented in the demonstration plan (PRC, 1990). Table B-2
summarizes analytical and measurement methods.
Review of Treatment Results
This section summarizes the results of both critical and
noncritical parameters for the DuPont/Oberlin microfiltration
system demonstration and evaluates the microfiltration
technology's effectiveness in treating groundwater contami-
nated with zinc.
Summary of Results for Critical Parameters
Results for the critical parameters were evaluated for
each of the four phases.
Phase 1 Results
The total zinc concentrations in the untreated groundwa-
ter and filtrate are presented in Figure B-3 for varying pre-
cipitation pH and ProFix doses. The zinc concentrations in
the untreated groundwater, ranging from 417 to 493 mg/L,
were reduced to about 0.1 mg/L (except in Run 6), yielding
a typical removal efficiency of Beater than 99.9 (3 logs)
percent. In Run 6, the filtrate zinc concentration was an order
of magnitude higher than the typical filtrate zinc level; this
increased concentration cannot be explained. No definite
trend was identified for effluent zinc levels or zinc removal
efficiencies with varying pH or ProFix dose.
During the demonstration, a simple of the influent to the
microfiltration unit was filtered through a standard 0.45-pm
membrane filter (commonly used to measure dissolved) met-
als) to compare the resulting filtrate with T-980 filtrate. In all
cases, the zinc concentration was less in the T-980 filtrate,
indicating the possible superior performance of Ty vek® T-980
filter media.
Figure B-4 presents the TSS concentration profiles for
influent and filtrate. These data show that the influent TSS
concentrations ranged from 6.5601 to 18,900 mg/L, and the
filtrate TSS concentrations ranged from 8.4 to 31.5 mg/L.
The TSS removal efficiencies ranged from 99.69 to 99.95
percent. Neither filtrate TSS levels nor TSS removal effi-
ciencies seemed to follow a definite trend with varying pH or
ProFix dose.
The filter cake solids levels are presented on Figure B-5.
This figure shows that cake solids ranged from 30.5 to 47.1
percent. This figure also shows mat the cake percent solids
increased as the pH or ProFix dose increased. The filter cake
passed the paint filter liquids test in all runs, making it
suitable for landfilling.
The filtrate pH was typically about 11.5, irrespective of
the precipitation pH due to the high pH (about 12.6) of the
ProFix slurry added at the influent to the microfiltration unit.
At the end of Phase 1, Run 5 conditions were selected as
the optimum chemical operating conditions based on (1) zinc
and TSS removals, (2) zinc and TSS levels in the filtrate, (3)
percent solids in the filter cake, and (4) the cost of treatment
chemicals (lime and ProFix).
Phase 2 Results
Figures B-6, B-7, and B-8 present the concentrations
profiles for zinc, TSS, and filter cake solids, respectively.
These results are similar to Phase 1 results. The filter cake
passed the paint filter liquids test in all Phase 2 runs, and the
filtrate pH was typically about 11.5 (same as that in Phase 1
runs).
A dissimilarity was noted between the Phase 1 and
Phase 2 results for Tyvek® T-980 filtrate and 0.45-|im fil-
trate. In the Phase 2 runs, the zinc concentrations in the
Tyvek® T-980 filtrate were not always less man the 0.45-|jm
filtrate. This dissimilarity cannot be explained.
At the end of the Phase 2 runs, Run 13 conditions were
selected as the optimum operating conditions based on the
criteria discussed for Phase 1, plus waste processing time
(which includes blowdown time).
31
-------
Table B-1. Operating Conditions for the Demonstration Runs
Phase Run No.
1 1
2
3
4
5
6
7
8
9
2 10
11
' 12
13
14
15
16
17
18
3 19
20
4 21
22
Precipitation pH
8
9
10
8
9
10
8
9
10
9
9
9
9
9
9
9
9
9
9
9
9
9 I
ProFix Dose (g/L)
6
6
6
12
12
12
14
14
14
12
12
12
12
12
12
12
12
12
12
12
12
12
Time (Min)
2
2
2
2
2
2
2
2
2
0.5
2
3
0.5
2
3
0.5
2
3
0.5
0.5
0.5
0.5
Pressure(psig)
45
45
45
45
45
45
45
45
45
30
30
30
38
38
38
45
45
45
38
38
38
38
Phase 3 Results
The total zinc concentration in the untreated groundwa-
ter in Runs 19 and 20 (reproducibility runs performed at Run
13 operating conditions) was 465 mg/L. This was reduced
by 99.95 and 99.94 percent, resulting in 0.24 and 0.28 mg/L
of zinc in Runs 19 and 20, respectively. These removal
efficiencies agree with the removal efficiency achieved in
Run 13 (99.95 percent), indicating that the microfiltration
system's performance in removing zinc was reproducible.
The TSS concentrations in the influent to the
microfiltration unit were 14,300 and 14,000 mg/L in Runs 19
and 20, respectively. These were reduced by 99.95 percent,
resulting in 7.7 and 6.8 mg/L of TSS in Runs 19 and 20,
respectively. This removal efficiency also agrees with the
TSS removal efficiency observed in Run 13 (99.91 percent),
indicating that the system's performance in removing TSS
was reproducible.
32
-------
Groundwater
Liquid Sampling Location
Solids Sampling Location
— To
Disposal
To
Disposal
To Liquid
Waste Storage
nitrate
Recirculation
Tank
Figure B-2. Microfiltration System Sampling Locations.
33
-------
Table B-2. Analytical and Measurement Methods
Parameter
Metals (total)
Metals (dissolved)
EP Toxicity
TCLP
Metals (total)
Free Liquids
Moisture Content
TSS
Acidity
Particle Size
Temperature
pH
Turbidity
Volume
Mass
Electricity
Consumption
Notes a L = Liquids
S = Solids
O = Others
Matrix'
L
L
S
S
S
S
S
L
L
L
L
L
L
S,L
S
0
Method
Type
Lab
Lab
Lab
Lab
Lab
Field,
Field
Field
Field
Lab
Field
Field
Field
Field
Field
Field
Method Reference
SW-846 3010/6010b
SW-846 3005/6010b
SW-846 1310b
SW-846 3010/6010b
40 CFR Part 268°
SW-846 3050/6010
SW-846 9095b
SM209F1
MCAWW 160.2e
MCAWW 305 le
Coulter Corporation
Manufacturer Spec.
MCAWW 170.1e
MCAWW 150.16
MCAWW 180. le
NAf
NAf
NAf
Title
Metals by ICP
Metals by ICP
Extraction
Metals by ICP
Toxicity
Characteristic
Leaching
Procedure
Metals by ICP
Paint Filter
Liquids Tests
Percent Solids
Residue
(filterable)
Acidity
(Titrimetric)
Particle Size
Analysis
Temperature
pH
Turbidity
Volume
Mass
Electricity
Consumption
b U.S. EPA. 1986.
c. 40CFR.1988
d APHA.AWWA.andWPCF, 1989.
c U.S. EPA, 1983
f NA = Not available
34
-------
Figure B-9 compares regulatory thresholds with (1) the
95 percent upper confidence limits (UCL) for filtrate metals
Cadmium, lead, and zinc) and TSS and (2) the average
filtrate pH value, the regulatory thresholds are those that
would be required for discharge into a local waterway
(Aquashicola Creek) if an NPDES permit were required. The
UCLs were calculated using the one-tailed Student's t-test.
To calculate UCLs for cadmium and lead, which were present
below detection limits, their mean concentrations were esti-
mated using standard statistical procedures. Figure B-9 shows
that the filtrate met the NPDES limits for metals and TSS.
However, the NPDES limit for pH was not met.
Figure B-10 presents the composition of the filter cake in
the reproducibility runs. Percent solids in the filter cake was
about 41. Of these solids, about 80 to 90 percent were from
ProFix, and the remaining were from (1) TSS present in the
untreated groundwater: (2) metals precipitated during the
treatment; and (3) any unreacted lime from pH adjustment.
As a quality control check, a mass balance was per-
formed for zinc and TSS in Runs 19 and 20. The mass
balance results for zinc showed that the difference between
zinc in and zinc out was about 15 percent, which is within
analytical precision (+ 25 percent). Similarly, TSS measure-
ments were also within analytical precision (± 30 percent).
Phase 4 Results
The results for the Tyvek® reusability runs (Runs 21 and
22) are presented on Figure B-ll. In these runs, the same
portion of Tyvek® was used repeatedly for six cycles. Samples
were composited after the first three cycles (Run 21) and the
last three cycles (Run 22). Figure B-ll shows that the
microfiltration unit's performance was unaffected even after
multiple uses of Tyvek®.
Summary of Results for Noncritical Parameters
The demonstration also evaluated the results for
noncritical parameters such as filter cake toxicity characteris-
tics and the filtrate particle size distribution. Toxicity charac-
teristics were considered a noncritical parameter because EP
and TCLP metals were present at very low levels in the
untreated groundwater. The particle size distribution mea-
surement was included primarily to evaluate the developers'
claim that the Tyvek® filter can remove particles down to 0.1
micron (|J.m). The filter cake toxicity characteristics were
determined using EP and TCLP tests. A composite filter cake
sample collected from the demonstration runs passed both
these tests, indicating that the filter cake could be disposed of
as a nonhazardous waste.
Figure B-12 presents the filtrate particle size distribution
and TSS results for the reproducibility runs. The particle size
was measured using a Coulter counter with a 0.5-to 500-|j.m
measurement range. The data presented on this figure indi-
cate that the majority of particles present in the filtrate were 1
to 4 pun in size. The TSS data for these runs were used
together with the particle size distribution to estimate the
particle concentration in each size range. In Run 13 for
example, filtrate particles ranging from 1 to 2 pm and greater
than 8 pm were present at 6.3 mg/L and 0.63 mg/L, respec-
tively. These results do not support the developers' claim
that the Tyvek® filter can remove particles down to 0.1 pm.
Similar observations were made for Runs 19 and 20.
After reviewing the particle size distribution and TSS
data, DuPont stated that the TSS measured in the filtrate was
the result of postprecipitation of calcium carbonate solids.
DuPont provided X-ray diffraction data for the TSS collected
on a 0.45-jim filter by processing the filtrate from the
microfiltration unit in Phase 1 runs. The X-ray diffraction
data showed a much stronger peak for calcium carbonate
solids than for zinc solids; however, quantitative data were
not available. DuPont also stated that the filtrate turbidity it
measured immediately after sample collection typically ranged
from 0.1 to 0.3 NTU and that TSS values were about 0.2
mg/L. These levels are lower than those observed by EPA,
although EPA analyzed its samples well within the holding
times specified by EPA-approved analytical methods. DuPont
observed that both turbidity and TSS levels in the filtrate
samples increased overnight, indicating postprecipitation ef-
fects. Such observations were not made during the pilot-
scale tests performed before the demonstration, perhaps be-
cause die batch of groundwater used during the pilot-scale
testing was different from that used during the demonstra-
tion.
Conclusions
The DuPont/Oberlin microfiltration system achieved the
following: (1) zinc and TSS removal efficiencies of 99.69 to
99.99 percent and (2) solids in the filter cake of 30.5 to 47.1
percent. At the optimum conditions (Run 13), the zinc and
TSS removal efficiencies were about 99.95 percent and the
filter cake solids were about 41 percent.
ProFix contributed a significant portion (80 to 90 per-
cent) of solids to the filter cake. The remaining solids were
due to precipitated metals, TSS from the untreated ground-
water, and any unreacted lime.
The zinc and TSS removal efficiencies and the filter
cake percent solids were unaffected by the repeated use (six
cycles) of the Tyvek® filter media. This indicates that the
Tyvek® media could be reused without adversely affecting
the microfiltration system's performance.
The filtrate met the applicable NPDES permit limits,
established for disposal into a local waterway, for metals and
TSS at the 95 percent confidence level. However, the filtrate
did not meet the NPDES permit limit for pH. The filtrate pH
was typically 11.5, while the permit limit is 6 to 9.
The filter cake passed the paint filter liquids test for all
runs. Also, a composite filter cake sample from the demon-
stration runs passed the EP toxicity and TCLP tests.
35
-------
Zinc Concentration, mg/L
.01
.1
10
100
1,000
lUlUIUUlUIUttl.
Run1 i
illllililll!l!il.06
pH 9
10
UilitlUUlUMM
Run 2
!.07
lUUUIUIUUIUU
Run3
XJ8J
417
417
LOW
PROFIX
DOSE
(6Q/L)
.01
.1
10
100
1,000
pH 9
MEDIUM
PROFIX
DOSE
(12Q/L)
100
1,000
HIGH
PROFIX
DOSE
(149/L)
Untreated Groundwater
Filtrate
Figure B-3. Zinc Concentration Profiles for Phase 1 Runs.
36
-------
TSS Concentration, mg/L
100 1,000 10,000
100,000
LOW
PROFIX
DOSE
(69/L)
PH
1,000 10,000
I I I I I I I
100,000
pH 9
.•'".". .'".-'V ll,31.5
MEDIUM
PROFIX
DOSE
(12g/L)
100,000
HIGH
PROFIX
DOSE
(14Q/L)
Influent to Microfiltration Unit
Filtrate
FigureB-4. TSS Concentration Profiles for Phase 1 Runs.
37
-------
Cake Solids, %
10
pH 9
LOW
PROFIX
DOSE
(6g/L)
10
20
MEDIUM
PROFIX
DOSE
(12g/L)
HIGH
PROFIX
DOSE
(149/L)
Figure B-5. Filter Cake Solids for Phase 1 Runs.
38
-------
Zinc Concentration, mg/L
100 1,000
Slowdown
Time, min.
LOW
SLOWDOWN
PRESSURE
(30psig)
100 1,000
Slowdown
Time, min.
MEDIUM
SLOWDOWN
PRESSURE
(38psig)
.01
.1
0.5
Slowdown
Time, min.
Run 17 lilt
10
100 1,000
HIGH
SLOWDOWN
PRESSURE
(45psig)
Untreated Groundwater
Figure B-6. Zinc Concentration Pofiles for Phase 2 Runs.
Filtrate
39
-------
TSS Concentration, mg/L
100 1,000
i L.'... '..'.. '..'.I i .'
10,000 100,000
.1 — ' — ' — ' ' ' ' "
Slowdown 2
Time, min.
LOW
SLOWDOWN
PRESSURE
(30psig)
0.5
Slowdown
Time, min.
10 100
~i—i i i i iii "i i i i~n
Run 13
1:10.9
Run 14
18.3
Run 15
1,000
-j ....... i i i 1 1 1 n i
10,000 100,000
"i—i—i i i 111
12,500
9,460
15,100
MEDIUM
SLOWDOWN
PRESSURE
(38psig)
1,000 10,000 100,000
0.5
Slowdown 2
Time, min.
HIGH
SLOWDOWN
PRESSURE
(45pslg)
Klllliil Influent to Microfiltration Unit [ i:;;,:,!;,:,;! Filtrate
Rgure B-7. TSS Concentration Profiles for Phase 2 Runs.
40
-------
Cake Solids, %
Blowdown
Time, min.
LOW
BLOWDOWN
PRESSURE
(30psig)
Slowdown
Time, min.
Run 14 ';;;j:";:',!i: -, .;j!S"_ ,!jj|jt ' ^X! ' .. ..''Ijiji.;;''", |'|"''41.8
MEDIUM
BLOWDOWN
PRESSURE
(38psig)
Slowdown
Time, min.
HIGH
BLOWDOWN
PRESSURE
(45psig)
Figure B-8. Flilter Cake Solids for Phase 2 Runs.
41
-------
10,000E
1,000
0)
O 100
10
O5
10
Regulatory Threshold
RT = 200
Metals
RT = 700
Zinc
TSS
PH
40
J 30
I
_F
O 20
to
O5
10
RT = 30
14
12
ID 8
X
°- 6
4
2
0
. 13 4.
IRun r
k- 19 y.-
I 20 jr.
Rgura B-9. Comparison of Filtrate Quality for Reproduclbility Runs with Regulatory Thresholds.
42
-------
Figure B-10. Filter Cake Composition for Reproducibility Runs.
43
-------
Zinc Concentration, mg/L
1 10 100
1,000
10
TSS Concentration, mg/L
100 1,000 10,000 100,000
Cake Solids, %
30 40
50
Untreated Groundwater
Influent to Microfiltration Unit
Rgure B-11. Tyvek" Performance for Reusability Runs.
;M/:n;, Filtrate
Filter Cake
44
-------
10
Number of Particles, percent
20 30 40
34.6
50
rss =
18.3 mg/L
RUN 13
N
CO
^)
O
RUN 19
N
CO
JO)
o
'
RUN 20
Figure B-12. Filtrate Particle Size Distribution for Reproducibility Runs.
45
-------
References
APHA, AWWA, and WPCF, 1989. Standard Methods for
the Examination of Water and Wastewater, 17th Ed.,
Washington, D.C.
40 CFR, Part 268, 1988. Toxicity Characteristic Leaching
Procedure (Appendix I).
U.S. EPA, 1983. Methods for the Chemical Analysis of
Water and Wastes, EPA-600/4-79-020 U.S. EPA
Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio.
PRC, 1990. Demonstration Plan for the DuPontlOberlin
Microfiltration System, prepared for U.S. EPA, April
1990
U.S. EPA 1986. Test Methods for Evaluating Solid Waste,
Volumes IA-IC: Laboratory Manual Physical/Chemical
Methods; and Volume II: Field Manual, Physical/
Chemical Methods, SW-846, Third Edition, Office of
Solid Waste, Washington, D.C.
ZCA, 1987. Draft Remedial Investigation Report for the
Palmerton Zinc Superfund Site, Palmerton, Pennsylvania.
46
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Appendix C
Case Studies
Introduction
This appendix summarizes case studies on the use of the
DuPont/Oberlin microfiltration technology. These case stud-
ies describe the performance of full-scale DuPont/Oberlin
microfiltration units treating industrial wastewaters. The in-
formation available for these case studies varies from de-
tailed analytical and cost data to relatively little information
on system performance and cost. The following case studies
are summarized in this appendix:
Case Study
Facility and Location
C-l Westinghouse Savannah River Site, Aiken,
South Carolina
C-2 DuPont Electronics Materials, Inc., Manati,
Puerto Rico
C-3 DuPont Electronics, Sun Valley, California
47
-------
Case Study C-l
Westinghouse Savannah River Site
Aiken, South Carolina
This case study presents the results of full-scale testing
and use of a DuPont/Oberlin microfiltration system at the
Weslinghouse Savannah River site (SRS) in Aiken, South
Carolina. The microfiltration system uses Tyvek® T-980 filter
media to remove submicron particles from wastewater. SRS
began using this system in July 1985 to treat wastewater from
its metal finishing and aluminum forming operations and
from an autoclave process.
A series of tests were conducted to evaluate the effec-
tiveness of the DuPont/Oberlin microfiltration system at the
SRS. The performance of the filtration unit was studied as a
function of several variables including filter media, filter aid,
and polymer additive. The results of these tests are presented
below. The information presented in this case study is based
on a paper presented by Mr. Hollis Martin of Westinghouse
at the American Electroplaters and Surface Finishers/Envi-
ronmental Protection Agency (EPA) Conference on Ppllution
Control for the Metal Finishing Industry in January 1989, as
well as current data on system operations provided by Mr.
Martin.
Facility Operations
The Savannah River Plant produces nuclear materials for
the U.S. Department of Energy (DOE). The facility is man-
aged for DOE by Westinghouse as of April 1, 1989 (prior to
that by DuPont). Fuel and target assemblies for the nuclear
reactors of the Savannah River Plant are fabricated in the
300-M area of the facility. Metal finishing, aluminum form-
ing, and various cleaning operations in the 300-M area pro-
duce effluents that discharge to a wastewater treatment plant.
Principal metals in the wastewater include uranium, alumi-
num, nickel, lead, zinc, copper, and chromium. These metals
are removed from the effluent by wastewater equalization,
precipitation, flocculation, and microfiltration. A second
waste stream, consisting of insoluble metal oxides from auto-
clave test effluent, is treated by a separate wastewater equal-
ization and microfiltration system. The chemical composi-
tions of wastewaters from 300-M area and autoclave opera-
tions are shown in Table C-l-1.
Prior to undergoing pressure filtration, 300-M area
wastewater is acidified to pH 3, and aluminum sulfate is
added to ensure phosphate removal. The pH is then raised to
approximately 8 by addition of sodium hydroxide to precipi-
tate the metals. This pretreated wastewater is filtered using
the microfiltration system, which is the primary unit opera-
tion in treating 300-M area wastewater. The filtrate is ana-
lyzed and discharged to Tims Branch Creek in South Caro-
lina. The average composition of the filtrate discharged in
June 1990 and associated National Pollutant Discharge
Elimination System (NPDES) limits are presented in Table
C-l-1. The filter cake contains both hazardous (F006) and
radioactive material; therefore, it is considered a mixed waste.
Prior to disposal, the filter cake is stabilized and solidified
with cement. The treated filter cake is subject to hazardous
waste land disposal restrictions.
System Performance
The performance of the DuPonl/Oberlin microfiltration
systems was evaluated following changes in filter media,
filter aid, and polymer additives. These investigations were
motivated by a rising peak demand for the two filtration
units and a consequent need for greater efficiency. The ef-
fects of these changes and a summary of the maintenance
provided for the system over the last 5 years are presented
below.
Filter Media
The Oberlin pressure filtration systems were installed at
the 300-M area of the Savannah River Plant in July 1985.
The filtration area of each unit is 24 square feet. Originally,
Tyvek® 1042B was chosen because of its high filtration effi-
ciency and good sheet tensile and tear strength compared to
other filter media. When DuPont developed a new Tyvek®
series specifically designed for filtration applications, DuPont
conducted tests comparing the new Tyvek® T-980 media with
the original Tyvek® 1042B. Wastewater from the 300-M and
autoclave areas were used to test the two Tyvek® materials; the
same batches of wastewater were used for the comparison.
Tyvek® T-980 increased the cycle time and average flow
rate through the filter by 13 and 11 percent, respectively, for
effluent from the 300-M area operations. The filtrate turbid-
ity did not differ significantly between the two filter media.
For the autoclave wastewater, the cycle time remained ap-
proximately the same; however, the average flow rate through
the filter increased by 9 percent, and the filtrate turbidity
decreased by 40 percent. The increased filtration flow rate
observed for both systems using Tyvek® T-980 indicates that
the new filter media increases the efficiency of the
microfiltration system.
Tyvek® T-980 was also compared to other filter media,
such as a wet cast microporous membrane, biaxial stretch
polytetrafluoroethylene laminated membrane, and melt blown
polypropylene media. The performance of these media com-
pared to Tyvek® T-980 for filtering the 300-M area wastewa-
ter was investigated. Tyvek® T-980 outperformed other filler
media by producing a clearer filtrate with the best cake
release from the media. Furthermore, the filter cake from
Tyvek® T-980 had the highest solids content. A high solids
48
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Table C-l-1. Operating Data for the DuPont/Oberlin Microfiltration System
Contaminant
300-M
Wastewater*
mg/L
Filtrate
mg/L
Autoclave
Wastewater"
mg/L
NPDES Permit Limits
Filtrate
mg/L
Daily Max.
mg/L
Monthly Average
mg/L
Uranium
Aluminum
Nickel
Lead
Zinc
Copper
Cadmium
Chromium
Nitrate (as N)
Phosphate (as P)
pH
Total Suspended
Notes: a
b
c
2.59
180.0
12.14
0.79
0.54
0.18
<0.1
0.1
685.0
4.46
8.4
Solids 800
0.03
1.97
<0.1
0.1
<0.1
<0.1
<0.1
<0.1
634.0
3.00
8.3
5
16.3 < 0.1
0.25 < 0.1
0.04 < 0.1
0.04 < 0.1
< 0.1 < 0.1
0.04 < 0.1
< 0.1 < 0.1
< 0.1 < 0.1
0.03 < 0.1
0.11 <0.1
NAC NA
300 <4
1.0b
6.43
2.46
0..69
0..64
0,42
0.1
1..24
l,355.0b
16.7b
6.0 - 10.0
60
0.5"
3.2
1.23
0.43
0.32
0.21
0.05
0.62
677.0b
6.83b
NA
31
The values are monthly averages based on daily analyses.
These values are only guidelines.
Not available.
content generally indicates a lower volume of waste requir-
ing disposal.
Filter Aid
Fine grades of diatomaceous earth were initially used as
filter aids in 300-M area wastewater treatment with the Tyvek®
1042B media. When a significant concentration of 1 to 3
micron particles (nickel and iron) were present, Celite 577
was used; when wastewater contained particles greater than 3
microns, Standard Super-Cel was used. These filter aids
were tested against PerFLO 30SP, a new high-grade filter
aid. DuPont compared the performance of selected combina-
tions of filter media and filter aid while filtering the same
batch of wastewater.
Investigations using 300-M area wastewater focused on
the traditional combination of Tyvek® 1042B and Celite 577
and the new combination of Tyvek® T-980 and PerFLO
30SP. Compared to Tyvek® 1042B and Celite 577, the com-
bination of Tyvek® T-980 and PerFLO 30SP produced better
results: the filtrate contained 45 percent less suspended
solids and the average flow rate through the filter increased
by a factor of 2.5. In addition, the filtration cycle time
doubled. The increase in both the filtration cycle and the
flow rate resulted in approximately 5 times as much waste-
water filtered per cycle, and 80 percent less filter media was
used. The amount of filter aid required decreased 20 percent
with PerFLO 30SP compared to Celite 577.
A different set of filter media/filter aid combinations
were used to test filtration of the autoclave wastewater. In
this test series, Tyvek® T-980 was investigated using both
Celite 577 and PerFLO 30SP and compared to Tyvek® 1042B
and Standard Super-Cel. Although PerFLO 30SP greatly
improved the performance of the 300-M area wastewater
filtration system, it did not enhance the performance of the
autoclave wastewater filtration system. The combination of
Tyvek® T-980 and Celite 577 yielded the best results. Al-
though the feed cycle remained constant for all combina-
tions, flow rate increased 45 percent and the turbidity de-
creased 90 percent when Celite 577 was used. The micro-
structure of PerFLO 30SP, compared to diatomaceous earth
filter aids, limited the ability to caplure very fine metal oxide
particles found in the autoclave effluent.
49
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Polymers
During early operation of the microfiltration units, an
anionic polymer was added to the wastewater to increase
filtration efficiency. However, the polymer activation tank
was too large, allowing the polymer to age and form an
unfilterable slime. Therefore, use of polymer was tempo-
rarily discontinued.
Improvements in polymers and activation systems stimu-
lated new interest in polymer addition. Laboratory tests
indicated that 0.5 mg/L Praestol A3040L anionic polymer
would triple the filtration rate of metal hydroxide wastewater
containing 500 to 600 mg/L total suspended solids (TSS),
and 8 mg/L Praestol K144L cationic polymer would double
the filtration rate of metal phosphate wastewater containing
800 to 1,000 mg/L TSS when used with PerFLO 30SP filter
aid and Tyvek® T-980 filter media. Unique anionic and
cationic polymer addition systems were installed for full-
scale evaluation.
The performance of the polymers met with laboratory
expectations. Presently, 8 mg/L of Praestol K144L is used to
enhance metal phosphate removal from the wastewater.
Polymer addition further enhances the Tyvek® T-980/PerFLO
30SP combination by decreasing filter media and filter aid
usage by 7 and 3.4 times, respectively.
Maintenance
Due to a hydraulic problem in the filter feed system (not
part of the DuPont/Oberlin system), the filters have cycled at
four times their normal rate. Despite this excessive cycling,
maintenance during the 5 years of operation was minimal.
The media support belt is replaced about every 3 months,
and the diaphragm of the filter fed inlet valve is replaced
annually. The high pressure air bags on the upper platform
were replaced once in the past 5 years as a precaution. The
belt chains were replaced one time after a mechanic improp-
erly installed a replacement belt The Wilden M2 filter aid
feed pump diaphragms are replaced about every 6 months.
The top platen seal was replaced once in the past 5 years.
Costs
Solids removal capacity of the 300-M area and auto-
clave wastewater treatment facilities has been greatly in-
creased by the improved filter aid and media. The cost of
PerFLO 30SP filter aid is half that of fine grades of diatoma-
ceous earth; moreover, 20 percent less is needed. The new
filter media (Tyvek® T-980) also costs less to manufacture,
and 80 percent less is used. The operating and maintenance
cost, including polymer, filter aid, and filter media, is about
5 dollars per 1,000 gallons of wastewater processed.
Conclusions
Performance of the DuPont/Oberlin microfiltration sys-
tem for removing suspended metal hydroxides and metal
phosphates from wastewater is maximized by using Tyvek*
T-980 as the filter media, in conjunction with PerFLO 30SP
filter aid and Praestol K144L cationic polymer. The volume
of filter cake requiring disposal decreased by 15 percent.
Results of extraction procedure toxicity and toxicity charac-
teristic leaching procedure (TCLP) analyses of the listed
F006 mixed waste produced by this configuration satisfy
land disposal restrictions. EPA is reviewing the Westinghouse
petition for delisting the spent filter rolls. The effluent from
the microfiltration unit meets all NPDES requirements.
50
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Case Study C-2
DuPont Electronics Materials, Inc.
Manati, Puerto Rico
This case study presents information provided by DuPont
Electronics Materials, Inc. (DEMI) on the application of the
DuPont/Oberlin microfiltration system at the company's fa-
cility in Manati, Puerto Rico. Little information is available
for this case study regarding facility operations, system per-
formance, and costs.
Facility Operations
Operations at the DEMI facility produce a wastewater
slurry of 2,000 gallons per day. The slurry contains 1,000 to
5,000 parts per million (ppm) of suspended "frit" (calcinated
or partly fused, high-lead content glass material) and 2,000
to 10,000 ppm of total suspended solids.
System Performance
The objective of the facility's microfiltration treatment
unit is to remove suspended particulates from the wastewater
slurry ranging from 0.5 to 30 microns in size. Before
filtration, two additives are combined with the wastewater to
assist in filtration: a filter aid and an organic polymer. The
filter aid is an amorphous volcanic aluminum silicate. Ap-
proximately 12 pounds of filter aid is added per filtration
cycle (440 gallons of process water). Approximately 10
milliliters of 0.1 percent quaternary acrylamide cationic poly-
mer is added per cycle.
The microfiltration system uses Tyvek® T-980 filter me-
dia. According to DuPont, the microfiltration system re-
placed 0.45 micron cartridges, which were costing the plant
$1,200 per day. Additional filter cartridges rated at 10 and 1
micron (Filterite U10AW20U and U1AW20U, respectively)
are used following the microfiltration system to ensure that
particles less than 1 micron in size have been removed. This
additional filtering is conducted in case any operational prob-
lems have occurred with the microfiltration system. The
microfiltration system, with filter cartridges, removes nearly
all particles between 0.5 and 30 microns.
The filtration system is operated automatically and re-
quires only plant air and electricity (110 volts). Each treat-
ment cycle lasts approximately 20 to 30 minutes and pro-
cesses about 440 gallons of frit-containing water. No data
were available for blowdown times, operating pressures, or
other operating parameters.
Costs
Maintenance and operating costs for this system are low.
The system only requires attention for 5 minutes every half
hour for the operator to add polymer and filter aid manually.
Valves, diaphragms, and other minor parts require occasional
replacement.
51
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Case Study C-3
DuPont Electronics
Sun Valley, California
The Component Materials Division of DuPont Electron-
ics manufactures ceramic dielectric powders used in the
multilayer ceramic capacitor industry. This case study is
based on data provided by the facility; more detailed infor-
mation describing facility operations, system performance,
and costs are not available.
Facility Operations
The ceramic powders manufacturing process produces
two liquid waste streams containing a complex array of
metal oxides and titanates. Elements with the highest con-
centrations are barium, titanium, neodymium, bismuth, and
lead. The compositions of the two waste streams vary
according to daily operations, but lead and total suspended
solids levels are typically in the range of 0.5 to 5.0 percent.
The treatment objective is to reduce the concentration of
metals to meet applicable effluent limits. Most of the metals
are in the form of suspended solids; there is no chemical or
physical pretreatment before filtration.
System Performance
The facility uses two 7-square foot Oberlin pressure
filters (model HB) to remove suspended solids from waste-
water. These two units are in two different locations 1/4-
mile apart. A single treatment unit processes 350 to 400
gallons per hour in a cycle time of 15 to 20 minutes. The two
units operate at a blowdown time of less than 5 minutes with
an airbag pressure of 120 psi.. Each filtration unit uses
Tyvek®T-980 as the filter media.
Diatomaceous earth (Superaid) is used as a filter aid.
Agglomeration is promoted with a polymer flocculent
(Praestol K122L) at a dosage of 50 ppm in one unit and 300
ppm in the other, depending on the type of waste each unit
treats. Both the filter aid and polymer flocculent are added
automatically in-line to the filters.
The effluent streams from the pressure filtration treat-
ment units satisfy Los Angeles sewer effluent limits of 5.0
ppm for soluble lead and 26.0 ppm total suspended solids.
Typical effluent characteristics are 0.2 to 0.4 ppm soluble
lead and 5 ppm total suspended solids. The effluent concen-
trations of other metals are unknown.
The moisture content of the filter cake is approximately
50 percent. The filter cake is classified as hazardous waste
because it does not meet TCLP test requirements. Therefore,
it is disposed of in a hazardous waste landfill. DuPont plans
to use ProFix in lieu of diatomaceous earth to eliminate off-
site stabilization and reduce operating costs.
Costs
Operating costs are related primarily to filtration sup-
plies. The monthly costs of Superaid, K122L polymer, and
Tyvek® T-980 are $150, $20, and $50, respectively. The
systems require approximately 1 to 2 hours of operator time
per day, including equipment cleaning.
Maintenance costs are very low. In 5 years of operation,
the two systems experienced no major downtime or repair
requirements.
52
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