United States
Environmental Protection
Agency
Industrial Environmental Researc'
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-147 Sept. 1981
Project Summary
Removal of Heavy Metals and
Suspended Solids from
Battery Waste waters:
Application of HYDROPERM™
Cross-Flow Microfiltration
Norman I. Shapiro, Han-Lien Liu, John Baranski, and David Kurzweg
Laboratory and full-scale field
demonstrations were conducted to
demonstrate the applicability of the
HYDROPERM™ cross-flow microfil-
tration system for the removal of
suspended solids, and for the removal
of suspended toxic heavy metals from
lead-acid battery production waste-
waters.
The results of the program con-
ducted at Hydronautics, Inc., Laural,
Maryland and General Battery Corpor-
ation, Hamburg, Pennsylvania show
that the system achieves virtually
complete removal of suspended solids
(the filtrate water has a suspended
solids concentration of < 5 ppm) regard-
less of the feed concentration. Lead is
typically reduced to 0.1 ppm.
The waste from the battery manu-
facturing facility is a mixture of
sulfuric acid from occasional dumping
of open-tank formation of the anode
and cathode battery plates, rinse
water from the plate washing facilities,
and various floor drains from through-
out the plant. The combined total of
daily waste production is ~ 75,000 liters
per day (20,000 gallons per day). The
waste acid and rinse water mixture is
neutralized with high calcium lime to
convert the soluble metals to a sus-
pended metal hydroxide form.
The microf iltration system is a treat-
ment process which employs a
physical principle of treatment for
suspended solids (SS) removal after
chemical precipitation. The principal
element of. the system is a thermo-
plastic tubular filter (6 mm ID) con-
structed with a controlled porosity in
the micron-size range. Relatively low
feed pressures (1.05 kg/cm2, — 15 psi)
is employed, which is of significance to
energy conservation.
The first phase of the study was to
determine the proper porosity, con-
struction material and diameter of the
tubes. In addition, studies were
conducted to optimize operating con-
ditions (pressure and velocity). The
second phase of the study involved the
design, fabrication, installation and
demonstration of a full-scale system.
Both from a flux and a filtrate quality
standpoint, the test and demonstration
programs indicated that microfiltra-
tion is effective for treating battery
manufacturing wastewaters for dis-
charge. Reuse of the permeate is
recommended for study.
Microfiltration technology wiH have
wide application in the removal of
heavy metals from such industries as
battery manufacture, metal finishing.
metal refining, and other industries
producing similar wastes.
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This Project Summary was develop-
ed by EPA 's Industrial Environmental
Research Laboratory, Cincinnati, OH,
to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Two types of filtration processes have
been widely used for removal of sus-
pended solids: (1) the through-flow (e.g.,
multimedia) filter; and (2) cross-flow
filtration (e.g., ultrafiltration and reverse
osmosis). Although they can remove
some of the suspended solids, conven-
tional through-flow filters have the dis-
advantage of requiring frequent back-
washing, since the filtered particles
continuously accumulate on, oractually
enter, the filtration barrier. Through-
flow filtration is, by its very nature, a
batch process, with the flux declining'
relatively rapidly when the driving
pressure differential across the filtra-
tion barrier is held constant.
On the other hand, in cross-flow fil-
tration, Figure 1, the direction of the
Feed flow is parallel to thefilter surface,
so that accumulation of the filtered
solids on the filter medium can be
minimized by the shearing action of the
flow. Thus, cross-flow filtration affords
the possibility of a quasi-steady state
operation with a nearly-constant flux
when driving pressure differential is
held constant.
Filtrate
Tube Wall
ttftttttmttttttmttmt'fa
ummmuuuuiuuuu
Filtrate
Figure 1. Cross-flow filtration sche-
matic.
Cross-flow filtration is intended pri-
marily for the removal of suspended
solids and is significantly different from
membrance ultrafiltration (UF) or hyper-
filtration (RO) which removes
substances on the molecular level in
addition to suspended solids.
HYDROPERM™ is a thick-walled,
porous plastic tube. Thesetubes, whose
wall thickness, inside diameter, poros-
ity, and pore-size distribution can all be
closely controlled, can be selected for a
particular wastewater so as to obtain
optimum performance. The filtration
characteristics of the tubes combine
both the "in-depth" filtration aspects of
multimedia filters and the "surface"
filtration aspects of membrane filters.
For example, while the removal of
micron- and submicron-size particles
is often difficult or impossible with
conventional gravity settling or
through-flow filters, the cross-flow
microfiltration tubes are capable of
virtually complete removal of such
particles.
This report gives a summary of the
results of a two-phase program to
demonstrate the applicability of the
microfiltration system for the'removal of
toxic heavy metals from lead-acid
battery manufacturing wastewaters
after the metals have been chemically
precipitated. This program was con-
ducted under the sponsorship of the
United States Environmental Protection
Agency's Industrial Environmental
Research Laboratory in Cincinnati,
Ohio, under a cooperative agreement to
General Battery Corporation, Reading,
Pennsylvania. The program was
initiated in August 1978 and terminated
in June 1980. The results reported in
the report include both the Phase I
laboratory test program and the Phase II
on-site demonstration of a full-scale
microfiltration system at the General
Battery Corporation plant at Hamburg,
Pennsylvania.
The two-phase program is outlined as
follows:
The objectives of the Phase I labora-
tory program were to test, evaluate, and
optimize HYDROPERM™ tubes for the
effective treatment of battery manufac-
ture wastewaters. Since a unique
feature of the tubes is that they can be
selected for optimum performance with
specific wastewaters by varying the
tube material and pore structure as well
as the system operating conditions, a
principal objective of the proposed
program was to conduct such optimiza-
tion studies.
The objectives of the Phase II program
were to design, construct, install, and
demonstrate a full-scale microfiltration
system at the General Battery Corpora-
tion plant in Hamburg, Pennsylvania.
Phase I
The wastewater used for the Phase I
laboratory program was obtained from
the General Battery Corporation plant at
Hamburg, Pennsylvania. The raw
wastewaters typically contained
-1500-1900 mg/l of lead. When
received at the Hydronautics laboratory,
the wastewater had a pH of 1.0. Toxic
heavy metals were precipitated at a
range of pH's by adding hydrated lime.
The best results in terms of lead precipi-
tation were obtained at a pH of 8.5-9.5.
After lime addition, total solids (TS)
values increased to 45,000 mg/l in the
feed, most of which were in the form of
suspended solids (SS) (40,000 mg/l).
Thirteen single-tube tests of up to 160
hours in duration were performed with
the lime-precipitated waste described
above. In all but one of the tests the
filtrate was remixed with the feed,
which resulted in a "constant concen-
tration" mode of operation. One test
was performed with increasing sus-
pended solids concentration in the feed,
with periodic removal of the filtrate from
the feed until an 85% reduction in the
total volume of the feed had been
reached. The purpose of these tests was
to provide information on filtrate flux
and quality as a function of the type of
tube and the operating conditions used.
The results of the test program
exceeded all original expectations in
terms of flux and permeate quality.
Forty-hour plateau flux levels well in
excess of 8150 Imd (200 gal/ft2-day)
were demonstrated in the Phase I
laboratory program. These represent
integrated 40-hour flux values probably
in the range of over 12,000 Imd (300
gfd). With periodic cleaning of the tubes,
fluxes in the range of 7700-9800 Imd
(190-240 gfd) were obtained after a
range of 114-164 hours of operation. In
addition, when operating at optimum pH
(—8.5-9.5) the quality of the permeate
was excellent in terms of heavy metals
removal. For example, Pb, was typically
reduced from > 10 ppm in the feed to as
low as < 0.01 ppm in the permeate with
median values in the range of 0.6-.09
ppm. Similar results were achieved for
other metals, with typical permeate
values of: 0.05 for Cu; 0.05 for Ni; < 0.1
for Zn; < 0.002 for As; and — 0.3 for Sb.
Suspended solids were typically
reduced from > 30,000 ppm in the feed
(after lime treatment) to less than 10 in
the permeate.
Phase II
Figure 2 shows a schematic of the
system designed for General Battery,
based on the results of Phase I. After the
microfiltration system had been in-
stalled and interfaced with the systerr
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Wastewater Feed
Recirculating an<$
Sludge Settling Tank
Pressure
Gauge
Level Sensor
» —
H
Cleaning
Tank
H
Main
Feed Pump
Pressure Gauge
HYDROPERM™
Modules
Permeate Line
Permeate
Collecting Tank
Permeate
Holding
Tank
Transfer Pump
Figure 2. HYDROPERM™ system schematic diagram.
components provided by General
Battery Corporation, a two-week period
of system checkout, debugging, and
operator training was initiated. The
system checkout included not only the
operation of the units but also: (1) defini-
tion of the procedure which had to be
followed with respect to the plant
wastewater neutralization process and
(2) preparation of the operational
manual based on both the laboratory
experience and upon field operation of
the unit. Thus, the manual was updated
to reflect: field operating conditions;
sampling procedures, techniques and
frequencies; and the logistics of trans-
porting collected waste feed and
permeate samples to and from the inde-
pendent analytical laboratory. Quick
turn-around of laboratory results were
critical in terms of the control of the
operational procedures to optimize the
performance of each individual module.
System Performance in the
Field
Permeate Flux and Quality
Initial daily flux values were typically
in the range of 32,600 Imd (800 gfd)
leveling off to 16,300-20,400 Imd (400-
500 gfd) after several hours of operation.
The flux was readily -restored to the
initial value by cleaning the modules for
several minutes daily with permeate.
Cleaning with dilute HCI (2%) was
practiced generally only on a weekly
basis.
At these high flux levels, production
of permeate by only one unit is in the
range of 13,200 to 18,900 liter/hr
(3500 to 5000 gal/hr) during a filtration
run of several hours duration. Typically,
a load of 94,600 liters (25,000 gallons)
of wastewater is filtered in 4-1/2 to 5
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hours by only one unit, producing
75,700 liters (20,000 gallons) of clear
permeate and 18,900 liters (5000
gallons) of sludge. The solids content of
the sludge was in the range of 20-35%
SS by weight.
Figure 3 shows the frequency of
occurrence for lead and suspended
solids contents analyzed during the field
investigation. It indicates that the
majority of the lead concentration in the
permeate is below 0.5 ppm. For properly
controlled pH adjustment in the neutral-
ization process, lead concentration can
be easily reduced to less than 0.2 ppm.
This is because most of the toxic metals
are amphoteric. They can subsequently
precipitate out in the permeate if pH
varies which can also contribute to
higher suspended solids concentration
in the permeate. The suspended solid
concentration plot shows that more
than two-thirds of permeate samples
analyzed have a concentration less than
3 ppm.
Sludge Generation
Waste sludge production is typically
about 17,000 liters (4500 gallons) for
every two days of operation, with SS
concentrations of 20-35% by weight.
The wastewater generated at the plant
during a typical two-day period is about
94,600 liters (25,000 gallons). From
these wastes, approximately 75,700
liters (20,000 gallons) of clear permeate
were produced. One tank truck load of
sludge is transported to the land-fill site
in Reading every other day greatly
reduced from the trips which the tank
truck had to make in the past (previously,
two to three trips were required daily).
The clean permeate is discharged
directly to a local stream. The reuse of
this high quality permeate water for
plant use is now under evaluation.
Conclusions and
Recommendations
au
1 7°~
1 60-
10
pH< 8
pH 8 -10
m
wOua
M B r-n il •
0<0.04 0.04- 0.07- 0.1- 0.2- 0.3 0.4 0.5- >1.0
0.069 0.099 0.199 0.299 -0.399 -0.499 1.0
Lead Concentration, ppm
S 70-
N
SL
2 60-
c
1 5°"
"I 40-
•Q
S 70-
1
i —
n „ n
Figure 3.
1-3 3-10 10-15 15-20
Suspended Solids, ppm
Pb and SS concentration in HYDROPERM™ permeate from lead-act
battery wastewater.
in the feed in the range of several
hundred ppm was typically reduced to
0.02-0.1 ppm in the permeate. Other
toxic heavy metals, such as Cu, Ni, Zn,
As, and Sb were removed with
comparable effectiveness. Although the
filtrate is discharged directly to a local
stream, the quality of the filtrate in
terms of SS and toxic heavy metals is
such that reuse is also a viable option.
Recommendations
Cross-flow microfiltration should
have broad application for the removal
of SS and suspended toxic heavy metals
in a wide range of industries, including
battery manufacture, metal finishing,
smelting and refining, and other
industries with similar wastewaters.
Economics for the concept remain to be
developed.
General
Cross-flow microfiltration is an effec-
;ive technology for the treatment of SS
in wastewaters from the production of
lead-acid batteries.
Permeate Quality
Suspended solids in the feed which
exceeded 150,000 ppm were typically
reduced to 3 ppm in the permeate. Lead
Flux
One HYDROPERM™ unit with 16.7
m* (180 ft2) of filter surface area
achieved a plateau flux value of 16,000
Imd (400 gfd), lime-treated, lead-acid
battery wastewater.
Sludge
Sludges in the range of 20-35 percent
SS by weight were regularly produced
by the HYDROPERM™ system.
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Norman I. Shapiro and Han-Lien Liu are with Hydronautics. Inc., Laurel, MD
20810; John Baranski and David Kurzweg are with General Battery Corpora-
tion, Reading, PA 19603.
Charles Darvin is the EPA Project Officer (see below).
The complete report, entitled "Removal of Heavy Metals and Suspended Solids
from Battery Wastewaters: Application of HYDROPETiM™ Cross-Flow Micro-
filtration," (Order No. PB 81-234 833; Cost $9.50. subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•h US GOVERNMENT PRINTING OFFICE, 1981 —757-012/7320
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United States Center for Environmental Research Feesfpaid"
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Agency C.ncmnati OH 45268 Protection
Agency
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