United States ,
Environmental Protection
Agency
Water Engineering Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-85/096 Sept. 1985
c/ERA Project Summary
Application of Adsorptive/
Absorptive Resins and
Membranes for Toxic and
Hazardous Waste Reduction
J. Carl Uhrmacher
A study was undertaken to assess the
use of membrane separation and ion
exchange/adsorption resins for reduc-
ing or eliminating toxic and hazardous
wastes in the metal finishing and muni-
tions manufacturing industries. Data
were gathered by means of a literature
review and personal interviews with
leading researchers in the field.
The study examined the capabilities
of adsorptive and ion exchange systems
using conventional resins, and it also
evaluated the newer ion selective and
macroreticular non-ionic resins. Similar
evaluations were made for the mem-
brane separation processes based on
the use of conventional size exclusion.
ion exchange film-type membranes, and
experimental liquid membranes.
The process streams and operations
involved in the metal finishing and
munitions manufacturing industries
were studied in detail. All of the impor-
tant chemical species normally found in
aqueous solutions throughout the plants
were identified. Also documented are
other chemical and physical character-
istics of these streams such as the pH,
suspended solids, and the presence of
strong oxidizing or reducing agents.
The treatment problems encountered
in the two industries are quite different,
since the species to be removed from
the metal finishing wastes are.primarily
ionic, whereas the wastes from the
munitions industry contain mostly non-
ionic, nitrated organic compounds. Both
the membrane separation and ion ex-
change/adsorption resin systems are
evaluated relative to the specific char-
acteristics of the hazardous materials to
be removed.
This Project Summary was developed
by EPA's Water Engineering Research
Laboratory. Cincinnati. OH. to an-
nounce key findings of the research
pro/act that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
This study was conducted to assess the
state of the art of commercially available
and developing technologies for reducing
or eliminating hazardous materials from
liquid wastes generated in the metals
finishing and munitions manufacturing
industries. The study examines mem-
brane separation systems and ion ex-
change/adsorption resin systems for
purifying these industrial wastewaters.
Toxic and Hazardous
Wastes in the Metal Finishing
Industry
The metal finishing industry uses more
than 100 surface finishing and fabricating
processes that require aqueous applica-
tion and removal of metals. Wastewaters
from metal finishing processes contain
heavy metal cations that may be toxic and
anions that are also a potential hazard to
the environment. In addition to the ionic
species, organic molecules used as bright -
eners, cleaners, and chelating agents are
also present and can complicate the
wastewater treatment process. Potential
-------
pollutants in metal finishing wastes are
listed in Table 1.
Hazardous Wastes in the
Munitions Industry
The common explosives produced by
the munitions industry contain nitro
groups attached to a wide variety of
organic structures, which can be aromatic
(benzene ring type), heterocyclic (rings
containing non-carbon atoms), or ali-
phatic (straight or branched chains). The
munitions industry also produces nitrated
organic compounds of mercury and lead
that are used as primers for explosives or
propellants. Typical hazardous wastes
from Army munitions operations are as
follows:
RDX (Hexahydro-1,3,5-trmitro-
1,3,5-tnazme)
HMX (Octahydro-1,3,5,7-tetranitro-
1,3,5,7-tetrazocme)
TNT (Trinitrotoluene)
DNT (Dmitrotoluene)
NT (Nitrotoluene)
TAX (1 -Acetyl-1,2,3,4,5,6-hexahydro-
3,5-dmitro-1,3,5 triazme)
SEX (1-Acetyl-1,2,3,4,5,6,7,8-
octahydro-3,5,7-trinitro-1,3,5,7-
tetraazocine)
PETN (Pentaerythntol tetranitrate)
Tetryl (N-Methyl-N,2,4,6-
tetranitrobenzenamine)
Nitroglycerin
Nitrocellulose
Nitroguanidine
PRIMERS
Lead Styphnate Pb (C6HN3O8)
Lead Azide N6Pb
Mercury compounds
Two particular effluents from the man-
ufacture and processing of TNT (trinitro-
toluene) and TNT-containing ordnance
constitute a significant problem. Red
water is a darkly colored solution that
results from selite processing of TNT to
remove unwanted isomers and byprod-
ucts. This solution can be concentrated
and used as an additive in the paper
industry or disposed of by incineration.
Further washing of the partially purified
TNT produces the more dilute and lighter
colored solution termed "pink water."
Pink water is also produced as a result of
general cleaning and washing operations
throughout the plant when the carrying
stream has a neutral or alkaline pH and is
exposed to sunlight. LAP (load, assembly,
and pack) plants, where artillery shells
are cleaned by steam and repacked with
fresh explosives, also produce pink water.
This waste stream contains RDX and
HMX, two heterocyclic nitrated explo-
sives, as well as TNT.
The wastewaters encountered in these
two industries are quite different in
physical and chemical characteristics and
also in the type of hazard they present
relevant to the general population and to
the environment. In metal finishing, the
species to be removed are ionic and
amenable to treatment based on either
ion exchange or membrane-type separa-
tion techniques. The munitions waste-
waters contain mostly non-ionic, nitrated
organic compounds that have so far
resisted ion exchange treatment. The
various organic compounds encountered
should be able to be concentrated through
the use of reverse osmosis or even
ultrafiltration membrane systems, since
these separation techniques are based on
size discrimination. Removing organics
from aqueous streams with adsorptive
materials such as activated carbon is
quite common, and resin systems with
high adsorption capacities, such as those
Table 1. Potential Pollutants in Metal Finishing Wastes
Cations (Valence)
Cr (+3 +6)
CuM +2)
Ni(+2+3)
Sn (+2 +4)
Pb (+2 +4)
Au f+1 +3;
AgM)
Zn (+2)
Anions (Valence)
Cr207 (-2)
CNf-1 )
SO. (-2)
BFt(-1)
Clf-1)
SiOe (-2)
P207<-4)
Other Materials
Organics
Brighteners
Cleaners
Chelates
Detergents
Cd(+2]
with macroreticular resins, should have
the potential for treating munitions
wastes.
Use of Membrane Separation
Systems
Osmotic membranes have been a lab-
oratory curiosity since the 1920's, but
practical membranes were not commer-
cially available until the 1 960's. The full
report evaluates the classic thin-skinned
polymeric membranes used in ultrafiltra-
tion and reverse osmosis systems today,
and it examines dynamic inorganic mem-
branes. The full report also evaluates
processes that use ion exchange mem-
branes, such as electrodialysis and Don-
nan dialysis. Finally, the full report con-
siders potential applications of an emerg-
ing liquid membrane technology that uses
both supported and emulsion liquid mem-
branes.
Use of Resin Systems
A wide range of ion exchange/adsorp-
tion-type resins have been used in indus-
trial water purification systems over the
years. The new types of resins being
developed for both ion exchange and
adsorption applications are presented in
this report. Both microreticular and macro-
reticular divinylbenzene/polystyrene res-
ins are included. Also examined are
chelating and reductive resins that react
with the metallic ions. Finally, recently
developed ion exchange precoats are
examined for potential applicability.
Methods
Sources of Information
A wide range of publications dealing
with the separation sciences was re-
viewed to develop a list of experts from
industry, government, and academia who
would be knowledgeable in this field.
Appropriate trade publications were re-
viewed to identify companies actively
engaged in metal finishing, munitions
manufacturing, producing or supplying
membranes or membrane separation
systems, producing or supplying ion
exchange/adsorption resins or treatment
systems, or conducting research in these
areas.
Evaluation of Information
Information from these sources was
compiled to give an overall history and
general picture of the state of the art for
the different types of membrane separa-
tion and ion exchange/adsorption resin
systems. The data available on the per-
-------
formance of individual products in the
treatment of hazardous wastes from the
metals finishing and munitions manu-
facturing industries were then evaluated
Combined information from all of these
sources was then assessed to determine
the potential of these technologies in the
treatment of waste streams from the
target industries.
Results
A considerable body of data and tech-
nical information was compiled as a result
of the literature .review, telephone and
personal interviews, and visits to various
research facilities. The data are present-
ed'primarily ir> the form of tables that
describe (1) the characteristics of the
various waste streams and plating solu-
tions encountered in the metal finishing
and munitions manufacturing industries,
and (2) the performance characteristics of
specific types of membrane separation
systems, membrane materials, commer-
cial membrane modules, ion exchange/
adsorption systems, resin materials, and
commercially available resin formula-
tions.
The full report presents a complete
discussion of data available on the com-
mercial uses of these wastewater treat-
ment technologies and for the treatment
of similar aqueous solutions. In addition,
the full report reviews and evaluates the
results of advanced research projects on
the development of new or novel mem-
brane systems and resin formulations
that are potentially applicable to the
treatment of these wastes. The conclu-
sions and recommendations presented in
the report are based on assessment of the
accumulated data.
Conclusions
Treatment of Metal Finishing
Wastes
Use of Ion Exchange Resin
Technology
Ion exchange resin technology is a
mature technology for the removal of
contaminants from plating solutions, the
recovery of precious metals, and the
freshening of plating baths for reuse. This
technology is being used by both manu-
facturers and firms that collect and
rejuvenate spent solutions from small
companies. Research is being performed
by private industry and government on
process improvements in areas such as
producing more highly selective resins
and developing better removal and re-
covery techniques. The economics of
using ion exchange technology in the
treatment of these wastes varies widely
for specific applications, depending on
the type of plating system involved, the
configuration of rinses, and the configura-
tion of the waste treatment system.
Use of Membrane Technology
Reverse osmosis and ultrafiltration are
mature technologies for treating metal
finishing wastes. Zero-sludge and re-
duced-sludge systems are available and
are used extensively throughout the
industry. Reverse osmosis has a partic-
ularly high utilization rate in the treatment
of nickel plating wastewaters.
Although zirconium oxide dynamic
membranes are commercially available
and appear promising, they have not been
used to any extent in the treatment of
hazardous wastes. The newer membrane
separation systems based on liquid and
ion exchange membranes, Donnan dial-
ysis, and emulsion liquid membranes are
not sufficiently developed to assess their
potential for application to the treatment
of hazardous wastes.
The economics of using membrane
separation systems in the treatment of
these wastes generally depends on:
• the amount of water to be treated,
• the fouling index (SDI) of the water to
be treated,
• pretreatment requirements for the
wastewater before introduction to the
membrane separation process, and
• the potential for resource recovery.
Potential savings and capital payback
depend on.
• the value of recovered materials,
• the potential for reusing the treated
water in the process,
• potential reductions in sewer dis-
charge charges, and
• potential savings in sludge removal
and disposl charges.
Electrodialysis and other electrolysis
processes have been used to a moderate
degree in the treatment of these waste
streams. Supported liquid membranes
have been demonstrated in the field and
show some promise, and the combination
of Donnan dialysis with other technol-
ogies has demonstrated potential for the
treatment of these wastes. However,
insufficient data are available at this time
to assess the potential economics of these
systems in the treatment of metal finish-
ing wastes.
Of the various pollutants from electro-
plating processes, hexavalent chromium
is probably the most difficult material to
treat, since it is an anion and a powerful
oxidizing agent. Claims of successful
treatment have not been fully substan-
tiated by the data available at this time.
Treatment of Munitions Wastes
Use of Ion Exchange/Adsorption
Resin Technology
Granular activated carbon (GAC) has
been shown to be more cost effective in
the treatment of munitions wastes than
currently available macroreticular resins.
However, recent laboratory studies indi-
cate that the use of these resins in a two-
bed system has significant potential for
being more cost effective than GAC mthe
future.
Use of Membrane Technology
Very little effort has been made to apply
membrane separation technology to the
treatment of wastewaters from the muni-
tions manufacturing industry. Concern
over the potential for accumulating dan-
gerous concentrations of explosive mater-
ials has been a major impediment to
research in this area. Also, very little work
has been done on the application of
membrane separation technology for
treating the unique wastes from military
installations. Although the data available
indicate mixed results, this technology is
considered to have a high potential for the
treatment of these wastes in the future.
The full report was submitted in fulfill-
ment of Contract No. 68-03-3214 by
Carltech Associates, Inc., under the spon-
sorshipof theU.S. Environmental Protec-
tion Agency.
-------
J. Carl Uhrmacher is with Car/tech Associates, Inc., Columbia, MD21045.
Thomas J. Powers is the EPA Project Officer (see below).
The complete report, entitled "Application of Adsorptive/Absorptive Resins and
Membranes for Toxic and Hazardous Waste Reduction," (Order No. PB 85-241
776/AS; Cost: $13.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-85/096
QOOO'529 PS
CHICAGO
PROTECTION AGENCY
------- |