United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S2-84-147 Oct. 1984
Project Summary
Closed Cycle Textile Dyeing:
Extended Evaluation of Full-Scale
Hyperfiltration Demonstration
Craig A. Brandon
Hyperfiltration (HF) is a membrane
separation technique that has been
used successfully to desalinate natural
water. Because energy, process chemi-
cals, and water are discharged from
industrial processes in large quantities,
recycle has been studied in a series of
government sponsored research
projects. Research results led to the
current project of joining a full-scale HF
system (with operating dye range) to an
integrated production unit. The dye
range is a multipurpose unit with a
variety of effluents from the
preparation and dyeing of a variety of
textile fabrics.
High temperature membranes of
hydrous zirconium oxide and
polyacrylic acid, dynamically formed on
porous sintered stainless-steel tubular
supports, were installed as a
demonstration unit. Over 2 million m of
fabric was produced with recycled
water. Two 4000-m lots of fabric were
produced with the recycled chemical
concentrate. The demonstration pro-
ject was extended to further study and
develop the recycle of the chemical
concentrate.
Demonstration results indicated a
positive rate of return, with savings
from recycle more than offsetting
capital and operating costs. The actual
payout time depends primarily on the
value of the chemicals and the practi-
cality of their recycle.
This report describes the HF system,
gives data from several chemical
recycle tests, and discusses HF as a dye
recovery technique. The HF system is
set aside for possible future use when
economic and regulatory requirements
change. In this off-line configuration,
privately funded studies of reuse and
membrane performance are continuing.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory, Research Triangle
Park. NC. to announce key findings of
the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The technical feasibility of using hyper-
filtration (HF) to renovate textile
wastewater for direct recycle was shown
in a series of research projects conducted
as part of a cooperative program between
the textile industry and the U.S. EPA,
beginning in 1972.
The current project demonstrates, at
full scale, the use of HF with a production
dye range. This project is funded by a
cooperative agreement between the EPA,
the Department of Energy, the Depart-
ment of the Interior, and La France
Industries, a Division of Riegel Textile
Corporation.
The wide scale implementation of HF to
recycle hot process effluents would have
a large impact on pollution abatement.
The cost of achieving this pollution
abatement with HF will be offset by the
combination of savings from the
simultaneous recovery of energy, water,
and chemicals. If subsequent waste
treatment is required, instead of reuse,
for all or a portion of the chemical residue,
the cost of this treatment will probably be
less because of the volume reduction
achieved by HF.
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The renovation and recycle of hot
process water has been demonstrated.
This report summarizes information
about chemical reuse obtained during a
12-month extension of the original
project period. Some of the background
material included in the final report on
the initial phases of the project is
included here for the reader's conveni-
ence.
Hyperfiltration
Hyperfiltration is a membrane
separation process Operating on the
principle of selective diffusion through a
semipermeable membrane, achieved by
pressure differential. Since the
separation is achieved without a change
of phase, membranes are inherently
energy efficient. An optimized single-
pass arrangement, which requires no
recirculation of any concentrated
material, utilizes about 4 Btu/lb* of water
passing through the membrane. The
energy used is generally electrical energy
to operate the pumping system. Convert-
ed to the equivalent thermal basis of
10,500 Btu/kWh, this would be about 12
Btu/lb of permeate produced. Change-of-
phase technologies, such as freezing and
evaporation, require 4 to 40 times as
much energy per pound of water separ-
ated.
Initial interest in membrane separation
was largely directed to desalination of sea
and brackish water. Attempts to utilize
the technology in industrial situations
encountered limitations dictated by
temperature and composition of the
typical individual waste streams. The
innovation of zirconium oxide/polya-
crylic acid (ZOPA) membranes, dynami-
cally formed on sintered stainless-steel
tubes, relaxed many of the limitations.
Dynamically formed membranes can
operate under a wide range of corrosive
conditions at high pressures and tem-
peratures, are able to withstand high
suspended and dissolved solids, and are
not subject to bacteriological attack.
These high temperature membranes are
utilized in the current HF demonstration
system.
Previous Studies
Three previous studies led to this full-
scale demonstration. The first study,
begun in 1972, involved the pilot-scale
separation of composite wastewater from
"Readers more familiar with the metric system are
asked to use the following conversion factors 1 Btu
= 1 055 kJ, and 1 lb = 0454kg.
a beck dyeing process and full-scale reuse
of HF permeate and concentrate at this
site. Polyamide (hollow-fine fibers), cellu-
lose acetate (spiral and tubular), and
hydrous Zr (IV) oxide-polyacrylate mem-
branes were used. Eighteen production
dyeings involving a total of 1348 m of
cloth were carried out in a production dye
beck.
The purified permeate water was a
satisfactory substitute for normal process
water in all production dyeings for water
recoveries ranging from 75 to 90%.
Membranes used in the renovation of the
wastewater had conductivity rejections
of 65-95% and color rejections of 86-
>99%.
It was also technically feasible to reuse
all the concentrate. In 11 production
dyeings, over 700 m of cotton velour
fabric was produced, graded as first
quality, and sold commercially. In 10
tests, standard shades were produced
with an average dyestuff savings of 16%.
A second study involved composite
wastewaters (obtained from the several
processes occurring in a dyeing and
finishing plant), separated by HF, and the
cumulative permeate and concentrate of
90% recovery tested for reuse as process
water in laboratory dyeing. Precast and
dynamically formed membranes were
used at eight dyeing and finishing plants.
The processes encountered were: dyeing
of nylon using pre-metalized dyes, dyeing
of acrylic fabric using basic dyes, and the
scouring, de-sizing, and dyeing of cotton
and polyester. In all cases the product
water was acceptable for replacement of
process water as determined in laboratory
dyeings using standard production evalu-
ations. Analyses indicated higher COD
and dissolved solids and lower concentra-
tions of metals in the permeate water
than in the fresh plant-process water.
The concentrate from the pre-metalized
dye process was suitable for dyeing very
deep shades when appropriate dyes were
added. Laboratory dyeing tests using
concentrates from the other processes
were unsuccessful. Perhaps this result is
not surprising because the concentrates
were obtained from a feed containing a
composite of effluents from the plant
process and not from a single process.
The first two studies dealt with renova-
tion of the composite wastewater from
the dyeing and finishing plants. Because
of the obvious advantages for chemical
reclamation and energy conservation, a
third study evaluated HF for direct recycle
of unit process effluents. Five major water
and energy consuming preparation and
dyeing processes were studied with high
temperature HF membranes. The perme-
ate produced by the membranes was
again found to be universally usable as
process water. I n some cases the reuse of
the concentrate from the individual pro-
cess effluent streams was estimated to
be practical.
Energy Related Problems
About 2 trillion gal. of hot water is
discharged by industry each year. Liter-
ally, about 6% of all the energy consumed
by industry goes down the drain. Much of
this hot water is "contaminated" with
chemicals and other dissolved or sus-
pended material, which not only consti-
tute a hazard to the environment, but
represent an additional "waste" of mate-
rials which requires substantial energy to
produce or replace. Additionally, much
energy is expended by industry to remove
water from the industrial waste stream to
achieve desired levels of chemical con-
centration to permit reuse, or to reduce
the volume of materials to be stored, pro-
cessed, or transported.
Method of Study
This project was conducted using exist-
ing HF equipment with production lots of
fabric selected to represent the value of
chemical recycle. The amount of dye in
the HF concentrate was evaluated by
using standard production equipment to
dye cloth samples for which shade depth
was measured. Shades were matched
manually to develop the formulation to be
used in the initial full-scale reuse tests.
Late in the project period, automatic color
sensing equipment and a computer were
used to calculate shade matching formu-
las.
Regularly scheduled production was
accomplished with recycle dyes and
chemicals after additions were made to
the formulations to achieve color match-
ing. Standard finishing and inspection
procedures were followed with the mate-
rial produced in these reuse tests.
Results
For 36 months, a production size HF
unit has been integrated with a manu-
facturing dye range. Full-scale recycle of
hot wash water from a dynamically
formed ZOPA membrane HF system has
been utilized with the production ol cotton
velour fabric. More than 2 million m of
fabric has been washed with recycled
water with no significant effect on fabric
quality.
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Reuse of dyes and chemicals were
shown in laboratory and full-scale pro-
duction to be technically feasible (Table
1). Full-scale production reuse tests were
conducted producing first quality goods
from mixtures of dyes recovered from a
series of production lots as well as from a
single production lot. The economics for
La France are not attractive because of
the relatively low cost of direct dyes that
comprise the major percentage of produc-
tion there. A color matching computer
was used to demonstrate the procedure
for developing formulations for color
matching.
For more than 40 months, ZOPA mem-
branes have remained stable with respect
to rejection. It has been demonstrated
that the stainless tubing can be complete-
ly stripped and that new membranes can
be formed in-situ. Membrane cleaning
methods have been developed for both
the basic and direct dye formulations in
use at La France. Results of a series of
operation and cleaning sequences are
shown in Figure 1. However, the produc-
tion of permeate has been limited (by
membrane fouling) to about 50% of the
design capacity.
Disposal, as distinct from reuse, of HF
concentrate was studied. The technical
feasibility of incineration after further
concentration by HF and drying was
demonstrated. Thus a method of complete
on-site disposal was shown to be techni-
cally feasible. At La France, the HF
concentrate is treated in the biological
treatment system with no apparent prob-
lems.
Conclusions and
Recommendations
The experimental results and economic
projections indicate that the most favor-
able situation for the application of HF is
where there are simultaneous and signif-
icant benefits for water, energy, and
chemical recovery and where significant
waste treatment costs can be abated by
reuse volume reduction.
For example, a new plant in a city in a
water-short region dyeing nylon velour
would findHF very economical. The value
of water and the charges for sewage
could be 2 to 5 times that at La France.
The value of pre-metalized dyes could be
5 to 10 times the direct dyes normally in
the wash water at La France.
The value of direct dyes and the cost
saving in water and waste treatment at La
France are not sufficient to justify con-
tinued operation of the HF system on a
commercial basis. The HF unit has been
Table 1. Test Dyeing with HF Concentrate Mixed with About Equal Portions of Excess Dye
Liquor
Date Test Mixture
Standard Shade Produced Results
8/8 single lot, c/6/7"; blue; 450 m
8/15 direct dye, c/686
8/15 mixture of basic* lots c/'685; slate; 550 m
c/2362, 6642. 7752.
6772, 715, 6692
8/19 mixture of direct dye c/334; brown; 4500 m
lots c/3255. 325
8/25 single lot of direct c/686; slate; 4500 m
dye, c/686
9/2 single lot of direct c/686; slate; none
dye, c/686
9/21 mixture of direct dye c/434; rose, none
lots, c/3255. 434.
4375
10/18 single lot of basic dye c/2362; rust; 450 m
c/2462
lab scale color matching; crock test
acceptable; 50% aux. chemicals;
7 production adds
lab scale color matching, crock test
acceptable; 50% aux. chemicals,
2 production adds
lab scale color matching; crock
test acceptable; 50% aux. chemicals;
computer calculated dye adds; HF
cone, diluted 2 to 1 before dye
addition
lab scale color matching; crock test
acceptable; HF cone, diluted;
computer calculated dye adds; 50%
aux. chemicals; 2 production adds
computer calculated dye adds; HF
cone, diluted 2 to 1
computer calculated dye adds
lab scale color matching, crock test
acceptable; 50% aux. chemicals,
off-shade reduction required redye
"c/xxx indicates production color that is achieved by proprietary mixtures of dyes and other
chemicals.
"fias/'c dye refers to proprietary mixtures of basic and other dyes and appropriate chemicals for
acrylic fiber fabric.
placed on standby, available for possible
future use when economic and regulatory
requirements change, particularly in the
area of color removal.
The usefulness of the results of the
demonstration project can be enhanced
by further development of techniques for
chemical reuse and further development
of techniques to improve performance of
the hyperfiltration unit.
This full-scale installation can be used
in the future to:
1. Continue full-scale reuse testing of
HF concentrates combined with
unspent dye liquors; and
2. Develop and evaluate new mem-
branes for lower fouling and for
better rejection of basic dyes.
It is improbable that reuse of 100% of
the HF concentrate will ever be practical
due in part to scheduling and storage
difficulties. However, this full-scale pro-
duction unit could be used to further
study HF concentrate disposal. HF concen-
trate is a new form of industrial effluent:
its disposal, because of its small volume
and high concentration, may be amenable
to processes not normally employed for
waste treatment.
Results of this demonstration of high
temperature dynamically formed HF mem-
branes on reuseable porous stainless-
steel tubes are applicable to many indus-
trial situations. Porous sintered metal,
dynamically coated with select mem-
branes, can be widely applied to hot
(>100°C), corrosive, and suspended-
solids-laden industrial effluents. The
dynamic formation technique is inherent-
ly versatile, pemitting in-situ membrane
replacement and the use of a wide variety
of membrane materials. Added research
in membrane tailoring for selected indus-
trial categories would be of value.
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3'
I
2 -
D
D
D
* A
XO
<
•
a a
Wash Water
A Direct Dye. Day 1
O Direct Dye. Day 2
9 Direct Dye. Day 3
D Direct Dye, Day 7
X Direct Dye, Day 11
a D
Time, hours
Figure 1. Membrane flux versus time after exposure to waste water. (Membranes were
washed with 85°C water before each day's operation. Before days 1, 7, and 11,
chemical washing for direct dye waste was employed.)
C. A. Brandon is with Riegel Textile Corporation, La France. SC 29656.
Robert V. Hendriks is the EPA Project Officer (see below).
The complete report, entitled "Closed Cycle Textile Dyeing: Extended Evaluation
of Full-Scale Hyperfiltration Demonstration," (Order No. PB 85-106 797;
Cost: $10.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22J6J
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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-tt US GOVERNMENT PRINTING OFFICE. 1984—559-016/7843
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