ASTM F1525-96

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1525 – 96
Standard Guide for
Use of Membrane Technology in Mitigating Hazardous
Chemical Spills
This standard is issued under the fixed designation F 1525; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope scales on a membrane that results in a flux reduction.
3.1.5 Langelier Saturation Index (LSI)—a method used to
1.1 This guide covers considerations for the use of mem-
determine the calcium scaling potential, that is, calcium
brane technology in the mitigation of dilute concentrations of
carbonate of a membrane at concentrations below 5000 ppm
spilled chemicals into ground and surface waters.
TDS.
1.2 This guide addresses the application of membrane
3.1.6 membrane technology—separation of the components
technology alone or in conjunction with other technologies.
of a fluid by means of a pressure gradient and a semipermeable
1.3 The values stated in SI units are to be regarded as the
membrane. The various classes of membrane technology are
standard. The values given in parentheses are for information
differentiated primarily by the size or molecular weight, or
only.
both, of rejected material. The main divisions are (1) micro-
1.4 This standard does not purport to address all of the
filtration (MF), (2) ultrafiltration (UF), (3) nanofiltration (NF),
safety concerns, if any, associated with its use. It is the
and (4) reverse osmosis (RO).
responsibility of the user of this standard to establish appro-
3.1.7 microfiltration (MF)—a pressure-driven process
priate safety and health practices and determine the applica-
whereby a contaminated liquid stream is separated using a
bility of regulatory limitations prior to use. In addition, it is the
filtration process involving a compatible membrane. Dead-
responsibility of the user to ensure that such activity takes
ended and crossflow techniques are used. Suspended solids and
place under the control and direction of a qualified person with
macromolecules are removed on the basis of size. Pore size is
full knowledge of any potential or appropriate safety and health
normally 0.1 to 5.0 μm, and operating pressures usually range
protocols.
from 20 to 350 kPa (3 to 50 psig). Membrane materials, such
2. Referenced Documents as polypropylene, polytetrafluoroethylene (PTFE), and metal
oxides, are frequently less susceptible to chemical degradation
2.1 ASTM Standards:
than those used for other branches of this technology.
F 1127 Guide for Containment by Emergency Response
3.1.8 nanofiltration (NF)—a pressure-driven process
Personnel of Hazardous Material Spills
whereby a contaminated liquid stream is separated and purified
3. Terminology
by a process involving filtration, diffusion, and chemical
potential across a compatible membrane. Divalent and multi-
3.1 Definitions of Terms Specific to This Standard:
valent species with a molecular weight above 80 are removed
3.1.1 concentrate, retentate—in reverse osmosis and nano-
as are uncharged and univalent molecules with a molecular
filtration, respectively, the portion of the feed solution that does
weight above 200. Operating pressures normally run between
not pass through the membrane is called concentrate, while the
1380 and 2760 kPa (200 and 400 psig).
term retentate is more commonly used for ultrafiltration and
3.1.9 osmotic pressure—as related to membrane technol-
microfiltration.
ogy, the pressure that must be applied to the more concentrated
3.1.2 crossflow filtration—a filtration process in which the
solution to halt flow of the solvent from the less concentrated
feed flows almost parallel to the filter or membrane surface. It
solution through a semipermeable membrane into the more
is also called tangential flow.
concentrated side.
3.1.3 flux—a measure of the rate at which the permeate (or
3.1.10 permeate, filtrate—the stream that has passed
filtrate) passes through the membrane per unit area of mem-
2 3 2
through the membrane and is therefore free of, or has a much
brane. It is reported in units of L/m /day, m /m /day, or
reduced concentration of, contaminants. Permeate is com-
gal/ft /day.
monly used for the treated water obtained from nanofiltration
3.1.4 fouling—the accumulation of unwanted deposits or
and reverse osmosis processes, while filtrate is more com-
monly used for the treated fluid obtained by ultrafiltration and
This guide is under the jurisdiction of ASTM Committee F-20 on Hazardous
microfiltration operation.
Substances and Oil Spill Response and is the direct responsibility of Subcommittee
F20.22on Mitigation Actions. 3.1.11 pervaporation (PV)—a vacuum-driven membrane
Current edition approved April 10, 1996. Published June 1996.
process applicable to the separation of liquid mixtures. During
Annual Book of ASTM Standards, Vol 11.04.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 1525
the separation, the dissolved, more volatile constituents are (AOPs). This method is recommended for dilute solutions. The
removed from a less volatile carrier stream, as a vapor, through membrane technology portion concentrates the compounds to
a semipermeable membrane and then condensed on the down- an optimum level for AOP destruction.
stream side. This energy-intensive process is still in the
5. Constraints on Usage
development stage, but it has the potential of being a very
5.1 General—Application of membrane technology to the
promising spill mitigation technology.
cleanup of spills results in the generation of two streams. The
3.1.12 reverse osmosis (RO)—a pressure-driven process in
first stream is treated and has a reduced concentration of
which a liquid stream is separated and hence purified by
contaminants, while the second is concentrated and has an
passing it over the surface of a semipermeable membrane. Both
increased concentration of contaminants. This concentrated
dissolved and suspended materials in a molecular weight range
stream must be destroyed, reprocessed, or disposed of in an
from 40 to 200 are removed, with charged species being
appropriate manner. There may also be constraints that are
removed more easily. In the case of nonpolar molecules,
created by the physical and chemical sensitivity of membranes
molecular structure “bulkiness” becomes important. Some are
and, as a result, characteristics of a membrane system must be
rejected well with a molecular weight of 60, while others with
taken into consideration whenever membrane units are used.
a molecular weight of 100 are not. Differences among mem-
These considerations are described as follows.
brane material can be very important in this aspect. This
5.1.1 Membrane Material:
process discriminates between solutes on the basis of their
5.1.1.1 The material used to construct the membrane is
ability to either (1) preferentially adsorb onto the membrane
crucial to its success. In general, for spill remediation, the UF,
pore surfaces and move through the membrane pores by
NF, and RO membranes require materials that have a good
capillary action, or (2) dissolve in and diffuse through the
temperature and pH resistance, as well as chemical stability, to
membrane. Reverse osmosis uses applied pressures between
ensure that the membrane is unaffected by the solution being
1380 and 10 350 kPa (200 and 1500 psig). As the concentration
treated. The increasing demands on the performance of mem-
difference between the solutions on the two sides of the
brane materials are exceeding the capability of organic poly-
membrane increases, the osmotic pressure of the solution
mers currently available. Consequently, inorganic membranes
increases and, in turn, the applied pressure requirement. In
have been developed in order to satisfy the need for better
general, solutions containing organic and inorganic compounds
performance. Today, high-quality organic and inorganic mem-
ranging from low ppm up to 55 000 ppm are commonly treated
branes are commercially available.
with this technique.
5.1.1.2 Inorganic membranes are classified in four groups:
3.1.13 semipermeable membrane—membranes that are se-
ceramic, carbon, metal, and polymer analog. Many develop-
lective in the components that they allow to pass through them.
ments in inorganic membranes have been achieved, but many
3.1.14 ultrafiltration (UF)—a pressure-driven process
inconveniences have yet to be overcome, such as their high
whereby a contaminated liquid stream is separated and purified
cost and low surface area/volume, which retards the expansion
by a crossflow filtration process involving a compatible mem-
of their application. In the case of organic materials, several
brane. Suspended solids and dissolved molecules in the 500 to
kinds of polymers are used that allow for the development of
300 000 molecular weight range are removed mainly on the
membranes with various properties. The following improve-
basis of size. This represents a membrane that has a pore size
ments might be noticed: lower cost, longer life time, lower
ranging between 0.0015 and 0.2 μm. Ultrafiltration uses
replacement rates, reduced chemical consumption, reduced
pressures of 105 to 1380 kPa (15 to 200 psig).
operating pressure for given flux level, use in a broader range
4. Significance and Use
of pH, higher ion rejection, easier cleaning due to effective
4.1 General—This guide contains information regarding the foulant removal and reduced biological attack, lower energy
use of membrane technology to recover and concentrate consumption, as well as reduction of capital cost. Polymeric
hazardous materials that have entered surface and ground water membranes with very high performance have been designed,
as the result of a spill. Membrane technology may be applied but their great complexity makes commercialization difficult.
alone or in conjunction with other treatment techniques, as Polymeric membranes currently on the market are available in
follows: symmetric and asymmetric configurations.
4.1.1 Different types of membrane are used in series with 5.1.1.3 Asymmetric membranes are more commonly avail-
filters to treat highly contaminated solutions reaching concen- able than the symmetric type, especially for UF, NF, and RO.
tration levels of several parts per million of organic and These asymmetric membranes are made of two layers of the
inorganic materials. same polymer. They have a thin and dense surface skin and a
4.1.2 Different types of membranes are applied in series to porous substructure that adds strength and support to the thin
treat very dilute concentrations (parts per billion level) of skin without reducing the permeate flow. The symmetric
organic and inorganic compounds. Each membrane type has configuration has a homogenous structure that provides a very
the ability to remove specific compounds, thus producing a high hydraulic resistance. Another type of membrane, very
concentrated fraction. This fraction may require final off-site similar to the asymmetric, is the thin film composite. The most
treatment but provides a significant reduction in transportation obvious difference is that the two layers are made individually,
costs due to the large volume reduction achieved. from two different kinds of polymers for better performance.
4.1.3 Membranes may be used in conjunction with destruc- The characteristics of several polymeric materials currently
tion technologies such as advanced oxidation processes available are listed in Table 1.
F 1525
TABLE 1 Features of Several Polymeric Materials
Maximum Operating Chemical UV pH Range
Polymers Hydrophilic Cost
Temperature, °C Resistance Resistance Resistance
Cellulosic CA, CN, CN/CA yes 126 fair low good fair
Nylon 6, 66 polyamide yes 135 good low good good
PVDF no 135 good medium poor good
PVDF modified yes 135 good high poor good
PTFE, film no 135 excellent high poor excellent
Polysulfone no 135 good medium good excellent
Polysulfone modified yes 135 good medium good excellent
Polyacrilonitrile . fair low
yes . fair low good fair
PAN/PVC no good fair
Polyvinyl-chloride no . fair low good good
Polycarbonate no . fair medium good good
Polycarbonate modified yes 140 fair medium good good
Polyester no 135 excellent medium good excellent
Polypropylene yes . excellent low fair excellent
Polyethylene yes . excellent low fair excellent
5.1.2 Pretreatment: sufficiently after the first cleaning procedure, the application of
5.1.2.1 Pretreatment of the feed is of primary concern when another procedure may lead to a better result. Fouling on the
membranes are used in spill cleanup. Although each membrane membrane surface is usually complex and often requires
configuration is affected differently by inorganic foulants, most several cleaning procedures successively. For example, succes-
membranes are affected adversely by oil, grease, and parts per sive cleaning with detergent and citric acid results in generally
million concentrations of inorganic compounds, including iron, more effective cleaning than either alone. Table 3 lists several
manganese, magnesium, calcium, carbonate ion, and sulphate of the common cleaning agents used for membranes.
species. Some organic species, especially at high ppm levels, 5.1.4 Flushing and Cleaning Procedures:
may also have detrimental effects and cause irreversible
5.1.4.1 Flushing—One of the most convenient foulant re-
damage to the membranes.
moval procedures is flushing. Flushing cleans the membrane
5.1.2.2 The pH of the feed solution is often adjusted to
surface using a large quantity of feedwater at low pressure. It
dissolve or precipitate inorganics, to prevent membrane fouling
is effective for cleaning membranes that have been slightly
on the membrane surface that leads to a performance decline
fouled. The general operating conditions are as follows:
(that is, lower permeate flow rate and increased pressure drop
(1) Flushing Water—Permeate (treated water),
between the feed and concentrate sides). The degree of
(2) Pressure—190 to 590 kPa (28 to 86 psi),
pretreatment required will depend on the concentration of
(3) Water Flow Rate—High flow rate but pressure drop
foulants in the feed stream, membranes used, and membrane
limited to less than 10 psi/element,
cleaning schedule.
(4) Temperature—Ambient but less than 30°C (86°F), and
5.1.3 Membrane Cleaning Agents:
(5) Period—0.5 h.
5.1.3.1 A membrane cleaning schedule will depend on the
5.1.4.2 Cleaning (Polymer Membranes Only)—Chemical
severity of membrane fouling. As mentioned above, a decrease
cleaning is ordinarily used after the flushing procedure. A flu
...