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Water Sifi
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Acidity, Alkalinity, and Phosphates:Sources and Reduction
Mr. Leon Moser
Moderator: Mr. Sam Moore
3A
SOURCES OF WASTE
ACIDITY, ALKALINITY, PHOSPHATES,
SOLVENTS, METALS, ETC.
WASTE CHARACTERISTICS FOR TEXTILE PROCESSING
Hard-to-Treat Wastes
Primary color, metals, phenols, toxic
organic compounds, phosphates
Dispersible Wastes
Print paste, lint, coating waste (especially foam),
cleaning solvent waste, still bottoms from solvent
recovery, batch dumps of unused processing mixtures
Hazardous or Toxic Wastes
Metals, chlorinated solvents, non-degradable materials,
volatile organic compounds
Hiqh Volume Wastes
High volume wastewater, wash water from continuous
preparation or dyeing, alkaline waste from preparation
(scouring or bleaching>, acidic or basic batch dye
waste, processing waste waters containing large amounts
of salt, acid or alkali
ALKALINITY/ACIDITY; pH
- Typical textile plants often have many sources
of acid or alkalis.
- Control of effluent pH can be difficult from a
process viewpoint because in many cases there is
simply no substitute for the use of alkali or
acid.
- Reuse, recovery, recycle, or pretreatment
(equalization and/or neutralization> may be the
only alternatives.
The following chart is the acid and alkali use of a
specific textile plant:
Common Acids and Alkalis and the Use of Each
pounds used per week Total #Name of chemical 1 3 4 (four weeks)2
Acetic acid 4500 3600 4500 3600 16200Alkaf low 6363 7322 6370 7260 27520A m m o n i a 0 0 0 0 0Bicarbonate 0 0 0 0 0Caustic (50%) 2460 2530 2530 3795 10815Formic Acid 0 0 0 0 0MSP 0 0 0 0 0Muriatic Acid 0 0 0 0 0Soda Ash 1700 900 600 1300 4500Sulfuric Acid 1096 369 728 661 2854TSP 900 1000 1800 2109 5800TSPP 0 0 65 0 65Water (M gal) 6.72 8.00 7.09 7.85 32.46
If used simultaneously in the above quantities, the
process waste pH would be = 10.7. Of course, in practice
this would fluctuate between wide limits within a typical
24-hour process time.
SOURCES OF ALKALINITY IN TEXTILE PROCESSING
- Removal of sizes such as CMC, PVAc, PVOH, and
PAA are normally removed in alkaline solutions. Waste
streams from this normally continuous process can be
neutralized by addition of acid. A minimum of alkali
should be used in the process.
- Scouring and bleaching of synthetics should use
a minimum of alkali. Cotton uses far larger amounts of
alkali, normally 2% to 4% of caustic (50%) on the weight
of the fabric. Neutralize or reuse these waste streams.
- Mercerization of cotton requires caustic concentrations
in the range of 20% to 30%. Caustic recovery is a necessary
economic factor with normal recovery in the neighborhood of
90%.
- Dyeing processes also contribute to the alkalinity
of waste effluent.
- Direct dyes exhaust from weakly alkaline baths
(pH 8 using soda ash).
- Fiber reactive dyes exhaust from neutral baths but
use massive amounts of salt. The reaction occurs by adding
large amounts of alkali using caustic, soda ash, silicate
and/or TSP. The pH will be generally above 1.0.
- vats and sulfur dyes are typically exhausted
from alkaline baths, the dye is oxidized.
SOURCES OF ACIDITY IN TEXTILE PROCESSING
- Nylon, silk, and wool are exhausted from weakly
to strongly acidic dyebaths (pH 3 to 7). Acids used can
be formic, acetic, sulfuric, or buffer salt mixtures.
- Basic dyes for acrylic and polyester fiber exhaust
from mild to weakly acidic baths (pH 4 to 5). Acetic acid
is normally used.
- Naphthol dyes (Azoic coupling components) are based
on the formation of a diazo salt in a strongly acid bath
(pH L3>. Also applies to developed direct dyes.
- Disperse dyes for synthetics are typically exhausted
from weakly acidic solutions (pH 4.5 to 6).
- Dyeing of blends varies such the effluents may be
acidic or alkaline.
- Carbonizing of wool’ uses a concentrated sulfuric
acid bath (20% or more conc.).
POSSIBLE REMEDIES FOR ACID/ALKALI WASTES
Possible strategies include reuse of continuous
waste streams and/or processing baths, recovery systems
for caustic and using minimum amounts of acid/alkali where
possible.
Neutralization and/or equalization of waste streams
is almost always necessary. Substitution of milder or
less toxic acids or alkalis is also advisable.
SOURCES OF METAL WASTES IN TEXTILE PROCESSING
Metals are produced from several sources in textile
processing. Most prominant among those sources are the
following:
Fibers
Incoming water supply
Plumbing (pumps, pipes, valves, etc.)
Electrolyte, acid, alkali, oxidizing and reducing agents
Dyes and pigments
Certain finishes
Herbicides, bacterocides,pesticides, etc.
Maintenance chemicals
Levels of metal-as low as > lppm are considered
significant. Overall toxicity varies with type metal, bound
or not bound.
SOURCES OF METAL FROM TEXTILE FIBERS
Metals occur in both natural and synthetic fibers.
In natural fibers, such as cotton, metals may be absorbed
from the environment during growth. Cotton fibers have
shown levels in the range 75 to 100 ppm.
In synthetic fibers catalyst used in polymerization .
or metals from other sources can also contribute.
Metals can also be found on incoming fiber occuring
from processing machinery warp size, etc.
SOURCES OF METAL FROM TEXTILE WATER SUPPLIES
Metals may occur in significant levels in a public
water supply. Copper may be added to public water systems
to prevent algae growth in tanks and ponds. Aluminum may
also be added. Interestingly, metals from influent water
may undergo ion exchange with plumbing such as lead
joints, valves, pump parts, etc., to produce lead in mill
effluent.
In general, when making process modifications or
chemical substitutions to reduce metals, textile mills
should study the contribution of influent water. Water
supplies often vary with the season so several studies
may need to be done.
SOURCES OF METALS FROM OXIDIZING AND REDUCING AGENTS
Metal containing oxidizers (such as dichromate) have
traditionally been used in textiles, especially with vat
or sulfur dyes. Also, cleaning solutions for laboratory
glassware have been chrome oxidizing agents. In general
there are a number of problems associated with the use of
chromium oxidizing agents.
1. Chrome is not easily rinsed from glassware and
may be detrimental to microbiological work.
2, Chrome is toxic in the aquatic environment.
3. Chrome is highly toxic to bacteria present in
sewage treatment.
Pollution source reduction strategies include:
1. Switch to non-dichromate oxidizers such as
peroxide or periodate. These are normally readilly
available, very suitable and produce non-toxic wastes
when properly treated.
2. Never dispose of dichromate solutions in a
sanitary sewer.
Sometime zinc stabilized sulfoxylate reducing agents
may be used. These can be substituted with sodium hydrosulfite.
SOURCES OF METAL FROM TEXTILE FINISHES
Some finishes contain orgametallic compounds.
These include water repellents, flame retardants, anti-
fungal and anti-odor (bacteriocides). Metals contained
in these include antimony, tin, and zinc. Many times
because of the unique properties of the particular finish,
no good substitute is available.
The following steps can be taken to reduce the
amounts of these metals.
- Do not dump leftover mixes in waste streams.
- Make up only the exact amount of finish needed.
- Store and save all excess to use on future runs
where possible.
- Do not mix necessary waste with routine wastes
from processing.
SOURCES OF METAL FROM MAINTENANCE CHEMICALS
This source is often overlooked by textile companies.
Companies in general should go through a routine approval
procedure before using any maintenance chemical. Once
approved, consistent quality control checks on the incoming
chemical should be performed.
Miscellaneous chemicals which often contribute to
metal content in waste waters include herbicides to control
grass and weed around certain storage areas and photographic
chemicals which may be used in design photography or screen
making in a printing plant.
SOURCES OF ORGANIC SOLVENTS IN TEXTILE PROCESSING
These materials can be used in either normal non-
aqueous forms or in acueous emulsions (such as textile
printing thickeners). Solvent scouring operations are the
most typical use of non-aqueous solvent (like
perchloroethylene). Typical ranges must recover and
reuse solvent to be economically profitable. A classic
example of how polluting an operation can be is the
following:
A typical solvent scouring range running at 70 yds/min.
with a 93% recovery rate of solvent will dump nearly 1 ton
of solvent per day per range into waste streams.
Typical solvent emulsions include scouring agents,
dye carriers for synthetic fibers and printing thickeners.
In the case of dye carriers, the materials may exhaust into
the fiber and later are evolved in driers as volatile
organic compounds (VOC's). These carriers include:
Methyl naphthalene
Trichlorobenzene
Chlorotoluene
Ortho dichlorobenzene
Perchloroethylene
Butyl benzoate
Biphenyl
Care should be taken not to spill, dump, or leak
the concentrated chemicals into waste streams. Also
sometime substitution or process modifications is possible.
For instance, in dyeing polyester, oftentime jet machines
need no carrier at all. A non-polluting surfactant may
be all that is necessary to assure uniform dyeing, deep
penetration of dyes and levelness.
Solvents can also be used as machine cleaners,
parts deqreasers, and in laboratory extraction
procedures. Never dispose of these materials in a
sanitary sewer. Use solvent recovery or disposal
containers. Solvents should be separated before recovery
and/or disposal. Separate waste containers should be
available for:
Chlorinated solvents
Non-chlorinated solvents
Water free oils
As a strategy, often chlorinated solvents such as
methylene, chloride, perchloroethylene, or chloroform
in both the laboratory or in processing can be
substituted for by using other solvents such as
xylene, toluene, or freons.
Phosphates
Source
M S P
TSPP
Phosphoric acid
HexaphosCalgon
PhosphateEsters
PhosphatesPhosphonamides
buffers,
builders for scouring,
water conditioners,
surfactants, and
flame retardant finishes.
Phosphate Substitutions
se
acid salt, pH adjustment
alkali, water conditioner
strong acid, pH control
alkali, builder for detergents
Water conditioner
Surfactants, scouring
Flame retardants
Substitute
acetic acid
soda ash
HCl
Caustic or soda ash
E D T ASilicate
Ethoxylates orquaternaryamines
varies
Vat Blue 29 ....................................................... Cobalt
Pigment Blue 15 ................................................ Copper
Ingrain Blue 14 ................................................. Nickel
Ingrain Blue 5 ................................................... Cobalt
Ingrain Blue 13 ................................................. Copper
Direct Blue 86 .................................................... Copper
Direct Blue 87 .................................................... Copper
Pigment Blue 17 ................................................ Copper, Barium
Acid Blue 249 .................................................... Copper
Ingrain Blue 1 ................................................... Copper
Pigment Blue. 15 ................................................ Copper
Pigment Green 37 .............................................. Copper
Pigmgt.nt Green 7 ............................................... Copper
Ingrain Green 3 ................................................ Copper
Solvent Blue 25 .................................................. Copper
Solvent Blue 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Copper
Solvent Blue 55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Copper
Reactive Blue 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Copper
Permanently mark the date that
the drum was opened, as a visual
verification that the test was
done, and as an aid in detecting
aged chemicals.
Check pH with meter or paper and
record.
Check viscosity with Zahn cup
arid record.
Check density with hydrometer
and record.
Note color and clarity visually and
r e c o r d .
Note odor and record.
Check index of refraction with
hand-held refractometer (for clear
liquids) and record.
Compare data to previous history
and vendors’ standard values.
Enter the data on a control chart
for display.
K e e p c a r e f u l l y d o c u m e n t e d
records for each chemical on a
long term basis.
Electrolyte
-Common salt (NaC1)
-Salt brine (-20% NaC1 solution)
-Glauber’s Salt anhydrous
(Na2S04)
-Glauber’s Salt heptahydrate
(Na 2S0 4.7H 20)
-Glauber’s Salt decahydrate (Na2
S O * 1 0 h 2 0 )
-Epsom Salt (Mg SO4 - rarely
u s e d )
Electrolyte
acid or alkali content, by pH and
alkalinity of a 10% solution;
insoluble material, by filtration;
cleanliness (trash), by visual
inspection;
C a + + a r i d M g + + , b y m e t h o d s
described in another part of this
series8;
iron, copper, manganese and
other heavy metals, by methods
of water analysis*;
organic-extractable materials.
SPECIALTY Q C
- REDUCE RISK (ECONOMIC>
- ABATE POLLUTION
- REDUCE HAZARDOUS WASTE
- IMPROVE WORKER SAFETY
ALWAYS !
LET 'EM KNOW YOU'RE CHECKING
EVERY DRUM
REDUCING AGENTS
- hydro (Na2 S2 O4 ' 2H20)
- thiosulfate (Na2S203)
- bisulfite (NaHSO3
- sulfoxylate/formaldehyde
OXIDIZERS
Peroxide (Hydrogen peroxide)
Bleach (Hypochlorite, bleaching powder, Chlorine,
Chlorite R(Textone , Sodium chlorite)
Perborate
Permanganate
Dichromate
Periodate
Oxidizer React With Titrant Indicator
Peroxide -- Permanganate Pink color of excesspennangante
Hypochloritc Arsenite Iodine Starch/iodine complex
Chlorite Iodine Thiosulfate Starch/iodine complex
Perborate Iodine Thiosulfate Starch/iodine complex
ACID/ALKALI
TITRATE FOR STRENGTH
METAL CONTAMINATION
(NEUTRALIZE & TEST AS H20)
SEDIMENT/SUSPENDED MATTER
ACIDS
. ORGANIC
ACETIC
FORMIC
OXALLIC
. MINERAL
MURIATIC
SULFURIC
PHOSPHORIC
. ACID SALTS
MSP
SOME OF THE MORE COMMON TYPES OF PROCESSINGASSISTANTS INCLUDE:
PREPARATION: WETTING, SCOURING (SOLVENT ANDSOLVENT-FREE>, DESIZE AUXILIARY, CHELATE,EMULSIFIER, ETC.
DYEING: DISPERSANT, LEVELER, LUBRICANT,EMULSIFIER, WETTERS, RETARDER ANDACCELERANT, SOFTENER, COMPATIBILIZER,CARRIER, BUFFER, ACID, ALKALI,ANTIMIGRANT, DEFOAMER, ETC.
FINISHING: ANTIMIGRANT, RESIN, CATALYST, SOFTENER,BUILDER, ETC.
- COST AND PERFORMANCE
- HAZARDOUS WASTE CHARACTERISTICS (IGNITABILITY,
TOXICITY, CORROSIVITY, REACTIVITY, FLAMMABILITY>
- PRIORITY POLLUTANT STATUS (THE LIST Of 126)
- AVAILABILITY OF SAFER ALTERNATIVES
- BIODEGRADABILITY
- HEAVY-METAL CONTENT
- POTENTIAL FOR ACCUMULATION IN THE FACILITY
- POTENTIAL FOR RELEASE TO THE ENVIRONMENT
- HAZARD POTENTIAL WHEN MIXED WITH OTHER CHEMICALS
- PROPOSED MANNER OF USE
- ULTIMATE FATE OF THE CHEMICAL
- HAZARD POTENTIAL TO THE CUSTOMER
- WHO WILL HANDLE THE CHEMICAL
- HOW WILL IT BE USED (MIXED WITH, CONCENTRATIONS>
- DOES THE USER HAVE THE PROPER SAFETY EQUIPMENT
- WHAT ARE THE SPILL PROCEDURES, INCOMPATIBILITIES,
ETC.