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.