WASTE TREATMENT PROCESSES, METHODS AND TESTS

FOR DISPOSAL OF CUTTING FLUIDS

MILACRON A World Leader in Munufucturing Technologies

24 August, 2001

John Calcagni North Carolina DENR 1639 Mail Service Center Raleigh, NC 27699-1639

Re: Copyright Consent

Dear Mr. Calcagni:

Thank you for your letter to John Kline. I have enclosed a terminable copyright consent in response to your request concerning Milacron’s 1978 publication entitled “WASTE TREATMENT PROCESSES, METHODS AND TESTS FOR DISPOSAL OF CUTTING FLUIDS”. Unfortunately, the contact information in the original is no longer correct. Therefore, I request that in preparing the “pdf” file for posting at your website, the information from the original be obliterated or deleted and the following correct contact information be added:

Technical Services Department Consumable Products Division Milacron Marketing Company 3000 Disney Street Cincinnati, OH 45209

Telephone: (51 3) 458-81 99

Any notes of attribution for the publication appearing at your website are to name Milacron Marketing Company, rather than Cincinnati Milacron Co.

Should you or your associates have any questions concerning the enclosed, you may contact me at ((513) 487 5980).

m e g a rd s

enc

Milacron Inc 2090 Florence Avenue Cincinnati, OH 45206-2425 Tel 513/487-5000 Fax 513/487-5057

Milacron Marketing Company

COPYRIGHT CONSENT

Milacron Marketing Company hereby consents to reproduction of its 1978 publication entitled “WASTE TREATMENT PROCESSES, METHODS AND TESTS FOR DISPOSAL OF CUTTING FLUIDS” (hereinafter “Publication”) by North Carolina Department of Environment and Natural Resources, having offices in Raleigh, North Carolina (“NCDENR”), in conjunction with the US Environmental Protection Agency’s Waste Reduction Resource Center. This consent expressly includes consent for “posting” a copy of the Publication at the NCDENR website(s) from which further reproduction will be permitted by visitors to those website(s). No consent is hereby granted for posting of the Publication at any website not owned or controlled by NCDENR.

NCDENR shall conform any attribution for the Publication appearing at its website(s) to the following:

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NCDENR shall modify the content of the Publication to correct the contact information appearing at its website(s) in accordance with the following:

Technical Services Department Consumable Products Division Milacron Marketing Company 3000 Disney Street Cincinnati, OH 45209

Telephone: (51 3) 458-81 99

This consent is given free of any charge whatsoever. In the event it is discovered that the Publication has been posted by third parties who have duplicated the derivative thereof posted by NCDENR, Milacron may terminate this consent and NCDENR shall, promptly on notice of such termination, remove the Publication from all of its website(s).

For MapxqMarketing Company

I

WASTE TREATMENT PROCESSES, METHODS AND TESTS

FOR DISPOSAL OF CUTTING FLUIDS

Copyright 1978 Cincinnati Milacron Co.

Table of Contents

Page No. -

INTRODUCTION ..................................................... D,v

Chapter 1 WASTE TREATMF" PROCESSES .............................. D,1,1

Batch Treatment Continuous Treatment Bleed- in

Chapter 2 WASTE TREATMENT METHODS ................................ D , 2 , 1

Chemical Waste Treatment Acid-Alum Ferric Chloride, Ferric Sulfate, 6 Other Inorganics Polyelectrolytes Polymer-Inorganic Combinations Treat or Haul Away

Biological Waste Treatment Aerobic Systems Anaerobic Systems

Physical Waste Treatment Incinerat ion Evaporation-Distillation Filtration Ultrafiltration Reverse Osmosis Centrifagation Activated Carbon Waste Hauling Recycle-Recovery

Chapter 3 WASTE TREATMENT TESTS FOR DISPOSAL OF (XJTI'ING FLUIDS ... Biochemical Oxygen Demand Chemical Oxygen Demand Oil Grease, Freon Extraction, etc. Suspended Solids Total Solids Acid Anions Heavy Metals Phenols Surfactants PH

Chapter 4 CIKOOL TECHNICAL SERVICE IN WASTE TREATMENT ........... D,4,1

INTRODUCTION

Proper care of cutting fluids is important if the maxi” benefits of using water-based products are to be obtained. a sound, economically justifiable policy and certainly the first step of any waste management program.

Prolonging cutting fluid life is

While prolonging the life of a cutting fluid is possible, extending it in- definitely is not. Eventually, it will have to be treated and disposed of as a waste. methods are continually changing to meet the effluent limits. Disposal is an added expense to the manufacturing process and therefore should be controlled in terms of the need and frequency of dumping cutting fluid as well as the disposal method employed.

Cutting fluid wastes are as varied as they are numerous. components reflect not only their original makeup, but also the operations and conditions of their use. higher percentages of machine tool lubricating oils and/or suspended solids (dirt) than they do cutting fluid.

Dilution was once regarded as sufficient treatment and most wastes were disposed of by emptying them directly into the nearest sewer or stream. With the advent of the Environmental Protection Agency (EPA) , such prac- tices are being restricted and slowly brought under better control. To understand the objectives of waste treatment it is important to realize that there are few stock answers for every problem and each situation demands individual attention.

The science of waste treatment is new in that its goals and

Their chemical

In fact, many cutting fluid wastes contain

Spent cutting fluid is mostly water--usually over 90%. But, in treating it we may generate large amounts of gelatinous solids, release noxious gases, or create problems that are not obvious at first. Some cutting fluid components, notably oil, are recoverable but reuse is not always practical, depending on the type and degree of contamination.

Pollution laws are directed at the user. This, however, places an in- direct responsibility on the manufacturer of a cutting fluid to avoid the use of known pollutants such as polychlorinated biphenyls (PCB’s) and heavy metals.

The long-term goal of waste treatment legislation is the complete elimi- nation of pollution. The cost of complete control is exhorbitant and such control is rarely practiced except in isolated instances. Yet, the benefit of exercising some control over environmental contaminants is worthwhile--a cleaner environment.

Chapter 1

WASTE TREATMENT PROCESSES For our purposes, waste treatment processes can be divided into three categories independent of the methods of treatment used.

Batch Treatment Since cutting fluids from individual machines and central systems are disposed of by emptying the whole system at one time, "batch treatment" is often the most logical mode of disposal. This method implies segregating the waste cutting fluid from other plant waste and treating it by itself, releasing each batch as it is "broken" into solid, oil, and clean effluent phases. treatment because of its versatility.

This is probably the most widely applicable method of waste

TYPICAL CHEMICAL BATCH PROCESS pI flChemIca1 aids lor coagulation and flocculation

0 incineration ~ , ~ ~ t

1 Effluent 0

tree 011 separation

Flotation Air

For removing suspended solids

Fig. D1-1

Continuous Treatment Continuous treatment of a segregated waste is the major alternative to batch treatment. ment unit, the emulsion broken, and released in an ongoing process.

Here, the oily waste is constantly fed into the treat-

TYPICAL CHEMICAL CONTINUOUS PROCESS Chemical aids lor coagulation and f locculation

From Plant via

I Eftluent - Sludge iw'? For removing

suspended soltds

Fig. D1-2

Bleed- in For plants where large volumes or a variety of materials are processed daily, the "bleed-in'' method of odd-lot waste disposal can be a logical solution. oily waste. ment unit at a prescribed rate. cost-free treatment procedure if capital equipment is available and already in use.

At most this requires a tank of sufficient volume to hold the

In most cases this amounts to an almost The oily waste is then pumped directly into the waste treat-

Combinations of the foregoing types of waste handling are commonplace to the point that they are rarely seen in pure form. Batch treatment lends itself best to cutting fluid waste disposal and is therefore recommended.

Chapter 2

WASTE TREATMENT METHODS

Chemlcal Waste Treatment

Mst prevalent of all forms of waste treatment is the addition of chemicals which change the nature of the liquid waste. Inorganic and organic chemi- cals are used in drinking water clarification, industrial waste disposal, and sewage treatment.

Some of the chemical treatment methods in general use are:

ACID -ALUM

The simplest and best understood method of waste treatment is acid-alum treatment. 4.0 or lower, alum or hydrated aluminum sulfate is added and mixed, and the pH is raised slowly, with slow stirring by the addition of caustic. As the pH is raised above 4, the alum precipitates, i . e . , comes out of solution as a solid.

Briefly, the waste is acidified with sulfuric acid to a pH of

Small particles of aluminum hydroxide agglomerate, forming floc particles which sweep through the partially clarified water and attach themselves to other particles. This sweeping action, combined with electrostatic charges and absorption of oil into the floc, clarifies the wastewater.

Floc is removed by sedimentation (settling) or flotation and the clarified effluent discharged to the sewer or is fed to additional (secondary) treat- ment. degree of clarification, the effluent may be suitable for direct discharge to a stream or waterway.

Depending on applicable federal and local regulations and on the

Sulfuric acid is preferred but others including nitric, hydrochloric, or solid sulfamic acids work as well in most applications. sulfanilic acid is used to remove nitrites whenever this is necessary. Variations of the basic acid-alum method include neutral-pH alum-caustic treatment or alum first, then acid and neutralize. Lime, limestone, potash, and soda ash have all been used to neutralize acidic solutions in waste treatment, depending on their expense and availability relative to sodium hydroxide.

Sulfamic acid or

To insure proper waste treatment, laboratory or bench scale tests are run before treatment to determine the approximate dosages of each chemical required. acid-alum and other chemical breaks because it is repeatable and easy to perform.

Jar testing is the standard industrial method for pretesting

FERRIC CHLORIDE, FERRIC SULFATE, 6 OTHER INORGANICS

Aluminum sulfate is only one of many inorganic chemicals which precipitates (forms a floc) as pH is raised. aluminate, or magnesium chloride are often used instead. Sulfuric acid is most often used when a sulfate compound such as aluminum sulfate or ferric sulfate is used because of the synergistic common ion effect. acid may be used for the same reason with ferric chloride or magnesium chloride as a flocculant but is rarely employed because it is less effec- tive than sulfuric acid.

Ferric chloride, ferric sulfate, sodium

Hydrochloric

POLYELECTROLYTES

Synthetic organic compounds have become generally accepted alternatives to inorganic chemical waste treatment. Modern polymer chemistry provides an unlimited selection of charged, high molecular weight mlecules listed as emulsion breakers, flocculants, coagulant and settling aids.

Polyelectrolytes, or polymers, act by several mechanisms. Most spent cutting fluids are anionic, that is, they contain negatively charged molecules and solid particles. suspended in the fluid. Neutralization of these charges by the high molecular weight cationic (positively charged molecules) coagulants and settling aids promotes agglomeration of solids into settleable particles. Once floc has formed, the mechanical sweeping action and absorption found in inorganic flocculation occur, further clarifying the effluent.

Particle charges help keep the particles

Emulsion breakers or deemulsifiers have been widely used in the petroleum industry and may soon be applied to oils-carrying cutting fluid waste. They are not floc formers and have the advantage of producing a clear oil layer which can be skimmed off the wastewater. Deemulsifiers are most successful with anionic wastes.

Polyelectrolytes have several advantages over inorganic flocculants: they are used in neutral and slightly alkaline wastes so little pH adjustment is necessary; they produce less floc and, therefore, less sludge; and they do not add dissolved solids (like sulfates and chlorides) to the effluent. This last advantage makes the prospects for reusing the effluent as makeup water more promising because of the absence of these corrosion promoting ions.

The primary disadvantage of using polyelectrolytes is cost. several times more expensive than inorganic treatment chemicals such as acid-alum. continuously renewed supply. ficult to mix, forming viscous, slimy solutions at concentrations below one half of one percent. or two weeks in many cases.

They may be

Many liquid polymers have short shelf lives and require a Dry polymers can be stockpiled but are dif-

Weaker solutions have storage lives of only one

Evaluating polyelectrolytes in the laboratory is more difficult than evaluating inorganics because of the tremendous number of compounds available and the endless combinations to be screened.

POLYMER-INORGANIC COMBINATIONS

Many polymers that work poorly or not at all by themselves can be very successful in combination with alum, ferric chloride, or one of the other inorganic flocculants. The inorganic is the primary flocculant, while the polymer serves to accelerate coagulation and agglomeration of small floc particles. Alum dosages can be reduced more than SO%, which helps offset the cost of the polymer.

TREAT OR HAUL AWAY

The decision to treat or haul away is directly dependent on the capital equipment needs, the amount and type of waste to be treated, and the regulations to be met. fied disposal company will remain the most practical means of "waste treatment." Studies have shown that at 1977 costs with waste below 200 gallons per day ( g p d ) , it is cheaper to have it hauled away. If the volume of waste is too small to justify treatment, only a storage tank is necessary. Otherwise, the absolute mini" requirements for batch chemi- cal treatment include:

For many small plants, waste hauling by a certi-

1. A tank of at least 500-gallon capacity. cylindrical with a depth to diameter ratio of about 1:l. Irregular shaped containers are impractical to use. A rapid mixer or variable speed mixer.

This should be

2. 3. A drain or siphon.

Experimentally, waste has been treated in 55-gallon drum, which might be feasible in a small machine shop but not for emptying a system of any significant capacity. liquid vacuum pump and the effluent drained. clarified effluent is siphoned off, and the sludge is removed.

If the floc rises, it can be skimmed by hand or If the floc sinks, the

Where cutting fluid central system or many individual machine wastes are to be treated on a regular basis, a more sophisticated batch treatment system is advisable:

1. A storage or waste equilization tank. the maximum waste coolant volume anticipated.

This must be larger than

2 . A batch or continuous reactor for the actual treatment process. The simplest of these is little more than a tank with a mixer, floc flotation and skimming equipment, and an effluent drain or pump as shown in Fig. D 2 - 1 . Most continuous chemical re- actors are proprietary units, specifically designed for a given application.

Dispersed or dissolved air flotation is usually employed to hasten floc separation and reduce chemical dosages. bubbles are needed, not just general aeration.

Very fine The minute

1. Activated Sludge

Fig. D2-1

bubbles attach themselves to the floc and enhance flotation. Oil may be separated by gravity flotation.

3. A floc, sludge, or oil handling system. In small plants, recycle of inorganic sludge is rarely justifiable, so the floc must be held separately until it can be hauled away. If much waste is available, sludge dewatering equipment might significantly reduce sludge volume and hauling costs. used for fuel, sold, or reprocessed by a reclaimer.

Free oil can almost always be

More complex waste treatment facilities indicate larger volumes of waste are being processed than spent cutting fluids alone. Large scale operations often separate the reactor tank or rapid mix tank from the flotation or clarification units. The cutting fluid waste may be fed directly into the general waste stream or pretreated before mixing as conditions require. sludge-recycle systems are currently in use.

Many complex

Biologica l Waste Treatment

Most organic compounds can be degraded by bacteria for waste treatment purposes. requirements:

Bacteria are divided into three types according to their oxygen

A m v b a urhich trequihe @e di64aLved axygen t a gtraw.

A n a m v b a w h i c h cannat f i v e i n an aehated envhonment. The ao-c&d acLLeAa/tive ba&e,tia which a d j a t ;ta eiRhm envhanme&. + michooqavLinm h ~ y u h e axygen ;ta gtrvw and m W p L y , bLLt n a t necenaa/tiey Q ~ e e oxygen.)

AEROBIC SYSTEMS

The activated sludge system is little more, in principle, than an aerated tank with good mixing equipment. basis and digested (degraded) by the bacteria.

Waste is fed on a continuous An activated sludge

unit has an effluent settling tank in which the biological floc may be settled or recycled to the influent stream. While bacteria are the dominant, active microbes in an activated sludge system, fungi and protozoa are also present in large numbers. Extensive, continuous or intermittent aeration of the fluid may be provided by dispersed air or by churning the water with hydraulic or mechanical devices. Biological floc forms spontaneously in the aeration tank, however some floc must be recycled to build up the sludge concentration needed to absorb incoming waste.

Consumption of the organic waste by the bacteria occurs after the waste is absorbed into the floc and continues after the floc has left the aeration unit. is characterized by overall removals of 85 to 95% of suspended solids, biochemical oxygen demand (BOD), and chemical oxygen demand (COD).

Clarified effluent, after sludge settling,

Retention times for activated sludge treatment range from a few hours to two days, depending on the method employed and the water.

2 . Trickling. Filters

Another aerobic treatment unit which deserves passing attention is the trickling filter. These are vertical biological reactors in which dissolved organic matter and fine suspended solids cascade down through a porous medium, often gravel, and contact the biological slimes coating the surfaces of the support medium.

Air is drawn by natural convection or forced through the filter bed under pressure to insure that aerobic conditions are maintained. Aerobic bacteria are more efficient than anaerobic bacteria in utilizing wastes and cause fewer problems with decay odors and gas production. Trickling filters pm b e are less effective in removal of BOD, COD, and suspended solids than are activated sludge plants because of less efficient fluid contact with the bacteria. filters are more resistant to shock loading and toxicity than acti- vated sludge processes, but require larger floor space and are more vulnerable to freezing if built outdoors.

Trickling

3 . Waste Stabilization Ponds

Stabilization ponds are large (many acres), shallow (no deeper than 4 feet) holding ponds where aerobic bacteria degrade the oily waste. Settling of suspended solids also occurs.

ANAEROBIC SYSTEMS

1. Lagoons

These ponds also require many acres and are usually feet deep. They are often used for pretreatment of

six to twelve toxic or

extremely polluted wastes. While such anaerobic systems are slower and less efficient than aerobic systems (longer retention times are necessary), they are less expensive to operate and require no attention. Noxious gases (by-products of decay) can be a problem, so these ponds are best suited for isolated areas.

2. SeDtic Tanks

Though rarely used in large industrial applications, septic tanks provide complete disposal of small-volume concentrated wastes which might otherwise be difficult to treat.

All of the above biological systems suffer from several drawbacks: they are limited in the amount of inorganic material they can remove; they do not allow for the recovery of any useful products, including oil, for re- cycle or fuel purposes; they must be protected from freezing and are inefficient at cold temperatures; they are sensitive to influent variations to a greater extent than most other treatments; and they may produce foul odors under a wide variety of conditions.

Nonetheless, their high BOD removal efficiencies and low maintenance characteristics have brought them widespread acclaim, particularly as methods of secondary treatment and effluent polishing. Confined for years to sanitary and food process waste handling, biological waste treatment will become increasingly important in cutting fluid and other industrial applications as effluent requirements become more and more stringent.

Physical Waste Treat men t

Physical methods are based on separation of water from the pollutants or complete destruction of the whole waste. space than chemical or biological treatment systems of equal capacity.

They generally require less

INCINERATION

Any process that uses combustion or chemical (catalytic) oxidation to convert liquid or solid industrial waste to gases and ash is termed incineration.

1. Direct Flame Incineration

Direct flame incineration is the most common type where the waste is sprayed into a methane, hydrogen, or liquid fuel flame. The water evaporates and organic materials oxidize to carbon dioxide, water, and other gases. waste stream, the incineration fuel cost may be substantially reduced. Air pollution is the most severe environmental limitation of flame incineration, but it can be controlled. major drawback.

If sufficient oil or other fuel is available in the

High operating costs are the

2. Catalytic Incineration

Catalytic incineration, more commonly called catalytic oxidation, is normally used to eliminate air pollution problems from chemical and industrial processes where organic contaminants are discharged to the atmosphere.

Catalytic incineration differs from direct flame incineration in that combustion occurs at lower temperatures. classic definition, enters into the reaction and is constantly changed throughout the reaction, the catalyst reverts back to its original state.

The catalyst, unlike the

However, upon completion of the reaction,

Application of catalytic incineration is wide and varied throughout the chemical and industrial field. The use of the catalytic incin- erator has become more popular in the sewage treatment and waste disposal field as well.

EVAPORATION-DISTILLATION

Among the most direct methods of waste treatment is evaporation. evaporation exceeds rainfall as in the West, this method is efficient and economical. In most industrial areas, evaporation must be accelerated by heating. the cost of evaporation of the total effluent stream is prohibitive.

Evaporation of water from concentrated sludges is more usual as volumes are considerably reduced. practical, again because it is not economically advantageous. recovery and in-plant requirements for distilled process water may pro- vide sufficient incentive to evaporate. from compact high energy devices to large shallow ponds for natural solar evaporation.

Where

Unless waste heat is readily available from some in-plant source,

Recovery of solids for recycle is rarely Oil

Space requirements vary greatly

F I LTRAT ION

Filtration is strictly a primary treatment procedure with widespread application to protect more sensitive treatments which follow. the same units used in cutting fluid maintenance are found in waste treatment. Vacuum filters and positive pressure filters, indexable media, fixed-bed filters, and disposable cartridges are all used, depending on the specific needs of the system and waste type. Filters are an indispensible part of many other treatment systems, but are not sufficient for cutting fluid treatment by themselves.

Many of

ULTRAFILTRATION

Ultrafiltration (UF) is a physical molecular separation process which operates at moderate pressure (30 pi). oil and suspended solids are separated from the oily wastewater. ultrafiltration is used to solve the difficult task of removing emulsified oils from wastewater, free and floating oils are more economically

Using a semipermeable membrane, While

removed by other processes such as skimming. Very small holes in the membrane, averaging 70 angstroms (2.75 x 10-7 inches) i n diameter allow permeate (c la r i f ied water) t o pass through the membrane while o i l and suspended solids are rejected. By recirculating the o i ly waste through the membrane, a large volume of o i ly waste is reduced t o a very small volume of o i ly concentrate, while the water (permeate) i s discharged t o the sewer. or used as auxiliary fue l .

Ul t ra f i l t ra t ion has several advantages over chemical treatment. chemical treatment methods work well on simple wastewater. metalworking wastewaters a re complex and do not readily respond to simple or advanced methods of chemical treatment.

The small volume of o i ly concentrate can then be reclaimed

Simple Unfortunately,

Since u l t r a f i l t r a t i o n i s a physical separation process, no special chemicals are required. Depending on the membrane used, wastes with temperatures as high as 120'F and pH from 1 .5 t o 13 can be processed direct ly without affecting performance. require chemical training.

Chemical methods must be adjusted as the nature of the waste changes. With u l t r a f i l t r a t i o n , o i l and sol ids are consistently removed regard- less of the var iab i l i ty of the waste. The treatment i s dependable.

Chemical treatment can create a large amount of sludge, which often requires further treatment. Ul t ra f i l t ra t ion yields a low volume of o i ly concentrate with less secondary disposal problems. also lower with u l t r a f i l t r a t ion . is controlling f lu id volume. Ul t ra f i l t ra t ion removes 90-95% of the water from an o i ly waste.

Operating personnel do not

Costs are The secret t o good waste management

Volume reductions 1 O : l are typical.

Although labor and transportation costs vary from one loca l i ty t o another, the cost relationship shown in the graph (Fig. D2-2) shows that u l t r a f i l t r a t i o n i s cheaper than chemical treatment a t l eas t with flows up t o 2000 gallons per day.

Treatment Cost TO Hauling Cost Ratio

1.25 !\ \

I- U L

!- v) 0

a

0 1000 1400 1 aoo 200 600

Chemical

Ultrafiltration

GAL. PER DAY FLOW

Fig. D2-2

The extreme of a "filtration" process is reverse osmosis in which a semi- permeable membrane replaces the filter media. waste is fed into the reverse osmosis (RO) unit at pressures of 400-800 pi, forcing the water and small dissolved molecules through the membrane and leaving the bulk of the organic and inorganic contaminants in a concentrated waste liquid.

The clarified, pretreated

Permeate from a reverse osmosis unit is usually high quality, reusable water, low in COD, color and inorganic salts, and devoid of suspended matter. beginning to make inroads into waste treatment facilities. cable as secondary or tertiary treatment, depending on the quality of pretreated feed water (UF is an excellent pretreatment) to it and effluent requirements necessary to attain for discharge.

Widely used in the plating industry, reverse osmosis is now It is appli-

Space required for RO is small. type of waste treated, and pilot testing is required to establish its reliability.

Operating costs vary widely with each

RO permeate quality exceeds municipal pretreatment standards and meets most direct stream discharge standards without further treatment.

CENTRIFUGATION

Centrifuges remove free or partially emulsified oil and solids only. They are not oily waste treatment equipment, but can be used for pre- treatment before emulsion breaking equipment. expensive and oil skimmers are more economical.

They are, however, very

ACTIVATED CARBON

Activated carbon, either as a slurry or as a filter, is used largely in tertiary or final wastewater treatment after the suspended solids and oils have been removed. render them ineffective.) surface of the fine carbon particles. other organics are removed in this way. has an active adsorbing surface measured in square miles.

(Oils coat the surface of the particles and Dissolved organic matter is adsorbed to the

Dyes, phenols, amines, and most A pound of activated carbon

Cost of carbon regeneration after use and release of inorganics such as sulfates from the carbon are the major drawbacks of this form of treat- ment, and its effectiveness depends on the degree of treatment preceding it.

W A S T E HAULING

Most industrialized communities have one or more facilities for pretreat- ing industrial wastes to minimum sewer requirements. (less than 200 gallons per day), infrequent, extremely complex or highly toxic wastes, the most economical form of Itwaste treatment" is having it

For small volume

D,2,9

hauled to such a facility. Costs per gallon vary with locale, type of waste, and the requirements the processor must meet (and these are in- creasing rapidly). Balanced against the cost of equipment and manpower required to operate even an unsophisticated waste treatment unit, however, the cost of hauling waste away is often less than treating it. fluid wastes, the break-even point is around 4000 gallons a month with waste hauling costs ranging from 4 t o 15 cents per gallon.

For cutting

RECYCLE-RECOVERY

The long-term goal of laws governing water pollution is "zero discharge." In proposed standards, the metalworking industry is expected to meet this goal in 1983 by using the best available technology (BAT).

This deadline, although it may be extended, compels the metalworking industry to find ways of reclaiming o r recycling waste materials used in metalworking processes. material removal" process, and the technology for reclamation and recycling is available. could be called ;the l d e d Paace& SqnXem, Xhe l d e d Recuvc%q SqbXem, ;the TdeaL Re.cRamdon Sybltem, m d Xhe l d e d Recyde Sy&&m.

Cutting fluids fall under the "mechanical

Possible methods that may be used include what

Those who utilize this technology, however, find that a good cutting fluid management program is a necessary prerequisite for success. fluid management program includes the following steps:

A good cutting

1. 2. 3.

4. Use low mineral content water. 5 .

6. Control tramp oil emulsification. 7 . Aerate the mix. 8. 9. Use additives when needed.

Assign responsibility of control to one person. Start with a thorough chemical cleanout. Select a premium performance product.

Tie all machines to a central system with a positive filter.

Flush all chips to the filter.

10. Employ good housekeeping.

Ideal Process Svstem

A good cutting fluid management program alone prolongs the life of a cut- ting fluid. illustrated in Fig. D 2 - 3 , the life of a cutting fluid may be extended to five or possibly ten years.

Since water comprises from 90-98% of a water-based cutting fluid mix, its quality is foremost to cutting fluid performance. than 200 ppm hardness) can cause deterioration of a lubricant system D,2,10

When it is incorporated into an ideal process system as

Hard water (greater

I

Fig. D2-3. IDEAL PROCESS SYSTEM

L

and form scum in chemical emulsion and emulsifiable chemical cutting fluids.

Dissolved solids are also important. Minerals such as chloride and sulfate promote corrosion and rancidity problems. a high mineral content can cause deposits on machines. continue to build up in the mix with evaporation and addition of fresh cutting fluid mix. high quality water.

Water softening only exchanges calcium and magnesium ions for sodium ions, preventing the formation of hard water scum. content, however, will tend to increase. The best treatment for providing the high quality water needed in the ideal process system is deionization or demineralization, which remves all minerals.

Oil removal equipment may be sophisticated or simple, depending on the amount and type of oil that contaminates the system.

The Henry Bact-Oil Separator (BOS), a thermal treatment unit. removes oil and kills bacteria. Centrifuges remove free floating oil and loosely emulsified oil. Belt and rope skimmers may be adequate if seals and lubricating systems are well maintained so that oil leakage is minimal and the oil is not completely emulsified.

The ideal process system incorporates a positive filtration unit. This is necessary to remve both large and small fines. generally is less expensive and causes fewer problems than the pressure type.

Salts from water with Dissolved solids

Water treatment, therefore, is required to obtain

The total dissolved solids

1.

2 . 3.

A vacuum type filter

L

D,2,11

Ideal Recovery System

For those who have individual machines instead of central systems, the same principles may be applied as shown in Fig. D2-4.

PLANT WATER

NEW FLUID USED FLUID TO MACHINE FROM MACHINE

CYCLONE

DUAL COMPARTMtNT CRU

OIL REMOVAL DEVICE

CLEAN FLUID RESERVOIR BAFFLED SETTLING TANK

Fig. D2-4. IDEAL RECOVERY SYSTEM

The cutting fluid is premixed with deionized water by a proportioner and fed into a dual-compartment CIMCOOL Recovery Unit (CRU) which transports the mix to the individual machines. the filter basket into a holding compartment, the CRU installs the fresh mix and then carries the dirty fluid back to a centrally located holding tank. to remove swarf. tank-cyclone filter is less expensive. Again, provision is made for o i l removal.

After pumping the used fluid through

Here, a settling tank is used in combination with a cyclone filter A pressure filter would be even better, but the settling

After the fluid is cleaned, it can be held in a clean fluid reservoir and aerated to prevent its becoming stagnant. clean side of the CRU and returned to the machines as needed. for maxim life, fresh cutting fluid mix should be used to charge the machine tool reservoirs; the cleaned fluid is then used for makeup.

Then this can be fed into the Note that

Ideal Reclamation System

Like everything else, the cutting fluid eventually wears out, even when using the ideal process system. is an extension of the ideal process system wherein another holding tank is added which allows more time for treatment. used on both process and reclamation systems through piping. removing swarf and oil, the cutting fluid mix is checked for bacteria, bactericide, corrosion inhibitors, pH, and by other tests that indicate its condition. Adjustments are made as indicated by the tests, and the fluid can then be used as makeup.

The ideal reclamation system (Fig. D2-5)

The same equipment may be After

D,2,12

CHECK AND ADJUST AI CONCENTRATION 81 OH CI BACTERIA DI CORROSION INHIBITORS

OIL REMOVING DEVlC A1 O I L SKIMMER 81 CENTRIFUGE I 81 CENTRIFUGE

EXTRANEOUS OIL

POSITIVE FILTER

E

RANEOUSOIL

I ~ O ~ G k K N K I I I X GALLON CUTTING FLUID TANK I SOLIDS

I I REMOVED

RETURN LINES

Fig. D2-5. IDEAL RECLAMATION SYSTEM

Ideal Recycle System

The best approach to zero discharge is the ideal recycle system (Fig. D2-6) .

DEIONIZED WATER OIL REMOVING DEVICES A i SKIMMERS B i CENTRIFUGE

EXTRANEOUS O I L

X GALLON X CiALLON EMULSION BREAKINL CUTTING FLUID TANK HOLDING TANK EOUIPMENT

A I UF 131 UF ~ RO Ci CHEMICAL

SOLIDS REMOVED

COAGULATION

X GALLON TREATED WATER

FOR MAKEUP

Fig. D2-6. IDEAL RECYCLE SYSTEM

SLUDGE DISPOSAL

Starting with the process system, the cutting fluid goes into a holding tank for removal of extraneous oil. equipment which separates the oil and some cutting fluid ingredients and contaminants from the water. technologies--chemical waste treatment or ultrafiltration.

Then it is piped to emulsion-breaking

This can be done by using one of the two

D , 2 , 1 3

With chemical treatment, additional treatment may be necessary to remove particular materials before the effluent is acceptable for reuse as make- up water in the cutting fluid system. Ultrafiltration leaves some of the cutting fluid constituents in the water, which may be suitable, without additional treatment, for makeup water in the same cutting fluid.

When water is intended for unrestricted reuse throughout the plant, a reverse osmosis (RO) unit must be attached to the UF unit. gross contamination and the RO further cleans the water by removing salts and minerals.

The UF removes

D,2 ,14

Chapter 3

WASTE TREATMENT T E S T S FOR D I S P O S A L O F C U T T I N G F L U I D S

After waste treatment is complete, a sample of the effluent must be checked by a number of tests to be sure it meets the applicable water quality standards. with an indication of their usefulness in regard to cutting fluid wastes, are outlined below.

Short descriptions of most commonly required tests,

B i o c h e m i c a l O x y g e n D e m a n d [BOD]

The BOD is a measure of the amount of oxygen used by microorganisms during the process of decomposing organic waste. The oxygen is needed to sustain life in natural waters and most wastes use up the oxygen in the water faster than it can be replaced. In pollution control work, the BOD usually is measured at 2 0 ° C over a five-day period. Saturated water at 20°C contains only 9 . 2 milligrams/liter ( m g / R ) dissolved oxygen, while the BOD in many wastes may be over 1000 m g / R .

The BOD test is subject to a great many variations and has not been found to be very reliable.

C h e m i c a l O x y g e n Demand {COD]

The COD is a measure of the amount of oxygen used by a chemical process in the consumption or total oxidation of matter in water. usually twice the measured BOD (5-day) or greater.

The COD is

While certain chemicals are not measured by one test that are measured by the other, the discrepancies between BOD and COD testing are small enough so that an estimate of BOD may be obtained from the COD in many instances.

The COD test requires about three hours and is much more precise than the BOD test. can be maintained.

There are no interferences if consistent sampling techniques

O i l Grease , Freon E x t r a c t i o n , etc.

The terms "oil and grease" are defined by the test method used and are not just petroleum products. in a separatory funnel, also measures animal and vegetable oils and fats and many polar organic compounds. biodegradable compared to most organic compounds encountered in waste cutting fluids and most municipal sewers limit their discharge to 100 parts per million ( p p ) o r 0.01%. procedure to exclude non-mineral oils are available, but the burden of proof falls on the users when discharges above the oil limit are requested.

The preferred test method, the Freon extraction

Petroleum oils and greases are non-

Modifications of the Freon extraction

Suspended Solids Suspended solids are those solid materials in a liquid waste that can be filtered out by a 1.0 micron filter. are 300-350 p p suspended solids. solids can be readily settled in most waste effluents. results can be dried or treated separately from the rest of the waste stream.

The usual sewer discharge limits Both organic and inorganic suspended

The sludge that

The significance of suspended solids in pollution is that they are a visible sign of contamination. of clean water.

Their absence, however, is not indicative

Total Solids

When all of the water is evaporated from a sample and the remains are dried at 103OC, the total solids content may be measured. Aside from the suspended solids, which are a part of the whole, all the inorganic and non-volatile organic materials dissolved in the waste effluent constitute an additional load on the receiving sewer or stream. are sometimes increased but usually are unaffected by standard waste treatment procedures.

Dissolved inorganics

While rarely used as a standard waste treatment parameter, total solids provide significant amounts of information about overall water quality and the possibilities of water recycle.

Acid Anions The dissolved inorganic materials referred to above include salts of many metals. phosphate appearing in lesser amounts. Chemically these anions are acidic and contribute to the corrosive properties of water, making their minimi- zation in cutting fluid makeup water very important. The only acid anion prohibited to any extent in most discharge water is cyanide because of its toxicity. Continuous use of aluminum sulfate in waste and drinking water treatment and a widespread use of salts in general has measurably increased both sulfate and chloride levels in surface and ground water in many sections of the country. there are few regulations limiting either.

Phosphates are common in wash water solutions as cleaning agents. are basic nutrients for bacteria and algae and are limited very strictly in direct discharge to open waters. cutting fluid wastes as contaminants from cleaners.

The predominant wastewater salt is sulfate, with chloride and

Yet, since actual health hazards are negligible,

They

Phosphates are occasionally found in

Heavy Metals

A wide variety of heavy metals are known to be toxic to plants, bacteria, fish, animals, and man--even in small quantities. Testing procedures are well established and regular metals testing programs must be kept on all waste effluents. Certain product changes have been made in CIMCOOL cutting

fluids to eliminate heavy metals from the product concentrates and new raw materials are analyzed with this in mind. approximate limits encountered for metals in cutting fluid wastes. These limits vary greatly from one community to the next.

The table below gives

Name (symbol)

Cadmium (Cd) Chromium (Cr) Hexavalent chromium (Cr'6) Copper (CUI

Mercury (Hg) Iron (Fe)

Lead (Pb) Zinc (Zn)

Sewer Limits ( p y ) Stream Limits ( p p )

1 .O-5 .O 1.0-25.0 0.5-10.0 1.0-3.0 5.0-no limit none detectable 0.5-1.0 1.0-15.0

0.02-0.1 0.5-1.0 0-0.05 0.1-0.5 0.5-5.0 0.0005 or none detectable 0.1 0.6

Of the above list, copper, iron and zinc pose some problems in pretreated cutting fluid wastes. most metals will precipitate as hydroxides near neutral pH.

Solubility of all metals increases at low pH and

Phenols Phenols are limited for several reasons: ment bacteria except in small amounts; they are not removed by standard waste treatment procedures; when chlorinated, they impart strong taste and odor to water even in minute concentrations (fractional parts per billion); and some chlorophenols are suspected carcinogens.

Clarified wastes may be treated with activated charcoal or carbon to remove phenols and oxidation or incineration may also be used.

they are toxic to sewage treat-

Surfactant s

Like phosphates, surfactants are nutrients for bacteria and algae, con- tributing directly to eutrophication of rivers and lakes. limited in sewer discharged effluents, wastes sent to open waters must be tested for surfactants.

Though rarely

The MBAS (methylene blue-active substances) test is suitable for use on pretreated, clarified waters. nonionic and anionic surfactants, many of which are removed in the clarification process.

Cutting fluids contain large amounts of

The range of acceptable pH varies little from one sewer system to the next with a low of 5.5 o r 6.0 to a high of 8.5 to 9.0. largely t o avoid corrosion of the sewer lines, but are also beneficial in promoting precipitation of metal hydroxides and biological activity.

These limits are set

D,3 ,3

Chapter 4

CIMCOOL TECHNICAL SERVICE

I N WASTE TREATMENT

The Cimcool Division of Cincinnati Milacron Company offers the following waste disposal capabilities and services. Requests for assistance and x lephone (513) 841-8133. They work should be directed through the P. 0. Box 9013, Cincinnati, OH 452

Our capabilities are :

1 Technical Services Department,

will route complex and detailed problems to the

1.

2 .

3.

4.

5.

6. 7 . 8.

Evaluate the effects of CIMCOOL products on a customer's existing waste treatment process. Suggest modifications to existing treatment methods or equipment to improve results. Develop chemical break procedures on actual cutting fluid wastes. To determine the effectiveness of the procedures, we run COD, dissolved solids, suspended solids, oil and grease, and metal analyses. Evaluate chemical-polymer break procedures if the customer is interested. Discuss other disposal methods such as incineration, electrolysis, ultrafiltration, reverse osmosis, and bacteriological. Provide current wastewater quality test procedures. Discuss current and future EPA requirements. Discuss requirements for water recycling programs.

Developing wastewater procedures is a tricky business and although we have learned a lot in recent years, we do not have all of the answers. After taking a look at the customer's needs and problems, we may advise that a consultant or a firm specializing in the field should be contacted.

Procedures developed on fresh CIMCOOL mixes have limited value. A repre- sentative sample of the customer's waste must be used. sample of waste is needed. immediately by air freight or U. S. Postal Service, Special Delivery, to:

A two-gallon This sample (fresh) must be taken or sent

ron/Products Division Laboratory Services

ALL PACKAGES SENT TO THE MARBURG AVENUE ADDRESS OR VIA UNITED PARCEL SERVICE (UPS) WILL BE DELAYED AND MAY SPOIL IN TRANSIT, MAKING TREATMETTI' STUDIES IMPOSSIBLE.

In order that we may better serve the needs of our customers, we have adopted a waste treatment information sheet (at the end of this chapter).

D,4,1

It mst be filled out and sent in with the waste sample and a carbon copy to the Cimcool Technical Services Department before any work can begin.

New plant construction, new machines, and new processes greatly affect cutting fluid maintenance and waste treatment. Many customers solicit help when such alterations or additions are planned and we welcome participation in such changes. significant difference in ease of operations and these changes are best made before construction.

Often minor modifications can make a

CIMCOOL Waste Treatment Information Sheet

A. Company Waste Disposal Engineer

Location Telephone

B. Product

1. CIMCOOL cutting fluid and approximate concentration?

2. Quantity of waste to be dumped?

3. What other products and in what ratio are they combined with the oily waste?

4. When will the disposal occur?

C. Treatment Facility

1. Accurately describe the waste treatment facility. Include tank and storage volume, or dimensions and flow diagrams, and availability of heat and materials of tank construction (for p H limitations).

2. Chemicals currently used in waste treatment? Yes No

a) Sulfuric Acid b) Aluminum Sulfate c) Polymers: 1)

? \ L I

3 ) d) Other:

What are the chemicals they cannot or will not use?

3. Describe normal waste treatment procedure, including pounds of chemicals per 1030 gallons of waste treated, minimum p H attained, holding times, heat, etc.

Page 2 Waste Treatment Information Sheet

4 . Is sludge or oil separated from the waste water or disposed of with the effluent? Yes no If separated, what do they do with sludge or oil?

D. Effluent Limitations

1. Where is the waste effluent discharged? stream sewer other

2. What are the specific effluent limitations in ppm imposed on this discharge? NPDES permit or sewer regulations? a) BOD f) Iron b) COD g) Ammonia Nitrogen c) Suspended Solids h) Phosphate d) O i l and Grease i) e) Chromium j )

If possible, include copy of local requirements.

E. Other Considerations

1. Are other types of waste treatment processes being used or considered? Yes no If so , what are they?

2. What are the time limitations for treating this waste?

a) How long will the system be shut down for cleaning?

b) Are other wastes processed in the same unit?

no 3 . Is contract waste hauling a possibility? Yes If s o , what is the cost per gallon?

If chemical break procedures are to be developed by the laboratory, a minimum of two (2) gallons of effluent - either waste cutting fluid or waste mix as it will be treated - is required.

submitted by date

Send Information Sheet to: Cincin ilacron/Products Division