I

I i

Using sorbents for waste -

minimization One way to avoid waste disposal problems is to minimize waste

production at the source. Recycling coupled with reclamation using new synthetic sorbents is preferable to landfill disposal.

By Lael Pickett, Regulatory Affairs Specialist, 3M Oc- cupational Health and Environmental Safety Div.

lant and facili- ties engineers P face a de-

manding paradox. As they implement procedures to safely control, capture, and dispose of spilled chemicals, process fluids and other hazardous liq- uid materials, the problem of how to dispose of cleanup materials surfaces. While maintenance sorbents are cost-effec-

mental Protection Agency (EPA) has empha- sized the importance of effectively treating hazardous waste before disposal in a landfill. The 1984 Hazardous and Solid Waste Amendments (HSWA) to the Resource Con- servation and Recovery Act (RCRA) of 1976 apply to companies that generate large and

Industrial maintenance sorbents contain, control, and absorb non-aggressive fluids typically found in manufacturing and maintenance operations.

small quantities' of hazardous waste. These include chemicai and paper manufacturers, petroleum refineries, transportation equip- ment and machinery manufacturers, vehicle maintenance firms, metal manufacturers and finishers, and printing companies.

Treatment alone, however, will not remedy all hazardous waste problems. The EPA now en-

74 0 Engineer's Digest 0 October 1993

information

D T O - rtionP pace utilization.

!@wages waste minimization through the re- recycling, and reuse of hazardous

such as organic and dhlorinated sol- vents, alcohols, water- and oil-based cutting fluids, petroleum products, paint thinners, and ‘machine coolants. Any program for reduction

recycling of waste materials is inevitably site- and plant-specific. Nonetheless, waste dmization techniques fi$l within’ four ma- 'jar categories:

Inventory manage-

waste generated, significantly reducing trans- portation and disposal costs. Also, they can replace virgin fuels in waste-to-fuel opera- tions.

The American Society for Testing and Methods (ASTM) has developed standardized sorbent test methods to evaluate charac- teristics of sorbents and the fluids to be sorbed.

Performance characteristics of sorbent

e, or exchanging tes-are complex expensive. A com-

overlooked and

eneral term used to

n manufacturing or emical liquids. Their

absorbency mini-

I materials are ranked by their sorbency rate I

Electric Metering Corporation U.S.A. ’ .

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. .

. -

(time required to become saturated), volume (amount of liquid a sorbent can hold), and ratio (how much liquid by weight can be absorbed in relation to the weight of the sorbent).

Fluid characteristics that affect sorbent performance include density (the mass of a substance per unit volume), viscosity (resis- tance to flow), and surface tension (intermo- lecular forces of a liquid acting at the surface to hold it together).

Until just a few years ago, the most preva- lent types of sorbents available to plant and facilities engineers were natural organics (corn cobs, wood pulp, cotton) and inorganics (clay granules, silicates). While the advantages of these conventional industrial sorbents include low cost and light weight, disadvantages in- clude low sorption rates, disintegration in the presence of harsh chemicals, and inconven- ience. Using them is labor intensive, and they

~

Circle 605 for more information

are bulky.

New sorbent technologies

Recently, a new cate- gory of synthetic sorbent materials became avail- able. Manufactured from polyolefins (poly- ethylene * or polypropylene), these sorbents are inert and lightweight. They have high sorbency capacity and are available in a va- riety of configurations, including pads, rolls, booms, and pillows.

se new synthetic sor- s fall into two cate-

gories depending upon whether they attract (philic) or repel (phobic)

er- or oil-based flu. ir, philic jori.pho, perties dictate

their appropriate us cleanup*application! , There are other dis- tinctions among sor-

t bents based on their per- formance charac-

contain media that will

', a new cate-

nto two cate-

not absorb particular liquids or ones not chemically compatible with them. For exam- ple, untreated polyolefins usually will not ab- sorb aqueous liquids.

Oil sorbents, for example, are selective sor- bents because they selectively remove floating oil from water, although they provide oil re- covery on land as well. Typical applications include the spill control of lubricating oil, mo- tor oil, geptubes, hydraulic oil, and other petroleum products in plant production and maintenance operations.

Chemical or non-se- lective sorbents are in- ert and can be used for almost all liquids. In- dustrial maintenance sorbents, sometimes called universal sor- bents, are of this kind. They contain, control, and absorb non-aggres- sive fluids typically found in manufacturing and maintenance op- erations: Most hazard- ous and non-hazardous liquids including petro- leum- and water-based fluids, acids; and b

Specialty sorbents al- ter the state of the liquid

thiugir the use of spe-

regulations require that a waste solvent or paint be contained and solidified before disposal. .

Reducing waste disposal costs Current EPA regulatory standards and eco-

nomic considerations have fostered a recom- mended strategy for waste minimization, This new strategy includes waste minimization as a first important step in an overall approach to waste management. The following hierarchy

Modular Storage Systems

,

I

summarizes the new national policy for waste management:

First, consider source reduction-activities that reduce or eliminate the hazardous waste generated by processes.

Second, consider recycling-the use, reuse, or reclamation of a waste, either on site or off site, after it is generated by a particular proc- ess.

energy. Some wastes can be beneficially used as fuel under carefully controlled conditions.

Fourth, consider treatment to reduce the toxicity of hazardous waste.

Finally, and only as a last resort, consider land disposal.

As the price of storage space, labor, haul- ing, and other hidden disposal costs continue to rise, the advantages of new sorbent methods

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Containing and dis- posing of 10 gallons of spilled fuel oil provides an example of evaluat- ing these costs. Due to varying sorbency rates, v.olumes, and ratios, ground corn cobs will produce 90 pounds of waste, clay granules will produce 168 pounds of waste, and a poly- propylene synthetic sor- bent will produce 76 pounds of waste. Al- though synthetic sor- bents initially are more expensive than these or- ganic sorbents, their net cost is, for example, about 30% of clay gran- ules, after factoring in the costs of a disposal container, labor, and a

!

Waste minimization -

A separate but related consideration is short- and long-term sorbent stability . 'Commonly used sorbent materials are effective in captur-

Circle 608 for more information ' 84 Engineer's Digest 0 October 1993

-I

of waste. Al-

Fee” for landfill

rate but related ation is short-

bent materials

ing and retaining waste liquids. However, Over time, if dumped in a landfill, virtually all of them will leach sorbed fluid.

The EPA now requires mechanical processing (using a centrifuge or wringer to remove “free liquids”) of all sorbent materials that retain hazardous liquids, be- fore those sorbents go to a landfill. For conventional, natural sorbents, this process can be time consuming and ineffective. However, companies can actually benefit by reclaiming sorbed liq- uids-cutting and lubri- catingoils, solvents,and process fluids, for exam- ple-from synthetic sor- bents and reusing the liq- uids. This strategy can reduce disposal costs by up to 50 %.

An alternate method involving synthetic sor- bents is “waste-to-fuel” operations that “recover” the fuel value of hydro- gen- and carbon-based hazardous materials as they burn, thereby reduc- ing a company’s need to purchase fuel.

New attitudes about hazardous materials -

Many plant managers and engineers see a link between increasing waste management costs for industrjr aild rising environmental concerns of society. The resulting socio-economic pres- sures cause companies to be more efficient in

the management of waste, including toxic and hazardous substances.

Waste reduction requires a new approach to hazardous-materials management. Tradi- tional thinking places all the responsibility on a few environmental experts in charge of treatment. The new focus makes waste re- duction a collective responsibility. The new focus also produces a new role for manag- ers a‘nd engineers, who are uniquely quali-

Circle 609 for more information October 1993 0 Engineer’s Digest 0 85

fied to solve industrial waste reduction prob- lems. Why? Because they have the required background in disciplines critical to design and operation of industrial manufacturing and production processes.

Experience with successful waste reduc- tion programs clearly indicates how atti- tudes are changing. For example, the old attitude that environmental compliance is too expensive must give way to a new atti-

tude that waste reduction can be a sound in- vestment to control and reduce operational costs. ia

Lael Pickett is regulatory aflairs special- ist for 3M’s Occupational Health and Envi- ronmental Safety Div. A .graduate of the University of Wisconsin with B.S. degrees in

. chemistry and business, Pickett has worked for 3M for 15 years, specializing in hazard-

Overhead Work: simple, safe and cost eff&e!

The Tele-Tower@ Adjustable M o l d can be set up by one man in five minutes and tele- scopes to deliver plat- form heights from 2’ to 11’. -

Integral outriggers, provide a base width ad- justable from 31’’ to 6‘.

For medium height overhead work the Tele- Tower@ is d e r and more productive than

ladders and more cost dective &an common stacking scatrOds and hydraulic l i i .

For more information contact:

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Circle 615 for more information 88 Engineer’s Digest October 1993

ous materials and waste regulation. A member of the Chemical Manufacturers Associa- tion, she sits on the boards of directors of the Hazardous Materi- als Advisory Council (HMAC) and the Coun- cil on Safe Transporta- tion of Articles. Pickett chairs the HMAC In- ternational Regula- tions Committee and participates regularly in the work of the United Nations ’ Com- mittee of Experts on dangerous goods.

r answers to your questions on the use of sorbents for waste mini- mization and related topics, you may contact Pickettat OH&ESD, 3M Center, Bldg. 260-3B- IO, St. Paul, MN 55144- iooo.

For general informa- tion on maintenance sorbent materials, circle 446.

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The PS Series of submersible Linear Motion Transducers provides accurate position measurement in a wide range of hostile atmospheric and fluidic environments. MagneTek. Cir- cle 100.

Heavy-duty, industrial wiping product made of cellulose fibers for quick, complete absorption of wa- ter, grime, oil, and chemical spills. The non-woven fabric contains no adhesives or chemical binders. Kimberly-Clark. CirclelOl.

Circuit Guard portable GFCIs provide ground fault protection for indoorloutdoor applications by interrupting electrical power forequipment loads when ground leakage reaches 4-6 milliam- peres. Hubbell Inc. Circle 102.