C O N T E N T S

Introduction to Profiles in Prevention

Learning from Emissions Reductions

Catching Waste and Cutting Costs

Recycling Calcium

Room for Improvement

From Deepwells to Marketplace

Acid to Acid, Waste to Waste

Separating Wheat From Chaff

"Clean" Cleaning

"Whiter Than White" Without the Waste

Efficiency Pays

Less is Better

Restricting Pollution Expanding Capacity

Chemical Cousins

Waste Acid Gets Second Life

Savings in Tandem

Plugging Leaks

P R O F I L E S I N P R E V E N T I O N

Pollution prevention is our national goal, a hallmark of the chemical industry and die subject of these success storics - tales of innovation and change. The United Statcs Congress passed the Pollutioii Preyention Act of 1990, and the chemical industry reported that in 1993 it recycled, recovered for energy or treated 93 percent of its byproducts*.

From 1987 to 1993, member companies of thc Chemical Manufacturers Association -which represent 90 percent of the US. productive capacity for basic chemicals - reduced 6y halj'releases to the environment'. This booklet tells how.

The profiles are in depth. They give chapter and verse. They name names of chemicals, of plants and laboratories, and of scientists and operators - the people who, working together, solved the problem, prevented pollution and helped the environment. Some cases required extensive investment and others, imagination and elbow grease. Some cases are rocket science, at Lhc cutting edge of technology and others represent ingenuity, tinkering at its best.

The U.S. chemical industrv is a worM leader and has a legacy of innovation and change in the marketplace. Witness thc cornucopia of new products that come from its laboratories and plants . The industry employs 90,000 scientists and engineers and underwrites 13 percent of US. industrial research and development.

3 ~ 1 r c c : Envil-oiiincnral Pmteruon Ageiim, Toxirs Rrlrar 111\~~111orv.

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The following pages tell of the industry applying its strengths in science and technology to the environment. The case studies clearly demon- strate that the chemical industry has the skill, the

problems - set priorities, choose solutions based on t h ~ best available scientific understanding, use a casebycase approach, respond to public con- cerns apd look for cost-effective solutions.

competence and the tools to improve environ- mental quality.

Voices are now being heard that characterize envi- ronmental protection as a post-World War I1 suc-

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cess story. They say: not that there isn’t more to be done, not that there hasn’t been muddle and inefficiency in some areas, but our progress has . pollution. \

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yield improvement - making more product with The idea goes back 100 years when it was called

the same amount of raw material. In 1988, the

been great and we’re building on strength. The chemical industry would agree, and cite the

in Prevention as cases in point.

Chemical Manufacturers Association adopted Responsible Care@, an industrywide initiative to better safety and environmental performance and to address pu6lic concern about chemicals.

Responsible Care@ requires CMA member compa- nies to put in place six Codes of Management Practice, over 100 in all, including pollution pre- vention. Companies use a hierarchy of pollution prevention techniques, among them, source reduction, recycling, recovery for energy and treatment. CMA believes such an approach is the productive way to solve environmental

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E M I S S I O N S R E D U C T I O N S

Chevron produces the pesticide Orthene at its Richmond, California plant. Methylene chloride, plays a key role in this process as a carrier solvent and reactant. The reaction equipment is housed in a building which is under negative pressure and has a scrubber to prevent emissions. However, some thirty pounds an hour of methylene chloride emissions were emitted to the atmosphere.

Though the plant was permitted to emit 100 pounds/hour of methylene chlc- ride, Chevron set out in 198’7 to drastically reduce these emissions through a comprehensive source reduction program. Source reduction efforts had begun at the plant in the early 1980s but were not well focused. The ambitious goal of reducing methylene emissions by 90 percent provided the needed impetus for Chevron’s source reduction efforts.

Management had two options. The first was to install a carbon treatment unit that would require a capital investment of $10 million. In addition, the treat- ment process would have significant operating costs and would generate large volumes of hazardous waste for disposal. The other option was to focus on smaller, less capital-intensive changes that could add up to real reductions in methylene chloride emissions. Chevron chose the latter course to reduce waste at the source.

Participation among all levels of plant personnel was key to the effort. Operators, mechanics, technicians, operating supervisors and plant engineers formed teams to brainstorm ideas for emissions reductions. The quick fixes were tackled first to maintain enthusiasm and create an environment of suc- cess. Priority was given to the projects that the operators, mechanics and tech- nicians felt were most important.

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A GasTech analyzer was used to measure emis- sions sources and help prioritize reduction steps. By 1990, the plant had reduced methylene chlc- ride emissions by 80 percent, mostly through these basic, cost-effective initiatives:

increasing preventive maintenance efforts;

implementing more frequent shut downs to repair methylene chloride leaks;

purchasing improved area monitoring equip- ment to detect problems more accurately; and

improving gasket materials, pump seals, valve packings, sampling equipment and procedures.

The total cost of these changes was $200,000. By 1990, the savings from recovering the methylene chloride offset the cost of emissions reductions.

Reducing methylene chloride emissions the last 10 percentage points proved the most challeng- ing. The plant installed an on-line methylene chloride analyzer at a cost of $140,000 to help plant personnel spot any fluctuations in emissions and correct the problem immediately.

It worked. The source reduction efforts were so successful that Chevron was able to use data from the on-line analyzer to negotiate a plant

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production increase worth millions of dollars to the facility. The terms of the permit required that the methylene chloride emissions cap be reduced from an average of 100 pounds/hour to three pounds/hour, and plant management was confi- dent enough in the reductions ah-eady made to accept the permit conditions.

Chevron also learned some valuable lessons from the process:

Management must be sold on the program. It is critical that management ippreciate and

tion prevention requires the time and atte

ments within a plant.

Management’s commitment to be demonstrated with reso

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of time. And be prepared to spend the most money to get the last 10 percent.

Get some quick successes. Don’t get caught in analysis paralysis. Do the easy, inexpensive projects first. This gets and keeps the momentum going.

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Avoid impatience.

frequent to capture progress in the proper perspective.

There needs to be something in it for everyone. That “something” can be job security, improved worker safety, approval, recognition, a job made easier, or contribution to a good cause.

Measure/feedback is important! Used properly, measurement can really moti- vate. At Richmond, it also became an impor- tant operating instrument for plant personnel.

A N D C U T T I N G C O S T S

Occidental Chemical (OxyChem) uses nine heat exchangers to cool and remove impurities and particulates from the petrochemical gas stream at its Chocolate Bayou Plant in Houston, Texas. The plant makes ethylene and propylene from oil and natural gas.

Each month, two of the heat exchangers are removed for cleaning, generating a two-phase waste stream. Formerly, this waste was solidified with an absorbent prior to disposal. The resulting waste had a benzene content of 20 to 30 ppm a d was classified as hazardous.

Plant personnel targeted this waste stream for reduction beginning in 1987. Ron Wages, environmental technician, organized a team that included Paul Davenport, waste disposal coordinator; Hymie Guel, waste disposal technician; Joe Moreno, maintenance engineer; and Harry Gaul, operating technician, Olefins Unit.

The team determined that this hazardous waste would be substantially reduced by disposing of the liquids and solids individually, thus eliminating the use of an absorbent. Separation could be accomplished simply, by using catch-baskets with screens to filter the solids and collect the liquids.

The team initially considered installing a permanent, stationary catch-basket on each heat exchanger but instead opted to design an innovative, portable catch-basket. The basket can easily be moved to any of the nine exchangers that are being cleaned. The total cost to implement the project was $3,500.

OxyChem’s simple filtration system has had both environmenkil and econ- omic benefits. Hazardous waste was reduced by 65 percent, or 108,000 pounds

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a year. The company has saved $125,000 annually in disposal and labor costs - adding absorbent to solid9 the liquids was a labor- intensive process.

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This is the kind of project that enabled the Chocolate Bayou Plant to reduce hazardous waste generation by 58 percent from 1987 to 1993. The plant is a member of the Clean Texas 2000 Industry Honor Roll, which requires members to commit to reducing hazardous waste by 50 percent from the 1987 levels by the year 2000.

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Mike King, superintendent of environmental operations; and Jerry McDonald, supervisor of wastewater Geatment. The internal team was assisted by John Roy, county agent for the Louisiana Cooperative Extension Service.

Economic and environmental feasibility studies were used to examine the process. Four options were considered

Continue landfilling. This would increase the burden on the state’s industrial landfills and was the least desired alternative;

Replace lime as the neutralizing agent with sodium hydroxide. This alternative was cost prohibitive; and

Recycle the calcium carbonate. Punfylng the calcium carbonate would allow it to be used as a lime substitute for farming, eliminating it from the waste stream entirely.

The team focused on modifying the filtration process to improve the quality of the calcium carbonate, since re-use was the most attractive option. A filtration press was added to the process

ening and punfylng them for re-use. B&ed on extensive in-plant and in-field studies, Ciba-Geigy obtained a temporary beneficial re-use permit in 1988 from the LDEQ‘s Solid Waste and Water

The St. Gabriel plant’s waste minimization project represents a win-win situation for all involved - Ciba-Geigy, local farmers and the environmental community:

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Quality divisions to use the material as a pH modifier for agricultural soils.

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The company secured the cooperation of the Louisiana Cooperative Extension Service to distribute the recycled calcium to local farmers. From 1989 to 1990,2,900 tons of calcium car- bonate were donated to 15 farmers for use as an agricultural soils pH modifier, saving them approximately $75,000 in lime costs and signifi- cantly improving crop yields. Based on the success of the program, the LDEQ approved the final 5-year permit in March 1991 - the state’s first beneficial re-use permit.

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a - Ciba-Geigy saved over $595,000 per year in dis- posal costs, with an investment of $1 15,000 per year for program implementation.

Approximately 14,882 tons of calcium carbon- ate were dihbuted to farmers between 1989 and 1993, saving more than $417,000 in lime costs and improving crop yields for soybeans, clover, pasture grass and corn. pH levels increased from 4.5 to 6.4 through use of the lime substitute.

Scarce landfill space was preserved.

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four hours of tests for environmental and

used are regularly tested as well.

\ to dewater the calcium carbonate solids, strength-/ ‘

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waste was reduced by 16 tons/year. In addition, there was less load on the incinerator and less wear and tear on the equipment - the filter cleaning schedule went from twice/month to twice/year.

But there was more to come. In 1991, Chevron implemented a company-wide goal to reduce waste by 25 percent by the end of 1995 (using 1990 as a baseline year). Waste reduction manage- ment teams, established at each plant, were com- prised of operations and maintenance personnel, Responsible Carea coordinators, and environmen- tal, design, project and process engineers. At the Oronite Additives Division plant, Pat Cochran, process engineer; Charleen Dickson, operations supervisor; and Deane Walker, a design engineer; were assigned to examine possible waste reduction projects. Agam, decreasing the amount of unreact- ed phosphorous pentesulfide was suggested.

This time, the team evaluated the production stream and statistically tracked key process parameters while bypassing the acid filter. They discovered that the small amount of unreacted phosphorous pentesulfide in the acid did not

jeopardize the quality of the end product. On the basis of this finding, the production process was rerouted to bypass the filter. As a result, the unreacted phosphorous pentesulfide was reduced another seven tons a year for no investment in capital or re-engineering.

by 50 percent and reduced on-site landfill disposal by 151 tons a year.

For Chevron, the Belle Chasse experience illus- trates that there’s always room for improvement. 1

But there was still more. In 1992, the team identi- fied another waste reduction project for the same production stream. During the acid manufactur- ing step, hydrogen sulfide ( H p S ) was produced as an undesirable by-product. In the subsequent neutralization step, it reacted with zinc oxide to form a solid sediment. This sediment added to the filtration time and waste volume.

The team set its sights on reducing and simultaneously i make the process more effici Jeff Waite, process e Chevron research c

found that the levels uite high but could

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The team felt that regeneration offered the great- est promise to reduce the spent acid. Technical feasibility studies over the course of four years confirmed this. Based on success of the research, a $35 million project was undertaken in 1992 to convert an existing sulfur-burning sulfuric acid plant at Fortier to a regeneration plant that could

and reduced the hazardous process water and effluent discharge to the deepwells by 570 million pounds a year. In addition, the company plans to add a third process waste-gas-to-stream generator to provide complete destruction of organic vapor releases from the acrylonitrile process at the plant.

recovery process.

Within the first four months of start-up in 1994, the plant regenerated more than nine million pounds of spent acid into usable sulfuric acid which was used in other plant processes or sold. This recycling effort alone will enable the Fortier plant to reduce its TRT emissions by 75 percent.

The sulfuric acid regeneration plant is only one of several ambitious waste-reduction projects initi- ated by the Fortier plant. Cytec also built a facility capable of annually recovering up to 12 million pounds of acetonitrile and over one million pounds of hydrogen cyanide from deepwell dis posal, and replaced the stripper column in the acrylonitrile facility which improved operations

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W A S T E T O W A S T E

Recycling Sulfuric Acid - II

Rhone-Poulenc is in the business of recycling sulfuric acid. Its Dominguez, California, plant takes used acid from nearby oil refineries and restores it to like-new condition for resale.

The process involves burning the waste acid, together with sulfur, in an indus- trial furnace. The gases - principally sulfur dioxide - are cooled, cleaned and further processed to produce commercial-grade sulfuric acid. During the process, weak sulfuric acid wastewater is generated.

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Rhone-Poulenc expected some weak acid wastewater when the regeneration unit started up in 1990, but the quantities were much larger than anticipated. The wastewater has to be neutralized on-site before being sent to a publicly- owned treatment works (POW), and larger quantities meant added costs. For the business to be viable, the process needed to operate as close to equilib- rium conditions as possible.

Plant personnel investigated the process throughout 1991 to determine what was causing the excessive weak acid generation. The investigative team looked at half-dozen furnace variables:

Temperature. The furnace temperature was varied between 1,600 and 2,000 degrees Fahrenheit.

Air flow patterns. Different air flow combinations were tried, since combus tion air could be tak5n in through various ports on the furnace;

Acid atomizer locations. There are also numerous ports through which the spent acid can be sprayed into the furnace, and different atomizer spacing arrangements were tried.

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Air flow rate through acid atomizers. The atom- ization air pressure was varied.

Sulfur flow rate and various air configurations. Different sulfur and air combinations were tried.

Different spent acid strengths. Spent acids of different strengths were burned to determine if acid strength had an effect on weak acid generation.

amount of waste acid going to the publicly-owned treatment works by 75 percent. Acid went to acid, and waste was minimized.

In addition, the caustic soda used to neutralize the acidic wastewater was reduced from 3,000 tons to 640 tons, saving more than $500,000 in material cost.

d The team discovered that too much oxygen too early in the process was one of the primary causes of the problem. Instead of sulfur dioxide (SO,) produced in the furnace, sulfur trioxide (SO,) was created. This extra oxygen atom made the difference. When SO, came in contact with water, sulfuric acid was formed.

Armed with this knowledge, the team modified operating procedures to minimize excess oxygen, to raise the burning temperature and to maintain the optimum air flow patterns in the furnace. As a result, Rhone-Poulenc was able to reduce the

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The five-year waste reduction project consisted of three phases. The first two phases focused on the greatest reductions possible with existing equip ment and modest capital spending. Changes in operating procedures were made to reduce the overall volume of waste generated and an off-the- shelf separator was installed. In the third phase, a full-scale separation and recovery process was put in place.

Phase 1. During manufacture, silane gas in a fluid bed reactor moves up through a bed of solids. The gas carries along solids which collect in the bottom of the distillation column. Random pumpout of the silane liquid and suspended solids in the distilladon. column resulted in the large volume of product being thrown away. The team established guidelines for consistent but less frequent batch pump outs of the distillation column, based on operating temperature. This concentrated the solids and reduced the volume of usable silane being discarded by 20 percent.

Phase 2. Next, the Dow Corning team installed several separators after the fluid bed to reduce the volume of solids entering the distillation

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column. This in turn further decreased the amount of usable silane needed to suspend the solids. The first separator was installed in 1989 at a cost of $300,000; a second was installed in 1992 for $350,000 to further optimize batch pumpouts.

Phase 3. The third phase focused on separating the remaining solids from the waste stream in the distillation column and recovering the usable silane. Several chemical reactions were consid- ered to convert the waste, but these alternatives required a solids-free stream. The team consid-

and total dissolved solids will be cut 83 percent. What’s more, Dow Corning will save an estimated $1.7 million in disposal and recovered product costs per year.

The process, with minor variations, can be applied to any waste stream containing fine solids. No new technology was required -just a little creativity and a lot of hard work.

ered other disposal technologies such as incinera- tion and strong-base neutralization, but these would not reduce the waste or recover the good product lost as waste. After evaluating all options and examining both technical and economic fea- sibility, the team chose to filter and dry the solid portion of the waste stream and then recover the liquid silane in the existing distillation equip ment. A separation pilot plant was installed and tested in 1991; the full-scale, $3.1-maon plant was scheduled to come on line in December 1994.

The project is expected to have dramatic results: waste going to landfill will. be reduced 98 percent

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C L E A N I N G

Pots and pans are the biggest problem when doing the dishes - food sticks during cooking, and a strong detergent or extra elbow grease is needed to clean them. So it is when making chemicals, particularly polymers, which can stick like glue to process vessels.

At its Chambers Works plant in Deepwater, New Jersey, DuPont produces a specialized polymer used in aerospace and automotive applications. The poly- mer is made in a pressurized reaction vessel which has an internal agitator and baffles to promote complete mixing of the ingredients. In the course of manu- facture, some of the polymer sticks to all surfaces - the sides, the baffles and the agitator - and must be removed periodically. In addition, the vessel must be cleaned between production runs of different polymer types. On average, the vessel at Chambers Works was cleaned every two weeks.

For 30 years, the cleaning agent was a flammable organic solvent. It smelled - imagine a thousand gallons of oil-based paint drying in a confined space. The solvent was pumped into the vessel, agitated and drained through a bottom flange into 50-gallon drums for incineration. This was repeated several times, resulting in 5,000 pounds of waste per wash, in fugitive emissions and in a dozen drums that were handled partially by hand. Special precautions were required because the fumes could explode. The wash cycle took 24 to 32 hours, and the solvent didn’t remove all of the polymer, which could cause quality problems.

In the late 198Os, a dedicated waste minimization project was authorized to recover and recycle the solvent, and a still was purchased. Before it could be installed, an internal Utility Improvement Team was formed to look broadly

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at process improvement. The team was headed by Richard “Ric” Debski, a transplanted New Englander and graduate of the University of Massachusetts with a degree in chemical engi- neering. The team set several process improve- ment objectives - to minimize waste, to shorten cycle times, to improve quality and to reduce inventories - and considered four alternatives for cleaning the vessel:

Open the vessel and clean it manually. Although this would eliminate the solvent, it would be difficult - the bolts were tightened to a torque 75 times greater than automotive lug nuts, for example - costly and time-consuming, and not attain the other objectives.

Use an anti-stick coating on the vessel. This would reduce cycle time and reduce but not eliminate solvent washes.

Use the still to recycle and recover. Although this would minimize waste, it would achieve no other process improvement objectives. In addi- tion, the original recycling project was based on using drums and, when this was deemed incon- sistent with other objectives, the projected capi- tal costs soared.

Replace solvent wash with a high-pressure water jet. Although this would achieve all the objec- tives, it presented technical and safety prob lems. These waterjets are used to cut rock and steel, and operate at water pressures of 10,000 pounds per square inch (v. 40 pounds for a household shower).

DuPonters - mostly chemical operators and maintenance people, with combined experience of 300 years in the industry - made the process work. The prototype nozzle was tested in April of 1991 and the first system installed in December of that year. A chain drive, operated remotely by an operator several feet away, moves a rotating lance UQ and down inside the vessel. Cleaning takes less

An economic analysis was made of the last two alternatives, with water-jet cleaning a clear choice. Its capital costs were $125,000 v. $500,000 for recy- cling. The net present value - the value over time expressed in today’s after-tax dollars - was a positive $2.7 million for water-jet cleaning and /

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vield loss.

/ ’ The svstem was installed in a second vessel in a negative $350,000 for recycling.

A group came together to address the t e c F a l ,

1992, and in other vessels and processes in problems. For safety, cleaning done remotely, and the

DuPont since then. A joint study published in 1993 bv DuPont and the Environmental

enclosed within the vessel. Protection Agency concludes that “high-pressure water cleaning. now Dresents an environmentallv be limited, preferably to i

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sound alternative [to solvent washes] .” Where water cannot be introduced into the equipment,

Stoneage, Inc., experts in engineering, dry ice can be used.

designed a special cleaning, using swivel

In both cases, waste is cut dramatically. For DuPont at Chambers Works, downtime was cut as well. and a dozen

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In 1987, the McIntosh plant set out to reduce the wastes through process changes and spent the next five years overhauling the process to achieve the waste minimization objectives. Researchers Wolfgang Petri and Jurgen Beyrich developed the new processes in the lab. An operations team, composed of Jack Kimmitt, Wes McConnell, Juan Mani, and Dave Marshall, were responsible for installing the equipment and implementing the new processes in the field’.

The old sulfonation process used 25 percent oleum - a chemical produced by dissolving sulphur trioxide in sulfuric acid - and required dilution and filtration steps. This created the large volume of acid that had to be neutralized in the plant’s wastewater treatment system. In revamping the process, a continuous sulfonation loop was installed, 65 percent oleum replaced the lower concentration, and the purification step was eliminated. The changes increased the concentra- tion of the reaction solution and, as a result, sul- furic acid was eliminated and capacity increased by 30 percent.

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Next, the team focused its attention on the oxida- tion step. Using a different solvent allowed bleach to be replaced by air oxidation utilizing a catalyst. This reduced TOC waste by 70 percent. What’s more, the production yield increased by 17 per- cent and capacity was increased as well. / tion of hydrogen) was substituted for iron r

increase in capacity and a 20-p investment.

CibaCeigy McIntosh’s ave on waste minimiza-

P A Y S

OxyChem, the Occidenlal Chcmical Corporation, produces a herbicide intcr- mediate at the Kiagara Falls, New York, plant, using hydrogen fluoride (HF) a a raw material. In a sequeiicc xs complicated as the house that Jack built:

1) The HF was incompletelv reacted, and part of it lcft the process with byproduct hydrogen fluoridc vcnt gas.

2) This vent p s was converted to muriatic acid containing small amounts of HF; a portion of this acid was used in other plant operations where HF didn’t aflect the process.

3) The unused acid was neutralized to form salt water, which was discharged.

4) But first, the HF in the acid was reacted with lime to form calcium flue ride, which was removed as sludge and disposed of in a non-hazardous landfill.

5 ) Still the effluent discharge contained small amounts of calcium fluoride.

New federal replations required OxyCheni to reduce the amount of calcium fluoride in its effluent. Thc company assembled a group of engineers in 1988 to analyre the problem and develop a solution. The team consisted of William Davis, Technical Program Manager; Thoinas Feeney, Engineering Manager; and Ronald Fostcr, Senior Principal Process Engineer. They identified two options:

Add a settler/filter system. Although this would rcmove solids from thc effluent and would bc chcaper than other options, it would not reduce the amount of sludge generated and sent to landfill.

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Add and change equipment to improve the reaction efficiency of the process. This would eliminate the generation of calcium fluoride sludge and allow complete utilization of the by-product by other processes in the plant.

New equipment was installed, including another reaction vessel, a new acid absorption tower to replace the old one and three 18,000-gallon acid storage tanks. Prior to process modifications, a series of four reactors was used to react the HF; the addition of a fifth reactor greatly increased reaction efficiency and reduced the HF content in the acid and, consequently, eliminated calcium fluoride sludge as well. The usable acid that came from the absorption tower was stored in tanks for use in other processes at the plant. All process changes were approved by the New York State Department of Environmental Conservation in 1990 and were fully implemented in 1991.

19 percent annual return on an initial capital investment of $4.5 million.

The state Department of Environmental Conservation has recognized the company for

waste reduction accomplished through this pro- ject. At OxyChem, it’s business as usual. Since the Niagara Falls plant followed the company’s lead and instituted the OxyChem pollution prevention and waste reduction program in 1989 - called OxyMin - the plant has reduced air emissions by 40 percent, contaminants in water discharge by 70 percent and solid hazardous waste generation by another 60 percent.

tional9,200 tons a year of

material efficiency was effluent flow was reduced

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B E T T E R

Chemical manufacture can be complicated. Making a chemical compound often requires the production of one or several intermediates along the way. The more intermediates, the more chemical reactions and the more opportu- nities for waste.

Such was the case at Monsanto’s manufacturing facilities in the United States and Europe. The plants produce antidegradants for rubber which help tires last longer when exposed to air and ozone.

The production process required three intermediates just to manufacture a key chemical used to make the rubber antidegradants. The process began with benzene, which in turn was converted to:

A) monochlorobenzene; B) paranitrochlorobenzene; C ) 4nitrodiphenylamine; and finally D) 4aminodiphenylamine (ADPA), the desired chemical.

In getting from A to D, significant waste was generated along the way. This included chloride salt which ended up in nearby rivers; xylene, a solvent that was released in fugitive emissions and that was incinerated; and an organic residue which was also incinerated. Monsanto had been concerned about the volume of waste for some time, but the adoption of a formal corporate waste reduction policy in 198’7 placed new emphasis on developing a lower-waste process.

The company designated a research team to analyze the waste problem and develop a proposed plan to reduce waste and cut costs. The team consisted of

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Dr. James K Bashin and Dr. Michael K. Stern, chemists in Corporate Research; and Dr. Roger K. Rains, a chemical engineer and Division Research Manager.

The research team considered several alternatives: recycling the different wastes, selling them and developing a new process. The original process uses solvents and consumes extra raw materials at every step to modify the chemicals and enable them to react with one another in each step. In 1991, Corporate Research conducted a feasibility study of a new process that enabled commercially available raw materials to react directly together without the addition of solvents and without con- sumption of extra raw materials. This meant that Monsanto could eliminate steps A, B and C and go directly from the raw materials to D. Fewer steps meant less waste, which was better for the environment and the bottom line. The only direct by-product of the new process was water.

Once the course was set, a development team took

over: Dr. Roger Rains and Dr. Michael Stern were joined by Chi-Chao Chieng, a chemical engineer and a fellow in process design and Brian Kirtley,

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a chemical engineer and pilot plant supervisor, plus many others. The development team designed an integrated computercontrolled pilot plant which went on-stream in September of 1992. The process was deemed commercially viable in June of 1993, and Monsanto is currently evaluating the timing and economics before scaling up.

There is no question about the environmental impact, however. Waste was reduced on every front - organic waste by 74 percent, inorganic waste by 99.8 percent, SARA waste by 95 percent, process waste water by 98 percent, and net release to the environment (after waste treatment, inciner- ation, etc.) by 98 percent. Chlorid and xylene were eliminated enti consequence was the improvement utilization - the new process uses raw material per pound of ADPA p

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E X P A N D I N G C A P A C I T Y

Dow Corning wanted to expand several processes in its Midland, Michigan plant but coulclri’t because of methyl chloride emission levels from existing processes. The plant makes in terniediatc products called alkoxy silanes, used in a variety of end products such as sealants, rubbers, adhesion promoters, waterproofers and carpet and antifreeze treatmeria.

Methvl chloride is used as a coolant to puritjl hydrogen chloride produced in the alkoxylation process. Both the methyl chloride and the hydrogen chloride are recovered in a subsequent gas recovery svsteni. However, during start-up and shutdown, the gas mixture is vented to water scrubbers. The scrubbers clean the hydrogen chloride but leave methyl chloride that is vented to the atmosphere.

The lack of vent reduction technology posed a big problem to eiwironmcntal standards and to future business plans. The plant wanted to move forward with planned capacity increases, process modifications and new product scale- ups but couldn’t because to do so would requirc new vent permits which would restrict significantly the amount of methyl chloride vented to the atmosphere.

A seven-member team representing engineering and operations personnel tackled the issue in 1992: William Blackwood, project engineer; Kirk Cronin, process engineer; Ray Darby, building tcam leader; Brad House, operations supcrvisor; Jeffrey Kebblish, process design representative; Kevin Maak, project engineer; and,James Smith, manufacturing engineer. Pilot efforts late that year demonstrated &at using a balanced equilibrium heat source - hot hydrogen chloride - at the bottom of the methyl chloride condenser would effectively allow start-up and shutdown without venting methyl chloride to the scrubbet

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The new hot hydrogen chloride gas purge system was implemented in 1993. The system allowed Dow Corning to meet stricter emissions require- ments, which in turn enabled the company to obtain flexible vent permits and commercialize new products. The net results: methyl chloride start-up and shutdown emissions were reduced from 4.1 tons/year to zero and capacity for Dow Corning’s global sealants business increased 60

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percent.

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C O U S I N S

Plastics have had a dramatic impact on life in the 20th century. They have been integral to advances in automotive technology, con$truction, packaging, electronics and medical equipment and clothing. One of the reasons is their infinite variety. Different processes and different starting points can produce a myriad number of plastics that possess the unique strength, weight and other physical properties required for specific applications.

The polypropylene plant at Phillips Petroleum Company’s Houston Chemical Complex produces isotactic polypropylene, rigid in consistency, that is used in consumer products such as packaging, bottles, carpet and woven fabrics. The chemical reaction to produce the plastic depends on a catalyst to jump start it. The old process utilized a relatively low activity catalyst which produced a cer- tain percentage of atactic polymer - a wax-like cousin to isotactic polypropy- lene that is chemically different and not desired in this case - and had to be separated and disposed of. Roughly five to eight million pounds of atactic polymer were generated annually. The stream was flammable and therefore considered hazardous and was incinerated in a waste heat recovery boiler.

Plant management and operations personnel wanted to reduce the volume of atactic polymer to minimize waste and to improve the efficiency of the process. To accomplish this, the company licensed a new high-activity catalyst technolo- gy which significantly increased the yield of isotactic polypropylene. The new catalyst required some redesign of processes and equipment downstream, the most significant of which was an increase in the number of steps to prepare and introduce the catalyst to the process. All equipment changes related to the new catalyst technology were Fully implemented by December of 1993.

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Results were dramatic. The higher activity catalyst eliminated the generation of atactic polymer and enabled plant personnel to shut down the waste heat recovery boiler. What’s more, about 224,000 pounds of permitted pollutants from the boiler stack and other emissions points were eliminated. These reductions represent a 47-percent decrease in total hazardous waste generated at the Houston Chemical Complex, a statistic that stands out. The State of Texas has acknowledged Phillips’ waste reduction efforts as part of the Clean Texas 2000 program.

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S E C O N D L I F E

At its Barberton, Ohio plant, PPG produces a variety of chemicals that depend on chloroformates as major constituents. The resulting chemicals are used in industrial and commercial products including pesticides and pharmaceuticals.

Chloroformates are essential chemical intermediates in the process because of chlorine’s reactivity with the hydrogen at6ms of alcohols, phenols, and amines. However, a gaseous hydrochloric acid stream with a high water content is produced as a by-product. When hydrochloric acid gas is passed through an acid absorber - a waste minimizing step to prevent emissions - a weak acid solution is created. At one time, it was used in another operation at the plant and in the steel industry, but changes in plant operations and the use of a more concentrated acid for steel manufacturing eliminated demand. Since it was no longer a sdeable product, the acid had to be disposed of by underground injection, that is, placing it in EPA-permitted deepwells drilled in special geologic formations. This was costly and wasteful, though environ- mentally sound.

PPG in 1989 targeted the acid stream as a waste minimization project. The project was spearheaded by Process Engineer Jerry Pellet, Project Engineer Manus Narbutaitis and Area Technical Supervisor Dave Souza. The group focused its efforts on optimizing the process to produce a more concentrated acid, which could have a second life as a useful product.

The high water content of the hydrochloric acid stream made it difficult to make a stronger acid. Once the solution got above 18 to 20 percent acid strength, the acid absorber wasn’t effective and acid gas would be released into the atmosphere. This occurred because the water would get hot during

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gas absorption which caused it to vaporize and lose its capacity to absorb the acid gas. The team was challenged to increase the strength of the acid solution and recover all of the acid gas at the same time.

Using a process modeling software package, the team came up with several steps which were added to the acid absorption process. First, a condenser was installed to cool and conaense the water vapors to liquid, increasing acid absorp tion to 25 percent and yielding an intermediate strength acid. Second, the absorber was expanded to strengthen the intermediate acid using the dry gas stream. Finally, the addition of another drying condenser removed even more water, yielding a 32-percent hydrochloric acid that could be sold. The captured water was reused in the closed-loop process.

The new absorption process came on line in March of 1990 and required six months of evalua- tion and modification before it was performing at optimum levels. Disposal of weak acid has been dramatically reduced as a result of the process. A 52-percent reduction in acid disposal was

achieved in 1990; disposal in 1991 and 1992 was 0.02 percent of 1989 quantities. The reduction in waste disposal alone allowed PPG to recover approximately 75 percent of the initial capital cost of the project in the first two years. And the company has profited from selling the acid yield- ed by the process.

The success of the Barberton pl mization project underscores the there is often value in waste.

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The fact that OxyChem worked in tandem with its customer was unique. Once the new process had tested out successfully in-house, and a favor- able economic analysis was assured, the customer tested the paint additive made with the recycled toluene. The final approval on the process was given after successful lab and production trial runs.

The project was successfully implemented by 1993. Waste toluene was reduced from 346,000 pounds in 1992 to 96,000 pounds in 1993. OxyChem expects further reductions in 1994 - to 5,000 pounds a year. The project cost less than $50,000 to implement and saves the company about $80,000 per year -which OxyChem passes on to its customer.

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examining the entire department - covering four city blocks and including hundreds of pieces of equipment. Emissions were measured using a process known as “bagging,” in which a plastic bag or balloon is used to seal off a leaking piece of equipment, containing the leak. The gases trapped in the bag were allowed to escape at the same rate they entered and directed through a flow meter to determine the amount of gases leaking out. Samples of the gases were analyzed using chromatographic analysis to determine their composition. This measurement approach allowed team members to calculate the pounds

consumed in the production process and more acetone was leaving the process in identifed waste streams than previously thought.

Once the sources of acetone leaks were identi- fied, the kam tackled the leakage problems through a combination of equipment and process changes, coupled with workforce training. First,

acetone odors and is encouraged to bring prob- lems and make recommendations for solutions to other team members.

The net result of these steps was that acetone emissions were reduced by over two million pounds in 1991 - double the original goals.

The project had bottom-line benefits for the com- pany as well. By reducing emissions, the company needed significantly less acetone in 1991, saving Union Carbide over $200,000 for acetone and

replacing roughly 10 units with updated e

per year of acetone being emitted at each point‘ of leakage.

The team was surprised by the findings in many cases and gained a better understanding of the production process. Large emissions were found in areas where none were expected, and vice versa. The company had been calculating reportable emissions based on the differecce between the amount to acetone purchased and the amount that left the plant in other products or in waste streams. The team found that an addi- tional 100,000 pounds of acetone were being

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pressor were installed to s the leaking acetone so it

other solvents, which often accompany acetone. collect and rec

igher pressure distillation refrigerated cooling. The process

1 amount of residual acetone,

n important part of the n Carbide credits the

ution prevention efforts ch each employee -

t to be suspicious of the plant manager to each operator on &e

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