An Analysis of Pollution Prevention Opportunities and Impediments in the Chemical and Allied Products Sector in Georgia — Part 5

G. Fertilizers (2873, 2874 & 2875)

Industry group 287 consists of agricultural chemical manufacturers. This group will be separated into producers of fertilizers (SIC 2873, 2874 & 2875) and pesticides (SIC 2879). Facilities in SIC 2873 produce nitrogenous fertilizers such as ammonia, ammonium nitrate, nitric acid, and urea. SIC 2874 are manufacturers of phosphatic fertilizers such as ammonium phosphate and phosphoric acid. Facilities that only blend fertilizers are listed under SIC 2875. Most of these facilities are located in the agricultural areas of middle and south Georgia.

The production of nitrogen-based fertilizers begins with natural gas, air, and steam. Natural gas and steam are reformed to produce hydrogen and carbon monoxide. Ammonia can then be reacted with carbon dioxide to produce urea. Ammonia is reacted with air to produce nitric acid. Ammonium nitrate is produced by reacting ammonia and nitric acid. Ammonium phosphate is produced from a reaction of anhydrous ammonia, phosphoric acid, and sulfuric acid.

Blending of fertilizers occurs in small batch process operations. Either liquid or solid formulations can be made, and then packaged for end use. The processing equipment includes blend tanks, piping, pumps, mixers, mills, conveyors, and hoppers. Aqueous equipment cleaning is most often used.

Waste Descriptions

About 98% of the TRI chemical waste generated is in the form of ammonia or ammonium nitrate. By media, the split is roughly even between air and water. Almost all of the ammonia and ammonium nitrate waste is from the manufacture of the base materials. The formulation and packaging operations contribute a very small amount to the overall TRI volume.

Figure 16: TRI Chemicals Generated as wastes in SIC 2873,74,75

Some common wastes listed in the biennial reports are: contaminated or otherwise unusable raw materials; empty containers; spills, leaks, and other fugitive releases; off-spec product; laboratory analysis waste; and wastewater from equipment cleaning. Fugitive releases of ammonia and ammonium nitrate account for most of the volume. In the formulation operations, equipment cleaning, material handling, and packaging are activities which generate waste.

Table 16: TRI Chemicals Generated as Wastes in the Largest Quantities in SIC 2873,74,75

Source Reduction Opportunities

In the P²AD survey, fertilizer producers (SIC 2873 & 2874) reported inventory control, in-process recycling, process optimization, and spill and leak prevention as frequently used source reduction techniques. The fertilizers mixers (SIC 2875) reported using spill and leak prevention, in-process recycling, and external recycling.

Spill and Leak Prevention

The storage, handling, and processing of the materials are critical to controlling emissions. Regular inspection and maintenance of piping, pumps, valves, process vessels, storage tanks, and containers can effectively minimize material losses. A wet scrubber and condensate stripper are commonly used to recover and recycle ammonia.

Production Scheduling

For fertilizer blending, scheduling production into longer runs of the same formulation reduces the need to clean equipment between batches. Products with similar formulations can be scheduled together as well. Scheduling in this manner also promotes better operational efficiency, though inventory costs may be increased. Refer to section II.C. for further details.

In-process Recycling

Ammonia and ammonium nitrate emissions can be captured and reintroduced to the process. Cleaning wastes can also be reused in future formulations. The use of the same material in the formulation as the cleaning agent allows the cleaning waste to be reused later in the make-up of the same product formulation. Most of the liquid formulations use water, thus the rinse water could be reused. With dry formulations an inert material such as clay or sand can be used to flush out the process equipment. This material can later be reused as the inert carrier in the next batch. Residues in equipment can be removed prior to rinsing by the use of wiper blades or squeegees. These residues can be collected and reused. The volume of cleaning waste can also be reduced by using low volume high efficiency cleaning systems, such as high pressure spray nozzles, water knives, and steam jennies.

Process Optimization / Quality Control

Significant waste reductions can be achieved through better quality control. The use of statistical process control, automation, and employee training can lead to a more efficient operation. Because the cost of generating off-spec material includes the cost of the raw materials, all the labor and overhead costs associated with processing that material, and the disposal costs, it is quite apparent that this is an area that can provide significant economic benefits.

Alternative Packaging

Small volume packaging of fertilizers can result in solid wastes. The use of returnable containers for raw materials, and washing drums for reuse or recycling can help reduce waste.

Impediments

Impediments reported in the P²AD survey include insufficient capital, not economically feasible, product quality, limited in-house expertise, technology limitations, and regulations. There were no commonly expressed impediments.

H. Pesticides (SIC 2879)

The pesticide formulation industry includes preparers of insecticides, herbicides, and fungicides. These products may be used in agricultural, industrial, and household applications. The facilities in SIC 2879 are primarily engaged in formulating pesticides for end use. Facilities primarily engaged in manufacturing the chemicals are listed in industry groups 281 and 286.

Geographically, these facilities are near the agricultural areas in middle and south Georgia. Many of these facilities are large in terms of numbers of employees; however, these operations are more labor intensive than the rest of the sector. The operations usually consist of formulating active and inert ingredients in batches, and packaging the products into containers of various sizes for end use. Products can be either in liquid or solid form. Liquid solutions are based on solvents or water, and solid formulations may use clay, sand, or a treated bait. Equipment cleaning is done with either solvents or aqueous solutions.

Waste Generation

The TRI chemicals of concern are either pesticides or solvents which are used in the formulation of products. Solvents are also used to a limited extent in cleanup. While the total amount of TRI chemical waste has decreased since 1991 as shown in Figure 17, the amount reported as air releases has increased. Some of the major TRI chemicals are listed in Table 17.

Figure 17: TRI Chemicals Generated as Waste in SIC 2879

A review of biennial reports indicate the following wastes are common: contaminated or expired raw materials; solvent rinsate contaminated with pesticides from system clean out; pesticide contaminated wastewater from system clean out; lab sample waste; pesticide contaminated absorbent from spill cleanup; damaged containers contaminated with pesticide; contaminated protective clothing; spills and VOC emissions, and off-spec materials and customer returns. Of these waste streams, equipment cleaning is probably the largest generator of waste. Cleaning is necessitated when switching production to different formulations. The cleaning process varies depending on whether the formulation is dry or wet.

Table 17: Profile of Significant TRI Chemicals Generated as Waste in SIC 2879 (quantity in pounds)

With liquid formulations the equipment used includes a mixer tank, transfer lines, and pumps. Cleaning can be accomplished with either high pressure water, a steam jenny, or solvent flush. For a solvent-based formulation, cleaning is normally accomplished by rinsing with the same solvent used in the product formulation. This spent solvent can be reused later in a production run with the same formulation. The solvent rinse is then followed by a water rinse, which produces a wastewater stream. Pressurized rinsing or using a steam jenny also results in a wastewater contaminated with pesticide.

Equipment used in making dry formulations includes blending mills, conveyors, and hoppers. An inert material such as clay or sand can be used to flush out the process equipment. This material can later be reused as the inert carrier in the next batch. Additionally, vacuum systems are used to collect dusts generated from processing dry materials.

Source Reduction Techniques

The P²AD survey indicated several waste minimization activities in this group. Spill and leak prevention, inventory control, in-process recycling, raw material substitution, and external recycling were methods mentioned by half of the respondents.

Inventory Control

Many of the ingredients and products have a limited shelf life which can cause them to become unusable. Efficient management of purchasing and production activities can prevent the expiration of materials and reduce waste.

Production Scheduling

Scheduling production into longer runs of the same formulation reduces the need to clean equipment between batches. Products with similar formulations can be scheduled together as well. Scheduling in this manner also promotes better operational efficiency, though inventory costs may be increased. Refer to section II.C. for further details.

In-process Recycling

Reuse of cleaning wastes can also aid in pollution prevention. The use of the same material in the formulation as the cleaning agent allows the cleaning waste to be reused later in the make-up of the same product formulation. The cleaning agent may be a solvent or water for wet formulations, or a solid for dry formulations. If the cleaning waste cannot be reused in the formulation, it may be possible to reuse it in subsequent cleaning operations. For instance, a stagewise cleaning process could be used where the first pass is made with old cleaning waste (solvent, water, clay, sand, etc.), and a second pass is made with fresh material. Multiple rinses can then be made with the “dirty” and “fresh” cleaning agents. Eventually, the first rinse material will need to be disposed of and replaced with the cleaner material from the first rinse. Cleaning in this manner can reduce the waste volume generated.

Dry Cleaning Methods

Heavy residue in equipment can be moved prior to rinsing by the use of wiper blades or squeegees. This can also help reduce the volume of rinse material necessary. Low volume high efficiency cleaning systems, such as high pressure spray nozzles, water knives, and steam jennies, can significantly reduce the amount of cleaning waste generated.

Process Optimization / Quality Control

Significant waste reductions can be achieved through better quality control. The use of statistical process control, automation, and employee training can lead to a more efficient operation. Because the cost of generating off-spec material includes the cost of the raw materials, all the labor and overhead costs associated with processing that material, and the disposal costs, it is quite apparent that this is an area that can provide significant economic benefits.

Spill and Leak Prevention

Because anything that comes in contact with pesticides has the potential of becoming hazardous, waste prevention is of the utmost importance. Dry cleanup with absorbent pads can help reduce hazardous waste once a spill has occurred. Major sources of fugitive emissions are dust and VOCs. Dust collection systems that serve all production lines or products with a common baghouse generate a waste that is most likely hazardous. An alternative is to segregate dust collection so that there is no cross-contamination, and the dust can be returned as a raw material in a subsequent batch. VOC emissions are a common problem with storage. Some ways to reduce emissions in storage are using floating roofs, gas blanketing the storage tanks, chilling the tanks, and refrigerated condensers.

Alternative Packaging

Many of the pesticide materials are received and shipped in drums, which creates a disposal problem. Some alternatives include receiving raw materials in returnable tote bins, triple rinsing the drums so that they may be reused or recycled, or using plastic liners that can be disposed of instead of the drum.

Impediments

Survey results indicated that product quality/integrity, technology limitations, and limited in-house expertise were common impediments to implementing source reduction practices. Most facilities have little or no on-site engineering staff to work on pollution prevention. The effectiveness of the training program is reduced by high turnover and the lack of technical capabilities in the labor force. The inability to economically justify automated production systems makes good operating procedures and employee training more important.

While production scheduling would be a desired method to accomplish source reduction, there are several factors that make it difficult to implement. First, the wide variety of products with limited shelf life limitations necessitates manufacturing on an as needed basis. The unpredictability of demand is another contributing factor.

Case Study (2879)

This is a pesticide manufacturing facility which employs 120 people. The company has an environmental policy and a waste reduction plan. The facility has been doing an increased amount of contract manufacturing, and less formulation under their own label. This has resulted in a change in the type of products and waste that is generated. They have experienced an increase in demand for solvent-based products and a decrease in demand for water-based products.

The pesticide products are formulated using a batch process. Raw materials are piped from holding tanks to mixing kettles where the formulations are made. The pesticide formulations are sent to a container filler line where the product is packaged for distribution.

Wastestream Descriptions

The primary waste generating activity is equipment cleaning. This involves rinsing out kettles, tanks, fillers, and piping. The process begins with water or solvent sprayed through special nozzles into the mixing kettle. The rinsate is then circulated through the kettle pipes and filters. Next, the rinsate is pumped from the kettle to the holding tank. The lines are then air blown clear. From the holding tank, rinsate is pumped through the filler lines where it exits the system.

At this point, a sample is taken to analyze pesticide content. The system is rinsed until no contaminants are detected, and then the next formulation can be made. If the rinsate can be reused in a future pesticide formulation, it is drummed and labeled to identify which product. Rinsate that cannot be reused is disposed of as hazardous waste. The rinsate will either consist of water with pesticide residues or petroleum solvents with pesticide residues.

Other wastes include absorbent materials with pesticide residues from spills and damaged containers. Waste can also result from mis-formulations and expired materials.

Source Reduction Techniques

In order to try to reduce cleaning waste, the facility reviewed and changed cleaning procedures. Air blowing of the lines is now done prior to and after system flushing. This helped to reduce the amount of rinsate generated. When possible, the rinsate or flushate is collected and reused in future batches. This requires identifying and storing the flushate. Water flushate is reused in the next formulation of that water-based product, and solvent flushate is reused in the next formulation of that solvent-based product.

Prior to the implementation of source reduction, clay was used to cleanup spills, which, consequently, had to be disposed of as hazardous waste. To reduce the volume of hazardous waste from cleanup, the facility switched to using absorbent pads. The pads are be wrung out and reused, thereby reducing the amount of hazardous waste that must be disposed.

Impediments

The unpredictable demands and increased variety of products from contract manufacturing make it difficult to schedule similar products back-to-back and reduce system clean-outs. Product shelf-life limitations prohibit storing pesticides for an extended period; thus product must be made as needed. Another impediment to source reduction is turnover in the workforce and the limited qualified local labor force. Waste is often generated by a worker who mixes incompatible rinsates or misreads a formulation. High turnover has also reduced the effectiveness of the training program. A manufacturing process that maximized automation and minimized man-power requirement would be the preferred approach; however, the capital expense of an automated production system makes it unfeasible as an immediate solution.

I. Adhesives and Sealants (2891)

Industry group SIC 2891 includes manufacturers of adhesives, caulking compounds, epoxy adhesives, glue, joint compounds, laminating compounds, paste, rubber cement, and sealants. This is a significant industry group in Georgia with 31 facilities mostly located in the Atlanta metropolitan area.

These facilities are typically small with 80% having less than 30 employees. The manufacturing operations are primarily batch formulation. Raw materials include animal and vegetable products, solvents, and plastics. Materials are received in bags, drums, tote bins, and tanker trucks. The adhesives are made by blending ingredients in batch mixing tanks. Products are shipped in tote bins, drums, or smaller consumer packaging. Most facilities produce a wide variety of products necessitating frequent cleaning of equipment.

Waste Generation

TRI chemical waste generation has remained relatively constant over the past four years. Air releases account for two-thirds of the total generated. Transfers are about one-third with water and land being insignificant. Most of the TRI chemicals are solvents used as formulation components in the adhesive. Some solvent is used in equipment cleaning. A few facilities use acrylates as reactants in their processes.

Figure 18: TRI Chemicals Generated as Wastes in SIC 2891

There has been a recent trend in the industry to produce adhesives with lower solvent content. According to the 1991 TRI, nine facilities reported 1,1,1-trichloroethane and six reported toluene, whereas in the 1994 TRI only two facilities reported 1,1,1-trichloroethane and three reported toluene. Aqueous cleaning, reported by 60% of the survey respondents, is more prevalent than solvent cleaning. The facilities producing water-based adhesives have generally eliminated solvents from their facilities and do not report on the TRI. Table 18 shows TRI chemicals and their uses in the processes.

A review of the biennial reports indicate the following types of waste: off-spec raw materials; residuals from equipment clean out; off-spec products; lab wastes from samples and expired chemicals; and waste cleaning solvents.

Table 18: Profile of Significant TRI Chemicals Generated as Wastes in SIC 2891

Source Reduction Techniques

According to the P²AD survey, this industry group has been very active in the area of waste minimization with 70% of the facilities indicating at least four waste minimization activities. Spill and leak prevention, process optimization, process equipment changes, in-process recycling, external recycling, and alternative packaging were techniques reported to be used by at least half of the respondents. Waste minimization assistance received by this group is nearly all from corporate management and vendors.

Spill and Leak Prevention

Since VOCs such as cyclohexane, dichoromethane, glycols, methyl ethyl ketone, and toluene are emission concerns of the industry, much attention needs to be given to the storage, handling, and processing of these materials. Selection and maintenance of storage, transfer, and processing equipment can effectively minimize losses. Employee training is also critical to prevention efforts.

Inventory Control

Many of the ingredients and products have a limited shelf life which can result in them becoming unusable. Efficient management of purchasing and production activities can prevent the expiration of materials and reduce waste.

Raw Material Substitution / Alternative Product Design

The most effective way to eliminate VOCs is to replace the solvents used in the products and cleaning agents. Several companies in the industry have considered source reduction in the design of their products. Some examples are listed in Table 19.

Table 19: Selected Product Reformulations for Adhesives

Adapted from Stirring Up Innovation: Environmental Improvements in Paint and Adhesives, John S. Young, Linda Ambrose, Lois Lobo, INFORM, Inc., New York, New York, 1994.

Production Scheduling

Scheduling production into longer runs of the same formulation reduces the need to clean equipment between batches. Products with similar formulations can be scheduled together as well. Scheduling in this manner also promotes better operational efficiency, although inventory costs may be increased. Refer to section II.C. for further details.

Process Optimization / Quality Control

Significant waste reductions can be achieved through better quality control. The use of statistical process control, automation, and employee training can lead to a more efficient operation. Because the cost of generating off-spec material includes the cost of the raw materials, all the labor and overhead costs associated with processing that material, and the disposal costs, it is quite apparent that this is an area that can provide significant economic benefits.

Process Modifications

Tank washing systems can greatly affect the amount of solvent needed to clean tanks, and the amount of waste generated. High pressure spray nozzles can increase the effectiveness of a tank washing system. Tanks and mixers can be pre-cleaned with squeegees or wipers. Use of wipers can increase the yield by recovering adhesive left in the equipment and reduce the amount of solvent needed for washing. The use of rubber “pigs”, as described in the case study in this section, can increase yields and reduce wastes.

In-process Recycling

Equipment cleaning wastes may be reused in some manner. By using the same solvent as in the formulation, the solvent wash can be collected, stored, and reused in the next batch of the same product. If that is not possible, the spent solvent wash can be recycled with a solvent distillation unit.

Alternative Packaging

Bulk transportation of raw materials via tank truck or tote bins can reduce solid wastes associated with drums and bags. Working closely with vendors is an effective way to minimize packaging wastes.

Impediments

The most common impediment from the P²AD survey was that projects were not economically feasible. Equipment cleaning systems that replace solvents require significant capital investment. The wide variety of products manufactured make it difficult to use production scheduling to minimize wastes. Many of the raw materials and products have limited shelf lives which constrain the ability to carry inventory and reuse materials.

Case Study (SIC 2891)

This is a manufacturer of water-based adhesives employing approximately 25 people. A batch process is used to produce the adhesives. Raw materials are received by tank trucks, drums, and bags. These materials are formulated into approximately 100 different products. Adhesive products are loaded into tank trucks, tote bins or drums for shipment to the customers. Batches are produced in mix tanks ranging in size from about 300 to 5,000 gallons. Boilers are used to generate steam for heating production batches and boil-out water. After each production batch, the process equipment requires cleaning which is accomplished with hot water and agitation. The amount of water used for a boil-out depends on the tank, and the cleaning time varies between one to three hours.

Tote cleaning is done manually through the use of water hoses, shovels, and scrappers. Tote bins are usually returned with a small amount of semi-dried residue. However, sometimes they are returned nearly full. Totes with more than a few inches of residual product are shoveled out. Sometimes it is necessary to fill the tote with hot boil-out water to loosen up dried residuals. The adhesive products have a limited shelf life; therefore, it is difficult to reuse returned material.

Wastestream Descriptions

Since the facility eliminated solvent-based adhesives and the use of solvents for cleanup, the main wastestream of concern is wastewater containing solids and BOD. As a wastestream, water is generated from batch cooling and cleanup. Cooling water at ambient temperature is passed once through the tank jackets to cool production batches, and then is discharged. Also, there is a loss of energy, since the discharge temperature is usually in excess of 140^oF. In the process of heating batches, a small amount of condensate is generated. This condensate is currently discharged in the same manner as the cooling water.

The wastewater from cleanup activities is either boil-out water or tote and floor washing water. Cleaning the tanks and the tote bins generates a large volume of wastewater and consumes a significant amount of energy in the form of steam. The boil-out water contains adhesive solids and is typically near 195^oF when discharged. The pH may vary anywhere from 3.5 to 10 depending on whether the product is alkaline or acidic.

The tote bin cleaning wastewater is similar to that from the boil-outs, although it is usually not heated. The floor around the tanks and the product loading area is washed down frequently. The operators use open-ended hoses to wash the floor and the tote bins.

Adhesive residuals are a solid waste. Unsalable product, process losses, and residual solids from tote cleaning are the main sources. Unsalable product is out-of-spec materials or customer returns. Process losses result from pump leaks and changing filters in the tote loading line. The used filters also become a waste. The remaining solid wastes are packaging materials, and include damaged tote bins, drums, cardboard, bags, and pallets. Lost heat and excessive energy consumption is also considered a waste.

Source Reduction Techniques

The products were redesigned to eliminate hazardous solvents by changing to water-based formulations. This also enabled the facility to then eliminate the use of 1,1,1-trichloroethane in equipment cleaning. Heated water and agitation are now used to clean instead of solvents. The facility no longer generates TRI chemicals as seen in Figure 19.

Figure 19: TRI Chemical Generation

To a limited extent, the same or similar batches have been scheduled in sequence to minimize tank cleaning. Changes in operating procedures have decreased process losses by allowing residues to settle in the tank after it is emptied and by recovery of material lost during filter changes. Quality control has been used to decrease the production of off-spec materials which resulted in fewer customer returns and less waste adhesive. Drums and pallets are being reconditioned for reuse. Cardboard is recycled. Repairs to the boiler and improvements in the efficiency of the boiler operation have conserved energy.

Impediments

The use of tote liners was investigated to eliminate wastewater from tote cleaning, but was found to increase operating costs. Tank and tote washing systems were analyzed to reduce cleaning wastes, but have not been implemented due to unavailability of capital. The limited shelf life and variety of products has made it difficult to reduce waste through longer production runs.

J. Printing Inks (2893)

Industry group SIC 2893 includes manufacturers of letterpress, flexographic, lithographic, gravure, offset, and screen process inks. The average size of a facility is about 20 employees. Nearly all of the ink manufacturing is centered in the Atlanta metropolitan area.

Ink manufacturing is done by blending the ingredients in small batches. Raw materials are received in small to intermediate sized containers such as bags, pails, buckets, drums, and tote bins. Consumer packaging is drum size or smaller. The product variety necessitates frequent cleaning of equipment. The P²AD survey indicated that solvents were used as cleaning agents in 80% of the facilities, and aqueous cleaning was used in 40% of the facilities.

Waste Generation

The quantity of TRI chemical wastes generated has decreased dramatically over the past four years. This has been particularly the case in the area of air emissions, which are almost solely VOCs. As a portion of the total waste generated, the percentage of chemical releases to the air has declined from the seventy percent range in 1991 and 1992, to less than twenty percent in 1994. This indicates that the facilities have become much more effective at preventing fugitive releases. The elimination of 1,1,1-trichloroethane and reduction of other solvents as seen in Table 20 is responsible for this change. Also, higher flash point solvents, such as terpenes, have replaced traditional ones.

Figure 20: TRI Chemicals Generated as Waste in SIC 2893

Barium, cobalt, copper, lead, and other metals contained in pigments can cause ink wastes to be hazardous. A review of the biennial reports indicate the following types of hazardous wastes: solvent rinsate from equipment cleaning; off-spec and obsolete ink product; and solvent sludge from solvent recovery units.

Table 20: Profile of Significant TRI Chemicals Generated as Waste in SIC 2893

Source Reduction Techniques

In the P²AD survey, inventory control, raw material substitution, in-process recycling, external recycling, and alternative packaging were each reported to be used by at least half of the respondents.

Spill and Leak Prevention

Since VOCs such as ethylbenzene, glycol ethers, methyl ethyl ketone, toluene, and xylene are emission concerns of the industry, much attention needs to be given to the storage, handling, and processing of these materials. Selection and maintenance of storage, transfer, and processing equipment can effectively minimize losses. Employee training is also critical to prevention efforts.

Inventory Control

Many of the ingredients and products have a limited shelf life which can result in them becoming unusable. Efficient management of purchasing and production activities can prevent the expiration of materials and reduce waste.

Raw Material Substitution / Alternative Product Design

The most effective way to eliminate VOCs is to replace the solvents used in the products and cleaning agents. Several companies in the industry have considered source reduction in the design of their products. Water and soy-based inks are becoming more common. There are also less toxic pigments available which do not contain hazardous metals.

Production Scheduling

Scheduling production into longer runs of the same formulation reduces the need to clean equipment between batches. Products with similar formulations can be scheduled together as well. Scheduling in this manner also promotes better operational efficiency, although inventory costs may be increased. Refer to section II.C. for further details.

Process Optimization / Quality Control

Significant waste reductions can be achieved through better quality control. The use of statistical process control, automation, and employee training can lead to a more efficient operation. Because the cost of generating off-spec material includes the cost of the raw materials, all the labor and overhead costs associated with processing that material, and the disposal costs, it is quite apparent that this is an area that can provide significant economic benefits.

In-process Recycling

Off-spec ink and other material losses can be blended into a low grade product. In this manner, some of the material value is recovered and disposal costs are avoided. Equipment cleaning wastes may be reused in some manner. By using the same solvent as in the formulation, the solvent wash can be collected, stored, and reused in the next batch of the same product. If that is not possible, the spent solvent wash can be recovered with solvent distillation unit.

Alternative Packaging

Bulk transportation of raw materials via tank truck or tote bins can reduce solid wastes associated with drums and bags. Working closely with vendors is an effective way to minimize packaging wastes.

Impediments

Impediments listed in the P²AD survey included product quality, projects were not economically feasible, insufficient capital, and technology limitations. Customer resistance to low solvent and soy-based inks is an impediment to VOC reduction. Water-based inks have had a difficult time gaining acceptance in some areas of the markets. Many of the facilities are small and do not have engineering capabilities on-site. None of the respondents indicated that they received help with waste minimization from external sources such as consultants, university programs, or government.

Case Study (2893)

This is a manufacturer of printing inks. The facility employs 24 people. The company has an environmental policy and a waste reduction plan. There are two basic ink manufacturing processes used at this facility. The first is referred to as paste ink manufacturing. It begins with the blending of the raw materials into a paste. The raw materials used include solvents, resins, and pigments. After the addition of each raw material, the ink base is milled into a finished ink product.

The other process is referred to as fluid ink manufacturing. In this process, the ink is either alcohol or water-based. The pigments and other raw materials are blended into the ink base. The ink is then milled into the finished product.

Wastestream Descriptions

There are four hazardous waste streams at the facility listed in Table 21. The constituents of concern in the hazardous wastes are barium, chromium, methyl ethyl ketone, and toluene. Out-of-spec ink materials result from operator mistakes, equipment problems, and poor quality raw materials. Expired raw materials and expired ink product are another wastestream.

The equipment cleaning process generates a mixture of ink tailings and solvent. Most solvent wash from equipment cleaning can be run through a solvent reclamation unit. The distillate is then reused as solvent. The still bottoms which consist of ink and solvent residues are a wastestream.

Table 21: Hazardous Wastes Generated at the Facility (quantities in pounds)

Source Reduction Techniques

There were several changes which helped reduce the hazardous waste generation by 50% from 1989 to 1993. Improvements in inventory control and purchasing management have virtually eliminated the occurrence of out-dated materials. This was accomplished through regular review of current stock and production needs. Also, employee training was necessary to ensure the appropriate use of materials.

The use of barium, chromium, and lead pigments was eliminated. This decreased the toxicity of waste ink materials. Out-of-spec ink was reduced by using Statistical Process Control (SPC) to ensure ink quality and prevent defects. Also, some out-of-spec material was able to be reused in future production batches.

Production scheduling has helped to reduce the frequency of equipment cleaning. This resulted in less solvent wash being generated. Housekeeping improvements continue to decrease the amount of solvent needed to clean equipment. Employees have been trained to first remove ink tailings by scraping and use less solvent to clean-up. An effort has been made to decrease the use of solvents with flash points below 140 F to decrease air emissions and hazards.

Product research and development will continue to play an important role in waste minimization. Originally, the manufacturing processes were all solvent-based. Now, there are several water-based and soy-based products.

Impediments

There are a variety of impediments to source reduction that have been experienced. Customer specifications and delivery demands are a primary impediment. The product specifications limit the ability to change ink formulations and eliminate the use of hazardous materials. The unpredictability of customer orders and delivery requirements limit the ability to use production scheduling as a pollution prevention tool. Changing employee behavior can sometimes be an impediment. For example, higher flash point solvents require more physical man-power when cleaning, which makes them somewhat unpopular with employees.