An Analysis of Pollution Prevention Opportunities and Impediments in the Chemical and Allied Products Sector in Georgia — Part 3

Sector Profile

Analysis by Sub-Sectors

The variety of processes and materials employed within the chemical and allied products sector have lead to many unique problems associated with the industries within the sector. While there are some common source reduction techniques that can be applied across the sector, the following analysis examines the unique problems of ten homogeneous sub-groupings. The sub-groups are distinguished by their processing characteristics, wastes generated, and product related constraints.

A. Industrial Inorganic Chemicals (281)

The industrial inorganic chemicals group contains four individual SIC codes. The majority of Georgia facilities in this group are listed as SIC 2819, and produce aluminum hydrates, calcium carbonate, hydrochloric acid, iodines, silicates, sulfates, and sulfuric acid. Facilities producing alkalies and chlorine are designated as SIC 2812. The major products of the facilities in SIC 2813 are industrial gases such as acetylene, carbon dioxide, hydrogen, nitrogen, and oxygen. Facilities classified under SIC 2816 are engaged in the manufacture of inorganic pigments such as barium sulfate, chrome pigments, lead oxides, titanium oxides, and zinc oxides.

Geographically, these industries are concentrated in three areas: northwest Georgia, metro Atlanta, and the port areas of coastal Georgia. The facilities are evenly split between batch and continuous processing. Also, half of these facilities are reacting raw materials and half are simply formulating raw materials. There is a significant amount of energy consumption from the heating and cooling of process materials. From the standpoint of materials, processes, and waste, this is a very diverse group.

Waste Generation

The vast majority of the 3.5 million pounds of TRI chemical wastes in 1994 were from SIC 2819. The chemicals most frequently reported are sulfuric acid, hydrochloric acid, phosphoric acid, ammonia, and chlorine. The chemicals are typically used as reactants in the manufacturing processes. The acids are frequently used as formulation components as well. Air releases make up the largest portion of TRI chemical waste generation with ammonia being the most prevalent chemical at 1.5 million pounds.

Figure 5: TRI Chemicals Generated as Wastes in SIC 2819

The manufacture of inorganic pigments results in the generation of metals as waste. Barium, chromium, nickel, and zinc are among the metals reported as wastes in either pure form or as part of compounds. Overall, the quantities reported by SIC 2816 facilities are small. Facilities listed under SIC 2812 and 2813 did not generate significant amounts of the TRI chemicals.

Table 9: TRI Chemicals Generated as Wastes in the Largest Quantities in SIC 281

*Includes wastes reported in the form of the metal and metal compounds

Review of biennial reports indicate the following types of hazardous wastes are generated by these facilities: residues from production operations; residues from spill cleanups; spent solvent from machine shop parts cleaner; corrosive wastes from production processes; filter cake from removal of process impurities; wastewater from various process operations; lab wastes; and contaminated rags, gloves, soil, gaskets, pipe, and other miscellaneous materials. Because most of the hazardous chemicals are used as reactants or formulation components, reaction by-products and residues account for most of the hazardous waste.

Source Reduction Techniques

According to the P2AD survey, the most frequently used techniques were spill and leak prevention and in-process recycling, each of which was reported by 70% of the facilities. Other commonly reported techniques were inventory control, equipment modifications, external recycling, and energy consumption. Because of the diversity of processes in this industry group, there are not a lot of detailed source reduction techniques applicable to multiple facilities in Georgia. Detailed information pertaining to specific processes may be found in the EPA Inorganic Chemical Industry Sector Notebook.

Spill and Leak Prevention

Spill and leak prevention is important for many of the facilities in this group, especially those processing ammonia and chlorine. There is significant emphasis on emission controls for gaseous chemicals such as ammonia and chlorine. Waste is minimized through regular inspection of process vessels, storage tanks, and piping.

In-process Recycling

The recovery and reprocessing of fugitive emissions is a common practice. The reuse of wash water/solutions can also reduce waste.

Process Optimization / Quality Control

Process optimization involves increasing reaction efficiencies which can increase yields and decrease process wastes. Statistical process control, process automation, and operator training can reduce the generation of off-spec materials. Optimize catalysts by examining consumption rates, contacting, and alternative catalysts.

Impediments

According to the P2AD survey, reported impediments to pollution prevention included not economically feasible, regulations, technology limitations, and insufficient capital. No facilities reported the same impediments.

B. Plastic Materials and Synthetic Resins (2821)

Industry group SIC 2821 entails companies involved in the manufacture of plastics and resins. There were 22 facilities listed in the 1994 manufacturers directory; however, 26 facilities reported on the TRI. Four facilities reporting on the TRI were listed under different SIC codes in the manufacturing directory. This is one of two sub-sectors in which all of the facilities are reporting on the TRI. Eight facilities are categorized as large quantity generators. Geographically, the facilities are concentrated around metro Atlanta and coastal Georgia.

Some produced by Georgia facilities are alkyd resins, latex resins, polymer chemicals, polystyrene, polyurea resins, polyurethane foam, synthetic resins, and vinyl compounds. SIC 2821 accounts for virtually all of the styrene generated in the sector. Styrene is used as a reactant or formulation component in at least half of the facilities. Other frequently used raw materials include acrylic acid, ammonia, ethylene glycol, formaldehyde, glycol ethers, maleic anhydride, methanol, sulfuric acid, and zinc compounds.

Equipment cleaning is done with either acids or solvents. Sulfuric acid and hydrochloric acid were used at six facilities. The solvents used include xylene, methyl ethyl ketone, 1,1,1-trichloroethane, and 1,2,4-trimethylbenzene.

Waste Generation

While the quantities of TRI chemicals generated by plastics and resins manufacturers has decreased by 40% over the past four years, this group remains one of the most significant in the sector. In comparison with the rest of the sector, SIC 2821 has the highest portion of TRI chemicals released by air at 36%. Transfers account for 63%, while less than 1% of the chemicals generated are released to water or land.

Figure 6: TRI Chemicals Generated as Waste in SIC 2821The use of 1,1,1-trichloroethane, trichlorofluoromethane, xylene, and methane has decrease substantially over the past four years as shown in Table 8. In part, this reflects a switch to solvent such as methyl ethyl ketone and N-methyl-2-pyrrolidone (NMP). The generation of the main reactants and formulation components as TRI wastes has remained steady. A review of the biennial reports indicates the following types of wastes: cleanup from spills and leaks; off-spec and expired materials; unreacted monomers; process wastewater; process solvent waste; filters; spent carbon from wastewater treatment and air pollution control; off-spec product; and lab wastes from quality control activities and bench scale research.

Table 8: The TRI Chemicals Generated in the Largest Quantities

Source Reduction Techniques

Common source reduction activities reported in this group include spill and leak prevention, process optimization, and in-process recycling. Because of the fact that many of the raw materials used are highly volatile, the storage, handling, and processing of these chemicals can greatly impact the rate of fugitive emissions.

Spill and Leak Prevention

Since VOCs such as 1,3-butadiene, chlorobenzene, methanol, 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.

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 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

Vapors of styrene and solvents can be recovered for reuse. Equipment cleaning waste may be reused in some manner. If styrene is used as the solvent, the solvent wash can be collected, stored, and reused in the next batch of the same product, displacing virgin styrene. If that is not possible, the spent solvent wash can be recycled with a solvent distillation unit.

Alternative Cleaning Methods

While materials in this industry group are difficult to clean with chlorinated or aromatic solvent replacements, one alternative which has used successfully in some cases is N-methyl-2-pyrrolidone (NMP). A low vapor pressure solvent, dipropylene glycol monomethyl ether (DGME) has been used as a substitute for methyl ethyl ketone and xylene. Heated caustic solutions can work in limited situations. 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 and steam jennies.

Inventory Control

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

Impediments

Impediments reported in the P2AD survey include: projects were not economically feasible, insufficient capital, product quality, and limited in-house expertise.

C. Drugs (283)

Industry group 283 is made up of manufacturers of medicinal chemicals (SIC 2833), pharmaceutical preparations (SIC 2834), diagnostic substances (SIC 2835), and other biological products (SIC 2836). Products listed by Georgia facilities include cold preparations, dermatologicals, diagnostic substances, feed additives, lens care products, medicinal chemicals, ointments, and vitamins.

With 18 facilities listed in the 1994 manufacturers directory, this group is small in comparison to the others. In 1994 there were three facilities reporting on the TRI, and in 1993 four facilities were biennial reporters. The vast majority of facilities are located in the metro Atlanta area. The number of larger facilities is proportionally higher in this group with nearly half listing over 100 employees. Another unique characteristic is the impact of the Food and Drug Administration (FDA) regulations. Manufacturing in this group is primarily batch processing with a heavy dependency on solvents. There are also a number of more research oriented operations with small scale manufacturing.

Waste Generation

The wastes generated by these facilities are similar to others engaged in batch processing operations. The total amount of TRI waste generated in this group was 2,443,299 pounds in 1994. This is a 45% decrease from 1991. Most of the decrease was in the form of air emissions which dropped 88% from 1991 to 1994. The vast majority of the TRI chemicals are accounted for by transfers as shown in Figure 7.

Figure 7: TRI Chemicals Generated as Wastes in SIC 283

Methanol is the most prevalent of the TRI chemical wastes. About 1.5 million pounds were generated by the three TRI facilities, but only five percent of that was released to the environment. Other priority chemicals of importance are xylene and dichloromethane shown in Table 11. Methanol is used extensively in the manufacturing process. As a reactant, methanol is part of a chemical reaction which results in another substance or product. Methanol is generated as a waste in unreacted process materials and fugitive (leaks and spills) emissions. Frequently, methanol is also used as a processing aid, where it is added to the reaction mixture as a process solvent. In this case the methanol does not react or become consumed by the reaction; instead, the spent methanol solution is generated as a waste stream. Finally, methanol is commonly used at the completion of a batch to clean the processing equipment. This also generates a spent methanol solution as a waste stream. Other solvents, like xylene, dichloromethane, and toluene, are used for processing and cleaning as well.

Table 11: The TRI Chemicals Generated in the Largest Quantities

Wastes in this industry are commonly generated as fugitive releases (leaks, spills, etc.), off-spec product, expired or contaminated raw materials, empty containers with residuals, air (VOC) emissions, laboratory analysis waste, solvent waste and wastewater from equipment cleaning, filters, soiled rags, and contaminated clothing.

Equipment cleaning process varies depending on whether the formulation is dry or wet. Cleaning is necessitated when product formulations are changed. 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.

Liquid formulations can be either water or solvent based. 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, producing a wastewater stream.

Source Reduction Techniques

In the areas of material storage and handling, spill and leak prevention, inventory control, and alternative packaging are important techniques. For many of the operations that use batch processing, effective source reduction techniques are production scheduling and quality control.

Spill and Leak Prevention

Volatile organic compounds (VOCs) and dusts are the air emission concerns of the industry. Much of the reductions in air emissions can be attributed to better storage, handling, and processing of VOCs such as methanol, dichloromethane, and xylene. Reductions in emissions in storage are the result of using floating roofs, gas blanketing the storage tanks, chilling the tanks, and using refrigerated condensers. 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.

Production Scheduling

As discussed in section II.C., production scheduling can be used to effectively reduce waste by reducing cleaning. Trade-offs may be higher inventory costs and more capital expenditures on equipment.

Quality Control / Process Optimization

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 / Procedure Changes

There is limited opportunity to reduce waste through the reuse of materials. Solvents can be collected and reused in applications that are not strictly regulated by the FDA. 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 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.

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. 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.

Alternative Packaging

Raw materials are received in a variety of containers from small bags to a tank truck. Solid waste can be reduced by working with vendors to use returnable containers or containers which can be readily recycled.

Impediments

The main impediment to source reduction in the pharmaceutical industry results from limitations placed on manufacturers by the Food and Drug Administration (FDA). The safety of drug substances are established through the specification of specific materials, equipment, and chemical processes approved by the FDA. For instances, solvents, which are used in the process to remove impurities, must conform to the designated kind and purity for each particular manufacturing process. While the reuse of spent solvent would reduce waste, it is prohibited because of the possibility of contamination. The substitution of a solvent would require extensive laboratory and clinical evaluations of both the manufacturer and customer to gain FDA approval. FDA regulations also restrict utilization of techniques such as raw material substitution, process equipment modifications, and operating procedures changes.

Case Study SIC 283

This is a medium size (approximately 100 people) facility which produces a variety of pharmaceutical products. The plant is a batch production operation with batch times varying from one day to a couple of weeks. The company has a corporate environmental policy and pollution prevention program. The program has detail objectives, waste stream assessments, waste stream prioritization, alternative screening, feasibility evaluation, a waste minimization committee, and employee training.

Figure 8: TRI Chemical Generation

There are a variety of waste streams whose composition depends on the product being manufactured. Chemical wastes are generated during the manufacturing process and equipment cleaning. Several manufacturing processes generate liquid waste streams with methanol, ethyl acetate, methyl acetate, toluene, and xylene as possible constituents. Equipment cleaning involves use of xylene, methanol, toluene, and ethyl acetate as solvents. Other non-hazardous wastes include sludge from water treatment plant, spent activated carbon, packaging materials, crushed fiber drums, paper, cardboard, plastic wrap, Styrofoam, pallets, metals, filter media, wastewater, and construction waste.

Source Reduction Techniques

Source reduction alternatives which have been evaluated include alternative cleaning procedures, process modifications, reuse of materials, and waste segregation. Some methanol and isopropyl alcohol is distilled for reuse where not limited by FDA regulations. Storage tanks are purged with nitrogen to control emissions. Raw material vapors are condensed, processed, and reused. Aggressive investigation of the causes of spills, leaks, and other fugitive releases has resulted in preventive measures. Pollution prevention has also been addressed through operating procedures, employee training, and spill prevention/emergency response guidelines. Emissions of toxic chemicals were reduced 85% over a five year period.

Impediments

The facility evaluated the possibility of reusing process and cleaning materials, but found that FDA regulations prohibited them from doing so. Any process or material change would require FDA approval which was cost prohibitive. The recovery of solvents used in the process to remove impurities by distillation was investigated, and even though the recovered solvent was essentially the same as procured solvent, it would require clinical testing of the products to gain FDA approval.