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Aerosolv® Serves Our Country

The Navy's naval operations in Norfolk Virginia needed a system to manage the diversity and volume of aerosol can recyclables. The Aerosolv® system met the challenge.

U.S. Navy's Final Report Aerosolv® Technology Field Test Demonstration


I. BACKGROUND

Aerosolv entered into an agreement with the U.S. Environmental Protection Agency (EPA) and the California Environmental Protection Agency for federal verification and state certification of the Aerosolv® technology.

The technology consists of an aerosol can puncturing/draining device that is threaded into the large bung hole at the top of a 55-gallon drum; a coalescing filter assembly that is threaded into the small bung hole of the drum; and a 30-gallon drum carbon filter canister, see enclosure (1) of Appendix I.

Liquids discharged from the puncturing/draining device are collected in the collection receptacle. Non-condensable gases and volatile fractions are diverted through the coalescing filter and adsorbed onto the carbon. Empty cans resulting from the process are recycled as scrap metal.



In November of 1996, Aerosolv approached the U.S. Navy for assistance in developing and performing the Field Test Demonstration outlined in the Field Test Plan. Aerosolv selected the Navy for five reasons:

  1. The Navy is the largest generator of hazardous waste aerosol cans in California.
  2. California Assembly Bill 483 authorized hazardous waste aerosol can generators to use certified aerosol can recycling technologies without extensive permitting or authorization requirements. Commander Naval Base, San Diego (CNBSD) and the Navy Public Works Center (PWC), San Diego, Environmental Department were searching for an aerosol can recycling technology manufacturer who would be willing to obtain certification in the State of California. CNBSD and PWC offered to provide a test demonstration site, a large inventory of aerosol cans, and the labor to operate and test the Aerosolv® technology.
  3. The Navy generates a larger variety and diversity of aerosol can products than any other industrial user in California.
  4. The Navy was instrumental in the development of the Aerosolv® technology at the Naval Operations Base in Norfolk Virginia.
  5. CNBSD and PWC are extremely cognizant of the regulatory issues associated with aerosol can management. For further discussion of regulatory status, please see discussion at the end of this document.


PWC began conducting the Field Test Demonstration in accordance with the approved Field Test Plan on August 5, 1998. The test concluded on November 19, 1998. This document summarizes the results of the demonstration conducted by the Navy.

II. FIELD TEST OBJECTS


  1. Removal
    Removal of hazardous waste to 3% of capacity: Determine the ability of the technology to remove hazardous waste such that less than 3% of the original capacity of hazardous waste remains. This is consistent with the federal definition of an empty container.
    The results indicated that 98.6% of the cans contained less than 3% residual by weight of the total capacity after puncturing. This residual was comprised of both hazardous and non-hazardous material.

    Removal of hazardous waste to the maximum extent practical: This is consistent with California's specific aerosol can regulations for hazardous waste. California developed specific regulations for aerosol cans because none existed previously.
    DTSC and PWC representatives noted that each of the cans processed were emptied to the maximum extent practical.

    Removal efficiency: Determine the 90% confidence limit of the mean removal efficiency.
    The test results indicated that the Aerosolv® technology captured 95% of the total product discharged. Removal efficiency calculations are presented in Appendix XIII.


  2. System Capture Efficiency

    Determine the percent of gaseous and liquid contents removed from the processed cans that is captured by the Aerosolv® technology.

    Mass balance discharge and Aerosolv® system collection results indicated that 95% of the materials discharged were removed and captured by the Aerosolv® technology.


    1. CARBON FILTER EFFECTIVENESS

      a. Determine the total mass of the contents of aerosol cans processed by the Aerosolv® technology resulting in carbon filter breakthrough emissions and the mass resulting in carbon filter changeout in accordance with criteria established in the Field Test Plan.

      For each type of material processed, an analysis was conducted to calculate the cumulative number of grams discharged when the carbon filter exhaust monitor reached 100,000 ppm. Not surprisingly, the values varied depending on the material; indicating that there is no obvious or direct correlation of mass discharge and filter saturation. For the five filters utilized during the paint processing, the filters emitted 100,000 ppm at an average of 16,800 grams of paint discharged. For corrosion preventative compound (CPC), 42,000 grams was discharged prior to the first filter emitting 100,000 ppm. The 100,000 ppm threshold was not reached on the second CPC filter after 35,000 grams was discharged. The filter for the Brakleen® never reached the 100,000 ppm threshold even though 46,000 grams was discharged through the unit. In fact, the Brakleen® filter never exceeded an exhaust emissions reading in excess of 3.88 ppm.

      Target compounds were not detected at the 90% carbon filter effectiveness (100,000 ppm) threshold established in the Field Test Plan for carbon change-out. As such, a more appropriate basis for determining carbon change-out is when emissions of target compounds from the carbon bed exhaust are detected in the breathing zone at concentrations exceeding Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs). This action point for carbon changeout was never reached during the field test. Based on Field Test results, PWC recommends that carbon changeout occur after continuous or sustained processing well in excess of 2,000 cans (for more detailed information see Appendix XIII).



      b. Measure the total organic vapor concentrations in carbon filter breakthrough emissions and assess their risks to worker health and safety.

      With respect to any emissions coming off of the carbon filter, no target compounds were found at laboratory reporting limits; thus the emissions were propellants. Health risks associated with the propellants are identified in Table 1, Enclosure (3), of Appendix I. Monitoring results support the conclusion that employees were not exposed above OSHA PELs, National Institute of Occupational Safety and Health (NIOSH) recommended exposure levels (RELs) or American Conference of Governmental Industrial Hygienist (ACGIH) RELs.



      c. Assess the adequacy of the established standard operating procedures in determining when the carbon filter needs replacement.

      The standard operating procedure for the Aerosolv® unit recommends changing the filter when the granules contained within the colorimetric indicator change color from magenta to black. The manufacturer designed the indicator to be sensitive to the target compounds and not to propellant gases. As noted in the field logs the colorimetric indicator was monitored during the Test Runs and changes in color were observed. At no time was any indicator observed to turn black. These observations support the field monitoring data that target compound saturation was never reached. At the 100,000 ppm threshold carbon beds were still effective in capturing target compounds and minimizing worker health and safety concerns (see specifically the Brakleen® Test Runs). PWC recommends that additional language in the SOP clarify that the colorimetric indicator color change is gradual, but saturation is not indicated until it turns black.



    2. ASSESS WORKER HEALTH AND SAFETY IN OPERATING THE AEROSOLV® TECHNOLOGY

      a. Determine the capability of the Aerosolv® technology to operate such that the vapor/gaseous emissions within the operator's breathing zone do not exceed the allowable daily exposure.

      Workplace monitoring results indicated that PWC employees were not exposed to vapor/gaseous emissions within the operator's breathing zone above OSHA PELs. Breathing zone exposure results are contained in Appendix I, Section 3 of the Report.



      b. Determine the capability of the Aerosolv® technology to operate such that the vapor/gaseous emissions within the operator's breathing zone do not exceed other regulatory limits.

      Workplace monitoring results indicated that PWC employees were not exposed to vapor/gaseous emissions within the operator's breathing zone in excess of other occupational exposure limits recommended by NIOSH and ACGIH. Breathing zone exposure results are contained in Appendix I, Section 3 of the Report.



      c. Determine the potential for emissions from operation of the Aerosolv® technology to exceed 10% of the LEL.

      Workplace monitoring results indicated that 99.96% of the total data points collected were less than the lower explosion action limit (LEL) of 1% (10,000 ppm). LEL monitoring results are contained in Appendix I of the Report.



      d. Determine the effectiveness of the technology in preventing releases of the liquid contents of the aerosol cans.

      During the preliminary test run (Break-In Run) respirators, safety glasses, and gloves were utilized. During this preliminary test the process was evaluated to determine appropriate levels of personal protective equipment required for the remainder of the Test Runs. While protective safety glasses and gloves were maintained throughout the balance of the Test Runs, the emissions data indicated it was unnecessary to maintain the respirator throughout the tests. While safety glasses and gloves were utilized, no significant splashing or spraying was observed. A total of 2,267 cans were processed in a total of 4,130 minutes.


III. FIELD TEST RESULTS


Objective 1a: Removal of Hazardous Waste to 3% of Capacity

PWC began collecting aerosol cans for the Field Test Demonstration in November of 1996. Over 25,000 cans were collected and segregated according to class, family, and species as indicated in the PWC Standard Operating Procedure #931-96-006, Aerosol Can Management. Due to changes in the development of the Field Test Plan and regulatory restrictions regarding treatability studies and the storage of aerosol cans, the cans were sorted and inventoried on three separate occasions. The final segregation and inventory was conducted in response to the November 20, 1997 Draft Field Test Plan. As a result of that segregation and inventory process, PWC provided a list of the various types and constituents contained in each can to be evaluated. DTSC had originally proposed that:

  1. Test Run #3 be conducted solely on So-Sure Lacquer Green 14110
  2. Test Run #5 be conducted on either Eco-Sure or So-Sure paint
  3. Test Run #4 be conducted on Eco-Sure Gray Spray Paint 16099
  4. Test Runs #6 and #7 be performed on Aerokroil penetrating oil
  5. Test Runs #8 and #9 be performed on Polytech® TG-452 aerosol cleaner


PWC personnel segregated the paints into Eco-Sure and So-Sure paints and demonstrated that the each type of paint contained similar constituents. PWC also demonstrated that So-Sure CPC was more prevalent than Aerokroil and Brakleen® was a more prevalent than TG-452. As a result, PWC requested and received verbal permission to:

  1. Evaluate any approved type of So-Sure paint in place of the green lacquer
  2. Evaluate any approved type of Eco-Sure paint in place of the gray spray paint
  3. Substitute So-Sure CPC for Aerokroil
  4. Substitute Brakleen® for TG-452


Aerosolv further requested that the field test evaluate 3-25% full cans as opposed to full cans as originally requested by DTSC. Aerosolv made this request because in the real world, very few cans in the spent aerosol can waste stream are more than 25% full. In fact, most are 3% to 15% full. However, because of time constraints, and with the approval of DTSC, full cans were processed through the carbon beds. In fact, DTSC representatives requested the processing of full cans during Test Run #1 (Eco-Sure paint). DTSC later revised the Field Test Plan to incorporate these requests.

PWC performed Test Run #1 on 352 Eco-Sure High-Solids enamel paint cans and Test Run #2 on 1132 So-Sure paint cans. At the conclusion of Test Run #2, PWC requested to bypass Test Run #3 based on the length of time required to conduct the previous tests, the shortage of Eco-Sure High-Solids enamel paint cans with between 3% and 25% residual prior to puncturing, and the apparent collection of sufficient data. DTSC permitted PWC to proceed with Test Run #4 while it evaluated the need to conduct Test Run #3.

At the conclusion of Test Run #4 DTSC decided that Test Run #3 was necessary and further requested that PWC not proceed with any other Test Runs until 75 paint cans were randomly selected and cleaned for tare weight determination. PWC personnel consulted with DTSC representatives and selected 100 post-treated cans from Test Run #2 for the purpose of cleaning and tare weight determination. These cans were collected in a separate box and put aside. DTSC representatives then assisted PWC personnel in selecting an appropriate can opener and observed the can opening and cleaning process.

During the cleaning process, PWC and DTSC representatives realized that the polymerized paint solids adhered to the side of the cans was extremely difficult to remove. At that time PWC inquired as to the validity of including the weight of this dried, solid, polymerized, non-hazardous material in the tare weight determination. PWC argued that the 3% criteria outlined in 40 CFR 261.7 did not include non-hazardous material. The polymerized paint solids discovered were definitely non-hazardous.

As such, in accordance with page 4 of the Field Test Plan, PWC requested that the tare weight procedure be modified because it was inadequate with regards to the verification process. Specifically, the procedure as written included the weight of this non-hazardous residue.



Paint

First Evaluation: So-Sure paint cans from Test Run #2, deficient of exterior paint, tape, labels, or other discretionary debris, were selected in the presence of DTSC personnel to ensure the integrity of the tare weight results. Over 1100 So-Sure paint cans were evaluated. The majority of these cans contained less than 15% product (estimated based on pre-treatment weight) prior to treatment. These cans were collected over a period of two years. PWC selected So-Sure paint because the chemical formulation of So-Sure paint represents the most common type of paint used both commercially and by the military.

The random selection process resulted in evaluation of So-Sure paint cans with post-treatment weights less than 110 grams. This sampling represented 60% of the total So-Sure paint can pool. The cans selected had post-treatment weights ranging from 96.32 grams to 109.96 grams, a variance of 13.64 grams. Original nominal capacity weights ranged from 283 grams to 361 grams with an average of about 300 grams. Given that the lowest post-treatment weight recorded for the entire paint can pool was 94.00 grams, it was reasonable to suspect that the tare weight of the paint cans would probably be less than 94.00 grams. Further, using an average nominal capacity weight of 300 grams, one could quickly determine that 3% of the original contents would equate to approximately 9.0 grams.

Based on these preliminary calculations, PWC hypothesized that cans with post-treatment weights in excess of 103 grams (94 grams of tare weight plus 9 grams of residual) would not meet the 3% criteria. Therefore, 33 of the 75 cans would not meet the 3% criteria. PWC further hypothesized that the residual percentage would increase linearly as the post-treatment weights elevated above 94.0 grams. As such, a can registering a post-treatment weight of 97.0 grams would maintain a 1% residual volume, a can registering a post-treatment weight of 100.0 grams would demonstrate a 2% residual volume, a can registering a post-treatment weight of 103 grams would demonstrate a 3% residual volume, and so on. As such, PWC expected over 40% of the So-Sure paint cans randomly selected to retain residual volumes in excess of 3% because their post-treatment weights exceeded 103 grams.

Tare weight results (provided in Appendix II) did not support our hypotheses. Over 75% of the cans were emptied by the Aerosolv® technology to less than 1.5% of their original capacity. Over 90% of the cans were emptied to less than 2.0% of their original capacity. All of the cans were emptied to less than 3.0 % of their original capacity. Further, the results showed no relationship between post-treatment weights and percent residual remaining. Cans with post-treatment weights of 102 grams had percent residual volumes between 1.3% and 1.8%, while cans with average post-treatment weights of 109 grams had percent residual volumes between 0.4% and 1.8%.

Definite trends highlighted by the results indicate that the percent residual remaining in the can is truly a function of the can and the technology design. During the processing of each can, DTSC and PWC representatives noted that the design of the Aerosolv® technology puncturing device punctures the can just above the lip formed at the top of the can. The contents of the can are allowed to drain through the hole; however, the cup that's created captures material collected in the lip of the can. This minimal volume of material is consistent for each can. Therefore, the percentage of material that remains becomes a function of the total original capacity of the can and not of the technology's ability to empty specified types of material. Analysis of the tare weight results indicates that all seven cans with percent residual volumes over 2% had total original capacities less than 300 grams.



Second Evaluation: DTSC selected a combination of Eco-Sure and So-Sure cans for the second tare weight evaluation. The cans selected were as follows: 19 Eco-Sure High-Solids enamel paints form Test Run #1, 43 So-Sure paint cans from Test Run #2, and 13 Eco-Sure High-Solids enamel paints from Test Run #3. Eco-Sure High-Solids enamel paint cans from Test Run #1 contained less than 15% material prior to puncturing (estimated based on pre-treatment weight) and were collected over the course of two years after discard. The nature of the So-Sure paint cans selected was described above. Eco-Sure High-Solids enamel paint cans selected from Test Run #3 also contained less than 15% material prior to puncturing (estimated based on pre-treatment weight). However, these cans were only collected over the course of one month after discard. PWC personnel segregated and collected the cans for Test Run #3 from cans that were recently relinquished because they had previously run out of Eco-Sure High-Solids enamel paint cans that they deemed appropriate for evaluation. In addition, three basic differences exist between the Eco-Sure High-Solids enamel paints and the So-Sure paints:

  1. Eco-Sure High-Solids enamel paints are military specification paints made specifically for the military. Commercial users are unable to obtain high solids content paints of this nature
  2. Eco-Sure High-Solids paint cans are lined with a protective internal coating. This coating was removed during the can cleaning process because paint stripper was used to remove the polymerized solids adhered to the protective coating. Therefore, the weight of the protective coating, which should be added to the tare weight of the can, is lost in the calculation
  3. Eco-Sure High-Solids enamel paints have two shaker balls per can as opposed to one in most cans. Two balls may be used to ensure proper dissolution of the additional solids present in the can.


Tare weight determination procedures were outlined and agreed upon by DTSC, Aerosolv, and PWC, Appendix IV. Tare weight results supported the conclusions established in the first tare weight evaluation of So-Sure paint cans, Appendix V:

  1. 88% of the cans were emptied by the Aerosolv® technology to less than 1.5% of their original capacity
  2. Only one can exhibited a post-treatment residual volume greater than 2.5%
  3. All of the cans exhibited post-treatment residual volumes less than 3.0%
  4. Can number 273, the can with the highest post-treatment weight also had the highest tare weight: 116.83 grams
  5. Can number 750, the can with the second highest residual volume (2.34%) had one of the lowest post-treatment weights: 103.91 grams
  6. Can number 992, the can with the second highest post-treatment weight (113.23) had one of the lowest residual volumes: (0.47%)


In evaluating the military specification Eco-Sure High-Solids enamel paints, it was reasonable to suspect that the residual volume would be greater than that for the commercially common So-Sure paints. Aerosolv and PWC questioned the validity of evaluating a product whose use is primarily limited to military applications. However, the parties agreed that utilizing data obtained from tests performed on these cans would provide valuable insight as to the capabilities of the Aerosolv® technology. Aerosolv and PWC also suspected (as discussed above) that cans of high-solids paints that were stored in a near-empty capacity for sustained periods of time would polymerize internally. In this case, one could not re-suspend the solids and they would be unavailable for application as a coating. Consequently, they would also be unavailable for discharge during aerosol can puncturing and draining. Therefore, these cans would retain a greater volume of residual than cans whose solids that did not have an opportunity to polymerize internally. Aerosolv and PWC hypothesized that aerosol cans were not completely impervious to air and that oxidation and polymerization took place inside the cans. If this theory were valid, the residual results for Eco-Sure High-Solids enamel paint cans from Test Run #1 would be drastically different than those from Test Run #3. DTSC and PWC representatives witnessed part of this phenomenon when they investigated Eco-Sure High-Solids enamel paint cans immediately after puncturing and discovered that the cans had in fact allowed polymerized solids to adhere to the sides of the cans. PWC representatives noticed the phenomenon to a greater extent when comparing the amount of polymerization found in Test Run #1 cans to the lesser volume found in Test Run #3 cans. Evaluation of the tare weight results further highlighted the effect:

  1. All 13 cans from Test Run #3 exhibited tare weight residual volumes between 0.8% and 3% with an average around 1.5%
  2. Cans with higher post-treatment weights demonstrated lower residual volumes (compare cans #10, #97, #122, and #132 to cans #44, and #45)
  3. Five cans from Test Run #1 exhibited post-treatment residual volumes in excess of 3%. Two of these cans appeared to be missing a shaker ball and their tare weight results are suspect
  4. The 14 cans remaining had tare weight results between 0.8% and 3.0% with an average around 2.0%
  5. Cans from Test Run #1 had noticeably more polymerized solids adhered to the internal protective coating and the outside of the tube

All of the Eco-Sure High-Solids enamel paint cans were emptied to the maximum extent practical; however, it was apparent that the Test Run #1 cans retained more residual volume than the Test Run #3 cans. Additionally, Test Run #1 cans were noticeably more difficult to clean than either Test Run #2 or Test Run #3 cans. Based on these observations, and in light of the fact that DTSC and PWC representatives witnessed polymerized solids adhered to the side of cans that were cut open immediately after puncture, PWC concluded that polymerization does indeed occur in aerosol cans during sustained storage.



Corrosion Preventative Compound

First Evaluation: For purposes of the first tare weight determination, PWC randomly selected 75 cans from one kind of CPC (Mil-C-81309E, Type III, Class 134A) to ensure the integrity of the tare weight results. This particular type of CPC is a military specification product containing chlorofluorocarbons (CFCs) that have been otherwise banned from commercial use.

Tare weight results indicated that percent residual volumes consistently ranged between 0.3% and 0.6% regardless of post-treatment weight. These data further support the data trends discussed with regards to paint cans. In this case, the type of material and the original total capacity of the can remained constant. Therefore, the only variable was the effect of the technology. From the results, PWC concluded that the technology consistently empties cans with liquid-only components to less than 1% residual.


Second Evaluation: Five types of CPC were evaluated during the Field Test Demonstration: Mil-C-81309D, Type II, Class 2; Mil-C-81309E, Type II, Class 134A; Mil-C-85054A, Type I, Class A; Mil-C-85054B(AS), Type I, Class 134A; and Mil-C-81309E, Type III, Class 134A. From these types DTSC selected 20, 18, 16, 5, and 15 cans respectively. Mil-C-85054B(AS), Type I, Class 134A and Mil-C-8504A(A3), Type I, Class A contained barium sulfate and were expected to demonstrate much greater residual volumes than the other types. All of the CPC types are military specification materials and contain CFC propellants. Materials with CFC propellants are no longer manufactured for applications outside of military applications. As such, the CPC products selected do not represent common commercial use. However, the selection of these products for the Field Test Demonstration assisted the research team in evaluating the effectiveness of the carbon filter and potential occupational health exposure.

Tare weight results indicated that CPC cans that did not contain barium exhibited residual volumes between 0.2% and 1.2%. These results were consistent with the results obtained in the first tare weight determination. CPC cans that contained barium exhibited residual volumes between 0.5% and 2.0%. These results were also consistent with expected results.


Brakleen

PWC randomly selected 75 cans of Brakleen, cleaned the cans with a naphtha solvent, allowed the cans to dry, recorded the tare weight results of each can, and determined the percent residual volume of each can. Tare weight results indicated that percent residual volumes consistently ranged between 0.3 and 0.5% regardless of post-treatment weight. These results paralleled the CPC results with one exception: more Brakleen cans demonstrated percent residual volumes around 0.3%.


Conclusion

Based on the demonstration results, the Aerosolv® technology has successfully demonstrated that it facilitates the emptying of aerosol cans to less than 3% residual as defined by this objective.

The design of the Aerosolv® technology facilitates discharge of in excess of 97% by weight of the capacity of aerosol cans processed. The actual percentage of residual remaining in the can is a function of the technology and the can design. In this Field Test, three types of products were evaluated. For each type of product, the volume of liquid captured in the lip of the can was similar, approximately 0.5 cubic centimeters. However, the average percentage of residual remaining in the can for Brakleen® was less than that for CPC, which was less than that for paint. Ironically, the total original capacity by weight for Brakleen® exceeds that for CPC by over 100 grams. The original capacity by weight for CPC exceeds that for paint by over 150 grams on average. Because the paint total capacity is significantly less than the CPC or the Brakleen® , the percent residual by weight remaining in the paint cans is greater (see discussion in the conclusion for Objective 1c below). However, in every case, the weight captured in the lip of the can is minimal and for 98.6% of the cans evaluated, the residual volume constitutes less than 3% of the total original capacity.

Of further interest, five of the 375 cans evaluated during this tare weight determination process that exhibited residual volumes greater than 3%, contained non-hazardous residuals that were present in a non-hazardous form prior to puncturing. All five cans were military specification Eco-Sure High-Solids enamel paint and all five were stored for up to two years in a near-empty capacity. In addition, the residual volume calculation for two of the five cans was suspect.



Objective 1b: Removal of Hazardous Waste to the Maximum Extent Practical

The Aerosolv® puncturing/draining device is designed to receive inverted aerosol cans. This design promotes drainage of the contents of the can into the collection receptacle and coalescing filter as appropriate. The puncturing pin places a hole just above the lip of the can through which the contents are allowed to escape. The evacuation process is quick and efficient. Cans are depressurized and emptied to the levels represented in Objective 1a. Investigation of the processed cans allows one to quickly determine that the cans are emptied to the maximum extent practical. See Appendix XII for more detail.


Conclusion

Based on the demonstration results, the Aerosolv® technology has successfully demonstrated that it removes the contents of aerosol cans to the maximum extent practical.



Objective 1c: Removal Efficiency

The Field Test Plan was developed to ensure that the results obtained during the Field Test met the 90% confidence limit of the mean removal efficiency. Data from each aerosol can product class was obtained from the processing of the 375 cans described in the discussion for Objective 1a. The tare weight of each can was subtracted from the pre-treatment weight of each can to determine the weight of material contained in each can prior to processing (original content weight). The tare weight of each can was then subtracted from the post-treatment weight of each can to determine the weight of material that was not removed from the cans (residual weight). The resulting residual weight was then subtracted from the original content weight to determine the weight of material actually removed (removal weight). The removal weight was then divided by the original content weight and the result was multiplied by 100% to determine a removal efficiency.


Conclusion

Field test results indicate that the removal efficiency objective is not a valid objective for purposes of this demonstration. Removal results indicated that 95% of the materials contained in the cans were removed. Corresponding removal efficiency results indicate a removal efficiency of 75%. There is no obvious correlation between removal efficiency and the Aerosolv® Technology's performance. As noted in the conclusion for Objective 1a, the minimal volume of residue remaining in each of the cans after processing was the same despite the volume of material residing in the can prior to processing. For example, a full can containing 400 grams of original content material was emptied such that only 2 grams of residual remained in the can. The removal efficiency for this can is 99.5%. Conversely, a 3% full can containing 12 grams of original content material was also emptied such that only 2 grams of residue remained. However, the removal efficiency for this can is only 16.6%. In both cases, the cans were emptied to the maximum extent practical and to 0.5% of the original full capacity of the respective cans by weight.



Objective 2a: Determine the Percent of Gaseous and Liquid Contents Removed from the Processed Cans that is Captured by the Aerosolv® Technology.

DTSC, Aerosolv, and PWC developed a mass balance equation that compares the sum of all of the aerosol can contents removed to the total weight added to the Aerosolv system. The sum of all contents removed was determined by subtracting the sum of all post-treatment weights from the sum of all pre-treatment weights per test run. The total weight added to the Aerosolv system was determined by subtracting the sum of all pre-treatment weights from the sum of all post-treatment weights per component assembly. To ensure accuracy and precision, a 200-kilogram capacity drum scale, accurate to within +/- 0.1 kilogram and a laboratory balance accurate to within +/- 0.01 grams were used. Further, to determine system capture efficiency to the desired accuracy, approximately 45 pounds were collected by the Aerosolv® collection system.

The greatest challenge DTSC and PWC faced with this approach was volatilization. Because most aerosol components are extremely volatile, DTSC and PWC representatives observed weight losses of 0.1 to 0.3 pounds per day from the collection receptacle and the carbon filter unit. To offset these losses, weighing procedures were modified to include record keeping at periodic intervals not less than once per day. However, they could not account for immediate losses.

The detailed calculations of the total mass discharged per can for each Test Run are included as Appendix VI. Total mass discharge results are presented in Appendix VII. Mass capture results reflecting the total mass captured by the Aerosolv® recycling technology for each Test Run are provided in Appendix VIII. PWC calculated the total mass of material discharged from each can per test run from Appendix VII. PWC then calculated the total mass of material captured in the Aerosolv® recycling technology collection system from Appendix VIII. The total mass of material captured was then subtracted from the total mass of material discharged. The resultant mass was then divided by the total mass of material discharged to obtain a percent variance. The variance was subtracted from 100% to obtain a percent capture, Appendix IX.


Conclusion

The Aerosolv® technology effectively captured 95% of the contents of the aerosol cans processed. As such, the Aerosolv® technology has successfully demonstrated that it captures greater than 90% of the gaseous and liquid contents from the processed cans.



Objective 3a: Determine the total mass of the contents of aerosol cans processed by the Aerosolv® technology resulting in carbon filter breakthrough emissions and the mass resulting in carbon filter changeout in accordance with criteria established in the Field Test Plan

For each type of material an analysis was conducted to calculate the cumulative number of grams discharged when the carbon filter exhaust monitor reached 100,000 ppm. The detailed calculations are included as Appendix X. The total mass collected per carbon bed filter is included as Appendix XI. Not surprisingly, the values varied depending on the material. For the five filters utilized during the paint processing, the filters emitted 100,000 ppm at an average of 16,800 grams of paint discharged. For CPC, 42,000 grams was discharged prior to the first filter emitting 100,000 ppm. The 100,000 ppm threshold was not reached on the second CPC filter after 35,000 grams was discharged. The filter for the Brakleen® never reached the 100,000 ppm threshold even though 46,000 grams was discharged through the unit. In fact, the Brakleen® filter never exceeded an exhaust emissions reading in excess of 3.88 ppm. The significance of these findings is as follows:

  • The filter effectively adsorbs target compounds. The Brakleen® test runs were designed to test the effectiveness of the carbon bed filters on products that were solely or primarily comprised of target compounds. Perchloroethylene was selected because it is widely recognized as one of the most common carcinogens in use today. Perchloroethylene has an extremely low PEL and low RELs. The carbon bed filters associated with the Brakleen® cans demonstrated no breach of integrity after 46,418.02 grams of Brakleen® were discharged.
  • For paint, which is comprised primarily of non-target compounds (containing approximately 1% of target compounds on average), the carbon filters emitted 100,000 ppm when approximately 16,800 grams were discharged. No target compounds were detected. The carbon bed filter results associated with the processed paint cans support the conclusion that the emissions detected at the 100,000 ppm threshold are propellants (LPG's: propane; butanes; dimethyl ether). The results are also in agreement with the anticipated performance of the coconut carbon. Specifically, coconut carbon has a lower affinity for LPG propellants (0.3% by weight) and target compounds will displace LPGs. Therefore, the carbon bed filters associated with the processed paint cans were still effective after processing 16,800 grams of paint.
  • For CPC, which is comprised of about 40% target compounds, the carbon filter emitted 100,000 ppm when 42,000 grams were discharged for one filter and never reached the 100,000 ppm threshold when 35,000 grams were discharged on the second. In both cases, monitoring results indicate that these emissions did not contribute to the employee's overall exposure burden. Further, no target compounds were found at laboratory reporting limits. As such, the monitoring results support the conclusion that employees were not exposed above OSHA PELs, ACGIH RELs, or NIOSH RELs. Refer to Appendix I, Section 3, Carbon Bed Area Samples, of the Report for more details.
  • There is no obvious or direct correlation of mass discharge and filter saturation. The carbon bed filters associated with each of the test runs did not reach saturation and can continue to be used effectively. The 100,000 ppm threshold selected for purposes of this Field Test Demonstration is an extremely conservative threshold that is more than adequately protective of human health and the environment.

Conclusion

A more appropriate basis for determining carbon change-out is when emissions of target compounds from the carbon bed exhaust are detected in the breathing zone at concentrations exceeding OSHA PELs. As stated previously, this action point for carbon changeout was never reached during the field test. Based on Field Test results noted above, PWC recommends that carbon changeout occur after continuous or sustained processing well in excess of 2,000 cans (see Appendix XIII).



Desorption Factor

A situation that complicates fully resolving this objective is that organic vapors desorb significantly off the carbon bed when not in use. This is supported by emissions activity measured by the exhaust TVA for each carbon bed prior to resuming can processing. The details of this desorption activity are summarized in the Workplace Monitoring Report. In general, exhaust TVA readings were always higher from a used carbon bed after the bed sat undisturbed. The most significant variances were associated with cans containing less than 40 grams of product prior to introduction into the Aerosolv® technology. The desorption data reported below is excised from Workplace Monitoring Report Chart #6.


Date Carbon Bed Can Content Start TVA End TVA
8/6/98 #1 varied   33.2
8/7/98   several full 115  
8/10/98 #2 several full   300
8/11/98   varied 37,2000  
8/19/98 #3 3-25%   41,500
8/21/98   3-25% 178,350  
8/25/98 #4 3-25%   295
9/2/98   3-25% 20,000  
9/22/98 #9 full   29
9/22/98   full 270  


This information may suggest that when processing fuller cans the propellant remains associated with the liquid material, whereas emptier cans may be comprised of more propellant than liquid material. Henry's Law may explain such a phenomenon. Henry's Law states that every compound has a certain affinity to exist in a particular physical state: solid, liquid, or gas. The physical state in which each compound exists is predicated on temperature, pressure, and its desire to be in that state. Volatility is a function of these three components. For compounds present in aerosol cans, Henry's Law dictates that only a particular volume of the compound may exist in the gaseous state while the remainder will exist in the liquid state. Once this equilibrium is established it can not be disturbed until either the liquid or gaseous fraction is displaced.

With regard to this Field Test, it may be that within the emptier cans the compounds exist in different equilibrium proportions. Emptier cans may contain a greater proportion of propellant in the gaseous state. Upon discharge the collection receptacle will therefore receive a large volume of gaseous material. The equilibrium will continue to facilitate propellants being pushed to the carbon bed as well as propellants volatilizing from the liquid state to the collection drum headspace. Simultaneously, desorption of propellants in the form of propane, butane, isobutane, and dimethyl ether from the carbon bed occurs.

Coconut carbon has a very low affinity for these propellants, 0.3% by weight. As such, excessive propellant loading would facilitate desorption. Excessive propellant loading was observed during the Field Test when multiple full cans were processed. Target analyte (compounds for which coconut carbon has a higher affinity) introduction also facilitates propellant displacement and subsequent desorption. Target analytes were introduced in appreciable concentrations when full cans were processed during Test Runs #1, #4, #5, #6, and #7. Test Runs #6, and #7 were primarily target analytes (perchloroethylene) and adsorbed nearly 100% onto the carbon. Test Runs #4 and #5 were a combination of target analytes (chlorofluorocarbons) and less volatile compounds with a high affinity for coconut carbon. The carbon filter beds associated with these Test Runs adsorbed the target VOCs quite well. However, as concentrations of the less volatile compounds became significant, desorption occurred. Test Run #1, Eco-Sure paint, was comprised primarily of LPG propellant and minimal concentrations of target analytes. The processing of several full cans of Eco-Sure paint equated to larger volumes of the target analytes being processed through the carbon filter beds. Monitoring results indicate that as target analytes adsorbed onto the beds they displaced the LPGs.

Analytical results from collection drum sampling and air samples drawn from the liquid drum sample port have demonstrated that target compounds are present in appreciable amounts. However, exhaust emissions analytical results indicate that target compounds are not desorbing nor escaping from the carbon filter bed in detectable concentrations. Therefore, the target compounds introduced into the system are being effectively adsorbed and retained by the carbon filter bed. This further supports the conclusion for Objective 3a.

Monitoring results suggest that the desorption phenomenon and coconut carbon affinity work in concert to create a more effective adsorption system for target compounds. The displacement of LPGs frees up more space to adsorb target compounds. As time goes on, LPGs and non-target compounds are continually displaced increasing the effectiveness of the carbon bed filter. Monitoring results indicate that this is not a probability, but a reality.



Objective 3b: Measure the total organic vapor concentrations in carbon filter breakthrough emissions and assess their risks to worker health and safety.

One of the more difficult challenges DTSC, PWC and Aerosolv representatives faced in developing the Field Test Plan was creating a definition for carbon filter saturation. Coconut carbon is considered to be saturated when it is no longer effective in preventing emissions of target compounds in excess of established health and safety thresholds. Various target compounds exhibit varying degrees of toxicological effect. Therefore, it is difficult to establish a single threshold for all compounds. Because there is no readily agreed upon baseline for determining the toxicity of target compounds prevalent in aerosol cans, it was agreed as a compromise to use 90% carbon filter effectiveness (carbon filter breakthrough emissions of 100,000 ppm) as the point at which testing would cease. The 90% carbon filter effectiveness (100,000 ppm) threshold was derived from recommendations published by coconut carbon manufacturers for the specific target compounds present in the aerosol cans being tested. This compromise was agreed to by the Navy and Aerosolv for purposes of the field test only. Appendix I, Section 2, Exhaust TVA Results and Carbon Bed Performance, details the Field Test Plan strategy in collecting this data. Total exhaust emissions were monitored as if they were exclusively target compounds.

With respect to any emissions coming off of the carbon filter, no target compounds were found at laboratory reporting limits; thus the emissions were propellants. Monitoring results support the conclusion that employees were not exposed above OSHA PELs, ACGIH RELs, or NIOSH RELs. Refer to Appendix I, Section 3, Carbon Bed Area Samples, of the Report.


Conclusion

For aerosol paint cans, the carbon filter effectively prevents emission of target compounds at total vapor concentrations of 100,000 ppm. With respect to all of the aerosol cans tested, the carbon filter effectively prevents gaseous emissions from contributing to the employee's overall exposure burden. At no time were employees exposed above OSHA PELs, ACGIH RELs, or NIOSH RELs.



Objective 3c: Assess the adequacy of the established standard operating procedures in determining when the carbon filter needs replacement.

One important objective was to evaluate the effectiveness of the colorimetric indicator on the filter unit. The manufacturer designed the indicator to be sensitive to the target compounds and not to propellant gases. The indicator uses potassium permanganate granules. The standard operating procedure for the Aerosolv® unit recommends changing the filter when the potassium permanganate granules contained within the indicator change color from magenta to black.

As noted in the field logs the colorimetric indicator was monitored during the Test Runs and changes in color were observed. Specifically, the bright magenta granules observed at the commencement of each Test Run were observed to turn dull brown at the conclusion of the run. At no time was any indicator observed to turn black. However, as noted previously, the data collected never indicated that target compounds were ever emitted. Therefore, the carbon filter beds never reached saturation levels. At the 90% carbon filter effectiveness (100,000 ppm) threshold, carbon beds were still effective in capturing target compounds and minimizing worker health and safety concerns (see specifically the Brakleen® Test Runs and the discussion for Objective 3b above).


Conclusion

It is obvious from the data collected that the colorimetric indicators are effective. PWC recommends that additional language in the standard operating procedure clarify that the colorimetric indicator color change is gradual, but saturation is not indicated until it turns black.



Objective 4: Assess Worker Health and Safety in Operating the Aerosolv® Technology

All of the elements described in Objective 4 are discussed in detail in PWC's Industrial Hygienist Workplace Monitoring Report, Appendix I. The Aerosolv® technology in concert with its specified engineering controls effectively prevented adverse worker health and safety exposure during operation. Exposure was maintained well below OSHA PELs. Further, emissions from equipment were recorded 99.96% of the time at less than the LEL action limit, 10,000 ppm. Finally, throughout all seven test runs and under the guidance of six operators, there was never an adverse liquid release such as splashing in eyes or onto dermal surfaces, nor a critical unit failure concern.



Objective 4a: Determine the capability of the Aerosolv® technology to operate such that the vapor/gaseous emissions within the operator's breathing zone do not exceed the allowable daily exposure.

Workplace monitoring results indicated that PWC employees were not exposed to vapor/gaseous emissions within the operator's breathing zone above established PELs as enforced by OSHA. Breathing zone exposure results are contained in Appendix I, Section 3 of the Report.



Objective 4b: Determine the capability of the Aerosolv® technology to operate such that the vapor/gaseous emissions within the operator's breathing zone do not exceed other regulatory limits.

Additional workplace monitoring results indicated that PWC employees were not exposed to vapor/gaseous emissions within the operator's breathing zone in excess of other occupational exposure limits recommended by NIOSH and ACGIH. Breathing zone exposure results are contained in Appendix I, Section 3 of the Report.



Objective 4c: Determine the potential for emissions from operation of the Aerosolv® technology to exceed 10% of the LEL.

Workplace monitoring results indicated that 99.96% of the total data points collected were less than the lower explosion action limit (LEL) of 1% (10,000 ppm). LEL monitoring results are contained in Appendix I of the Report.



Objective 4d: Determine the effectiveness of the technology in preventing releases of the liquid contents of the aerosol cans.

During the preliminary test run (Break-In Run) respirators, safety glasses, and gloves were utilized. During this preliminary test the process was evaluated to determine appropriate levels of personal protective equipment required for the remainder of the Test Runs. While protective safety glasses and gloves were maintained throughout the balance of the Test Runs, the emissions data indicated it was unnecessary to maintain the respirator throughout the tests. While safety glasses and gloves were utilized, no significant splashing or spraying was observed. A total of 2,267 cans were processed in a total of 4,130 minutes.


Conclusion

The Aerosolv® technology has successfully demonstrated that its operation does not adversely affect worker health and safety. In fact, the technology effectively minimizes employee exposure to target compounds in the operator's breathing zone; safely reduces the threat of fire or explosion; and facilitates proper collection of hazardous materials.

IV. CONCLUSION OF THE FIELD TEST DEMONSTATION


The Aerosolv® technology has successfully demonstrated that it is a safe and effective aerosol can recycling technology. Worker health and safety is not compromised. The risk of injury or explosion is minimized. Pollution prevention objectives such as recycling and land disposal diversion are greatly enhanced. Technology expense and logistical concerns are minimal. And the technology is easy to operate and maintain.



Regulatory Status of Aerosol Cans: A Navy Perspective

Aerosol can management and disposition has long been a hazardous waste concern because aerosol cans present unique challenges with regards to hazardous waste regulations. First, there's the question of whether or not an inert container holding hazardous waste can actually contribute to the hazard presented by the waste. Aerosol cans are usually filled with compressed liquefied gas and liquid product. The gas may be ignitable, halogenated, or inert. The product may contain suspended colloidal solids and exhibit the hazardous waste characteristics of ignitability, corrosivity, or reactivity. When this combination of potential hazards is placed in a container, a potentially hazardous environment under pressure is created.

It has been argued that the environment created in the aerosol can is similar to that created in compressed gas cylinders. Therefore, aerosol cans are truly a form of compressed gas cylinder and it is reasonable to assume that regulations regarding aerosol can management would parallel those pertaining to compressed gas cylinders. In fact, until recently, the Department of Transportation, Research and Special Programs Administration (RSPA) classified aerosol cans as compressed gas cylinders. Today, RSPA classifies both as flammable or non-flammable gases. Neither is classified as an explosive of any consequence. This is because compressed gas cylinder carcasses (and aerosol can carcasses) are not deemed to contribute to the hazard presented by their contents (they are not viewed as reactive hazardous waste). The EPA and most states in the U.S. have adopted this interpretation.

Conversely, the State of California argues that aerosol cans are reactive because they are sealed containers that prevent the escape of material under pressure. When heated, the pressure inside the can increases until the can fails. Upon failure, the contents of the can are released suddenly and the can is propelled violently. The Department of Toxic Substances Control (DTSC) further argues compressed gas cylinders and aerosol cans are uniquely different (though there's never been a formal explanation as to why). Therefore, although compressed gas cylinders are not viewed as reactive hazardous wastes, aerosol cans are viewed by DTSC as being reactive. Opponents of California's stringent interpretation claim that, based upon the DTSC interpretation of reactivity (described above) an aerosol can is no different than a can of solvent-based paint or a 55-gallon drum of gasoline. All have the potential of creating an enormous amount of internal pressure and consequently creating a potential projectile hazard. However, paint cans and drums of gasoline aren't regulated as reactive hazardous wastes. California argues that the aerosol can itself contributes to the hazard presented in a uniquely different manner than a can of paint or a 55-gallon drum of gasoline and therefore merits the reactive designation.