Technical Issues Associated with Treatment of Ebola Virus- Contaminated Waste

Transcription

1 Technical Issues Associated with Treatment of Ebola Virus- Contaminated Waste P. Lemieux and J. Wood US EPA Presentation for Research Priorities to Inform Public Health and Medical Practice for Domestic Ebola Virus Disease: A Workshop Washington, DC November 3, 2014

2 Ebola Virus-Contaminated Waste Management Focus of this presentation Collection Staging/ Packaging Transportation Treatment Storage Transportation Disposal

3 Waste Management: Likely Waste Streams Personal effects/medical waste (likely contaminated) Non-porous materials (e.g., gloves, sharps, syringes, etc) Porous materials (e.g., linens, scrubs, pillows, mattresses, etc particularly resulting from contaminated residential and public spaces) Premises/hospital/vehicle decontamination residues (maybe not be contaminated but may be considered to be RCRA hazardous waste depending on characteristics) Wipes, rags, etc. Aerosol cans (e.g., Lysol) Empty bottles of disinfectants Personnel/pet decontamination residues PPE Wastewater/rinsate Waste generation rate 30-40x normal medical waste ( gal drums per day per patient) Expensive to manage ($ >1000 per barrel) 3

4 Ebola Virus Disease (EBOV) Waste Management Considerations Management of EVD Wastes & Decontamination Waste

5 Difficulty of Inactivation vs. Microorganism Types Thermal treatment is analogous to disinfection. However, no available data exist directly evaluating thermal treatment of Ebola virus. These are the organisms tested These are the organisms of concern In general, if a technology can inactivate spores, it will inactivate viruses. However, even though Ebola virus may be relatively easy to kill compared to other microbes, the substrate matrix material (e.g., porous media) can override that factor.

6 Waste Treatment Options Incineration Hazardous Waste Incinerators Wide range of feed types (boxed, bagged, barrels, liquids) Can accept large items May not be allowed to accept (depends on state) Worker health and safety concerns Medical/Pathological Waste Incinerators Limited range of feed types (boxed, bagged) Large items may not fit Worker health and safety concerns Autoclaving Typically bags fed in roll-off containers May be able to handle large items Operational conditions may need to be enhanced Worker health and safety concerns

7 Incineration High temperature combustion Primary chamber effectively kills microorganisms, releases combustion products and particulate matter (fly ash) into gas-phase, generates bottom ash (sent to landfill after making waste determination) Secondary chamber destroys toxic combustion by-products and any microorganisms in gases from primary chamber, combusts organic content of fly ash, releases acid gases and inorganic content of fly ash to air pollution control devices Air pollution control devices Catch particulate matter and acid gases released from combustion Inhibits formation of dioxins and furans

8 Microorganism Destruction in Incinerators: R&D Description Review of medical waste incinerator field test data Commercial medical waste incinerators tested in early 1990s by EPA Doped with large quantities of Geobacillus stearothermophilus spores Spore survival measured in stack and ash Incineration tests at EPA/RTP in pilot-scale rotary kiln G. stearothermophilus spores embedded in bundles of porous building materials Spore survival vs. time/temperature Effect of burning 10%-bleach-saturated carpet on combustor emissions

9 Microorganism Destruction in Incinerators: Test Results Results from MWI test data review & analysis > 6 Log reduction in most cases < 3 Log reduction in a few cases Primary chamber T and secondary chamber RT were most significant variables Results from pilot-scale spore destruction tests Results from pilot-scale dioxin formation tests I-TEQ (ng/dscm) Blank Carpet/DI Water Carpet/Bleach Condition (ND=0; EMPC=0)

10 Microorganism Destruction in Incinerators: Implications Solid-phase residence times long enough to heat core of waste mass to 350 C will kill all microorganisms bound on solids For microorganisms that get into the gas-phase, maintaining proper primary combustion chamber temperature and secondary combustion chamber residence time will assure destruction Ash not likely to have any microorganisms, but must be characterized to determine disposal pathways Bleach may be commonly used as disinfectant, but burning bleach-soaked materials has the potential to increase dioxin emissions Packaging is important so that heat transfer is not inhibited

11 Autoclaves Cycle = evacuation -> steam pressurization -> hold for cycle time -> venting High temperature (> 250 F) saturated steam for a given cycle time Effectively kills microorganisms Extensive history of use for nonporous materials Treated residuals may go for incineration or may go to landfill (depending on state permit requirements and results of testing)

12 Microorganism Destruction on Porous Materials in Autoclaves: Test Description Tested in 2005 on a 96 ton/day commercial medical waste autoclave Porous items (wallboard, ceiling tiles, carpet, upholstered furniture) TCs and BIs (G. stearothermophilus) embedded in loads Varied time, temperature, packing density Anomalous results during first run led to adding additional variable of multiple cycles

13 Microorganism Destruction on Porous Materials in Autoclaves: Test Results 2x as long autoclave cycle Multiple autoclave cycles

14 Microorganism Destruction on Porous Materials in Autoclaves: Implications A second autoclave cycle is much more effective at assuring steam penetration than one long autoclave cycle Cutting bags prior to autoclaving improves steam penetration, but may have health and safety implications for workers Separating items improves steam penetration, but may have health and safety implications for workers

15 Summary Limited capacity of treatment facilities for Ebola viruscontaining waste Properly operated autoclaves and incinerators can destroy microbiological contaminants Second autoclave cycle has profound effect on steam penetration into porous materials Incinerators should use appropriate conditions to maintain primary chamber temperature and secondary chamber residence time Some of the potential improvements to these technologies may result in health and safety concerns for workers

16 Data Gaps Optimal operating conditions for treating DOT-recommended Ebola virus-containing waste packaging NYSDEC testing planned at commercial autoclaves Testing with clean materials Monitoring to be done Wireless data loggers Thermochemical indicators Biological indicators Real time process instrumentation integral to the autoclaves Packaging to be tested DOT-recommended packaging Other potential packaging configurations Appropriate Ebola virus surrogate for R&D usage Disinfectants, waste, and wastewater interactions Waste, wastewater, and incinerator ash sampling and analysis What to do with feces/urine from patients Waste management worker safety Mobile capacity (incinerators and autoclaves) Innovative treatment options

17 Key References Wood JP, Lemieux PM, Lee CW. Destruction Efficiency of Microbiological Organisms in Medical Waste Incinerators: A Review of Available Data. Proceedings of the International Conference on Incineration and Thermal Treatment Technologies; May 10-14; Phoenix, AZ2004. Wood J, Lemieux P, Betancourt D, Kariher P, Griffin N. Pilot-scale experimental and theoretical investigations into the thermal destruction of a Bacillus anthracis surrogate embedded in building decontamination residue bundles. Environmental Science and Technology. 2008;42(15): Wood J, Lemieux P, Griffin N, Ryan J, Kariher P, Natschke D. Thermal Destruction of Bacillus Anthracis Surrogates in a Pilot-Scale Incinerator. Proceedings of the AWMA Annual Conference and Exhibition; June 20-23; New Orleans, LA2006. Lemieux P, Winterrowd C, Realff M, Mulholland J. A Pilot-Scale Study on the Combustion of Waste Carpet in a Rotary Kiln: Dioxin and Furan Emissions. Proceedings of the Conference on Incineration and Thermal Treatment Technologies; May 9-13; Galveston, TX2005. U.S. EPA. Destruction of Spores on Building Decontamination Residue in a Commercial Autoclave May. Report No.: EPA/600/R-05/081. Lemieux P, Sieber R, Osborne A, Woodard A. Destruction of Spores on Building Decontamination Residue in a Commercial Autoclave. Applied and Environmental Microbiology. 2006;72(12):