Air Pollution Control Innovations

Achieving Ultra-low Emission Limits for Medical Waste Incinerator Scrubbers

Posted by Andy Bartocci on Wed, May 16, 2018 @ 08:00 AM

Last March I gave a paper and presentation at the International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC) in Houston, TX.  The paper discusses the challenges for meeting ultra-low emission limits for medical waste incinerators. 1102_UTMB_Scrubber_Skid Wet scrubbers are used to control hazardous air pollutants (HAPs) on many hospital, medical, and infectious waste incinerators (HMIWI).   The Maximum Available Control Technology (MACT) standard for these incinerators was revised and became final in 2009.  The new standard has the lowest emission limits for incinerators today. The limits exceeded the capability of systems designed to the previous standard with respect to particulate matter (PM), lead (Pd), cadmium (Cd), mercury (Hg), and dioxin/furans (D/F).  By 2014 all existing medical waste incinerators were either shut down or upgraded to comply with the new standard.  Envitech successfully upgraded four existing medical waste incinerators.  A paper presented at the 2012 IT3/HWC conference describes one of these systems which was installed at the National Institute of Health (NIH), Rocky Mountain Labs.

The challenge moving fo1102_General_Assembly_1rward will be new medical waste incinerators which have even more stringent, ultra-low emission limits.  Building a new incinerator requires critical decisions on control technologies and permitting.  The IT3/HWC paper reviews these issues for specific HAPs and discuss trade-offs between permitting a new medium size incinerator versus a large incinerator.   An example is provided of an air pollution control system meeting the emission requirements for a new large medical waste incinerator at the University of Texas Medical Branch (UTMB) in Galveston, TX.  Envitech is also building gas cleaning systems for two new medium size medical waste incinerators for a research facility which integrate NOx control using ozone injection.

 

Please click on the links below download the presentation and paper.

 Download Literature

Topics: Scrubbers, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Carbon Bed Adsorber and Filter Used to Remove Lead (Pb), Dioxin, Furans, and Mercury (Hg) to Meet New Medical Waste Incinerator Emission Limits

Posted by Andy Bartocci on Thu, Apr 14, 2016 @ 08:30 PM

WMC.jpgIn 2009, the US EPA revised the emission limits for the Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT standard. You can follow the link to the blog piece published in May 2013 on the new standard. It dramatically reduced the emission limits for several pollutants including particulate (PM), lead (Pb), and dioxins and furans (D/F). Several existing medical waste incinerators in operation at the time were not capable of meeting the new limits, especially for lead (Pb) and/or dioxin and furans (D/F). Cost effective add-on controls were needed to bring existing system into compliance with the new rules and to allow them to continue to operate.

 

To meet this new challenge, Envitech designed a carbon bed adsorber and filter package to be installed downstream of existing wet scrubbers. The package is comprised of a new fan to overcome additional system pressure drop. Heat of compression from the fan and a re-heater duct heats the wet gas above the dew point to prevent condensation fouling in downstream filter and/or carbon bed adsorber. The system is delivered pre-assembled on a skid to reduce installation time and cost. A cartridge filter removes low concentrations of condensed Pb particulate. The carbon bed adsorber removes dioxins, furans and mercury (Hg). Envitech has upgraded four medical waste incinerators to meet the new MACT standards. All four are operational and compliant with the new standards.

In one case for Wyoming Medical Center (WMC), space was limited for add-on controls. The system had to be installed outdoors and capable of withstanding below freezing temperatures. The existing system did not meet the new limits for lead (Pb) and dioxins/furnace (D/F).The add-on controls included a cartridge filter and a carbon bed adsorber. The equipment was insulated and heat traced to maintain temperature above the dew point after re-heat. System features include:

  •  Shop and skid mounted assembly for ease of installation.
  • Insulation and heat tracing for outdoor operation in a cold climate.
  • Silicon controlled rectifier (SCR) controller to control the heater duct.
  • Compressed air pulse cleaning for automatic particulate removal from the cartridge filters.
  • Pre-wired instrumentation to a control box located on the skid.
  • Manways to facilitate maintenance access.

The system has been operational since 2014 and has been used on a routine basis during cold winter months.   The system comfortably passed a stack test in 2015. Compliance for lead (Pd) is 20 times below the limit and Dioxins/Furans (D/F) is 5 times below the limit. The re-heat and filter package has been used on several other medical waste incinerators and provide a cost effective solution for meeting stringent emission limits. 

Download a free case study to find out how Wymoming Medical Center met the new EPA HMIWI emission limits for their existing medical waste incinerator.

Download  Case Study

Download a free white paper from the 2010 Internationa Conference on Thermal Treatment Technologies and Hazardous Waste Combustors (IT3/HWC) on the 2009 HMIWI MACT standard for medicl waste incinerators.

Download Free Paper 

Topics: particulate control, Venturi scrubbers, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Meeting the HMIWI MACT Standards Ultra Low Lead (Pb) Emission Limit for a New Medical Waste Incinerator Scrubber System

Posted by Andy Bartocci on Wed, Feb 17, 2016 @ 04:28 PM

In October 2014, existing medical waste incinerators had to be compliant with the US EPA’s new Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT standards. Nearly all of the systems that planned to continue incineratrion had to be upgraded with add-on controls to meet particulate (PM), lead (Pb), mercury (Hg), Cadmium (Cd), dioxins/furans (D/F), or a combination of the pollutants. Pb was the most common of those pollutants requiring additional capture.

Envitech upgraded scrubbers for three existing medical waste incinerators. In October 2015, I presented a 1102_General_Assembly_1.jpgpaper at the International Conference of Thermal Treatment 1102_General_Assembly_1.jpgTechnologies and Hazardous Waste Combustors (IT3/HWC) about using a wet electrostatic precipitator (WESP) on the National Institute of Health’s (NIH’s) Rocky Mountain Lab (RML) existing medical waste incinerator. Envitech also designed and built a fourth scrubber system which was permitted as a large (> 500 llb/hr of waste) new medical waste incinerator. The table below compares the previous 1997 standard for lead (Pb) for a large incinerator to the current (2009) standard for an existing incinerator and a new incinerator.

As shown, the current emission limit for an existing incinerator is just 3% of the limit for the 1997 standard. Add-on controls need to achieve 97% reduction in Pb for medical waste incinerators just meeting the previous limit. This is a significant reduction.

Lead (Pb) Emission Limits for Large Incinerators, mg/dscm

  • 1997 standard                   1.2
  • 2009 standard existing       0.036
  • 2009 standard new            0.00069

1102_UTMB_Scrubber_Skid.jpgPb reduction for a new large medical waste incinerator is even more dramatic. The emission limit is a mere 0.06% of the 1997 standard. Compared to an existing system permitted to the new standard, a large new medical waste incinerator must emit 2 orders of magnitude less Pb.

Envitech’s scrubber for a permitted new medical waste incinerator recently passed the stack test and demonstrated compliance with Pb emission less than 0.00069 mg/dscm. We believe it’s the only systems in operation today that is compliant with the HMIWI MACT standard for a large, new medical waste incinerator.

It is interesting that despite the ultra low emission standards required by the HMIWI MACT standard, there is still significant public resistance to new permitted systems. It’s clear the public doesn’t understand the impact of these rules and how far technology has come to enable environmentally friendly and safe operation of these systems. The role of these captive systems (treating waste from the facility where it is generated) may become more important in emergency response plans of state and local governments. This was evident during the recent Ebola episode where large amounts of waste needed to be treated and disposed. Some would claim that treating the waste at the facility where it is generated poses less public risk than transporting the waste on public roads and highways to a centralized hazardous waste facility. More work needs to be done to educate the public on the capability of these advanced emission control technologies.

For more information on this topic, please read our paper at the IT3 conference.

Download Free Paper

Topics: Scrubbers, MACT Standards, Ebola Waste, Medical Waste Incinerator Scrubber, HMIWI Scrubber

IT3/HWC 2015 Conference October 20-22, 2015 – Wet Electrostatic Precipitator for Medical Waste Incinerators

Posted by Andy Bartocci on Tue, Sep 22, 2015 @ 01:47 PM

Envitech will attend the International Conference on Thermal Treatment Technologies (IT3/HWC), October 20-22, 2015 at the Crowne Plaza Hotel in downtown, Houston, Texas.  The preliminary technical program can be downloaded from the conference website.   The conference features key note speakers from Veolia, Clean Harbors, Essroc, TCEQ, and B3 Systems.

Envitech will have an exhibit booth and present a paper, “Meeting the New Hospital, Medical, and Infectious Waste Incinerator (HMIWI) MACT with a Wet Electrostatic Precipitator (WESP)”.  The paper will provide an overview of a new medical waste incinerator scrubber system with a wet electrostatic precipitator to treat the off gas from two existing medical waste incinerators. The new system was required to achieve a 20% reduction in particulate (PM) emissions, and a 93% reduction in lead (Pb) emissions from the previous gas cleaning system.  The new system has been operational since October 2014.  The table below compares the performance of the emission limits to the new compliance standards. The results demonstrate the system comfortably meets the new EPA MACT standards.

 

Pollutant

 

Units

Compliance

Limit

Test Result

% of limit

Particulates, EPA Method 5 gr/dscf 0.020 15%
Pb EPA Method 29 mg/dscm 0.018 6%
Cd, EPA Method 29 mg/dscm 0.013 10%
Hg mg/dscm 0.025 1.0%
Dioxins/furans, EPA Method 23 Total (ng/dscm) 0.85 5%
  TEQ (ng/dscm) 0.020 15%
HCl, EPA Method 26 ppmv 7.7 1.6%
SO2 ppmv 4.2 35%

Click on the icon below to download a copy of the paper.

Free_Paper

Topics: particulate control, Venturi scrubbers, wet electrostatic precipitators, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber

Rectangular Acid Gas Scrubber Lowers Installation Cost and Improves Maintenance

Posted by Andy Bartocci on Thu, Jul 09, 2015 @ 03:29 PM

Acid gas scrubbers are one of the most common types of air pollution control systems found in industry.  They are often used to treat exhaust gases from combustion sources such as incinerators, hazardous waste combustors, thermal oxidizers, regenerative thermal oxidizers (RTO), furnaces, and direct fired heaters.   Acid gas scrubbers are found on a wide range of facilities including, geothermal plants, secondary lead smelters, waste oil re-refiners, refineries, chemical and pharmaceutical plants, and mineral and metal processing facilities.  The most common types of acid gas emissions are HCl and SO2, but can also include Cl2, HBr, HF, and NOx.

Most acid gas scrubbers are wet scrubbers using vertical packed bed absorbers.   In the case of combustion sources, the scrubber is coupled to an evaporative quencher to cool the gas to saturation before it passes to the packed bed. This arrangement is shown in the adjacent figure for a medical waste WSU_Vertical_Scrubberincinerator.  The incinerator exhaust is ducted to a metal quencher (shown in the foreground). The hot gas enters the top of the quencher and flows vertically downward. The gas then elbows into the bottom of a vertical packed bed scrubber (shown in the background). The gas passes upward through the packed bed as re-circulated water flows downward, counter-current to the gas from the top of the packed bed.  Water from the quencher and packed bed is collected in the sump and re-circulated back to the quencher and packed bed.  An entrainment separator at the top of the scrubber removes entrained water droplets.  After exiting the scrubber vessel, an interconnect duct transports the gas to a induced draft fan located at grade.

The scrubber above is one of the earliest Envitech medical waste incinerator scrubbers.  These types of scrubbers are often installed in hospitals where critical design considerations include limited space, low ceilings, and difficult to reach locations through elevators and narrow corridors.  To help minimize installation costs Envitech developed a rectangular scrubber which is shown in the figure below. 

UTMB_Scrubber_Skid_Pic

 

 

 

 

 

 

 

 

 

 

 

This configuration provides several advantages over a vertical scrubber, including:

Greater integration and pre-assembly of ancillary equipment and pumps, piping, valves, and fittings.

  • Ground level access manways for safer, easier maintenance.
  • Simplified ductwork connection to the fan and stack.
  • Elimination of caged ladders and platforms for nozzle and mist eliminator access.
  • Ability to fit in locations with low head space.
  • Simplified requirements for setting and integrating equipment which lowers installation costs.

The rectangular scrubber has been used on over 60 installations.  Envitech has found that facilities tend to prefer a rectangular design over a vertical scrubber for the advantages noted above.  In some cases, total installed cost is reduced by 40% to  50%.  Weather a scrubber is purchased from an EPC contractor, upstream equipment supplier, or architectural & engineering firm, it is recommended that facility preferences be taken into consideration in the final selection process.

The video link below shows a few recently installed rectangular scrubbers at waste oil re-refiners as well as several examples of other rectangular scrubber installations.

 

 

Click the link below for a free case study on  a rectangular acid gas scrubber for a direct fired heater at a waste oil re-refiner.

Download Case Study

Click the link below for a free case study on a rectangular medical waste incinerator scrubber for the control of acid gases, particulate, and heavy metals.

Download Case Study

Topics: Scrubbers, SO2 Scrubber, Acid Gas, HMIWI Scrubber

Medical Waste Incinerator Scrubber Used to Process Ebola Waste

Posted by Andy Bartocci on Wed, Nov 05, 2014 @ 08:43 PM

Envitech recently got noticed in a local news story by Michael Chen of Channel 10 News, “Local Company Helps Dispose of Ebola-tainted Waste”.  The story talks about the challenges of processing Ebola waste and how Envitech’s Medical Waste Incinerator Scrubber at the University of Texas Medical Branch (UTMB) was used to dispose of waste generated by an Ebola patient in Texas.

UTMB operates the only permitted medical waste incinerator in the state of Texas.  Since 1991 the facility has operated an incinerator which uses an Envitech wet scrubber system to clean the exhaust gases of harmful pollutants.  A new incinerator system was recently installed to meet the new EPA rules promulgated for the hospital, medical, and infectious waste incinerator (HMIWI) maximum achievable control technology (MACT) standard.  The impact of these rules is discussed in a previous blog post.

The outlet emission requirements of the new standards are a significant reduction from the previous 1997 standards.  The allowable outlet emissions for many of the metals, i.e. lead (Pd), Cadmium (Cd) are less than 1% of the previous emission limits. For example, the allowable concentrations for Pb,and Cd are measured in 10-7 and 10-8 gr/dscf, respectively.  These are some of the lowest HAPs emission limits for industrial sources in the United States. Medical Waste Scrubber Below is a summary performance guarantee for the new scrubber system based on the new HMIWI standard:

  • PM < 18.3 mg/dscm (0.008 gr/dscf)
  • Lead < 0.00069 mg/dscm (3.0 x 10-7 gr/dscf)
  • Cd < 0.00013 mg/dscm (5.7 x 10-8 gr/dscf)
  • HCl < 5.1 ppmv dry
  • SO2 < 8.1 ppmv dry
  • Dioxins/Furans < 0.035 ng/dscm on TEQ basis

Recent episodes of processing highly infectious waste from Ebola patients may re-ignite a policy debate on medical waste disposal. In the early 1990, many hospitals were going to a model of owning and operating a relatively small medical waste incinerator to process and destroy medical waste generated in-house. These systems typically have a capacity of 500 to 1,500 lb/hr. As air emission standards became stricter, many hospitals decided to shut down their incinerators and ship their waste to larger, centralized medical waste incinerators. These systems are much larger in capacity. For example, the largest medical waste incinerator facility is in Baltimore, MD with a permitted capacity of 150 ton/hr. The trade-off of a centralized waste incinerator is the risk and liability of transporting the waste on public roads and highways. The recent Ebola outbreaks bring to light that some of this waste can be highly infectious and pose a significantly greater risk to public health. It also came to light that a single Ebola patient generates a substantial amount of infectious waste. In this scenario, it may make more sense for facilities to have the capacity to destroy their own waste and avoid the risk of transporting it over great distances on public roads.

The advancement of scrubber technology and compliance with the new, more stringent EPA MACT standards, confirm the ability to operate medical waste incinerators with virtually no harmful emissions into the air.  In addition to the UTMB medical waste scrubber system, Envitech has upgraded several other medical waste incinerators for meeting the new standards.  Based on the extreme low emission limits, the results are truly groundbreaking and may encourage states and facilities to permit new systems.

For more information on HMIWI regulations, please read our white paper.

Download Free Paper

Topics: Venturi scrubbers, MACT Standards, Ebola Waste, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber