Air Pollution Control Innovations

Medical Waste Incinerator Scrubber MACT Standard Compliance

Posted by Andy Bartocci on Wed, Sep 01, 2021 @ 07:50 AM

Medical waste scrubber DHSThere are several different waste incinerator source categories controlled by EPA standards under the Clean Air Act (CAA). These include hazardous waste combustors (HWC), sewage sludge incinerators (SSI), municipal solid waste (MSW) incinerators, commercial and industrial solid waste (CISWI) incinerators, and Hospital, Medical, and Infectious Waste Incinerators (HMIWI). Each incinerator type has its own Maximum Achievable Control Technology (MACT) standard which establishes technology based limits for emitted HAPs. MACT standards are part of the National Emission Standards for 

Medical Waste Venturi DHS

Hazardous Air Pollutants (NESHAP) and are applied to source categories that pose adverse risk to human health by the emission of hazardous air pollutants (HAPs).  The HMIWI MACT standard for medical waste incinerators is the most challenging of the incinerator source categories. This standard controls particulate (PM), hydrogen chloride (HCl), sulfur dioxide (SO2), lead (Pb), cadmium (Cd), mercury (Hg), dioxins/furans (D/F), nitrous oxide (NOx), and carbon monoxide (CO). Emission limits depend on the incinerator size and weather it is a new or existing source. Small incinerators are less than 200 lb/hr of waste throughput, medium incinerators are between 200 lb/hr and 500 lb/hr, and large incinerators are greater than 500 lb/hr.

Envitech recently completed a project for two medical waste incinerators at a Midwest research facility. These are the first new medical waste incinerators installed in the United States since Envitech installed a 525 lb/hr medical waste incinerator at a research facility in Galveston, TX in 2013.

The scope of supply includes two medical waste incinerator scrubbers and a water treatment system to treat the blowdown from both incinerators. The incinerators are permitted as new, medium size incinerators. Ozone injection is integrated into the system to meet a NOx limit of 67 ppmv. The systems include pre-assembled pumps, piping, valves, and fittings to minimize installation time and cost. The pre-assembly provides long term rigidity, consolidation of space, longer up-time, and improved safety for operators. A description of the process arrangement can be found in this link to an earlier blog post.

Stack testing was performed in June 2021 for both incinerators. Test results confirm the Envitech system reduced emissions well below MACT standard limits, providing a comfortable margin for compliance over the range of operating conditions and waste feed. Below is a summary of stack test performance.

Parameter Emission Limit Result, %Limit
PM < 0.0095 gr/dscf 17.9
Pb < 0.018 mg/dscfm 8.9
Cd < 0.0098 mg/dscfm 4.6
Hg < 0.0035 mg/dscfm 25.7
D/F < 0.014 ng/dscm TEQ < 1
HCl < 7.7 ppmv dry < 1
SO2 < 1.4 ppmv < 1
NOx < 67 ppmv dry 24

Click on the link below to download literature on medical waste incinerator scrubbers.

Download Literature

Topics: Scrubbers, MACT Standards, Medical Waste Incinerator Scrubber, Incinerator Scrubber, HMIWI Scrubber, Stack Testing, Packed Bed Absorbers, Packed Bed Scrubbers, Wet Scrubbers

Three Things to Do Before a Stack Compliance Test

Posted by Andy Olds on Mon, Nov 02, 2015 @ 05:00 AM

Compliance testing often brings anxiety to environmental managers.  Testing is expensive and can comprise a significant fraction of the environmental operating budget.  Planning takes several months, often culminating in a tight testing window with long days and unforeseen delays.  And always looming is a dreaded phone call of a failed test.  What three things should environmental managers do to ensure a successful compliance test?


  1. Calibrate your control instruments

Manufacturers use complex instruments to ensure that their equipment meets its performance objectives.  These instruments must remain calibrated for the control equipment to perform properly. pH sensors, ORP probes, flow transmitters and conductivity sensors ensure optimal acid gas removal.  RTDs and thermocouples are vital to reliable operation for thermal oxidizers, condensers and reheaters.  Pressure transmitters provide important information for the performance of Venturis, and the condition of baghouse, carbon beds and packed beds.

The most common deficiency reported in our service call database is an out-of-calibration instrument.  Make sure that your instruments calibration is up to date, and check its performance a month prior to compliance testing to ensure you have the time to order a replacement instrument if required.

  1. Inspect and clean your equipment

Environmental control equipment typically faces an array of upset conditions.  Waste streams change or cycle through daily, weekly or seasonal disruptions.  Auxiliary equipment fails leading to changes in the quality of makeup water, instrument air, or power.  Repeated startups and shutdowns lead to transient states of substandard performance.  The struggle to keep environmental compliance equipment operational at all times leads to an "emergency-only" attitude towards preventive maintenance.  All of these factors lead to degradation of equipment and instruments.

Ahead of compliance testing, it is important to challenge the operations staff to inspect and clean the equipment.  Ensure instruments do not have buildup that dampens response time.  Confirm pressure drops across filters, strainers, spray nozzles are at design conditions; high pressures may be indicative of fouling.  Make sure consumables such as pH probes and filter bags are new and up to date.  Check for air ingress; most compliance tests measure the oxygen content of the gas to ensure that emissions are not artificially lowered by dilution air.  Clean sumps, separators and nozzles during regular shutdowns.  Ensure that your emissions are limited to that which occurs during steady state operation, and not from old emissions that have built up on the internal surfaces of your equipment.

  1. Interview your stack tester

The EPA has well-developed procedures for every type of emission test.  However, with ever lowering standards, stack testers are forced to push their instruments and apparatuses to their technological limit in order to accurately measure emissions.  Stack testers have found ways to extend these limits, but the difference between emissions and noise is narrowing.  Minimizing the noise, and understanding the methodology of the stack test, will ensure you and your equipment are well-prepared.

For all stack tests, ask the following:

  • What EPA procedures will you be using?
  • Are there any known interferences for the procedures?
  • What is the experience level of the stack test operators with each procedure?
  • Are you prepared for lower than expected gas flow rates, greater than expected dilution, or other flue gas variances?

For initial testing:

  • What is your expectation of the non-detectable limit with the procedure provided?
  • Is the expected non-detectable limit sufficiently low to provide accuracy below my emission limit?
  • How do you intend to reliably rig and stabilize your instruments?
  • What can I do to give the stack testers the best opportunity to provide reliable data?

If your permit has changed since your last stack compliance test:

  • Have you accounted for my new permit requirements, and how has that changed your testing protocol?

Getting ready to perform a stack compliance test?  Contact Envitech Service for a site visit to calibrate your instruments and inspect your equipment.

Contact Envitech Service

Topics: Stack Testing