Air Compliance

Leadership in Air Compliance: Tackling Hazardous Air Pollutants with a Novel Biofilter

Learn how Wood Products industry leader, Arauco, tackled air compliance and emission limits using a biofilter for a Medium-density fibreboard (MDF) Dryer Exhaust.

Environmental compliance sometimes means following a permit’s conditions or doing an inspection, but where the challenge often lies is when you are problem solving!

We talked with one of the Wood Products Industry leaders, John Bird of Arauco about the iterations, challenges, and successes of using a biofilter for air compliance in our latest webinar. Typically thermal oxidizers or a chemical scrubber might be used to reduce Hazardous Air Pollutants (HAPs) to meet air permit standards. However, Arauco and John Bird, their Corporate Environmental Manager, got creative in their approach to meeting permit requirements with their thermophilic biofilter to treat dryer exhaust from their Medium-density fibreboard (MDF) facility. 

Originally they had a chemical scrubber at their MDF facility, but due to concerns using hydrogen peroxide, including potential spills or accidents when transporting and delivering it, they wanted a different system. The state of North Carolina encouraged them to look beyond the typical systems, such as thermal oxidizers, to non-incineration technology to address the methanol and formaldehyde in their exhaust. This led them to look at biofilters where they considered towers of bioscrubbers with large wastewater discharges to treat plants and systems requiring significant air mixing to balance their exhaust.

They ultimately settled on a thermophilic biofilter that used bacteria that preferentially consumed formaldehyde, removing 100% of it from the exhaust. However, their system was not without challenges.

As John shared on our Coffee & Compliance webinar, one challenge was that their thermophilic bacteria were great at consuming formaldehyde, but not so great at methanol reduction. In reality you can address one but not the other without either different treatment tanks in a treatment train or significant increases in retention time. For John’s system with a 15 second retention time, the footprint might be increased by four times, which negates some of the positives in selecting this biofilter.

The other major challenge was the construction of the concrete tank to hold the biofilter as the influent air and water contained weak acids. Over time the concrete was eaten away resulting in a major repair project. They had used their typical contractor that was good at facility maintenance but this was the first time they were constructing holding tanks and ultimately an acidic resistant liner was needed as part of the repairs.

See the complete discussion for a full wastewater and air system geek out. It was fascinating to hear how a novel approach to air compliance involves tricky wastewater treatment processes.

Key Takeaways:

  • A new approach to air compliance means going beyond scrubbers and thermal oxidizers

  • Conduct pilot testing before full-scale launch for novel systems

  • Sample the full range of parameters in a waste stream, not just the regulated pollutants

  • Select a contractor familiar with the specific system components and their application, not just a general maintenance contractor

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To hear more from environmental leaders, check out our upcoming Coffee and Compliance webinars here.

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