che_october-2024 - 5

Chementator
Edited by: Dorothy Lozowski
Comprehensive destruction of airborne contaminants in a
compact bioreactor
T
here are many categories of air contaminants
that may be encountered in industry, from volatile
organic compounds to aerosols to viruses, as
well as a range of particulate matter and ultra-fine
particles, which also vary greatly in size and properties.
This makes it difficult for a single air-cleaning technology
to comprehensively handle such contaminant mixtures.
The air-cleaning technology developed by BioOx (East
Hanover, N.J.; www.bioox.us) claims to capture and destroy
a wide array of airborne contaminants using a novel
bioreactor system.
" Usually, competing systems absorb, but do not destroy,
the contaminant. For example, activated carbon
will adsorb hydrocarbons, but then you still must regenerate
and recover the hydrocarbons for destruction
before re-using the carbon. BioOx can oxidize hydrocarbons
to CO2 and H2O biologically. This means no
regeneration is required, " says Sam Sofer, president and
founder of BioOx. Within the BioOx reactor, enzymatic
media are immobilized on a specialized spiral-biosupport
membrane (see diagram). Water is pumped up from
the bottom of the reactor, where it flows down the membrane,
keeping the media moist. Water is distributed
evenly from above the biosupport, exposing contaminants
to the enzymes, which are activated to begin biooxidation
upon water contact. " A fan at the top of the
reactor promotes convection, creating a clean air dome.
As water flows into the tank, it captures contaminants
via Bernoulli's Principle in tiny bubbles. Once the air pollutants
are captured, brought into the unit and digested
by the media, the clean air dome expands to cover a
larger and larger area, " says Sofer. The special spiral
design of the bio-support membrane supports contaminant
contact with the enzymes due to the turbulence
BioOx
created by cyclone action.
Sofer says that the BioOx system is especially wellsuited
for manufacturing areas where quality control is
key as product batches change and invisible air contaminants
may remain, such as in the production of
paint or flavor ingredients. " For example, if you're making
red paint, and now you want to make white paint,
and there are invisible red paint particles in the air, the
quality control will suffer. " The BioOx reactor has been
demonstrated in a variety of facilities with up to 200 lb/d
contaminant destruction.
Recycling mixed medical waste with steam cracking
C
urrently, medical waste streams are complicated
to recycle because these single-use
products - such as facemasks, syringes, nitrile
gloves and non-woven gowns - consist of
multiple materials and must be considered contaminated
with potentially infectious particles. Now, researchers at
Chalmers University of Technology (Göteburg, Sweden;
www.chalmers.se) have made progress toward a viable
method for recycling mixed medical waste using thermochemical
recycling.
In a study published recently in Resources, Conservation
and Recycling, the Chalmers team showed that a
steam-cracking process could be effective for breaking
apart mixed streams of medical waste into its chemical
building blocks. Depending on the types of waste and
proportions, recycled medical products can yield mixtures
of light olefins, ethane, BTX (benzene, toluene, xylenes)
and other molecules that could then become feed material
for the petrochemical industry to make new plastics.
The team designed a bubbling fluidized-bed reactor
that could handle solid material, and heated the material
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to 700-800°C to initiate a reaction similar to the steam
cracking of naphtha. In the reactor, the waste materials
are broken into small molecules and microorganisms
are destroyed. Through a series of tests, the researchers
processed mixtures that approximate hospital waste,
containing 10 different plastic types, as well as cellulose.
The hospital waste was tested at different temperatures
(700, 750 and 800°C) in a laboratory-scale reactor.
" A significant portion of the carbon in the feedstock could
be effectively recovered as valuable chemical building
blocks . . . enabling their direct application in the chemical
industry and reducing reliance on fossil resources, "
the researchers write. " At 700°C, carbon recovery percentages
were approximately 79% for face masks, 82%
for plastic syringes, 38% for nitrile gloves, and 76% for
non-woven gowns, they found.
The Chalmers scientists are currently developing the
recycling technology based on an in-house industrialscale
fluidized-bed steam cracker with a capacity of 100
kg/h for various plastic-rich feedstocks together with industrial
partners.
OCTOBER 2024
5
http://www.bioox.us http://www.chalmers.se http://WWW.CHEMENGONLINE.COM
che_october-2024

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