MultiPhase for VOC Control, HAP Abatement

Q. What does the “HAP” acronym mean?

A. Hazardous Air Pollutant. This includes volatile organic compounds (VOC).
In many EPA documents, VOC control is called HAP control or HAP abatement.
Other official documents have substituted “Air Toxics” for HAP control or HAP abatement.

Q. Why is your biotreatment system called “MultiPhase”?

A. Because the technology incorporates both liquid phase and gas phase treatment modalities –
it is a biofilter for treatment of air-phase VOC combined with a bioscrubber for treatment of
water-phase VOC. When any VOC is exposed to a spray of water, part of the VOC goes into
solution and part remains in the air phase, in accordance with Henry’s Law. The MultiPhase
takes advantage of this phenomena to maximize VOC destruction in the most effective manner.

Q. What kinds of VOC will the MultiPhase treat?

A. The MultiPhase treats a wide spectrum of VOCs with high efficiency: formaldehyde,
methanol, styrene, xylenes, PAHs,sulfur compounds, glycols, ethanol, solvents, and
many others. MultiPhase can be engineered to be a comprehensive HAP control,
HAP abatement solution for many common industry challenges.

Q. What happens when there are shut-downs?
What if there is not a steady supply of VOC “food” for the bacteria?

A. The bacteria in the biosystem need energy to stay alive. It is their metabolizing of the
VOC that breaks down the VOC into harmless components. The VOC provides food for the
“bugs.” A superior feature of the MultiPhase is that there is a large reserve of VOC in the
water of the bioscrubber. This water is constantly recirculated and sprayed on the media
and bacteria in the biofilter portion. This keeps the bacteria alive and energetic, even when there
is no new VOC being supplied in the air stream to the system. This unique feature gives the
MultiPhase a period ranging from several days to several weeks before the metabolism of
the system really slows down. Other organic food can also be added into the system
to sustain the metabolism.

In other words, we use the liquid phase digester as a storage device for compounds that
take much longer to biodegrade. Water from the digester sump is continuously sprayed on the
special ceramic media in the air phase section of the MultiPhase that sets above the digester
tank. This provides a continuous food source for bacteria in both air and liquid phases of the
process. As such, it allows the system to thrive even when there is not a continuous food source,
usually for several days depending on the application. If there is a lack of food for longer periods,
the digester sump can be supplied with inexpensive supplementary food.

Your question about the non-steady flow of “food” to the biotreatment bacteria is an important one.
For conventional biofilters, this is a serious limitation and the response you’ve received from other
companies is accurate for their systems. In designing the MultiPhase BioSystem this limitation
was one that we expressly set about to mitigate.

Q. What happens when there is a shut down that lasts for many weeks or months?

A. Eventually the bacteria in the system will die. Then the system must be restarted. Tri-Mer
can provide new bacteria in a freeze-dried form to re-seed the system. The bacteria come in
bags, freeze-dried, that are ripped open and emptied into the MultiPhase tank. It takes three
or four days, depending on the size of the system, for the bacteria to flourish on the media and
in the water and the system to be operational. Usually there is plenty of advanced notice
when a plant has been off-line for weeks or months for the MultiPhase to be ready for
operation. If the interruption in flow is only a few days, see the previous question.

Q. How do you keep the system warm in the winter if it is located in a cold climate?

A. The metabolism of the bacteria slows down as they get cold, but they do not automatically
perish. For adequate removal efficiency for HAP abatement, the system needs to be above 65°F.
Usually the heat from the gas being treated is more than enough to keep the system warm.
The water in the tank, which is recirculated over the media, stores a lot of heat, so short
excursions to lower temperatures are not a problem. For longer excursions in the wintertime,
if there is no exhaust gas flowing, steam is mainly used to maintain the liquid sump temperature
above 65°F.

As long as the exhaust gas is entering the system, there is enough thermal energy to maintain
the temperature of the sump. However, if the system is installed in a cold climate, and there is a
plant shutdown, i.e., no exhaust gas flow, steam is needed to keep the sump temperature above
65°F in order to maintain bioactivity in the sump.

As the temperature decreases, the bacteria in the sump will not die, but will become inactive.
So when the plant starts up again, we don't want the sump to heat up before the bacteria
become active again. To obtain a fast start-up after a shutdown, it's preferrable to maintain
the sump at 65°F during the shutdown in the wintertime.

Q. How do we know that the MultiPhase is working properly?

A. MultiPhase is designed like any other piece of process equipment – a major departure
from older biotreatment approaches. It is instrumented with a variety of sensors including pH,
differential pressure, and air flow, which are tracked by process logic control (PLC.) This
provides very good visibility about the operating trends of the system and allows advanced
notice if any parameters are trending outside the set boundaries. For example, if there
is a slow rise in the pressure across the media, the PLC will automatically increase the
wash-down spray to remove accumulated particulate or biomass.

Q. Is there an instrument that will indicate the health of the
bacterial films directly?

A. Yes, Tri-Mer offers a new instrument, developed at a leading biotreatment
research facility, which directly measures the level of activity of the bacteria.
Please contact us for details.

Q. What if I need greater than 95% removal efficiency?

A. Tri-Mer can design MultiPhase systems for 95% removal of total VOC. This usually
provides sufficient HAP control and HAP abatement to meet requirements. However,
if higher removal efficiency is required, our system can be followed by a carbon absorption
device that increases efficiency to 99%. Carbon systems alone are usually not cost-effective
to operate, other than for very low VOC loading levels and low air volumes. On the other hand,
when a very high percentage of the VOC has been removed by the MultiPhase system, carbon
absorption is feasible as a polishing step. Tri-Mer also supplies carbon absorption systems.
Our experience is that most MACT standards for emissions regulations require 90% removal
of VOC. Of course, the customer knows best what a specific project requires. Most air pollution
control agencies will accept 95% from a biofilter in lieu of 98 – 99% from thermal oxidation
because of the other environmental advantages of a biofilter, such as no NOx production
(from the combustion of natural gas), no additional CO2 production (also from the combustion
of the natural gas), and much lower energy use (an advantage to the environment as well
as the owner.)

Q. What’s the latest on formaldehyde emissions regulations?

A. The ARB evaluated formaldehyde emissions exposure within California and concluded
that a major source of exposure is inhalation of formaldehyde from composite wood products.
The International Agency for Research on Cancer has classified formaldehyde "carcinogenic
to humans" due to greater risk of nasopharyngeal cancer. Formaldehyde emissions were
also classified as a toxic air contaminant in California, with no safe level of exposure.

Q. Is this system effective with formaldehyde?

A. Formaldehyde emissions are readily removed with the MultiPhase bio-oxidation system.

Q. We are concerned about NOx generation.

A. The MultiPhase system does not create NOx by-products, and generates minimal waste.

Q. What are the considerations when there’s some particulate in the gas stream?

A. The presence of particulates is a key factor distinguishing the MultiPhase system from
conventional devices, such as thermal oxidizers.

Experts will tell you that the single biggest problem for regenerative thermal oxidizers is particulate
in the gas stream, which can produce fouling and degradation of the media bed, and cause fires.
Often, the cause of the fire is media bed plugging caused by the accumulation of coarse particles
from mechanical sources. Fine particles, in the form of condensable organic compounds, also cause
problems for thermal oxidizers. If they are chemically inert, they can plug the heat exchange media.
Chemically reactive fine particulate are also prone to plug the media of thermal oxidizers – and they
create another hazard as well, in that they can attack the heat exchange media in the oxidizer.

By contrast, the MultiPhase bio-oxidation system is exceptionally well suited to the
particulate-laden gas streams, even those with heavy particulate loading.

Q. What’s the status of MACT standards as they apply to board makers?

A. The air emissions regulations of the MACT standard, (Table 1B Subpart DDDD of Part 63:
Add-on Control Systems Compliance Options) now apply universally to board manufacturing.
Fortunately, there is now a cost-effective, proven bio-oxidation technology for VOC control
that includes formaldehyde emissions, methanol, turpenes, and other VOC emission types
generated by board plants, also the manufacturing of fiberglass, adhesives, resins and
other materials.

The U.S. Court of Appeals for the District of Columbia invalidated the “low risk” subcategory
provisions of U.S. EPA MACT emissions rules for plywood and other engineered wood product
facilities. The ruling means that mills previously exempted from VOC control limits must now
install VOC control, such as a thermal oxidizer, biofilter or MultiPhase BioSystem.

Q. What about the requirements that pertain to LVL?

A. The MultiPhase VOC control system satisfies the regulations applicable to
engineered lumber, MDF, LVL, PSL, LSL and OSL.

Q. What are other, non-wood applications, for VOC control?

A. Excellent applications for this VOC control technology are fiberglass, adhesives,
resins and other manufacturing and processing facilities with VOC control issues. Included
are ethanol production, pharmaceutical manufacturing, print and ink, biomass-to-energy,
and many other applications.

Q. How does the MultiPhase compare in terms of cost with other
bio-oxidation systems and other devices for VOC control?

A. This HAP control technology is significantly less costly to buy and operate than older
approaches such as thermal oxidizers. Total cost of ownership is lower. It provides high
removal rates on high particulate concentrations and heavy loadings of biological treatment
products, without clogging the media beds. The system has documented lower maintenance
and operating costs than other biological treatment alternatives.

Q. What media does the Tri-Mer HAP abatement system use?

A. MultiPhase uses proprietary ceramic media engineered for surface area and fluid flow,
accelerated biodegradation and low gas-phase pressure drop. The media composition also
allows excessive biomass growth to be automatically washed off during system operation.

Q. How often, on average, does the media need to be replaced?

A. MultiPhase VOC control media is permanent, so replacement is never needed.

Q. How does the cost of this HAP control compare with thermal oxidizers?

A. The MultiPhase is favorable in terms of installation and equipment costs, and does
not involve the ongoing (and unquantifiable) expense of natural gas. There is no additional
production of CO2, the primary greenhouse gas.

Q. Does the system provide VOC control in the liquid phase and gas phase?

A. Yes, highly volatile compounds with low water solubility are treated mainly in the gas phase.
Low volatility compounds that are water soluble are treated primarily in the water phase.
Intermediate compounds are treated in both phases.

Q. We’ve considered biofilters and bio-oxidation.
What’s the downside of traditional biofilters?

A. There are several disadvantages of traditional biofilters for VOC control: clogging of beds
due to biomass growth, inability to accommodate particulate, inability to operate above 110°F,
and inability to treat the full spectrum of VOCs with high and low volatility. The MultiPhase has
overcome these limitations.

Q. Is the MultiPhase able to handle hot sources?

A. Yes, unlike conventional biofilters, MultiPhase BioSystem incorporates several
design features that accommodate a hot inlet source, such as a dryer.

Q. What operational test data is available?

A. Field test and full-scale application results for the MultiPhase VOC control system are
available to qualified inquirers. We can also provide substantial documentation comparing
MultiPhase with older devices such as thermal oxidizers.

Interested in a cost-saving alternative to
thermal oxidizers or biofilters for VOC control?
Tell us about it . . . we can help you with some guidelines.

Download MultiPhase Bio-oxidation system for VOC Control brochure

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Tri-Mer Corporation
1400 Monroe Street
P.O. Box 730
Owosso, MI 48867; USA
Phone: (989) 723-7838
Fax: (989) 723-7844
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