Efficacy of photocatalytic HEPA filter on microorganism removal.

[Guest guest]

Efficacy of photocatalytic HEPA filter on microorganism

removal.

Chuaybamroong P, Chotigawin R, Supothina S, Sribenjalux P, Larpkiattaworn

S, Wu CY.

Indoor Air. 2010 Jun;20(3):246- 54.

Department of Environmental Science,

Faculty of Science and Technology, Thammasat University, Thailand.

Abstract

This study assessed the application of photocatalytic oxidation (PCO) to

the high efficiency particulate air (HEPA) filter for disinfection of airborne

microorganisms. Experiments were conducted at two TiO(2) loadings (1870 +/- 169

and 3140 +/- 67 mg/m(2)) on the HEPA filter irradiated with UV-A at the

intensity of 0.85 +/- 0.18 or 4.85 +/- 0.09 mW/cm(2) under two relative humidity

conditions (45 +/- 5% and 75 +/- 5%). Inactivation and penetration of four

microorganisms were tested, including Aspergillus niger, Penicillium citrinum,

Staphylococcus epidermidis, and Bacillus subtilis. It was found that

microorganisms retained on a photocatalytic filter were inactivated around

60-80% and even 100% for S. epidermidis when the PCO reactions occurred. Lower

penetration was also found from the photocatalytic filter for all airborne

microorganisms. High humidity decreased photocatalysis efficacy. Increasing

TiO(2) loading or irradiance intensity did not substantially affect its

disinfection capability.

 

Practical Implications

The high efficiency particulate air filter is used widely to remove

particulates and microorganisms from the air stream. However, the filter may

become a source of microbes if those retained microorganisms proliferate and

re-entrain back into the filtered air. This study demonstrates that such a

problem can be handled effectively by using photocatalytic reactions to

inactivate those confined microorganisms. A 60-100% microbe reduction can be

achieved for a wide variety of microorganisms to provide better indoor air

quality for hospitals, offices, and domestic applications.

PMID: 20573124 [PubMed - in process]

[Guest guest]

a,

An interesting find but not something that will be of help to anyone

with mold sensitivities.

A HEPA filter traps nearly all the particles and there is no real need

to kill them. Most die off in the dry air flow anyway. And the

conditions for microbial amplification are rarely if ever present on

the HEPA filter anyway. So there is no need to kill anything.

Photocatalytic oxidation (PCO, using UV and titanium dioxide) of VOCs

has been around for a while and there are even a few companies selling

consumer versions of the technology.

The original concept is very effective (high UV irradiation, low air

flows, lots of irradiated surface area) but unfortunately, the

consumer versions have low irradiation intensities, small areas of

irradiation and high air flows so the application of the technology is

virtually useless.

The one installation of this technology I observed (in a central

furnace application) was the size of a large light bulb and did

nothing but make the entire office smell of ozone.

So save your money for cleaning and don't spend on PCO, whatever the

literature says.

Jeff

May Indoor Air Investigations LLC

Tyngsborough, MA

www.mayindoorair.com

978-649-1055

> EFFICACY OF PHOTOCATALYTIC HEPA FILTER ON MICROORGANISM REMOVAL.

>

>

> POSTED BY: \ " KRISTINA TOWNSEND\ " KMTOWN2003@...

> KMTOWN2003

>

> Sat Jun 26, 2010 7:15 pm (PDT)

>

> Efficacy of photocatalytic HEPA filter on microorganism

> removal.

>

> Chuaybamroong P, Chotigawin R, Supothina S, Sribenjalux P,

> Larpkiattaworn

> S, Wu CY.

> Indoor Air. 2010 Jun;20(3):246- 54.

> Department of Environmental Science,

> Faculty of Science and Technology, Thammasat University, Thailand.

>

> Abstract

>

> This study assessed the application of photocatalytic oxidation (PCO)

> to

> the high efficiency particulate air (HEPA) filter for disinfection of

> airborne

> microorganisms. Experiments were conducted at two TiO(2) loadings

> (1870 +/- 169

> and 3140 +/- 67 mg/m(2)) on the HEPA filter irradiated with UV-A at

> the

> intensity of 0.85 +/- 0.18 or 4.85 +/- 0.09 mW/cm(2) under two

> relative humidity

> conditions (45 +/- 5% and 75 +/- 5%). Inactivation and penetration of

> four

> microorganisms were tested, including Aspergillus niger, Penicillium

> citrinum,

> Staphylococcus epidermidis, and Bacillus subtilis. It was found that

> microorganisms retained on a photocatalytic filter were inactivated

> around

> 60-80% and even 100% for S. epidermidis when the PCO reactions

> occurred. Lower

> penetration was also found from the photocatalytic filter for all

> airborne

> microorganisms. High humidity decreased photocatalysis efficacy.

> Increasing

> TiO(2) loading or irradiance intensity did not substantially affect

> its

> disinfection capability.

>  

> Practical Implications

> The high efficiency particulate air filter is used widely to remove

> particulates and microorganisms from the air stream. However, the

> filter may

> become a source of microbes if those retained microorganisms

> proliferate and

> re-entrain back into the filtered air. This study demonstrates that

> such a

> problem can be handled effectively by using photocatalytic reactions

> to

> inactivate those confined microorganisms. A 60-100% microbe reduction

> can be

> achieved for a wide variety of microorganisms to provide better

> indoor air

> quality for hospitals, offices, and domestic applications.

>

> PMID: 20573124 [PubMed - in process]

>

[Guest guest]

thanks Jeff,

the only reason i posted it because it was interesting. I'm sure if I dig deep

enough its someebody alighned with some sort of airpurifier company.  Gray beat

it in to my head about a hepa is not enough. 

 I am very happy with my Austin

Thank you again for taking the time to explain that paper.  I'm sure it helped

someone on the group

Cheers

From: jeff@... <jeff@...>

Subject: [] Re: EFFICACY OF PHOTOCATALYTIC HEPA FILTER ON

MICROORGANISM REMOVAL.

Date: Sunday, June 27, 2010, 5:43 AM

a,

An interesting find but not something that will be of help to anyone

with mold sensitivities.

A HEPA filter traps nearly all the particles and there is no real need

to kill them. Most die off in the dry air flow anyway. And the

conditions for microbial amplification are rarely if ever present on

the HEPA filter anyway. So there is no need to kill anything.

Photocatalytic oxidation (PCO, using UV and titanium dioxide) of VOCs

has been around for a while and there are even a few companies selling

consumer versions of the technology.

The original concept is very effective (high UV irradiation, low air

flows, lots of irradiated surface area) but unfortunately, the

consumer versions have low irradiation intensities, small areas of

irradiation and high air flows so the application of the technology is

virtually useless.

The one installation of this technology I observed (in a central

furnace application) was the size of a large light bulb and did

nothing but make the entire office smell of ozone.

So save your money for cleaning and don't spend on PCO, whatever the

literature says.

Jeff

May Indoor Air Investigations LLC

Tyngsborough, MA

www.mayindoorair.com

978-649-1055