[Digestion] Hydrogen sulfide - Biogas (Julio Eli Martinez)

Coleman, Pat (Canada) Pat.Coleman2 at aecom.com
Thu Feb 24 21:07:26 CST 2011


The thinking on the effect of H2S on respiratory functions has changed. 

 

Since the 1970s, the exposure limit for hydrogen sulfide (H2S) was 10
ppm (8-hour TWA - time weighted average) and 15 ppm (STEL - short term
exposure limit).  In 2010, the ACGIH revised the exposure limits for H 2
S to 1 ppm (TWA) and 5 ppm (STEL).  The basis and rationale for the
changes can be found in the 2010 ACGIH Documentation for H2S.

 

The ACGIH has documented the following information relating to the
effects of H 2 S: 

 

1000-2000 ppm

Loss of consciousness and possible death

100 - 1000 ppm

Serious respiratory, central nervous, and cardiovascular system effects

150-200 ppm

Olfactory fatigue

100 ppm

Immediately Dangerous to Life and Health (IDLH) concentration

5-30 ppm

Moderate irritation of the eyes

5-10 ppm

Relatively minor metabolic changes in exercising individuals during
short-term exposures

< 5 ppm

Metabolic changes observed in exercising individuals, but not clinically
significant

5 ppm

Increase in anxiety symptoms (single exposure)

5 ppm

Start of the dose-response curve (short term exposure)

 

 

 

Pat Coleman, PhD PEng 
Pat.F.Coleman at aecom.com 
Manager of Process Technology - Wastewater Treatment

AECOM. 



T: 905.712.7025 Mississauga (leave a message and it will be emailed to
me wherever I am)
T. 905.747.7595 Markham

C. 647.637.2898 
www.aecom.com 

 

 

From: digestion-bounces at lists.bioenergylists.org
[mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Matt
Lorig
Sent: Thursday, February 24, 2011 5:44 PM
To: digestion at lists.bioenergylists.org
Subject: [Digestion] Hydrogen sulfide - Biogas (Julio Eli Martinez)

 

If you are using the gas only for cooking there is not really much need
to scrub the H2S.  Keep in mind that it is very corrosive so use plastic
pipes,etc.  

H2S can actually be helpful in low tech applications as the smell lets
you know if you have leaks.

Date: Thu, 24 Feb 2011 12:07:44 -0600
From: "Amy and Jim Rankin" <ajrankin at hughes.net>
To: "For Discussion of Anaerobic Digestion"
    <digestion at lists.bioenergylists.org
<http://us.mc782.mail.yahoo.com/mc/compose?to=digestion@lists.bioenergyl
ists.org> >
Subject: Re: [Digestion] Hydrogen sulfide - Biogas
Message-ID: <F761972DFB6C4622A2F5FE0F5EA3B1E7 at RankinPC>
Content-Type: text/plain; charset="utf-8"


  """""""""""""""""
  I am new on this list serve, I have a question regarding the danger of
H2S, I have been reading about this gas and its dangers, I am developing
a project in a rural community in Mexico, I'm helping to develop 5
tubular PE- biodigesters, I am still working on solve the Hydrogen
sulfide issue, I don't want to put people's life on risk; so, any help
on the manage or elimination  of Hydrogen sulfide on Bio-gas systems
will be helpful, 
  """""""""""""""""""""""""""""""
  If you control the biogas appropriately, you will mitigate the risk of
the hydrogen sulfide.  

  However, there are ways to scrub the biogas on the way out of the
digester (exposure to rusty steel wool, lathe turnings,shredded
sheetmetal etc) or it can be collected in the digester by admitting a
small amount of oxygen to the digester which causes the Sulfur to
collect as less dangerous forms within the digester, eventually passing
out with the effluent.  Sulfur has become an important plant nutrient in
these days of decreasing powerplant sulfur emissions here in the USA and
elsewhere in the developed world.  The amount of oxygen would have to be
regulated to stay below the level where the mixture becomes flammable.
Not quite so simple a technology as the poly tube digester you are
working with.  

  As part of your training for the operators of the digesters, you must
emphasize that the digester is a very dangerous place.  Not that a poly
tube digester is somewhere a person might ever go.  This is not only
because of hydrogen sulfide, but also because of the carbon dioxide and
methane.  Every year or two, someone (and sometimes several "rescuers"
as well)  is killed when they enter a pit or other place where the
biogas/manure gas has accumulated or is being liberated rapidly enough
to reach dangerous concentrations.

  Jim

  James R Rankin, DVM
  Cedarcrest Farms, Inc
  Faunsdale, Alabama USA

Matt Lorig
mattlorig at yahoo.com

 

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