To: "Biomass List Crest"
Mary Gayman rightly points out the dangers of H2S and my heart goes out to the families of the workers who so needlessly died from the toxic effects of this much under-rated danger.
Biogas typically has 10,000ppm of H2S and even after sludges and manures are treated with massive doses of ferric chloride they end up at 200-400ppm H2S. The Occupational Exposure Standard which must not normally be exceeded for an individual worker is 10ppm. Between 1987 and 1995, no fewer than 29 people lost their lives in H2S related gasings with more than 1400 non- fatal incidents being reported to US Poison Control Centres each year for 1994 and 1995.
Lives can be saved by means of a warning bleeper which is set off at 5ppm and above. These cost no more than 50p pence (80 US cents) per working day and weigh only 2 ounces! Such detectors are compulsory items in well run sewage works and should be fitted along with hard hats and yellow jackets on every biogas site. Life is simply worth more than 80cents a day! If you want a bunch of detectors let me know.
Director Practically Green Environmental Services
Solar House Magherafelt BT45 6HW Northern Ireland +44 1648 32615 Tel./Fax
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Updated 22 January 2004 by Paul Harris