Hello Michael
methanol my biodegrade but into what?
Umm, a little lower down it says: ... which are capable of
completely degrading methanol to carbon dioxide and water.
Yon carbon dioxide is a greenhouse gas because the methanol would
almost certainly be fossil fuel-derived, but it's going to be
released whatever you do with the methanol, including making
biodiesel with it and burning it in your motor.
So what do you do with your wash-water? Do you recover the excess
methanol from the biodiesel portion before washing?
Best wishes
Keith
if it degrades into methane that is a green house gas?
Original Message Follows
From: Keith Addison [EMAIL PROTECTED]
Reply-To: Biofuel@sustainablelists.org
To: biofuel@sustainablelists.org
Subject: [Biofuel] Methanol and wastewater treatment systems
Date: Mon, 10 Oct 2005 02:10:47 +0900
9.1.1 Microorganisms
The toxicity of methanol to each of three bacterial groups, i.e.,
aerobic heterotrophic, Nitrosomonas and methanogens (key agents in
the natural recycling of organic material in the environment and in
wastewater treatment systems), was described by Blum Speece (1991).
The following IC50 values (mg/litre) (the concentration that
inhibited the culture by 50%) compared to the uninhibited controls
were reported: Nitrosomonas (after 24-h exposure), 880 mg/litre;
methanogens (after 48-h exposure), 22 000 mg/litre; and aerobic
heterotrophs (after 15-h exposure), 20 000 mg/litre. Methanol was
found to be completely inhibitory to ammonia oxidation by
Nitrosomonas bacteria at a concentration of 5 x 10-3 M (about 160
mg/litre) (Hooper Terry, 1973)...
... An experimental EC50 value (the concentration that reduced the
maximum observed biodegradation rate by 50%) for methanol of 2.8
mol/litre (89.7 g/litre) was obtained in a system employing an
enriched mixed microbial culture derived from domestic waste water in
the USA (Vaishnav Lopas, 1985).
9.2.1 Plants
Hemming et al. (1995) determined the effect of methanol on the
respiration of pepper (Capsicum annuum), tomato (Lycopersicon
esulentum) and petunia (Petunia hybrida). Whole plants were exposed
to either methanol vapour or methanol solution. The general response
to methanol was the same for the three species, with a respiratory
rate increase of up to 50% at the lower methanol concentrations
tested. The response was the same for exposure to methanol vapour or
solution. Exposure of a single leaf resulted in a systemic response
throughout the whole plant within a few hours. The response lasted
for several weeks. Decreased metabolic rates and waterlogged
appearance were reported in plants following a brief exposure of a
leaf to methanol concentrations 30%. Root tissue was reported to be
more sensitive; a decrease in metabolic rate was reported following
brief exposures to 10% methanol.
10.2 Evaluation of effects on the environment
Methanol is readily degraded in the environment by photo- oxidation.
Half-lives of 7-18 days have been reported for the atmospheric
reaction of methanol with hydroxyl radicals.
Methanol is readily biodegradable under both aerobic and anaerobic
conditions in a wide variety of environmental media. Many genera and
strains of microorganisms are capable of using methanol as a growth
substrate. Generally 80% of methanol in sewage systems is biodegraded
within 5 days.
Methanol is a normal growth substrate for many soil micro- organisms,
which are capable of completely degrading methanol to carbon dioxide
and water.
Methanol is of low toxicity to aquatic and terrestrial organisms and
it is not bioaccumulated. Effects due to environmental exposure to
methanol are unlikely to be observed, unless it is released to the
environment in large quantities, such as a spill.
In summary, unless released in high concentrations, methanol would
not be expected to persist or bioaccumulate in the environment. Low
levels of release would not be expected to result in adverse
environmental effects.
-- From: United Nations Environment Programme / International Labour
Organisation / World Health Organization: International Programme On
Chemical Safety, Environmental Health Criteria 196 - Methanol, from
IPCS INCHEM, Chemical Safety Information from Intergovernmental
Organizations, in cooperation with the Canadian Centre for
Occupational Health and Safety (CCOHS)
http://www.inchem.org/documents/ehc/ehc/ehc196.htm
FWIW I think 22 000 mg/litre is 2.8 per cent.
Best wishes
Keith
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