Odors from mycelium sludge waste and bone meal manufacturing
Date: Oct. 13, 2004
This is a reply to request of information about gases from
- Landfill where mycelium sludge is dumped (from penicillin production)
- Bone meal production process.
This also includes information about the potential health effects of the gases causing the bad odors in both cases.
Odorous substances that have not being identified as toxic to humans
may evoke violent or alarming physical symptoms in a substantial
fraction of an exposed population whenever odor intensity is high and
exposure more than fleeting.
It is likely that the nuisances caused by the "fetid" or "stinking"
odors include a mixture of gases, some of them could have identified
toxic effects in humans, but they produce violent and alarming symptoms
in the exposed population. Any of these physiologic reactions to foul
odors result from the direct action of the odorous substance on
receptors that affect the autonomic nervous system. All these reactions
clearly represent a matter for public health concern and attention
under the Word Health Organization�s (WHO) definition (1958) of health
--"a state of complete physical, mental, and social well being and not
merely the absence of disease and infirmity" even though the chemical
components individually or collectively responsible for the foul odors
have not been specifically identified as toxic substances by the usual
Whenever the withdrawal of the foul odor results in prompt,
complete, and permanent remission of all the physiologic symptoms, this
might be accepted as a criterion for the absence of toxicity as
classically defined. Therefore the nuisance caused by the odors is
enough argument to file a petition to the authorities, not only based
on "the character of the odor, but also on the duration of the
exposure, time of day, day of week, intensity and frequency of
exposure". National Academy of Sciences (1979) "Odors from Stationary
and Mobile Sources".
I. PHARMACEUTICAL COMPANY - MYCELIUM SLUDGE WASTES
Methyl mercaptan and hydrogen sulfide are two possible gases that
match the description of the odor you mention from the pharmaceutical
company. I also included a general description of the industrial
production of penicillin.
According to your message, a pharmaceutical company is dumping
mycelium sludge in an open landfill and covered with coir and mud. It
is very likely that the odor comes from the decomposition of the
organic matter in the sludge.
The odours from the mycelium sludge could be a mixture of several
odor compounds produced by complex simultaneous chemical reactions that
occur during putrefaction. Indole (also called 2,3-benzopyrrole,
1-benzazole, benzopyrrole), is a subtance with characteristic fecal
Industrial biosynthesis of penicillin commonly involve the use of
corn steep medium used for the growth of the fungus Penicillium
chrysogenum during the fermentation process to obtain penillicin(the
production process also involves lactose, amino acids, mineral salts
and other substances).
Corn kernels on an intact plant accumulate indole-3-acetic acid
(IAA) at the rate of 190 ng g-1 fresh weight h-1. This substance is
produced by metabolic reactions that involve tryptophan.
The mycelial sludge not only is composed by pure fungal biomass but
it also contains other compounds formed during the production process.
After the mixture of substances called "mycelial sludge" is dumped in
the open space, it is subject to the action of groups of bacterias and
The microbiological breakdown of the fungal biomass (enriched with
the wastes of the corn medium) in the open dumpsite can produce indoles
(indole, 3-methylindole and other indole derivatives), as well as other
malodorous substances which include hydrogen sulfide, and others.
Information on the human health effects from exposure to indole is limited. http://avogadro.chem.iastate.edu/CHEM211L/MSDS/Indole.htm
Even if the "fetid" or "stinking" odors does not have identified
toxic effects in humans, they produce violent and alarming symptoms in
the exposed population. Any of these physiologic reactions to foul
odors (which are documented) clearly represent a matter for public
health concern and attention under the WHO definition of health.
The odors may alsocome from the decay of organic matter. This
degradation produces "methyl mercaptan" which smell like feces, and
"hydrogen sulfide", which are produced during the bacterial degradation
of organic matter in the sludge.
1. METHYL MERCAPTAN
If methyl mercaptan is released to soil, it probably then goes into
the air or is carried through the soil by rain or any other water that
contacts it. Sunlight can break them down in the air to other
Methyl mercaptan can be smelled and recognized in air at a level of
about 1.6 ppb (1.6 parts of methyl mercaptan per billion parts of air).
It can be smelled when it is present in water at a level far lower than
a. Health Effects
Methyl mercaptan is always present in the body, urine and feces in
small amounts. According to the U.S. Agency for Toxic Substances and
Disease Registry (ATSDR) very little is known about the health effects
of methyl mercaptan. A single case of death resulting from occupational
exposure to methyl mercaptan has been located. A 53-year-old Black male
laborer worked for
about 1 week emptying tanks containing methyl mercaptan. No details
of exposure level were available; however, it is assumed that both
inhalation and dermal exposure were probably involved. The man was
hospitalized in a coma, developed hemolytic anemia and
methemoglobinemia, and died 28 days after admission (Shults et al.
1970). The immediate cause of death was determined to be a massive
embolus that occluded both main pulmonary arteries.
It is not known whether long-term exposure to low levels of methyl mercaptan can result in harmful health effects.
Most studies of occupational exposure to methyl mercaptan in the
pulp industry also involve exposure to other sulfur-containing
compounds such as hydrogen sulfide, dimethyl sulfide, and sulfur
dioxide as well as to methyl mercaptan (Kangas et al. 1984). http://www.atsdr.cdc.gov/toxprofiles/tp139-c2.pdf
The EPA requires that discharges, spills, or accidental releases of
100 pounds or more of methyl mercaptan must be reported to the EPA. The
Occupational Safety and Health Administration (OSHA) has set a
permissible exposure limit of 20 milligrams of methyl mercaptan per
cubic meter of air (20 mg/m�) for an 8-hour workday in a 40-hour
The American Conference of Governmental and Industrial Hygienists
(ACGIH) and the National Institute for Occupational Safety and Health
(NIOSH) recommend an occupational exposure limit of 1 mg/m� for methyl
[See information about health effects and guidelines for hydrogen
sulfide in our memo: "Interpretation of the Results of air samples from
Cuddalore" Date: Aug 18, 2004]
Background information about the commercial production of
penicillin. The name penicillin is applied to a variety of compounds
produced by various species of Penicillium and also to many
semi-synthetic penicillins, produced by converting one antibiotic, such
as penicillin G, into another, such as ampicillin. Penicillin G, one of
the most active and widely used forms, is manufactured commercially
using Penicillium chrysogenum.
There could be several sources of air pollutants during the
production of penicillin, and as you mentioned, the solid wastes from
the production process could also be a source of odors.
The manufacturing process is carried out in stainless steel
fermenters of l0 000 dm3 capacity. The fermenter is steam sterilized
and loaded with sterilized growth medium (corn steep liquor) containing
lactose, amino acids, mineral salts and other substances.
(Phenylethanoic acid, a metabolic intermediate, is also added, to
increase the yield).
An inoculum of strongly growing hyphae is added. Both glucose and
nitrate are added periodically. The pH requires adjustment from time to
time, to neutralize ammonia produced by the fungus. Temperature is set
at first to give the maximum growth rate and then altered to favor
penicillin synthesis. The fermenter is continuously stirred and sterile
air blown in. An external cooling jacket is used for temperature
control. After about 160-200 hours, the broth is filtered. Penicillin
passes through in the filtrate, which is further processed to
crystallize the product.
Penicillin is a secondary metabolite, produced in large quantities
only towards the end of the growth period of the fungus. Therefore, it
is essential for all of the mycelium to reach peak growth at the same
time. This is why batch fermentation, rather than a continuous process,
is appropriate for penicillin manufacture.
II. BONE MEAL PRODUCTION - ODORS
The bone meal production process you describe may include a " Batch
Rendering Process" that causes vapor emissions from the cooker pass
through a condenser where the water vapor is condensed and non
condensibles are emitted as VOC emissions. Volatile organic compounds
(VOCs) are the primary air pollutants emitted from rendering operations.
The major constituents that have been qualitatively identified as
potential emissions include organic sulfides, disulfides, C-4 to C-7
aldehydes, trimethylamine, C-4 amines, quinoline, dimethyl pyrazine,
other pyrazines, and C-3 to C-6 organic acids. In addition, lesser
amounts of C-4 to C-7 alcohols, ketones, aliphatic hydrocarbons, and
aromatic compounds are potentially emitted. No quantitative emission
data were presented. Historically, the VOCs are considered an odor
nuisance in residential areas in close proximity to rendering plants,
and emission controls are directed toward odor elimination. The odor
detection threshold for many of these compounds is low; some as low as
1 part per billion (ppb). Of the specific constituents listed, only
quinoline is classified as a hazardous air pollutant (HAP).
Your message describes a gelatine/bonemeal manufacturing unit that
processes beef bones using HCl acid. The odor varies between that of a
"decomposing corpse" to "burning corpse."
Hydrogen chloride (HCl) is a very irritant gas. It tends to react
easily with the substances it gets in contact with creating other
substances. When inhaled, HCL causes irritation nose, throat, larynx;
cough, choking; dermatitis; its solution causes: eye, skin burns;
liquid: frostbite; in animals: laryngeal spasm; pulmonary edema. You
can find complete information about the health effects of HCl at: http://www.atsdr.cdc.gov/tfacts173.html
We would need more information about the process in able to give you
precise information of the health impacts of the emissions from the
bone meal plant. Usually emissions from these plants include groups of
substances with different toxicity. The fundamental question is that a
sizeable fraction of the population exposed to foul odors cannot live
with them in comfort and well-being. The effects of annoyance,
inconvenience, and irritation include sensory perceptions that are
reflected in physiological stresses that interfere with life quality