What is Hydrogen Sulphide?? this is known as H2s, also known in the natural gas fields as Sour Gas

Hydrogen sulphide can be present in various air streams and is often found in gas streams associated with petroleum storage and transfer facilities, anaerobic digesters, sewage treatment plants and pulp and paper mills. In many cases, the hydrogen sulphide has to be removed because of its toxicity, corrosive properties and unpleasant odour.

HOW HYDROGEN SULPHIDE IS FORMED

Hydrogen Sulphide is formed as a result of decomposing animal manure. The decomposition process begins as soon as it is excreted by the animals. Micro-organisms utilize the manure to synthesize new cellular material and to furnish energy for synthesis. This process takes place with or without oxygen. However, the type of microbes, and the type of gases that are produced, are dependent on the type of environment in which degradation takes place. In anaerobic conditions (without oxygen), typical of most liquid manure systems, hydrogen sulphide will be given off.

Hydrogen sulphide is produced continuously in all un-aerated manure storage systems, including shallow barn gutters, underground storage tanks or outside manure holding ponds or lagoons. Depending on temperatures and other factors, the rate of release of the gas is slow in undisturbed storage.

PROPERTIES OF HYDROGEN SULPHIDE

Hydrogen sulphide is a clear, colourless gas that can be identified in relatively low concentrations, by a characteristic "rotten-egg" odour. Hydrogen sulphide is approximately 20 percent heavier than air, with a specific gravity of 1.19. Hydrogen sulphide odours can be recognized in concentrations of less than 1 mg/kg (air). The odour of hydrogen sulphide will increase as the gas becomes more concentrated. However, in concentrations of 150 or greater mg/kg (air), a person's ability to detect the gas is affected by temporary paralysis of the olefactory nerves in the nose. Owing to this unique property of Hydrogen sulphide, relying totally on the sense of smell to warn against the gas, can be extremely dangerous. In high concentrations, the ability to smell the gas is lost instantaneously, the disappearance of the odour could mean that the gas concentrations have increased.

PHYSIOLOGICAL EFFECTS OF HYDROGEN SULPHIDE

Hydrogen sulphide is classified as a toxic chemical, in high concentrations it will lead to almost instantaneous poisoning and death. High concentrations will result in the complete arrest of respiration. A person over come by this gas should promptly be removed from the contaminated area and given immediate artificial respiration.

Exposure to lesser concentrations may result in nausea, stomach distress, belching and coughing. Moderate concentrations may result in eye irritation.

PROPERTIES OF HYDROGEN SULPHIDE *

Chemical Formula H2S
Odour Rotten Egg
Boiling Point 60° C
Odour Threshold 0.13 mg/kg (Oxygen)
Specific Gravity 1.19
* American Industrial Hygiene Assoication, 1962.

PHYSIOLOGICAL RESPONSE OF ADULT HUMANS TO HYDROGEN SULPHIDE **

Effect Concentration
Mg (H2S)/1 Kg (Air)
Least Detectable Odour 0.01-0.7
Offensive Odour 3-5
Eye Irritation 10
Irritation Mucous Membranes
  and Lungs		 20
Irritation of Respiratory Tract 50-100
Olefactory Nerve Paralysis 150
Headache, Dizziness 200
Nausea, Excitement,
  Unconsciousness		 500-600

Copyright 2003 Mountain State Natural Gas Recovery