Hydrogen sulphide often results from the bacterial break down of organic matter, in the absence of oxygen, in waste water treatment plants. It is the chemical compound with the formula H2S. This colourless, toxic and flammable gas is responsible for the foul odour of rotten eggs and flatulence. Due to a very low odour threshold level, even small concentrations of H2S can be smelled in a wide radius from manholes, pumping stations, treatment plants and industrial factories. This results in complaints from people living in an area close to the source of the odour and often leads to negative publicity, media attention and a bad reputation.
In addition H2S is a highly toxic gas. It can poison several different systems in the body, although the nervous system is most affected. Exposure to lower concentrations can result in eye irritation, shortness of breath and fluid in the lungs. Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Higher concentrations of H2S even tend to be fatal. 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure and concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late.
The majority of the effluent that is received is high in sulphates, which in turn leads to the generation of H2S. However, anaerobic decomposition of organic material containing sulphur and nitrogen may also result in generation of other odorous compounds (mercaptans, amines and volatile fatty acids). The nature of the effluent and treatment processes employed is a factor in determining likely odour emissions. In general, different compounds dominate odour emissions from different processes on site. For example, H2S is generally associated with inlet works emissions, while mercaptans would be associated with sludge treatment processes.
Pure Air Solutions has extensive experience in odour emissions from wastewater treatment plants and supplies biological and chemical solutions that provide astonishing treatment results for your emission problems. Both our biological Sulphus and our chemical scrubber have successfully been implemented at municipal and industrial waste water treatment plants.
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