INTRODUCTION
Recently, people in many countries have encountered numerous air pollution problems,
especially those associated with bad odour. It is well known that more than three
hundred substances can cause this problem, but hydrogen sulphide is the ones that often
exist in our surroundings. Large amounts of H2S is generated and released from
industrial processes, such as wastewater treatment, petrochemical refining, etc. Excess
of these substances have to be removed for the sake of safety and health and also for the
reduction of environmental impacts, so a growing awareness and concern for air quality
is driving a search for economical and efficient abatement technology to reduce the
impact of the industry in the environment.
Usually, the concentrations of these odorous compounds in the gas emissions are so
dilute, traditional air pollution control technologies such as incineration, adsorption or
chemical scrubbing tend to be costly and are associated with their own pollution
problems. So, based on the cost for the equipment and operation, biological treatment is
believed to be the most economical option for treating ammonia and hydrogen sulphide.
Ammonia is colourless, but irritant and smelly, while hydrogen sulphide is corrosive,
extremely toxic, and also smelly.