Hydrogen sulphide is a common problem in biogas collected from landfills. Hydrogen sulphide is corrosive and has to be removed before further utilization of biogas. ARTASFin can deliver different methods depending on amount of biogas and its composition.
Biological method is a common sulphide removal process. Thiobacillus ja Sulfolobus bacteria can be used to oxidize hydrogen sulphide into elementar sulphur or sulphuric acid. The biogas flows through biofilter, where the bacteria grow on filter media. The process requires small amounts of nutrient and oxygen addition for optimal treatment efficiency.
In wet chemical desulphurization, hydrogen sulphide is aborbed into NaOH solution in a counter-current scrubber. The H2S is then converted into NaHS, which stay in the solution. One of the problems is disposal of spent cleaning liquid. The process can be combined with biological treatment, where the bacteria regenerates the NaOH solution.
There is also a so called dry chemical treatment. It is based on granulated ferric hydroxide (Fe(OH)3). The biogas flows through a filter made of granules and the hydrogen sulphide reacts with ferric hydroxide forming solid ferric sulphide (FeS) on the surface of the granules. In this method, the spent material has to be replaced in certain intervals. The spent material can be disposed into landfills.