Anaerobic removal of sulphur compounds from waste water

Method for anaerobic removal of a sulphur compound from waste water containing said compound, the method comprising the steps of:

• 1) feeding the waste water to an anaerobic digestion system;
• 2) converting the sulphur compound in the digestion system to a sulphide;
• 3) circulating an effluent containing the sulphide from the digestion system in a bypass channel, said channel comprising a stripper system for stripping the sulphide from the effluent;
• 4) removing the sulphide from the effluent by contacting with a transporting gas in the stripper system;
• and
• 5) converting the sulphide to sulphur;
• wherein the sulphide is absorbed from the transporting gas in an absorber system by an absorbing liquid, which absorbing liquid is passed in a first closed loop through the absorber system thereby minimizing release of carbon dioxide in the step of converting the sulphide to sulfur, and the transporting gas is passed in a second closed loop through the stripper system and the absorber system.