Producing biogas from organic fermentation substrate in anaerobic process, comprises converting hydrogen sulfide using iron hydroxide, which is obtained as by-product during drinking- or groundwater treatment, into iron sulfide

摘要

Producing biogas from an organic fermentation substrate in an anaerobic process, with low hydrogen sulfide content, comprises converting hydrogen sulfide using iron(III) hydroxide, which is obtained from aqueous sludge as a by-product during the treatment of drinking water or groundwater, into iron sulfide. The sludge is first subjected to mechanical drying and then to thermal drying to obtain a dry grain mixture, from which powdered iron(III) hydroxide is obtained, which is mixed with the fermentation substrate with homogeneous distribution, before carrying out anaerobic process. Producing biogas formed from an organic fermentation substrate in an anaerobic process, with low hydrogen sulfide content, comprises converting hydrogen sulfide using iron(III) hydroxide, which is obtained from aqueous sludge as a by-product during the treatment of drinking water or groundwater, into iron sulfide. The sludge is first subjected to mechanical drying until the dry matter content of the sludge is 18-35% and then to thermal drying to obtain a dry grain mixture with a grain size of up to 10 mm, from which powdered iron(III) hydroxide with a particle size of 0-0.5 mm is obtained by classifying and/or grinding, and the powdered iron(III) hydroxide is mixed with the fermentation substrate with homogeneous distribution, before the anaerobic process.