Hello Linas,

Did you try micro-oxygenation of the digester to reduce the H2S levels in the digester? The problem can come from the input of your digester, a high sulphur content might result in high H2S levels obviously. This article proposes a model for the H2S content in the biogas from the input composition : 

http://www.sciencedirect.com/science/article/pii/S0960852412010267

To answer about the ashes, a publication found that the adding of ashes from municipal incinerator has a positive effect on the digestion which could come from the trace metals added or the increased electroconductivity (induced by the trace metals). However with wheat ashes I have no idea how this could affect the digestion. 

http://www.sciencedirect.com/science/article/pii/S0960852412004130

Please let me know if you solve the problem and how you did so, since these levels of H2S are quite high.

Gabriel

Hi Linas,

You might want to consider to add a iron hydroxide rich compound first to reduce the H2S level, e.g. FerroSorp®. Otherwise, too many of the trace elements you add might precipitate as sulfide. Anyway, it would be an interesting study to compare the cost between the ash you propose and other commercial products. Of course, you would need to check if the ash contains some other inhibitory substances that might damage the anaerobic digestion process.

Best,

Fabian

Fabian, 

We already use Fe(III)Cl for H2S removal purpose. Also, we inject air to the headspace of digester. 

But H2S volumes are too high, I consider mirconutrients addition - but maybe the smart (cheaper) alternative would be ash addition?