[Natalia Bourenane]

@biogazeg , @Maxime I wonder if you can share your experience?

[Maxime]

The CAPEX and OPEX analysis in regard of the gas quality dictated our choice.

[Ryan]

Do any of our desulfurization experts from @Anka.Enerji , DMT @Nikolas_Pat or @Paques @desotec_louis want to jump in on this?

[Hatem]

Industry trends suggest that for high H2S levels (e.g., 6,000 ppm), operators often prefer biological or liquid redox systems for their efficiency and lower long-term costs, especially in large-scale plants. For smaller facilities or lower H2S levels (e.g., 100 ppm), activated carbon or iron oxide systems are more common due to their simplicity and lower upfront costs.

[Peter]

The technologies used for anaerobic digesters and landfills might be different because it is often beneficial to do some hydrogen sulfide treatment in the digester, while this level of control is not possible in a landfill.

Why is in-situ treatment beneficial?

In anaerobic digesters 6,000ppm H2S likely indicates high dissolved sulfide concentrations. Dissolved sulfides can inhibit anaerobic digestion -reducing biogas yields and throughput. Dissolved sulfides can also bind to trace metal nutrients and cause nutrient deficiencies.

What are in-situ treatment options?

Hydrogen sulphide can be consumed by sulfur oxidizing bacteria in the digester headspace or iron can be added to react with dissolved sulfides and prevent them from becoming gas. Air injection paired with a sulfur net inoculated with sulfur oxidizing bacteria can be one of the cheapest options however air injection can also make it more challenging to hit strict RNG quality targets.

With or without air injection iron can be added as iron chloride solution, iron oxide powder, or iron hydroxide powder to react with sulfide in the digester and quickly reduce sulfide concentrations in the biogas.