Hydrogen sulphide removal from biogas by an anoxic biotrickling filter packed with Pall rings

• ORP measurement can be used for nitrate supply control.
• Biogas desulphurization was achieved without a reduction in methane concentration.
• A high ECCRIT of 120 g S m−3 h−1 can be achieved using polypropylene Pall rings.

Hydrogen sulphide (H2S) is one of the most problematic contaminants in biogas. In this study, a biotrickling filter with a working volume of 2.4 L and packed with polypropylene Pall rings was tested for its ability to remove H2S from biogas under anoxic conditions. The influence of the H2S inlet concentration, nitrate feeding regime (manual and controlled) and liquid flow rate on the elimination capacity of the biotrickling filter was studied. The results indicate that 99% of the H2S was removed for H2S inlet loads lower than 120 g S m−3 h−1 when using controlled nitrate feeding by ORP.