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. (c) 2013 Elsevier B.V. All rights reserved.