Eric Valdés, PhD student from the research group GENOCOV at Universitat Autònoma de Barcelona, performed a two-month secondment in Italprogetti Spa, also collaborating with Università degli Studi di Firenze, aiming at developing a mathematical model that is able to describe the dynamics of the partial autotrophic denitrification process occurring in a CSTR fed with nitrate and sulphide, as well as to predict nitrite accumulation for different influent conditions. This work will be helpful for understanding which conditions might be optimal for an integrated biological treatment of sulphur- and nitrogen-containing liquid streams such as tannery-like wastewaters.