The present invention relates to the field of biological and chemical transformation as well as physical and chemical trapping. More specifically, the invention relates to a new reactor arrangement for performing, by means of at least one solid reaction member, biological or chemical transformation, or physical or chemical trapping from or release of agents to, a fluidic medium. The reactor arrangement is comprised of an auxiliary reactor having a transformation device and a main reactor. The invention also provides an auxiliary reactor adapted for being connected to a main reactor, a method of using such a reactor arrangement, as well as a process involving the reactor arrangement.
