Appliance for treating a fluid

The invention relates to an appliance for treating a fluid, which appliance comprises an elongate hollow body made of two hollow parts 1, 2 which can be joined together, each part 1, 2 having a connection 8 for a fluid line 6, a multiplicity of longitudinal guides 11 being provided for holding at least one elongate vessel 10 by which guides this vessel is held at a distance from the inner wall 23 of the respective part 1, 2. According to the invention it is provided that the longitudinal guides 11 are formed in one piece with the inner wall surface of the parts 1, 2, that a vessel is received by each of the two parts 1, 2, which vessel is inserted from the side opposite the respective connection 1 of the part 1, 2, that each vessel 10 is formed by a closable glass bottle which is filled with a treatment medium and is tightly sealed and is disposed with its bottom 26 at a slight distance 27 from the base surface of the respective part 1, 2, so that the vessels 10 are oriented with their closure 13 in the direction towards the connections 8, the space 27 being filled by an elastic interlayer 18.