Liquid treatment apparatus with replaceable treatment cartridge and cartridge connection system

A device for forming a liquid treatment apparatus when combined with a replaceable liquid treatment cartridge, the device comprising:

• a main part;
• and
• a receiving part comprising a cavity for receiving a connecting head of the replaceable liquid treatment cartridge having at least one port in liquid communication with an interior of the replaceable liquid treatment cartridge such that the at least one port(s) of the connecting head are in sealed liquid communication with corresponding respective ports of the receiving part for transfer of liquid between the device and the replaceable liquid treatment cartridge to allow the replaceable liquid treatment cartridge to effect a liquid treatment,
• wherein the receiving part is journalled for movement between a first and a second position with respect to the main part whilst the connecting head is inserted in the cavity,
• wherein the connecting head is insertable into and re-tractable from the cavity in the first position,
• wherein the replaceable liquid treatment cartridge is lockable to the device by at least moving the receiving part with the inserted connecting head into the second position, and
• wherein the movement comprises a component corresponding to an intrinsic rotation in a plane parallel to a direction of insertion about an axis of rotation, and
• wherein the movement further comprises at least a component corresponding to a displacement of the entire receiving part and thus of the axis of rotation relative to the main part.