Multiple UV sterilizers may be connected in series in order to increase the microorganism kill rate. The UV sterilizers are rotatable with respect to other UV sterilizers so that the UV sterilizers may be combined in various configurations in order to adjust a level of UV sterilization and allow combination of UV sterilizers in various configurations. For example, a combination of two or more UV sterilizers may be configured in a first orientation if the UV sterilizers are to be placed in a narrow space, while combination of the same UV sterilizers may be adjusted to another orientation if the sterilizers are to be placed in a large, open space.