Abstract: An ultraviolet irradiation device that is used for a fluid to be irradiated having a low ultraviolet ray transmissivity, a spirally wound tube in which the fluid to be irradiated flows is supported and fixed, and an irradiation amount of ultraviolet rays with which the fluid is irradiated is increased. A tube 3 having ultraviolet ray transmitting property is spirally wound on an outer circumferential surface of a support pipe 5, a plurality of ultraviolet lamps 7 are disposed around an axis of the support pipe apart from the tube, an inner case 9 that supports the support pipe and that encloses the plurality of ultraviolet lamps is provided, and a fluid flows in the tube and is irradiated with ultraviolet rays. The tube which is a fluid channel is thereby fixed to the support pipe, so that breakage of the tube and the ultraviolet lamps 7 can be prevented.

Abstract: Filtration apparatus prevents a membrane filter from fouling by providing a UV irradiation apparatus. The filtration apparatus comprises a filtration tank which contains a membrane filter with a pore size of 0.1 to 1 &mgr;m connected to the UV irradiation equipment, an air diffusing pipe placed below the membrane filter, an air blower for sending air to the air diffusing pipe, a filtrate discharge pipe connected to the membrane filter, a flow meter and a flow control valve.