Apparatus for ultraviolet irradiation and disinfection of flowing sewage with reduced UV transmission coefficients

摘要

Each UV module (14) has an irradiation volume with polygonal cross section, its center (18) corresponding with that of the UV source (26) and extending up to half the spacing between sources. Individual UV modules (14) are arranged so that their centers form corner points of a polygon (20), its area being the sum of cross sectional areas (F1) of UV modules. Inter-module spacing is selected such that the cross sectional area (F2) of the irradiated volume (24) of each module is no more than ten times larger than the cross sectional area (F1) of the individual UV-module. An Independent claim is also included for the corresponding method of UV irradiation. Emitted power is 0.5 W/cm of discharge length, flow velocity exceeding 0.25 m/s. Module diameter is 30 mm or more. Preferred features: In a chamber, a frame holds the modules parallel in the flow direction (A) immersed in the fluid. Low pressure mercury vapor tubes are used. The lamp is amalgam doped, its diameter 2.0 cm, the inner casing tube diameter being 6 mm and at most 30 mm greater than the outer diameter of the UV source. The cross sectional area (F2) of the irradiation volume of each module exceeds 7.5 times the cross sectional area (F1) of the UV module allocated to it. The high power UV source has a 1.2 m discharge length, emitting radiant power exceeding 60 watts of UV-C per meter. The source has an outer diameter of 20 mm, preferably 30 mm. Through-flow is laminar. A power control circuit is included for the UV sources, at least two being connected to one controller. Power is regulated for constant UV irradiation, and in accordance with the UV transmission of the fluid and its flow rate. Flow rate is 0.4 m/s. Irradiation intensity at the tube surface is 60 mW/cm2 in the waveband 200-280 nm.