Ultraiolet Germiidal Lemp;Low-pressure mercury lamp can give out ultraviolet light of 254nm and 185nm. The light of 254nm has strong germicidal function and the light of 185nm can ionize the air to produce the ozone,which also has the germicidal function and can oxidate and decompose the organic substance in water. The ultraviolet light also can promote the photochemical reaction to degrade the harmful substance.