UV UV rays are electromagnetic radiation with a wavelength of about 4 – 400nm. The wavelength of the ultraviolet ray is beyond the perceived and perceived range of the naked eye. Using ultraviolet light for sterilization does not change the chemical and physical properties of the water.
Ultraviolet rays change the DNA of bacteria cells, ultraviolet rays have a wavelength of 254 nm, the highest ability to kill bacteria. In wastewater treatment plants, using low-pressure mercury lamps to emit ultraviolet rays, these lamps emit ultraviolet rays with a wavelength of 253.7 nm, lamps placed in glass boxes do not absorb ultraviolet light. , separate the light from the water. The light is installed in a set in a container with a distribution baffle so that when water flows through the box, it is mixed well to allow the highest number of bacteria to pass through the lamp during the contact time in the box. The water layer passing through the lamp is about 6mm thick, the energy consumption is from 6000 – 13000microwatt / s, the endurance is 3000 hours to 8000 hours.
However, when using this method, the cost is very high. Recent experiments show that wastewater with suspended sediment content SS <50mg / l, after passing through an ultraviolet light box with the above energy standard, the water is 200 Coliform / 100ml.