Miura 8,000 liter/hour dynamic water sterilization system uses Nichia UV-C LED

Nichia previously temporarily suspended the blog post series "Nichia's Contribution to a Mercury-Free Society", but recently it was reported that Japanese manufacturer Miura Industries (also a customer of Nichia) has launched a new UV LED water sterilization device, which has successfully replaced the traditional mercury lamp system. Taking the characteristics of this product as an example, the following will explain the reasons why Miura Industrial was able to replace mercury lamps with LEDs, as well as the various advantages brought by the use of LEDs.

There are various types of mercury-containing lamps on the market, but this article focuses on low-pressure mercury lamps, so-called germicidal lamps. In food and pharmaceutical plants, germicidal lamps are commonly used to disinfect cleaning agent water and equipment that comes into contact with products.

In terms of light source alone (rather than the overall system), the energy conversion efficiency of low-pressure mercury lamps is about 20% to 30%, and the conversion efficiency of UV-C LEDs when used only as a light source is even lower, causing some manufacturers to be reluctant to use UV LED germicidal lamps. The EU RoHS (Regulations on the Ban and Restriction of Hazardous Substances in Electronic and Electrical Equipment) even specifically excludes mercury lamps because of the "lack of replaceable technology." However, the selection is only based on the conversion efficiency of the light source. Lamps are actually not a reasonable approach, but the advantages of LED itself must also be considered. In terms of current performance, LED is ready to become an alternative technology. Many factories around the world have begun to use UV LED water sterilization equipment.

Figure 1 Schematic diagram of radiation irradiation treatment

As shown in Figure 1, in the traditional water sterilization device, the low-pressure mercury lamp emits ultraviolet rays to the surroundings, and the mercury lamp is surrounded by many pipelines. This design will cause the ultraviolet light to immediately hit the inner tube of the device, which will waste the ultraviolet radiation energy and ultimately reduce the utilization rate of ultraviolet light.

On the contrary, the small size of UV LED allows more freedom in device design and is not limited in shape. The design can also maximize the utilization of ultraviolet rays, thereby achieving a sterilization effect similar to that of a low-pressure mercury lamp.

Another benefit of changing the upright low-pressure mercury lamp to a UV LED light source is that the device can be miniaturized, saving the space required to replace the light source, and reducing the installation space by about 75%. In addition, mercury lamps may be damaged when replaced, causing risks such as glass breakage or mercury leakage. In contrast, UV LED light sources do not have such risks, so they have to reduce installation restrictions and increase freedom of use.

Figure 2 Switching to UV LED makes maintenance easier and saves installation space

Due to the long restart time of mercury lamps, mercury lamps must be kept on, but LEDs do not have this problem and can be turned on and off quickly. The power supply of the LED device can be turned off when the water flow is not temporarily used or sterilization is not needed.

In addition, when the flow rate is lower, the amount of UV radiation required can also be reduced, and the dimming function of the LED can further adjust the radiant flux output. These UV LED properties can reduce energy consumption, thereby lowering CO2 emissions.

Table 1 Comparison chart between low-pressure mercury lamp and UV LED

Summary:

This case analysis shows that although the energy conversion efficiency of LED light sources is lower than that of mercury lamps, the unique functions of UV LEDs can make LED devices an alternative option for water sterilization applications. Switching to UV LED also brings many benefits. It can not only save installation space, but also shorten machine operation time by taking advantage of its fast switching characteristics.

Nichia plans to continue to improve UV LED technology, so that UV LED will not only replace low-pressure mercury lamps in the water sterilization market, but also expand its application to various sterilization fields. Nichia also hopes that with the development of UV LED technology, RoHS will include low-pressure mercury lamps in the prohibited and restricted list in 2027, thereby reducing environmental pollution caused by related applications.

Nichia will continue to work hard to help the entire society achieve the goals of mercury-free and carbon neutrality. (Source: Nichia Chemical)

TrendForce 2025 Deep UV LED Market Trend and Product Analysis

Publication date: March 31, 2025 / September 30, 2025
Language: Chinese / English
Format: PDF / EXCEL
Number of pages: 50-60 / half a year