IUVA World Congress 2021

UV-lamps and advanced oxidation processes

Every two years the International UV Association (IUVA) organizes a world congress. Last year, due to Covid, the congress was postponed, but this year it was held in a digital way. There were presentation on all kinds of developments, related to UV. I attended the sessions on UV lamp developments and advanced oxidation processes.

UV-lamp developments

Standard UV lamps contain mercury, and the fact that many countries try to limit its use is an important reason why different types of UV lamps are being developed. At the moment the EU is preparing new legislation, with the aim to reduce the use of mercury. However, as at the moment no adequate alternatives are available for large scale applications, like the centralized production of drinking water, it is expected that the exception for Hg-containing UV lamps will be prolonged.

Due to Covid disinfection applications with UV got a real boost, and this resulted e.g. in the increase in the use of DBD lamps for small scale disinfection. Also the development of UV-C LED lamps was stimulated. These lamps now are available for point-of-use applications, and have some very interesting properties, like the fact that they can be used instantaneously and offer design flexibility. These advantages seem to outweigh their disadvantages, like an low efficiency ≤ 10 % and a low output between in general 1 and 10 W/cm. At the moment yearly already about 120,000 UV LED lamps are sold, and in total already 60,000 m3 can be treated per hour (but only in small scale applications). The development of UV LEDs has gained momentum, and more and more applications are becoming possible.

New advanced oxidation and reduction processes for the removal of organic micropollutants

There are several advanced oxidation processes (AOPd) that can be based on UV. UV/H2O2 is the most well-known type of process, but during the conference much attention was paid to UV/Cl processes, especially in countries where Cl is used for primary disinfection purposes. The main disadvantage of this process is the formation of chlorine containing byproducts, and the prevention of these compounds.

Another AOP that gained much attention is an AOP based on Vacuum UV (VUV) radiation with a wavelength < 200 nm. The main advantage of this process is that it doesn’t require the addition of chemicals. As the penetration depth of this radiation is very low, application of VUV processes requires different reactor geometry.

Reduction processes, like UV/SO3, also were presented. The KWR presentation, from research carried out within the framework of the joint research program of the Dutch drinking water companies, also was about this topic. Applying the process under vacuum conditions and preferably with a wavelength of 185 nm may be suitable for the removal of PFAS from drinking water.