Earlier research showed that significant concentrations of pharmaceuticals and other organic micropollutants were present in the Limburg watercycle, and that these concentrations would increase in the future. This motivated WML to conduct pilot research at WP Heel, in order to study whether an advanced oxidation process based on UV/H2O2 would be a suitable means of removing all kinds of organic micropollutants from the drinking water.
UV/H2O2 processes are very effective in removing organic micropollutants like pharmaceuticals from water. Their big drawback, however, is that they consume quite a lot of energy. Earlier KWR research work developed a model for the purpose of optimising the geometry of UV reactors for advanced oxidation processes. One reactor designed on this basis was built by Van Remmen UV-Techniek and used in the pilot set-up at WP Heel. The research studied how effective the process is for the breakdown of pharmaceuticals, sweeteners, EDTA, NDMA, AMPA, and DMS, and how it could be optimised.
A pilot set-up was built at WP Heel, which used a UV reactor designed and built for advanced oxidation. The process was run for almost a year and its operation tested. In addition, dosage tests with pharmaceuticals and other organic micropollutants were conducted to study the effectiveness of the process in breaking down such substances; how the process could be optimised was also researched. An examination was further made of the possible formation and breakdown of transformation products.
The high UV-T of the bank-filtration water from WP Heel showed that the UV process is particularly effective. It required relatively little energy to reach a specific UV dosage and, thanks to an improved reactor geometry, the dosage needed for the transformation of pharmaceuticals was also low in comparison with other large-scale UV/H2O2 processes (≤ 300 mJ/cm2 compared to the 500-600 mJ/cm2 applied in water practice). It is also possible to lower the H2O2 concentration, but attention has to be paid to avoiding the formation of too many transformation products. This process is also effective for sweeteners and EDTA, but to achieve a sufficient transformation of DMS the UV dosage cannot be reduced too much.