Supplementary treatment for the removal of polar organic micropollutants

Technology

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.

Challenge

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.

Solution

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.