M E Henry Bergmann
Anhalt University of Applied Sciences, Germany
Title: (Electro)chemical water disinfection – challenges for the 21st century
Biography
Biography: M E Henry Bergmann
Abstract
Whereas worldwide hundreds of millions of people do not have access to safe drinking water, in developed countries current research and practice are oriented towards problems of micropolutants and disinfection by-products formed at µmole-per litre level. Another special subject of activities is the low-chemical disinfection of process waters in recirculation and cooling systems. Although direct electrochemical drinking water disinfection is applied for decades of years, conditions for avoiding over chlorination and disinfection by-products could only be clarified in the recent years. A new approach is the electrochemical generation of chlorine dioxide (ClO2) at mm concentration level. It is well known that ClO2 has much lower organic by-product formation potential compared to free active chlorine. The challenge is to minimize chlorite, chlorate and perchlorate in the solutions obtained. The high chlorite reactivity often causes maxima in ClO2 formation. Highly active anodes dramatically reduce the generation of chlorine dioxide due to parasitic reactions. Solutions for inorganic electrolysis and disinfection by-products can be found by analysing and studying influence parameters such as temperature, electrode material, counter electrode material and cell construction. ClO2--to-ClO2 yields of 75% are possible at the moment. Furthermore, it is discussed if combined methods may contribute to lower by-product formation. A simple variant is the combined chlorine-chlorine dioxide formation. The combination of ozone and chlorine dioxide in situ is another interesting option. First own experiments have shown that all initial chlorite can be converted to chlorine dioxide. Lower temperatures in the range of 5℃ are preferred reaction conditions. It can be stated that in the future improved regulations and inline analysis methods have to be applied for safer disinfection. Means of digitalization could support the process.
