Development of a water sterilization UV reactor with measurement of oxidation rate to verify the quality, the process, and the output parameters of the cleaning by using new kind of UV LEDs

In the field of water treatment and analysis, it is necessary to continuously research and develop processes and optimize their efficiency. This is due to the constant occurrence of new types of pollutants, especially in industrial processes, the evolution of resistant microorganisms and the global need for energy change. In this thesis, three closely related projects have been carried out, to form an innovative modular system for water analysis and treatment. The first objective was to validate a measurement principle for total organic carbon (TOC) (part (I)). In order to improve this system and to find new UV sources, an experimental UV disinfection setup was built and evaluated using novel LEDs (part (II)). The results of part II could not be used for part I, but the disinfection performance results were then applied to construct one or more modules for the development of a transportable, modular integrated system (part (III)). (I) The first subproject aimed to develop and validate a prototype for automated water analysis of very high concentrations of total organic carbon. The method is based on the radiationinduced dissociation of organic molecules to CO2 and water. The TOC content is derived from the resulting change in electrical conductivity. Due to their sensitivity, conventional sensors provide accurate results only in a limited range between 0 and 1000 ppb or use a complex or error-prone analysis method. The integration of a specially developed dilution control system in the 2.20 m x 1 m x 1.20 m sized prototype allows continuous measurements of samples with about 30 000 ppb of TOC in a specific precision range. Even samples with 2 000 000 ppb of TOC could be measured with a higher error range of up to 49 %. The TOC prototype is intended for continuous use in water-bearing sites for continuous automated sample analysis. (II) In the second subproject, new types of low-cost UV-C LEDs (ultraviolet-C light-emitting diodes) were investigated in detail concerning their suitability for water treatment. The focus was on the disinfection properties in combination with parameters such as flow rate, voltage changes and emission spectra. In addition, combined processes with heat, ultrasound, and as a negative example with ozone were investigated in samples with high microbial contamination. In an experimental comparison between a monochromatic setup at 260 nm wavelength, which is for the disinfection treatment affecting microbe’s nucleic acids, and a polychromatic setup with five monochromatic light sources (250 nm, 260 nm, 270 nm, 280 nm and 300 nm), which adds a protein denaturation factor to the nucleic acid treatment, a three-time better performance of the monochromatic setup in comparison to the polychromatic setup was determined flow rate dependent. Interestingly, the combination of both setups led to an unexpected multiplication of Development of a modular ASI water reactor prototype for UV-C sterilization with LEDs and parametric TOC measurement the disinfection rate. A final analysis of UV-C LEDs as a radiation source for subproject (I) showed that despite considerable cost savings and significantly lower energy requirements, it is not an adequate replacement due to insufficient efficiency. But the acquired data could be transferred to the modular system (part III) and used to build an experimental UV module. (III) The third sub-project addresses the design, development and construction of a transportable and modular ASI water treatment system with functional module units (ASI - actuators, sensors, invors). The developed modules allow the simultaneous preparation and analysis of different water parameters of a single sample. Existing portable water analysis and treatment solutions often focus on only one of these two aspects or are limited in their parameters. The system not only serves to miniaturize experimental setups, but also generates new possibilities for experimental testing thanks to its unique structure. The system also facilitates assembly and disassembly, flexible arrangement and reusability of the integrated components. Each component, whether a sensor, actuator, or invor, is integrated into a low-cost 3D printed module. These modules feature a common design that provides standardized connections for water, power and signals, as well as protection from external influences. Their conceptual design allows for easy adaptation and integration of future developments, such as new measurement and cleaning elements, or electronic components. In the process of the project, a modifiable complete structure was realized, which includes several functional prototype modules for ASI components. These modules are designed for the measurement of temperature, conductivity, UV-C disinfection, filtration and signal- and water processing. The mobile, modular ASI system, due to its functionality and expandability, is relevant for laboratory experiments and a lot of different applications, like processing of various known or unknown and difficult to access waters, or for monitoring food production processes. In the research context it can be used for various experimental setups, one particular example is the use for the analytical of algae bioreactors. The experimental test series of the individual subprojects were carried out mainly with sucrose or the microorganisms E. coli and Saccharomyces c. The results showed that the subprojects have been successfully implemented and are operational. The application of the systems and the extension of the module chain with new methods and components is envisaged. This will open new fields of application