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Aluminum salts are used as the primary coagulants in the majority of United States drinking water treatment plants. Despite decades of practical experience, there are important knowledge gaps regarding the effects of residual Al on distribution system materials as well as specific types of solids formed. The first phase of this work examined the formation of aluminosilicate deposits in copper and lead pipes using water from Denver, Colorado. It was anticipated was that these deposits could form barrier films on the pipe, protecting it from corrosion. However, the deposits had slightly detrimental effects on leaching of metal to water, and higher levels of aluminosilicates could further worsen corrosion by-product release. The second phase of work attempted to extend understanding of aluminum solubility controls by accounting for effects of sulfate and formation of solids other than Al(OH)₃ during water treatment. Sulfate was found to destabilize small Al(OH)₃ colloids resulting in agglomeration into larger flocs from pH 5.0-6.2 . At pH 9.0 and above, Al-Mg, Al-Mg-Si and Al-Si solids were discovered to control Al solubility, while also having significant impacts on the precipitation of calcite in the presence of silica and overall softening effectiveness. This could be of considerable importance to water treatment practice. These solids also had some potential for removal of arsenic, TOC and boron. / Master of Science

This diploma thesis builds on my bachelor thesis, which was focused on the application of low-pressure hydrogen plasma and argon-hydrogen plasma on layers of corrosion products. According to results of the experiments, an appropriate temperature for plasma chemical treatment of lead samples was detected. However, the process of corrosion removal through plasma chemical treatment needs to be further optimized to prevent potential damage to the original historical artefacts. Optimization of the treatment process is therefore the main subject of this work’s research. The model samples with artificial corrosion layers with dual composition were prepared. These samples were put to desiccator with sand and organic acid. The samples corroded in environment of acetic acid or formic acid with the aim of creating the corrosion, which would be at least partially simulated with corrosion on the original artefacts. The process of corrosion lasted for eleven months. After that, the samples were dried out under reduced pressure, put to the protecting foil with humid and oxygen absorbers. In contrast with my bachelor thesis where the continuous regime was chosen for the treatment, the pulse regime with three different condition settings is used. Process of experiment was monitored by OES, surface of samples was analyzed by SEM, EDX, XRD methods. Results from experiments with model samples were used for treatment of original artefacts with missing documentation, so their eventual damaging was acceptable.

This project uses CFD analysis to make design choices for a facility to test flow accelerated lead corrosion erosion of steel samples. Two conceptual designs are considered and compared through mechanical and physical criteria. The first design uses steel samples on stationary plates next to rotating discs. The second design has the steel samples on the rotating disc. The first design is considered unfeasible due to high pressure gradients in the system and a high power requirement from the motor. The second design removes the issue of high pressure gradients and can decrease the motor requirements. This design is selected for further analysis and discussion of manufacturing. / Detta projekt använder CFD-analys för att göra designval för en anläggning för att testa flödesaccelererad blykorrosionserosion av stålprover. Två konceptuella konstruktioner beaktas och jämförs genom mekaniska och fysiska kriterier. Den första designen använder stålprover på stationära plattor bredvid roterande skivor. Den andra designen har stålproverna på den roterande skivan. Den första konstruktionen anses vara ogenomförbar på grund av höga tryckgradienter i systemet och ett högt effektbehov från motorn. Den andra designen tar bort problemet med höga tryckgradienter och kan minska motorkraven. Denna design är vald för vidare analys och diskussion om tillverkning.