| In recent years, with the slightly polluted source water emerging, it is difficult for the conventional drinking water treatment processes to meet the increasingly stringent standards for drinking water quality, therefore hunting for new drinking water treatment processes or some combined processes become a hot topic in the field of water research.Firstly, it was discussed on the occurrence and fate of these organic pollutants in two important water sources and conventional water treatment processes in Harbin, then the previous studies on lab scale involving emerging water treatment process are explored, including the heterogeneous catalytic ozonation process with zinc silicate as catalyst, the heterogeneous catalytic ozonation with zinc silicate and hydrogen peroxide as catalyst, and biological activated carbon-membrane combined processes. In this paper, the application of the advanced oxidation process in water supply to remove organic contamination was investigated in depth, which will provide data support for the further step; on the other hand, it was discussed for the advanced drinking water combined processes on the basis of mechanism such as chemical oxidation by ozone, adsorption by biological activated carbon, and physical screening by membrane, which also highlight the transformation of advanced treatment techniques for different water sources and idea of advanced system application for household. Specific results are as follows,42trace organic pollutants (TrOCs) wereselected, and the investigation was carried out in two important water sources of Harbin (M and S) in the view of temporal and spatial study. It was found that six phthalate esters, ten polycyclic aromatic hydrocarbons and six currently used pesticides got higher detection rates with the concentrations at ng~μg/L level, in which case, the spatial and temporal distribution characteristics of the TrOCs varied, and they became the important source for the contaminants in water samples during the conventional drinking water (coagulation, sedimentation and filtration). Although various water qualities has a certain impact on the results, the TrOCs studied in this thesis were still found to get high detection rates with monitoring the water samples from the conventional water treatment process, which revealed poor removal efficiency of organic pollution by water treatment process. As a result, there may be a threat to human health. On the basis of previous studies on lab scale, three-level reactor for differentcatalytic ozonation systems was established. Firstly, optimum running conditions for advanced drinking water treatment processes are as follows: the ozone ratio of one-level is0.8~1.0, and the contact time of three-level is10~15min. In that case, the single ozonation system had some impact on organic matter removal, and the removal efficiency of UV254became the highest result, which can be used as a fundamental organic performance indicator for the system investigation. There were some effects on the organic matter removal such as: temperature, water matrix, liquid flow and dosing method. The catalyst zinc silicate had a better catalytic performance in the static experiments, thus, its effect in a heterogeneous ozonation system for long-running condition needs to be discussed. It was found that the application of this system can significantly improve the organic removal efficiency, and even at the ratio of0.7~0.8after reducing the value, the process still got the same performance in the best situation. In addition, the zinc silicate catalytic ozonation system was less affected by the dosing methods, but more by the temperature. Moreover, O3/zinc silicate process showed better results on disinfection byproduct precursors and fluorescence DOM than that of the single ozonation system. With the traditional BAC process combined, the system highlighted the synergy, which could provide a better solution in the case that the poor nutrient and low-temperature water are not appropriate for the BAC process. The removal performance of different types of TrOCs in water by the heterogeneous catalytic system was investigated, and the results showed that the system got significantly higher removal rates for some TrOCs involving higher reaction rate constant with·OH. Meanwhile, removal efficiencies of PAEs and CUPs by the system were higher than those of PAHs in the waters.Both the lab static and pilot scale experiments were carried out, in which the optimum running condition was determined. When the molar ratio of O3and H2O2is closed in0.5~0.6, the system could improve the removal efficiencies of DOC, CODMn and UV254; Moreover, with adding the catalyst zinc silicate to O3/H2O2system, it was the first time to find out that the heterogeneous catalytic ozonation in practical application may significantly promote the degradation of the bulk organic matter and detectable TrOCs in water, which will provide data support to the following studies in heterogeneous catalytic ozonation mechanism.Two typical optimized combination processes of biological activated carbon and membrane (BAC-UF and PAC-SUF) were done to compare the characteristics of start-up and organic matter removal at the condition of low temperature and poor nutrient intake. The results showed that a mechanism involving the degradation of biological activated carbon and physical screening of membrane was built and the synergism was powerful. The time of start-up for these two systems was much longer. After this period, PAC-SUF had better removal efficiency than the one of BAC-UF. There is some effect for BAC-UF such as EBCT, carbon layer depth, aeration method and temperature, and both extending EBCT≥20min and elevating the water temperature using heat exchangers were fine for pollution removal in winter when the performance of BAC was down. PAC-SUF was skilled in AOC and fluorescent DOM removal, while BAC-UF was expert in THMFP removal. In general, the two combine processes had the ability to control the concentration of TrOCs in waters, but the removal rates were lower than those for the catalytic ozonation processes.On the whole, the advanced oxidation-biological adsorption-membrane treatment processes did promote the removal efficiencies of organic matter, especially the one of TrOCs in water. The combination involving three barred mechanisms was the best solution, and it can provide the highest quality water for the water supply; at the point of the concept EE/O, the energy efficiency of catalytic ozonation was higher than those of the single ozoantion process. |
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