Disinfectants, such as chlorine, are widely used in water treatment plants to ensure the safety and quality of drinking water. However, these disinfectants easily react with some natural or man-made organic compounds in raw water and then form disinfection by-products (DBPs). For example, halogenated acetic acid (HAAs) and trihalomethanes (THMs) are two main components of DBPs. The purposes of this study are to analyze the concentration of DBPs including HAAs and THMs in drinking water and investigate the distribution of DBPs in the processes of three advanced water treatment plants in southern Taiwan. The analytical method of HAAs is based on the USEPA Method 552.3 and THMs is analyzed by headspace solid-phase microextraction(HS-SPME). Moreover, some factors which may influence the formation of DBPs such as dissolved organic carbon (DOC) and water temperature are also analyzed to further discuss the relation to the generation of DBPs. Through this study, the results could be the reference for operation control in water treatment plants and regulation setting in Taiwan. The samples of drinking water were collected in three advanced water treatment plants in southern Taiwan from June 2007 to April 2008. The analyzed HAA9 results were 28.71 ¡Ó 14.77£g g / L in Plant A, 24.43 ¡Ó 15.70 £g g / L in Plant B, 28.91 ¡Ó 14.38 £g g / L in Plant C. Comparing the HAA5 results with the maximum contaminant level (MCL) in USEPA, it was clearly found that all the values were under the standard of 60 £g g / L. As to THMs, the results were 9.99 ¡Ó 3.39£g g / L in Plant A, 0.94 ¡Ó 2.12 £g g / L in Plant B, 28.91 ¡Ó 14.38 £g g / L in Plant C and greatly under the EPA standard of 80 £g g / L in Taiwan. Furthermore, the major species of HAA9 in order were BCAA and TCAA while THMs was trichloromethane (CHCl3). In the relation between DOC and DBPs, the results demonstrated that DOC was more relative to DBPs in raw water; meanwhile, the water temperature did not show great relation. In general, despite the poor correlation, it was still could conclude that the concentration of DBPs increases with the increase of DOC and temperature. In conclusion, the research results showed that the removal efficiency of DBPs in Plant A and B (UF/RO system) is greater than Plant C (Biological Activated Carbon system, BAC system ), and all three advanced water treatment plants could show greatly effectiveness in drinking water quality improvement. However, higher concentration of bromine products in HAAs was discovered in this research. It was suggested that the phenomenon should be further discussed and controlled.

The gas turbines in the Swedish secondary reserve are reaching the end of their technical lifetime, hence alternative solutions need to be considered. One of the solutions thought to have the greatest potential is the use of so called consumptionreduction. By entering contracts with large consumers, agreements are made to reduce consumption in the event of major disturbances in the power system and thus being used as a secondary reserve. This thesis investigates the feasibility of consumption reduction as part of the secondary reserve. This has been achieved by developing a requirement specification for the disturbance reserve and by studying the technical and economic potential for consumption reduction among a range of consumers.The technical potential for consumption reduction that fulfils the requirements for participating in the secondary reserve are on average 750 MW in SE 3 and 98 MW in SE 4. The result of this study shows that consumption reduction could work as a supplement to the gas turbines, but could not entirely replace the current solution. Furthermore, replacing the gas turbines would cause loss of features such as black start and automatic frequency regulation. Nevertheless, consumption reduction is considered as a workable solution for the disturbance reserve that is both cheaper and more environmentally friendly. Before launching consumption reduction as a reserve, a market model has to be developed, taking the findings of this thesis into account: high electricity prices have negative effect on availability and that low liquidity on the market causes short endurance.

This dissertation studies three economic problems plagued by multiple equilibria. Indeterminacy of equilibrium outcome often poses a challenge in deriving robust predictions and policy guidance. The dissertation shows how the utilization of potential game theory can better deal with this challenge. Chapter 1 studies a general contracting problem between one principal and multiple agents. The interdependence of agents’ actions and payoffs creates a coordination problem among them, leading to multiple equilibria. In general, the principal’s optimal contracting scheme varies with how one selects among equilibria. Nevertheless, for a large class of contracting models where agents’ payoffs constitute a weighted potential game, I show that one contracting scheme is optimal for a large class of equilibrium selection criteria. This scheme ranks agents in increasing weight in the weighted potential game and induces them to accept their offers in a dominance-solvable way, starting from the first agent. I also apply the general results to networks and pure/impure public goods/bads. Chapter 2 studies two-sided markets, where two groups of agents interact via platforms. These markets exhibit network effects, i.e., the value of joining a platform increases with the number of users, which in turn lead to multiple equilibria. I show that many two-sided market models are weighted potential games, enabling the selection among equilibria by potential maximization—a refinement of Nash equilibrium justified by many theoretical and experimental studies. Under potential maximization, platforms often charge the side deriving more network benefits and subsidize the other side. Therefore, profit-maximizing platforms are often designed to favor the money side much more than the subsidy side. Chapter 3 studies markets with strong network effects. In these markets, firms compete for the adoption of all consumers rather than the marginal consumer. Therefore, the Spence distortion—a quality distortion driven by competition for the marginal consumer—should be absent, contradicting the findings in the network economics literature. This inconsistency stems from the choice of equilibrium selection criterion. I show that all popular selection criteria in that literature lead to Spence distortions, whereas potential maximization does not. Therefore, network market regulations based on Spence distortion arguments may be misguided.

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