for their valuable input and support to my study, research, and life. Thanks to Associate Professor Vangelis Angelakis who showed me another methodology to conduct research. Special thanks to Professor Michael Hörnquist who genuinely helped me a lot to stay and to develop.Moreover, I would like to show my appreciation to my colleagues and partners within the projects I was involved, Ola Weister, Kahin Akram Hasv san, Professor Anita Lloyd Spetz, Docent Donatella Puglisi, Tomas Uusitalo, Åke Johansson, and Patrik Arven, for their trust and support. I sincerely thank the company of my dear colleagues and friends from the Chinese students and scholars association and in my life. I do enjoy the friendship and fun we had.Vinnova, Swedish Environmental Protection Agency, and Norrköping Fund for Research and Development in Sweden are acknowledged for financial support of the Ph.D. study.Last but not least, I want to express my deepest gratitude to my family, my wife Xinchen Wang, my parents and my parents in law. Without your firm support behind me, I could not have gone so far.