1. 1 June 1992 – 30 Nov 1992, Research Assistant, Environmental Technology, Central Laboratory, Finland
2. 1 Aug 1993 – 31 Jul 1995, Researcher, Laboratory of Inorganic and Analytical Chemistry, Aalto University, Finland
3. 1 Aug 1995 – 31 Jul 1998, Assistant, Laboratory of Inorganic and Analytical Chemistry, Aalto University, Finland
4. 1 Nov 1996 – 31 Aug 1997, Consultant, Nokia Mobile Phones, Finland
5. 26 May 1998 – 31 May 2000, Lecturer on Environmental Technology, Espoo-Vantaa Institute of Technology, Finland
6. 1 Aug 1998 – 31 Jul 1999, Research Scientist (post-doc), Laboratory of Environmental Protection Technology, Aalto University, Finland
7. 1 Aug 1999 – 23 Nov 2000, Research Scientist (post-doc) & Lecturer, Laboratory of Environmental Protection Technology, Aalto University, Finland
8. 1 Nov 1999 – 31 Dec 2000, Special Researcher, Technical Research Centre of Finland (VTT), Finland
9. 1 Oct. 1999 – 28 Feb 2001, Scientific Advisor, IP Engineering Ltd., Finland
10. 24 Nov 2000 – 31 Dec 2003, Professor, Laboratory of Water Resources and Environmental Engineering, University of Oulu, Finland
11. 2002, Scientific Advisor, Lassila & Tikanoja Ltd., Finland
12. 1 Aug 2003 – 31 Dec 2010, Professor, Laboratory of Applied Environmental Chemistry, University of Eastern Finland, Finland
13. 2004, Scientific Advisor, Tricol Oy Ltd., Finland
14. 2004, Scientific Advisor, Plancenter Ltd., Finland
15. 1 Jan 2005 – 31 Dec 2006, Lecturer on Environmental Technology, Mikkeli Polytechnics, Finland
16. 2005 – May 2018, Thesis Supervisor, Helsinki School of Economics, Finland
17. 2006 – 28 Jan, 2020, Consultant, Miktech Ltd./Miksei Ltd., Finland
18. 2008, Member of Board, Biower Ltd., Finland
19. 1 Oct 2008 – present, Adjunct Professor, Department of Biological and Environmental Science, University of Jyväskylä, Finland
20. 1 Nov 2008 – 31 Oct 2013, Adjunct Professor, Department of Civil and Environmental Engineering, Aalto University, Finland
21. 1 Nov 2009 – Oct 2014, Adjunct Professor, Aalto University, Finland
22. 15 Dec 2009 – 20 Jan 2010, Consultant, FCG Finnish Consulting Group, Finland
23. 1 May 2010 – 29 Nov 2019, Professor, LUT University, Finland
24. 1 Mar 2011 – April 2011, Adjunct Professor, LUT University, Finland
25. 1 Oct 2013 – Sep 2018, Member of Board, Luxhammar, Finland
26. 1 June – 31 July 2015, Consultant, Borenius, Finland
27. 1 Jul 2015 – 30 Jun 2018, Courtesy Professor, Department of Civil and Environmental Engineering, Florida International University, United States of America
28. 20 Mar 2020 – 31 May 2021, Visiting Researcher, Duy Tan University, Vietnam
29. 1 Jul 2020 – 30 Jun 2023, Professor, University of Electronic Science and Technology of China (UESTC), China
30. 1 Aug 2020 – 31 Jul 2021, Adjunct Professor, University of Nairobi, Kenya
31. 1 Dec 2020 – 30 Nov 2021, Researcher, Ton Duc Thang University, Vietnam
32. 1 Sep 2020 – present, Distinguished Visiting Professor, University of Johannesburg, South Africa
33. 1 May 2021 – 31 Dec 2023, Professor, Aarhus University, Denmark
34. 1 Jan 2021 – 31 Dec 2021, Distinguished Visiting Professor, National University of Malaysia, Malaysia
35. I Jan 2021 – 31 Dec 2022, Professor, Shoolini University, India
36. 1 Jan 2021 – 31 Dec 2022, Professor, King Saud University
37. 1 Jan2021 – 31 Dec 2022, Visiting Scientist, Abu Dhabi University, United Arab Emirates
38. 22 Nov 2021 – 21 Nov 2026, Director, Rongsheng Environment, China
39. 29 Apr 2021 – present, Visiting Professor, University of Novi Sad, Serbia
40. 1 Jan 2022 – 31 Dec 2023, Adjunct Professor, Persian Gulf University, Iran
41. 1 March 2022 – present, Visiting Professor, Chandigarh University, India
42. 1 Jun 2022 – 31 Dec 2022, Visiting Researcher, Duy Tan University, Vietnam
43. 1 Jun 2023 – present, Research Fellow, INTI International University, Malaysia
44. 1 Aug 2023 – present, Adjunct Faculty Member, Lovely Professional University, India
45. 1 Aug 2023 – 31 Jul 2025, Distinguished Faculty, UPES, India
46. 1 Sep 2023 - present, Adjunct Faculty Member, Saveetha School of Engineering, India
47. 1 Sep 2023 – 31 August 2026, Extraordinary Professor, University of Pretoria, South Africa
48. 1 Oct 2023 – 30 Sep 2024, Research Fellow, Lebanese American University, Lebanon
49. 8 Dec 2023 – 22 Oct 2024, Distinguished Professor, Woxsen University, India
50. 18 Dec 2023 – present, Adjunct Research Faculty, Chitkara University, India
51. 1 Jan 2024 – 31 Dec 2024, Research Fellow, Gulf University for Science and Technology, Kuwait
52. 1 April, 2024 – 31 March 2026, Adjunct Professor, Parul University, India
53. 1 Jan 2025 – present Visiting Researcher, Duy Tan University, Vietnam
54. 1 Mar 2025 – 29 Feb 2028, Professor Extraordinarius, University of South Africa, South Africa
55. 3 Mar 2025 – 3 Jul 2025, International Visiting Professor, Uniwersytet Marii Curie-Skłodowskiej w Lublinie, Poland
56. 17 Oct 2025 – present, Consultant, Huzhou Talent Group, China
57. 20 Oct 2025 - present, Consultant, Hangzhou Qianxun Human Resources Co, China
58. 18 Nov 2025 - present, Consultant, Qingfei Talent Technology, China
59. 24 June 2026 - present, Visiting Research Professor, Gulf University for Science and Technology, Kuwait