Mika Sillanpää is a professor at the University of Johannesburg, South Africa. His research centers on chemical treatment in environmental engineering, environmental monitoring, and resource recovery from waste streams. Sillanpää received his M.Sc. (Eng.) and D.Sc. (Eng.) degrees from the Aalto University where he also completed an MBA degree in 2013. Since 2000, he has been a full professor/adjunct professor at the University of Oulu, the University of Eastern Finland, the LUT University, the University of Eastern Finland and the University of Johannesburg. He has received numerous awards for research and innovation. He is the first Laureate of Scientific Committee on the Problems of the Environment (SCOPE)'s Young Investigator Award, which was delivered at the UNESCO Conference in Shanghai 2010 for his "significant contributions, outstanding achievements and research leadership in Environmental Technological Innovations to address present water pollution problems worldwide, especially with regard to wastewater treatment and reuse. In 2011, he was invited to act as a Principal Scientific Reviewer in the GEO-5 report of the United Nations Environmental Programme (UNEP). In 2012, he received Tapani Järvinen Environmental Technology Award and Publication Award of the Lappeenranta University of Technology. In 2014, he received the Science Award of the Lappeenranta University of Technology and Pro Mikkeli Award. In 2018, he was invited as a Member of the Finnish Academy of Sciences and Letters and Technology Academy of Finland. He also received Literature award from the Water Association of Finland in 2018.Dr. Chaker Ncibi obtained his PhD in Environmental Engineering in 2008 from the University of Sousse, Tunisia. He pursued his research activities as postdoctoral researcher in France, Guadeloupe, Germany and Finland. Currently, he is Assistant Professor in 'circular economy in water treatment' at the Department of Green Chemistry, School of Engineering Science, Lappeenranta University of Technology, Finland. His teaching and R&D focus areas include circular economy, bioeconomy, sustainability, green chemistry, advanced water and wastewater treatment technologies (adsorption, membrane bioreactor, AOPs and electrochemical processes), resources recovery from municipal and industrial side streams, and the thermochemical conversion of biomass and biowaste into materials, fuels and chemicals. Dr. Ncibi is the principal investigator of many projects, guest editor for several special issues in Elsevier journals, and has published more than 50 peer-reviewed articles and two books in the broad field of sustainability.