It is worldwide recognized that huge quantities of waste materials still end up in landfills. In a period of time that environmental awareness becomes more important, emphasis should be drawn on waste prevention and the promotion of reuse, recycling and energy recovery from waste minimizing landfilling. Even more, the current tendency is to move towards new products and chemical building blocks of high value derived from the generated waste offering new options and opportunities at technological level to address modern societies. Policies and strategies should also contribute towards this direction. At European level, the symbiosis concept and the need to promote circular economy and resource efficiency will influence without any doubt all quantitative targets of the Waste Framework Directive in the near future, being a strong tool to improve the current consumption patterns and the existing waste management status. This Special Issue entitled: ‘‘Waste Management and Valorization’’ includes the best papers selected from two conferences, namely, the TINOS2015 3rd International Conference on Sustainable Solid Waste Management (http://www.tinos2015.uest.gr) held in Tinos Island, Greece, 2nd–4th July 2015 and the IWWATV 2015 International Conference on Industrial Waste and Wastewater Treatment and Valorization (http://www. iwwatv.uest.gr) held in Athens, Greece, 21st–23rd May 2015. Following the ATHENS 2012 and the ATHENS 2014 International Conferences, the TINOS 2015, the third conference of the series, aimed to address the significant issues for sustainable solid waste management through the promotion of effective technologies and success practices, stimulating the interest of scientific community, competent authorities and public on the latest developments in the specific field. Biological Treatment (composting and anaerobic digestion), the treatment at central facilities, waste prevention and separation at source with emphasis on biowaste also constituted priority subjects of the rich conference agenda. Special attention was drawn on sustainable waste management for areas with specific characteristics, such as islands and generally isolated areas, while the success of the conference was evident by the number of participants, the participating countries and the quality of the papers presented. The Conference provided an opportunity to bring together scientists and professionals from government departments, Municipalities, private institutions, research and education institutions, being a forum for the exchange of the most recent ideas, techniques and experiences in all areas of municipal solid waste management. Last but not the least, the intention of the Conference was to promote further the European Commission policies for effective waste management. The Conference was organized within the LIFE ? ISWM-TINOS project (LIFE10 ENV/GR/ 000610) (http://iswm-tinos.uest.gr) dealing with the implementation of an integrated solid waste management scheme for islands. Furthermore, after the SYMBIOSIS 2014 International Conference that was organized in June 2014, the IWWATV 2015 Conference gave emphasis on industrial & Maria Loizidou mloiz@chemeng.ntua.gr