The rapidly evolving environmental awareness and strict legislations in different countries have focused research towards the use of alternative fuels and also promoting sustainable biorefinery by utilizing waste materials as substrates. In general, the biodegradable wastes are identified as sources for high value-added compound recovery in framing the circular bioeconomy model. It is therefore noteworthy to mention that energy has become a crucial factor for humanity to continue the economic growth and social development, and maintain high living standard especially after the inauguration of the industrial revolution in the late eighteenth and early nineteenth century in both the developing and developed economies. With the global population swelling and industrialization is on the rise in many countries, humanity’s hunger for energy has reached unprecedented levels. However, much of the world’s energy is produced and consumed in ways that are not eco-friendly and environmentally sustainable. Moreover, more than half of our energy comes from fossil fuels that are extracted from deep within the Earth’s crust. As fossil fuels are depleting day by day, there is a need to find out alternative renewable fuels to fulfill the energy demand of the world. More importantly, several major industries are currently looking to reduce their dependence on fossil fuels and shift towards renewable energies systems. The manufacturing sector plays very important role for growth. Simultaneously, it also causes severe environmental problems. Water pollution is one of the major problems caused due to industrial growth. The accidental release of many chemicals by industrial process into the water bodies has been reported globally. As a result of this, the dissolved oxygen content of surface waters decreases, which threatens both the flora and fauna. It also poses negative effects on human lifestyles and the natural ecosystem. It has adverse impacts on the food chains. In most of the countries, there are several rules and regulations to control water pollution. The polluter pays principle setup life as principle of economics. However, the cost to treat the waste water is normally higher than its final selling price in many countries. Hence, government funding is required to support this type of policy approach. To regulate water pollution by industrial activities, in different countries, there are various policy instruments having different names such as environmental tax, pollution permits, water pricing, and industrial parks which act in and provide joint efforts to identify and monitor the polluters. This approaches would help to move towards promoting the sustainable development.

On the other hand, rapid urbanization and industrial developments are the most crucial tool for the exploitation and pollution of the freshwater resources. Changes in climate and landscape utilization pattern are the serious concern for urban water ecosystems and for mankind. Increase in hard surface area, generation and mismanagement of wastewater, flooding, greenhouse gas emission, and many other factors are seriously destroying the freshwater resources in both qualitatively and quantitatively manners. Increase in temperature and other human activities are also key factors for water pollution and reduce the availability and utilization of water resources. Due to abovementioned factors, limited water availability and huge water demand becomes a serious challenge for urban planners and governing bodies. Recently, much research has been devoted to conducting field studies and developing new tools to simulate the impact of climate change and anthropogenic activities on aquatic environments, in order to understand the complex dynamics under different conditions. But keeping in mind the significant importance of water resources for mankind, it is still required to conduct the research on all the aspects of impact of climate change and anthropogenic activities, eutrophication, biogeochemical cycles, emerging pollutants in water environment, and flood resilience. Therefore, applied research and implementation of various water treatment facilities and technologies are the need of the day for protection and management of precious water resources.

The special issue covers the various advancement of research and innovations in the field of wastewater treatment and enhanced recovery of value added products from solid, liquid, and gaseous wastes. Specific topics covered in this include, among others, drought propagation to watershed scales, erosion characteristics of sandstone slopes, the applications of functionalized activated carbon, biofuel and its applications, treatment systems for drinking water, sustainable electricity management, and biochemical methane/energy potential from wastes. The guest editors of this special issue are thankful to the Editor-in-Chief of Environmental Science and Pollution Research (ESPR), Professor Philippe Garrigues for providing an opportunity to publish selected peer-reviewed papers that were presented at ICAFEE-ICWRS2018. Our special thanks to Ms. Fanny Creusot and Ms. Florence Delavaud, Editorial Assistants of ESPR and the entire production team at Springer for their valuable support in bringing out this issue successfully. We also thank all the reviewers for providing critical reviews, comments, and feedback on manuscripts that were submitted for this thematic special issue. On a personal note, the guest editors would like to thank Prof. Dafang Fu (Southeast University, China), Prof. Chris Zevenbergen (IHE Delft, The Netherlands), and Prof. Willium F. Hunt, III (North Carolina State University, USA) for chairing the ICAFEE/ICWRS 2018 event. We are grateful to acknowledge the efforts of our advisory scientific and organizing committee members for their untiring efforts to make the conference a grand success. We would like to thank all participants and authors for their hard work that have yielded this special issue a unique success. We firmly believe that you will enjoy reading the manuscripts presented in this special issue and also share the issue with your research team.