Sustainable sewage treatment for 21st century

In 2015, in total 2.4 billion people still use unimproved sanitation facilities, including 946 million people who still practice open defecation. On the other hand, in most developed countries, close to 100% of sewage produced is being treated by intensive processes that deliver high quality effluents while being extremely costly and energy intensive. New sanitation concepts, acceptable both in developed and developing countries must be proposed to improve this situation. This paper shows some of the recent developments in sustainable sewage treatment that include resource recovery, less energy intensive techniques and decentralized solutions.