Sludge Management: Integrating the Principle of Circular Economy into the Concept of Sustainability

The development of sustainable sludge management systems requires looking at them with a new vision in which the concepts of SD (Sustainable Development) must integrate those of CE (Circular Economy), both concepts subject to the principles of TD (Thermodynamics), thus allowing the adoption of actions that are all the more effective the more complete the evaluation of the social dimension has been. This involves a new “Way of thinking” which sees the sludge system as the “Locomotive” of the entire wastewater/sludge treatment train and is developed through “Ways of acting” which includes both “Technical” actions to maximize recoveries of useful materials and/or or energy, and “Socio/Institutional” actions to overcome barriers linked to local cultures and traditions, also considering that the specific local context heavily influences the choices capable of satisfying the concepts of CE. It follows the need of issuing realistic and applicable regulations and overcoming social barriers, such as lack of infrastructure and/or qualified personnel, to achieve an effective integration of the concepts of CE with the more general ones of sustainability.