Due to the rapid increase in the world population in recent years, the demand for resources such as food and energy has increased. As a result, the amount of waste production and the level of pollution caused by it has increased greatly. In order to protect the environment, the increase of waste and its burial must be prevented with new methods. Currently, most organic solid waste is either land-applied or sent to landfills, with the remainder incinerated or anaerobically digested. However, with the current emphasis on emission reduction, nutrient recycling, clean energy production and circular economy, rethinking some of the conventional methods of treating these wastes and exploiting their largely unrealized potential in terms of environmental benefits and Economy is important. . Sewage sludge, with its high organic content and relatively constant supply, provides an excellent opportunity to implement some of these strategies using thermochemical conversion technologies, which are considered as one of the alternatives for recycling such waste streams. This paper summarizes the results of outstanding studies for the valorization of sewage sludge through thermochemical conversion technologies while drawing conclusions and identifying the relationships between the various technical and operational parameters involved. This is followed by sections emphasizing the environmental and economic implications of these technologies, and their related products, in the broader contexts of waste-to-energy, nutrient recycling and progress towards a circular economy.

House treatment, energy, Activated sludge, garbage, environment, circular economy