Biosolids: The Trojan horse or the beautiful Helen for soil fertilization?

The simultaneous requirement to manage resources and wastes in more rational way has meant that many communities worldwide have begun to search for long-term alternative solutions. Reuse and recovery of biosolids is considered to be a constant solution of circular sustainability, as waste disposal without further reuse background like fertilizer is no longer an alternative to be promoted. There have been developed many treatment methods over the years for the stabilization and sanitization of biosolids. However, the literature concludes that none of them is fully integrated by meeting all the basic criteria. Each method has its Achilles heel, and the appropriateness of the method lies in what is the goal each time. There are conventional methods with positive reciprocity in terms of sustainability, reuse indicators and technological maturity, but have high risk of microorganisms' reappearance. New advanced sustainable technologies, such as cold plasma, need to be further studied to apply on a large scale. The reuse of biosolids as construction materials is also discussed in the context of circular economy. Biosolids reuse and management legislation frame need to be revised, as a directive adopted 30 years ago does not fully meet communities' current needs.