Assessing the Eco-Sustainability of Sewage Sludge Management

Sludge management has become one the most challenging issues for wastewater treatment plants, especially due to strict regulations for its reuse or disposal. Indeed, on one hand, the practices commonly used for sewage sludge management are no longer readily acceptable, on the other hand, new policies need to present affordable standards. At the same time, unlocking the potential of sewage sludge is recognized as a way to improve circular economy and sustainability of wastewater sector, as promoted by the European Green Deal. For these reasons, both the industrial and academic communities are investigating new solutions to improve the sustainability of sludge treatment. In this context, assessing the environmental and economic sustainability of sludge management is fundamental to compare different strategies. The pertinent available literature on sludge management proposes indicators that take into account: - specific aspects, such as production, reuse or treatment/disposal costs; - different categories of environmental impact through the methodology of life cycle assessment. This work aims at defining a comprehensive and intuitive assessment method that allows taking into account both the economic and the environmental impact of sludge management. A benchmarking of the most common practices for sludge management as well as of virtuous case studies proposed in the literature is carried out in order to identify different classes of environmental and economic sustainability that could be used to assess different scenarios. The proposed assessment method is finally demonstrated by applying it to a case study.