Abstract
Currently, sewage sludge management is a huge challenge in the field of environmental engineering. New effective solutions for the treatment of wastewater led to an improvement of the quality of the final effluent but considerably increased the volume of produced sewage sludge, which increases each year. Two points of view conflict regarding the recycling of those “wastes.” Primarily, dehydrated sewage sludge is considered a reservoir of nutrients and organic matter that can be used as a fertilizer in agriculture or as an organic amendment in the remediation of contaminated sites or to build “anthroposoils.” On the other hand, recycled sewage sludge is seen as a potential source of soil contamination by organic and inorganic pollutants and pathogens; potentially toxic elements (such as zinc, copper, cadmium, lead, silver, etc.); polycyclic aromatic hydrocarbons (PAH); polychlorobiphenyls (PCB); biocides and phytopharmaceuticals; pharmaceuticals, personal care products (PPCP), and residuals; synthetic hormones; microplastics; nanotechnology life cycle end products; and microorganisms such as Escherichia coli O157:H7 or Salmonella typhimurium. This chapter will focus on these aspects, highlighting the health and ecotoxicological risks associated with the presence of such contaminants in sludge. The environmental dangers of sludge spreading on soils will be presented as well as their possible treatment scenarios to propose an acceptable reuse of sewage sludge in a circular economy.