Environmental, Economic, and Ethical Assessment of the Treated Wastewater and Sewage Sludge Valorization in Agriculture

Sewage sludge is a by-product of the sewage treatment plants. Because of its richness in nutrients and for several environmental and economic reasons, this waste by-product is widely used as a fertilizer for agricultural purposes under specific conditions. This practice might be hazardous since this waste includes many known and unknown non-biodegradable and harmful pollutants, especially emerging organic contaminants (EOCs), as well as cultivable and non-cultivable pathogens. The present work is aiming at (1) providing information on the nature of sludge in terms of persistent pollutants and cultivable and non-cultivable microbiota generated by the currently implemented treatment processes, (2) analyzing the consequences of the agricultural valorization on ecosystem biodiversity and soil fertility, and (3) addressing and discussing the economic, ethical, and environmental benefits or damage of this type of valorization. These issues need full consideration by policy makers regarding the agricultural use of this waste by-product in terms of irrigation with treated domestic wastewater or sludge land spreading as soil fertilizer and plant growth promoter.