Analysis of the fertilizing potential of sewage sludge and its impact onagriculture and the environment

Purpose: The management of sewage sludge represents a major environmental challenge on a global scale, as poor management can lead to significant risks for public health and the environment. This study aims to assess the fertilizing potential of sludge and its impact on agriculture and the environment, offering a sustainable solution for recovering this waste while improving soil fertility. Method: First, a physico-chemical study was carried out to identify the nutrients and organic and metallic pollutants present in the sludge analysed. Subsequently, the potential of this sludge as an organic fertilizer was evaluated. The impact of sludge application was studied on plants, with a quantification of heavy metals in the aerial and root tissues of the inoculated plants. Result: The sludge analyzed contains high organic matter (85.57%) and moisture (53.67%), making it ideal as a soil improver to enhance structure and water retention. Rich in phosphorus (71%), it supports plant growth. Organic and metallic micropollutants are present only at trace levels, well below AFNOR limits. Sludge application promotes heavy metal absorption by plants, with accumulation in aerial parts and soil. It also boosts plant dry biomass in aerial and root tissues, while heavy metal levels in plant tissues remain within regulatory thresholds. Conclusion: These promising results allow recommendations to be considered for promoting increased use of sludge in agriculture to improve yields. Integrating sludge recovery into a circular bioeconomy approach not only helps to reduce the amount of sludge generated, but also to limit their environmental impact. Research Highlights • Sludge improves soil fertility by providing essential organic matter and nutrients. • Sludge adds organic matter to the soil, improving its structure and biological activity. • Sludge reduces the need for chemical fertilizers and reduces waste • Sludge improves nutrient recycling, which enhances agricultural sustainability. • Sludge recovery reduces the carbon footprint by reducing emissions from chemical fertilizers. • Proper management and treatment are necessary to avoid the risk of contamination.