Potential use of sewage sludge as fertilizer in organic farming

Abstract

The management and disposal of excess sludge remain critical challenges, primarily due to the high costs involved in its treatment. Treated sewage sludge, derived from wastewater treatment plants (WWTPs), is increasingly recognized as a resource for agricultural use, given its nutrient-rich composition, including nitrogen, phosphorus, potassium, and essential micronutrients required for plant growth. This review article outlines the state of research on the use of sewer sludge as a fertilizer in organic farming, its potential negative effects on soil fertility, moisture retention, and stimulating microbial activity. While these benefits are well-documented, concerns surrounding heavy metal contamination, microbial risks, improper application techniques, and regulatory challenges must be addressed to ensure safe and effective use. Furthermore, this review consolidates findings on various sludge treatment methods, including thermal treatment, anaerobic digestion, and composting, which aim to optimize its agricultural benefits while minimizing associated risks. By synthesizing recent advancements and challenges, this review provides insights into the integrated management of sewage sludge and highlights its implications for sustainable farming practices and ecosystem health.