Continuous Monitoring and Process Optimization of Sludge Inertization: A Sustainable Approach at the SIR SPA Plant

The stabilization and solidification (S/S) of sludge is a widely adopted method for reducing the environmental risks of hazardous waste. However, real-time monitoring systems for controlling such processes remain underdeveloped. This study presents the design, implementation, and validation of a continuous monitoring system for the inertization of sludge at the SIR SPA plant, integrating real-time sensors and a data-driven process control algorithm. The monitoring framework incorporates advanced automated probes designed to measure oxygen concentration, water content, temperature, and pH levels directly within treated sludge. During a five-month campaign, the system collected more than 10,000 individual readings. These data were utilized to create a predictive algorithm for anomaly detection and process optimization, enabling remote monitoring of sludge quality and system performance. The results revealed a strong correlation between key parameters--oxygen, water content, and temperature (R > 0.85)--while pH levels remained consistently stable. The alert system demonstrated exceptional accuracy, identifying deviations from expected values with over 95% reliability. Moreover, the system proved highly robust under industrial conditions, with no probe failures or data losses reported throughout the monitoring period. However, the current system is primarily focused on measuring physical-chemical parameters. Future enhancements will include integration with leaching and ecotoxicological tests to strengthen compliance assessment. Despite this limitation, the developed system offers a scalable and cost-efficient solution for real-time monitoring of stabilization/solidification (S/S) processes in sludge treatment. This study presents an innovative, field-tested digital monitoring approach that addresses a critical technological gap in waste management. By enhancing operational safety, supporting adherence to EU regulations, and promoting sustainable industrial sludge management, the system demonstrates its significant practical and environmental value.