RESEARCH ON PROCESS CONTROL OF CERAMSITE PREPARATION FROM URBAN SEWAGE TREATMENT PLANT SLUDGE AND DIFFERENT STRAWS

Background and Purpose: Urban sewage sludge and agricultural straw are produced in large quantities and pose significant disposal challenges. Converting these wastes into value-added materials is crucial for promoting sustainable waste management and circular economy development. This study aims to explore the feasibility of producing ceramsite from urban sewage sludge and different types of straw, and to evaluate its water absorption characteristics and cadmium adsorption performance for potential environmental remediation applications. Methods: Sewage sludge was used as the primary raw material, supplemented with clay and mixed separately with sugarcane bagasse powder, rice straw powder, and corn straw powder. The mixtures were calcined at 800°C and 900°C to prepare ceramsite with varying sludge proportions. Water absorption rates were measured, and batch adsorption experiments were conducted to assess the removal efficiency of heavy metal cadmium under different preparation and dosage conditions. Results: Among the tested materials, rice straw-sludge ceramsite exhibited the highest water absorption capacity. Increasing the sludge content led to a notable decrease in water absorption, while ceramsite calcined at 800°C showed slightly better performance than that produced at 900°C. At a dosage of 0.5g, the ceramsite nearly achieved complete cadmium removal. Moreover, the cadmium adsorption efficiency of rice straw-sludge ceramsite remained stable and was not significantly affected by calcination temperature or sludge ratio. Conclusion: This study demonstrates that sludge-straw ceramsite, particularly rice straw-sludge ceramsite, is an effective adsorbent for cadmium removal and a viable pathway for the resource utilization of urban sludge and agricultural residues, supporting environmental protection and circular economy development.