Advanced Techniques of Natural Dewatering of Sewage Sludge: An Innovative Solar Greenhouse for Enhanced Sewage Sludge Drying

The cost of treatment and disposal of sewage sludge is expected to increase in the near future, primarily due to the growth of the urban population, the improvement in the quality of human life, and the development of agriculture and industry. It is necessary to develop new sustainable and efficient solutions to reduce the weight of sewage sludge from wastewater, aiming for dehydration to increase the dry matter content and reduce the amount of water in the sludge leaving treatment plants, thereby decreasing transportation and disposal costs. Considering this, the present work illustrates the design, implementation, and experimentation of solar greenhouse prototypes based on the principle of thermal convection to achieve greater sludge drying. The experimental phase was conducted in three different seasons (winter-spring-summer) and with different plant configurations to maximize sludge drying performance. This study has shown that solar greenhouses with warm air insufflation perform better than conventional greenhouses. Moreover, better performance was achieved during the summer trials. The greenhouse that demonstrated the best performance allowed for a weight reduction of the sludge by approximately 98%. Therefore, it can be stated that these sludge drying systems significantly minimize the volume of sludge destined for landfills.