Drying has become an important step within the context of sludge management. Sometimes, sludges from several wastewater treatment plants are centralized in order to dry them at an acceptable cost. Depending on sludge supply, there can be a delay between delivery and feeding into the dryer. The impact of sludge storage duration on the drying kinetics and on the exhaust emissions of volatile organic compounds (VOCs), and ammonia is investigated. Results show that, after 20 days of storage, the drying time is multiplied by 1.5, and the emissions of VOCs and NH 3 are multiplied by 5 and 40, respectively.

Drying appears as a major step prior to valorization of sludge from a wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage, and extrusion. This research is performed with an industrial view, but on a single cylinder sample, and focuses on five factors: maximum drying flux, time to reach 95% of dry matter, final volume, critical moisture, and slowingdown coefficient.