Bjoern de Haan, BACKHUS North America

CONCLUSIONDrying of sewage sludge with a DM of 18% without adding structure material is even possible under winterweather conditions. However the demand of time to achieve a temperature of 122 F is almost doublecompared to summer conditions.The adding of fresh sludge at frequent intervals of seven to ten days to windrows with a temperature ofmore than 105 F is possible without having interruptions in the drying process.The adding of smaller amounts of sludge does not have any better influence on the process. We found thatthat the process with an adding of a bigger amounts once per weeks brings the best result.With continuous adding of fresh sludge during drying process the specific drying result can be upto 15% better compared to a process without adding.