Two examples of thermal drying of sewage sludge

The increasing amount of sewage sludge, legal requirements and a change in the assessment of common disposal paths lead more and more to thermal drying of sewage sludge. During the last years a lot of sludge drying plants in Germany were planned, built and brought into service. This paper describes two different kinds of sludge drying plants with their determining and operating values, the costs and the reasons for the choice of the drying method. The examples given are the sludge drying plant at Darmstadt (2 lines with a 2 stage dryer) and in the surrounding area of Frankfurt (1 line with a drum dryer).