Sludge Drying after Flue Gas Cleaning

A company in Switzerland generates 1,200 tons of hydroxide sludge annually from flue gas cleaning and fly ash scrubbing. After mechanical dewatering in a fully automatic membrane filter press, the sludge has a dry solids content of 28% – 32%. In this case, the sludge drying was implemented as a container version. This consists of 4 drying containers and a Drymex^® dehumidification module. The drying containers, which usually also function as transport containers, have a usable volume of 22 m³ in this case. The Drymex^® dehumidification module achieves a water extraction rate of 200 – 240 liters per hour. The respective container is moved under the elevated press, filled in several intervals, and then taken to the drying station. At a temperature of 40° – 45°C, the sludge remains in the dryer for 48 hours. This time was chosen by the customer for logistical reasons. The dry solids content achieved is 85%. Between 8,000 and 12,000 liters of water are extracted during drying. The waste incinerator uses the 4 containers in rotation for its press, for drying, and for transport to and from the recycler. Negotiations are currently underway with the disposal company regarding the possibilities of recycling the valuable materials now released in the dried sludge.
You can find more information on this subject in our technical report.