Investigation of drying parameters of municipal wastewater sludge

Today, the population is increased day by day and also the throw waste in to the nature.In order to prevent the increase in the level of pollution seen on earth, human beings take various measures. Therefore, the number of wastewater treatment plants increases rapidly in parallel with the population increase, which causes a significant increase in the amount of sludge. Wastewater treatment plant sludges have high moisture content which can cause various problems during storage and transportation stages. Therefore, drying of sludge is an important process. In this laboratory-scale study, microwave and conveyor drying methods for drying sludges of wastewater treatment plants were examined on the basis of drying times and energy consumption. In the drying experiments, sludge weighing 20 g, 40 g and 60 g was used in the glass container. Microwave drying trials experiments at 360 W, 600 W and 800 W power, 2450 MHz frequency, conveyor drying trials at 1,8 m belt length, 60 ± 1 oC, 70 ± 1 oC and 90 ± 1o C, 0.2 m / min fixed band speed and air velocity of 1 m / s. Energy consumption increased with the increase of microwave power. The minimum energy consumption was measured as 0.015 kWh at 800 W and 60 g. The same values are observed when drying times are taken into consideration. Drying time decreased and energy consumption decreased with increasing drying temperature. The minimum energy consumption was measured as 4.1 kWh at 90o C and 20 g. The both drying systems were determined at 800 W for optimum time and energy. When the product is placed in a larger container and the surface area is enlarged, more drying can be achieved. When the results of the study were evaluated, it was found that different drying times were observed because the drying mechanisms of both driers were different and microwave drying was realized faster than conveyor drying due to the volumetric heating.