Experimental research on characteristics of sludge drying in a plate dryer

Sludge is the main byproduct of wastewater treatment. Sludge drying process is considered to be the necessary approach for sludge treatment and disposal. The characteristics of sludge drying at different drying stage were experimentally investigated in a plate dryer. Sludge drying process were carried out at different operation parameters, such as different drying temperature, thickness of sludge layer on the plate and back mixing ratio of dry sludge. The sludge drying process is featured with the evaporation at the surface and the inside moisture diffusion. The water evaporation rate was effectively improved with the proper drying temperature, sludge layer thickness and mixing ratio of dry sludge. The drying process of sludge mixed with oil shown preferable evaporation rate. Some preferable processing parameters were recommended for sludge drying in plate dryer, i.e. the temperature of 140 degrees C, depth of 30mm and 30% mixing ratio of dry sludge.