Study of the process of sludge sediment drying due to solar energy

Abstract. After treatment of municipal wastewater sludge in treatment plants is not removed for several decades. This has led to the accumulation of huge amounts of sludge on sludge sites, which is a threat to the environment. The purpose of this study is to accumulate statistical data on the process of drying sludge and to study the effect of the amount of product mixing on the specific productivity relative to the moisture removed from the material. The experiments were performed using a reduced model of a solar industrial dryer. The model was located with the orientation of the elongated horizontal axis in the east-west direction and was extended outside the building into the environment using a special system. Evacuation of steam coming from the material to be dried was performed by molecular diffusion through a window, which was located on the north wall of the model and closed by a louver. The experiments changed: season, weather conditions, layer thickness and initial moisture content of the material, the amount of mixing. Both ambient conditions were determined: temperature and relative humidity, "clarity-cloudiness", and conditions in the drying chamber: temperature and relative humidity in the chamber volume and in the material layer, material humidity, specific productivity of the dryer model, in relation to the moisture removed from the material during the day. It is determined that the most noticeable changes in the specific productivity of the laboratory dryer are caused by changes in ambient temperature, "clarity-cloudiness"; relative humidity of the outside air and the amount of mixing. The layer thickness and the initial humidity of the material do not significantly affect the specific productivity of the dryer. Key words : waste water, sludge sediment, solar dryer