Conventional and greenhouse sludge drying beds for dewatering septage (Nepal)

In this study two different sludge drying beds have been studied as a method of dying for preliminary treatment. They were built using locally available materials i.e., aggregate and sand. Sand used in this method has coefficient of uniformity of
2.33 and effective diameter of 0.41 mm. One of the sludge drying beds was prepared using greenhouse and other was conventional sludge drying bed. Different depth of sludge, 10 cm 20 cm and 30 cm, were maintained in the sludge drying bed and parameters like temperature, volatile solids, moisture content and total solids were studied in order to find out the drying efficiency of sludge. The reduction of drying period was four days earlier than the conventional drying bed to obtain 60% total solids. Also, the maximum temperature inside greenhouse was 30°C and minimum temperature inside greenhouse was 13°C. Use of greenhouse not only reduced the time of drying but also helped in stabilization of sludge.