 Another benefit of drying is a reduction in volume and weight.In the area of sanitation, drying of sewage sludge from sewage treatment plants, fecal sludge or feces collected in urine-diverting dry toilets (UDDT) is a common method to achieve pathogen kill, as pathogens can only tolerate a certain dryness level.In addition, drying is required as a process step if the excreta based materials are meant to be incinerated.