What method uses a partially submerged rotating drum for solid treatment?

The method that utilizes a partially submerged rotating drum for solid treatment is the vacuum filter. This system works by creating a vacuum that draws wastewater through a filter medium, allowing solids to be retained while the treated water passes through. The rotating drum facilitates the continuous separation process, where the solids are accumulated on the filter surface. As the drum rotates, it periodically comes out of the liquid, allowing for the solids to be discharged and dried by the air.

In contrast, composting involves the biological degradation of organic material, relying on microorganisms and is not related to a rotating drum mechanism. The belt filter, typically a stationary device, operates by allowing water to drain through a moving belt covered with a filter medium. Sand drying beds are passive systems where solids are spread on a bed of sand for drying, not utilizing a rotating component. Each of these methods functions differently and is selected based on the specific requirements of solid treatment and water quality goals.