Some pressure filter systems for dewatering use a ____________ system to help dewater sludges high in oils and grease

The correct choice is the precoat system, which is specifically designed to enhance the dewatering process, especially for sludges that contain high levels of oils and grease. In a precoat system, a filter medium, often made from materials such as diatomaceous earth or perlite, is applied to the filter surface before the actual filtration of the sludge begins. This precoat layer serves multiple purposes: it acts as a support structure for the sludge that is being filtered, improves the filtration efficiency, and helps in the removal of the oily or greasy components by providing a surface that adheres better to these substances.

The use of a precoat ensures that the oils and greases do not clog the filter media as quickly as they might without this preliminary layer, thereby improving the overall dewatering process and reducing the frequency of filter cleaning or replacement.

In contrast, other systems such as vacuum, heating, or compressed air are not specifically tailored for dealing with sludges high in oils and grease. For instance, vacuum systems utilize a differing principle by creating a negative pressure to facilitate drainage but may struggle with oily materials. Heating systems might help reduce the viscosity of grease but do not specifically enhance the filtration capabilities in high-oil scenarios. Compressed air