Which type of waste solids is most likely to be sent to a rendering reclamation?

Scum is the correct answer because it refers to the floating layer of solids that accumulates on the surface of wastewater. This layer is primarily composed of fats, oils, grease, and other organic materials that rise to the top during the treatment process. Rendering reclamation involves converting animal by-products into useful products, making scum a suitable candidate for this process due to its organic nature.

In contrast, screenings consist of larger debris such as plastics and sticks, which are typically removed from wastewater early in the treatment process and are not suitable for rendering. Grit, comprising sand, gravel, and other inorganic materials, is removed during primary treatment and is not organic, thus making it unsuitable for rendering as well. Secondary sludge results from biological treatment processes, primarily consisting of microorganisms and organic matter; while it can be treated further, it is usually disposed of in anaerobic digesters rather than being rendered.