Three separate methods of solids removal from a physical chemical industrial process are:

• A. Screenings
• B. Settling
• C. Filtration
• D. Screenings, Settling, and Filtration

Answer: (D)

Solid removal in physical‑chemical processes is best achieved with a staged approach that handles different particle sizes. Large solids are best removed first with screening, which protects pumps and downstream equipment from clogs and damage. After that, gravity-based settling (clarification) removes a substantial portion of the suspended solids by letting them settle to the bottom of a tank, reducing turbidity and the solid load. Finally, filtration acts as a polishing step, catching the finer particles that escape the screen and the settler to produce a clearer effluent and protect downstream processes. When a system uses all three steps—screening, settling, and filtration—it can effectively remove a broad range of solids, from large debris to very fine particles, which is why that combined approach is the best fit. Relying on any single method would miss solids outside that method’s effective range, leaving potential problems downstream.