What consists of two parallel sets of screens for the purpose of filtration?

The correct answer is grating screen. Grating screens typically consist of two parallel sets of screens, which allows for enhanced filtration efficiency. The design helps in effectively removing larger solids and debris from a liquid stream, such as wastewater, ensuring that finer particles can be further treated or filtered downstream. This configuration improves the capture of solids while allowing flows to pass through more smoothly.

Grating screens are optimal in applications where a significant amount of solid waste needs to be filtered out before further processing. Their structure allows for better support and easier cleaning or maintenance, which contributes to prolonged equipment life and reduced operational issues.

Other options, such as grit screens, disk screens, and mesh screens, serve specific roles in filtration but do not specifically feature the dual parallel set design characteristic that is essential for their classification as grating screens.