What type of device is used for the storage of sewage and flushes water at ambient air pressure and temperature?

The correct choice is Type III Marine Sanitation Device (MSD). A Type III MSD is designed specifically for holding sewage until it is pumped out at a designated facility onshore. This type of system does not treat the wastewater but instead stores it, allowing it to be disposed of in compliance with regulations.

Type III MSDs are essential for vessels that operate in areas where overboard discharge of untreated sewage is prohibited. They can maintain their contents at ambient air pressure and temperature, making them practical for a variety of marine operations.

In contrast, Type I and Type II MSDs are designed to treat sewage before discharge, meaning they process wastewater to meet certain standards. Type IV MSDs refer to systems that utilize vacuum technology, often using vacuum pumps to manage sewage, which is different from the storage function of a Type III device.