Question 65 1AE01 - First Assistant Engineer

The Correct Answer is C **Explanation for Option C (Type III):** Type III Marine Sanitation Devices (MSDs) are defined by the US Coast Guard regulations (mandated under the Clean Water Act) as devices that prevent the overboard discharge of treated or untreated sewage. They function primarily as holding tanks or recirculating systems. Crucially, a standard Type III MSD is simply a **holding tank** used **solely for the storage of sewage and flushwater** until it can be properly pumped out at an approved reception facility (pump-out station) or discharged legally where permitted (e.g., beyond the 3-nautical-mile limit). This storage occurs passively at ambient air pressure and temperature. **Why the other options are incorrect:** * **A) Type I:** Type I MSDs are flow-through treatment devices. They biologically or chemically treat sewage and use maceration and/or chlorination to reduce the coliform count to less than 1,000 per 100 milliliters and total suspended solids to not greater than 150 mg/l before discharge. They do not function *solely* as storage units. * **B) Type II:** Type II MSDs are also flow-through treatment devices, but they provide a higher level of treatment than Type I. They must reduce the fecal coliform count to less than 200 per 100 milliliters and total suspended solids to not greater than 100 mg/l before discharge. They are more robust treatment plants than Type I but are not *solely* storage units. * **D) Type IV:** The designation "Type IV" is not a recognized category under the current US Coast Guard regulations (33 CFR 159) for federally certified MSDs. While older or non-standard systems might occasionally be referenced by this number in informal contexts, it does not represent a standardized, federally defined type of storage-only device.