🔍 Key Concepts

• 33 CFR Part 159 – Marine sanitation devices (MSDs) requirements for Type II biological treatment units • Purpose of disinfection after biological treatment (what problem are we still trying to solve?) • Common shipboard disinfection methods: chlorination (hypochlorite) vs ultraviolet (UV) irradiation

💭 Think About

• Ask yourself: Does the Coast Guard typically allow more than one approved method for disinfecting sewage effluent, or just one very specific method? • Think about which methods are practical and commonly installed on ships’ sewage treatment plants you’ve seen or studied. • Consider whether a biological treatment plant can legally discharge without any disinfection when it’s operating properly.

✅ Before You Answer

• Verify in 33 CFR 159 whether disinfection is still required for biological treatment plants before discharge. • Check which disinfection methods are explicitly recognized for marine sanitation devices (is UV included, is hypochlorite included, or both?). • Confirm whether any option claiming "only" one method matches what you’d reasonably expect for approved shipboard equipment.