🔍 Key Concepts

• Oily-water separator stages – where does the polishing coalescer fit in the process? • Difference between hydrophilic (water-attracting) and oleophilic (oil-attracting) materials • Behavior of oil vs. water in a mixture – which tends to rise and which tends to sink in seawater?

💭 Think About

• First decide: in the polishing stage, are we trying to remove the last traces of oil or the last traces of water from the discharge? • If the filter surface attracts oil, what will happen to tiny oil droplets touching it? Will they stay small or form larger drops? • Once larger drops form, think about their density compared to water: would those larger oil drops move upward or downward in the separator housing?

✅ Before You Answer

• Be clear on which term means what: hydrophilic = water-loving, oleophilic = oil-loving • Confirm which component (oil or water) you ultimately want to separate out to meet MARPOL discharge limits. • Visualize the separator: after droplets coalesce into bigger globules, check whether oil or water will rise and how that matches each choice.