We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Engines

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Is an Oily Water Separator?

By Jeremy Laukkonen
Updated: May 17, 2024
Views: 8,752
Share

An oily water separator is a device that is used on marine vessels to purify bilge water prior to pumping it overboard. The primary way that these devices extract oil is through gravity separation, though a variety of other filtration methods are often included as well. These devices have been present in new ship construction since the 1970s, and are also retrofitted into older vessels. When a crew or engineer modifies an oily water separator in order to pump large quantities of untreated bilge water into the ocean, it is often referred to as a magic pipe. Dumping untreated bilge water overboard is a violation of international convention, and may be prosecuted depending on where it occurs.

The lowest compartment present in a ship is referred to as the bilge, and any water that ends up on board eventually drains down there. In order to preserve positive buoyancy and avoid sinking or capsizing, this water must be periodically emptied. Heavily contaminated bilge water may be suctioned out when a vessel is docked, though in other cases it is pumped directly into the ocean. Since bilge water is often contaminated with a variety of undesirable compounds, including oil from machinery such as the engine or hydraulics, it must first be treated.

Prior to the 1970s, bilge water was typically pumped directly into the ocean without undergoing any filtration. Marine pollution conventions in 1973 and 1978 (MARPOL 73/78) addressed a variety of different ways that ships pollute, including oily bilge water, garbage, and sewage. Regulations were created that limited the amount of oil that could be present in discharged bilge water. Since these limitations were measured in parts per million (PPM), each vessel was subsequently required to have an oily water separator.

A typical oily water separator begins by exploiting the difference in specific gravity between oil and water. Oil will tend to rise to the surface of water, leaving a limited amount of globules in suspension. This often reduces the amount of oil in the water to about 100 PPM, which is about ten times more than is allowed. A variety of other filtration systems are then used to reduce the amount of oil to an acceptable level.

Due to MARPOL regulations, ships are typically required to keep extensive logs regarding the disposal of bilge water. In some cases, a crew or an engineer will falsify these logs and modify an oily water separator so that large amounts of untreated bilge water can quickly be dumped into the ocean. This modified system is often referred to a magic pipe, the use of which has been prosecuted successfully in the United States and other countries.

Share
WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Editors' Picks

Discussion Comments
Share
https://www.wisegeek.net/what-is-an-oily-water-separator.htm
Copy this link
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.