Compliant oily bilge water discharge is not an option

For vessel operators, poorly performing oily water separators can make it challenging to comply with strict IMO discharge regulations, potentially leading to fines and loss of reputation.

When the IMO made it mandatory for vessels over 400 gross tonnes (250 gross tonnes for oil tankers) to have oil-monitoring devices, it sent a strong environmental message to the industry. “We are often approached by customers who are struggling to treat their bilge water effectively with their current filters,” says Alfa Laval service development manager Rebecka Fogelquist Anthony.

Although Alfa Laval’s full-sized system, PureBilge, could do the job, it is overkill for many smaller vessels. “It is not always an appropriate retrofit choice, regardless of vessel size, as they do not require the biggest flow capacity,” she adds. In short, too big, too powerful and not cost effective for vessels with smaller bilge-water levels.

Alfa Laval responded to customer demand by coming up with a mini-sized treatment system suitable for smaller vessels. Called PureBilge Compact, this oily water separator takes up less space and is more easily installed, including for retrofits, while providing full compliance with IMO regulations that forbid the discharge into the sea of bilge water with an oil content exceeding 15 parts per million (ppm) for more than 10 seconds.

“IMO regulations forbid the discharge of bilge water with an oil content exceeding 15 ppm”

PureBilge Compact runs on a continuous, single-stage operation that requires a smaller holding tank and frees up space for payloads. Its capacity flow of 600 litres an hour is a fraction of the larger version’s 2,500 l/h-5,000 l/h, but suitable for smaller general cargo ships, passenger ships, fishing vessels and superyachts. Additionally, the PureBilge Compact is suitable for retrofit applications on larger vessels.

PureBilge Compact has received interest from shipyards specialising in smaller vessels, according to Alfa Laval HSS Pure & Engine Power global business manager Ayla Korlof.

Alfa Laval’s engineers have developed the mini-version for 24/7 unmanned operation. It does not require chemicals, absorption filters or membranes, further lowering replacement and maintenance expenses.  

Given the high cost of non-compliance, Alfa Laval has designed the compact system to overperform. Not only is it guaranteed to remove oil pollution below the 15 ppm IMO requirements, it can cut levels down to below 5 ppm. Crews, who the IMO expects to be fully trained for bilge-water compliance, can also see at a glance whether the vessel is meeting the regulations through an integrated oil content monitor. As Alfa Laval explains: “PureBilge Compact is a fully automated centrifugal separation system that ensures continuous high performance, regardless of variations in feed, oil shocks and rough weather conditions.”