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The mobile disposal boats


How bilge oil removal vessels keep rivers clean

Inland waterway vessels are viewed as particularly eco-friendly compared to other means of transport. However, they still produce solid and liquid waste from their shipping operations. To ensure that this is not fed into rivers such as the Rhine, clean-up vessels take over responsibility for pumping out and disposing of the waste. Wolf-Simon Greling, Managing Director of the Bilge Oil Removal Company, explains how this works in actual practice.

Waste accruing from the process, manufacturing and chemical industries was fed into flowing waters such the River Rhine for many decades and created a high degree of contamination. Inland waterway vessels fed their used oil and lubricants into rivers too. It is true that the quantities involved were comparatively small, but they still damaged the water quality and the animals and microorganisms living there.

But where does the used oil come from? So-called bilge oil accumulates in any vessel. Bilge is the term to describe the lowest part inside the ship, where leaking water and condensation as well as oil products from the drive technology collect. The water/oil waste mixture is also called bilge water or bilge oil. It consists of about 90 – 95 per cent water and 5 – 10 per cent oil. The water/oil mixture accumulates mainly as a result of engine oils and lubricants escaping from the vessel’s drive system. Concentrated used oil is another waste product on board ships and it is collected in a separate tank.

Bilge oil removal is not a national issue

Experts began to rethink the process of thoughtlessly disposing of ships’ waste in rivers during the 1950s – when the first bilge oil removal vessels were put into service and were able to handle the bilge oil. This was initially a business consideration. The German states later funded the disposal process and were supported by the federal German government for many years. However, rivers such as the Rhine do not stop at the borders of states or national frontiers. It was therefore necessary to create new European rules. As far as the River Rhine was concerned, this marked the birth of the CDNI, an agreement covering the collection, delivery and disposal of waste for Rhine and inland waterway shipping.

This agreement, which was also signed in 1966 by all the surrounding countries – the Federal Republic of Germany, the Kingdom of Belgium, the French Republic, the Grand Duchy of Luxembourg, the Kingdom of the Netherlands and the Swiss Confederation – came into force on 1 November 2009 and regulates both the responsibility to dispose of specific waste and implement the rules. 

The Bilge Drainage Association (BEV), an inner-state institution, has been entrusted with the task of implementing the agreement in practice within Germany. The Association makes use of contractors, which guarantee disposal, including the Bilge Oil Removal Company. This accepts the solid and liquid waste on its fleet of vessels on the rivers.

The bilge oil removal vessels are bright yellow

The Bilge Oil Removal Company is a firm with seven vessels, so-called bilge oil removal boats. They operate as sector boats along the entire River Rhine and are easily recognisable from a distance thanks to their bright yellow colour. Each boat has a set berth and operates within its defined working radius. The fixed sector vessels are complemented by a river boat, which travels up and down the entire River Rhine and its tributaries – as far as the River Danube. The Bilge Oil Removal Company therefore handles the disposal of bilge oil along the River Rhine, the north-west canal system and the so-called “canal rectangle” as far as Bremen.

Bilge oil removal vessels have a huge advantage: they are flexible and travel directly to the inland waterway vessels so that the latter do not have to berth at a set point and this prevents any waste of time or money – true to the motto: if the mountain will not come to Mohammed, the disposal vessel must come to the ship.

The special boats for removing bilge oil are structurally small bunker boats. This is the name for vessels that are equipped with one or several integrated tanks and transport fuels. On average, the boats can accommodate up to 55 cubic metres of liquid – distributed over several small integrated tanks, which are connected to each other by pipes.

To help people understand the concept, it is rather like a huge, highly efficient vacuum cleaner, which sucks up the oily mixture using a vacuum process and feeds it into its integrated tank. This is a very safe handling procedure since, if the suction pump should break down, which is highly improbable, the liquid flows back into the tank and therefore cannot technically reach the surface water.

The siphoned mixture of water and oil is separated into used oil and water on board the special boats and the remaining water is finally purified using filtration, before it is even possible to feed back the fully filtered water into the river. The used oil, on the other hand, is retained on board the special boats.


We reveal:

  • How bilge oil removal works
  • How the bilge oil removal process works
  • What happens during the individual purification phases
  • Where the recycled material ends up

Discover in our checklist how the bilge oil removal boats relieve inland waterway vessels of oily waste.


Vessels are normally emptied once a year

Deciding how often and how much oil is ultimately drained and collected is a very individual matter. ‘There’s no set rhythm for bilge oil removal – everything’s a one-off procedure. This comes down to the fact that vessels are not normally constructed in line with a set pattern, but each ship is a prototype,’ Wolf-Simon Greling explains. An inland waterway vessel is normally emptied once a year. The quantity of the liquid ship’s waste that is taken on board differs greatly and can vary between one and three-and-a-half cubic metres – i.e. about six or seven full water butts. Much larger quantities are expected from older vessels.


How the Bilge Oil Removal Company uses its special vessels:

  • 7 bilge oil removal boats
  • Between 1,000 and 3,500 litres of used oil pumped out of each inland waterway vessel
  • 4,000 disposal processes for vessels every year
  • Support if any accidents occur
  • Collecting and disposing of solid ships’ waste

Payment for disposal takes place, however, not according to the quantity of liquid that is drained, but according to the amount of fuel that is taken on board! An electronic payment system for collecting and disposing of waste from shipping operations containing oil and grease was introduced at the beginning of 2011. The disposal of this waste is funded via a fee that is paid by the ship’s operator. The ship’s owner must apply for an ECO account and an ECO card for this purpose. The amount reaching the tank is noted during any fuelling procedure. ‘A particular disposal fee has to be paid for each litre that is taken on board. It’s the funding system that is governed by international law in order to be able to professionally dispose of all waste from shipping operations,’ Greling explains.

Who pays what? Payment in line with the ‘polluter pays principle’

All the vessels that are operating in the area where the CDNI agreement applies and carry tax-free fuel oil are obliged to pay for disposal. They have access to the reception points, which are distributed across the entire area covered by the agreement, where ships’ operating waste containing oil and grease can be handed over without any restrictions. Ocean-going ships, including fishing vessels and sports boats, which normally do not have any rights to purchase tax-free fuel oil, constitute exceptions to this rule. The costs of disposal, which are governed by the fuelling procedure, are the responsibility of the ship’s operator. The amount of the fees depends on the quantity of the fuel that is put on board. The disposal companies are funded by the fees that are collected.

Bilge oil removal has been a success story for environmental protection for three decades. The latest new entrant is the Bilge Oil Removal Company and its newly constructed special vessel is called ‘Bilgenentöler 10’. The boat, which is based in Regensburg, is operated as a pure collection vessel. That is to say, the water/oil mixture is still separated and processed on board, but is handed over to a processing unit at a land-based water treatment centre following preliminary treatment.

A new site has recently been established at the Minden inland waterway junction. The ‘Bilgenentöler 4’ operates here as a special boat and takes on board liquid and solid waste from vessels. The special feature here is that it travels as far as Bremen and therefore even provides disposal services for inland waterway vessels in waters that are affected by tides.

The future of bilge oil removal

What does the future of bilge oil removal look like in the longer term? More and more vessels are being constructed in an environmentally-friendly manner. Drive systems are changing. Will there still be such a thing as bilge oil in the future? ‘It’s true that drive systems are changing. However, it’s not clear when and to what degree this will take place. Inland waterway vessels are designed for long-term service and there are fairly long transitional arrangements for existing engines. Most inland waterway vessels are still equipped with classic diesel engines,’ says Greling and adds that oils would still probably accumulate as a result of lubrication applications, even if there was a switch to hydrogen.

However, there is no denying that the quantity of mixtures of water/oil on board is tending to decline because the engines are better designed and the hulls are less prone to leakage than in the past. The waste that occurs may be less, but is much more concentrated and this therefore increases the requirements for handling and disposal.

Wolf-Simon Greling is a lawyer and has been Managing Director of the Bilge Oil Removal Company (BEG) and the Rheintank firm since July 2020. He is the company lawyer for Rhenus Transport and handles all the legal issues related to the topic of shipping. His place of work is naturally at Europe’s largest inland waterway port in Duisburg!

Are you a member of an inland waterway vessel’s crew or active in bilge oil removal? We look forward to receiving your comments and opinions about how you believe the sector will develop in future.

Are you interested in bilge oil removal or inland

Collecting and disposing of waste from shipping operations which contains oil and grease and waste water from inland waterway vessels in an environmentally-friendly manner.


Inland waterway vessels: In service on Europe’s waterways.



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