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What sounds like a niche market is one of the top prerequisites for vessels to operate without causing pollution on the world’s waterways. We are talking about bilge oil separation. This involves specialized disposal vessels. They ensure that waste oils and lubricants, which are released when operating inland waterway vessels, do not make their way into rivers. This type of contamination would not only undermine the positive environmental credentials of inland waterway vessels, but would also have serious consequences for water quality as well as the animals and microorganisms living there. While this was an accepted practice for many decades, there are now official regulations that have been introduced to protect waterways and their population. Bilge oil separation vessels still handle one of the main tasks here, the disposal of bilge oil.
Cleaning up the rivers
Waste materials from the process, manufacturing and chemical industries were fed into flowing waters for a long time as part of the ongoing process of industrialization. However, shipping operations were also one of the contributors to the serious contamination of waterways like the river Rhine. Finally, the authorities sounded the alarm bell from the late 1950s onwards, in the face of the high levels of pollution. Initially made available by companies, then supported by the German federal states and the federal government, efforts were made to dispose of solid and liquid waste generated by vessels – and the first bilge oil separation vessels started operating on the waterways. An international regulation was finally introduced with the signing of the CDNI in 1996, the Convention on the Collection, Deposit and Reception of Waste Generated during Navigation on the Rhine and Other Inland Waterways. The CDNI came into force in 2009 and it has been the regulation for the proper disposal of waste generated by vessels like bilge oil by bilge oil separation vessels.
What is bilge oil and where does it come from?
Bilge oil takes its name from the part of the vessel where it gathers: the lowest part of the ship’s hold, the so-called “bilge”. This is where any leaking and condensation water as well as engine oils and lubricants, which are caused by the vessel’s operations, accumulate. This waste mixture of water and oil is also described as bilge water or bilge oil. Approximately 90 – 95 percent of this mixture is water and five-ten percent is oil. Another waste product on board the vessels is concentrated waste oil, which is gathered in a special tank.
“Bibos”, the floating disposal vessels
The Bilge Disposal Association guarantees the implementation of the CDNI regulations in Germany. The Rhenus subsidiary, the Bilge Oil Separation Company, is responsible for implementing this, for example, and it covers the entire river Rhine with its tributaries, the north-west German canal system and the so-called “Canal Rectangle” as far as Bremen: it uses seven bilge separation vessels, commonly known as “Bibos”, for this purpose. The great benefit of the bilge oil separation vessels is that they are flexible and directly make their way to the inland waterway vessels so that the latter do not have to wait or travel to a set disposal point; they therefore do not waste any time or money. Each of the vessels can filter the water/oil mixture from as many as eight inland waterway vessels and pump out the remaining quantities of bilge and waste oil on a daily basis.
A newly constructed special vessel, which is solely operated as a collection vehicle, forms a special part of the Bilge Oil Separation Company’s fleet. That is to say, the water/oil mixture is still separated and processed on board, but is discharged at a land-based water treatment plant after the preliminary treatment. Another special vessel, which actively operates in the Minden waterway intersection as far as Bremen, is capable of enabling inland waterway vessels to dispose of their waste in waters that are subject to tides.
How oil separation takes place
The bilge oil separator vessels all have one or several tank cells, each of which on average is able to accommodate up to 55 cubic meters of liquids. The oil mixture is suctioned out using a vacuum process as if it were an enormous, powerful vacuum cleaner. As the liquid will flow back into the tank in the unlikely event of the vacuum pump breaking down, this secure procedure ensures that no oil can make its way into the surface water. The water/oil mixture, which has been suctioned out, is already cleaned on board the special vessels. To achieve this, it passes through various stages and chambers inside the vessel in order to be roughly cleaned by filtration and separation at first and then separated into water and waste oil. Because the water usually still contains a small amount of oil after the separation process, the remaining water is finally cleaned in an ultra-filtration unit. The fully filtered water is so clean that the bilge oil separator vessels can then feed it back into the waterway. The waste oil remains on board the “Bibos” and is disposed of professionally at a special waste oil recycling point during the next stage.
Services every year
How frequently and how much oil is ultimately pumped out and collected is a very individual matter. “Nothing in terms of bilge oil separation has a recurring rhythm – everything is unique. This is because the vessel construction process isn’t normally part of any series production work, but each vessel is a prototype,” says Wolf-Simon Greling, the Managing Director of the Bilge Oil Separation Company, explaining the situation. An inland waterway vessel normally undergoes this vacuuming process once a year. As each inland waterway vessel produces between 1,000 and 3,500 liters of waste oil, the company’s tankers pump out several million liters of bilge water and waste oil every year.
All the vessels, which operate in the geographical area where the CDNI applies and bunker tax-free gasoil, have to pay for disposal services by bilge oil separator vessels. The latter have access to reception points along the entire area covered by the convention, where the operating waste from the vessels can be disposed of free of charge.
In the end, it is not the quantity that is pumped out, but the quantity taken on board that determines how high the fee is for using the bilge oil separator vessels. The amount of fuel pumped on board during the fueling process is noted in a so-called ECO account and this ultimately gives rise to the costs for disposal for the vessel’s operator.
“A particular disposal fee has to be paid for each liter of fuel taken on board. This is the internationally agreed funding system in order to be able to professionally dispose of all waste generated by vessels’ operations,” says Wolf-Simon Greling, Managing Director of the Bilge Oil Separation Company.
Innovative shipping technology vs bilge oil separation?
However, what does the future of bilge oil separator vessels look like in the longer term? More and more vessels are being constructed in a sustainable way. Drive systems are changing. Will there still be any bilge oil at all?
“It’s true that drive technologies are changing. However, it isn’t possible to determine at the moment when and to what degree this is taking place. Inland waterway vessels are designed for long-term service and there are fairly long transitional regulations for existing engines. Classic diesel engines have still been installed in most inland waterway vessels,” Greling states. And even if there is a switch to using hydrogen, waste oils will probably continue to accumulate through lubrication.
However, generally speaking, it is true that the quantity of water/oil mixtures on board is on the decline, because engine designs are being improved and the vessels’ hulls are more leak-proof than in the past. This may result in less residual waste, but it is much more concentrated and what is required is therefore increasing too.
Active participation therefore continues to be necessary for the entire sector and also for bilge oil separation in order to make full use of the potential of inland waterway shipping. However, the bilge oil separation vessels, which act as floating disposal vessels, are still an indispensable element to guarantee that the whole sector does not cause pollution.