With the IMO 2020, marine exhaust gas cleaning systems, also referred to as scrubbers, have become imperative to obtain compliance. Scrubbers can take three forms, being open-loop, closed-loop, and hybrid. Learn more about the differences between an open-loop, closed-loop, and hybrid scrubber. Yet, several countries have banned the use of open-loop scrubbers and scrubber wash water discharge to fight ocean acidification. You can see our complete list of countries that have adopted a ban here.


As of today, many vessels still operate with open-loop scrubbers. However, this is not a sustainable or viable solution as the discharge of sulfuric wash water into the oceans harms ecosystems and aquatic species, especially shellfish and corals, by causing ocean acidification. And although local prohibitions are a great start to accommodate a desulfurized shipping industry, it is just the beginning as many in the shipping industry have requested a global effort to seek common ground. Therefore, it is also expected that the IMO will sanction a new work plan at its next Marine Environment Protection Committee (MEPC), discussing environmental issues under IMO’s remit. This new work plan focuses on aligning the regulations and bans for scrubber wash water discharges internationally. Here, they can decide when, where, or if to sanction scrubber wash water discharge. And with new global restrictions in sight, it becomes impossible to maintain an open-loop scrubber operation. The 76th MEPC session is to be held in June 2021.


With these new stringent environmental regulations, new innovative solutions are required to obtain full compliance. And this is where open-loop to closed-loop scrubber conversion enters the picture.


The Conversion to Compliance

The conversion to compliance becomes more and more imperative. Therefore, an increasing number of open-loop scrubbers are also designed as hybrid-ready, making it easy for shipowners to convert to a hybrid scrubber, operating in both open-loop and closed-loop mode.


You can quickly obtain full compliance with even the most stringent environmental regulations by converting your open-loop scrubber to a closed-loop or hybrid scrubber. Often, the conversion is from a closed-loop to a hybrid scrubber, which enables the scrubber to operate in open-loop and closed-loop mode. Yet, with the industry moving towards zero emissions, it is expected to see more conversions to closed-loop as well as more innovative closed-loop scrubber solutions. A conversion lets shipowners continue to operate their scrubbers, which they have invested millions of dollars in. Still, their pollution is reduced significantly.


A closed-loop scrubber is an exhaust gas cleaning system, which reduces sulfur by 98 %. The environmental advantage lies in pH neutralization, which ensures that the sulfuric wash water is neutralized. A closed-loop scrubber requires a water treatment unit (WTU) and a sludge handling facility. Learn more about marine scrubbers and their basic components here. With a WTU, the bleed flow from the scrubber’s process tank is treated. The treatment of scrubber wash water consists of suspended solids removal, ensuring that no polluted wash water is discharged into the sea. Sludge is stored in a holding tank for safe and sustainable onshore disposal. Sludge can be dewatered with a filter press to ensure total solid and liquid separation for easy and cheaper handling. 


And there is a financial gain as well because, with a closed-loop scrubber, you are still allowed to use heavy fuel oil (HFO), which is a high-energy content that is complex to refine. HFO is cheaper than low sulfur fuels, meaning that it enables a competitive OPEX. When the fuel spread peaked on the 3rd of January 2020, at $321.5/mt on a FOB Rotterdam barges basis, the return on investment (ROI) was less than 6 months. Consequently, closed-loop scrubber technology ensures that your vessel can operate compliantly and cost-effectively now and in the future. Learn more about what a closed-loop scrubber is here


A scrubber and the connected WTU and sludge handling facility is a customized solution, which is made to match your specific needs. At LiqTech, we have thoroughly developed a WTU based on innovative, patented membrane technology. It is a flexible solution, and you can always expand the solution to obtain more capacity. Besides conversion, it is possible to install closed-loop scrubbers as a completely new-build system on your vessel. 


New call-to-action

Based on more than 20 years of experience in the filtration industry and partnerships with leading scrubber manufacturers, shipowners, and shipyards, we have extensive experience providing open-loop to closed-loop or hybrid conversion with superior marine scrubber wash water treatment systems. The technology is market-proven, installation is hassle-free, and we support you 24/7. See the below video to learn more about our experiences and competencies within marine scrubber applications. 


Want to learn more?

Visit our Marine Knowledge site to learn everything worth knowing about marine scrubbers, wash water treatment, and how to comply with the IMO 2020 sulfur cap.

Download Marine Industry Knowledge Ebook

Liked this blog post? Then we think these are just for you


Why Use a Pool Filtration System?

With the IMO 2020, marine exhaust gas cleaning systems, also referred to as scrubbers, have become imperative to obtain ...


What Is Pool Filtration?

With the IMO 2020, marine exhaust gas cleaning systems, also referred to as scrubbers, have become imperative to obtain ...