As a scrubber treats sulfuric exhaust gases, it generates sulfuric wash water. Although the scrubber neutralizes this using alkali, the wash water still contains harmful elements stemming from the combustion process. This is crucial to avoid ocean pollution, which will ultimately harm aquatic species, especially shellfish and corals. A scrubber water treatment unit plays a crucial role in boosting a greener shipping industry for a more sustainable future by removing below harmful elements.

Marine Scrubber Wastewater System

Polycyclic Aromatic Hydrocarbons (PAH)

Polycyclic aromatic hydrocarbons are various organic compounds of chemicals that exist naturally in coal, gasoline, and crude oil. PAH is also produced once coal, gasoline, and crude oil are burned, meaning that PAH is to find in marine exhaust gas streams. Before the IMO 2020 regulation, the PAH went into the atmosphere and contaminated the air for people to inhale. As the exhaust gas is scrubbed, the PAHs are absorbed by the wash water. It is unknown how low amounts of PAH affect human health. Still, large amounts of PAH are linked with cataracts, kidney and liver damage, and jaundice. Additionally, it may cause eye irritation, harm breathing passages, and frequent PAH skin contact, leading to redness and inflammation of the skin. Moreover, it can affect ocean chemistry as well as cause harm to aquatic species. With a scrubber water treatment unit, PAH is removed, which will ultimately deliver significantly improved marine life.

Particulate Matter (PM)

Particulate matter (PM) is an airborne substance of hundreds of different hazardous solid particles and liquid droplets. PM is, therefore, also often denoted particle pollution. Particulate matter may include both organic as well as inorganic particles, including elements such as soot, smoke, and liquid droplets. The scrubber also removes some of the PM. Still, as the exhaust gas is scrubbed, some PM is absorbed by the wash water. The particles of particulate matter can take different sizes, compositions, and origins. Some are possible to see with the naked eye, while others are so microscopic that they can only be seen through a microscope. Some PM stems from a direct source, such as an operating engine. Still, most PM takes form in the atmosphere when chemicals meet each other and form complex reactions. This is often the case with SOx and NOx emitted from power plants, industrial operations, vehicles, and vessels. PM makes up a significant health threat, as it is being inhaled. The smallest particles constitute the greatest health threat as they can enter deep into the human lungs and bloodstream. Fortunately, a scrubber water treatment unit can remove significant amounts of PM.  

Heavy Metals 

If a scrubber water treatment unit is installed with a coagulation module, it can remove heavy metals. Heavy metals are high-density metallic chemical matter. At high concentrations, it is toxic to humans and wildlife. Heavy metal intoxication can happen via contaminated drinking water, high ambient air concentration from exhaust gases, and food consumption. As the exhaust gas is scrubbed, the heavy metals are absorbed by the wash water.

Two problematic and harmful heavy metals are cadmium and mercury.

Cadmium can cause kidney failures, lung diseases, and lung cancer. Long-term exposure to cadmium can lead to bone defects in humans and animals. The LiqTech scrubber water treatment unit can reduce cadmium to less than 0.15 µ per liter.

High mercury concentrations can cause brain malfunctions, kidney damage, lung diseases, eye irritation, inflammable skin, vomiting, and diarrhea. Previously, mercury has been found in the oceans, causing fish to be contaminated, ultimately resulting in food chain pollution. The LiqTech scrubber water treatment unit can reduce mercury significantly to less than 0.05 µ per liter.  

A water monitoring unit (WMU) is placed before the discharge outlet to ensure that the closed-loop scrubber wash water always abides by IMO's discharge limits. Learn more about the scrubber water discharge limits.

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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.


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