In 2013, we announced our plans to install advanced air quality systems (AAQS), generically known as exhaust gas cleaning systems (EGCS) or scrubbers, on our ships. These systems remove sulfur compounds and particulate matter from our ships’ engine exhaust at any operating state of a ship – at sea, during maneuvering and in port. Due to the initial limited availability of ship-ready AAQS for marine applications, Carnival Corporation led the way in developing the technology to successfully function in the restricted spaces available on cruise ships. Making the necessary investments, — totaling approximately $500 million of installations to date — has led to a significant development in shipboard environmental technology.

As of FY2018, 74% of our fleet is equipped with AAQS and we plan to develop and deploy the systems on more than 85 ships across our global fleet by 2020 – significantly improving the quality of air emissions from our ships and reinforcing our environmental commitment.

Through extensive independent testing, the systems have proven capable of outperforming low-sulfur fuel alternatives such as marine gas oil (MGO) in terms of overall cleaner air emissions and no negative environmental impact to oceans and seas, all as originally intended by the International Maritime Organization (IMO). Ships using AAQS to scrub heavy fuel oil (HFO) are also effective in reducing particulate matter and typically have lower sulfur oxide (SO2) emission levels than MGO, as well as lower NOx and fewer polycyclic aromatic hydrocarbons (PAHs).

Open Loop System

Carnival Corporation’s AAQS are open loop systems that use a sea water spray for removing sulfur from engine exhaust, converting it to sulfates (which are abundant the sea) before returning the seawater to the ocean. The seawater is monitored by pH, PAH and Turbidity sensors through this process to ensures that it meets or exceeds the IMO required standards before returning to the ocean. A further filtration process while in port ensures a seawater quality meeting other applicable environmental standards for operations.

carnival’s Open Loop Advanced Air Quality System


1. Seawater Pump & Variable Frequency Drive
2. Seawater Filter
3. Sulfer Removal Tower
4. Static Mixer
5. Dilution Pump & Variable Frequency Drive


Compliance Monitoring Equipment is used to monitor the Compliance Parameters for Exhaust and EGCS wash water.

Compliance Monitoring Equipment Diagram

Gas Analyzer – measures the SO2 and CO2 content of the exhaust gases which allows the SO2/CO2 ratio to be calculated.

Sea Suction Rack (Rack 1) – measures the PAH and Turbidity of the inlet wash water at the sea suction. Although not required for compliance, on some systems pH is also measured.

DeSOx Outlet Rack (Rack 2) – measures the PAH and Turbidity of the wash water at the outlet of the DeSOx Tower.

Overboard Discharge Rack
(Rack 3)
– measures the pH of the wash water at the overboard discharge.

Advanced are System image

Using Advanced Air Quality Systems

Removes 99% of Sulfur

Removes > 50% of Particulate Matter

Reduces 10% of Nitrogen Oxides

Independent Two-Year Scientific Wash Water Study

In March 2019 we released the Carnival/DNVGL 2018 Wash Water Assessment a four-year scientific wash water study that collected 281 wash water samples from 53 Carnival ships, conducted lab analyses on each sample for 54 different parameters including PAHs and metals, and partnered with DNVGL to evaluate and compare the results to major national and international water quality standards. To provide further understanding and perspective on the quality of the discharged wash water, the study demonstrated that the AAQS wash water samples were well below the limits set by several major national and international land-based water quality standards up to and including the World Health Organization (WHO) standards for drinking water.

Specific to IMO wash-water requirements, the study confirmed results from previous studies showing the quality of the water used in the AAQS process was always far below the IMO monitoring limits for PAHs and the annual limits for nitrates. In fact, when measured against IMO standards, the average wash water test results in this study were over 90 percent lower than maximum allowable levels. In many cases, the materials were completely undetectable in the laboratory testing process.

Other standards the results were compared against include, German Waste Water Ordinance, which as a “point source discharge” standard was the most directly applicable, and also the EU Industrial Emissions Standards and the Surface Water Standards of the EU’s Water Framework Directive, both “water quality” standards. The AAQS test results compared favorably with all of these major benchmark standards, demonstrating that the composition of the water was not only consistently below, but in most cases, significantly below the most stringent limits. The full study briefing can be found at:

Emissions Profile

To further enhance our emissions profile, we have also started to install a catalytic reactor on the engine exhaust to reduce particulate matter (PM) even before the exhaust reaches the AAQS tower, which also is effective in reducing PM. Our standard AAQS removes 99% of sulfur sulfur (in the form of SO2) and up to 75% of the particulate matter, including elemental and organic and black carbon, as well as PAHs. The combined effect of the AAQS, catalytic reactor and other systems is a further reduction of the particulate matter, including the very fine PM 10 and 2.5 particles. The use of AAQS with HFO fuel and other systems creates a reduction of between 5-15% compared to MGO fuel use.

All AAQS comply with international regulations and are certified by a classification society. In addition, all systems are equipped with continuous monitoring equipment to automatically record required parameters – specifically SO2 in the exhaust gas and pH, PAH and Turbidity in the wash water.

In 2018, Carnival Corporation was a founding member of Clean Shipping Alliance 2020, a new industry association consisting of 39 leading shipping and maritime companies, and providing education and information on the benefits of AAQS, as well as a public voice. Collectively, these companies represent over 3,000 ships across the sectors of commercial shipping and cruising.