Reduced air and water emissions are essential parts of Royal Caribbean Cruises’ environmental stewardship strategy, according to its recent sustainability report. The company has been investing in emission purification systems (scrubbers), advanced wastewater, ballast water and bilge water treatment systems, in addition to energy saving technologies.
Today, 82 percent of its berths are covered by AWP (advanced wastewater purification) systems, according to Denise McCafferty, director of environmental programs, and Nicholas Rose, environmental regulatory lead, environmental stewardship. “The vast majority of our ships have plants, all our new ships, while many of our older ships have been retrofitted. The systems have membrane bioreactors or moving bed bioreactors,” McCafferty said.
“There are solids that are removed from the system to be landed, incinerated or discharged more than 12 miles from shore depending on where the ships are. Bio-residues (solids) go to a separate collection tank, while the clean water effluent is discharged. In the Baltic, the discharge will go to a shoreside reception facility, in other areas, it can be discharged four nautical miles from shore,” McCafferty explained.
Rose said that some of the water can be recycled in the scrubber systems, but other uses, such as washing outside areas of the ship, are not allowed by U.S. Public Health. However, McCafferty said that the outflow water is equivalent or better than most municipal systems and that Royal Caribbean’s standards exceed MARPOL wherever the brand operates.
In terms of liquids, the AWP covers some 98 percent of all the wastewater on the ship.
The Scanship system aboard the Quantum-class is designed to treat up to 90 cubic meters of wastewater per hour, although the general use is from 25 to 40 cubic meters per hour.
Currently all of Royal Caribbean’s newbuilds have Wartsila scrubber systems, according to Rose, who added: “We also have a 19-ship retrofit program going on, working with different vendors, including Wartsila and CR Ocean Engineering.
“We wanted to work with CR Ocean Engineering, because the footprint of their equipment seems much smaller than some of the other manufacturers, which will help alleviate some of the space constraints we have in retrofits as well as the newbuild programs.”
The Anthem of the Seas, for example, has two Wartsila multi-stream hybrid dual-water scrubbers, meaning they can run in open-loop mode using seawater to wash the exhaust or in closed mode using fresh water with a caustic additive, or in dual mode, running closed and open loop side by side, according to Rose. He explained that each tower has two chambers, which can be operated independently.
“The dual concept becomes important when the seawater does not contain enough alkalinity to scrub sulfur out of the emission load. It gives us the flexibility to run open and closed loop at the same time,” he added. When seawater is taken in, there is an in-line monitor that measures for salinity.
In open mode, when each tower is operated at its maximum capacity, the water flow is 1,500 cubic meters per hour, Rose said.
Before being discharged, both open-loop and closed-loop water is treated for pH (alkalinity), PAH (oil content), turbidity (particulate matter) and nitrates.
Both the air and water emissions are continuously monitored for MARPOL compliance, with self-adjusting systems for water-load, alkalinity, etc., ensuring that it is always in compliance.
“Whether it is the AWP or the scrubbers, we build our ships so we can operate anywhere in the world,” Rose said.