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Large cruise ships can generate up to a ton of waste per day — the equivalent of an entire neighborhood’s worth of waste. But far from polluting the oceans, these modern vessels treat, separate and even reuse most of what they produce, adopting cutting-edge technologies to ensure sustainability on the high seas.
The cruise ship that generates as much waste as a neighborhood – Imagine a floating city with more than 5 people, including crew and passengers. This is the daily scenario on cruise ships such as the Royal Caribbean Oasis class or MSC mega-ships. On average, each vessel of this size generates around 1 ton of solid waste per day. This amount includes food scraps, plastic packaging, cardboard, glass, cans, toilet paper and even toxic waste such as oil and batteries.
If that sounds like a lot, that's because it is. waste management on cruise ships It is one of the most complex operations in the maritime sector. And it is all done on board — without relying on external collection during the days of navigation.
How waste is separated and treated on board the ship – a cruise ship that generates as much waste as a neighborhood
Behind the scenes on the ships, environmental teams operate as true urban sanitation departments. The process begins with the selective collection carried out by trained crew members, which separate waste into categories: plastics, metals, glass, paper, organic and hazardous.
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After that, the material goes to the waste processing center, located in the technical areas of the vessel. There:
- Plastics and metals are pressed and stored for disposal on dry land;
- Glasses are crushed to take up less space and avoid accidents;
- Papers are compressed in recyclable bales;
- Oils and greases are filtered and stored in special tanks;
- Organic waste undergoes composting or are incinerated in special chambers.
Ships like the MSC Euribia and Norwegian Prima already have treatment plants with technology equivalent to that of medium-sized cities, allowing almost 100% of the waste generated is treated or stored sustainably.
Water and waste reuse: circular economy on the high seas
In addition to recycling solid waste, modern ships also adopt practices of water reuse. Equipment of desalination transform seawater into drinking water, reducing the need for refueling in ports.
The water used in showers, sinks and laundries goes through filtration and reuse systems, called gray waters, which can be reused for cleaning common areas or irrigating plants on board.
Another highlight is the use of organic waste to generate thermal energy. On some ships, food waste is dehydrated, turned into pellets and burned to power secondary systems, such as heaters.
Sustainability on the high seas: reports from the environmental team
“Working in the environmental sector of a cruise ship is like being the building manager of a floating neighborhood,” he jokes. Carlos Mendez, head of environmental operations at Royal Caribbean. According to him, the sustainability on the high seas requires discipline and constant monitoring. “We carry out daily internal audits, and all crew receives mandatory training on waste management,” he explains.
Yes, Larissa Coutinho, an environmental engineer who works on the MSC Cruises fleet, highlights the importance of raising awareness among passengers. “Many people think that waste simply disappears, but there is a robust system behind it. And guests are encouraged to collaborate by separating and reducing the use of disposable items,” she says.
Logistical and environmental challenges in an ocean of plastic
Even with the advances, sustainability challenges on cruise ships are still many. One of them is the operational cost of separation and recycling. “The systems are expensive, consume energy and require constant maintenance,” says Larissa.
Also, there are pressure from international organizations and environmentalists about the impact of ships on global warming. Gas emissions, water contamination by sewage and irregular waste disposal are still practices denounced by NGOs in some cases, especially on older ships or less committed operators.
To combat this, leading companies such as MSC, Royal Caribbean and Norwegian have made commitments to the International Maritime Organization (IMO) and developed decarbonization policies by 2050.
Innovations in modern ships: clean energy and cutting-edge recycling
Os new next generation ships are leaving the shipyards with a total focus on sustainability. Among the innovations:
- LNG (liquefied natural gas) powered engines, which reduce emissions by up to 25%;
- In-house recycling plants with robotic waste separation;
- Biodigester systems for processing organic waste no need for incineration;
- Solar panels and lithium batteries to reduce the use of fossil fuels;
- Electrical connection to ports (shore power), allowing the engines to be turned off when docked.
Companies like MSC and Carnival Corporation also invest in big data and AI to optimize resource consumption on board, predicting peaks in energy and water usage.
O cruise ship that generates as much waste as an entire neighborhood — and recycles it all on board is today a symbol of a new paradigm in maritime tourism. Far from being villains of the environment, modern ships are becoming sustainability laboratories, with technologies that could — and should — be replicated in real cities.
The journey towards a cleaner ocean is still underway, but the first steps are already being taken on the high seas — and with much more awareness than one might imagine.
