All major cruise operators go to great lengths to highlight their waste mitigation efforts. Globally, around one third of food produced for human consumption goes to waste. With lavish buffet-style dining currently being a key part of the cruise experience, the risk of excess is high. “We are able to identify the proper food quantities required, based on a number of factors including prior guest history and occupancy,” says a source at Norwegian Cruise Line, some of whose ships, such as the 4,000-passenger Norwegian Bliss, are among the world’s largest. “The provision master works in conjunction with the food and beverage director and our corporate team to ensure we are sourcing and receiving the appropriate supplies and quantities for each cruise.”

Carnival’s Costa Cruises has pledged to reduce food waste by 50% fleetwide by 2020, with the help of tech company Winnow and its system which weighs and records what kitchens throw away. In their annual environmental reports, cruise operators like to emphasize how much investment has gone into waste management and waste recycling and repurposing. “There are significant improvements compared to the situation 15 years ago,” says Konstantin Tchetchine, general manager, business development, marine solutions/water and waste at Wärtsilä, a Finnish company that provides waste management technology for the shipping industry. “For example, cruise ships recycle about 60% more waste per person than the average person recycles on shore. Still, the ship owners and ship operators are facing many challenges,” he adds.

A ship with 6,000 people on board can generate around 2,100 tons of waste water, 24 tons of wet waste (food waste and bio sludge from waste water treatment plants) and 14 tons of dry waste per day (solid burnable waste, plastic, glass, tins and cans). All this waste altogether is enough to fill around 110 trucks. Each of these three main types of waste can itself be further categorized into multiple other waste categories, each requiring its own treatment.

Waste water comprises black water, from toilets, gray water from showers, galleys and laundry, as well as bilge waters, that have gone through the engine room and been exposed to oil and chemicals. Ships must have processes in place to treat each of these. Wet waste is, in turn, de-watered and dried. This reduces its volume considerably and it is then stored in a silo. From there it can be conveyed into an incinerator for burning, or to a bagging station prior to discharge to land facilities after docking in port.

Dry waste is divided before treatment into burnable, non-burnable and recyclable items. Then, depending on the material (plastic, aluminum, glass and so on), it’s either shredded or compacted, again with the goal of reducing the space it takes up. In summary, the whole waste treatment infrastructure required by a large cruise ship is nothing short of that of a small city. The operation of these floating behemoths involves some rather extravagant figures.

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