Duke’s Waikiki has a problem that most restaurants would envy: The longtime restaurant at the Outrigger Waikiki Beach Resort is often packed.

But the high volume of customers also means a high level of food waste, approximately 400 pounds a day, and so Duke’s decided to make an effort toward reducing it.

Six months ago the eatery, which is owned by TS Restaurants, invested in two Ecovim food composters at a cost of $25,000 each.

"Being a busy restaurant, you have to try harder to be more sustainable, to be more green, to be more local," said Duke’s General Manager Dylan Ching. "This was an opportunity where we know we can reduce a lot of waste, this was a way to handle it in bulk, and with partners like Outrigger, we have some means to see if it will work."

The 50-inch-wide, 50-inch-tall stainless-steel composters were purchased from distributor ‘Aina Pono in partnership with Outrigger. They sit in a small outdoor area behind the restaurant’s back door.

Resembling a top-loading washing machine, the machines can compost about 250 pounds of food waste per load during a 13-hour cycle.

Executive chef Keith Kong explained that food scraps from the kitchen and customers’ plates are collected in dozens of small buckets that are brought to the composters. The waste includes everything from salad bar greens to pasta, rice, cooked meat and fish bones. The devices can also handle compostable forks, plates and napkins, but no more than 15 percent of the total mix.

Once sealed inside the composter, the waste is heated to 180 degrees Fahrenheit, agitated to break the food into smaller particles and dehydrated.

What comes out in a tray at bottom is about 25 pounds of sterile, humus-rich soil amendment along with 25 gallons of sanitized water. Installing the machine simply requires a 220-volt outlet and a drain.

Already, the restaurant has seen a 60 percent reduction in food waste, lowering its trash disposal costs.

What still has to be worked out is how to get the compost to local farms, according to Diana Allen, president of ‘Aina Pono, who says she’s working on a solution.

While small amounts could be spread on golf courses or home gardens, a two- to three-month curing process is necessary before the compost could be used by larger-scale farms.

Besides Duke’s Waikiki, Punahou School is using an Ecovim machine for cafeteria food waste as a pilot project. The machines, available in a variety of sizes, also are being used at the Anaheim Convention Center in California and Santa Fe Public Schools in New Mexico, according to Allen.

Honolulu’s Department of Environmental Services estimates restaurants generate about 40 percent of the total food waste on Oahu, more than hotels and grocery stores. Since 1997, larger restaurants have been required by Hono­lulu ordinances to recycle their food waste.

Most hire a contractor to haul the waste to pig farmers or to a recycling facility. That is what Duke’s Wai­kiki continues to do for now.

Ideally, Kong said, the goal is to offer the compost to local farms that supply the restaurant with produce.

"Imagine a chef being able to take his restaurant waste, composting it, getting it to a farmer," he said. "The farmer uses it to grow vegetables, and the vegetables come back (to the kitchen). There’s nothing more exciting for a chef."