MORI ROTHMAN:

Sujin Woo and her mother, Lee Bo-ok live in an apartment in South Korea's capital of Seoul. On this Saturday morning, Lee is making Korean fried sweet potatoes for lunch.

Some parts of the food, like the sweet potato peels, won't make the final dish, but instead of tossing them in the trash, Lee places the food waste in this special container. In South Korea, separating food waste from the rest of your garbage is required by law…and anyone who doesn't recycle food waste faces potential fines.

Seoul's 10 million residents started paying for their food waste by weight in 2013….a policy now in 16 other cities and provinces. Woo disposes of the food waste in bags bought from the city and tracks her food waste with a radio frequency ID card. Woo taps the card to register the household and dumps her food waste into the bin, which logs how much waste she'll be charged for.