Nutrient recovery and reuse is all about the way we use the materials, like food and water, that we have in nature. It's about finding ways to save these valuable resources, so that nothing goes to waste. For example, when we eat food, we put the remains, like peels, stems, and leaves, in the trash. But with nutrient recovery and reuse, we can turn these remains into something else, like compost to help things grow better. We can also filter and clean water that is used for drinking, bathing, and cleaning and reuse it for other things. This helps us to not use up clean water too quickly and keep our environment healthy.