Used ground coffee can be reused or recycled for various purposes, such as gardening, cleaning, or beauty. Some of the ways you can reuse or recycle your used ground coffee are: 1) Use them as a fertilizer or compost for your plants, as they provide nitrogen and other nutrients to the soil. 2) Use them as a natural scrub or mask for your skin, as they exfoliate and moisturize your skin. 3) Use them as a deodorizer or cleaner for your home, as they absorb odors and stains from various surfaces.