It has traditionally been assumed that these by-products -- coffee grounds and coffee silverskin, have few practical uses and applications. Spent coffee grounds are sometimes employed as homemade skin exfoliants or as abrasive cleaning products. They are also known to make great composting agents for fertilizing certain plants. But apart from these limited applications, coffee by-products are by and large deemed to be virtually useless. As such, practically all of this highly contaminating "coffee waste" ends up in landfills across the globe and has a considerable knock-on effect on the environment.