Foundational
Coffee waste and by-products
What happens to cherry pulp, husk, parchment, silverskin and spent grounds — cascara, composting, biochar, animal feed and more.
Cherry pulp, husk and parchment
Removed during processing and milling (see CoffeeHQ's seed-to-cup production journey), these organic by-products can be composted, used as fuel, converted to biochar, or (for dried cherry husk specifically) used to make cascara — see CoffeeHQ's cascara guide.
Silverskin
The thin skin released mostly during roasting (as "chaff"); typically a minor waste stream, sometimes explored for use in food products or as a minor biomass fuel source.
Spent coffee grounds
Used grounds from brewing can be composted, used in small amounts as one garden soil input (see the caveats in CoffeeHQ's spent-grounds-as-fertiliser myth entry), or industrially processed into biofuel, and have been explored as a substrate for growing gourmet mushrooms.
Wastewater
Wet processing (depulping, fermentation, washing) produces wastewater high in organic matter; proper treatment is a genuine environmental consideration for wet mills, and untreated discharge is a documented pollution risk in some regions.
Regulatory and safety caveats
Food and cosmetic uses of coffee by-products (like cascara or silverskin-derived products) are subject to normal food-safety regulation in most jurisdictions; garden/composting uses should follow ordinary composting good practice rather than being applied indiscriminately in concentrated, undiluted form.