6 ways to recycle your coffee grounds at home

World coffee consumption is enormous, with over 820 billion cups of coffee drunk every year, around 100 cups each for all 7.98 billion people. That’s an awful lot of leftover coffee, estimated to be 250,000 tonnes in the UK and nearly 6 million tonnes globally. Coffee waste sent to landfill contributes to methane greenhouse gas emissions and if it’s washed down the sink can contribute to blocked drains and sewers, needing to be cleaned up before going to landfill. The good news is that used coffee grounds still retain many of the chemical compounds from the raw bean. These coffee grounds are a resource that can be used and are increasingly being recycled to extract more benefits from the coffee crop, after being consumed by millions for the pleasure of a hot caffeinated drink with benefits including antioxidants. Coffee grounds from industry and commercial uses are being collected for processing as a bulk raw material which can be used to replace synthetic and oil-based elements in plastics, cosmetics, textiles and other materials. Business is also processing waste coffee as fire briquettes, as when dried and compressed coffee has a higher calorific value than conventional firewood. Used coffee grounds can also be recycled at home and this helps reduce the amount of used coffee washed down the sink or going to landfill. Scoof is the ideal tool to collect waste coffee from cafetieres and French presses and it makes an excellent accessory when making the coffee too as a stirrer.

Here are some of the most popular ways of recycling your coffee at home:

1. Easiest and simplest: Adding coffee to the compost

Collecting coffee and putting it in the food waste bin is a good way to ensure that it does not go to landfill or adds to the material clogging sinks, drains and sewers. In the UK councils that collect food waste will process it into compost, farm fertiliser or converted into and biogas fuel via anaerobic digestion. If you have a garden, coffee grounds are a useful woody component to add to a compost heap in addition to the food peelings, grass cuttings and garden pruning’s. For active gardeners, making your own compost has 3 core benefits; a free resource to improve the drainage and nutrient health of the soil; a habitat for the creatures that breakdown organic matter into soil; reducing the amount of waste going to landfill In addition, coffee grounds are nitrogen rich and adds nitrogen to the compost, which in turn adds improves the nitrogen content of the soil when applied to beds and planters.

2. For keen gardeners and planters: coffee as a fertiliser for acid loving plants?

Some gardeners add coffee grounds directly to the soil around acid loving plants and in particular acid loving-plants such as ferns, hydrangeas, camelias, rosemary, daffodil, nasturtiums, blackcurrant. Whilst coffee is acidic, once it has been consumed as coffee, most of the acidity has been washed out and the resulting waste grounds are pH neutral. In theory, used coffee grounds should not affect the pH level of the soil, although in practice some gardeners may find that adding used coffee works!

3. For natural, pesticide-free gardeners: A snail and slug repellent

Coffee grounds are rough and woody and some gardeners use this roughness as a deterrent to slugs and snails by sprinkling generous handfuls around plants they wish to protect. For those who choose to be chemical-free, coffee grounds are an easy, cost-free alternative, however, how effective coffee grounds are at deterring snails and slugs is questionable… but perhaps worth a go, depending on how desperate you are to deal with the problem.

4. Growing mushrooms on coffee; as an experiment/ a children’s activity/ or for gourmets

Coffee grounds, once used to make coffee are a clean, neutral pH, nutrient-rich soil that can be used for growing mushrooms – not just any mushrooms, but delicious ones you can add to an omelette! There are kits that you can buy to grow mushrooms, often in old logs, cardboard, sawdust or coffee that has been impregnated with mushroom spawn. It’s possible to make your own kit with your collected used coffee, a suitable container and a bit of trial and error. You will need to purchase some mushroom spawn and there are many suppliers to be found online. The easiest variety to grow at home are oyster mushrooms and the here are the steps to planting your first crop:

Decide the size of your crop: A ratio of 5 parts used coffee grounds to 1 part spawn is ideal. Starting with a smaller amount to begin with to develop your growing skills and know-how Purchase your oyster mushroom spawn: there are many suppliers who will send you spawn by post Collecting your grounds: keep your waste coffee in a sealed container and keep in the fridge until you have collected the desired amount Your waste coffee will be a nutrient-rich soil in which to grow your mushrooms. By adding hot water to the coffee, it has already been pasteurised and any microorganisms that may compete with the mushroom mycelium will have been eliminated. However, if the waste coffee has been stored for several days in the fridge, ensure that all the grounds are pasteurised by adding hot water again and then draining to leave a moist soil of coffee grounds

Inoculate the coffee grounds: take a clean plastic container with a sealable lid (an old food carton is ideal as aeration holes are required in the lid). Cut 4-5 ½ cm diameter holes in the sides. Put the used coffee in a clean mixing bowl and evenly mix in the spawn with clean hands. Transfer to the prepared plastic container and seal it with the lid. Place the container in a warm, dark place (65– 76°F, 18 – 25°C). An airing cupboard is ideal or a similarly warm, dark spot. Inspect over 3 weeks: during this time the spawn will start to develop and will spread across the coffee grounds, forming a carpet of white mycelium Fruiting stage: after 3 weeks the coffee grounds should look completely white – any green spots will be competitor mould (this needs to be carefully removed). If these spots are allowed to grow extensively, they will inhibit mushroom growth and the batch may need discarding and starting again. At the fruiting stage the mushrooms need air and shaded light. Ready the container for the mushrooms to grow by cutting a hole 4-6cm2. Spray with water twice a day to maintain a moist or humid environment for the mushrooms to grow in Ripening: after a week small mushrooms the size of pins will start to form. These will grow rapidly, doubling in size each day for the next week. These are now ready to pick and are ready for cooking.  

5. A beauty treatment: used coffee is an ingredient in facial scrubs

In the world of beauty science coffee has a number of benefits that make it suitable as a facial scrub. To begin with, It is a natural product that is granular and so can act as a gentle abrasive when combined with a suitable lubricant (olive oil, coconut oil, moisturiser, yoghurt etc). There are some further skin benefits claimed for coffee grounds and these include: as an anti-inflammatory; protection from UV rays; increasing production of elastin/collagen and improving skin appearance, and finally caffeine improving the appearance of wrinkles. It is worth noting that this is ‘beauty science’ and whether there are skin benefits is, like beauty, very in the eye of the beholder!

6. Making coffee fire logs: a challenge/ for fun/ an inefficient alternative to solid fuel

Coffee has a high calorific value and can burn hotter and longer than conventional firewood logs. Coffee logs can be bought commercially as a sustainable alternative to wood or charcoal.

Coffee logs can also be made at home… but doing so is probably too impractical/ uneconomic to be an alternative to commercially available coffee logs. In addition to lots of used coffee (freely available from coffee shops), you will need a binder and an agent to aid combustion (recipes generally suggest a combination of molasses and wax). The method involves drying the coffee in an oven, then melting/combining the molasses and wax in an old bread tin (again in the oven), mixing in the coffee grounds and as the mixture cools, pressure needs to be applied to compress into a brick. Finally, the brick needs to be placed in the freezer to be fully set – after about an hour the brick is ready to go on the fire or wood burner.

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