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Can I compost egg shells and eggs?


You have missed the box of eggs in the back of the fridge – they are 3 weeks past the USE BY date – you are not going to eat them… what do you do with them?

Here is the HOTBIN composting ‘egghaustive’ review of the topic!

Let’s agree we are going to gently chastise ourselves, plan better and monitor the fridge more often so it does not happen again. Maybe next time we buy too many and it looks like we are going to have wastage, we can arrange a “Bake OFF” with the children….

But right now that still leaves us with a box eggs unfit to eat –

  • We could chuck box and eggs in the waste bin and they will go off to landfill
  • We could crack them open, tip the egg down sink and put the shells in the compost bin (messy!)
  • OR In a HOTBIN – we could just crack the eggs into the bin and compost them.

Are we sure – yes – the eggs are just protein and water.

As long as your bin is working between 40-60C, and you add some shredded paper and bulking agent (as normal with food waste) the egg and yolk will be broken down and ‘invisible’ within a few days. The shells will take a lot longer – but all that calcium carbonate in the shell will go back into the soil it’s just a version of ‘lime’ for gardeners.

OCD HOTBIN users, sad but true…

We do know at least one person has fried an egg inside the HOTBIN composter – we stress this was more out of inquisitiveness than with any intent to eat the fried egg!

Did you know 1:  in the UK we eat 32 million eggs a day, a staggering 11 billion eggs every year. Over 85 per cent of these are produced domestically by 29 million laying hens each laying an average of 314 eggs each. (source: British Egg Information Service, website).

Did you know 2:  The UK throws out an estimated 19,000 tonnes of eggs a year, costing us about £60 million pounds (WRAP – the food we waste, 2011). The average egg weighs 40g, so we have 25 eggs per Kg, 25,000 eggs per tonne, or 475 million eggs thrown out a year.

There are ~30 million UK homes, so on average, each household throws out ‘a dozen eggs a year’.

Cross check – an egg costs 14p, £0.14 X 475 m eggs =  £66 million = WRAP figure

Please note our first paragraph – we are not suggesting composting eggs is a good thing – your goal should be to avoid wasting them and any food. Given that accidents happen – sending eggs to landfill does not seem a positive step.

Please let us know if you have more creative options for what to do.

Did you know 3: Although we are not sure how accurate this is in terms of H&S aspects like listeria: you can test an egg and get an approximation of its age by gently dropping the egg into a bowl of cold water:

  • sinks to the bottom and stays there, it is about three to six days old.
  • Sinks, but floats at an angle, it’s more than a week old.
  • Sinks, but then stands on end, it’s about two weeks old.
  • Floats, it’s too old and should be discarded.

If it sinks, it’s good; if it floats, it’s too old.

Eggs act this way in water because of the air sac present in all eggs. As the egg ages, the air sac gets larger because the egg shell is a semi-permeable membrane. The air sac, when large enough, makes the egg float. Eggs are generally good for about three weeks after you buy them – and this should be the USE BY date – the red stamp date on the egg.

Did you know 4: to test if your egg is hard boiled, spin it on a flat surface. If the egg wobbles, it’s fresh because the insides are moving around. If the egg spins smoothly, it’s cooked.

I think we have now ‘egghausted’ this topic! But if you have a HOTBIN that is HOT COMPOSTING you can COMPOST out of date eggs!

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