Category Archives: Composting kitchen waste

Emptying the HotBin composter

The HotBin Mk1 compost bin was emptied yesterday. It had been used for composting food waste starting on 29 May 2020. A total of 78.85Kg of food preparation waste plus tea bags, coffee grounds and a small amount of cooked food had been added approximately every 2 weeks. Shredded paper and wood chips, to balance the C:N ratio and occasionally a couple of hands full of grass cuttings were also used to get things going.

That is not the ideal way to manage a HotBin, the makers say add 2.5Kg – 5 Kg weekly not the 10Kg-15Kg every 14-18 days that I had been doing. Although the contents were heating to 40C to 60C and the material composted quickly the temperature dropped when all the fuel was used. They are right of course, to keep the contents at an even hot temperature it is better to add a less material regularly and that is what I will be doing in future.

This is what I found when I removed the lid

Having admitted that I was not following the instructions how did it all work out? The overwhelming answer is very well! As I have kept records of how much and what went into the bin from 29 May to 8 October I know there that 78.85Kg was added and 63Kg of compost was produced, two good wheel barrows full! That’s 86.5% of the material added.

Now I call that a pretty good result especially as compost made with  food waste is rich in nutrients and it has inspired a new project!

The first few spades full removed from the bin

Compost worms at work in the top layer

The new Mk2 bin installed and waiting to be filled

First job is to install a new MK2 HotBin. It should be up and running in the next few days. The next part of the project is to clean out the old HotBin and reduce the amount of ventilation by blocking off the extra holes I drilled earlier in the year. After that it will be on a paving slab beside the new bin so the two can be run together.

I have been asked why I bother to compost kitchen waste when we have weekly collections by the local council. First, I do not want to give away such a valuable source of compostable material. Second, the aim is to make the house and garden as near zero waste as possible. In practice it means continually thinking about how we can reduce the amount of waste coming in and recycling everything we can.

See more here:
Composting kitchen waste
Composting kitchen waste updates January 2013
Composting kitchen waste trial – 6 years on

The usual disclaimer, we no associations with HotBin other than being satisfied customers.

We are running an online composting workshop on Thursday 22nd October, see further information here.

Council compost bins

To encourage more home composting councils are offering discounted compost bins, you can check here to see if your council is part of the scheme. In Derbyshire we can get a 220-litre Blackwall compost convertor for £19 and the 330-litre size for £21 plus a delivery charge of £5.99. When you consider that our district council will be charging £50 a year for emptying the green bin it makes sense to start composting your garden waste.

I ordered the 330-litre bin which was delivered in a couple of days. I wanted to see how easy it was to use and how well it worked. The first fill was a mixture of grass cutting and shredded garden waste.

Measuring the temperature is a good was to check if the bin is working. A hole was drilled to allow the use of a standard compost thermometer. To reach and maintain 60c means that the bin is working well.

Day      Temp
1            23C
2            43C
3            61C
4            61C

If you want to know how to make hot compost go to this page.

We will be running a series of online composting workshops beginning in late September 2020
please email us for details

Compost bin water heater

Now this is an idea I really like especially as our local council say they are withdrawing green bins next year. Well, not actually taking them away but only emptying them if you pay.

From: Permaculture News, see link below

This is an ideal to make them into compost bins and get hot water. It’s not new idea but this looks interesting. I can see a row of them with isolating valves so that they can be switched on when hot and off as they cool down.

Not sure what the effect would be on the compost, first thoughts are that if you remove heat you slow down the process. I would guess that it depends on how much heat is taken.

It could be another crazy project for next year! Full text of the article is here. (You need to scroll down the page.)

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Composting food waste reduces greenhouse gas emissions

There is a relatively easy way for a council, municipal authority or government to do something effective for the environment, compost food waste. Why is it so important? Because if food waste waste were a country it would be the third highest emitter of green house gases next to China and the US.

In the UK; “Of the 10 million tonnes of food waste arising annually in the UK, only 1.8 million tonnes is currently recycled (either by composting or anaerobic digestion). Only 12% of household food waste collected by local authorities is recycled, with the remaining 88% ending up in the residual waste stream.” (WRAP)

In 2013 we got a HotBin.  See an article by Alys Fowler in The Guardian here. All of our food preparation waste goes into the bin, that is around around 200Kg a year. It has worked ever since, even in the coldest winters. All the compost it produced goes back onto the veg garden.

The usual disclaimer, we are not associated with the company that sells the bins, just a satisfied user!

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Large scale windrow composting

Watch the fascinating video from the US to see how commercial compost is made on a large scale. There are other methods especially for food waste where it happens ‘in vessel’ to ensure that all pathogens are killed and to reduce odours.

Compost locks up atmospheric carbon in soil. Healthy soils grow healthy food.

Just make compost to save the world

In metric measure that means every cubic metre of compost made sequesters 400kg of CO2. Think about that, just the simple task of composting kitchen and garden waste reduces the amount of CO2 in the atmosphere. This is from a Facebook post by A1 Organics who are based in Colorado. Check out International Compost Awareness Week for more information.

Compost makes soil that can be used to grow food at home which eliminates food miles further reducing your carbon footprint. There are lots more benefits, homegrown food picked as it is needed is more nutritious and gardening improves general health.

My final plea is to grow your food without chemical pesticides and fertilisers. If you make good compost you don’t need them.

Hotbin update

After clearing out then HotBin Mk1 food composter a few days back I made a modification to increase the airflow through the bin. It was clear that as the bin filled up the airflow became restricted. The answer was to add a perforated plastic pipe in the back right corner.

The pipe was an odd length of scrap plastic pipe from an old milking parlour. It had a right angle bend glued to one end which was cut off to leave a short length of pipe and then the stub of the bend. This allowed it to be pushed through a hole cut in the floor enough to reach the space below without falling through the hole. I also made another air inlet on the back of space between the removable floor and the base of the bin.

The bin is now standing on wood to allow any liquid to drain through holes in the base. I added dry twigs to the floor to enable air to come through and to try and prevent the ventilation hole being blocked.

Yesterday I added the first contents which was about a week of food prep scraps, tea bags and coffee grounds. There was also some shredded paper (mainly brown) and shredded dry garden waste as a bulking agent. Finally, the contents were mixed and watered a to get the wrung out sponge wetness.

Today, just 24 hours after starting the bin, the contents are at 45C. The air flow control valve was just open; when fully open it was easy to feel the how air coming through the bin. So far so good, it looks as if the modification has worked well. It will be interesting to see what happens as the bin fills up.

Update 31 May 2020
The modified HotBin has been in use for a few weeks now and is working very well. The latest batch of compost was added a couple of days ago and heated to 57C on the second day. It was the usual mix of about 4.8Kg of kitchen prep waste, a couple of hand fulls of my bulking agent, same again of grass cuttings and three hand fulls shredded brown paper. It was well mixed and watered.

I still need to replace the charcoal filter and block the extra hole cut in the bottom chamber as I think there is too much airflow.

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A step-by-step guide to composting garden waste

In many parts of the country local authorities are suspending the collection of garden waste due to staff shortages. As the situation could go on for several more weeks it is important to know what to do with your garden waste. The answer is simple – MAKE COMPOST!

It need not cost you anything as you can make a compost heap in your garden. If you already have a compost bin, then clean it out and start afresh. In many parts of the country local councils are sponsoring the purchase of compost bins so check before you buy one.

If you live in Derbyshire see this page for more information on offers of compost bins and water butts.

Other local authorities have similar schemes so check before you buy.

If you don’t have a bin you can still make compost by finding a convenient corner of the garden to make a heap with a waterproof cover to keep out the rain

Whether you are making a heap or bin the steps are the same.

  1. Find a site for your bin or pile on grass or soil. It’s better to be out of full sun as it will dry out the contents. The heat in hot composting comes for the action of the bacteria as they breakdown the contents and not from the sun.
  2. Gather together the stuff you want to compost; it’s best to have enough materials to make a complete batch or bin full, if not, you can start with around half that. Aim for at least half a cubic metre.
  3. Only add material in batches and do not just throw stuff in when you find it but save it until you have enough.
  4. Sort it into two groups – browns and greens:

    Browns
    • Autumn leaves
    • Pine needles
    • Twigs, chipped tree branches/bark
    • Straw or hay
    • Sawdust
    • Paper, brown paper is best like that used in packing from Amazon etc.
    • Plain cardboard, not printed, toilet roll inners, egg boxes tear up into small pieces and limit the amount you put in the bin. Use to balance the greens and browns and not as an alternative to recycling.

Greens

    • Grass clippings
    • Coffee grounds/tea bags (check the bags are fully compostable and do not include plastic)
    • Vegetable and fruit peelings
    • Trimmings from perennial and annual plants
    • Weeds but do not include any with seeds if your bin/heap does not get hot
    • Animal manures but not from dogs or cats

Not worth adding/be careful

    • Egg shells – they will never break down because they are made of calcium carbonate (CaCO3) crystals. They cannot add calcium to the compost or to the soil.
    • Food waste unless you know the bin will heat up. You can add it to the centre of a hot heap/pile but it is best composted in a separate container such as a HotBin.
  1. Getting the correct balance of greens and browns will help the compost to heat up. A good rule of thumb is to use two buckets of greens to one bucket of browns as you add material to your heap/bin.
  2. Be sure to mix the contents well as you add them especially grass clippings as they tend to stick together in lumps, break them up!
  3. The next step is to wet the mixture, not totally soaked, more like a wrung-out sponge.
  4. Cover an open pile with waterproof sheet or put the lid on you bin. After a few days the contents should heat up.
  5. After a while the contents will start to cool down and will have shrunk. You might see that material around the edges has not composted as well as that in the centre. Now is the time to turn the pile/contents of the bin. What this means is taking everything out and then putting it back in. It helps if you ‘fluff up the contents’ to add more air. You might also need to add some more water if it feels it is dry. Again, not a soaking but more like a wrung out sponge.
  6. After a few days the heap/bin should start to heat up again, but it may not get as hot as before. It will eventually start to cool down and you could try turning again or just leave it.
  7. Hot composting should be complete in 8-10 weeks and will take another couple of months to mature. It is ready to use on the garden when it looks like and smells like the forest floor.

If you would like more information about composting then please take a look at
our other pages.

If you need help with your composting please email us HERE

Please send us your photos, comments and short videos of your compost and we will share them here.

(Last update 08 Apr 2020)