Our next-but-one neighbours are on the move and asked if I could empty their plastic compost-bin. They wanted to take the bin with them but did not want the hassle of bagging up the contents and transporting them to their new home. The compost-bin was a standard recycled plastic unit often sold through local authorities.
The bin was about 15 years old and in good nick apart from a bit of damage around the upper rim. Only kitchen scraps/peelings had been added along with some paper/card/egg boxes. Finished compost was extracted from the hatch at the bottom to make space for more kitchen scraps at the top. I have used these bins in the past and found them OK, if not brilliant, although I was filling my bins with a mixture of kitchen and garden waste.
The base of the bin was well-bedded into the surrounding soil and it didn't look like the hatch had been opened in a while. On removing the lid, I found a 'family' of leopard slugs (aka great grey slugs) clinging to the lid which I carefully put to one side.
The top 10 centimetres of the compost heap was full of worms and fresh kitchen waste. I scooped this up and transferred it to my active HotBin© while rescuing as many worms as I could.
The layer below was remarkably compost-like but with quite a bit of still-identifiable organic matter such as Avocado skins and egg shells along with teabags and 'compostable' bin liners. Bits of plastic (e.g. garden centre plant labels), paper (labels?) and pottery (plant pot crocks?) were found throughout the heap. The bottom half of the bin was predominantly good quality homemade compost with egg shells and the occasional unidentified object. A teaspoon and a fork were also recovered and returned to the owner.
After sieving all but the top 10 centimetres to separate the usable compost from partially-composted or non-compostable material, the former was bagged up for garden use and the latter disposed of via general waste.
Compost:
The yield of good-quality compost was around 300 L and the waste was about 80 L. All this from a 330 L compost-bin! Note, in the picture below, one bag of sieved compost has already been returned to my neighbour as a thank you.
I was pleasantly surprised by the quality and quantity of usable compost extracted from the bin. By feeding what is essentially a large wormery with easily compostable kitchen scraps, this cold-composting process works well. I asked my neighbour how old she thought the oldest compost (at the bottom) was and she guessed a year. I suspect it is much older than that, probably 2 to 3 years old at least. Assuming a two-person household produces about 6 litres of kitchen waste per week then it would take a full year to fill the 330 L bin without any decomposition and compaction. However, there is a 5- to 10-fold volume reduction due to the composting process which could make parts of this particular compost heap over 5 years old.
The compost is already being used to give my chitted seed potatoes and onion sets a good start, for top dressing outside flower pots and preparing potting compost by adding coir and/or perlite.
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