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Dorseteco's Visit to the Anaerobic Digester, we know how to have a good time.....

Updated: Jun 26, 2023

In October I noticed an invite on Facebook from Litter Free Dorset to visit the Anaerobic digester in Piddle Hinton. I'm interested to see what really happens to our waste primarily the recycling of waste plastics and other products that we put out every other week, but this peaked my interest too. So we replied and were lucky enough to get two spaces.

We had to wear steel toe caps and hi viz jackets but lets face it, waste is all about the glamour, and off we went. There was a group of about 12 people and we had a safety briefing and the tour began. We saw the small domestic truck arriving and being weighed, it then reversed into the large barn area and tipped its load off into an area containing turning screws to push the food waste through the very complicated process. Yes it was rather smelly but manageable and just a composting/off food type of odour, sadly you get used to it quite quickly.

What happens to food waste in Dorset?

All the food waste from across Dorset is processed in this one place. There is a hub where the smaller lorries bring their loads to a larger lorry to be transported across the county in a more efficient way this is near Bournemouth airport somewhere.

At an extremely basic level this food waste is then pushed through the very complicated system, a waste milk product is added (this is the water that is used to wash down dairies, so its a mix of water and milk and would otherwise be a waste product itself) to make the contents more liquid. This was a real shock to me but the compostable bags and any other plastic contaminants are scooped off the top as these do not get processed. These are then separated and are sent off to landfill. The reason for that is that the end product from this system is a fertiliser that is then spread on the fields, which would not benefit from partially composted bags being in it, the food waste we produce from our home collections is not composted so the bags do not get a chance to break down.

I did question whether we should be using the compostable caddy bags at all, and the response was that if it encourages more people to bother to use their food waste bins the council would prefer for them to keep on doing so. It also in reality makes it a cleaner process for the bin operatives to deal with. Basically as long as you are bothering to separate your food waste and to put it out for collection please keep doing so.

After lots of complicated pipe work and testing, small amounts of chemicals are added to ensure the end result has all the nutrients in it needed as a fertiliser. The whole liquid food porridge type of product is then pasteurised at a certain temperature to kill off bacterias such as ecoli and salmonella (I think this was 70 degrees for one hour, but don't quote me on that!). This pasteurised product is then fed through into enormous holding tanks (the size of those old gas tanks you still see up and down the country) which is stirred and this then creates gas which is fed back into the national grid - this is how recycled waste helps to produce energy to power local properties. The final sludge for want of a better word is loaded onto containerised lorries and sent off to be used as fertiliser.

Anybody in the know would be scathing of my recollection but as I said this is a lemans interpretation, and sadly it was so complicated and clever it was hard to keep up with. A fascinating process and well worth the visit, thanks to Litter Free Dorset for inviting us along, next time a visit to the plastic recycling process centre please.

For the real facts visit This is Eco's website

At Christmas and during the Summer we produce the most amounts of food waste, maybe try this year to think about what you throw away, think about how to be more sustainable. Could you freeze it for future use, or bake it or cook it rather than throwing it in the waste caddy. The amount of waste to be processed at these times of year is shocking. See if you can't try and improve your carbon footprint by not buying too much in the first place, perhaps make your own cookies, or sweet treats instead of buying the expensive packaged versions, a win win.

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