Springhill Composter

.....at Springhill Co-housing, Stroud.

Food waste composters.

These were created to compost cooked food waste, from the households in the Co-housing community.

The process being developed here is to layer the food waste with garden waste: as a compost lasagne.....!!

Guidelines:

■ Springhill composter can compost all food waste. 

■ Food waste is mixed with some other materials known as the ‘browns’ (see below).

■ It gets hot from ‘thermophilic’ (heat loving/emitting) bacteria*, which means it composts fast.

■ A layer of garden waste is regularly placed over the food waste.

Composting works best with a diversity of inputs. This gives a range of nutrients for living things, and a balance of carbon, nitrogen and other nutrients. This can be likened to our need for a balanced diet of roughage (fibrous), with energy (carbohydrates, carbon and hydrogen rich) with protein (nitrogen rich).
In the composting process, the carbon rich materials (known as the 'browns') supply energy to organisms.They also provide fibrous 'structure' which facilitates air movement, and their absorbtive surfaces take up the moisture of sappy and water rich materials.

Thus composting works better with both cooked and raw food,

● Raw food

● Cooked food

Raw food

Eg.:

- Peelings

- Gone-off fruit and veg

- Max lump size: 1 inch

  (chop if larger)

Cooked food

 includes

● Stale bread (broken up)

● Coffee grounds

● Tea bags

Add equal volume of ‘browns’ to food waste

‘Browns’ :  

(high in carbon, dry, fibrous)

-         Torn-up cardboard

-         Torn cereal-type boxes (ie. un-laminated card)

-         Egg boxes

-         Shredded paper

-         Torn newspaper (thin strips)

-         Autumn leaves,

-         Straw, hay

Lasagna !

Alternating layers of food waste 5 cm thick

and garden waste 10 cm thick

Garden waste:

● Weeds

● Leaves

No thick twigs !

* Thermophilic bacteria

These bacteria exist as spores, a dried out, dormant, seed like form, in which they can last for possibly thousands, maybe millions of years !
They are just about everywhere on the earth. When the conditions are right, they 'wake' up, and start respiring, feeding and reproducing again. They just need the right levels of water, food and temperature.
Alongside these bacteria are many other bacteria species, and fungi, and invertebrates such as woodlice which feed on organic matter.
All living things release heat as they respire but of they are contained within enough organic matter (a volume of around 1cubic metre is ideal), the heat created cannot escape very fast and the temperature rises. Organic processes speed up. But this tempeature kills most things as it climbs over 60C, except for the thermophilic bacteria, which can survive over 70C. Thus they keep going until they too die off due to overheating, and use up the food supplies. Thus the temperature drops again, and other living processes move back in to finish of the decomposition.

That is a model of what happens, anyway, as I have understood it !

Garden waste provides  fibrous carbon and has air spaces enabling aerobic decomposition.

Garden waste is placed in a layer over the food waste:   It reduces flies and smells.

 

Garden waste forming current top layer.

As you may be able to tell, the nearer composter is made from a 4-wheel wheelie bin !
It was converted by creating:
- A hatch at the bottom for harvesting compost and for inspection.
- Drainage holes and air holes, all rat proofed with weld mesh wire.
- A moisture liner - which is a piece of pond liner attached to the inside of the lid,
  so it flops down onto the waste. You can see it hanging down at the back.
   This was found to be needed, as the warmth of the composting, meant that it was drying out too much.
- A housing of wood, for insulation and aesthetics, made from 'ship lap' fencing.
- Green corrugated felt lid on top for aesthetics and insulation.

 

The two composters.

The removable wooden hatch of the right hand one will be improved for aesthetics
and ease of opening..



 
Hatch at the bottom,
and liquid collection for use as a plant feed.
It is planned to add a pipe that takes the liquid to a container,
without the need to remove the hatch door.

 Platform for standing on in order to
    reach in and add material.


Further planned improvements:
- a pipe to bring the liquid out to a container
- the hatch of the right hand composter to be replaced with ship lap timber,
for easier removal and better appearance.
- a moisture liner inside lid to be added to left hand composter