First Principles

Home composting is a sustainable way of producing a nutrient rich, organic material that can be reused in your own garden.

Humans have been composting since the beginning of cultivation, around 12,000 years ago. We began to understand that the natural process of decomposition could be sped up if we were careful about the way we combined the materials we used.

The four ingredients for a good compost are brown material (carbon), green material (nitrogen) water and air. The goal is to make an environment where the organisms that break down the organic materials can thrive.

Water and oxygen are crucial to this. Certain organisms can live without air, this is the case with anaerobic decomposition. We try to avoid this process because it's slow, taking around a year to complete. It's also rather smelly as it involves putrefaction. This is what happens when a mound of grass clippings are left to decompose, for example.  

The purpose of carbon and nitrogen is to provide a food source for the organisms to feed from. Just like plants, they require nitrogen and carbon as an energy source. Carbon is also needed to build living cells, and is the reason why it is known as the building block of life. It forms the skeleton, figuratively and literally, making up about 50 percent of the organism's mass.

It's the way it's mixed that counts

How the nitrogen and carbon are mixed together has a major effect on the quality of cold compost results. Both materials come in a variety of forms and each one will need to be added in different ways. For instance, cardboard should be added to a compost heap in a different ratio to fallen leaves, even though both are a source of carbon.

The accepted ratio is 30 to 1: 30 parts carbon to 1 part nitrogen. This is because as a general rule, that's how many atoms of each material microorganisms use for growth.

Even so, this doesn't produce guaranteed results. Many gardeners take a trial an error approach to home composting. With so much to do already in the garden, it's easy to see why many gardeners send their material away in green bins and favour buying ready-made compost instead. 

Heat: the final ingredient

Large compost heaps decompose quickly regardless of the ratios in which material is added. Industrial scale compost facilities with enormous mounds of material can produce an organic product in a fraction of the time it takes most home gardeners to produce a few buckets. But why?

The simple answer is heat. If you have ever dug down to see inside an active compost heap, you will notice how hot they are. This heat is a by-product of the microbial breakdown of the compost material. Larger heaps product a lot of heat, particularly in the centre, which is insulated by the material around it. Retaining this heat keeps the microbes active, so heat becomes a way of measuring activity levels of the microbes, which tells us how quickly they will product organic compost.

The rate of chemical reaction in a compost heap doubles for every 10°C increase in temperature.

This Gardeners' World article recommends your compost heap be at least a cubic meter in size, anything less is unlikely to produce enough heat for a cold composter work. Even so, one still needs to mix the contents again because the outside material doesn't become warm enough to decompose, so we must set about the task of turning it over to put it into the middle.

Is there a way that we can get all the benefits of hot composting without mixing?

HOTBIN to the rescue

HOTBIN is manufactured from expanded polypropylene, a durable and 100% recyclable material, chosen for its unmatched insulation properties. It keeps the bin running at its optimum temperature, retains heat for longer and allows the bacteria to work effectively. 

This means that unlike traditional composting, the HOTBIN maintains heat even to the outermost compost material, which means you never have to mix it.

HOTBIN Composters are designed to operate at a temperature between 40-60°C, making it up to 32 times faster than traditional composting methods.

With typical UK temperatures around 10°C, a standard compost bin will take 12-24 months to compost. The HOTBIN operating at 60°C takes just 12-24 days.

Polypropylene is the same plastic material used to make garden chairs and tables however the key difference is that the material comes in bead form which is then expanded, so the HOTBIN is actually about 98% air.

Benefits of HOTBIN

Making repeated batches of rich organic material is easier with a product like HOTBIN because it maintains a high temperature all year round. It also means it can take a wide variety of materials, including food waste.

The other benefit of high temperatures is that it kills weed seeds. This means fewer viable seeds in the fresh compost you spread. It also kills pathogens and bacteria. At 60°C, it takes an hour to sanitise compost material that contains e-coli and salmonella. Similarly, eggs and larvae are killed and it becomes so hot that pests and vermin cannot tolerate it and go elsewhere.

Herbicides and pesticides can often survive cold composting methods, but HOTBIN has been shown to break them down 32 times faster at 60°C. 

The compost process produces chemical gases but the design of HOTBIN keeps them inside, making it odourless. If you are short on space and need to keep a compost bin near your house, the units are neat and compact and you don't have to worry about bad odours or vermin.

With traditional compost bins, you need to allocate space around it to be used for emptying and mixing the material before putting it back for longer. With HOTBIN, you never need to mix it so it can go in the smallest of spaces.

Kitchen Waste & HOTBIN

While the HOTBIN is used by gardeners everywhere, you don't need to produce garden waste to benefit from HOTBIN. Many people want to dispose of their food waste only, and HOTBIN is the ideal solution. 

Any place that produces food waste, such as canteens, cafeterias or offices and workspaces can use a HOTBIN. If you live in an apartment, a communal HOTBIN is a good way of recycling food waste and producing rich, nutrient packed compost for use in balcony gardens or for house plants.

Typically the bin would be operated at the higher temperature to break down cooked food and small bones.

HOTBIN suggested guidelines:

Add over 40°C: Cooked food waste, meat, fish and bones.

Under 40°C: Vegetable peelings, offcuts and fruit peelings (including citrus), tea leaves, coffee grinds, nuts.

Adding food waste will produce a quick rise in the HOTBIN temperature, but it will also drop off more quickly than garden waste. To help things to stay warm, just add some materials that are harder to digest. The HOTBIN bulking agent is ideal for this.

If you compost smaller amounts of food, the 100 litre HOTBIN Mini will be easier to keep at hot composting temperatures. After a while you will get to know your temperature peaks and troughs and this will give you a good idea of when to feed it.

Making sure that the material added to the bin is chopped, really helps keep things digesting. Top up with some bulking agent or shredded paper to keep the ratios about right and to ensure air pockets form to allow the bacteria to thrive.

Food waste is considered "wet" so you may need to add some extra paper to control moisture levels.

A bonus cup of tea (leachate)

HOTBIN has a drain feature at the base of the unit that allows you to drain off the liquid that your compost material produces. This brown, odourless liquid is called leachate and can be used in your garden as a natural fertiliser. 

To make collection easier, Frankton's recommends the corresponding HOTBIN Plinth, which makes collection of this valuable product much easier.

Leachate is shown to stimulate plant growth by improving the uptake of minerals. You can expect up to a mug full (300ml) when draining regularly but it may vary based on the types of waste added to the HOTBIN.

To use the leachate, follow these simple rules:

• Wear gloves when draining.
• Use collected leachate within a 2-week period
• Before using, dilute the leachate at a ratio of 1:10 (1 part leachate to 10 parts water). This becomes the liquid fertiliser.
• Pour the liquid fertiliser on to the soil around plants; avoid wetting or spraying any foliage
• When growing edibles, thoroughly wash edible items that you feed with compost, fertiliser and or leachate, especially uncooked items.

If the material in your HOTBIN is too wet, it will produce a different liquid, which is yellow in colour with a fruity aroma. It isn't suitable for your plants and can be discarded. A compost that is too wet needs absorbent material added to it, such as shredded paper.

A black sticky liquid that is pungent in smell indicates that the HOTBIN is anaerobic. This is when the material is too dense and oxygen is excluded. Pure grass clippings, for example. Again, it isn't suitable for use elsewhere and can be discarded.