Category Archives: In the news

Is your HOTBIN compost good, bad or fabulous?

We do not know the answer – only detailed testing will prove things one way or another.

What we do know is this – composts differ in physical structure and chemical composition. HOTBIN compost often appears much wetter and sticker than other composts. We believe some composts will be better for soil fertility than others. We believe those with higher humus content will be better for your soil and hence plants and vegetables.

We have a some evidence it might be better. This is related to the physical properties which in turn we believe are linked to higher humeric substance content.

Humeric substances are the essential component in compost that delivers the benefits – the more humeric substances in your compost the better your compost. It also is the case that the more humeric substances in your soil the more fertile your soil.

To explore if composts are different, we can look at the analysis of composts.

Ask a gardening expert to describe good compost and you may well get a list like this:

  • It smells earthy (not putrid, acrid or drain like?)
  • It is fine particles with no sign of original waste or big bits
  • It is a dark brown material

Some might add a footnote that peat is not compost, farm manure is not compost and that the term ‘humus’ is better reserved to describe ‘very well matured compost’.

Ask a worm composter (vermicomposter) what good compost is and they will probably say:

  • Worm cast / vermicompost is the best compost
  • It smells earthy
  • It is always fine particles with no sign of original waste or big bits
  • It is dark brown
  • It is ‘extra good’ as the worms leave a sticky mucus (from digestion tract) in the compost that promotes mycorrhizal root zone activity

Ask an industrial compost maker and you should get the following:

  • It meets the PAS 100 standard
  • The C / N ratio has been tested and is within spec for “stable and mature” compost
  • It all passes through a given mesh sieve (ie below 8mm particles)
  • All potentially toxic elements (e.g. mercury, heavy metals) are below the guideline levels
  • NKP will be present, but compost is a soil amendment not an NKP fertiliser, so we only measure them in some compost formulations.

Ask a soil scientist to describe compost and they will struggle!

It has no scientific definition – they will refer to “Soil Organic Matter” (SOM). This is the total sum of all dead plant and animal matter in the soil – it excludes roots, living plants, living worms and bugs). They measure the labile part (compostable to you and me) fraction and the non-labile fraction (the bit that resists further decay and is known as the humeric substances fraction. They will then offer you +10 soil types, each with a different ratio of sand, clay and SOM.

The ‘fertile soils’ (what gardeners want) typically will have:

  • SOM of 2-10% (UK norm 2-4%)
  • Within this, humeric substance content of 1-5% (i.e. 50% total SOM)
  • A fertile soil is a balanced mix of SOM, sand (silica) and clays

What if you Googled ‘best compost‘, or ‘the world’s best compost‘?

  • There are claims and methods that profess to offer “colloidal compost”.
  • There are methods such as Luebke, CMS, biodynamic and QR that all purport to make fabulous compost

And what if we ask the HOTBIN expert (Tony Callaghan, head of R&D at HOTBIN) to describe good HOTBIN compost!

  • It smells earthy (not putrid or drain like)
  • It is fine particles with no sign of original waste or big bits
  • It is a dark brown material
  • It is very wet and sticky – so much so it appears ‘large and lumpy’ – but looks can be deceptive – for more information see the FAQ on sieving compost.
  • When dried, about 80% will pass through an 8mm sieve, 5% will be oversize (too large) and 15% will be 0.5-1cm pieces of wood chip (bulking agent) coated in humus.
  • It will be pliable i.e. show signs of high levels of colloidal humeric substances
  • The C/N ratio will be in the “stable and mature” zone (when tested using the Solvita compost test kit)

We have found no definition or standard that can be laboratory tested for a good, bad or fabulous compost. Only tests for ”stable and mature compost’. There is no system that routinely tracks ’cause and effect’ for any difference in compost quality directly back to a composting method.

The question remains: can one compost method deliver better compost than another?

There is ample scientific evidence that nature’s composting (i.e. on/in the soils) does produce different levels of residual humeric substances – varying from 0 and 3% depending on a range of conditions (soil structure, temp, water, oxygen).

The HOTBIN is composting outside the soil environment. The HOTBIN (subject to correct operating practice) offers a degree of control and conditions not often encountered in most soils or even most compost bins!

Does the HOTBIN deliver a better, richer compost than any other compost bin?

We do not know the answer – only detailed testing will unravel this.

However what we do know is this…

Composts differ in physical structure and chemical composition. HOTBIN compost often appears much wetter and sticker than other composts. We believe some compost will be better for soil fertility than others. We believe those with higher humus content will prove to be the best. We have some evidence it might be better based on the physical properties and that these properties are potentially linked to higher humeric substance content.

Why not join the debate and help us sort this out.

We need to define and analyse what makes fabulous compost. This has to be tested by soil science labs, it has to follow all the norms of science (evidence, repeatable methods).

If we have a standard for the very best compost, it is pretty easy – You never know we could even have an annual competition and give a prize for the best compost and best composting method!



1 Comment

Filed under Compost, In the news

Can you compost cigarette butts?

A number of composting advice sites indicate cigarette filters are made from synthetic plastics and do not decompose! We disagree – controlled hot Composting of cigarette butts is viable. Please read on to find out why! 
Whether a material IS or IS NOT compostable (i.e. biodegradable) is a matter of scientific fact. We like to check the science and leave you better informed.  It is rare for us to re-mind our readers our FAQ advice is provided on ‘without guarantee or indemnity’ – but on this occasion, as the topic is going to get people ‘hot under the collar’, a reminder that this is our reading of the science – we are only seeking to help inform your decision.
Searching the literature, we found that cigarette butts (the white filter bit) is made of ‘synthetic cellulose acetate’. That may sound non biodegradable but this is not the case. You can evidence this very quickly – a staggering 4.5 trillion butts are discarded each year (We can’t find a source for this number, but it is used widely on many sites, so let’s assume it is accurate). If these butts are not biodegradable – where are they now? Mass consumption Smoking has been around for 100 years or so. Despite the efforts of our Councils, if they did not decay, our sewers would be blocked and our streets piled high with cigarette butts.  Now for the science proof!
The filters are mainly made from a synthetic polymer called cellulose acetate. All sounds a bit scary, but not really. Acetic Acid (vinegar) is one of nature’s building blocks – life on earth needs it. Cellulose acetate is just lots of vinegar molecules joined together into a chain. Cellulose acetate is a short step away from cellulose (i.e. wood!). Most cigarette butts apparently still use natural cellulose acetate (i.e. tow from the wood pulp ). Even if they do not, synthetic (i.e. man made) cellulose acetate is man’s copy of nature’s science. It is used all around you – wrapped a present with cellotape recently, kept any photographic film (pre digital!) – that’s all cellulose acetate.
How fast cellulose acetate decays is directly related to the composting conditions – and principally the temperature of the heap (Q10 equation). You will often see quotes of 3,10 or 50 years as estimates for cigarette butt decomposition time. This is directly comparable the time it takes to decompose lignin (i.e. wood). Most of these tests are done outdoors (so an average of 10C is the temp for most tests). If you increase the decomposition temperature to 60C, you can divide this number by 32 and you’ll get the time it takes to hot compost it. So 10 years at 10C = 4 months at 60C (Again this is directly comparable to wood in an outdoor heap and wood in an IVC composting plant.
Even if we agree it is biodegradable, surely we do not want cigarette butts in our compost bins – they are full of toxic, carcinogenic tar chemicals the list of additives runs into 600 approved of by FDA for addition to cigarettes. If you really want to see some serious chemical names have a look at Wiki – Yes there are carcinogens in butt filters, but don’t forget – burning wood, fire smoke, the original tobacco plant, and much of nature – also has these nasty chemicals.   Someone may have tested every single item and may challenge back, but looking through the list, from our knowledge of composting bacteria, they all look like readily biodegradable organic chemicals (i.e. bacteria food). These chemicals are built up in plants and broken down by bacteria all the time. (Take the logic to the extreme – if the carcinogenic chemicals made in plants were not biodegraded,  then over the millennia they have been made by plants, they would have built up in soils – maybe even to a level that would have made soil toxic to humans?
What about the risk from “TMV – tobacco mosaic virus”. From our reading on the subject, claims are made that small fragments of tobacco carry the virus over from the tobacco leaf into the cigarette and onto the filter.  TMV is known to be resistant to low temperature composting.  However read wiki: If your heap is hot (60C), the virus is going to outcompeted, die and be eaten by the thermophilic bacteria. If you add in the fact that remote chance TMV survives the burning process at 200C, a small chance a tiny fragment gets into filter and that a tiny fragment is not then eaten by bacteria – TMV from composting butts looks a really low risk.
Only you, as the composter, can make the decision whether to compost your cigarette butts. I do not smoke, but if I did, I’d be more worried about smoking than composting cigarette butts!
So finally – what’s the alternative? Leave them lying around, hope someone cleans them up and takes them to landfill! Then what? Well they will just decompose anaerobically and release methane!
Proper HOT Composting of cigarette butts looks sound!

Leave a comment

Filed under Hot Composting, In the news, Uncategorized

There is more than ONE alternative to sending food waste to Landfill

Ban food waste from Landfill?
Collect and reprocess it via anaerobic digestion (AD) instead? Well yes and no!!

Respect the 3Rs: we should reduce food waste. Accepting there is always going to be some waste to treat…

There have been renewed calls to ban food waste from landfill in the Guardian today .  The report’s co-author Quentin Maxwell-Jackson is reported by the Guardian to state: “Anaerobic digestion technology has so many clear advantages over other waste treatment and energy generation options that it is very surprising it has not taken off in a big way yet in the UK.”

Calls to ban food waste have been made before. The Government’s stated policy is collection and reprocessing food waste via AD.

It is still probably still too early for the policy makers to ban food waste from landfill as the UK does not have the capacity ‘coming on stream’ to reprocess it via alternative means.

Every new AD plant takes time to get planning permission, to build and commission. At out last reckoning, about 3 major were due to come on stream next year and we estimated the UK needed 300 to divert food waste from landfill – it is going to be a huge cost and long path.

AD makes a lot of sense – we need a collection/reprocessing technology that caters for the majority and we know only about 15-20% of the UK population does (or will) home compost and traditional home composting has never been appropriate for all food waste.

We should not let the historic issues of home composting all food waste (including cooked food, meat, fish, bread, cakes, rice, pasta etc) that create a stinky odour that deters people and attracts rats, flies from continually reviewing technology for home composting. The HOTBIN team has real factual evidence that the HOTBIN has changed home composting of food waste for the better. Users have changed behaviour and are diverting all food waste from landfill. We estimate 5m current home composting households could divert all food waste and make a contribution – immediately.

100,000 HOTBIN users would equate to 1 new big AD plant.  Delivering a million units a year (we wish!) is a logistics co-ordination issue – the capacity can be made available very quickly.  We understand home composting is not for everyone – but we need to make a dent in landfill now and it can be done now.

There are other reasons why AD is not the ‘be all and end’ of reprocessing food waste. Reprocessing is a complex combination of user behaviour, logistics and technical facts. Yes AD has advantages, but so does home composting. Home composting removes the need for collection and transport, the compost can be used in the garden (reducing fertiliser and peat consumption) and adding organic matter and humus back to into soil is essential to soil fertility.

Help us win government support – HOTBIN composting diverts domestic food waste.
[At present we are pushing water up a hill and knocking on closed doors.]

Leave a comment

Filed under Compost, Hot Composting, In the news, Recycling Food Waste