Permaculture Review the HOTBIN Compost Bin – They Love it So Much….
John Adams and Maddy Harland at the Permaculture Magazine review the HOTBIN compost bin. They loved it so much, they decided to add it to their green shopping supplement.
Over the years I have tried most ways of making compost but I have never found one that really suited my requirements until Maddy showed me her Hotbin. I was really impressed that it worked even in winter, how quickly it made compost (about 90 days) and that it could even cope with cooked food scraps. I just had to have one.
The Hotbin certainly gets hot. Last summer it was positively thrumming (up to 60ºC). There is never any smell from the bin and the process is fast. There were also no flies as their eggs cannot survive the heat in the bin.
We both love this product so much we have added it to our Green Shopping catalogue.
Download and read the full review here.
Buy your HOTBIN compost bin online today.
Tumbler versus HOTBIN
Tumbler compost bin versus HOTBIN with no turning
If you have landed on this page, you are probably trying to decide whether to buy a tumbler compost bin or the HOTBIN. We offer you a quick ‘expert’ recommendation and a more detailed list of items so you can evaluate the type of compost bin for yourself. Alternatively jump to over and read what HOTBIN customers say
Our expert recommendation: As soon as you set a goal to compost all food waste (including meat, leftovers, bread, pasta, etc), and you want to compost all year round (through winter), with no vermin, flies or odour, then you need to opt for a specialist ‘hot composting bin’. Many tumblers are not capable of hot composting. If you hot compost and use a bulking agent there is no need to turn your compost.
Decide for yourself (list of things you should review):
To establish if a product is “better” you need to take a step back and ask – ‘What am I trying to achieve?’
There are two sets of features to look at. The first group looks at whether you want to hot or cold compost, and the second group look at how easy the compost bin is to use.
Group 1 – Hot or cold composting?
Do you want to:
- Compost ALL food waste from a typical domestic home
- Compost all year round (i.e. through winter)
- Compost faster typically less than three months
- Compost difficult garden wastes (e.g. weed seeds, couch grass, etc.)
- Compost without rats, flies or odour
- Compost without turning (fork over the heap)
Vendors will try and persuade you their bin will do ‘a lot’ and you can ‘control things’. To a degree this is true – but there is a huge performance gap between a bin designed to hot compost and a tumbler that holds waste while it cold composts.
- Feed it the right mix of chopped up waste
- Retain heat – ie insulate it by using specialist insulating materials
- Aerate – harness the science of buoyant airflow to get air to each bacterium at microscopic level
- Control water – remove excess water from the mix
- Enclose the waste, remove odours and control vermin and flies
The items are connected – get all five right and it is a virtuous circle, get one wrong and it can quickly form a vicious circle, spiralling downwards out of control.
Feed it: Some materials compost faster than others. Feeding chopped up, ‘easy to digest’ waste allows fast digest and hence fast heat release.
Retain heat through Insulation:
All things compost faster as a function of temperature (read about the Q10 equation here)
. No compost heap will compost faster unless
it retains heat. Plastics are very poor heat insulators – do not get fooled by names like ‘thermo’ and a few extra mm of plastic. You need a top quality, waterproof insulated material/ Just like your loft insulation ask for U or R value rating! Most tumblers have no insulation of any significance so they do not retain heat. The HOTBIN is designed to control both conductive heat loss (via insulated walls) and convective heat loss (hot air flow). If your goal is to hot compost; walk away from non-insulated bins. If you goal is to compost typical amounts (2-5Kgs) of food waste through winter, check the insulation works – look for user endorsements offering time & temperature graphs using on known amounts of waste (Kgs/week). We are NOT aware of any insulated tumbler guaranteeing winter hot composting of 2-5Kgs per week.
Aerate the waste:
You can hot compost without turning! The science (ref in T Huag, Compost Engineering) states air introduced via turning will last only a short time. If you have twiggy/woody material that maintains ‘free air space’ structure and a temperature gradient, it will aerate via buoyancy air flow. To learn more about the theory of “no turning” visit our buoyancy airflow and free air space faq
Plus you need to take into account spinning or turning a compost tumbler is not always easy.
100 litres = 50 Kgs, 200 = 100 Kgs.
Even with levers this can be hard and it places huge stresses on plastic and metal joints.
Control moisture: This is critical to the composting process. Kitchen scraps are wet, as is grass clippings need to be balanced with dry materials. Some tumbler models have drain holes in the drum, and also a collection chamber in the base to receive the “compost tea”.
Wet waste: Wet waste tends to rise and then slumps to bottom – it churns into a solid sludge- the last thing you need! Wet waste is the norm when composting all food waste. This is really easy to handle in the HOTBIN – you just add shredded paper and bulking agent to balance the system.
N.B. Leachate: most of the excess water is driven off as steam in hot composting. Some excess will drain down. Look for a bin/tumbler that has some form of leachate collection
Control Odour: All composting produces odour. Aerobic composting avoids anaerobe pungent putrid odour – but it has a cabbage odour. You need to filter odour and reduce the any possible chance of attracting flies and vermin. Check if your tumbler has any odour filter mechanism – the HOTBIN does!
Pest control: Do not get sucked in by statements like “compost tumblers are 100% pest proof since they are fully sealed”. We believe no domestic compost bin is rat proof. Rat experts will tell you they will eat through all plastics (be it 3, 15mm PE or 50 mm EPP as in the HOTBIN) if there is any gap. Understand vermin – what attracts them (odour, warm and quite nesting sites), then look for design that makes the bin highly rat resistant. If you bins has ANY open holes of 0.5cm or larger and odour you will have problems sooner or later. Always look for off the ground, and look for a filter that removes residual odour to a very low non-nuisance level.
Group 2 – Usability factors
What are the key items that make it easy to use;
- Loading and unloading
Assembly: Bit of a preference – we suggest you look for bins that come ready assembled or at least require very little self assembly. HOTBIN requires none.
Loading and unloading: Small loading and unloading hatches panels are fiddle and difficult to use – it is a big issue for some composter. Some tumblers are good – others are hopeless. The HOTBIN is OK.
Batch or continuous: You can fill the HOTBIN to the top and leave a batch to mature (batch) or more commonly, you keep filling at the top and take out the compost from the bottom without stopping (continuous). With most tumblers there is the issue of when to stop adding new materials so that the whole composter can “finish” and the compost can be removed. Dual chambers are better than single so you can swap compartments, otherwise you may be looking at two bins. (This is a bigger issue if your goal is compost food waste over winter as you cannot stop for 2 months.
Durability: Choose carefully! Tumblers tend to be more heavily constructed since they need to be strong enough to hold the full weight of the composting materials. This does not always work – many fail at the joints and stands. Inspect the supporting legs and the central axis connection – they should be built to last years of use (Check for customer’s reviews after years of use!). The HOTBIN has no moving parts – and only a door to take on and off.
Size & Capacity: Avoid thinking bigger is better. Hot composting is typically 10-30 times faster – so you need vastly less capacity. When hot composting, match the size to the amount of waste – it is harder to get a big tumbler hot with a small amount of waste – the laws of physics do not support small amounts of waste getting or staying hot in large empty bins!
Price or rather value for money:
- The HOTBIN = £120-150
- Non-insulated tumblers = £70-500
- Insulated tumblers = £170-£450
HOTBIN composting supply a compost bin. If you are wondering how and why we are open about offering the secrets of buying the right bin – well its straight forward – our product is excellent, the customer’s reviews say it is excellent, we have used robust composting science and engineering for the design and operation. We have confidence you will choose the right product.
Jump back to HOTBIN products page. Jump back to your shopping cart
Grass composting in the HOTBIN
How to compost grass in the HOTBIN composter. What can you expect when you add grass into the HOTBIN
As we explained in our previous grass post there are advantages to adding cardboard (or shredded paper) plus bulking agent (wood chip) to the HOTBIN to help you compost grass most successfully; it helps calm the ammonia smell and creates extra structure.
Here’s what happens to grass in your HOTBIN through a series of pictures.
Grass added to the HOTBIN
One hour later …
24 hours later…see how it has shrunk already!
48 hours later…
4 days later…this picture speaks for itself
7 days later…It’s almost gone and is steaming away!
Our control experiment!
We put some grass in a bag outside with no insulation… the temperature never gets above 30C
After 24 hours…
After 48 hours…We added some insulation on the top to see if this helps?
After 4 days…The insulation hasn’t made a difference!
After 7 days…there is still no real drop in volume
How to compost grass lawn mowing
To get fast superb results when composting grass lawn mowings in the HOTBIN:
Add 40 parts grass with 20 parts shredded paper and 1 part wood chip (bulking agent)
Typically this is a medium sized lawn mower collection box (40 litres) with a full carrier bag of shredded paper (20 litres) and 4 hands full (one 2-litre measuring jug) of bulking agent.
If you want to view a photographic sequence of grass compost stages, you can jump to our post on steps / stages of grass composting.
Below we explain why this recipe works, why just adding large amounts of grass can be problematic and offer 6 different options for handling large volumes of grass cuttings
The problem often seen when composting grass is you end up with a black slimy layer that stops the compost heap working.
In a HOTBIN you should get brown mulch in 7 days
Grass is one of the quickest materials to compost. In the HOTBIN you can typically convert grass to mulch within 7 days. Grass is so quick to heat up to 60-70C, the HOTBIN team recommend it to help accelerate and increase temperature quickly.
BUT! You can end up with a black anaerobic slime
In traditional compost heaps, it is one of the most troublesome materials to compost. Grass often heats up for 2 days and produces a very distinctive whiff (ammonia/urine). After 2-days it then ‘collapses’ into a cold, wet, slimy black mass that smells horrible (anaerobic mush).
Funnily enough we don’t have a picture of this as if you do it correctly in a HOTBIN it shouldn’t happen!
Composting grass successfully requires a little bit of extra composting knowledge but the real secret is matching the amount of grass you generate with the time and effort you have available.
Why does grass turn into a slimy putrid mess?
The ‘black slime’ is due to anaerobic conditions, i.e. excess water and too little airflow. Grass (lawn mowing) has a high water content (>80%) and no lignin (i.e. no woody stalk). As grass starts to decompose, the plants cells break down and become soft; water is released. The grass collapses and forms a thick impervious layer and airflow decreases. This in turn means the water is trapped, the process slows and a vicious circle is created where water is not removed, all oxygen stops flowing and aerobic bacteria cease to release heat. The heap cools and anaerobic bacteria take over releasing obnoxious odour and resulting in a ‘black slime’.
The golden rules for successfully composting grass are:
- Remove excess water
- Keep the grass aerated
- Balance the mix to avoid ammonia odour
So how do we get rid of excess water, keep the waste aerated and avoid both ammonia and or anaerobic odour?
- To remove excess water
You need lots of heat, i.e. you need to be ‘HOT composting’
- To keep the grass aerated (i.e. get air/oxygen into the grass layer)
You need buoyant airflow which requires a temperature gradient and a structure with spaces and gaps so the air can flow up.
Unless you have the means to force airflow (e.g. a pump / blower), or you can constantly turn/tumble (yes we mean constantly), then you are reliant on “buoyant airflow via the chimney principle” – and this requires the grass to maintain a structure with small air spaces (ie not a thick wet slimy mass!).
To get a structure that stops grass collapsing into a slimy heap, you need to add what we refer to as a bulking agent (typically this is wood chip). The bits of wood chip act like ‘stacking blocks’ and the air flows around them. Simple but essential!
- To avoid ammonia odour
To prevent excess ammonia, you need to be adding a fast/easy to digest carbon material like shredded office paper or chopped up corrugated cardboard.
The odour is caused because grass has an excess of nitrogen which the bacteria are unable to use as fast as it is released. So it forms ammonia gas and evaporates away. You are most likely to notice this when composting and/or turning large quantities of 1-2 day old grass lawn mowing. After 3 days things slow down and the nitrogen is no longer in excess. Turning grass heaps does not prevent the odour – it enables the trapped gas to escape ‘all in one go’. (If you have done this job, you may well come back inside the house and realise your clothes smell of ammonia!).
The HOTBIN does have an odour filter in the lid that does remove ammonia odour. But, when you add a whole box of grass in one go without anything else, the filter gets temporarily overload for 2-3 days. To prevent the odour during the initial 2-3 days you need to balance the carbon/nitrogen ratio.
You achieve this by adding a dry high carbon waste. The key here is to add ‘easy to digest carbon’ such as corrugated cardboard or paper shredding. Woody items like sawdust, shavings, wood chips are high carbon – but they are not easy to digest, so will not balance the C/N during the critical 2-days of intense activity. Here is the challenge – you need a lot of dry carbon! A 40L grass box (a typical mower box), needs 20L of paper – that’s a whole carrier bag full. It also needs to be mixed with the grass. Not everyone wants to do this, especially after cutting the grass. Below we outline a few options about different methods you might want to follow.
Large amounts of grass waste need extra steps to compost quickly, without ammonia and without turning putrid. Is the extra effort worth it? We think so! Each year fertilising grass lawns consumes considerable inorganic fertiliser – adding the nutrients back via compost is environmentally better.
Below are six options/choices for composting grass. Often you can ‘mix ‘n’ match’ routines at different seasons and times of the year to cater for the varying grass volumes.
1) Small to medium lawns – add grass into your HOTBIN each week
The HOTBINn will easily compost grass from a small-medium lawn (approx 40 litres/week or 1 large grass box per week, filling about a quarter of the bin each time).
This will generate some odour that you may well notice for 2 days. If this bothers you, there are a couple of methods to solve this:
- add shredded paper or corrugated cardboard in ratio 2 parts grass to 1 part paper
- Only add half a box, then return 3 days later add the other half
|Grass volume / Weight
||To Avoid wet slime
||To Avoid Ammonia
|40 litre (approx 20 Kg)
||Add 2 litre (a measuring jug) of bulking agent. Mix in well
||Add 20 litre (a full carrier bag) of shredded office paper or chopped up corrugated cardboard).
Results in approx 1.6 Kgs of compost in 30-90 days
2) Large lawn – use a dedicated HOTBIN for grass
If you have a large lawn and generate 3, 4 or more boxes each week, then you will need to consider a dedicated HOTBIN. It will cope with 2-4 boxes (about 60-80L) per week.
The same rules apply – but adding and mixing in large amounts of paper is intensive and requires a high degree of commitment – perhaps not what you want straight after cutting the lawn! Large lawns allow the HOTBIN to be located away from your seating area – so we suggest you save your effort of adding shredded paper to eliminate ammonia odour – just leave the HOTBIN down the garden and reap the benefit of fast compost without anaerobic slime.
|Grass volume / Weight
||To Avoid wet slime
||To Avoid Ammonia
|80 litre (approx 40 Kg)
||Add 4 litre (a measuring jug) of bulking agent
||Leave remotely and accept ammonia for 1-2 daysAdd 40 litre (a full carrier bag) of shredded office paper or chopped up corrugated cardboard).
Results in approx 1.6 Kgs of compost in 30-90 days
3) Leave the cuttings to compost on the lawn
Many gardening sites now actively promote leaving grass cuttings on the lawn. Normally you use an adapted/special mower blade that chops the grass into very small pieces (2-5 mm) and thoroughly spreads them. The method is to weekly trim of top third of grass and spread this evenly so it composts quickly, adding nutrients back to soil, but not creating thatch. If you have the grass ‘trail line’ down side of mower, then this will rot into mulch that blocks light and growth and does create thatch. Please refer to manufacturer for correct mower blades/settings. If you walk regularly on your lawn – you may find bits get on your shoes and are walked back into the house!
4) Best of both worlds’
Add the first few cuts of the year which tend to be large (say 3-4 boxes) into your empty HOTBIN. The bin is full for a week or so, and then rapidly becomes half-empty allowing ongoing use with food. After the spring cut, leave grass cuttings on lawn. Occasionally (e.g. when cutting hedges) add the grass box back on the mower and collect grass to complement garden ‘browns’.
5) Transfer grass to Local Authority
This is unlikely to interest HOTBIN users, but it is possible to have grass collected at the kerbside and taken to the council recycling centre. We are strong believers in home composting and believe in the environmental benefits of saving fuel and transport.
6) Allocate a large, remote area of garden to build smelly grass mounds
The mounds will tend to be smelly and go anaerobic, but it is fast to empty and dump lots of grass. We had rave reviews on how fast and efficient the HOTBIN is with grass – so maybe you do not need this option anymore!
So in essence it is easy to compost grass in your HOTBIN but depending on the amount you need to consider which methodology is best for you.
Worms and HOTBIN composting
A question we often get asked is; do I need to keep my Wormery now I have a HOTBIN?
The simple answer is no and the key benefit is that the HOTBIN can compost both food waste and garden waste. Therefore you can save space, reduce costs and still keep your food waste out of landfill.
So what is worm composting?
Worm composting is using worms to recycle food scraps and other organic material into a valuable soil amendment called vermicompost, or worm compost. Worms eat food scraps, which become compost as they pass through the worm’s body.
So what is HOTBIN composting?
The HotBin is a simple design that helps maximise what nature does by bringing together the right conditions to make hot composting easier. It does this by providing effective aeration between the bottom air inlet plate and the air outlet rotating valve, removing excess water through the valve as steam and allowing you to control the rate of heat loss. You can compost 100% of all domestic food waste in the HOTBIN without inherent problems with odour, vermin and flies. This includes left over meals, plate scrapings, meat, fish, small bones, bread, cakes, pasta and rice. Your food and garden waste will be turned into rich organic matter for the garden every 90 days.
Worms in the HOTBIN?
You do not need to add worms into the HotBin however you can – either directly by adding into the base layer (which is cooler) or inadvertently by adding worm eggs and worms into the bin via small bits of soil and old compost . Most of the worms and worm eggs will be killed by high temperatures (>45C) but a some will find there way down into the base layer and continue to work on the base layer compsot.
However, worms can be beneficial to composting and can be added if you want to. But a word of warning do not add them into the upper active layer (60°C will kill them) only add worms via the hatch panel where the compost will be cooler. Worms will help to decompose waste and leave mucus in the compost which is proving beneficial to soil fertility.
As the HOTBIN is no ordinary composting bin as you can use it to recycle than just vegetable kitchen waste in it. The hot temperatures achieved during hot composting make composting all food waste in the HOTBIN a safe home composting system that recycles a whole lot more than just potato peelings.
So if you were thinking about a Wormery as a form of recycling food waste why not consider a HOTBIN as it composts both your food and garden waste together.
The Ultimate Guide To Compost Sieving and Sieves
Many people will use compost ‘as it comes’ from the compost bin and just dig it into the soil around plants or into the vegetable patch.
Sometimes it is preferable to have fine sieved compost for use in potting up seedlings or to use as a lawn top-dressing (it does wonders to reduce moss!). Large pieces of compost are hard to rake in and can cover the grass and act as ‘mulch’ – not the desired result.
Mature HOTBIN compost at 3 months
I have tested a few compost sieves and I thought it was time to summarise how they perform and offer a view on the how worthwhile sieving compost is.
Sieving compost can be tricky and labour intensive – it does not take too many lumps of wet moist compost to clog up the sieves.
HotBin Compost – Good and ready after 3 months
The Plastic Hand Sieve
A Plastic hand sieve will cost £4-10. These work OK if you just have a bucket of compost and the compost is not wet. When you only have small amounts of compost, the price/performance is hard to beat. However, once you start to get into bags or wheel barrow loads; the hand sieve is too time consuming. You tend to end up with aching arms and a stiff back! The plastic pan sieves struggle with moist compost – it will just roll into balls that won’t sieve. (There are a whole range of metal hand sieves that work the same as the plastic ones but cost a lot more).
A 33cm plastic garden sieve
The Rotary Sieve
The Rotary sieves cost between £30-40. They are OK with dry compost and compost that is already quite ‘fine’. However they tend to clog when used with moist compost. Some large pieces can jam in the rotary arm and you’ll need to stop and clear them out before carrying on. (NB this review was based on third-party input not our own test).
The CRS400 Rotary Soil Sieve
The Watford Sifter
The Watford Sifter costs approx £120-150. In my tests it worked better with soil than compost. It struggled with wet compost – it tended to clog and stick in centre of sieve and it did not tip ‘up and down’ far enough to move it from this position. Good for medium or large loads and certainly a good option if you have both soil and compost to sieve. With only small amounts compost, you might struggle to justify the cost.
The Watford sieving HOTBIN compost which is 3 months old and typically wet & sticky
Likes / dislikes:
- You get two screens – fine and coarse.
- Easy to push ‘up and down’
- A bit of a ‘pain’ to get the retained coarse material out of the sieve tray. In the end, I was continually lifting the whole box and tipping it out. It’s a heavy lift when not much is sieved. This issue goes away if most of the soil/compost gets sieved through – but if it is all fine in the first place there is no need to sieve!
The Scheppach Sieve
The Scheppach costs in the region of £350-400, this is a serious piece of kit. It is a trommel design (rotating cylinder) and uses and an electric motor to turn it so it also needs an electrical supply! It will handle significant volumes of soil and compost. We have not used this kit, but we know three large-scale gardeners/composters who do and they all rate it highly. If you are only using it 1-3 times a year, our opinion is it is questionable how much value you will actually get. Probably one for the professional and/or allotment/community schemes where you can share it. PS: It also takes a lot storage space.
The Scheppach RS400 rotart sifter
The Compost Sifter
Compost Sifter costs £155 (excl £40 delivery to UK). It comes from Belgium. It uses a similar rotary tunnel (trommel) design as the Scheppach – but it is turned manually via a handle. By long way, it required the least effort and sieved faster. The mesh (hole size) is smaller than the others (8mm). In our tests it struggled with wet compost, however, after initial disappoint with wet compost, it absolutely whizzed through dry compost.
(PS the photo below was taken before wheels had bee added)
The Compost Sifter – Assembled with just wheels to go
Likes / dislikes:
- Ease of turning – real winning feature
- Retains oversize and easy to get it out via panel that detaches
- It is very heavy – fine once set up on wheels, but you may need 2-people to get it out of box and set up on the frame.
- It still struggles with wet sticky compost – but so do all compost sieves!
(Oct 2013: the sifter team have introduced an ingenious compact version that fits on a wheel barrow:http://www.compostzeef.be/home.html )
For more information please visit the website above
The cheapest and most cost effective method
Please jump to this post to see the results of the most cost effective and low cost method
Sieving compost can be tricky and labour intensive, especially if it is wet and sticky as it tends ball into large lumps and clog sieves.
After numerous tests on HOTBIN compost, we think we are on solid ground to say if you want to sieve the naturally sticky wet HOTBIN compost you will have to dry it first (see how below). All the sieves will perform significantly better with dried compost.
Our next question is: Is it worth sieving compost?
This is not just about the cost of the sieve and the time and effort that goes into sieving. The most beneficial part of compost is the group of humeric substances. These compounds impact soil fertility as they enhance root uptake of minerals and water. It therefore follows the biggest benefit comes from digging humeric substances into the root zone. If digging in, one has to question if the effort to sieve out any big bits. Large over sized lumps will compost down in soil over 12-24 months. As long as the total volume of large pieces is low, the ongoing composting of these pieces is unlikely to affect nitrogen availability during the final composting period. With HOTBIN compost there is always about 10-15% of small 0.5-1.5cm wood chip (bulking agent) pieces that remain in the compost. Our tests show these pieces are covered in layers of humeric compounds. We believe these pieces of wood chip are slowly composted as they are coated and protected from rapid decay. Whilst in the soil, small pieces of wood chip also aid aeration and soil tiling.
There are applications where sieved compost is useful e.g. when used as a lawn top-dressing (i.e. raking in a thin layer of compost on to the grass), or when creating a potting mix for seedlings. Lawn care is a huge part of British gardening. I personally have seen good results from top-dressing moss ridden lawns (high clay, poor drainage) with sieved compost. For those of you that want to drop dress, the method is outlined below.
In summary, for most compost users and most types of compost application, we do not believe drying compost and then sieving is worthwhile.
Compost and lawn top dressing
- In late Autumn take out your HOTBIN compost and dry it (we spread it out as a thin layer on patio / large sheet polyethylene)
- Add dried compost to compost sifter or like to sieve
- Sieve and bag up
- Spread on grass and rake out to about 1cm layer.
This will take huge quantities of compost – but the rewards is you will not be spending much on lawn fertiliser or moss killer!
Can I add Autumn LEAVES to compost in my HOTBIN
Leaves can go in the HOTBIN and they make great humus.
If you have a lot of leaves (>10 litres, a bucket load), you need to tweak the recipe to ensure they HOT compost.
If you only add thick layers of leaves into the HOTBIN, it is unlikely they will rise above 20-30C as the woody nature means they are hard for bacteria to digest and hence heat is released slowly.
To HOT compost autumn leaves, see the recipe below:
How to HOT Compost Autumn Leaves
There are two parts to successful composting of autumn leaves.
1) Adding a nitrogen source to balance the high carbon in leaves
2) Ensuring that there is enough ‘easy to digest’ waste (e.g. greens, food waste, shredded office paper’ (which creates heat quickly) to keep things hot whilst the hard to digest woody material (in which heat is released slowly) are also digested. In some cases solving (1) & usually solves (2).
Here’s what you need to do to ensure you get the best out of your HOTBIN
Step 1: Shred leaves
Leaves tend to form a dense matted layer that restricts air and oxygen flow within the HOTBIN. We advise shredding the leaves (e.g. using mower or a hedge trimmer).
Step 2: Mix leaves with easier to digest materials like food waste
Many people simply will not have enough food waste to mix with high volume autumn leaf fall. You can cheat a little by adding another easy to digest waste to go with the leaves such as chicken poo, chicken pellets, or a sprinkling of blood bone meal.
The ideal waste to mix with autumn leaves is grass lawn mowing – unfortunately, it is rare in UK to be able to get the mower out in Autumn as it is too wet and compacts the lawn soil. If you have room storing leaves in a wire frame box ready for spring and first grass cut can work really well . (Avoid sealing in black bags – the leaves will go anaerobic (see below for anaerobic method).
Step 3 – Do not add too many each time – little and often is best
More than 10cm (20 litres) of cold wet leaves in one go will “stall” the HOTBIN. The cold leaves will lower the temperature of the HOTBIN below 20°C and the heat production falls below that needed to re-heat. So store the leaves in a pop up bag, protected from rain and add over a couple of weeks – you’ll be amazed how fast they compost.
If you have a large garden with lots of trees and mounds of leaves then possibly doing a little bit each week in the HOTBIN is impractical. Try the following – shred the leaves (e.g. using lawn mower), store in a wire frame or cold compost heap until spring. Mix with first grass cuttings in large volume piles. Turn occasionally.
Leaf Mould Versus Composting
If you are collecting leaves into a wire frame then you might go down the route of just leaving them in the box and waiting 1-2 years for leaf mould.
Leaf mould versus ‘bagging’ i.e. anaerobic digestion
Many compost sites note that ‘bagging’ leaves in black plastic and tying off will create a black slime that can be used as compost. What this really means is you are anaerobically digesting the leaves down to compost. To an extent this is ok, our point would be AD creates methane and you are releasing a GHG that is 24 times more harmful than CO2. And we hope you would agree that every little bit avoided helps.
Aerobic composing is carbon neutral. Also to be honest – the black bags absolutely stink when you open then!
You can now successfully compost large amounts of Autumn leaves in your HOTBIN.
This AUTUMN could be the time to RETHINK composting?
Autumn is coming – It’s will soon be time to start that big garden clear up again! Should you start to RETHINK your composting method now too?
You may well have wheel barrow loads of plant and weed being removed over the next few weeks.
What are you going to do with all your autumn garden waste?
1) Pile it all up as normal in that big heap – come back in spring hopeful of compost but most likely disappointed that you face the prospect of waiting another 12 months for your compost?
2) Take a different approach – join the HOTBIN composters and be sure of a fabulous batch of compost ready to dig in with you spring planting preparation?
3) Leave it out for the council green waste team to sort out – Oh dear! All that fuel, cost and effort to centrally reprocess it. Taking all that goodness from your soil this year, which means next year it has to be replaced by buying even more fertiliser, that takes even more energy and resources to make?
Composting during the cold autumn, winter and early spring months can usually be a very slow process. Especially when the temperature falls below 5C, the rate the bacteria work is almost nonexistent. The secret to fast composting is heat – and lots of it. Compost forms 64 times faster at 60C than it does at 10C. If you can keep your waste hot (between 40-60C), it will compost in 20 to 90 days!
There are many help sites that recommend building huge piles (minimum 1X1X1 m3), and then turning them regularly to keep them aerated and hot. But even this technique will struggle in winter as the heat produced by the bacteria is quickly lost to the cold air. (And it requires quite a bit of effort and space too)
This is why so many HOTBIN composters are happy – all the hard work to help support natural high temperature composting is provided by the HOTBIN. As long as you keep feeding it every week with enough waste – it will keep running at 60C. It has been tested and proven even with outdoor temperatures as low as -15C.
Not only can you get rid of all that garden waste, you will also be able to compost all your food waste over winter too.
Now if you were an early HOTBIN starter, your HOTBIN might be full already! If the bottom layer has been in there for 90 days, now is a good time to empty it to make room for your Autumn garden clear up.
It is always best to shred as much as you can (the smaller the pieces, the larger the surface area, the easier it is for the bacteria). Now if you don’t own a shredder then you can always use your lawn mower!.
Now you are ready to fill up HOTBIN to the top and get it back up to 60C .
If you have a large garden you may still have too much waste . So the best thing is to store it in pop up bag or on another heap. Remember to keep it covered to protect it from the rain. Where possible we suggest you store bags on stones/gravel so water drains out and some air can get in through the holes in the bottom.
You can add the excess waste every 4 days (about 20 litres 10 cms depth). As the ‘waste pile’ gets colder and older, reduce how much you add each week – But keep adding your food waste! (The bacteria need some easy to digest waste to keep the temperatures at HOT composting levels between 40-60C).
Keep going until all autumn waste is gone.
As soon as you start to collect a lot of autumn leaves – check out the ‘composting autumn leaves post’ as you need to tweak the recipe to hot compost leaves.
Remember the key to keeping it HOT is a BALANCE of ‘easy to digest waste’ made up of green stuff, food waste, plus shredded office paper’ (which creates heat quickly) with the hard to digest woody cuttings (heat released slowly), or partially composted waste (energy depleted).
Why not take up the challenge – find out what others have experience by visiting our ‘product reviews’ at www.hotbincomposting.com. Explore more about how it works by looking at our extensive ‘how to compost’ database, for example our ‘principles of hot composting’ article.
The HOTBIN is a simple design that helps maximise what nature does by bringing together the right conditions to make HOT composting easier. It does this by providing effective aeration between the bottom air inlet plate and the air outlet rotating valve, removing excess water through the valve as steam and allowing you to control the rate of heat loss.
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 http://www.bat.com/group/sites/UK__3MNFEN.nsf/vwPagesWebLive/4572237B0C2D456CC1257314004EF667
). 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 – http://en.wikipedia.org/Wiki/List_of_cigarette_additives
. 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: http://en.wikipedia.org/wiki/Tobacco_mosaic_virus
. 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!
HOTBIN investigates an interesting composting method
We had an interesting question come in last week!
Was Black Soldier Fly (BSF) composting the most efficient composting system ever?
After many years in composting, we had not come across BSF before, intrigue and a hint of competiveness that any system might be better than the HOTBIN, we did a bit of googling. You learn something new every day!
- BSF (Hermetia_illucens) is a species of fly with native to America (with a cousin down in Australia). There will be a UK entomologist who will no doubt identify a cousin in UK, but so far not aware – and hence possible reason we have not come across them in UK)
- It has a niche habitat – rotting food/manure. The fly lays eggs in compost and the larvae (some would say maggots) eat the food waste – and they appear pretty good at it. (This is no different to house flies and or vinegar/fruit flies – BSL are much bigger and eat more!)
- The larvae are not meant to be allowed to hatch into flies (ie pupate), they are collected and used as chicken feed and/or fishing bait
- There are a number of specialist bins designed to house, retain and harvest the larvae. As a food waste disposal system, it more closely resembles worm composting.
What about claims to be the “most efficient”? We are always suspicious of ‘fastest and best’ and try and uncover the scientific facts. There was no reference to a specific quote and we did not see the claim on sites listed below. It looks like there is enthusiasm for BSF, as highly efficient and this enthusiasm comes from the visible disappearance of food waste as BSF larvae eat food within 2-4 days. If you compare 4 days to “composting” even hot composting at 30 days – you might think it’s more efficient. But decomposition (eating waste food) is just a set of biochemical reactions involving enzymes – the rules are fixed: the rate at which reactions take place is governed by the Arrenhenius equation – which basically boils down to temperature. BSF Larvae die at 40C, thermophilic bacteria operate at 60C and in many cases 70C.
In simple terms, larvae at 40C work at the same speed as bacteria at 40. If we say composting at 10C is rate X1, then larvae and bacteria at 40C are X8 times faster, but bacteria at 60C are 32 times faster – speed wise, we think no contest!
But is speed what we need to focus on? What are we trying to accomplish? Are we seeking to dispose of food waste fast, make fish bait or make great humus with high nutrient and water holding capacity that dramatically improves soil fertility? (With the added plus of diverting food from landfill).
Nature eventually recycles all plant and animal matter back to carbon dioxide and water. Does it matter if the larvae eat food, then the chickens eat the larvae and then the bacteria eat the chicken poo? Or that the bacteria eat the food (and release carbon dioxide), but leave some residual waste (compost) that gets eaten much later and then finally becomes carbon dioxide. Both routes are carbon neutral and better that sending it to landfill where it will decompose anerobically releasing methane. BSFL larvae eat the food and produce a small amount of residual compost like material. Composting and hot composting produces a lot of compost for the garden. Compost is beneficial to the soil before it is finally returned to carbon dioxide.
We should perhaps note that for many humans, the reaction (rightly or wrongly) to flies, larvae & maggots are negative. Even though BSF appear as good guy (does not bite, sting or carry diseases problematic to humans), we know from experience (backed up by surveys), that one of the biggest reasons people stop composting is flies and maggots. The prospect of actively promoting lots of maggots in waste food seems at best destined as a specialist area.