Composting Human Hair and Orange Peelings in Sunny Spain!
We had an interesting enquiry today from a new user about to set up the HOTBIN in Spain on how to compost human hair and orange peelings.
“I have just ordered one [HotBin] for southern Spain. My hairdresser is happy to provide bags of hair. Is hair in large quantities ok? Also a juice bar has offered bags of orange peel. Again is this ok in large quantities? I want acidic compost. Thanks for your help. I am really quite excited about moving from cold to hot composting”
With the first snow of winter falling today, sunny Spain sounds great.
Here is a summary of the tips:
Hot Composting Human Hair
You can hot compost human hair. As with most things in composting, it tends to work better when mixed with other items. We do not have specific experience, but for a few months check it does not form into a dense thick layer that might affect airflow. Remember to give it a stir and mix in less if it does.
Hot Composting Orange Peelings From Juicing
Orange peelings and pulp from juicing will be a challenge for hot composting. They are very high in water content and an item often “too wet for hot composting”. You may need lots of shredded paper or to air dry the peelings in the sun for a few hours. (Also your dry hair might be a good balance – it really depends on how much of each you have). You will need to experiment but give a call any time if you need help to get the recipe right.
You mention ‘acidic compost’ – presumably you are trying to tackle an alkaline soil. I am not sure attempting to make acidic compost is the best route. Bacteria in the heap work best at neutral Ph. If the bin goes acidic (due to organic acids found in all plants, but high in orange peel), the compost will turn anaerobic, stink and slow down to a halt.
I think you will be better leaving the compost to work at neutral Ph and tackle your soil Ph either slowly by adding ‘neutral’ compost which will eventually bring the soil Ph down, or by adding a natural acidic mineral to the soil (eg sulphur or iron sulphate). You may know this, but just in case, take care because if you add too much you will cause issues. Best to get an exact Ph reading from the soil and then match this to the exact quantity (in grams) of the acidic mineral. The RHS has a good article on soil acidification: http://apps.rhs.org.uk/AdviceSearch/profile.aspx?PID=82
Sourcing “Trade Waste”- Do a Quick Check
I do not wish to put a damper on your ideas, but please check with your local traders and you will not get into trouble with the local Environment Agency or waste disposal officer. All waste from businesses within the EU is classified as ‘trade waste’ and rightly, each business is subject to rules to ensure the waste they generate is disposed off safely. As daft as this might appear, they might not legally be able to give you peelings or hair for home composting! Hopefully, your local agencies will be enlightened and see small quantities and home composting as a good route, but these things can get very sensitive depending on interpretation of the rules.
HOT TOPIC – TEA BAGS!
Can I compost tea bags? There is something about this composting question – it keeps coming back – it was on the Radio’s 2 Simon Mayo Drivetime today. Here is an answer that deserves reading our a cup of tea!
You may remember the HOTBIN composter featured on Simon’s Drivetime innovation slot back in February last year.
Toby Buckland (BBC gardening expert) gave Simon a quick summary of ‘hot’ and ‘cold’ composting.
We were interested to hear Toby Buckland noted that some tea bags do not degrade because they have plastic fibres in so you should go for the more ‘expensive’ paper ones with strings.
HOTBIN composting checked composting out tea bags sometime ago. After checking several manufactuirng sites, we found most of the fibre used is paper. Some manufacturers add a small amount of polypropylene fibre to make the bags stronger and allow them to create a heat seal after the bag has been filled. This appears to be a minuscule amount of PP fibre.
In cold composting the bags tend to present in the final compost. In the HOTBIN composter and hot composting they are degraded fast and usually completely within 3 months. Occasionally a bag will need to go through again – more so with the pyramid bags!
In summary – the tea leaf and paper is composted, the inert PP fibres remain but are invisible within the compost and do not affect the soil.
The Guardian did a feature on this three years ago – A report published a few days ago by Which? Gardening reveals that teabags produced by top tea manufacturers such as Tetley, PG Tips, Twinnings, Clipper and Typhoo are only between 70-80% biodegradable. As a result, gardeners are finding the net part of teabags – caused by the inclusion of heat-resistant polypropylene – left on their compost heaps.
Which? Gardening contacted the major tea manufacturers to check the content of their products. PG Tips responded: “‘Like most of the teabags in the UK, our teabags are made with about 80% paper fibre, which is fully compostable along with the tea leaves contained in the bag. The remaining packaging includes a small amount of plastic which is not fully biodegradable.”
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.
The Edible Garden Show
Hot Composting versus Cold Composting
What a brilliant turn out HOTBIN had in The Potting Shed at the Edible Garden show last weekend. There is definitely an appetite to learn more about the benefits of hot composting over cold composting and how it can contribute to reducing what each household sends to landfill.
If you didn’t get there you can read a PDF transcript of Tony’s presentation by clicking on the graphic below.
It essence he challenged the audience to consider during his talk whether Hot Composting was worthwhile or or just a lot of hot air!
He wanted them to reflect on these 5 key things:
- Time – is hot composting faster all year-round?
- Quantity – do you get any more compost if you hot compost?
- Endeavor – does hot composting take less effort?
- Quality – is the compost from hot composting any better?
- Planet – is hot composting good for the environment?
I think over the 3 presentation sessions that the only question mark remained was on whether it was more or less effort to hot compost! Well only you can decide whether the effort is worth it to achieve all the other benefits.
Our view is this…yes hot composting in a HOTBIN requires some active participation. This includes making sure you keep the bacteria happy with smaller pieces with a larger surface area and making sure you feed it approximately 1 caddy 2 times a week. But really the benefits of composting all food waste, more quickly, all year round to get a good quality compost whilst cutting your contribution to landfill is surely worth it!
You can read the full transcript of Tony’s talk below and let us know what you think.
Thank you to The Edible Garden Show for the opportunity to present and to Potty Innovations for the photography, we had a lovely time!
Remember you can also downlaod teh PDF form teh link above…
Hot Composting – Worth it or just a lot of hot air?
By Tony Callaghan, transcript of the Talk at the Edible Garden show 15-17th March 2013
Good morning, thank you for attending – when you volunteer for do talk, your worst nightmare is just 1 person in the audience, we have a full house and that is great!
My name is Tony Callaghan, I am the Inventor of a product called the HOTBIN. Today’s talk is about Hot Composting – is it worth it or just a lot of hot air.
I’d like to start at the end by asking, how are we going to judge if it is worth while? On the handout sheets you will see I have suggested 5 things we should ask and answer during this session:
- Time – is it faster, all year-round?
- Do we get any more compost?
- Does it take less effort?
- Is the compost any better?
- Is it good for the environment?
Keep these items in mind when we get to the summary!
I started my hot composting journey about 4 years ago. We had been in our new house 2 years, the black dalex cone had been filled with garden clippings and vegetable peeling from the kitchen, I had nailed together pallets to create a second bin and that was also full – it had carrot peelings over flowing from the top. One day the inevitable happened – the old rat popped its head out. I was politely informed to sort out the compost bin or stop composting!
Now all I really wanted was to find a compost bin online that worked and move on. I was looking for a 5-star review on Amazon etc that said this product works and customer really recommend it. I could not find it – I found instead was “it arrived on time / did not arrive on time, it was easy or hard to assemble – 1-5 stars, often with “I’ll let you know if it works in 12 months”. Of course no-one comes back to fill it the rating later. The more I looked the harder it became to find vendors that actually had case studies or evidence that the products worked. I got scared off and decided I would make my own. I had loads of attempts, kept reading website advice, adjusting, adding insulation, turning etc. They all work initially but then failed quite quickly. I soon released that something was amiss. Eventually out of frustration I bought a compost engineering book – 500 pages. Having read it cover to cover (I do have a science background!), I began to understand – some advice was out of context, other bits were just plain ‘myth’.
So let’s look at what hot composting is.
What is hot composting?
Could I ask for a show of hands – how many compost? (approx. 100/120 of audience); how many think they hot compost? (3-6 from 120); how many ever use a thermometer to check? (zero from 120)
In the UK, winter is around zero to 5C, spring 5-15C, summer 15-25C. The average over the year is 10C. Most UK compost heaps run at 10C. If you shower in the morning, that is normally around 35-40C. If you put your hand on a very hot radiator – that is about 60C. So when we say 40-60C is the hot composting range, it is very hot.
Why are we interested?
We will be looking at a number of benefits, but I want to focus on heat and speed first. I do not want to get too scientific, but there is a rule of nature called the Q10 equation. Very simply for every increase in temperature, the speed of reaction doubles. So if we take out UK compost heap as 10C, and say that is speed 1, then 20C = twice as fast, 30C 4 x times, 40C 8 x times, 50C 16 x times and 60C 32 x times faster. So a rough rule of thumb – if a material takes 12 months in a cold (10C) heap, it will take 12 days at 60C. Please do not go away thinking everything will compost in 12 days – it won’t – some things are faster than others.
How DOES it get hot?
People sometimes ask do we add heating rods and electric etc. The answer is no. The heat comes from the bacteria. As they work and reproduce they create heat. Think of it like going for a run – the faster you go, the more heat you make. There are two groups of bacteria we focus on the mesophilic who work up to 40C, and the thermophilic who work from 40-70C. Now the thing about the thermophilic bacteria is that other things do not survive above 40C. So flies get fried, worms make an exodus and come back in later as things cool down.
How do we make a hot compost heap?
We need to keep the bacteria happy. I’m going to look at 5 things. Think of them as linked circles – if they are all working, we get a virtuous circle and everything spirals up and we have success. If one of the links is broken, then we get a vicious circle that spirals down.
And we all know where it leads – the stinking pungent heap that upsets the neighbours, attracts more vermin and flies – and sorting it out is a very unpleasant task.
As I talk through the 5 items, I will try and compare it to other advice, and try to help you with the context.
Number 1 – Retain the heat
So we know heat increases the compost speed and we get compost faster. To hot compost, you also need to retain the heat.
We all know hot moves to cold. If we place a compost heap in the outdoors, the heat will rapidly move to the cooler air. It is a fact of life, a law of science. You cannot prevent heat moving out and the heap cooling – that is why most heaps in the UK run “cold”.
To retain heat we need to insulate and reduce the rate of heat loss. There are two ways of doing this: use compost to create an insulation layer – a very large heap (at least 1XX1m, preferably 2m3) – the outer one metre of waste acts as insulation around the central hot core. This is why when you read books about hot composting they almost always say you need a big heap with lots of material. (They might not know why – but the experience shows it works!). Alternatively we can use a modern insulation material like EPP (expanded polypropylene. 50mm of EPP has the same insulation as 1 m of compost. Think of it like insulting your loft, you can leave it losing heat, add 200mm of fibre glass wool, or add a super 50mm insulation board.
Number 2 – small bits please!
Every time you chop things up you double the surface area. Think of it like this – you can fit one million bacteria on a pin head (apologies during the presentation I think I might have said 500 million!). Now add a whole potato into the heap. The bacteria have to eat through the peel (designed to protect it) and then all the potato. If you chop it they can get to more potato faster. Give the bacteria a break and chop things up.
In the kitchen this really is not that hard. We tend to chop vegetables and even the broccoli stalk does not take much effort to run the knife through. But if you are lucky enough to have a large garden, creating wheel barrows of waste, it takes a bit more effort with secateurs. If you have a hedge trimmer you can use it to chop waste, a rotary mower is good for leaves, and if you do not have a shredder you might be able to share one with a neighbour. Chopping and shredding makes a big difference to all composting.
Number 4 Oxygen / aeration
All the audience has heard about greens and browns and Carbon/Nitrogen ration of 30:1. I do not want to focus on these…they are important but are not high priority. After all we can compost grass (10:1) and compost wood (200:1).
I want to focus on how easy things are to digest. So I would like you to think about your diet! If you had consumed a bottle of coke (other fizzy drinks are available!), then you would be running around for an hour or so on a sugar high. You can digest glucose very easily. Now if you had porridge oats for breakfast, the theory is the more complex carbohydrates are harder to digest and energy is released more slowly – so you have less of a high, but keep going to lunch time. Bacteria are very similar – there are things they can digest easily and things that are hard. Sugars and carbohydrates are easy, cellulose (the main parts of plants) are in the middle – relatively easy and things like wood that contain lignin are very hard for bacteria to digest.
If you want to get your heap hot – you need to add some easy to digest materials! Grass and food waste are both very easy for bacteria to digest.
How many people add newspaper to the compost bin (a fair few) And how many add shredded office paper (less). Has anyone added newspaper (especially balled up) only to find in 6 months it is a small blob of non composted mush? Newspaper is “bits of wood” (hard to digest), but office paper goes through another step and is de-lignified – it is cellulose and much easier for bacteria to digest – Try them both and see who much faster one is…
Number 4 Oxygen / aeration
You all know we need oxygen/air to have aerobic composting. If we have no air we end up with anaerobic conditions, and all the odour issues.
Where do we need the air/oxygen? Well remember our tiny little bacteria trying to eat the waste. They need air on a microscopic level – everywhere in the heap. Getting air to all the heap is a big task. Often you will read the books and they state drill holes in the side for aeration, or that turning is essential. Others will describe complex ducting and airflow tubes. We researched loads of different designs. It turns out the compost engineers really know their subject. Turning does not really help – unless you want to turn it every second of the day! Most turning takes the outer none composted waste in to create a new central hot core of waste. Aeration holes in side of bins do not work – air has a particular way of flowing – it follows the path of least resistance – so through the wall and up and out. Tubes and central aeration is even worse the hot air rises up the pipe and out. After much failed experimentation we started to do what the industrial composters do – we added bits of wood chip. Think of this like building blocks – the bits stack on top of each other, they do not collapse and the air flows up and over. So add cold air in at the base, draw it up, keep it flowing up to all parts using wood chip. Because the structure does not collapse into a slushy mess – you will find you no longer need to turn. We have found no aeration system that gets even close to the success of using “buoyant airflow’ with wood chip.
Number 5 – water – We know as composters that if the waste is dry nothing happen. The bacteria need water to develop. But excess water is also a problem. It blocks all the holes around the food and wood chip and no air can flow. Food waste has a lot of water. So if you see advice to wet your material until wringing like a sponge, that might be ok for a cold heap where the water can drain away, but it is a ‘no-no’ for hot composting. We normally have to add dry materials (like shredded paper) to balance to excess water in food waste.
So the 5 things to keep bacteria happy: 1) Retain heat (insulation); 2) Small bits (shred/chop); 3) Waste mix (some easy to digest); 4) Oxygen to all bits (wood chip – bulking agent); 5) Water (need, but not too much). Get all five right and we have the virtuous circle. If one is wrong then a vicious spiral down.
What about other things
Manage residual odour – all composting produces odour! We want to avoid the putrid horrible anaerobic odours. But aerobic still produces odour – if it is released slowly you probably do not smell them. When you are hot composting and they are released quickly you do. We call it the boiled cabbage odour. It is preferable to filter hot compost odours before they leave the heap. We tend to call this a bio filter – and they are normally made form materials like charcoal and compost.
Protect from vermin and flies – you need to enclose the heap in a protective enclosure that that will prevent odour leaking out. If the odour is released then vermin and flies will be attracted. So you have to enclose the heap, and yet keep the aeration flowing through!
At the start we asked can we add more. Well if it is breaking down faster the bin will compost more. But there is another aspect – hot composting in a bin allows us to compost all food waste. Let me describe what we mean by “all” A couple of years ago, WRAP under the Love food, hate waste’ banner, did a huge study, It was something like 10,000 homes; they collected the black bag (general waste with food in) and took it away. A brave group of workers unloaded, took out, weighed and measured every piece of food waste to create a big long list. They found a huge 7.2 million tonnes of food waste was sent to landfill – about 250 Kgs for every household in the UK. Most of this was unnecessary waste (poor planning on sell by dates etc). Within the list of items we then went through and identified if it was recommend to add to compost heap (cold). About 65% of the items are on the “do not add” list – think about these items – meat, fish, bones, rice, pasta, bread, cakes – a vast amount of the food we waste is on the out list. With a correct hot composting bin, you can compost a whole lot more.
Now let us think about the garden waste. Has anyone dug up all the weeds, composted them used the compost only to find a lovely patch of weeds where the compost has been used? A few of you. Weeds seeds (and a few others seeds) tend not to be broken down in cold composting – so you replant them in natures best growing medium. In hot composting seeds breakdown – se we can add more weeds even difficult stuff like couch grass – as long as we get the high temperatures.
What about grass treated with weed killer herbicides? OK good to see not many using weed killer. If you read a lot of advice it says do not compost grass. People take it down the recycling centre – guess what they compost it! Herbicides break down in composting – faster in hot composting. So if the instructions say 12 months before using compost, you are on the safe side if grass composted at 60C and it has been in for 90 days.
The last item on our list was – is it better for the environment? Well if we have anaerobic digestion we get methane and that is 24 times worse than CO2 for the environment. It is great if we have large scale AD where the plant collects all the methane and uses it for energy, but not if we have anaerobic piles or landfill piles.
If we can compost all food waste we no longer have to collect – so we save on fuel and transport and landfill.
Summary – is it worth it
It is not easy to create via DIY techniques a domestic hot composting system that controls all 5 virtuous items and stays hot with relatively small amount of food waste through winter. If you have lots of garden waste (not food waste) you can create big hot heaps, but it takes a lot of effort to turn it.
Most food waste comes in small amounts each week all through the year. We think you need a specialist hot composting bin to handle this. The HOTBIN was specifically designed to achieve HOT composting to allow ALL Food Waste to be composted.
RUNNING AT 20-40C
My HOTBIN is running at 20-40C, is it OK?
HOTBIN is very proud of its ability to hot compost at 40-60C. We “go on” about it all the time that given the right amount and mix of waste all customers can hot compost. However there are HOTBIN customers who love the HOTBIN and are happy to leave it trundling along at 20-40C.
And it is perfectly alright for HOTBIN customers to choose to bask in a ‘warm glow’ rather than sit in the ‘blazing heat’! Some of our customers know they will be warm composting through winter until they get more garden waste.
However here is the key Top Tip to remember:
If you want to ‘warm’ compost rather than ‘hot’ and still add ALL food waste you need to take extra care to ADD MORE shredded paper/corrugated cardboard and bulking agent than normal. Less water will leave the HOTBIN as steam, so you need your mix to have more dry material (paper) and ensure it stays aerated (bulking agent). If you don’t there is a real chance that you could end up with a soggy anerobic HOTBIN.
So now you know you need be strict about ADDING MORE shredded paper/corrugated cardboard and bulking agent than normal you can just sit back, relax but remember:
- Seed destruction will be less
- There is a slightly higher risk of fruit flies (they are harmless!)
- It will take longer to destroy pathogens, herbicides and pesticides (you may not have use or have any, so it could be irrelevant
- It will take longer to create you compost – so be patient, but relax – speed is not what everyone needs
Here’s a quick refresh of compost speeds and temperature:
Even when you are taking a relaxed WARM not HOT approach remember for every 10C above the external air, your compost will still decompose twice as fast as an open heap running at ambient air temp.
The things you need to watch out for when the temperatures in the HOTBIN are between 20-40 C.
Flies, maggots and fruit flies
There is a slightly higher risk of fruit flies and maggots from house flies.
- Temperatures below 40C will not kill maggots (flies can lay eggs in the food in your kitchen caddy, on garden plants etc.
- If you get an infestation either leave them be, or be patient – they will die of in winter, and you will be able to hot compost again in spring if you have grass / nettles / comfrey and more easy to digest material available in the garden.
Pathogens, herbicides and pesticides
It will take longer to destroy pathogens, herbicides and pesticides (This could be irrelevant if you have not used them – see full pathogen blog)
- Herbicides & pesticides – follow mfg guidelines – all info assumes cold composting, so if it says leave six months – leave a batch to stand for an extra couple months in bags
- Pathogens – it is defiantly safer to compost meat, fish etc at higher temperature. If you decide to warm compost, the key is to keep the waste aerated. You will lose less water as steam and see more leachate. Compensate with MORE bulking agent and more shredded paper- – keep the mix drier than normal.
Some seeds (eg tomato, melon, weeds, grass) are likely to survive when composted below 40C so they can germinate when compost is used.
- Ease the problem – do not add weeds that have seeded – get them into the HOTBIN early as greens.
- Does it really matter if a bunch of tomatoes seeds sprout where you used the compost. Pull them out and add to compost heap.
- Take extra care with invasive weeds. Do not add them to a bin operating warm – consider burning them
Bottom line – Compost
If you have any queries about warm composting in the HOTBIN or you just want to try and get into the hot composting zone between 40-60C, then please contact the HOTBIN team and we will work with you to get you hot composting.
Even if you do not have enough waste, there are often very simple solutions like taking in your neighbours kitchen caddy, stocking up with shredded paper and a bucket of chicken pellets, etc.
The bottom line – given a your compost a little longer as after all the compost coming out from a warm heap will be good for your garden!
WHY COMPOST FOOD WASTE
Benefits of composting all food waste – is it worth it?
Why compost food waste?
An estimated 7.2 million tonnes of food waste is collected by UK Local Authorities and sent to landfill. This is approximately 150-250 Kg per household per year (ref. WRAP, 2011). Around 7m UK homes already home compost, but they compost as little as 35% of their total food waste – typically adding vegetable peelings and tea bags. The other 65% of food waste (plate scrapping, meat, fish, cooked food, rice, pasta, leftover bread, cakes, etc) is on the “do not add” to your compost bin list. This advice is well founded when cold composting food waste as it often results in odour, vermin, yuck and mess (ref Defra funded, Brook-Lyndhurst 2008).
Successful home composting of all food waste has environmental benefits as it reduces fuel used to collect and transport waste to landfill, prevents methane release in landfill, [methane is a potent greenhouse gas] and reduces the number of new industrial composting / anaerobic digestion plants required in the UK.
WHAT SAVIINGS does this TRANSLATE into?
A quick estimate is 250Kg/house x 65% x 7m households upgrading to hot composting = 1.12 million mt of food waste diverted from landfill. This equates to roughly 50 large scale AD/IVC central plants. Whilst costs vary, this is around £500 million of capital costs and 10 years of planning and building.
We clearly have a vested interest, but it would appear to be a good environmental case to subsidise the more expensive “all food waste compost bins” for those households that want them. If the government exempted the compost bin from VAT (£25) and matched 3 years of food waste collection cost (£20/yr/hh for FW), then that would get to around a £75-85 subsidy!
(No VAT? – Within the overall UK energy & environmental programme there are a number of energy saving devices classified as zero rated VAT goods. So if we lobby politicians along the lines of “what’s the difference between energy saving and saving the environmental impact of transport/landfill/building AD processing facilities)
We need to get a couple of council officers thinking £75 subsidy. At a price point of £75 per HOTBIN we know people would buy on mass. From here it is a virtuous circle – high volume production reduces costs, which means lower prices which equates to more volume. We are miles away from this – but our goal has to be large scale diversion!
It’s a big lobbying task, but the rewards could be large.
Just for clarity – we are not anti the WRAP/government strategy to build anaerobic digestion (AD) plants to extract energy from food waste. Technically sound and matches the council’s need to build solutions that cater for most of the population. Composting is not going to work for all (flats, no gardens etc come to mind). At best composting is relevant for 20-30% of households, but this 20% can make an immediate and large impact winning time for the planning consents and large AD facilities to handle the other 80%.
My Council Collects food waste in Kerbside containers –
Is it still worth composting?
Some Local Authorities collect and transport food waste to either a large composting or anaerobic digestion processing plant – well done your council. To meet UK commitments on landfill diversion, we estimate 300 new reprocessing plants will be needed across the UK. Each will cost many millions to build and take many years to fully commission.
Processing at home can start immediately; it saves labour, transport costs and the need to build as many reprocessing plants. If you have very little waste (less than 2.5Kg, or a small 5 litre kitchen caddy per week), or have no garden to use compost, then using a kerbside collection makes sense.
My Council Offers cheap/free dalex/plastic compost bins –
Is it worth using a HOTBIN?
We believe so. The key issue we see is this – almost all compost advice sites (government, user, expert) will state: “do not add cooked food, meat, dairy, fish, bone etc to a traditional cold dalex type composter – the food is likely to decay anerobically and generate odour which in turn will attract rats and flies”.
1) This means around 65% of food waste items are not added to a coldcomposting bin
2) You only get significant diversion if home composting can handle all food waste
3) You need a special food waste compost bin to handle all food waste
In our opinion, as soon as you establish an objective like ‘compost all food waste with low odour, without attracting rats or flies’ or ‘compost using an easy recipe; ‘compost faster’; ‘compost all year round’ then you need to look at ‘hot composting’.
You can find a full list of the benefits of hot composting and how to evaluate a specialist HOTBIN over a traditional heap at our post on choosing the right compost bin.
Things to consider unclude;
- Do you want to make a more positive contribution to the environment?
- Recycling all your food waste so your local council no longer has to collect and transport it to landfill or a central AD/IVC reprocessing plant?
- Are you just fed up with allocating more and more of your flower or vegetable patch to overflowing compost bins that never seem to do anything?
- Do you only have seasonal waste, or do you also have regular weekly amounts of food waste all year round
You will find a full list of the benefits of hot composting over cold composting at this post
My Council Collects Green waste –
Is it still worth composting?
Many councils charge for green garden waste collection (e.g. £20-30 per year) and these charges are likely to increase. Many green bins are collected near empty (wasting time and fuel). Most of the time they are filled with mainly grass – grass is really easy to compost!
If you are a keen gardener, more than likely you will buy fertiliser, peat and/or compost to maintain the quality of your garden. Why not make your own compost and fertiliser. It takes no more effort and you could save you money.
Why is COMPOST & Composting Important?
Most gardeners just ‘know’ compost is good – they use it and they see the benefits in terms of plant growth etc.
Perhaps less well known is that humus (see definition below) is absolutely critical to soil structure, tilth, fertility, etc. It is hard to grasp just how many aspects of life on earth are linked to humus – agriculture, sustainable agriculture, reduction in inorganic fertilisers, peat, carbon sequestration, biochar, desertification, land rehabilitation, the list goes on.
So just an opinion – humus is hugely important.
Soil chemistry books are well reviewed on Wiki etc. However we do think it is helpful to clarify that humus as defined in soil science has a different meaning to the more colloquial gardening use of the term where it often used as another name for compost. In soil science, humus is a distinct fraction of the soil organic matter (SOM). Humus is:
- Dark (almost black), mushy, sticky and watery
- Is a colloidal mass, ie it holds many times its own weight in water – squeeze humus and water will come out.
- The water in humus dissolves and holds the critical plant nutrients (NO3- nitrate ion, ammonium ion (NH4-), Sulphate ion (SO4-). As soluble ions, roots easily absorb them. The ions are not easily washed out (leached out). In humus, both water and the soluble ions are retained but are ‘plant available’, ie absorbed via plant roots
- Humus has the capacity to hold and exchange cations (e.g. metal ions such as so sodium, calcium, aluminium, iron). Soil cation exchange capacity “CEC” affects fertility – CEC increases as you move from poor soils (e.g. heavy clay) to good (e.g. rich loam). Adding humus increases soil CEC, i.e., soil fertility.
- Humus is highly resistant to further mineralisation (decomposition). It is routinely carbon-14 dated at 200-500 years old
- Humus is made of large polymeric chains. However, when extracted for chemical analysis, it has the following constituents: humeric acid, fulvic acid and humin. This family of ‘aromatic ring compounds’ are used as ‘building blocks’ linked in many different ways to create a complex polymeric substance.
‘Mature compost’ is not ‘humus’, although it will contain humus. The more humus in your compost the better for your plants, soil and the environment. There is an awful lot of soil fertility and soil science that indicates humus is one of the most important items in soil fertility. Nutrients from decay end up in the soil at some stage. These nutrients are retained and made available for plants via humus. It is a sad and growing fact that nitrates and other nutrients added to soils tend to leach very quickly from soils with low humus content.
So if you are keen to get hot composting take a look through this blog or visit our website which also has a substantial composting FAQ
Out and about with the Master Composters
HOTBIN has been working with Master Composters and Recycling Officers for the past 12 months. We donated 15 HOTBINS to be used with various teams across the country. We were keen to get the Master Composters to try the HOTBIN and see how it compared against the other composting bins they work with.
HOTBIN composting is quite different from traditional composting methods and we knew Master Composters would definitely put the HOTBIN to the test!
What do we want to achieve via the HOTBIN project?
WRAP( July 2011) estimated there are around 7 million homes in the UK composting. About 65% of household food waste is classed as “do not add to compost bin”. Most composting is therefore adding 35% comprising mainly of vegetable peelings and tea bags from the kitchen. The HOTBIN can compost ALL food waste including meat and cooked leftovers.
If we can upgraded all home composters to compost all food waste, then that would divert an additional 1.12 million tonnes from landfill and collection. (250Kg/house x 65% x 7m households = 1.12 million mt of food waste). This equates to roughly 50 large scale AD/IVC central plants. Whilst costs vary, this is around £500 million of capital costs and 10 years of planning and building.
We clearly have a vested interest, but we think there is an environmental case for councils to subsidise the more expensive “all food waste compost bins” for those households that want them. If the government exempted compost bins from VAT (£25) and matched 3 years of food waste collection cost (£20/yr/hh), then that subsidy would allow a price point of £75 per HOTBIN! The subsidy leads to a virtuous circle – more units leads to high volume production, which reduces costs, which reduces prices again which increases volume which diverts even more. We are miles away from this – but our goal has to be large scale diversion. (If you want to read more on the benefits of hot composting topic jump to this post).
This year will see HOTBIN enter all the major Council framework agreements (ESPO/YPO/Scotland Excel) giving us more visibility and opportunity to discuss removing food waste via home composting. With the help of Recycling Officers and Master Composters we hope to divert more food waste in 2013.
HOTBIN test SITES include:
||What & Why
||2 units with Waste Recycling Officers
||4 units, 2 with Master Composters & 2 with Recycling Team
||1 unit with Waste Minimisation Officer
||1 MC – Sarah, aka ‘Compost Woman’ Follow her blog and review here
||1 unit with Master Composter
||On display Snibston recycling centre
||1 unit with waste recycling Officer
||1 unit with MC
||1 unit with MC
||1 MC & 12 Units with Waldringfield Community Composting
||1 unit with MC
||1 unit with MC
||2 Units, on display at York Rotters See St Nicks field website
|Zero waste (Scotland)
||Waste Recycling Officer
|If you would like contact details for the above, please email us at firstname.lastname@example.org
REMEMBER MASTER COMPOSTERS;
- Already use many different composting systems
- Work with many different users from novice to expert
- Have undergone formal compost training and accreditation
So What Do the Master Composters say ABOUT THE HOTBIN?
Jane Griffiths, MC Network Manager: The HOTBIN processed a very challenging food waste mix into compost after 90 days. During the trial we were really impressed that when checking the temperature it read 60°C when the outside temperature was around 10°C.”
Lesley Tulitt, Buckinghamshire: I got the bin going and have not looked back. The time of year is irrelevant, as the key point is to introduce a large amount of fresh greens like grass clippings which start the process and then keep adding waste every few days to maintain the temperature. As long as you keep feeding it with material it works. (Lesley recently blogged at http://recycles.buckscc.gov.uk/).
Sue Baines, Oxfordshire: The HotBin website is fascinating, I can spend hours looking at it when I think I should really be gardening, but it’s good to have access to so much information. I received the straps a couple of weeks ago and they do seem to help to hold the hatch in place. I’m still having problems with leachate, although not as much as before. …The compost in the bottom of the bin was extremely compressed and wet and seemed anaerobic and smelly although it was mainly composted…. Having said all that, I’m still getting good quantities of reasonable compost out of the bin, so I’m not complaining.
Sarah, Herefordshire (see Compost Woman – blog): I filled the bin mid afternoon on a sunny but cool day (18C). After 24 hours the top layer of material was at 50 Celsius with an ambient temperature of 20 Celsius. It was very easy to load the HotBin and so far I am impressed with the ease of use. I am also VERY impressed with the comprehensive and user friendly information on the HotBin website – especially the FAQ pages, which are full of all sorts of useful information about composting.
Rod Weston, Leicestershire (HOTBIN at Snibston Discovery Museum): The bin is attracting a lot of interest, particularly the external thermometer just about everyone has to open the lid to confirm that it is hot (60-70C) inside. We are using it to compost food waste from the on-site cafe so it is a bit of a challenge but the bin is performing well.
Betsy Reid, Suffolk: I am the satisfied owner of a HOTBIN. What I am now wondering is whether you could offer any price reduction for a Community Composting scheme?
(We did and Waldringfield is our first community Composting scheme with 12 HOTBINS last year and another 12 HOTBINs to be delivered in March 2013!).
Linton Waters, Shrewsbury: Having now experienced the HOTBIN, I’d be very happy to talk positively to members of the public at events etc and recommend it where it seems appropriate.
Hugh Baker, Compost Works, Mole Valley: Thanks for the HOTBIN – Very impressed with it.
Lessons learnt with Master Composters
Our first year has flown past, but not without challenges. Our policy is to learn and fix problems as soon as possible. Here’s a short review of issues and fixes that came up from the Master Composter testers:
Bulging doors and straps: The first batch of HOTBINS had some hatch panels that appeared to slip. We supplied cam straps to all existing and new customers and subsequently made a design revision which solved this problem.
Rats: MCs know rats can get into just about any compost bin – plastic, wood or metal. They always ask: Is it rat proof? No, but 99.5% of all customers report no issue with rats. The key defence against rat attack is the removal of odours that attract them – the HOTBIN achieves this – you can read more on rats by jumping to our rat FAQ post.
Not getting warm: a small percentage of all customers struggle to get into the hot composting zone. The % of MC who struggled was no different to customers. We solved each incident and have got them going. The causes are usually human factors (prior experience cause skipping key steps – like adding plenty of bulking agent when adding food waste or not adding enough chopped cardboard or shredded office paper with wet waste) or practical (not enough waste).
Leachate & avoiding excess water: If the mixture is too wet – leachate (brown water) comes out of the base. We now:
- Plan for occasional leachate – and ask users to check location of HOTBIN
- Advise how to minimise leachate by adding shredded cardboard or office paper to waste
Flies and maggots: A hot HOTBIN working above 40C kills flies, maggots and other critters. One MC spotted an infestation of fruit flies. We advised how to get hot composting and the flies disappeared.
Emptying: It could be easier – but also noted no harder than other compost bins.
Bulking agent, food waste and how to handle food waste: of all our challenges taking trained composters who know you should not add food waste to a compost bin and asking them to do it was hardest. Very few are trained in compost engineering and hence the theory and practise of using bulking agents and hot airflow. What we ask is counter intuitive too many aspects of cold composting – but when they get it and see it working there is an addiction and smile that at last composting can be fast and fulfil its potential for recycling.
For more information on the HOTBIN please call the HOTBIN team on 0845 6210095
We can also arange 12 HOTBINS for a community composting group purchase, you just need to find 12 friends who want to compost all food waste!
For bulk pricing and sales to Councils, please call Straight plc 0113 245 2244
WOOD CHIP – Bulking Agent
Compost bulking agent – what is it and why do I need it?
We have already mentioned a little bit about Bulking Agent in a previous post and STRESSED that it is an essential part of the HOTBIN composting mix. It aides hot composting by helping to retain a structure which helps get oxygen that the bacteria.
You need to add bulking agetn (wood chip) when you are composting ALL food waste but it never goes amiss if you are trying to boost those temperatures into the hot composting zone between 40-60 C.
So what is a composting Bulking Agent?
Well it is simply composted wood chip. Basically raw wood chip that has been left in a pile for six months. It has the advantage in that it will have bacteria on each chip which will mean it acts as a natural accelerator too.
Can I use raw wood chip?
Yes, you can use raw wood chip. It will still create the necessary aeration structure to allow the chimney effect needed to supply the bacteria with vital oxygen. Those that have been feeding in their shredded Christmas tree have noticed that their HOTBINs have achieved good temperatures due to improved aeration!
The HOTBIN with extras comes with a 25L starter bag of composted wood chip so there is no delay in getting started once your HOTBIN arrives. We estimate you will use at least 75L of Bulking Agent or Wood Chip every six months.
Remember you can easily make your own or find out from your local council if you can get your hands on some for free.