KEEPING THE HOTBIN HOT
How do I keep my HOTBIN composter working hot? My HOTBIN seems to have stalled – It won’t go above 40C any more…
Here at HOTBIN composting we are passionate about our brand promise that given the right volume and mix of waste everyone can hot compost at 40-60C.
We do not have many customers who struggle, and normally a combination of our Q&A database, email support or our unique composting photographic analysis service get their HOTBIN composting on track.
You can imagine therefore we get a bit hot under the collar when we find a customer where everything seems perfect, they have been hot composting for a while, all the settings are right (valve, door on, etc) the mix is right and there is nothing obviously wrong and yet the HOTBIN suddenly sticks persistently at 30-40C and will not rise. We have termed this “a stalled HOTBIN”.
Who is affected by stalling?
Firstly this is not to be confused with customers who have never reached 60C (if this is the case, please check out the FAQ: How to get to 60C check list. Stalled HOTBINs are where it has been working perfectly for months at 40-60 then suddenly it will not rise above 40C.
This is not a common occurrence and there are only a handful of reported cases. A dedicated customer (Andy U) wrote in and suggested an adaptation to help and this kicked off a summer of activity and research.
Why does it happen?
We have identified one central issue: restricted airflow through the base layer. (Think of the HOTBIN as a fire in the chimney, you add new waste onto the fire to fuel it. As the heat rises is ‘draws’ fresh cold air in at the base. This air is drawn up through the base layer. If not enough air flows, the bacteria are restricted and hence the heat produced is restricted.
What causes restricted airflow?
The HOTBIN works under many different waste conditions. However, we have identified the causes that can tip the balance and create restricted airflow:
- Base plate is ‘plugged’ (see below)
- Ultra compressed base layer
- Dense, compressed, wet layer of either paper or grass
Top tips for fixing A stalled HOTBIN
If you are suffering from a stalled HOTBIN, here are our tips for fixing it:
- Check to see if your base plate is ‘plugged’ (check this post to understand what we mean by plugged rather than normal operation where the holes are covered with compost).
- Sprinkle a couple of handfuls of wood chip on the base plate after each emptying to reduce the chance of plugging.
- Empty out the base layer at least every 6 months. Longer and it will lead to ultra compression of the base layer.
- Always add bulking agent – this is critical with Food waste, but it will also help prevent compression of any waste
- If stalled, stir the top half of bin to help aerate and break up any dense layers.
- Check for thick layers especially in lower half bin. – eg a solid layer of wet grass or compressed wet paper.
- Check mesh plate for leakage of water/leachate. If lots of leachate cross check to see if your real issues is that your waste is “too wet” for hot composting
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.
CATERING FOOD WASTE
Is the HOTBIN an effective recycling solution for businesses producing catering food waste?
As many as 50,000* UK businesses could utilise food waste composting to tackle catering food waste. It can save the company collection and disposal costs and help the environment by reducing the need for landfill. (*50,000 businesses might divert as much as 25,000 tonnes – derived from WRAP campaign on catering food waste statistics).
Over the past 12 months, we have been working with a group of corporate sites to test the HOTBIN in a business environment. Various teams in cafes, B&Bs, hotels, and business / corporate catering facilities have been using the HOTBIN.
The sites testing/using HOTBINs include:
||Hotels, cafe, B&Bs
||Kitchen Garden, Meldon
|Rose Lodge Care Home
||BrockBrushes Farm shop
||down south garden centre
||Plants R Ross
Does the HOTBIN work on catering food waste?
Yes – this was never in doubt, catering food waste is the much the same as domestic food waste.
Can the HOTBIN cope with a catering waste sites volumes?
Yes, however, the amount of food waste varies enormously across the sites – from very small amounts barely enough to keep the HOTBIN hot, to too much and right on the limits of practical use.
Top Tips When Looking at Composting Catering Waste
Capacity: match how much food waste to to number of HOTBINs needed. Few sites know how much food waste they have, so we have developed the following chart.
|Kgs / week
(rotating one per day)
||5Kg (10 litres)(2 small, 1 large kitchen caddy)
||20 Kg (40 litres)
||35 Kg (70 Litres)
||15-20Kg (30-60L)(60 litres is a mid-sized kitchen bin)
||60-80 Kg (240-320 litres)(200 litres is a std wheelie bin, or half a 4-wheel bin)
||100-200 Kg (200-600 litres)(600 litres is large 4 wheel wheelie bin a week
Notes: weights relate to just food waste – adding garden waste will significantly change capacity.
Find a compost aware champion: hot composting needs to be actively managed. No matter how good the equipment, mishaps will occasionally happen. In a business environment, it is important to plan for these by having a member of staff ‘on call’ with the knowledge to sort problems out. Your champion may have to sort out occasional issues (eg odour if the mix was incorrect, flies or maggots if the waste was left accessible to flies and HOTBIN was not running hot).
Avoid excess water: catering food waste is often ‘too wet’ for hot composting. Staff will have limited time to check what is being collected. Behind the scenes you need to:
- Balance the mix by adding shredded office paper and bulking agent.
- Find a storage space for bags of paper and bulking agent
- Plan for occasional leachate – check where you locate the HOTBIN
- Factor in time to chop up waste: a whole cabbage will takes ages to compost –and affect HOTBIN performance. Plan in time ‘to chop’ and be aware of business conflicts – eg staff need to clear and restock shelves versus chopping waste.
Housekeeping: Any waste dropped needs to be picked up. This is vital – your site is likely to be very quite at night and no noise plus food on the ground is a ‘rat magnet’. Store all waste prior to adding to HOTBIN in covered container.
Loading routine: The HOTBIN has a minimum and maximum loading amount and it works best when fed twice a week. Plan the right collection routine and have enough HOTBINs to load based on that rota.
Emptying: empty the compost out every 3 months and take/spread it on the garden. You can load without any special kit – but emptying needs gloves, buckets trowels – it’s not an office dress task!
You may not want to use the compost there and then – in which case a storage area for ‘maturing compost’ is needed – normally a 1m3, ie a palette box is ideal
Is it worthwhile?
The test sites are demonstrating that with planning you can compost catering food waste onsite. It is still a little early to say if they have saved cost over the collection and disposal costs, but the environmental benefits by reducing transport and landfill are achieved. This is a good message around recycling and being sustainable.
Here are some items to add into your evaluation:
- Know your waste collection costs, and do not forget to add in your costs to load the wheelie bins with waste.
- The compost generated (1-3 mt) would save you perhaps £80-240/year if you compared to buying compost to spread on site gardens
- Bulking agent and browns should cost less than £40/year
- Cardboard approx £15-30/year (but free if you use office shredded paper)
- Staff time – we currently estimate 30 mins a day to load and unload 2 units
- Capital cost for HotBins (c£400), write of over 5 years
- Corporate messages – there is a great message around recycling and being sustainable. This can be extended for some into organic gardening.
- Carbon offsetting – no detailed information at present
We think as many as 50,000 UK businesses could utilise a HOTBIN. This would equate to 25,000 tonnes diverted from landfill. (Derived from WRAP campaign on catering food waste statistics).
Come on UK business – you know it makes sense – sign up today!
Research Twin packs and Quad Pack here.
It makes absolute sense for B&B’s and small hotels plus some cafes who have use for their compost! You can even compost the Vegware range of completely compostable food packaging and catering disposables as you can see in an earlier post.
One size (or even four) does not fit all. If you need a really big onsite composter do not despair, we have some big friends and we are happy to introduce you. http://www.tidyplanet.co.uk/, Ridan http://www.ridan.co.uk/, HotRot http://www.hotrotsolutions.com/
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!
Composting Know How
The HOTBIN team has reached another milestone!
The total number of composting Q&A articles has passed 100 (Dec 2013 update)
If you are unsure what you can add to your compost? Want to know how composting works? Intrigued about the benefits of hot over cold composting? And want use a Q&A source jump in and give it a go to bust some of those composting myths.
The FREE composting advice database is divided into different subject areas with posts within each section. Of course, some of these are HOTBIN specific, but a huge amount are generic answers relevant to all composting. The knowledge base is fully indexed and searchable.
If you do not find what you need, email us and once we have an answer we will post it for all to see.
The HOTBIN really does do what it says on the BIN!
Some of you may already know James is a bit of a whiz with wireless communications and has set up his own remote temperature monitoring for the HOTBIN.
The whole world can now watch his HOTBIN temperature 24/7 real time via the internet.
View his extraordinary live feed today by clicking here
This is a great resource for new customer who want to know it what is possible via real customers.
You can spot the temperature drop when he opens the lid, the reheating of the new waste, then the slow fall back as the waste is consumed.
James manages to keep his HOTBIN in the 40-60 zone most of the time but he feeds it regularly (can you can work out how often and what days!).
We appreciate not everyone is going to achieve this and we will be looking at the 30-40C users in a later post.
Join our 2013 Virtual Composting Dozen
If you are not already HOTBIN composting you can email us at email@example.com to get our ‘Twelfth Night’ promotion code. We want to create a virtual HOTBIN composting community dozen to kick start 2013.
The first 12 people to email before 5th January will receive a discount code which will reduce the HOTBIN by 27% to £109.99 each. The code expires at Midnight on 5th January.
The HOTBIN has been specifically designed to achieve HOT composting to allow ALL food waste to be composted. Cutting the amount of waste a household sends to landfill.
The HOTBIN maximises what nature does naturally by bringing together the right conditions to make hot composting easy. Compost 100% of your domestic food waste in your own backyard. This includes left over meals, plate scrapings, meat, fish, small bones, bread, cakes, pasta and rice.
What makes the HOTBIN different?
- It is a HOT composting bin that can achieve between 40-60 °C
- At these temperatures you will produce rich compost in 90 days
- Due to the hotter temperatures you can recycle more types of household waste including ALL food waste and grass cuttings
- It can be placed anywhere in the garden, the HotBin can be located on all even surfaces, in the sun or shade
- It works all year round including the winter months
The design of the HOTBIN means that rich compost can be created every 90 days without forking or tumbling. It works by promoting an environment where bacteria that decompose waste can thrive, with an effective aeration technique. Heat is generated by and is crucial to this process as it means richer compost is created faster and the HOTBIN can achieve temperatures of between 40-60 °C naturally.
The revolutionary HOTBIN composter will produce up to 75L of valuable organic material every three months as it happily continues to compost throughout the winter months.
Which means that if you start HOTBIN composting now you will have already harvested a batch by the spring.
BEST NEW COMPOST BIN 2012 TWO AWARDS FOR HOTBIN COMPOSTING
THE HOTBIN WINS TWO AWARDS ON FIRST BIRTHDAY
HOTBIN composting is celebrating its first Birthday with two awards under its belt. Just after being awarded Northumberland Green Business 2012 they were told that Grow Your Own magazine readers had voted the HOTBIN ‘Best New Product 2012’.
“To receive these two awards just a year after launching the HOTBIN makes us feel really special,” says Tony Callaghan, Managing Director. “It certainly has been a busy year helping HOTBIN users to break with some of the traditional composting dos and don’ts. It is great to know that so many people are supporting us and enjoying a more sustainable future.”
“I invented the HOTBIN as I got frustrated with an overflowing compost bin and failed to find an alternative that could compost all food waste satisfactorily together with garden waste. These awards show the ups and downs were worth it and I appreciate everyone’s acknowledgement and support for HOTBIN,” Callaghan continues.
In a recent HOTBIN survey users suggest having the ability to hot compost food waste at home has a huge impact on a more sustainable future. 90% of users agreed that it was important to have the ability to compost cooked food waste; 61.5% of users are now adding all food waste to their HOTBIN and 72.9% are now diverting a lot or nearly everything from landfill.
And as one user said “The HOTBIN quickly converts waste into good stuff for the garden whilst taking me a step further towards the good life.”
From a standing start HOTBIN will have sold nearly 2000 units by year end and has been told on good authority (the biggest retailer of compost bins) that it could easily be the best selling specialty compost bin. It has already appeared on The Radio2 Simon Mayo show, the Alan Titchmarsh Show and was declared one of the best three composting bins by The Telegraph.
The HOTBIN is made from a robust insulated engineering material to help defy Newton’s law of cooling. The unique design makes hot composting manageable by the average family in their own back yard. As the HOTBIN truly reduces heat loss you can achieve temperatures between 40-60C allowing you to recycle all food waste alongside your garden waste all year round.
The HOTBIN can help millions of existing home composters to compost ALL food waste without the inherent problems of odour, vermin and flies. Traditionally only 40% of domestic food waste goes into the compost bin, the HOTBIN can increase that to 100%, reducing the amount sent to landfill.
Bacteria in the HOTBIN Composter
Here is how you look after the bacteria in the HOTBIN to help you hot compost!