Jump to content

To compost or not to compost - The long read


Dr Bob

Featured Posts

4 hours ago, tree monkey said:

Bob is talking about hot composting, done properly it is very effective at killing the pathogens in the base materials.

 

In that case I revise my question. How would one know if said hot composting has been done properly? 

 

What does "done properly" mean exactly, to a hopefully open-minded layman like me who is half considering a composting bog but never seems able to find proper, fully satisfactory answers to my reams of doubts? 

Link to comment
Share on other sites

1 minute ago, MtB said:

 

In that case I revise my question. How would one know if said hot composting has been done properly? 

 

What does "done properly" mean exactly, to a hopefully open-minded layman like me who is half considering a composting bog but never seems able to find proper, fully satisfactory answers to my reams of doubts? 

 

It will look and,smell and feel very much like garden soil that has been worked and dressed with compost for many years. I suggest you don't feel it until you have inspected and smelt it first. However I am far from convinced it is that easy to do hot composting on a boat. Garden-wise the usual minimum size of the heap is said to be 1 cu. yard/meter. However my BiL's so called hot composters are smaller and do no such thing as far as I ca see, they just cold compost. Parts of my compost bins do get hot in places and at times,  usually after grass clippings have been added, but I have never felt uncomfortable hand heat and am not sure it would be hot enough to destroy human pathogens. I think to do hot composting of human waste I would temperature logging unless I could be sure the complete compost will never be used on food crops.

Link to comment
Share on other sites

1 hour ago, Jerra said:

I have two questions.

 

1.  You say you used the compost for pots twice a year.  This implies that at times the pots are emptied to be filled with new compost.  So what do you do with the "old" compost from the pots.

 

2.  I think organic must mean something different to you than it does to me.  You said "i think the key here is that the 'highly organic waste' is no longer highly organic after composting."   Are you implying the material somehow changes state from having organic origins to not have organic origins?

The old compost in the pots goes on the marina's compost heap.

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2. In the lab, the main test to determine if something is biodegradeable (ISO 14855) is to put the test specimin in an oven at 58°C for 6 months and measure the amount of CO2 that is given off. A product is said to be biodegradable if 90% of its carbon is converted to CO2 ie there is very little organic component left. This is why the product going into the composter may be highly organic but the product out is totally different. It is not human poo anymore. Now most food waste (and hence manure) is a complex mixture of Carbon, nitrogen and oxygen - especially if plant based - so it all doesnt disappear as CO2, only the predominantly CH2 bits of it (ie the long chain fatty acids, the triglycerides etc etc). I dont know what the cellulose type molecules get up to (the ones built on lots of C,N and O). Its too complex. If you do any digging, let me know.

That is aerobic composting. If you look at anearobic digestion, a different set of bugs operate with instead of turning the CH2 chains to CO2, turn them to CH4 (methane) and other organic species such as acetic acid.

  • Greenie 1
Link to comment
Share on other sites

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2.

 

 

So, we are all trying to cut the CO2 emissions to reduce the climate change, but the Composters are releasing more CO" into the atmosphere.

 

Maybe that's why these composters buy electric cars - to balance out their CO2 emissions !

  • Greenie 1
Link to comment
Share on other sites

I see no harm putting it in the fire with the ladle. 

 

At least you get a bit if heat out of it which at this time of year is actually quite useful. In summer use the freezer and the cannon or the trebuchet.

 

Shoulder seasons are more complex. 

Link to comment
Share on other sites

3 minutes ago, Alan de Enfield said:

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2.

 

 

So, we are all trying to cut the CO2 emissions to reduce the climate change, but the Composters are releasing more CO" into the atmosphere.

 

Maybe that's why these composters buy electric cars - to balance out their CO2 emissions !

 

 

I don't find your sniping in this thread helpful, where people are trying to discuss this in a grown up way.

  • Greenie 2
Link to comment
Share on other sites

10 minutes ago, Tony Brooks said:

 

It will look and,smell and feel very much like garden soil that has been worked and dressed with compost for many years. I suggest you don't feel it until you have inspected and smelt it first. However I am far from convinced it is that easy to do hot composting on a boat. Garden-wise the usual minimum size of the heap is said to be 1 cu. yard/meter. However my BiL's so called hot composters are smaller and do no such thing as far as I ca see, they just cold compost. Parts of my compost bins do get hot in places and at times,  usually after grass clippings have been added, but I have never felt uncomfortable hand heat and am not sure it would be hot enough to destroy human pathogens. I think to do hot composting of human waste I would temperature logging unless I could be sure the complete compost will never be used on food crops.

I think this is the problem. The normal Jo in the street will not believe composting is possible because of their experiences in composting garden waste. Exactlly where I was 3 years ago. However now having seen close and personal these mini hot bins (circa 50L volume) generating 60°C + in 2-3 days and holding it up there - and seeing how we do our lab tests keeping samples up in the 50/60°c range and them fully composting down in weeks, you start to understand what composting really is and how it works. Industrial composting works in 12 weeks. Fact. We cant do it that fast on a boat but 6 months is possible.

25 minutes ago, MtB said:

 

In that case I revise my question. How would one know if said hot composting has been done properly? 

 

What does "done properly" mean exactly, to a hopefully open-minded layman like me who is half considering a composting bog but never seems able to find proper, fully satisfactory answers to my reams of doubts? 

Properly means that you compost until all the material that can be composted is eaten by the bugs. When there there is no food to be consumed by the bugs, then the material is said to be fully composted. The Rottegrad scale is used to determine completion of composting.  An alternative is to measure the volatile fatty acid concentration of a compost and it must be below the set value (meaure via ion chromatography of an aqueous extract). We do this in the lab. It is pretty obvious though that you can visually assess it as well.

  • Greenie 2
Link to comment
Share on other sites

7 minutes ago, Alan de Enfield said:

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2.

 

 

So, we are all trying to cut the CO2 emissions to reduce the climate change, but the Composters are releasing more CO" into the atmosphere.

 

Maybe that's why these composters buy electric cars - to balance out their CO2 emissions !

Whatever you do with poo emissions are going to happen! Some sooner than later Alan :lol:

Link to comment
Share on other sites

Just now, Dr Bob said:

I

Properly means that you compost until all the material that can be composted is eaten by the bugs. When there there is no food to be consumed by the bugs, then the material is said to be fully composted. The Rottegrad scale is used to determine completion of composting.  An alternative is to measure the volatile fatty acid concentration of a compost and it must be below the set value (meaure via ion chromatography of an aqueous extract). We do this in the lab. It is pretty obvious though that you can visually assess it as well.

 

Ah yes, now there's another question. What bugs? What if they don't notice the composter full of poo-food and the process never begins? Is it a bit like keeping the sourdough starter going?

 

This may seem like a banal question to someone experienced with composting bogs but I'm not likely to shell out a four figure sum for one until I feel confident I understand everything about them and how its done.

 

 

 

 

Link to comment
Share on other sites

24 minutes ago, Dr Bob said:

The old compost in the pots goes on the marina's compost heap.

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2. In the lab, the main test to determine if something is biodegradeable (ISO 14855) is to put the test specimin in an oven at 58°C for 6 months and measure the amount of CO2 that is given off. A product is said to be biodegradable if 90% of its carbon is converted to CO2 ie there is very little organic component left. This is why the product going into the composter may be highly organic but the product out is totally different. It is not human poo anymore. Now most food waste (and hence manure) is a complex mixture of Carbon, nitrogen and oxygen - especially if plant based - so it all doesnt disappear as CO2, only the predominantly CH2 bits of it (ie the long chain fatty acids, the triglycerides etc etc). I dont know what the cellulose type molecules get up to (the ones built on lots of C,N and O). Its too complex. If you do any digging, let me know.

That is aerobic composting. If you look at anearobic digestion, a different set of bugs operate with instead of turning the CH2 chains to CO2, turn them to CH4 (methane) and other organic species such as acetic acid.

Thank you.  Much clearer now.

17 minutes ago, Alan de Enfield said:

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2.

 

 

So, we are all trying to cut the CO2 emissions to reduce the climate change, but the Composters are releasing more CO" into the atmosphere.

 

Maybe that's why these composters buy electric cars - to balance out their CO2 emissions !

The CO2 is going to be released however the waste is dealt with I suspect.  IIRC the usual sewage treatment works gives off CO2

Edited by Jerra
  • Greenie 3
Link to comment
Share on other sites

My only problem with composting  toilets is storing the stuff whilst its composting, I wont have any  boxes or flower pots on the roof and since its a trad stern there is no room there either. Also the disposal, what do I do with it once its composted  if I don't have a garden?

 

  • Greenie 1
Link to comment
Share on other sites

1 hour ago, MtB said:

 

Ah yes, now there's another question. What bugs? What if they don't notice the composter full of poo-food and the process never begins? Is it a bit like keeping the sourdough starter going?

 

This may seem like a banal question to someone experienced with composting bogs but I'm not likely to shell out a four figure sum for one until I feel confident I understand everything about them and how its done.

 

 

 

 

Mike,

I dont know enough about the bugs to answer you question properly, other than they are everywhere.

When we do a fragmentation test, ie to see if a bit of plastic packaging is compostable, we cut some 10cm pieces of film up and put it in something that is very like one of the mini hot bins, charged with 50L of 'feed'. The food is chosen to work the bacteria hard for the 12 week cycle. We mix up the feed - usually a blend of food waste, paper, card, and other stuff (ie a blend of green and brown) and put it in the bin. Always, 2-3 days later the temp is up at 60°C with the bugs chomping away. I dont know what the bugs are but they are always there. They are in the food. They are on the paper. We always put in 1-2Kg of aged manure (but less than 2 months old). This is all done accurately with a known recipe. It always gets to temp even without the manure.

I guess it is nature. Leaves fall from the trees and biodegrade. That is the bugs in action.

Keeping sourdough is not that easy as it takes a while to get going and you need to keep it at the right temperature. This 'reaction' is much quicker but yes, is essentially the same. The bugs are all around us.

  • Greenie 2
Link to comment
Share on other sites

4 hours ago, MtB said:

 

Ah yes, now there's another question. What bugs? What if they don't notice the composter full of poo-food and the process never begins? Is it a bit like keeping the sourdough starter going?

 

This may seem like a banal question to someone experienced with composting bogs but I'm not likely to shell out a four figure sum for one until I feel confident I understand everything about them and how its done.

 

 

 

 

Temperature is the way to monitor how well the process is working, Bob is suggesting 60 degrees from his lab work, so that seems reasonable, so say 60.degrees for 2 weeks, maybe Bob can give a more accurate time scale for full composting

 

I have a slight issue with this, i am slightly skeptical that this temp can be achieved in an small uninsulated box in winter, I think the "hot box" composters are insulated to facilitate this but as I remember volume of material is also important, again maybe Bob can give some help with this.

 

In garden composting the bugs are provided by contact with the surrounding soil/environment plus existing bugs already in the material, as bog material is isolated from soil I suspect the bugs used to start the process are already in the material to some extent, plus some must come from the atmosphere, which suggests washing of the primary box, as someone previously asked about would be actually a bad thing for the process, as the box would now be inoculated, so yes much like a sourdough :)

 

5 hours ago, Dr Bob said:

I think this is the problem. The normal Jo in the street will not believe composting is possible because of their experiences in composting garden waste. Exactlly where I was 3 years ago. However now having seen close and personal these mini hot bins (circa 50L volume) generating 60°C + in 2-3 days and holding it up there - and seeing how we do our lab tests keeping samples up in the 50/60°c range and them fully composting down in weeks, you start to understand what composting really is and how it works. Industrial composting works in 12 weeks. Fact. We cant do it that fast on a boat but 6 months is possible.

Properly means that you compost until all the material that can be composted is eaten by the bugs. When there there is no food to be consumed by the bugs, then the material is said to be fully composted. The Rottegrad scale is used to determine completion of composting.  An alternative is to measure the volatile fatty acid concentration of a compost and it must be below the set value (meaure via ion chromatography of an aqueous extract). We do this in the lab. It is pretty obvious though that you can visually assess it as well.

I suspect this is where the confusion over the use of the word organic is happening, you are using a defined scientific term, those of us who approach this with a more dirty hands experance would still use the term to describe the results of a successful compost heap, although from a soil science perspective the produce from a compost heap is  considered organic, as opposed to the the inorganic ingredients already present in the soil (sand,silt,clay)

 

Edited by tree monkey
Link to comment
Share on other sites

8 hours ago, tree monkey said:

Temperature is the way to monitor how well the process is working, Bob is suggesting 60 degrees from his lab work, so that seems reasonable, so say 60.degrees for 2 weeks, maybe Bob can give a more accurate time scale for full composting

 

I have a slight issue with this, i am slightly skeptical that this temp can be achieved in an small uninsulated box in winter, I think the "hot box" composters are insulated to facilitate this but as I remember volume of material is also important, again maybe Bob can give some help with this.

 

In garden composting the bugs are provided by contact with the surrounding soil/environment plus existing bugs already in the material, as bog material is isolated from soil I suspect the bugs used to start the process are already in the material to some extent, plus some must come from the atmosphere, which suggests washing of the primary box, as someone previously asked about would be actually a bad thing for the process, as the box would now be inoculated, so yes much like a sourdough :)

 

I suspect this is where the confusion over the use of the word organic is happening, you are using a defined scientific term, those of us who approach this with a more dirty hands experance would still use the term to describe the results of a successful compost heap, although from a soil science perspective the produce from a compost heap is  considered organic, as opposed to the the inorganic ingredients already present in the soil (sand,silt,clay)

 

I start my composting in the toilet I add veg matter straight into the mix. I also get manure from the farm which goes in the bins at the allotment and the raised beds, its sat on top of the cardboard currently keeping the weeds away!

Link to comment
Share on other sites

Just now, tree monkey said:

I'm about to start a similar job, although I do have access to massive amounts of 30yrs of very well rotted horse muck

 

Ours is a mixture of cow and horse muck. I had a tractor load delivered to the allotments it went in days! The man in charge was on holiday and missed out :lol:

Link to comment
Share on other sites

13 hours ago, Alan de Enfield said:

 

The bacteria that biodegrade the 'food' breakdown the long carbon chains releasing CO2 into the atmosphere. Therefore a highly organic feed becomes less organic as it is loosing CO2.

 

 

So, we are all trying to cut the CO2 emissions to reduce the climate change, but the Composters are releasing more CO" into the atmosphere.

 

Maybe that's why these composters buy electric cars - to balance out their CO2 emissions !

We can't live without producing and relying on CO2, the idea it must be seen as a pollutant on a small scale line this is just nonsense. 

  • Greenie 2
Link to comment
Share on other sites

8 hours ago, tree monkey said:

Temperature is the way to monitor how well the process is working, Bob is suggesting 60 degrees from his lab work, so that seems reasonable, so say 60.degrees for 2 weeks, maybe Bob can give a more accurate time scale for full composting

 

I have a slight issue with this, i am slightly skeptical that this temp can be achieved in an small uninsulated box in winter, I think the "hot box" composters are insulated to facilitate this but as I remember volume of material is also important, again maybe Bob can give some help with this.

 

 

390077836_Screenshot2023-01-09at09_54_49.png.ba3e6b411972eaacdf24a2fefdf2f8a2.png

 

 

 

2052566570_Screenshot2023-01-09at09_54_49.png.e72e94258bf474765ec5e45baaabf226.png

 

Above is an extract from the ISO 16929 test method (EU standard) for the temperatures that have to be used when doing the fragmentation test for industrial composting. The temperatures are deemed by the standards body to represent what happens in an industrial Windrow compost heap (but that's another story).

In our lab test we have units similar to the mini hot bins operating for the 12 weeks of the test at this temperature. Everything that is used by industrial composters is fully composted after 12 weeks at these temperatures - note most of them avoid anything man made like cups, plates, wet wipes even if they are stamped compostable.

 

These temps CANNOT be sustained in a small uninsulated box. You can achieve them easily in an insulated 50-100L box but only if you feed them regularly ie twice a week. This is the basis of the mini-hot bin. Go to their web site and see how they work. They do work on boats but you need to feed them kitchen waste as you wont have enough poo to feed them so you then end up with loads of great compost - but what then do you do with it. Our 120L a year is fine for our pots but I guess with a hot bin you'd make over 300L a year. Keeping the temp up at these levels is easy with a hot bin.

 

For us mere mortals trying to compost smaller quantities ie 20-40L in an uninsulated box, you will never achieve any real temperature rise, so using the boat roof as a radiator between April and October is the answer to get the material up to 50-60°C to assist in killing the pathogens (along with time) - see the humanmanure book. Hence the 6-9 months compost time depending on season. You also do need to get the water content right and turn it regularly - once a month - when its on the roof.

Edited by Dr Bob
  • Greenie 1
Link to comment
Share on other sites

An interesting post, Dr.

 

I know a bit about composting (but clearly not as much as you).  I'm content that composting successfully is possible on a boat and that everything you say is correct.

 

The problem is that for the average boater, it's very easy to get it wrong and any consideration of human behaviour would suggest that encouraging most composting loos will lead to unpleasant human faeces being put in bins (a bag of shit is still a bag of shit even if it's not as bad as a bag of shit and pee).  The only possible way forward is to have dedicated emptying points for this material, which is then taken away to be composted properly.  This still leaves 2 problems:

 

1.  Who pays for that?

2. What happens when the solid matter is inevitably contaminated with urine by an idiot boater?

Edited by doratheexplorer
  • Greenie 2
Link to comment
Share on other sites

23 minutes ago, waterworks said:

We can't live without producing and relying on CO2, the idea it must be seen as a pollutant on a small scale line this is just nonsense. 

It just shows the lack of inteligence in some people.

What on earth do people think happens to their poo when the flush it down the loo. It biodegrades in the system further down the line creating CO2. That is nature. DUH!

People seem to have forgotten about the carbon cycle. Plants decay and go to CO2. Living plants pick up that CO2 to help build new cells. That cycle has been going on for a few years.

  • Greenie 3
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.