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BIO GAS (Down the Rabbit Hole we go)

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So seeing as we have been talking about Bio Gas and Bio Methane, i thought some might like to know more about what it is and how its made etc etc. Down the rabbit hole because it isnt as simple or easy as it seems, also there are different forms of Organic Digestion, alot more than maybe people realize.

As a analogy lets say a complete non driver walks upto you and says, how do you drive?

You could say, well you jump in the drivers seat turn the key to start the engine and off you go. In its most basic form thats about right, but a non driver couldnt then jump in and do it like that. For example, first before you can accurately give instructions you would need to know few things, for a start what exactly do they want to drive? a car? Van, Lorry? Automatic gears or manual, etc etc.

Bio gas is alot like that, so far most the info has bordered on the jump in the drivers seat turn the key and go. So here I will take you some way down the fascinating rabbit hole of Organic Digestion, note i didnt say anaerobic digestion, this is because there is also aerobic methane digestion systems, then you have mesophiles and Thermophiles etc.

Plus several different metabolic pathways methane can be produced and so on, so i thought some might like some info and background on this. Its a bit like home brewing, everyone knows yeast can take sugar and turn it into ethanol and CO2, but not so many know that not long ago Acetone was commercially made with bacteria, it was/is called the ABE process.

ABE process is Acetone, Butanol and Ethanol. Its a process where a bacterium takes sugars and produces all three at the same time, and this was once how commercial acetone was made. A little slightly inaccurate info here...

and gratuitous slightly wrong diagram

As we go deeper in this thread, please dont waste too much time on google looking up acronyms or word, please feel free to ask what something i have said means. I often forget when writing this stuff that not everyone plays with bio digesters!! So its easy for me to throw things in and not realize normal people with lives know what something means, please remember i am used to discussing this stuff with others who study it.
So isnt stupid to ask what something means, often its simply because i have forgot my target audience, and its something i get picked up on alot at uni presentations etc.

So it also helps me learn to write material aimed at a specific audience (something i am bad at).

So next post we look at who is involved in what (organic digestion wise), how they normally do it and how they can do it, also we will look at the different types of Digestion, from aerobic and which microbe/microbes do it how they do it and the same with anaerobic, then onto the different temperature types, i might also delve into a chicken and egg thing, that actually has an answer.

This is the one where Archaea (the oldest organisms and probably the first things in the soup of life) managed to produce methane when there was nothing to produce Oxygen, if there is nothing to produce Oxygen how can you have CO2? if you cant have CO2 how come there was methane? Reasonably recently this got answered and accepted, as it turns out i was disappointing with the answer, but its still a fun question about the beginnings of life on earth.

AND before i forget......Being a big NOOA fan, congrats to them for the recent discovery of a new thermophilic Archaea they found lst year down the Marianas trench and recently confirmed as new! lives in water close too 185C!!


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Ok i cant finish alot of the threads i started at the moment, but this one is ok, i will just stick to the metabolic processes and some the common well known systems. I wont be able to add in anything of our own research or methods here for now.

But looking at how microbes produce bio gas and bio methane is worth while if you want to have a go at making a system for home. We might get a chance to touch on microbial cells, these are superb as the end process, If we get a chance and dont get trolled i will also give some commonly published pre treatment methods, we dont use them ourselves the way i present them here. The principles however are roughly similar. Its just we do it differently and much more efficiently.


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I tried to find a easy to understand pic of methanogenesis in anaerobic conditions, i found one but please note while it uses a cow in the pic......The pic is actually wrong!! It suggests that most methane is ejected from the back end of a cow, this isnt the case, Cows expel the most methane from there mouth by sort of burping. I might try ad find a reference to back that up! but the processes shown are accurate, just not entirely in the right place in this pic.
So in anaerobic batch systems there are 4 stages

One point to make is cows are not entirely Anaerobic in digestion, For a start the first two stages are actually both Aerobic and anaerobic! :stop:o_O Ok so how can that be!! Surely not?? Well yes.
Actually its no big mystery its just kinda normally forgotten about or ignored (big mistake as its a very important step ;)). Cows chew the cud, this means they chew in aerobic conditions in the mouth, they add enzymes via saliva, they are pretty clever with this. A cow chews until they get a sour taste, at which point the cow swallows the cud into the first stomach chamber.

This first chamber takes the enzyme laden mangle and a vast number of many different microbes set to work on it, some are anaerobic and some are semi aerobic. After a while the cud stops being bitter, this is the point some Acidogenesis has taken place.

Point to note with cows, they swallow into the second chamber then start to chew a fresh batch of grass. At the point the cud has stopped being bitter it is brought back up into the mouth ad a fair bit of methane follows, the methane is from further down the digestive tract, but as your going to see cows are the methane masters!

As they bring up the old cud, the fresh stuff they were chewing passes down into the first chamber! So they kind of pass each other! In many ways this is more like a continuous process than a batch system.
They then start to rechew this partly broken matter some more, adding more enzymes. this back and forth will continue a set number of times depending on the feed ad the feed quality.

I will be back with more info, the delay is simply because its not a quick job to sort the information for the next part.

I am pre writing the next bit, so i can include why some pretreatment is done and at this point i will discuss several of the key player microbes.

Choice of microbe can make a big difference. Yes you can just add some cow ****, but larger professional systems have pure strains of specific bacteria and microbes.

Alot of fine tuning goes into using specific microbes in each chamber, no you dont have to do this. But in the kind of full scale 'industrial set ups', the strain of microbe can make a big difference.

Isolating the various microbes and then culturing and preserving them in a pure state is extremely difficult for some strains, it isnt something your going to be able to do with jam jars and DIY techniques..

The special incubators alone can cost an enormous amount, they even have O2 concentration control. Speacial compartment sealing and HEPA filtration as well as full air make up control. They are know as CO2 incubators, but you dont always use CO2 cylinders.

We currently have 4 of these professional CO2 incubators, One has a completely O2 free environment. Predominately this one uses Nitrogen or Argon as the atmosphere. We also use special 1.3ml sealed vials that go into special 'boxs'.

The boxs seal and hold 109 of these special 1.3ml tubes that contain the cultures.

As a company we collect and culture as many anaerobic strains as we can and asses each of them, we also sell some pure strains and have a kind of depository for different strains that is registered.

For me its one of the single most difficult things we do, isolating and RNA/DNA identifying each pure strain takes time and money, keeping pure cultures going is also very difficult. Some strains are ultra sensitive to Oxygen.

The other thing we do is take plasmids or part of the DNA from the microbe and fuse it into another strain, this technique is more often known as genetic modification.

One area of research we are doing involves taking a common Aerobic organism and altering its DNA to produce methane instead of its normal metabolite. These Organisms are then encapsulated into a harden outer algenate.

We havnt perfected this by a long way yet. But once done it would allow some of the best but most sensitive strains to be handled and used alot me easily.

Its extremely cost and time intensive, but would revolutionize digesters. This is probably one of the single most important reasons i decided to do a part time masters degree, the research would count towards a PhD. Which obviously is something i would like to achieve for my dad.
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As this thread is very much on the technical aspects of microbial metabolism, I think we should first take some time to go through how metabolic processes are driven. From some of the threads i have done, its clear some people really dont understand the process of metabolism,especially in regards toit role in the production of a metabolite or end product.

The first diagram in this thread is a good example, so i will take some time and explain what things like CoA and AD
P/ATP are, and what they do. This area is very much Bio chemistry, it describes exactly what is taking part inside a cell and what affect it has. Known as cellular respiration, you might be surpised to learn that our cells are very similar in Humans, most of our cells contain ATP, CoA etc.

ATP is one of the most important chemical molecules in living cells, It stands for Adenosine Tri Phosphate. Its the main 'fuel' for a cell, once metabolism is understood, it then becomes clear how you can use this to manipulate what a cell produces. For example if you look at yeast metabolism you can start to see how altering the conditions for yeast cell, you influence which pathway the organism uses and in doing so what the metabolic product is likely to be.


Are you suggesting that modelling a system on how a cow breaks down food and generates methane is likely to be the most efficient ... or just drawing parallels.

From some of the threads i have done, its clear some people really dont understand the process of metabolism,especially in regards toit role in the production of a metabolite or end product.
That'd be me ... I have zero clue on how it all works ... but I figure if I could understand it at least a little ... it may help if I do pursue building a bio methane system.


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Are you suggesting that modelling a system on how a cow breaks down food and generates methane is likely to be the most efficient ... or just drawing parallels.

If you keep in mind what i said about cows giving off more methane via the mouth than the rear end, then yes pretty much. Most modern multi chamber systems are models to some extent of a cows 4 stomachs. We dont use the normal model however, because as i said they dont F art the methane, most of it is expelled via respiratory metabolism. So most multi chamber system all have the same issues, what people normally call continuous flow systems are not really.

All those systems do is model the diagram above and continuously fill one end and take out the other. Our gas is take from module 3 and 4 mainly. It isnt the same as what the diagram above has labeled as 3 and 4 however.

This is why i decided we need to look at cellular respiration, take a good look at what goes on at the cell level. That way you start to understand what you need to copy or rather what is required, if you want the best results.

That'd be me ... I have zero clue on how it all works
No far from it, your receptive and clearly go and research what you dont understand. The real trick next is to 'teach', 'show' you what to look for in the literature, the best way to do that is to explore how a cell works and how to manipulate its environment to best effect.

The other reason we dont exactly model a cow is........they dont eat ****, they eat grass, so they are optimized for high cellulose diets. The only time a cow eats **** is the calf when its first born, the mother takes a dump and the calf eats what it can, this self seeds its own digestive tract. These days not calf's can do this because of modern farm practice. But those that have the opportunity will, also most closed indoor herds are not fed grass, they get fed pellets and silage.

But in principle we do use a highly modified cow.


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To explain metabolic pathways and how environment affects them, does anyone mind if i use something like yeast to explain? It will help when i then explain methogens, the reason for picking yeast is they are considered a model organism, also they have a good number of potential paths ways affect by there environment. So it makes showing what you feed something, or the conditions it lives in, easier to follow.

Home brewers will also like it :D.


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Its taken ages to find information easy to understand!! It would take a large book to fully go into cellular respiration, so i propose using yeast to explain the basics however, be aware once we apply it to methogens things change a little, this is alot easier to understand once we start! AAll i am trying to do is enable anybody reading the thread, to be able to grasp the basics of some of the diagrams.

Unfortunately nearly all diagrams of metabolic pathways use a special kind of shorthand and arrows, so it isnt that i am too lazy to track down different ones, it just how its done. PLEASE do ask for clarification on any thing you dont get. Last year i learnt to ride a mono-cycle, it took me 5 months!! Well cellular respiration can be alot like that, it can take a while to understand but once you do, you then wonder why it didnt go straight in!!

Sorry but i have yet to meet anyone who got respiration straight away! Unfortunately it does really matter, and once you get the basics it really does open up another world in many areas. I wasnt going to confess, but it took me nearly 18 months solid study to really understand it, we dont need to go that deep (thankfully) but we do need to take a good look at it.

On the electrical side, understand cellular respiration, and suddenly the potential of microbial cells takes on a whole world of possibilities, no we wont ever power the planet with it, but we can get rid of waste sludge and produce a decent amount of energy, so win win. I have got an email from someone, it challenges me to something to do with microbial cells, now i am unsure just how possible what they ask is. But after we finish this thread, if anyone is up for it we can have a bash at the challenge!! Plenty of electrical trickery in it, and it would be really interesting.

So joule thief and smps guys, your services will be needed! shouldnt take long to do, on a personal level i am really intrigued to see if i could actually achieve whats been asked. I will give info later, but i need the camera first or i got to type reams!

Let me kow during the next few pots if i have the balance of info right. I want it to be as simple as ican make it, but i also want to make sure the principles are covered, so please please do speak out if you dont get it or if i make it too simple. Teaching is not my strong point.


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I havnt given up on this, i chose yeast to do as an example, it turns out that was a bad choice!! I am trying to simplify some drawings or i might look at another microbe to show what i want to get across. I had totally forgotten yeast are kind of special, belonging to the fungi kingdom (sort of) they dont fall exactly one way or the other. So they have 17 possible pathways for both anaerobic and aerobic pathways, but the bit that make them a bad choice is they stop short of the electron transport train.....under all but two circumstances.

All this will make more sense once we get into it, metabolism is one of the hardest bio chem subjects to explain, but once you grasp it everything else slots into place. It isnt that difficult once you know it, its just not easy to explain.


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ya iv been catching up on this stuff too. all about composting cycles. it is funny that in a aerobic system more ferts are produced, in the anerobic system more methane is produced,
have you seen the microbial fuel cells yet?
I hear a roumer that the local university is building one to collect the dog waste in town!
I think google or someone similar bought a system but its like 1000000$

I did math once where i calculated that it was like 8cents of natural gass(to get 1 kwh) and resells at 11cents then you could use a 100000$ generator that can do 100000kwh in to a grid tie.
i think the answer was you double your money every year and generator lasts 10yrs ... but I didnt calculate installation, grid tie and other expenses that i have no idea about , it would be cool if someone could post an actual projection of one of these


ya iv been catching up on this stuff too. all about composting cycles.

I find it very interesting too ... and have been waiting for large_ghostman to come back and update the thread. Maybe he's in the naughty corner. :)

I had a local dairy farmer bring in a spa pump with a crook controller last week ... told me they use it for their microbe growing tanks. First thing I asked him was whether he was into microbial fuel cells ... but no ... they grow microbes in 5000 litre batches then spread it on their pastures.

He certainly believes it works well and is worth the trouble ... has been doing it for over 15 years. Also helps in retaining the farms 'organic' certification.

He'd been quoted a new pump at $1500 ... and it took me 2 minutes to find a replacement controller on google for $650 ... but all I needed to do was replace the tact switch under the air pressure switch and reglue a pad on the actuator ... and I almost felt guilty charging him $120.


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... and have been waiting for large_ghostman to come back and update the thread. Maybe he's in the naughty corner. :)
LG is not currently "in the naughty corner". My understanding is that he simply has a lot going on in his own life at the moment and hasn't been able to visit ETO very often. I'm sure he will return as soon as he can.
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