Talk:Anaerobic digestion

Required article improvements
Hi all. Just a note to for article improvements and requirements for new sections/structure:


 * One-stage and two-stage anaerobic digestion systems
 * High solids and low solid systems
 * Mesophilic and thermophilic systems

--Alex 09:41, 16 August 2007 (UTC)

Mesophilic Digesters usually only require 10 days of residence time vs. the 15-40 days referred to in the article. Requires means, that 10 days is necessary for stable operation and development of the mesophiles. To attain a Class B sludge in the US, 15 days of residence time is required. To attain a Class A sludge, temperatures of the sludge need to be increased to thermophilic levels.

Also, the section talking about the wastewater from the process refererences reverse osmosis(RO). This is misleading as RO is in fact used rarely in a waste water treatment plants and is really only used if the waste water is intended for reuse. The use of RO has nothing to do with an anaerobic digester per se & has a lot to do with the overall operating philosophy of a waste water treatment plant.

--Vogted37 (talk) 03:54, 21 July 2008 (UTC)

Energy output?
The article states that the energy consumption is larger than the energy output from the plant (Last section under the Reactor types heading)I find this very unlikely and contradictory to articles I've read on the subject. For example, in the article "Kompostering eller rötning? En jämförande studie med LCA-metodik" by Nilsson, B. (1997) (this article is refered to in another article thats available online: "Life Cycle Assessments of Energy from Solid Waste" by Finnveden et. al. (2000) ISBN 91-7056-103-6) inventory data was collected at the digestion plant in Kristianstad, Sweden wich shows that the energy content of the methane gas collected from the anaerobic digestion is 3743 MJ/ton food waste, and of that only 495 MJ is used internally at the plant. -- KristoferP 15:02, 5 March 2007 (UTC)


 * Well spotted. Whoever wrote this addition badly worded their intentions. I have deleted this. On most major AD facilities there is a net output of electricity. The operational facility I worked at at Hiriya, Tel Aviv had an energy output 5 times the plants operational requirements.--Alex 16:38, 5 March 2007 (UTC)

Merging Anaerobic Decomposition with Anaerobic Digestion, Biogas Power Plants merger with Anaerobic Digesters and related redirects!
Technically I believe there should be some reworking of this. I have created the Category: Anaerobic digestion as there is a significant number of articles that are linked to this subject. I am in two minds if to merge anaerobic digesters with biogas powerplants and to merge anaerobic digestion with anaerobic decomposition. Anaerobic digesters and biogas power plants are the physical buildings constructed to make use of the process of anaerobic digestion/decomposition.

There is a lot of similarity between anaerobic digestion/anaerobic digesters and biogas powerplants. Technically there is very little difference between the two and I am tempted to suggest a merger of the two articles. --Alex 08:15, 24 July 2006 (UTC)

There is a lot to be added to this, a lot to be corrected and changed, unfortunately I know very little about the subject, but I’m trying to learn. It’s better than what was here on the subject before, which was nothing, but hopefully this will get the ball rolling and if you can correct this, make it better, or add something of value, please do. Renewable energy is an important subject, the more knowledge on the subject that is out there the better.

Sorry if my comments seemed brusque. No criticism was intended - its good to see a useful article taking shape. I have done some editing based mostly on UK sewage treatment and agricultural waste experience. We probably need articles or references for acidogenesis and acetagenesis if these terms are to stay in here. Looks like a good start. Velela 15:34, 26 Feb 2005 (UTC)

I was searching for a Wikipedia article on "anaerobic decomposition" and was redirected to this. It is not at all what I was wanting. I was researching the natural process, in nature, and had no interest in the industrial process. I believe they are distinct enough to warrant separate articles. &quot;Pij&quot; (talk) 23:04, 19 March 2010 (UTC)

Anaerobic Digesters in Hog Farms
I was hoping to read about the potential of anaerobic digesters for hog farms. From what I understand it could serve as an important supplement to natural gas.

-When I get some free time, I will try to add to this article. In particular, I'd like to include some mention of plug-flow (as opposed to completely-mixed) digesters, since they are more efficient and much less expensive to build. Also, I know that New York State offers net-metering (as with PV) for certain biogas digesters, and several dairy farms in the region are able to meet and even surpass their entire energy need through processing of cow manure -- so maybe I'll look into that. Furthermore, there's a tremendous amount of research going on at the college where I go to school (Cornell University) that concerns anaerobic digestion -- not to mention interesting research that has been going on for decades. One of my professors had a project in the '70s that diverted waste flow from the Ithaca municipal waste treatment plant, treated it with anaerobic digestion (plug flow, of course), then used the nutrient-rich effluent in hydroponic production of ornimentals, all very successfully until his funding was revoked by nay-sayers and militant conventionalists. The contrast between my professor's experiment and the conventional approach to waste treatment is stark -- one approach, the brute-force approach, requires large amounts of energy (in addition to steel and concrete), produces nothing of value and sends large amounts of biosolids to the landfill; the other, the ecological approach, instead produces energy, as well as valuable byproducts, and minimizes or even eliminates flow into the landfill -- it even uses less land area...!

I'm taking another class with that same professor this semester, so this kind of stuff is on my mind a lot. At semester's end, I'll probably do some contributing. I'll try to keep my enthusiasm contained.

Could large scale anaerobic digestion reduce natural gas consumption?
If a great deal of money were invested, could large scale implementation of anaerobic digesters be sufficient to reduce America's (and other industrialzed nations') natural gas consumption? Natural gas appears to be causing the same kind of geopolitical problems as petroleum and yet all signs point toward the problem getting worse. Is anaerobic digestion a potential solution? In neither the anaerobic digestion nor the Biogas articles can I find information on how much potential the technologies have for reducing natural gas consumption. If most American cities topped out the anaerobic digestion potential of sewage and other waste matter would their natural gas consumption only go down slightly, or might it drop considerably? Ideally I'd like to see America remain independent of LNG imports, but I have no idea if that's possible with anaerobic digestion.

Yes, by utilising the correct AD technologies that enable the highest concentrations of methane in the biogas it is possible to reduce natural gas consumption. In less pure biogas streams, cleaning or scubbing of the gas may be required. If you are interested in the subject please see the links on my profile or email me. --Alex 07:57, 16 June 2006 (UTC)

It is also worth remembering that managed land-fill can generate substantial quantities of bio-gas over periods of many years. Unfortunately the potential here is not as great as it may seem since a great deal of waste has the carbon locked up in plastics that are difficult or impossible to degrade. This has the overall impact of converting fossil fuels into carbon that is seqestrated in the ground. Velela 14:59, 19 June 2006 (UTC)

Landfill gas is much harder to collect efficiently than fully engineered anaerobic digesters. It also has lower levels of methane and higher levels of siloxanes which are abbrasive to gas engines. Landfill gas escapes much more easily into the atmosphere and is a significant greenhouse gas. There are major benefits to engineered anaerobic digesters over landfill gas capture. --Alex 16:20, 19 June 2006 (UTC)

I don't disagree, but if one is looking at the biggest picture "How can we offset our use of gas from fossil fuel sources" then getting better at maximising the land-fill contribution should feature in the debate. If we managed land-fill differently so as to maximise gas generation, then it would become more economic even if it was only used to fuel district heating or other similar local use. At present very large volumes of methane are vented in an uncontrolled way adding significantly to the greenhouse effect when we could have collected and burnt it to offset our use of primary fossil fuels. It would also be intersting to know the respective calorific values of all the sewage sludge and of all the solid waste and compare them. I suspect that in the UK domestically, more energy in solid waste is thrown away than is discharged to the sewers. Anybody up for the calculation ? Velela 16:29, 19 June 2006 (UTC)

If you look at the present legislation for landfills, the waste management industry is moving towards the minimisation and eventual elimination of biodegradable waste entering into landfill. In the mean time landfill gas must be fully utilised as a green energy source. It is my personal oppinion that anaerobic digestion is ideal for the pretreatment of waste for the controlled production of biogas for utilisation in energy generation (as opposed to random in landfills) and will form a significant basis of waste management in the UK for the future. (this is if the government doesnt have its way with the wide scale introduction of incinerators across the country) --Alex 14:54, 17 July 2006 (UTC)

Dead links
The link to reference 7 ( ^Cruazon, B. (2007) History of anaerobic digestion, web.pdx.edu. Retrieved 17.08.07.) is dead. — Preceding unsigned comment added by 193.191.150.2 (talk) 11:08, 7 November 2011 (UTC)


 * I had no problem with Ref. 7, but some of them are dead, like 12 and 58. Phorious (talk) 19:49, 23 January 2013 (UTC)

Biogas digesters
Biogas digester redirected to Biogas, so I've redirected it here instead.

The question is: does "biogas digester" mean basically the same thing as "anaerobic digester," or is one a subset of the other? (I'm guessing that almost all anaerobic digesters capture the biogas.)

I'm interested in the appropriate technology side of this, and would like to help develop info on biogas digesters used in the developing world or small-scale settings... however, I haven't yet found good sources suitable for an encyclopedic article. Can anyone suggest good sources? -Singkong2005 talk 03:21, 20 September 2006 (UTC)

Hi Singkong, yes a biogas digester is the same as an anaerobic digester.--Alex 08:02, 20 September 2006 (UTC)

Akron, Ohio plant
The U.S. city of Akron, Ohio is planning to build a plant, apparently to be the first ever in the United States. The mayor had been inspired after seeing a plant in Europe. Badagnani 07:04, 22 May 2007 (UTC)

Climate change
I added an unreferenced section tag, my reasoning is as follows: Reduction in global warming? From biogas? I think this is a very strong statement, and I can think of some arguments that would cast doubt upon this. For example the simple reaction given is pretty much the same as complete oxidation of $$C_6H_{12}O_6$$ in the presence of $$O_2$$, so if you are using it as an energy source from this view it is no more a greenhouse reducing device than burning natural gas obtained from a gas well. However if it is using a currently untapped resource that is unconditionally occurring (ie if this chemical is breaking down in the same way anyway) then it *is* alright to make this statement, with qualifications. Without some sources I think the validity of the "Contribution to prevention of climate change" is suspect. I know climate change type topics make people quick to comment, but I think this section needs to be more carefully written. The last thing we need is people who may not be familiar with the topic taking this as an unambiguous absolute. Thanks User A1 16:28, 17 August 2007 (UTC)
 * Wow, that was fast. Better, but still could use a bit of a fiddle. I'm off so I will think and re-examine tomorrow; Thanks guys & girls User A1 16:34, 17 August 2007 (UTC)
 * You had good timing, I have been in the process of improving this article.--Alex 09:37, 19 August 2007 (UTC)


 * "it as an energy source from this view it is no more a greenhouse reducing device than burning natural gas obtained from a gas well"
 * Not correct. When burning mineral methane the C component has come from fossil sources. When burning gas from an anaerobic digester the C component has come from recently grown plant material, so in that sense it is simular to a biofuel.


 * With fossil gas it is CH4 -> CO2
 * With anaerobic gas it is CO2 -> CxHxNxOx -> CH4 -> CO2   So it is a closed loop  —Preceding unsigned comment added by 202.50.184.138 (talk) 20:37, 31 March 2010 (UTC)

GA Review

 * GA review (see here for criteria)

Good overall. This article may be little confusing to those who're not in scientific fields. Please fix these and inform me when you are complete. OhanaUnited   Talk page   22:16, 18 August 2007 (UTC)
 * 1) It is reasonably well written.
 * a (prose): b (MoS):
 * 1) It is factually accurate and verifiable.
 * a (references): b (citations to reliable sources):  c (OR):
 * 1) It is broad in its coverage.
 * a (major aspects): b (focused):
 * 1) It follows the neutral point of view policy.
 * a (fair representation): b (all significant views):
 * 1) It is stable.
 * 2) It contains images, where possible, to illustrate the topic.
 * a (tagged and captioned): b lack of images (does not in itself exclude GA):  c (non-free images have fair use rationales):
 * 1) Overall:
 * a Pass/Fail:
 * a Pass/Fail:
 * "The carbon in biodegradable waste is part of a carbon cycle, as such the carbon released from the combustion of biogas can be thought of as having been removed by plants in the recent past." What does "recent past" mean? State the year or decade.
 * Majority sections are unreferenced, including:
 * Most of "Stages of anaerobic digestion", "Process configuration"
 * Whole section of "Products of anaerobic digestion", "Feedstock considerations", "Consideration of suitability"


 * Further reworking has now been done, I welcome any further comments.--Alex 09:15, 19 August 2007 (UTC)
 * ✅ Looks much better now. I announce that this article passes GA standard.  OhanaUnited    Talk page   13:44, 19 August 2007 (UTC)

Comments from FAC Nomination Withdrawal

 * Comments I enjoyed reading this; it's accessible and I learned much. As science and I are frequently complete strangers, this is a major plus. I have some criticisms. Fun though the assyrian bathwater anecdote might be, isn't there a more substantial source to back it up? And, incidentally, some of the shorter sections are scarcely referenced at all. Finally, WP:MOS isn't keen on superscript for ordinals (e.g. 17th century). -- R OGER D AVIES  TALK 13:14, 24 October 2007 (UTC)
 * Hi Roger, I am pleased that you enjoyed the article. re-Assrian bathwater I am presently consulting with people on the anaerobic digestion forum to find more information and the original source of this. I will look over the shorter sections and find suitable references. Thanks againAlex 13:20, 24 October 2007 (UTC)
 * ✅ I have now significantly added to the references, I have also addressed the dating issues. Finally I deleted the reference for Assyrian biogas, I cannot find a suitable reference anywhere even though there are hundreds of quotes on the web.Alex 14:38, 24 October 2007 (UTC)
 * Thanks. I'll abstain for the moment though as I'd like to see what other editors with a firmer science footing say. -- R OGER D AVIES  TALK 07:24, 25 October 2007 (UTC)


 * Good quality article. In the past there haven't been many clear, thorough articles on water and wastewater but  Alex is changing that. Good work! --Chriswaterguy talk 14:07, 24 October 2007 (UTC)
 * Comment, peer review archived, please note per the instructions at both WP:PR and WP:FAC that the article shouldn't be listed simultaneously at both places. Sandy Georgia  (Talk) 18:08, 24 October 2007 (UTC)
 * Oppose for now I was hoping you weren't going to nominate this for FA yet because it still has lots of work to do, and places that need to be expanded. The article is really starting to take shape, though, it is not stable enough now to be featured, perhaps in a few weeks it will be ready. Anyway, I'll list some more comments:
 * Make sure the content is under the right headings, for example I found the following under "Applications"
 * "After sorting or screening to remove physical contaminants, such as metals and plastics, from the feedstock the material is often shredded, minced, or hydrocrushed[19] to increase the surface area available to microbes in the digesters and hence increase the speed of digestion. The material is then fed into an airtight digester where the anaerobic treatment takes place." This belongs in a different section.

I strongly urge you to withdraw the nom now so you can work on it in peace, for 2-3 weeks or so. Once it's ready then relist here and start with a clean slate. I am willing to work with you on this one, and if I have time I can make some edits to the prose too. Jeff Dahl (Talk • contribs) 19:35, 24 October 2007 (UTC)
 * ✅ and accepted, it was definately not appropriate here.--Alex 08:04, 25 October 2007 (UTC)
 * Image:Anaerobic digesters overhead view.jpg I can see the brown liquid, so point it out in the caption ✅ expanded caption to include mention of process water.
 * Must explain the steps in the process better, say why each step is necessary. For example, the hydrolysis step is necessary to break down the matter so that the bacteria can digest it, right? Tell us more and expand each step.✅
 * "This contrasts to carbon in fossil fuels that has been sequestered in the earth for many thousands of years." You must mean millions of years
 * "can be considered to be sustainable and biogas considered to be a renewable fuel." Some people believe that this can be considered, in some circles, to possibly be a weak way to write a statement.
 * ✅ I have significantly reworded this
 * Emphasize/contrast the end products more clearly between anaerobic and aerobic digestion ✅
 * Emphasize why anaerobic digestion is better than simple aerobic digestion, in that the value of the end products can be used.✅ and moved to different article following comments from Jeff and Valela.
 * Avoid abbreviations like BOD and COD; I would get rid of AD as an abbreviation since you hardly even use it! (nor should you!)
 * Comment ✅ I have removed AD abbreviation and expanded the meanings of BOD and COD as I think they are appropriate.Alex 11:23, 25 October 2007 (UTC)
 * how do siloxanes get into the biogas?
 * ✅ section expanded and clarifiedAlex 12:41, 25 October 2007 (UTC)
 * "landfilled" is this a verb now? 2 places
 * Comment- it is certainly used that was in our industry. Do you think this is incorrect?
 * The lead should mention, in passing at least, that biogas is mostly methane and carbon dioxide. Just a brief mention is all it takes; do it in the lead.
 * "hydrocrushed" what?
 * ✅ Have reworded this marketing type term to hydraulically pulped.Alex 08:04, 25 October 2007 (UTC)
 * "hydrocrushed" what?
 * ✅ Have reworded this marketing type term to hydraulically pulped.Alex 08:04, 25 October 2007 (UTC)
 * Hi Jeff, Happy to withdraw it for now if you think it will be worthwhile. The feedback is appreciated. Would also appreciate your assistance getting it to the final shape for FA.--Alex 07:39, 25 October 2007 (UTC)

Organization
Taking a look at the organization of the article, I would suggest a few changes. I'm not entirely sure how to go on this, so I'll post discussion here. Now unless I'm wildly mistaken, we don't normally use a "background" section on articles, so I would consider moving the History section up to a ==level 2 heading==, move "applications" to level 2 heading at the end and combine "climate change" and "suitability" into it. Consider putting "biochemistry" into a different section, or merge several sections into one. Some of the section headings could be more descriptive; consider changing "complexity" because it is too generic. I think there are too many headings, which is why I (temporarily) forced it not to show the deeper headings. For example, 'hydrogen sulfide' and 'siloxanes' don't really need their own headings; consider just putting them all under the level 3 heading Biogas refinement. I usually only use up to level 3 headings anyway. I'll think it over some more and see if there's a better way to organize it; once it is better organized, it will be much easier to work on. Also, on the image Image:Stages of anaerobic digestion.JPG did you mean Protein->amino acids? Forgive and please fix my American spellings; I probably won't be able to consistently write the British ones. Jeff Dahl (Talk • contribs) 04:01, 27 October 2007 (UTC)


 * Hi Jeff, worked in the above changes, don't have any problems with them. Regarding the image, the protein->protein section is correct (proteins arent affected by the hydrolysis stage). No problems on the american spellings will alter things where appropriate.--Alex 12:09, 30 October 2007 (UTC)


 * Been giving some more thought to the proteins:amino acids issue. I have decided that the original graph was not necessarily quite as close to reality. There is quite a blurred line between what is hydrolysis, acidogenesis and acetogenesis in the literature. Without getting too complicate I have decided that Jeff's comments above are of relevance and incorporated amino acids and fatty acids into the flow chat whilst blurring the strict lines between the 4 stages.Alex 08:41, 2 November 2007 (UTC)

I'm going to try a little re-organization which I think will help focus the article, and I will do a little re-writing to help reduce redundancy. Suggest looking through the refs again for new information. Though we don't want to overload the article with trivia, there are quite a few good sources listed with loads of good content to add. Jeff Dahl (Talk • contribs) 02:59, 3 November 2007 (UTC)


 * Sounds good to me. I have reworded the last paragraph you added on critique of AD. I think it came across as a little too negative. I have altered it to keep it factual and NPOV. Digestion is reliable as long as people operate the systems correctly. Also the monitoring equipment is well developed, it really comes down to ensuring you understand the process and don't put the wrong materials in. I have added more information on seeding the digesters. The article may also require something more on solids content but haven't thought how to tackle this yet. I agree with the above comments, there is a little redundancy and duplication in some sections--Alex Marshall 10:42, 5 November 2007 (UTC)

I took a look at the Aerobic/anaerobic comparison. I actually got this confused with Aerobic/anaerobic respiration, which actually have their own articles. So perhaps we don't need this comparison after all. But probably should mention why anaerobic digestion is not composting. Jeff Dahl (Talk • contribs) 03:17, 6 November 2007 (UTC)


 * Following the comments below from Valela and the above comments I have created a new article Comparison of anaerobic and aerobic digestion which contains elements distinguishing between the two processes. I agree that it didn't really sit well and I wasn't overly happy with it.--Alex Marshall 15:07, 8 November 2007 (UTC)

Applications section layout
The article is clearly getting expanded for the better; all this new material needs to be integrated. In the applications section, for example, we have: And then 3 paragraphs later: I suggest grouping the material into level 3 headings: "Waste treatment", "Renewable energy", "Greenhouse gas reduction" or something along those lines, underneath the level 2 heading "Applications". Jeff Dahl (Talk • contribs) 19:07, 10 November 2007 (UTC)
 * "Anaerobic digestion is particularly suited to wet organic material and is commonly used for effluent and sewage treatment"
 * "Pressure from environmentally-related legislation on solid waste disposal methods in developed countries has increased the application of anaerobic digestion as a process for reducing waste volumes and generating useful by-products"

Anaerobic Lagoon
I'm confused about the anaerobic lagoon. The article doesn't talk about the purpose of the lagoon, so the caption should mention what it's being used for. Also, if it is exposed to the air, probably should explain why it is anaerobic (sludge buried at the bottom has no access to air?). Jeff Dahl (Talk • contribs) 03:21, 6 November 2007 (UTC)
 * Agreed. Also a similar comment was left by Valela on my talk page. I have included mention of anaeorbic lagoons on the single stage system, which in essence is what it is. As you outline it is the stationary water which isolates the oxygen from the system.--Alex Marshall 08:49, 8 November 2007 (UTC)

Comment left on my talk page: Anaerobic digestion
Alex, as requested I have been reviewing the Anaerobic digestion article which is an immense improvement on the stub that I originally started editing. It is a considerable credit to the few main contributors and editors.

However, I do have some reservations and I have made one edit to try and set it better in its wider context. To me anaerobic digestion describes the process that occurs whenever organic material exists in a micro-organism rich anaerobic environment. These processes have been harnessed by man to great benefit in a range of different ways which, incidentally, include cold lagoon digestion which I don't think gets a mention. The article reads very much as a description of the thermophilic industrial process and is very weak on the underlying microbiology and the range of occurrences in natural and semi-natural eco-systems. There is also one section on aerobic digestion which seems out of place here.If I can and will try and apply some more balancing edits and I hope you will let me know if you think I'm barking up the wrong tree. Velela 18:23, 7 November 2007 (UTC)


 * ✅ Lagoons mentioned as an alternative type of digester. Also have expanded and compiled bacterial section under the process. I don't necessarily agree with the indicated bias towards thermophilic systems, I think there is a good description of both. All the pictures are of mesophilic systems as I don't have any of thermos. --Alex Marshall 16:45, 9 November 2007 (UTC)

Anareobic digestion vs Anaerobic digester
An anaerobic digester is an invention, a device. Anareobic digestion is a process, which can be done with an anaerobic digester but also takes place in nature. Yet it redirects here!? That's not right. They are related, sure, and I submit anaerobic digester should probably be a fairly short article, but still. --206.79.158.100 (talk) 22:19, 8 July 2008 (UTC)
 * I see your points, it would be possible to divide this into two articles but I am unsure what the benefits would be. The individual processes of anaerobic decomposition are methanogenesis, acidogenesis, acetogenesis and hydrolysis and do occur naturally. Each are covered by their own sub article. Anaerobic digestion, to me, is the series of processes which are harnessed in an anaerobic digester. --Alex Marshall (talk) 12:20, 10 July 2008 (UTC)

Production of Sour gas?
Do methane digesters produce any significant amount of hydrogen sulfide, enough for the result to be considered a sour gas? DMahalko (talk) 11:44, 3 November 2008 (UTC)

Home furnace capable of burning biogas?
I am trying to determine if any forced-air or boiler furnaces exist, that are capable of burning biogas from digesters as either a primary or secondary fuel. I'm not looking for some huge industrial furnace but rather something scaled down for home or business heating.

A secondary-fuel furnace would be the most useful, fed primarily with a standard fossil fuel like liquid propane or natural gas, and then with additional burners for the biogas. This allows the biogas to offset fossil fuel usage, but allows fallback to the fossil fuel in case the biogas production is insufficient for continuous reliable use.

So far, my searches for a furnace technology like this are coming up empty. DMahalko (talk) 11:56, 3 November 2008 (UTC)

Moved from main page
In its current form the addition reads like an advert for AADS. There seems to be some useful information in it but it is very lengthy and does not read easily. English is US not UK as the article has been written in. Also random capitals such as 'Biogas'. Please discuss.--Alex Marshall (talk) 15:40, 17 November 2008 (UTC)

Recent, patented developments in the anaerobic digestion process, namely the Advanced Anaerobic Digester System (AADS), have resulted in both sequential batch reactors (SBR) and continuous process plug flow designs that are highly automated and are consequently much lower in annual operating costs. These systems are also readily scalable from 50 Animal Unit installations supporting a 25kW engine-generator to Biogas generators supportive of 20 Megawatts or more of equivalent electrical generation, boiler horsepower, or furnace fuel. The application of programmable logic controllers (PLCs), coupled with oversight by a local, reliable and commercially available digital control system (DCS) software application assures high-performance reliability and results. Heuristic algorithms, self-tuning capability, and the ability to perform Data Mining from the collective AADS database will ensure continually improving operations and promote scientific research into anaerobic bacteria populations and their reactions to changing stimuli. The Advanced Anaerobic Digester System (AADS) requires the presence of few full-shift personnel who will typically have high school or trade school level education in addition to specific training in AADS operations. Monitoring of feedstock receiving and post-process Biosolids and Bioliquids handling will be the responsibilities most often addressed. All process parameters and system equipment conditions are constantly monitored in real time by the AADS control system. Non-nominal conditions or events will be subsequently annunciated or alarmed both locally and to the remote AADS data center. Careful control of the digestion temperature, pH, and loading rates is crucial to obtaining efficient breakdown of the material, and disturbances to a digester can lead to process failure. Ensuring that the quality of input materials to the digesters is maintained and that the process effectively monitored is essential for ensuring that a digester's performance is reliable. The advent of the AADS process makes these tasks much easier for the owner-operator. The new AADS process mechanically and electronically duplicates the digestive processes of a mature Holstein dairy cow, one of Earth's most prolific Methane producers. Effective contaminant removal at the system's front end assures that the multiple-source feedstocks are suitable for Brew preparation. The prepared Brew, prior to injection, and the contents of all SBR or plug flow digester cells are maintained at a constant 101 degrees F. This assures that the process, like a dairy cow, remains healthy at all times. Blending-in or blending-out of multiple feedstocks, based on their changing availability, is directed by menus and recipes within the DCS system. This eliminates operator error and substantially increases the variety of feedstocks that can be processed. I.e.; Natural disasters often produce large amounts of ruined crops and municipal solid wastes that can be readily processed by AADS digesters - in addition to their standard diet of animal wastes, agribusiness sludge, meat processing wastes, Ethanol plant thin stillage, Switchgrass, prairie grasses or other resources. More information on this process can be obtained at http://www.biogasusa.com

Another matter very successfully addressed by the AADS system design is Biogas storage - without added special equipment. A double-cover system is employed on the in-ground plug flow digester cells. This accomplishes a number of goals. The outer cover, pressurized with low-oxygen exhaust from an engine-generator or boiler, etc., provides a durable and intrinsically safe, warm gas shell over the flexible, inner Biogas collection cover and digester cell itself. The constantly pressurized outer cover is essentially taught and tornado proof. Snow, sleet and ice is promptly melted off of the outer cover due to its warmth. Consequently, the inner digester cover is never directly exposed to wind or sunlight, which extends its useful life considerably. The flexible inner cover is allowed to rise and fall based on the rates of Biogas production and Biogas fuel demand. This provides up to 48 hours of Biogas storage per cell should
 * Agreed that it reads like an advertisement. It has been put back in to the main page, and I am again removing it.Withlyn (talk) 04:24, 29 November 2008 (UTC)

Discussion of anaerobic organisms & metabolism
I changed several uses of the word "bacteria" to "microbe" or "microorganism" because methanogens are archaea, and archaea are not bacteria. I still think the section on metabolism is misleading. It is true that all organisms, including anaerobes, incorporate oxygen in their biomass, and thus need it to grow. However, oxygen (the element) is so common in all biological substrates that its presence can be taken for granted. What is really necessary is oxidizing power, which, true to the name, is often provided by an oxygen-containing compound such as elemental oxygen, sulfate, nitrate, or carbon dioxide, but can also come from oxidized metals or sulfur. However, the distinction may be too technical for the average reader of this article. I'd like to see it rewritten to be technically correct but still accessible, but I don't have the time to do it right now, since I have school papers to write.Withlyn (talk) 05:31, 29 November 2008 (UTC)
 * Agreed methanogens are Archaea not bacteria. Happy to support any reworking of chemistry section, but as you say it needs to remain easily readable. --Alex Marshall (talk) 15:01, 19 December 2008 (UTC)

Hydrogen content in biogas
I'm unaware of any bacteria or other microorganism that can produce hydrogen; methane and various sulphides, sure, carbon dioxide and even nitrogen, yep, but hydrogen? Can anybody help here? MrCleanOut (talk) 08:35, 11 December 2010 (UTC)

Hydrogen is always produced in anaerobic digestion, but rarely shows up in the biogas because it is used biologically in so many ways. (Likewise, methane is produced by aerobic digestion, but generally fails to show up in off-gases from, say, compost piles.) Use Google and search for "biohydrogen". Many refs will show up. The basic take-away is that as the pH drops and the process becomes acidic, more hydrogen is expressed in the biogas. However, the economics/energetics have not been shown to be good: producing hydrogen almost always suppresses methane production, and the amount of energy realized in the hydrogen is modest. (David William House, author, The Complete Biogas Handbook) — Preceding unsigned comment added by Mirgy (talk • contribs) 16:27, 30 March 2015 (UTC)


 * Halanaerobium hydrogeninformans maybe ? Mion (talk) 22:02, 1 April 2015 (UTC)

Cost and complexity dispute
The sentence in the lede The technical expertise required to maintain industrial-scale anaerobic digesters, coupled with high capital costs and low process efficiencies, has so far been a limiting factor in its deployment as a waste treatment technology seems either based on outdated information or is just plain wrong. The wastewater treatment facility where I worked for several years employed anaerobic digesters and it was not particularly difficult or expensive to operate them. In fact it was cheaper than aerobic digesters because those require high-capacity blowers powered by large electric motors to run at all times. The system was a very old one that had been in operation since the 1950s. In fact, they simply gathered and burned off the methane on a stack, which always seemed very wasteful to me. The Garbage Skow (talk) 01:18, 10 February 2012 (UTC)

Dry digester: processes
Mention some processes of dry digesters, ie For example, there is the Wiessmann-Bioferm "Kompoferm" process. There is also the Dranco process as designed by OWS, aswell as a system by Jan Klein Hesselink.

Wastewater: mention the thermal hydrolysis process. It seems to be the only economically viable method now in use in wastewater plants. 91.182.142.202 (talk) 09:24, 1 October 2012 (UTC)

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Expanding History Section
I plan to use the below articles to write about when and where anaerobic digestion was first studied, how the technology and processes have changed, and the problems it was developed to fix.

Heukelekian, H. "Decomposition of Cellulose." Ind. Eng. Chem., 1927, 19 (8), pp 928–930. .

Buhr, H.O.; Andrews, J.F. "The thermophilic anaerobic digestion process." Pergamon Press 1977. Water Research, vol 11, pp 129-143. .

Scharer J.M., Moo-young M. (1979) Methane generation by anaerobic digestion of cellulose-containing wastes. In: Advances in Biochemical Engineering, Volume 11. Advances in Biochemical Engineering, vol 11. Springer, Berlin, Heidelberg. .

Stander, G.J. "Effluents from Fermentation Industries Part IV (1). A New Method for increasing and maintaining Efficiency in the Anaerobic Digestion of Fermentation Effluents." Public Health, 1950, vol 14, no 9, pp 263-273. .

Any input on these sources? — Preceding unsigned comment added by Amancalada (talk • contribs) 02:43, 5 April 2018 (UTC)


 * This will be a very challenging task User:Amancalada. You might be better of reviewing current textbooks on this topic as they have likely already done the hard slog to review all the old literature. EMsmile (talk) 03:21, 20 April 2018 (UTC)