Methane Production - Science topic

Victor S Garcia-Rea. Thank you very much

You mean getting water through electrolysis, which decomposes into oxygen and hydrogen. After that, hydrogen is mixed in the presence of a catalyst with carbon dioxide to produce methane.

Biomethane

Just like natural gas, biomethane releases some carbon dioxide and other greenhouse gases into the atmosphere. But these would be released anyway if the organic matter that is used for biomethane production would simply be left to decompose.

Dear colleague

please check:

Regards,

Redimio

Faraed Salman THankyou for sharing both the links and I personally read the shared articles and publications and the second one is quite interesting which shows the environmental impact of the dairy industry which is yes connected to the question raised by me and this is in the circular economy and the part of the question, thank you for your time and the publications you had shared.

Abdul Hakim Hatta, you can read the thermodynamic aspects of methanation in the attached paper

"Life cycle assesment (LCA)" could be jointly addressed with the "circular economy (CE)" and the "ecosystem service valuation (ESV)", as an integrated tool to "quantify the resource-based benefits due to carbon based methane (CH4) production". Besides, this integrated approach can better control the excessive use of material, lowering the energy needs for new products, saving natural sources from overexploitation and environmental degradation, managing labour's capital, and proving the resource efficacy of carbon capture.

Standard enzyme unit is amount of enzyme required to produce 1micromole product per minute.under optimum conditions of reaction

Calculate the product formed in micro moles per minute for a particular volume first and convert it to enzyme units . Then Calculate the amount of protein in the enzyme volume used for assay in mg.

Enzyme unit per mg protein can be calculated .

This is specific enzyme activity.

The international enzyme unit is Katal.

here is the final story i generated.

You can check this study: Mao, S. Y., Huo, W. J., Zhu, W. Y. (2016). Microbiome–metabolome analysis reveals

unhealthy alterations in the composition and metabolism of ruminal microbiota with

increasing dietary grain in a goat model. Environmental Microbiology, 18(2), 525-541.

According to a United Nations report published on August 9, 2021, acceleration of greenhouse gases, including carbon dioxide and methane, is being caused by humans: "Global climate change is accelerating and human-caused emissions of greenhouse gases are the overwhelming cause, according to a landmark report released Monday by the United Nations. There is still time to avoid catastrophic warming this century, but only if countries around the world stop burning fossil fuels as quickly as possible, the authors warn."

Read more at this link: https://www.npr.org/2021/08/09/1025898341/major-report-warns-climate-change-is-accelerating-and-humans-must-cut-emissions-

Biogas recovery for sustainable ciities the critical review shared by Mariana Cardoso Chrispim is really good and am sure that might be of some help to you Dr Mohammad Javad Bardi and yes as I said it depends on personal basis and have loads of 20+ years of exp and yes I can share on individual basis whenever we can and would like to exchange ideas

+91 8317585217 (whatsapp)

The below links shall gie you an idea about measuring methane emissions

Thanks and regards

Srinivas Kasulla

Experts have already answered the question However,

Ni addition stimulates the methane content of biogas, while excessive addition of Ni causes inhibition of methanogenesis.

Thanks and regards

Srinivas Kasulla

Maybe you could share your data with responders. Then it is much easier to help. I am also curious why you want to use the Richads' function and not another.

Yes, it is a bit complicated, since the 'locations' of methane production is governed both by depth and type of soil and oxygen distribution therein, as well as distance of penetration of available oxygen. In a simplified surface-to-soil depth description of methanogenesis, the location of methanogens is typically away from the surface according to decreasing O2 levels and the availability of organic substances (acids) at the location of the methanogenic bacteria. In terms of simplified stacking, if you have a supply of organic acids generated form say fermentation of plant and animal wastes in an upper soil layer (at the bottom of ponds and in the upper layers of organic wastes, leakage flows of these acids through soil layers can be into deeper soils (ponds, lakes, rivers) or soil pockets where O2 levels is reduced (drainage through landfills and waste piles) allows for passage of the organic acids through successive soil or wastes bacteria groups with associative forms of the "fermentation products, such that the organic acids reaching the methane producers (methanogenic bacteria) are essentially the last step for consumption of the the acid products, the product of which is the methane. simply described, the depth of methane production is essential the distance between the point of organic acids production by the aerobic bacteria, to to the distance where methanogenic bacteria can thrive. You can easily see that the space or distance is not necessarily linear, but more likely location specific: with distance variable according to O2 level and availability of organic acids to methanogens. In deeper land soils or soil beds in (fresh) waters, methane generation depends on amounts of organic acids reaching soil (or mud) depths with lower O2 levels. In landfills the methanogens would like be away from the top soils, and/or in soil pockets away from but alongside drainage 'pores' inside a landfill: this is typically layers or pockets of mixed wastes covered by layers of soils for regulatory control of disease and nuisances; but are likely better generators of methane (CH4) within a limited area due to more even distribution of internal pores between layers of degrading mixed wastes: with more even distribution of drainage pores. This would be advantageous for the distribution organic acids from mixed wastes layer, and also the reduction of O2 levels with depth inside the landfill. As the methanogens attach to pockets in soils their locations and mass inside landfills would be subject to the distance from and seepage of degraded organic acids into low oxygen portions of the landfill. This jut suggests that depth, in terms of methane production is more governed by access to organic substances rather than soil thickness; and degree of O2 reduction,

I agree with Mohammed. In addition, sustainable H2 and CH4 (from renewables) can be stored in the Natural Gas Pipeline network and underground for seasonal balancing of Electricity Demand and Supply. Sustainable H2 and methane can also power heavy duty fuel cell vehicles year-round. When wildfires and other natural disasters crash the grid, or lead to rolling preventive blackouts, the redundancy and security of the underground natural gas pipeline network and storage fields can provide stable energy supplies to distributed fuel cells.

Biological methanlization is taking place under anaerobic condition using microbes . So you can not mix with catalytic methanization as bacteria requires different environment for survival.

It is a complete cycle for sure, but specifically about ECBM technology it doest seem a very clear improvement. Maybe someone could help better if read my text, but it is missing some good references. IPCC didn't give the information I need:

Ihab Alfadhel and Shivam Kumar Sharma

" Negative CO2 balance

Another point of attention that may question the ECBM conception is whether, with the use of the technology, there would be actually a negative balance of CO2 in the atmosphere. The main economic objective of any CBM or ECBM project is the recovery of CH4. By producing more methane (CH4), this when burnt will emit more CO2 into the atmosphere, which is the exact opposite of the environmental goal.

It is estimated that burning 1 ton of CH4 can produce 2.27 tons of CO2, while burn 1 ton of C (the major constituent of coal) can produce 3.67 tons of CO2. In addition, new modern electric generator technologies transform 60% of the thermal energy produced into electricity while more efficient supercritical coal-fired power plants operate with 43% efficiency. Thus, the net result considering the same energy production, the carbon burned from coal produces 2.8 times more carbon dioxide than the methane burned. Although it is an important greenhouse gas, the methane is considered the “cleanest burning fossil fuel”. When compared with other types of hydrocarbon fuel, the combustion of methane is characterised by the release of less carbon dioxide and more heat (I don’t have serious reference about that – Richard Muller).

Ottiger et al. (2006) and Hansen et al. (2017) suggested that if all recovered CH4 were burned, there would be net storage of CO2, based on the CO2 balance and cycle. There would be a potential for a net reduction of greenhouse effect gas emissions from this storage option. The balance based on these calculations would still keep the technology as a CO2 negative emission solution.

Sampath et al. (2017) report that methane is the fuel that emits the least amount of CO2 per unit of energy released. The Global CCS Institute 2018 also refers to the environmental benefits through the burning of methane (considered by them the cleanest of fossil fuels) to meet energy demand, and not through the burning of carbon-rich fuels such as coal.

According to Sloss (2015), ECBM projects can be carried out before coal mining, sometimes as part of site safety requirements and sometimes as a means of harnessing this gaseous energy before moving to traditional coal mining methods.

CH4 is a powerful greenhouse gas in which its release should be avoided. However, according to Sloss (2015), at ECBM this gas would be collected under control. This would enable a global reduction in greenhouse gas emissions, together with an improvement in mine safety (US EPA 2015).

This is certainly one of the most important points of attention in the conception of the ECBM project in order not to generate an environmental contradiction."

Hi,

Sabatier reaction is a catalytic method for conversion of CO2 to CH4 by the definition. A very wide catalytic system is available to operate this transformation. A review of the materials and their performances has been presented together with some industrial applications in the following link.

However, if you mean catalyst-free conversion of CO2 to methane gas, as far as I know, there is no feasible method for that and if there is any, it would probably need very high temperatures.

The Italian norm on BMP test (UNI/TS 11703:2018) states that the inoculum/substrate ratio must be comprised between 2 and 3 for general biomass digestion (i.e. 0.5 to 0.33 if you define as substrate/inoculum). Nevertheless, it also states that some substrates (glycerol, fats, industrial effluents containing inhibitors like olive mill wastewater, etc.) may require teh test to be performmed with I/S >= 5. This must be established by the lab operator and stated in the report of the test. For a discussion on the pros and cons of the Italian , German and IWA draft on BMP assay, please see chapter 6 of my book https://www.crcpress.com/Managing-Biogas-Plants-A-Practical-Guide/Rosato/p/book/9781138626614

I think Dr. Sodhi has described it: its more of a rate of transfer of wastewater nutrients from and to specific processes: aerobic digestion unit wastewater nutrients (in oxic sludge) to the anaerobic organisms in the biogas production unit. The oxic-settling sludge to the anaerobic unit/process transports nutrients ("food" or carbon), at rate and thereby richness, between oxic and anaerobic processes. Oxic settling sludge richness is likely representative of levels of food substances entering the oxic unit, therefore controlled by influent substance levels. If richness or "food" value into the oxic unit determines value and rate of biodegradable matter from the oxic unit into the anaerobic process, this should roughly determine biogas expectations: "oxic" sludges are know to contain organisms, their products, and remnants of organic materials not yet hydrolyzed (living and dead organism mass, bacterial slimes, and undissolved oxic unit particulates) - and anaerobic organisms in such settings can use carbonaceous "foods" at rates supplied and according ot species mass development: so it should be that the 'richer' the oxic settler sludge nutrients into the biogas unit, the better the biogas digester gas rates.

To answer this, a physical and chemical analysis of input feed is required. However, I suggest you to examine the chlorine content of your input material, as it is a strong prohibitory element in bacterial activities usually significantly declining the methane production rate.

Manford Malemia thank you for your answer, our company is looking towards the atmosphere

Hi Xiaobo Guo,

An interesting topic. It it would be better if the redox potential of each phase of the anerobic process can be measured, and ensured during the operation. To be more concrete, in anerobic digestion of waste materials, there are anerobic bacteria that contain tetrapyrole compoun containing Ni, Co, Fe etc. and and enzymes that require these type of minereals. There is also report that the concentration of these vital minerals in the environment, can direct and dictate key anaerobic bacteria probably by changing the flow of electrons (or redox potential) that influence the process performance. This maight also happen in animals digestion system. Good luck.

https://www.pnas.org/content/115/27/6970

To obtain reliable answer to your question you should put a detailed description of your laboratory biogas production set up (the design of a laboratory apparatus). I agree with @Abhijeet Singh´s answer above.RegardsVit

The thing is that MRI is basically used for imaging of free water in the system. As it is bonded in gas hydrate crystals, the signal is diminished at theses locations that can be used to estimate the volume fraction of gas hydrates. The method does suck greatly in therms of the spatial and temporal resolution though. There are some papers using this method but they did not provide much of new information. The nicest was the series of papers from a Norwegian group concerning the CO2 exchange on methane hydrate

X-ray tomography can deliver even several hundreds of nm voxel resolution. On the other hand X-ray absorption tomography is not very sensitive to water. Actually it is very poorly dealing with it and at higher energies, the electron density contrast is so weak that distinguishing between gas hydrate and water and gas is very difficult. One needs to spike water with some ions like AgI. Otherwise games in this playground one needs to go for X-ray phase shift tomography that is somewhat limited in the resolution but the contrast increase between phases is just unbeatable.

X-ray tomography is discussed in many papers, far too many to list.

I am very sorry Indrajith Udaya Kumara, but there does not exist answer to your question. The quality depends on many factors (how long the sludge is stored in septics, whar are the sorces of sludge and many more), so the only way, how to find correct answer is to perform monitoring and laboratory tests at first.

Best regards

Vit

Good question...

Hi Jiayi! I can not help you because it's not my subject field

Here is an example of a membrane separator available commercially:

Dear Susi,

I just read your question.I didn't really understand what is your aim. However, commercially there are different solutions for gas production with rumen inoculum, systems that allow you to collect the gas produced during an in vitro fermentation and therefore analyze it for methane concentration. They might be too expensive, so in alternative I can suggest the Hohenheim gas test. It is a very simple method and not expensive. If you need more information let me know.

Federico

thanks

I think not, as the heads were going wrong all the time. I am in the other lab now.

Thanks

I think thats is better to canulate the cows. To use a fettening cow problabily will change the dry matter intake, and consequentilly, the methane production.

Please have a look at this useful ResearchGate link.

Reactor costs

Data on the costs of reactors is scarce as they are commercially sensitive. Assentoft published costs for a 4 000 m3 steel reactor ( height 17 m and diameter 17 m) and Stekelenburg for steel thermal storage tanks with an height over diameter ratio of around one [30;31]

Assentoft published also costs for a concrete reactor 4 000 m3 height of 5 m and diameter of 32 m. Data on a 500 m3 reactor ( 6 m height and 10 m diameter) have been given by Kasper and Peters [32]. Barnaš gave the value for a 3 000 m3 (11m height 11m and 18 m diameter) [33].

Their data can be combined into a model using a power equation of the volume of the reactor.


P = P0 * (V)p [equation 4]

Where:

P is the price

P0 = 1 760 € is the adjusted price for one cubic meter for steel reactors

P0 = 485 € is the adjusted price for one cubic meter for concrete reactors with membrane roof

V is the volume in m3

p = 0.67 is the exponent for steel reactors

p = 0.80 is the exponent for concrete reactors

The equation is reasonably accurate in the range of 350 - 4 000 m3. Only the value of 120 m3 is

35 % too low.

Dear Junaid,

Please read these papers

P is predicted cumulative methane yield, first u will use P (your experimental cumulative value for the computation of lag phase and methane production rate, after getting these two values, u can get predicted methane yield from modified Gompertz model.

I also have fitted three kinetics models on my biogas production values

I found a paper in researchgate in this field:

Coupling of a 3 Phase Methanation Reactor and a High Temperature Electrolyser using Matlab Simulink

Also authors are in researchgate. You can message them

Dear Aleksander,

I did a PhD on the ethylene production of Phaseolus Vulgaris L. and Marchantia Polymorpha L.

With the technique I used, I could measure methane, ethylene, ethane and propane as low molecular weight hydrocarbons at the sub-ppb level using a cryogenic pre-concentration technique. The plants were monitored in an open flow system, with very low backgrounds of the chemical species mentioned. The only hydrocarbon which was measurable with this system is ethylene, no methane, ethane or propane which were below the detection level of the measuring system (0.01 ppbv). It should be mentioned that I always removed the soil when I measured the plants in this system whereby the plants were watered with a glassfiber sheet substrate. If the soil was not removed some other of the hydrocarbons popped up above their detection limits.

It is my conviction that a large majority of plants do not emit methane, but when the soils wherein they grow are measured along with the plants growing on them, methane is bound to be measured as well.

Hence, methane is emitted by soils and not by the plants growing in these soils. Only the separate measurement of soil and plant has corroborated this finding, as I did in my PhD.

Hence, the measuring method has to be critically evaluated on the presence of soil in the measurement protocol or not!

Best regards,

Frank

Hi,

I answered a similar question earlier - here the gist of it:

The main objective when publishing is to be read - as in read by those who are your friends and colleagues in your scientific field. But if you publish in a predatory journal or any other journal that is lax regarding the reviewing process (which essentially means that the editors don't read it at all!), then you will be sorry that you took that route. Why?

It's an easy answer to that question: if the time taken for the journal to come to a conclusion regarding whether your paper needs to be adjusted or can be published is in the order of a week or up to a month only, then you are trying to publish in the wrong journal.

What you need is that the reviewing process is thorough - done by experts in the field. If you submit to any "quick" journal, there is a very high probability that it will never by read carefully by anyone. Why would you risk that to happen? The point is to publish a good paper in a good journal that is read by many - which means that it should be a journal with a good reputation.

What makes you think that you can get a thorough review in a couple of weeks from a credible journal? You will not. Mark my word.

Hi Muhammad, if you read up on syntrophy you can easily undersrand the concept behind Direct Interspecies Electeon Transfer (DIET). Classically, syntrophic electron carriers were though to be small molecules such as formate or hydrogen. Recent models of electron transport in AD systems have proposed a more direct means of electron transport such as direct cell-cell contact through conductive appendages and iron oxides have been suggested to play a role too. It' a pretty intereting process and as well as biogas production and AD, similar processes occur in microbial metal reduction.

I bit disagree with the opinion of Dr. Palangi, methane production in the rumen usually depends on digestibility of a particular feeds. Hay normally prepared from leguminous grasses and silage prepared from non-legumes grasses. according basic rule of ruminants nutrition , if the cattle fed good quality feed staff usually emit less methane  compared high fibre based feed whether may be hay and/or silage.  So, author can go through many review works published by many researchers all over world for consultation, e.g. American Journal of Dairy Science, Journal of Animal Science, AJAS and many others like Canadian Journal of Animal sciences.  

Dietary Possibilities to Mitigate Rumen Methane and Ammonia Production

Efficiency of ruminal metabolism is a significant factor affecting production and release of pollutants, i.e. methane and ammonia. Efficient and balanced ruminal fermentation reduces the emission of gases, particularly methane, to the atmosphere. Losses of energy from the feed ration, connected with the production of methane, are particularly significant in ruminants, since approx. 2/3 production costs are generated by feeds (including forages), fed to animals. Actions aiming at a limitation of methanogenesis in ruminants, at the simultaneous monitoring of quantitative and qualitative changes in methanogens, are justified from the scientific and economic point of view. Proposals of legislative changes include the intention expressed by the European Commission to introduce the so-called cow tax, a tax on kept ruminants. PDF enclosed for further reading

Thank you for your responses. There has been ongoing debate in New Zealand about how long we can continue to improve our per cow production in pastoral agriculture. We have had a steady 2 percent per annum improvement in methane emissions per kg of milk over the last 25 years. Many in NZ argue that we might be reaching a plateau. I have argued that based on the potential of EU and US animals we have a long way to go before we reach any plateau. 

Biogas consists principally of methane and carbon dioxide but can also contain small amounts of a wide range of other compounds. Some of them don’t contribute to the energy content, and may be corrosive, poisonous or be responsive for releasing bad smells in the neighbourhood or during the process. Knowledge about biogas content is thus valuable.

In natural gas applications, a gas chromatograph provides an accurate and consistent method of monitoring the composition of the gas. Gas chromatography involves a sample being injected and vaporized onto the head of a chromatographic column to separate the components of a complex sample. When the sample enters through the injection port, it flows through the column with an inert, mobile gas called the carrier gas. Depending on the chemical and physical properties of the constituents of the sample and their interaction with the particular column filling, the constituents will pass in the carrier gas stream at different rates. The column contains a liquid stationary phase which is adsorbed onto the surface of an inert solid, causing the constituents to exit the column at different times.

For more detail please find attached herewith article.

Tell me if I am wrong.  Anaerobic digestion is essentially a self-limiting process.  In AD the microbes grow and give off carbon dioxide and methane.  However, in this process the natural life cycle comes into play.  Microbes begin to die.  In the decomposition of these microbes, ammonia and hydrogen sulfide are released.  These are toxic to the new microbes.  Eventually, the process reaches its limit.  Work needs to be done on how to remove the dead microbes from the process so that it can utilize all the biomass available to it.

Dear Azarnoosh

As you mentioned, Oxygen is an inhibitor for hydrogen production using C. Reinhardtii; So you cannot use Air diluted CO₂. If you want to use CO₂ as carbon source you have to use N₂/CO₂ mixed gas. I think there must be some mutant strains which are not sensitive to oxygen. In fact oxygen inhibits the hydrogenase activity and as a result hydrogen production will be ceased.

About the time and rate of CO₂ purging, first you have to cultivate your microorganism in a serum bottle and then you can determine the required time.

Interesting question, though this is not my area of expertise, but amount of methane production by lactating cows depends upon nature of feed. Most of the studies reveal during first four lactating periods, methane production is maximum, thereafter it declines. Methane production per unit milk is also dependent upon the digestibility of feed .

Dear Tina,

Thank you for reply. I agree with your suggestion that Thiobacillus denitrificans have genetic machinery to mediate complete denitrification, reducing nitrate upto dinitrogen gas. We are now able to verify this with the nosZ transcript assay as well. Thank you again for your kind reply and suggestions. Best regards, Kumar

Not my field but CSIRO in Australia has spent a lot of effort attempting to decrease methane emissions from rumenants.  I do't know their approach but it's worth checking  

Maybe you can find it. But from my prospective you have to select the environment. Usually the straw rice is contaminated by many species, and it doesn't exclude any interactions between microbes. If this kind of interaction are so strong it will be very hard to find any traces of mono aerobic digestions, because other bacteria could use this product to make new compounds.

After this observation, I think that could be very helpful to check the microbes on the rice and after that check with different cultures if they can makes any mono-anaerobic digestion products.

General answer is impossible. Optimum mixing depends upon geometry of an anaerobic digestor and on other technical parameters.

Regards   Vit

We can send you a cheap powder of nanoparticles, which enhances the decomposition to methane. Write an official letter asking our rector.  All the addresses on the site of our university.

Best regards.

I think it will work according to our previous studies.

Ken, this hopefully  will be answered by the ExoMars TGO mission.

In anaerobic fermentation the end product is methane which can be captured for cooking heating and electrical generation. Anaerobic is a condition where oxygen is very limited. In anaerobic fermentation the condition is maintained in a closed container with lots of solid saturating a slurry. Methane as such can be renewal resource from sanitary waste and manures for example.

In aerobid fermentation the end product is carbon dioxide rather than methane.  The aerobic condition is maintained in composting by turning piles of materials which have enough coarse material that they can aerate. 

Anaerobic fermentation by products can have issues with residue toxic materials. In stabilized aerobic composting these issues are taken care of by the composting process. The residues of anaerobic fermentation would be destined for aerobic composting to make them ready of amendment use for plant productions. 

Maintaining of aerobic conditions in composting prevent the anaerobic products which can be harmful for plant growth and generate foul smells not appreciated by residents surrounding the facilties.  Turning of compost piles allows the maintainence of aerobic conditions as well as combining proper ratios of C and N and materials which have the right textures for aeration. 

A simple test for maturity of aerobic compost is the saturation of test material with water and sealing it in a ziplock plastic bag if after 2 days the material generates no foul smell the compost is stabilized and ready for plant use. This simple test is called the stink bag test. Generally anything that smells bad is not good for crop or plant amendment. 

Raw manures can have issues related to their direct use with the right composting or anaerobic fermentation and composting waste with some noxious nature are transformed into valuable inputs and their issues with disposal are greatly minimized by the 80 to 90% consumption of the organic materials. This is criitical for our soil fertility and environmental issues related to synthetic nitrogen and use of raw manures which can contaminate our water systems through the eutrophication which results from excess soluble products in the water which ends in robs water of oxygen needed for fishery health and best recreational use. 

Dear Hammad,

I can recommend the following publications hopefully answering your questions:

They use Pseudomonas putida strains and K₃Fe(CN)₆ was the most promising redox mediator.

Best,

Michael

Try tritiated water as tracer, easy detection and sensitive (potential on line) detection possible 

I am not sure of the hydrology of the location you collected the samples from, but the CO2 may also be due to the dissolution of carbonates. If the water you are adding is acidic (which probably is), and the location you collected the material from was alkaline, the CO2 may be coming from carbonates.

We are using a system with infrared and electrochemical sensors in our lab from the company awite (http://www.awite.com/products/gas-analysis/principle-of-measurement.html). But there are many other companies out there, e.g. http://www.bluesens.com/english/products/biogasanalysis/laboratoryscale.html

Also, always remember to note down the temperature and pressure in your lab to be able to normalize the gas amounts.

I have only worked with bacteria in the past, but limited.  So I do not know your subject exactly, but generally as a scientist, you run risk if deviating from standard methods.  If your stock inoculum declines in intensity with time, or having increased opportunity for contamination, what  is the result?  Another option would be to increase the number of people doing a month's worth of work in a week.  If you do as planned, you may want to do a standard test throughout as a control, and if results decline too much, consider inoculating with more or make other compensation.  In your results, you should include in the methods the variances from standard methods and how this was compensated for or controlled.  It would be good to discuss this with your professor,, co-author or mentor in the technical field.  

As far as I understand, a depth integrated value for a soil profile is not the mean but rather a 'weighted average' of different horizons. I.e. the thickness of the different horizons expressed as a fraction of the total profile depth is used to calculate the depth integrated value - hope it makes sense

Dear Ciara,

To my knowledge, without any experience in culturing pure hydrogenotrophic methanogen, formate can be cleaved into hydrogen, therefore, you can use formate if you worry about the low soluble of hydrogen. CO2 is easier to become bicarbonate or carbonate, that's not thing need to be worried. I have some experience in running reactor to stimulate the growth of hydorgenotrophic methanogens with applied voltage that produce hydrogen/electron. If you get interested in this, you can check my publication. I think use electrochemical method to feed bacteria can be a novel idea.

Good luck with you and your experiment. 

The question actually have a very simple answer, but one, many people ignore or do not realize: when it comes to metabolic activity, it is veru important to understand tne border of the main catabolic reactions, such as in methanogenic archae and marginal conversions, such as anabolic reactions or side (unspecific) processes. When it comes to biomethane (bio means that it is not thermogenic methane), the only real source are methanogens. No other organisms have the mcr catalyzing the final stage of the methyl group conversion into CH4. There are some evidences that tiny amounts of methane could be releazed as unspecific products from nitrogenase and in clostridia. In you particular case most probably methanogens were present in low numbers but you missed them, which often happen when 16S-rRNA gene is used as a marker. Therefore you must use the methogens-specific functional gene marker - mcrA

Please check these pdf attachment also.

Hi

What is the volume of the digester?

What are the objective of the project? Are you doing a research? Besides cow dung, do you have any other substrate?

The reason for those questions is mainly that, if you are doing research, you can always have cow dung as the inoculum but could do a separate batch reactor that uses only the cow dung and this will be the "control" upon which the other batches can be compared.

If you are producing biogas for actual usage at a household then you can use cow dung as the substrate without drying. So, my understanding of your context will help in giving you the proper advice.

Good luck

Because the carbon dioxide will dissolve readily in water which in turn reduces the pH of the water. If the pH is already low, the solubility of CO2 decreases and you can more accurately measure the total biogas volume with the water displacement method. Alternatively, some researchers use a strong basic solution to completely strip the CO2 and only measure methane volume. 

Yes,. You can do that. I think you should also focus on  pretreatment results before digestions. This  will give you more information about the availability of your cellulose before AD. Thanks 

Sir,

Methangenesis occur under anaerobic condition where microbes use oxygen from CO2. Whenever un-decomposed material is added to soil, under temporary submergence also, the methanogenesis will be occurring.  That is why farmers have to be advised to go for composting and then apply to field.  This process can be enhanced by adding some chemicals like alum.  The methano-bacteria is one microorganism used for the process.

CO2 + 4H2 → CH4 + 2H2O

Methane is 8-23 times danger than CO2 w.r.t. global warming.

Hence, the process needs to be stopped;

Pl. stop producing methane! SAVE EARTH!

Thanks on-be-half of all

Dear Kasun Thivanka

Sludge pretreatment prior to anaerobic digestion has been found to reduce sludge production in wastewater treatment. Sludge disintegration using physical, chemical, biological, or mechanical methods can increase biogas production and reduce sludge quantities. Ultrasonication is one of the most effective means of mechanical disintegration. This study aims to investigate ultrasonication as a means for solubilizing waste activated sludge (WAS) to enhance its digestability. Sonication was applied by the use of two different probes providing different powers and energies into the sludge after which the soluble chemical oxygen demand (sCOD) increases were measured.to improve biogas yield and methane content in anaerobic digestion of excess sludge from the wastewater treatment plant, the sludge was disintegrated by using various methods (sonication, alkaline and thermal treatments). Since disintegrated sludge contains a high concentration of soluble proteins, the resulting metabolite, ammonia, may inhibit methane generation. Therefore, the effects of protein removal from disintegrated sludge on methane production. As a result, an obvious enhancement of biogas generation was observed by digesting disintegrated sludge (biogas yield increased from 15 to 36 ml/g COD(added).day for the raw excess sludge and the sonicated sludge, respectively). The quality of biogas was also improved by removing proteins from the disintegrated sludge. About 50% (w/w) of soluble proteins were removed from the suspension of disintegrated sludge by salting out using 35 g MgCl(2) x 6H(2)O/l and also by isoelectric point precipitation at pH 3.3. For deproteinized sludge, methane production increased by 19%, and its yield increased from 145 ml/g COD(removed) to 325 ml/g COD(removed). Therefore, the yield and quality of biogas produced from digestion of excess sludge can be enhanced by disintegrating the sludge and subsequent protein removal.The type of fermentation and the reactor are important criteria involved in biomethanation of different substrates. If the total solid concentration is maintained well below 10% and in presence of activators such as Ca &/ Mg highest methane production is possible. If kitchen wastes or such inputs are used along with cattle dung, their concentration should be less than 20% and the materials should be subjected for predigestion under aerobic condition in order to enhance the production of fatty acids. different permutations shall give promising output.During an efficient biogas production, a maximized reduction of volatile solids (VS) and methane production should ideally be obtained at the highest possible organic load. This means an optimization of the utilization of both the organic material and the reactor volume available. To achieve these goals key process parameters such as pH and concentrations of fermentation products (mainly addressed by following the volatile fatty acids VFAs) need to be maintained within appropriate ranges. The pH of the biogas process is mainly governed by carbonate/bicarbonate buffering, which, in turn, to a great extent is affected by the release, formation and consumption of ammonia and VFAs, and the release of sulfide formed from sulfate and sulfite . Thus, the nitrogen and sulfur contents of the substrate can be important factors to obtain the buffering capacity required to maintain a stable pH at varying substrate composition and VFA concentrations but at the same time avoiding process disturbances due to interactions of high concentrations of ammonium and sulfide.

Please find attached herewith related research Paper and links

regards,

Prem Baboo

Methane bubbles in Lake Kinneret: Quantification and temporal and spatial heterogeneity