GHG from composting

Exactly! I have composted for 45 years. The nitrogen/cellulose/areation ratio is what its all about. As usual, I would be happy to reccomend users to: Rodale Press, Mother Earth News, et al. Take your math and twirl it. Composting is an art.

I've been composting for 45 years. Unturned compost will smell like anything from a cadaver to a sewer. That smell is a combination of volitial organic compounds (VOCs) and depends on the composition, heat, and areation of the components. A proper balance of nitrogen and cellulose is what most effects the outcome. I have succesfully used human waste, combined with sawdust, urine, and kitchen garbage to produce a compost with "no more odor than a warm muffin" (movie 'Battle Creek', a reference to early attemps to make a marketable Cereal, with lots of ...humm...other issues). A drum composter will reduce the afore-mentioned ingrediants to something you will be proud to put in your garden within 4 weeks. ( see Rodale Press, Mother Earth News, etc.)

I'm also getting tired of you nerdy types with your mathematics and not a clue otherwise.

Uh Oh, Looks like I may have doubled entires. I'm gonna get thrashed.

Hi, Comrade Co. Clamrod!

Typically, material that has been decomposed by methanogenic bacteria are high in unresolved metals and need to be chelated before being able to be used as fertilizer; otherwise the edible food grown in it will cause metal (especially iron) poisoning in the eater. There are ways to do this economically; and a good example of the material thus made available for gardeners and farmers is chelated post sewage-treatment sludge from your local sewage treatment plant.

Because anaerobically digested materials contain no oxygen, they also contribut little nourishment to the soil in their basic form; and must be spread in the air where the aerobic bacteria start to work on it (and in it) before being useful as compost.

Mark

Mark Thank you for your response. What is the chelating process? Could you send a reference describing the process? Is it energy intensive? Once It is chelated, how does this product compare to compost fertilizer? Would Chelating be necessary if only garden or farm waste were used? I'm assuming chelating would be required for municipal waste where the feed stock is more inclusive. You say the digest-ate would "contribute little nourishment to the soil and must be spread in the air". Wouldn't it be spread into the air when you applied it to your crop? According to a power point presentation given in Europe on biogas, the digest-ate from anaerobic digestion has "high contents of nutrients - excellent fertilizer, Nitrogen converted to ammonium, Methane emissions from manure can be avoided' decrease in the number of pathogens, less leakage of nitrogen, decrease in odor" It sounds like you would disagree with their assessment. Are they being overly optimistic?

One of the little details the "theys" miss are the intermediate steps after the anaerobic process is complete, such as the chelating and\or added oxidisers to release the beneficial nutrients.

With the aerobic process, this is achieved by the micro and macro fauna within the heap. So no futher processing is required.

One of the Good Side effects of the anaerobic process is that because it does take some time to become available to plants etc, in effect you get a slow release fertilser.

Both processes are originally natural and both have advantages.

Regards,
Sapper.

Hi, Mschultz!

Chelating normally refers to the removing of Heavy Metals from a system. This may be done by introducing chemical changes that attract them away from the system or substance containing them, and that can subsequently be removed from that system together with the attracted HMs with ease; or by instituting some other form of chemical change, such as state of matter, that makes it easier to remove them.

Any extra energy involved might only be expended in the development of chelating chemicals or process implementation.

Persons suffering from HM poisoning can often be saved by the chelation process being physically administered to their bodies.

Sludge and soil with excess HM concentrations can be chelated by the use of isolating them and adding chelating chemicals or high heat to evaporate them.

Testing has shown that chelating the fertilizing sludge during or after its being spread on crops has no effect on the concentration of heavy metals in the plants gained from uptake of nutrients from the heavy-metal-rich soil. In other words, once the plants have already eaten the fertilizer with the HMs, chelating the soil will not remove them from the plants. Also, heavy metals leaching from un-chelated fertilizer over time as it lies around on the soil tend to raise levels of HMs in the groundwater.

This means that chelating [of HMs with suspected adverse effects] should take place before spreading fertilizers from sources suspected of (or better yet tested for) having a high metal content.

But whether you want the HMs in the plant crops or not is also a factor. For example, extra zinc was added to corn chicken-feed to make the chicken eggs and meat higher in zinc content by increasing/adding a zinc source to the corn crop fertilizer by folks who think that the extra zinc was a good thing.

So chelation depends upon the end result you are trying to achieve, which metals are present/available/additives in your fertilizer, and which chelation chemicals you wish to use (probably a list is available using internet search engines or by consulting with your local agricultural college). Typically, sludge sold by sewage plants for fertilizer has already been chelated for HMs considered toxic when ingested in large amounts. But ask before you buy it anyway.

A domestic compost heap wouldn't normally have to worry about excessive HMs, unless it contained rusty tin cans or other metal waste, or was separated by rusty old screens.

Domestically sold manure makes use of aerated manure especially to remove the smell caused by methanogenic bacteria...but ridding the manure of those bacteria in the process. Using manure does contribute to the methane content of the atmosphere, but no more than just letting it lie around in a field to decompose naturally.

BTW, manure use is also beneficial because it does some of its own chelating action. Because manure can be used to some extent as a chelating chemical, the local agricultural college may have prepared for public information suggested mixture percentages of manure and sewage sludge allowing a farmer (or a gardener) to extend a limited supply of manure for fertiliser by adding sludge.

If you are curious about the unwanted HM content in a bag of manure, it might be discussed along with nitrogen-phosphorous-potassium content on the bag the manure comes in, because all types of animal manure are not the same. Or you may be able to resource that information on the web.

Mark

Methane is obtained from plant and animal waste by anaerobic fermentation. The gaseous product of this fermentation is called "biogas", and it can be used as a fuel. The methane in biogas is mixed with non-combustible gases, so that the heating value is less than that of "natural gas". The amount of methane you will get depends in part on the amount of nitrogen in the starting material.

Biogas production is actively promoted in India, which has an acute shortage of affordable fuel, especially in rural areas.

http://www.habmigern2003.info/biogas/methane-digester.html

Unconfined anaerobic fermentation produces bad odors, so it is best to confine the process in a closed digester. This also increases the methane yield. The material that remains after the production of biogas can be composted aerobically to produce a fertilizer that has little or no odor.

http://www.oregon.gov/ODA/energy_methane.shtml

It's a great way to dispose of animal waste, which is a nuisance that has also become a major source of water pollution in the U.S.

No methane - unless you are doing anaerobic composting...but both anaerobic and aerobic produces CO2 in considerable amounts from bacteria decomposition of cellulose and other carbohydrates.

Hi, Mschultz!

No. Composting is done by mainly aerobic bacteria. Aerobic bacteria are not methanogenic to a signifigant extent. And the number of methanogenic bacteria buried in your compost heap is insignifigant and subject to a very short life.

All of we other aerobic beasties give off some degree of methane along with our other waste gases because of methanogenic bacteria living in our dark, largely airless guts and participating in food digestion...some more than others. [Termites and cattle are notorious for the amount of methane they produce as aerobic beasties because their diets are largely cellulose --(think about living on an exclusive diet of beans! ), but not to the extent that methanogenic bacteria are able to do.]

On the other hand, if you were to decompose that waste matter now found in your compost heap in a sealed container with a small exit for the escape gas, or in a buried garbage dump where the methane produced by wild methanogenic bacteria living underground can percolate through the soil into the air, the bacteria in both instances would be methanogenic, with methane as their main byproduct because the presence of killing oxygen would be mostly absent.

Methanogentic bacteria are anerobic. They don't like oxygen, and don't survive well in the air your compost lives in. In order to make compost out of material decomposed by methanogenic bacteria, the material has to be thoroughly aired first to introduce the aerobic bacteria that make it into useful plant food.

Now go thou and compost in peace.

Mark

Here's a good site with info about composting and biogas:

http://www.journeytoforever.org/

Wasn't certain if the question was posed because of the possible greenhouse effect of any methane produced. You have some good answers as to what will be produced.

I read recently that methane whilst being a more potent ghg was in fact decomposed by sunlight, (and presumably the oxygen to CO2 and water). Is it more potent weight for weight because it produces two lots of CO2 etc.?

Thank you all for your response to my question about Methane generation in compost. I would like to follow up with another question: The byproduct of anaerobic digestion is a digest-ate that can be used as a fertilizer. How does this fertilizer compare to the fertilizer that comes from composting?

Hi, mshultz!

Refer to my reply #10 above, in which I addressed this question.

Mark