In the composting process, the degradation of organic carbon present in the organic matter leads to the formation of either Co2 or CH4 or both and later generation of volatile fatty acids or low molecular weights acids. Can anybody describe(in detail) the exact chemical/ biochemical reaction mechanism??? How these products are being formed during composting and in which condition?
Dear Loopa
Aerobic composting is the decomposition of organic substrates in the presence of oxygen air. The main products of biological metabolism are carbon dioxide, water and heat.
Composting involves the accelerated degradation of organic matter by microorganisms under controlled conditions, in which the organic material undergoes a characteristic thermophilic (45 to 65C) stage that allows sanitization of the waste by the elimination of pathogenic microorganisms, where microorganisms such as bacteria, fungi and actinomytes liberate heat, carbon dioxide and water.
The respiration test is a measure of the activity of the micro-organisms in the compost heap and thus, of the stability of the compost produced which provides a measure of whether the rate of CO2 generation has dropped low enough for the compost to be stable. Carbon dioxide is released as one of the major gaseous products during the composting of organic matter in the presence of oxygen.
Regards
Dr Nuhaa Soobhany
Dr. Nuhaa Soobhany! Thank you for your reply. If you could provide a detail chemical mechanism, reaction pathway of different constituents of organic matters (like protein, carbohydrate, lipid, etc.) at each stage (like mesophilic, thermophilic, less oxygen condition), it will be highly appreciated! Again how the low-molecular-weight acids are formed in which stage in which condition???
Please see the following paper:
Jakobsen, S. T. (1992). Chemical reactions and air change during decomposition of organic matters. Resources, Conservation and Recycling, 6(3), 259–266. doi:10.1016/0921-3449(92)90035-z
Best regards
Vit
What if you look at Article The Characteristics of Carbon, Nitrogen and Sulfur Transform...
Lopa Pattanaik
Dear Loopa,
I propose to you to interest at another way of thinking composting and organic matter biodegradation. We are measuring another very interesting property of transformed organic matter in the soils: the microorganisms can produce high value molecules, named fulvic and humic acids, through enzymes like lignin peroxydase. This enzyme is oxydising lignin but can even snthesize humic acids controlling the level of phenols inside the compost. An article of 2008 (Bioresource Technology, vol 99, Issue 14, P 6037-6045) has demonstrated that more we measure humic acids inside compost, more the Eh is reduced. Composting is a mix of oxydation and reduction metabolisms, and the final result is the production of molecules able to preserve the homeostasis of the environment: the optimal level of Eh and pH inside the organic matter. The phases of thermophilic development is an industrial organisation to degrade green wastes, and go fast to manage high volumes. Today, in agriculture, we prefer to fertilize soils wich more fresh material and wait for a normal transformation of organic matter. To gain a buffer effect created by microorganisms, fbuffer effect that you can verify measuring the Eh and pH in the soil. Go and see the articles of Olivier Husson from the CIRAD, and I add another article very important for the future of the management of organic wastes: Archives of Agronomy and Soil Science, N. R. Pandit et al, Nutrient effect of various composting methods with and without biochar on soil fertility and maize growth. You will find that another treatment of wastes is anaerobic metabolism, giving high reduced compost, rich in energy. Soils and composts are made of aerobic and anaerobic metabolisms, this is producing electrochemical polarity. And I suppose that it is a part of the immunitary system of soils.
Nuhaa Soobhany Isabella Tomasi Getachew Gebreeyessus Vit Mateju ... Thank you all for giving your time to answer my query
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