Browsing by Author "Asha Singh"

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Biomethanization of coal to obtain clean coal energy: A review
(2012) Asha Singh; Prakash Singh; M. Singh
This paper entails a review on the possibility of methanization of coal using microbial tool. Biomethanization process of coal begins with biodegradation of coal by specific bacteria and fungi. As a result of this, major polymers present in coal like proteins, polysaccharides, nucleic acids and lipids are hydrolyzed to monomers like aminoacids, sugars, purines, pyrimidines and long chain fatty acids. Their subsequent fermentation forms hydrogen, CO2 and a number of reduced compounds like alcohols, short chain fatty acids, organic acids and certain aromatics. The oxidation of these reduced compounds further leads to the formation of acetate, hydrogen and CO 2, methylated compounds and several intermediate compounds. Syntrophic relationship exists between fermenting bacteria and methanogens. The resultant oxidized compounds of fermenting bacteria are gradually utilized by specific methanogens to form methane. Hydrogenotrophic methanogens utilize H2 and convert CO2 into methane. Whereas acetate is utilized by acetoclastic methanogens to generate methane. The methylated compounds are utilized for methane formation by methylotrophic methanogens.
Desulfurization of selected hard and brown coal samples from India and Indonesia with Ralstonia sp and Pseudoxanthomonas sp
(2012) Asha Singh; Prakash Singh; Aniruddha Kumar; M. Singh
The present paper entails the investigations on the removal of total sulfur (St) from the coal samples of four coal and lignite fields of India and Indonesia by Ralstonia sp and Pseudoxanthomonas sp. Minimum desulfurization (in relative%) was observed in Nagaland coals (India) which contain maximum quantity of St (6.86%) among the samples of the studied area while higher removal (in relative%) was observed in coals containing relatively low quantity of St. Nevertheless, a positive correlation exists between St and removal percentage in samples of all coalfields indicating an increase in removal% with increasing concentration of St. The removal percent (with respect to its initial St) by Pseudoxanthomonas sp in the investigated area is in order of: Vastan (mean 41.84%) > Indonesian (mean 34.16%) > Nagaland (mean 18.26) coals. In case of removal by Ralstonia sp the order of removal % can be put as: Vastan (mean 45.50%) > Rajpardi (mean 42.93%) > Indonesian (mean 20.22%) > Nagaland (mean 11.83%) coals.
Petrographic considerations in demineralization of coal with bacteria: A new dimension in understanding the clean coal technology
(Multi-Science Publishing Co. Ltd, 2014) Prakash Singh; Asha Singh; Aniruddha Kumar; Mahendra Singh
The present study reveals that there is close relation between the petrographic composition of coal and removal of major, minor and trace elements/metals with bacteria. While increase in total huminite concentration has favoured the removal of Cr, Ni, Pb and Mg, there is good removal of Cd and Cu with increase in liptinite content. Inertinite is found to be favourable for the removal of Cd, Fe and K. It is therefore important to take into consideration the petrographic composition of coal when trying for the beneficiation of coal with bacteria. This will be helpful in designing suitable strategy for the removal of environmentally sensitive elements/metals with the help of bacteria and to obtain clean fuel from coal.