Methane and carbon dioxide

There are two methods of biological treatment aerobic and anaerobic (217). The aerobic systems use free oxygen dissolved in the wastewater to convert wastes in the presence of microorganisms to more microorganisms, energy required for their existence, and carbon dioxide. The anaerobic process occurs in the absence of free oxygen and converts the waste to methane and carbon dioxide, generally in deep tanks or basins, and can produce odor problems when sulfides or sulfates are present in the wastewater. 

I. Gas movement. In most cases, over 90 percent of the gas volume produced from the decomposition of sohd wastes consists of methane and carbon dioxide. Although most of the methane escapes to the atmosphere, both methane and carbon dioxide have been found in concentrations of up to 40 percent at lateral distances of up to 120 m (400 ft) from the edges of landfills. Methane can accumulate below buildings or in other enclosed spaces on or close to a sanitaiy landfill. With proper venting, methane should not pose a problem. 

Mabbit, Allen, and Andrew Parker. Methane, and Carbon Dioxide Detection Using LED Sources. Sensor Rev. 16 (1996), pp. 38-41. 

Air, carbon monoxide, methane, and carbon dioxide 25 m Carboplot 007 column at 60°. 

These tanks at a water treatment facility are used to generate a mixture of methane and carbon dioxide by anaerobic digestion of sewage. The methane produced provides much of the power needed to run the facility. 

Fig. 3 showed the catalyst stability of Ni-Mg/HY, Ni-Mn/HY, and Ni/HY catalysts in the methme reforming with carbon dioxide at 700°C. Nickel and promoter contents were fixed at 13 wt.% and 5 wt.%, respectively. Initial activities over M/HY and metal-promoted Ni/HY catalysts were almost the same. It is noticeable that the addition of Mn and Mg to the Ni/HY catalyst remarkably stabilized the catalyst praformance and retarded the catalyst deactivation. Especially, the Ni-Mg/HY catalyst showed methane and carbon dioxide conversions more thrm ca. 85% and 80%, respectively, without significant deactivation even after the 72 h catalytic reaction. 

The most probable speeds of methane and carbon dioxide are slower than the most probable speed of hydrogen, but CH4 and CO2 molecules have larger masses than H2. When kinetic energy calculations are repeated for these gases, they show that the most probable kinetic energy is the same for all three gases. 

Egli C, T Tschan, R Scholtz, AM Cook, T Leisinger (1988) Transformation of tetrachloromethane to dichloro-methane and carbon dioxide by Acetobacterium woodii. Appl Environ Microbiol 54 2819-2824. 

Oremland RS, JP Zehr (1986) Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium. Appl Environ Microbiol 52 1031-1036. 

Kinsman, R., Sauer, F. D., Jackson, H. A., and Wolynetz, M. S. (1995). Methane and carbon dioxide emissions from dairy cows in full lactation monitored over a six-month period. 

The atoms in the molecules of these pain relievers are covalently bonded. Electrons are shared between atoms in a series of single and double covalent bonds. The covalent bonds in aspirin, acetaminophen, and ibuprofen are similar to those found in methane and carbon dioxide. 

Himeno S., Komatsu T., et al. High-pressure adsorption equilibria of methane and carbon dioxide on several activated carbones. 2005 Journal of Chemical Enginnering Data 50(2) 369-376. 

BaeJ.S. and Bhatia S.K. High-pressure adsorption of methane and carbon dioxide on coal. 2006 Energy Fuels 20(6) 2599-2607. 

Srivastava [434,435], The process can be carried out under aerobic (KSARC56) or anaerobic conditions (Mic-1). The identified products include methane, lower alcohols, volatile fatty acids, and/or humic acid. For aromatic feeds the main products are phenols (and derivatives), methane and carbon dioxide. The process is carried out in a slurry phase, at pH of 7.8, under moderate stirring using a bacteria concentration less than 20%. The feed concentration could not exceed more than 50%, as stated in the patent document. In the aerobic operation, the thermophilic consortium KSARC56 is operated for 48 hours at a temperature of up to about 60°C. For the anaerobic operation a mixture of N2 C02 of about 80 20 was used. 

RM [Ralph M. Parsons] A process for methanating synthesis gas, i.e. converting a mixture of carbon monoxide and hydrogen to mainly methane and carbon dioxide. Six adiabatic reactors are used in series, and steam is injected at the inlet. Under development by the R. M. Parsons Company in 1975. 

The major volatile product from the irradiation of Bis-A PSF at 150°C was sulfur dioxide, which was produced with G(SO ) 0.146. This is consistent with previous measurements at 30°C, 125°C and 220°C (1,2). Other volatile products observed were hydrogen, methane, and carbon dioxide. The G values for the various gaseous products are compared with literature results for irradiation at 30 C in Table II. 

A variety of photocatalyzed decarboxylation reactions on Ti02 powder including the decomposition of acetate to methane and carbon dioxide and the breakdown of benzoic acid yielding predominantly CO2 have been reported by Bard and coworkers (23,24). Evidence for the occurrence of these "photo-Kolbe" reactions has stimulated the search for other organic reactions that might be photochemically initiated by excitation of semiconductors and extensive work in this area is in progress (25). 

Ti02, with a band gap of 3.2 eV, was successfully used for the photooxidation of acetate ion in acetic acid, a photochemical version of the Kolbe reaction (Kraeutler et al., 1978). The main products formed were methane and carbon dioxide, in addition to small amounts of ethane. The latter is the major product... 

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