الفهرس 
Energy Sources in EgyptOnly 14 pages are availabe for public view
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Abstract
Scientists and experts have agreed that the petroleum era will sooner or later come to an end and nations will be struggling to meet their oil and gas needs, which will possibly open the door for a third world war. For this reason, Egypt must enhance the biogas production technology as a renewable source of energy in order to secure the coming generations. There are numerous biomass resources in Egypt, such as animal,agricultural and industrial organic wastes which can be used to produce biogas by anaerobic digestion process as one of the biochemical treatment technologies. Biogas is a mixture of gases produced by methanogenic bacteria for biodegradable materials in an anaerobic condition which is mainly composed of methane (CH4), carbon dioxide (CO2and low amount of other gases.An experimental investigation has been carried out to study the effect of the operating temperature, feedstock composition, mixing ratio, organic waste type and total solid content on the biogas productivity. The experimental work was performed using three identical laboratory scale batch feeding anaerobic digesters with a capacity of 180 liter for the working volume. Each of the digesters was designed to operate under three operating temperatures which achieve thermophilic (55 ± 2 ºC), mesophilic (40 ± 2 ºC)< and ambient operating conditions during the same retention time of 31 days or one month. Six experimental operation tests were carried out using different eight liquid mixtures of organic wastes. Five of these liquid mixtures were used in five operation tests under the different operating temperatures, while the other three liquid mixtures were used in one operation test under the same operating temperature of mesophilic condition.The different mixtures of organic materials which have been used in the
experimental tests included pure cattle manure, pure hen manure, cattle manure mixed with rice straw, cattle manure mixed with hen manure, mixture of cattle and hen manures mixed with wet bean stems and cattle manure mixed with rabbit manure. For each test, the mixture of wastes was mixed with water and prepared to feed each digester.And then, the total solid content for the liquid mixture which was obtained from each digester was measured at the beginning of each operation test. PH value was measured daily for a specified sample of liquid mixture which was obtained from each digester.
Moreover, the generated biogas volumes were measured daily in liter by using gas collecting systems. Furthermore, the ambient temperature around the biogas production units was measured daily via mercury thermometer. Also, the pressure of the product gas was measured daily via U-tube manometer. Finally, a chemical analysis was performed for some biogas samples which were drawn from each biogas production unit.
from the experimental work, it could obtain some significant results which show the effect of the important factors mentioned above on the biogas production. The results indicated that, the total biogas production obtained under thermophilic condition is always higher than that given in the other operating conditions. For instance, for the third operation test, under thermophilic condition the product biogas was higher than that was given under mesophilic condition by 44.65%.
The liquid mixture composed of cattle and hen manures produced higher biogas
production (5755 liter) than that was given in the other mixtures under thermophilic condition. Also, the liquid mixture composed of cattle manure, hen manure and wet bean
stems produced the highest biogas production (3407 liter) with respect to what was produced by the other used liquid mixtures under mesophilic condition. For the same liquid mixture of pure cattle manure and water; the biogas production increased by 64.2%, when mixing ratio of water increased by about 10%, under the same operating temperature. Also, the product biogas form liquid mixture of cattle and hen manures increased by 14.2%, when using excess mixing ratio of hen manure equal
46.7%under the same operating temperature. As well, using liquid mixture containing pure hen manure produced much more biogas than what was obtained from liquid mixture containing pure cattle manure by 27.8%, under the same operating temperature.
It was observed that the maximum biogas production occurred for a value of initial total solid content equal to 10.1% under mesophilic condition. from a chemical analysis for some samples of the product biogas in the sixth operation test, it could obtain the maximum methane content and the corresponding biogas heating value equal 83.72% and 31.18 MJ/m3, respectively under mesophilic condition. Finally, all of the measured pH values in all operation tests were higher than 7.