الفهرس 
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Abstract
The anaerobic digester has great potential for the efficient conversion of agricultural, municipal, and household waste into green energy. By providing agricultural waste treatments such as microwave and ultrasonic treatment an option to significantly reduce reactor size and raise its efficiency, thus, the economics of anaerobic digestion of these materials can also be improved. The current study aimed to evaluate the effectiveness of the effect of microwave and ultrasonic pre-treatment using six similar laboratory anaerobic digesters fed fresh cow dung. The current study was carried out using 10% of total solids, with a rotation speed of 120 rpm of mechanical stirring. A catalyst for fermentation was used with a ratio of 3% solid matter and 10% of the fermenter volume. The experimental conditions for the treatments were as follows: - Three different MW powers of 100, 450 and 800 W - Three different MW exposure times of 5, 10 and 15 min - One US frequency of 30 kHz - Three different US wave exposure times of 5, 10 and 15 min - Concentration of 10 % TS by dry weight - Hydraulic Retention Time HRT of 20 days Fresh cow dung used in this study was obtained from the dairy animal farm of the Faculty of Agriculture, Alexandria University, Alexandria Governorate. Cow dung was taken directly and analyzed for chemical properties such as total solids, volatile solids, organic carbon and total nitrogen. The experiment was carried out under the conditions of a stirring speed of 120 rpm. The stirring time was 15 minutes and stirring was done every 4 hours. The digesters are installed inside a water bath to provide and maintain the average digestion temperature at 40 ± 2 °C. The system is evaluated on the basis of the daily biogas production rate and the percentage of methane in the produced gas. The evaluation also includes an estimate of energy production, energy consumption and net energy gained. The net energy gained and the obtained results can be summarized as follows: - Biogas production during the batch Condition at 10 % TS to determine residence time and feed rate The results indicated that biogas was produced from the first day after the digesters feeding. This may be due to the active starter culture that was added to the fresh cow dung. The results showed that the biogas productivity increased with increasing time, reaching its maximum value was 3.61 L/day at 16 days HRT. - Biogas production rate at continuous feeding conditions 1. The results showed that biogas production increased in all treatments by increasing the exposure time from 5 to 10 min. 2. The exposure time at 10 min gave the maximum biogas production rates with the initial treatment using different microwave powers and at 15 min using ultrasonic compared to other treatments, which are 5 and 15 min with microwave and 5 and 10 min with ultrasonic. where the average rates of increase at 10 min were 96.82, 160.09 and 135.76% using 100, 450 and 800 W compared to the control, respectively, and the average rate of increase at 15 min was 63.1% using ultrasonic 30 kHz compared to the control. 3. The obtained results showed that the maximum methane content in biogas production was achieved at the exposure time of 10 min with all treatments of 100, 450, 800 W and 30 kHz, which gave values were 70.13, 74.09, 67.39 and 68.02% compared to the control, respectively. The difference between the maximum and minimum values of methane biogas were 21.92, 25.88, 19.18 and 19.81% with the treatments of 100, 450, 800 W and 30 kHz compared to the control, respectively. 4. The obtained results also showed that the value of microwave power and ultrasonic was a significant effect on the methane content of biogas. 5. The maximum energy production was 25.772 kWh, which was achieved when the treatment was 450 W and the exposure time was 10 min, followed by 24.232 kWh when the treatment was 450 W and the exposure time was 5 min, then 22.432 kWh when the treatment was 100 W and the exposure time was 10 min, then 22.222 kWh when the treatment was 100 W and the exposure time was 10 min. The treatment is 800 W and the exposure time is 10 min then 22.131 kWh when the treatment is 450 W and the exposure time is 15 min then 21.476 kWh when the treatment is 30 kHz and the exposure time is 10 min. While the minimum produced energy was 5.311 kWh, which was achieved when controlling. 6. The energy consumption was 3.687 kWh for the maximum energy production and 2.659 kWh for the minimum energy production. 7. The net energy gained was 22.085 kWh, which was achieved when the treatment was 450 W and the exposure time was 10 min, followed by 20.454 kWh when the treatment was 450 W and the exposure time was 5 min, then 19.056 kWh when the treatment was 100 W and the exposure time was 10 min, then 18.444 kWh at treatment 450 W and the exposure time 15 min then 18.371 kWh at treatment 800 W and exposure time 10 min then 17.114 kWh at treatment 30 kHz and exposure time 10 min. While the minimum produced energy was 2.652 kWh, which was achieved when controlling. Perform cost analysis of the biogas production process: - Benefits of biogas and bio-fertilizer production for plants The best results for both projects were given as capital costs, variable costs, annual income and annual net income of 4650, 2976.24, 6740.52 and 885.72 L.E for microwave units, respectively. While the capital costs, variable costs, annual income and net annual income were 6950, 432.68, 6701.6 and 681.08 L.E for ultrasonic units, respectively. -Economic feasibility of biogas production The Net Present Value (NPV) and the Internal Rate of Return (IRR) in the economic analysis were EGP 24192.11 and 97% for microwave units, respectively. While the Net Present Value (NPV) and the Internal Rate of Return (IRR) in the economic analysis were EGP 21729.23 and 64% for the ultrasonic units, respectively. This indicates that the investment opportunity is a profitable investment because it contains profits in excess of theexpenses when implementing both of two systems.