mahmood mahmoodi-eshkaftaki

In this research, wheat, rice, and corn residue were used as a substrate for biogas production. Due to the high amount of lignin in all three substrates (> 9.9) and in order to increase the degradability of these substrates, an ultrasonic pretreatment with a power of 150 w at 15 min was used prior to initiating enzymatic digestion process. Some physical and chemical properties including solid and volatile particles and contents of lignin, cellulose and hemicellulose were measured before and after digesting the substances; and in addition, the biogas compounds including hydrogen, methane, hydrogen sulfide and carbon monoxide was measured during digestion. The metabolic pathways of converting glucose as the main constituent of all three waste types into biogas were studied to determine the factors affecting biogas compounds. The results showed that use of ultrasonic pretreatment in all three wastes increased the breakdown of lignin structures, which decreased the content of these structures in the feedstock compared to the substrate. The amount of solid and volatile particles of the feedstock obtained from the substrate of wheat residue was 35.1% and 95.3%, respectively, which was more than that of the other substrates. The highest amounts of reduction of solid particles (19.6%), volatile particles (18%), cellulose (12.6%), hemicellulose (4.4%) and lignin (3.6%) were related to the feedstock obtained from wheat residue. Analyses of biogas compounds showed that the highest biohydrogen production obtained for wheat substrate (ppm 18000), but its biomethane production was lower than the other substrates. The highest amounts of biohydrogen production of all the substrates occurred after seven days, which was related to the butyrate acidification stage. With increasing digestion time, hydrogen production decreased while the other biogas compounds increased. One of the probable reasons was the consumption of hydrogen produced in the stages of hydrolysis, acidification and acetate formation in the stages of alcoholization and methanation. The highest amount of hydrogen production was related to the stage of butyrate formation and then acetate formation. The higher production of biohydrogen by wheat residue is most likely due to its high volume of volatile, hydrocarbon and hemicellulose compounds. While the low production of hydrogen by corn residue was due to driving the reactions towards the production of ethanol and consuming hydrogen.

With the increase of population and the level of welfare of the society, the amount of food resources (plant and animal) has increased, and thus, their wastes increase; therefore, the production of renewable fuels like biogas has increased. Biogas production and its quality are influenced by different slurry characteristics and biogas compounds, and their management is done using a computer with the help of complex algorithms, which are costly and require specialized training. For this purpose, a BioOptim application under the Android platform using Java programming language and 64-bit IDE was implemented with a high accuracy. For this purpose, some slurry characteristics and biogas compounds produced with co-digestion of different mixtures of citrous wastes and cow manure (0‒100%) pretreated with different amounts of NaOH and H2O2 (0‒3%) were studied. The measured parameters were modeled using multivariable regression models and used to imply in the BioOptim application. The evaluation results of the application showed that NRMSE of the parameters of C, N, C/N, Ca, TS, VS, K2O, P2O5, pH, CH4, CO2, and CO was lower than 0.45. For these parameters, the statistical quantities of ENS, d, R2, and IR2 were higher than 0.85, 0.95, 0.34, and 0.87, respectively. As found, the BioOptim application was only weak in determining parameter of H2S and BOD.

The quail egg is a without cholesterol food and riches of different vitamins. This food expunges the radioactive particle and the carcinogen of human’s body. For mechanizing its preparation process, the quality parameters should be modeled with computer techniques. Therefore in this research, the image processing technique was used to determine the physical properties of quail egg, then egg volume was calculated by slicing each egg and rotating the slices around its main axis. Furthermore to determine the egg weight, a regression multi-variable model and a neural network model were developed. The results of suggested methods and models in this research were compared with real values and previous methods (Hoyt model). Finally, the influence of nutrition, ventilation and female quail age on quality parameters of eggs was determined. By comparing the real volume of eggs with the Hoyt model, accuracy was 97% and with the slices-rotation method, accuracy was 100% which well shows the importance of slices-rotation method. By comparing the real weight of eggs with the Hoyt model, accuracy was 83%, with the regression multi-variable model, accuracy was 90%, and with the neural network model, accuracy was 95%. The neural network model not only presented the egg weight with high accuracy but also considered the effect of laying time which is very important for the egg weight estimation. After comparing the results, it was shown that the nutrition, ventilation and female quail age influence egg quality. The eggs of younger females were limited to spherical geometry that may be due to the mother's womb not being expanded. Furthermore, the female quails in topper cages which had better nutrition and ventilation showed more weighting and sizing. These results show that coupled the image processing and artificial neural network techniques can help very well to mechanize the preparation process of quail egg.

The goal of the present study was to study the effect of mixer speed on biogas compounds produced from semi-industrial biogas plant. The biogas was produced with slurry made by combination of 41% cow manure, 56% municipal waste and 3% kitchen waste with adding 2.38% NaOH and 3.75% H2O2 as the chemical pretreatment. Then, the effect of mixer rotation speed on mixing quality of the slurry was linked to the anaerobic microbial communities and some of physical and chemical parameters of the slurry. The results showed that by increasing the rotation speed from 60rpm to 100rpm, the amounts of CH4 and CO within the biogas compound increased by 6.6% and 71.7%, and the amounts of H2S and O2 decreased by 4% and 5.5%, respectively. This was due to decrease in the chemical oxygen demand (COD) and total volatile solids (TVS) of the slurry by 3.6% and 3.9%, respectively because of an increase in the anaerobic microbial communities by 3.7%. Furthermore, the same trend existed between the CH4 and anaerobic microbial communities of the slurry that was similar to the COD and TVS decreasing trends.