Browsing by Author "Teshome, Worku (Asst. Prof.)"
Item Biogas Production by Anaerobic Co-Digestion of Food Wastes with Goat Manure(Addis Ababa University, 2017-12) Gidey, Kiros; Teshome, Worku (Asst. Prof.)Due to the rapid population growth and unmanageable urbanization, one of the burning issues faced by the world today is management of all types of wastes. This study has been conducted on the production of biogas by anaerobic co-digestion of food wastes with goat manure. Food waste (FW), goat manure (GM) and their mixtures were anaerobically digested for 40 working days. The proximate composition analysis of the FW and GM had shown that, whereas the GM was higher in TKN value (2.1%), the MFW was higher in C/N ratio (34.0). During this study FW and GM were combined into five MFW to GM mixing ratios of 1:0, 1:1, 2:1, 1:2, and 0:1; and a total of 45 MRs (nine for each mixing system) were prepared in 1-liter plastic bottles. The pH of these MRs was adjusted to 6, 7, and 8 by adding 10 N NaOH. Three water baths were set to three temperature values of 30o C, 35o C and 40o C in which the 45 plastic bottles of 1-liter capacity (15 plastic bottles in each water bath) as main digesters were immersed. The experimental AD of this study took 120 days (40 working days for each experimental setup) to produce biogas. The combination systems of the MFW and GM for co-digestion overcomes the imbalanced C/N ratio of the MFW. The efficiency of the mono-digestion of MFW only, GM only and co-digestion of the MFW with GM were studied and compared. Statistical design of the experiments and data analysis was investigated using the general factorial design. Statistical test had shown that the model "F values" for both the responses, the biogas volume and methane content in the biogas were statistically significant (P<0.05). The optimum MRs between the MFW and GM were found to be the 1:1 and 1:2 MRs at process parameters of 35o C and initial pH of 7.0. The cumulative biogas generated at these conditions were found to be 11.4 and 17.3 liters respectively from the MRs of 1:1 and 1:2. Averagely, higher methane yield of 61.1% and 63.5% respectively was obtained by the codigestion of MFW with GM at 35o C and initial pH value of 7.0 from the MRs of 1:1 and 1:2. The results noted from this study showed that the anaerobic co-digestions of MFW with GM was better than mono-digestion of the single waste alone for biogas generation.Item Extraction of Natural Dyes from Locally Grown Plants in Ethiopia and Dyeing of Cotton Fabrics(Addis Ababa University, 2017-11) Girma, Biratu; Teshome, Worku (Asst. Prof.)Natural dyes were the only colourants used for colouring of textiles beginning from ancient times to nineteenth century. Using of natural dyes are safe for human’s health and environmentally friend even though they have drawbacks such as not easily available in the market, needs complex processing steps and relatively poor fastness properties when compared to synthetic dyes. The purpose of this paper was to extract dye from impatiens tinctoria, allo and wild strawberry (Fragaria Vesca L.) plants grown in Ethiopia by using aqueous extraction method. Next crude dye yield of the extact was calculated and un-mordanted and pre-mordanted cotton fabric was dyed. For impatiens tinctoria the maximum yield was 21.3% while the least was 7.8%, in case of allo the maximum yield was 17.4% while the least was 4.5% where as for wild strawberry, the maximum crude dye yield was 18.4% while the least was 7.7%. Dyed fabrics were analyzed in terms of colour strength (K/S) and colour appendices (CIE L* a* b*) by using Data colour 6100. Dyed cotton fabric was also analyzed for its fastness properties like: rubbing fastness (dry and wet) by using crock meter, washing fastness (colour change and colour staining) by using atmospheric washer while light fastness was determined by solar box 1500. The results showed that cotton dyed by pre-mordanting with alum and ferrous sulphate showed increased depth of shade and improved fastness as compared to un-mordanted cotton fabric. The CIE L* a* b* result showed: For the wild strawberry, L* values were in the range of 42.56 to 84.26, a* lay in the range of 0.97 to 4.62 and b* values extended from 0.92 to 24.42; Allo lightness(L*) lay in the range of 34 to 85.63, a* values extended in between -2.01 and 4.9, b* lay in the range of 5.94 to 41.23 and Impatiens tinctoria lightness lay in the range of 65.23 to 81.31, a* values lay in the range of 3.52 to 4.70, the values of b* extended in the range of 2.84 to 13.92. The values of k/s also varied in between 0.381 to 14.12. The fastness results (>3 in case of washing and rubbing fastness and >5 for light fastness) indicated that they were in the range of commercially acceptable standards.Item Modeling of Air Pollutant Dispersion and Analysis(Addis Ababa University, 2010-11) Anteneh, Muheye; Teshome, Worku (Asst. Prof.)This work has been carried out to develop a three dimensional modeling program for pollutant dispersion. The program solves partial differential equation by integrating into one mathematical equation and then various data are taken from literature s and primary sources for verification of the program. The effects of meteorological and stack parameters on dispersion of pollutants ,like wind velocity, ambient air temperature, atmospheric stability, exit temperature, velocity ,concentration and stack height were studied and considered in the program. Several illustrations for reducing maximum ground level concentration using the program are given. The output results from the program are presented in different forms. Different simulation runs and observations were made that clearly illustrate the utility of the program in helping decision makers about air pollution control and effects of different variables in pollution.