Browsing by Author "Desta, Solomon"

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    An Assessment of Educa Tlonal Television in Promoting Teaching - Learning in Selected Secondary Schools of Addis Ababa
    (Addis Ababa University, 2010-06) Desta, Solomon; Woldegerima, Hailesillassie (Associate professor)
    The ultimate purpose of this study was to investigate some of the factors that facilitate or impede Educational Television programs in promoting teaching-learning with particular reference to secondary schools of Addis Ababa. Keeping in view the nature and requirement of the present study, "descnjJtive survey method" was adopted to explore and assess the educational television programs watched and its effect in the teaching and learning process in the selected secondary schools of Addis Ababa. Accordingly, to collect the necessCllY data related literature was collected, reviewed and discussed. Pilot study was carried out to help improve the validity and reliability of students' questionnaire. Subsequently, students' and teachers' questionnaires, principals and educational media personnel interview and classroom observation were designed and administered as the instrument of the study. To this effect. 300 students, J 00 teachers, five school principals and five media personnel were randomly selected Fom the randomly selected 8 secondary schools and Department of JeT so as to give their responses on designed questionnaires and interview. Questionnaire was the ,rwin instrument used to collect data, on the other hand interview and classroom observation were administered as second instruments for the study. The responses were tabulated, discussed and analyzed by employing percentage frequency distribution and were advanced using different data analyzing tools like mean, graphs. histogram etc. This research appraised the interest as well as attitude of students and teachers towards Television education, on top of this it reviewed factors that facilitate or impede television education and factor that trim down teacher's role in television classroom. Furthermore it appraised the differences in motivation and achievement of television users and nonusers in public and private schools. From the findings Pace of the television program presenters, problem in understanding the lesson and Language problems were considered major hindering factors for the follow up of students as evident. From the study it was concluded that pace and language problem abridged the means for effective communication and transcription, students were not fully interested in educational television programs. The understandability of the plasma television is questioned. Limited share of classroom teacher's time did not allow playing the roles and techniques employed in plasma television teaching-learning. The recommendations given were that the television programs have to be revised to meet the pace; relevance and language level of the students. Language development at early level and early English television programs are required to assist students to follow the Education Television programs.
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    Integration of Fenton Oxidation and Biological Process with Sequencing Batch Reactor for the Treatment of Textile Wastewater
    (Addis Ababa University, 2020-02) Desta, Solomon; Zebene, Kiflie (PhD); Hulle, Stijn Van (PhD) Co-Advisor
    study was mainly aimed to investigate the treatment efficiency of the integrated system of biological oxidation and homo catalytic advanced oxidation process for the treatment of textile wastewater. Mineralization of a methyl orange dyes using artificial solar Fenton oxidation, degradation of a Basic Blue 41 dyes and real textile waste water with conventional Fenton oxidation were examined at laboratory scale in batch experiments using Box–Behnken statistical experiment design. Dyestuff, hydrogen peroxide (H2O2) and ferrous ion dose (Fe2+) concentrations were selected as potential independent factors for simulated dye aqueous solutions while for real wastewater Fenton reagents (H2O2 and Fe2+ ) and pH were selected as independent potential factors. Besides, color and total organic carbon (TOC) removal were measured as desired response functions for artificial solar Fenton oxidation while color and chemical oxygen demand (COD) were selected as desired response for conventional Fenton oxidation processes. The total time of irradiation used in the case of artificial solar Fenton oxidation for all the experimental runs were 20 minutes while the total reaction time for conventional Fenton oxidation processes was 1hour. Perturbation plots showed that iron dosage was the key process factor on the responses for both solar and conventional Fenton processes. At constant dye stuff dose, color, TOC and COD removal increased with increasing H2O2 and Fe2+ concentrations up to a certain level. High concentrations of H2O2 and Fe2+ for a constant dye stuff dose did not result in better removal of color ,TOC and COD. The optimum ratio of Fe2+ / H2O2 /dyestuff which gives a complete color removal and 96% TOC removal for the highest level of dye dose for artificial solar Fenton was found to be 72 /1386 / 255 (mg/L). In this regard, Percent color removal was higher than TOC removal. During degradation of Basic Blue 41 dye, the optimum ratio of H2O2/Fe2+/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195mg/L /90mg/L /255mg/L while in the case of real wastewater degradation, the optimum ratio of that gives 87% color removal and 79% COD removal were Fe2+/H2O2/pH (500.4mg/L/5187.6mg/L/2.9). In this regard,, Fenton oxidation using optimum Fenton reagents at a pH of 2.9 is effective for the treatment of acrylic fiber processing textile wastewater. Subsequently, real textile wastewater was taken and treated with a sequencing batch reactor (SBR) using a biomass taken from domestic wastewater treatment plant. Cycle period, air flowrate and sludge retention time (SRT) were initially optimized using the response surface methodology (RSM). The optimum ratio of cycle period/ air flowrate/SRT which indicated 57% COD removal and 54% color removal was found to be 25 h /15L/h /16d. Two types of wastewater substrate concentrations and various hydraulic retention time (HRT) were used at optimized conditions. COD removal, color removal, sludge volume index (SVI) and mixed liquor suspended solid (MLSS) were measured. The maximum COD removal (73%) and color removal (65.8%) were obtained at an organic loading rate of 0.078 kg COD/m3d. SVI at the optimized condition was found to be 90-92 mL/g. A first order kinetic model was used to represent the degradation of textile wastewater. Finally, the removal of COD and color studied on a real textile wastewater using a single stage of Fenton oxidation, (SBR) and also with the combination of SBR with Fenton oxidation. Optimum amount of chemical reagents and SBR process factors were used. The effluent obtained from SBR at steady state conditions indicated a maximum COD and color removal of 74.1% and 64.6% respectively. The effluent obtained from Fenton followed by SBR (Fenton +SBR) at steady state conditions indicated a maximum COD and color removal efficiency of 86.3% and 84% respectively. while SBR followed by Fenton (SBR+ Fenton) for three Fenton oxidation experimental runs indicated a maximum COD and color removal of 80.2% and 73.6% respectively
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    Performance Appraisal Practices And Challenges In Branna Printing Enterprise
    (Addis Ababa University, 2018-06-20) Desta, Solomon; Bekalu, Wubshet (PhD)
    It was not known and no research exists that examines the practice and challenges of performance appraisal practices in Branna Printing Enterprise. Therefore, the purpose of this study was to assess the practice and challenges of performance appraisal in Branna Printing Enterprise. The study tries to address the basic questions of practices of performance appraisal system, the challenges, the strengthens and weakness and the consequences of performance appraisal system in BPE. To answer these questions, the study was employed through descriptive design in which data from employees and management have been collected using questionnaires and interviews. The total number of staff at BPE was 305 and for this study simple random sampling technique was used by taking 92 employees to fill in the adapted questionnaire, which was the main data collection instrument. The data gathered from the questionnaire have been compiled by using SPSS software. Descriptive statistics method had been used for analyzing data obtained from questionnaire and data gathered from interview and focus group discussion and document analysis have been analyzed contextually. The result of the analysis will be presented using tables. The findings of the study and the outcome of the research presented at the end