School of Chemical and Bio Engineering

Permanent URI for this college

http://etd.aau.edu.et/handle/12345678/127

Browse

Now showing 1 - 20 of 412

Activated Carbon Preparation and Characterization from Flax Straw for Removal of Pb (II) Ions from Aqueous Solution and Industrial Wastewater
(Addis Ababa University, 2021-09) Tayto, Mindahun; Shegaw, Ahmed (PhD)
There are different modern technologies to remove heavy metals from industrial effluent. However, applying these modern technologies is impossible in all situations. Hence, investigating alternative technologies like adsorption by AC for such kinds of problem is very important. Considering this, the aim of this study was to prepare AC from flax straw and investigate its potential for the removal of Pb (II) ions from aqueous solution and paint industry wastewater. AC was prepared by chemical activation method using H3PO4 as activating agent. The effects of activation time, activation temperature and activating agent concentration on yield and iodine number were studied by using RSM. The effects of initial Pb (II) ion concentration, adsorbent dose, contact time and pH on removal efficiency were studied by using synthetic wastewater prepared from lead nitrate on a batch mode. The collected wastewater sample was characterized before and after treatment according to APHA methods. AC was characterized and results showed that the flax straw AC had 8.04% of moisture, 6.04% of ash, 18.615% of volatile matter, 79.421% of fixed carbon, 459.807 mg/g of iodine number and surface area of 489.455 m2/g. Physico-chemical characteristics revealed that raw wastewater had a concentration of 3.95 mg/L Pb (II), 158.52 mg/L BOD5, 2482 mg/L COD, and 652.667 mg/L TSS. The highest removal efficiencies of Pb (II) metal ion which was achieved from aqueous solution and paint wastewater were found to be 95.16% and 78.73%, respectively. The experimental data are fitted with pseudo-second order model and adsorption of Pb (II) on flax straw AC fits the model of Langmuir very well. The results suggested that flax straw AC can be used as adsorbent to remove Pb (II) ion from paint industry wastewater.
Activation of Raw Bentonite (Afar Region) Using Sulfuric Acid for Rapeseed and Niger Seed Oil Bleaching
(Addis Ababa University, 2017-06) Shemsu, Leena; Tekola, Beteley (PhD)
In this study, a two-stage process was conducted. The first one was carrying out the activation process of raw bentonite at different conditions and the optimum parameter was chosen. The second process was bleaching of Niger seed oil and rapeseed oil using the chosen activated bentonite. The raw bentonite collected from Gewane in Afar region was activated by sulfuric acid and the design of various experiments in order to assess and simulate the effects of the acid activation of raw bentonite on the bleaching capacity of Niger seed oil is described. Two key parameters of the acidic activation, namely acid concentration and activation temperature, were considered. The highest bleaching capacity was obtained around 3M acid concentration and at 90oC of activation temperature as optimal activation. The raw and activated bentonite at optimal condition was characterized by XRD, FTIR and SEM with EDS. The results of the XRD showed that the raw bentonite is composed of montmorillonite, quartz, muscovite, hematite, feldspar and cristobalit. X-ray and FTIR data confirmed that acid activation affects both the octahedral and the tetrahedral sheets. The results of the analysis by Energy Dispersive Spectroscopy (EDS), showed that, presence of silica, alumina and iron as major constituents, along with traces of sodium, potassium, magnesium, calcium, and titanium in the form of impurities. These exchangeable cations were removed partially by acid attack. Full factorial experimental design was employed to correlate the bleaching parameters (temperature, time and dosage of clay) to the percentage color reduction for Niger seed and rapeseed oil bleached. The result showed that the optimum condition for the bleaching process was a temperature of 900C, a period of 30 minutes and 4 % clay dosage which resulted in 94.37% bleaching of the Niger seed oil. For rapeseed oil, the maximum bleaching efficiency, which is 96.01%, was obtained at 110 0C, a time period of 45 minutes and 1% clay dosage. The experimental result was in agreement with the model prediction. Generally, the study has shown that the clay is a good adsorbent for the bleaching of both oils. This research has further established that acid activated bentonite has the power to remove not only pigments but also reduce the free fatty acid of unbleached oils. Keywords: Bentonite, Acid activation, Characterization, Bleaching, Niger seed oil, Rapeseed oil
Adaptive Control Design for a MIMO Chemical Reactor
(Addis Ababa University, 2004-07) Yimam, Abubeker; Venkatanarasaiah, D. (PhD)
The major disadvantage of non-adaptive control systems is that these control systems cannot cope with fluctuation in the parameters of the process. One solution to this problem is to use high levels of feedback gain to decrease the sensitivity of the control system. However high gain controllers have two major problems: large signal magnitude and closed loop instability. The solution to this problem is to develop a control system that adapts to changes in the process. This paper presents the design of adaptive controller to a MIMO chemical reactor. The proposed adaptive controller is tested by using Math lab Simulink program and its performance is compared to a conventional controller for a different situation. The paper demonstrated that while the adaptive controller exhibits superior performance in the presence of noise the convergence time is typically large and there is a large overshoot. To resolve these problems of adaptive controller, the proposed controller is redesigned by modifying the adaptation law. And the results show a significant improvement in the performance of the adaptive controller without excessive increase in the adaptation rate. life of the low and middle income inner-city residents of Addis Ababa. Financial, institutional and legal problems are also seen as the major problems that hinder the implementation of LDPs in Addis Ababa
Adsorption of Heavy Metal from Constituent Waste Water by Tea Waste Adsorbent
(Addis Ababa University, 2016-06) Oljira, Lalise; Kiros, Solomon (PhD)
Most industries such as electroplating, textile, fertilizer, batteries, leather, and others in less developed countries discharge huge volumes of untreated wastewater into water bodies. The industrial wastewater may contain toxic chemicals in excess of the threshold level when released into the environment, particularly to the aqueous environment and soil; significantly degrade the quality of the water thereby affecting river health substantially and subsequently human health. There are several techniques for removing toxic chemicals such as ion exchange, membrane filtration, adsorption, irradiation and chemical and biological treatments. However, the adsorption method is believed to be the better option because it is cost-effective, efficient, simple and easy to operate, and environmentally friendly according to many studies. Accordingly, this method can be a preferable option for developing countries like Ethiopia, where advanced treatment technologies for high volumes of toxic industrial waste water are unaffordable. The aim of this work was to determine the potential of tea waste (TW) as a useful adsorbent for the removal of copper and zinc ions from aqueous systems. The study was conducted using batch experiments with constituted wastewater having copper and zinc ion concentration of 1000 mg·L-1. The effects of initial concentration, contact time and pH on adsorption efficiency were investigated. Adsorption isotherm was also studied. Generally, the result showed an increase in removal efficiency with increase in contact time, pH and decrease of initial concentration. The adsorption equilibrium data correlate well with Freundlich model and Langmuir model respectively for zinc removal and copper removal with regression coefficient (R2=0.9913, R2=0.981). The results showed that efficiencies of (TW) for the removal of copper and zinc ion were 95.98% and 99.80% respectively at optimum point of 5pH, 10ppm, and 120min. These results clearly indicate the efficiency of tea waste (TW) as a low-cost adsorbent for treatment of wastewater containing copper and zinc ions. Therefore, it is recommended that tea waste can be used, as a low cost and abundant source for the removal of heavy metals as an alternative to more costly materials. KEY WORDS: Copper, zinc, toxicology, adsorption, tea waste, batch study, atomic adsorption spectrometer.
Adsorption of Methylene Blue Dye from Synthetic Wastewater using Chitosan/graphite Composite Adsorbent; Statistical Optimization
(Addis Ababa University, 2023-11) Soliyana Teshome; Shimelis Kebede (PhD)
The study aimed to synthesize a chitosan/graphite composite (CGC) for methylene blue dye removal from synthetic wastewater using the impregnation method. Expanded graphite was prepared by reacting graphite with H2SO4 and H2O2 at room temperature, then washed, dried, and heated. The specific surface area of graphite increased from 1193.75m2/g to 1223.648m2/g. The composite adsorbent material was synthesized using the impregnation method, with chitosan to expanded graphite ratio of 75:25. The CGC was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller (BET) method, scanning electron microscope (SEM), and point of zero charge analysis. The optimized experimental design resulted in 98.61% removal efficiency at initial concentration of 5.24 mg/L, pH of 9.98 and contact time of 95.43. The adsorption of methylene blue dye onto CGC was best fitted with Langmuir isotherm, with an R2 value of 0.9974 and adsorption capacity of 98g/g. The kinetics of adsorption were best fitted to pseudo-second order with an R2=99.39.
Adsorption-Anaerobic Digestion coupling process for molasses vinasse Treating
(Addis Ababa University, 2018-07) Mohammed, Seid; Shemelis, Kebede (PhD)
The production of ethanol from biomass results in the co-current production of acidic material known as distillery spent wash or vinasse. It is generated at a rate of 10 to 15 times greater than the ethanol itself, and is characterized by a high dissolved organic matter content. Anaerobic digestion is the most effective methods for the treatment of such type of wastewater. In this work, a combined adsorption–anaerobic digestion treatment of distillery wastewater was studied in order to develop an effective procedure for increasing the anaerobic biodegradability of vinasse to reduce its environmental impact. The adsorption stage with banana peel as a pretreatment was evaluated for removal of phenolic compound. The removal of phenolic compound with this biosorbent was carried out using Box-Behnken experimental design taking 3 factors, adsorbent dose, contact time, and particle size. The maximum phenol removal recorded was 76.425% at the optimum condition (adsorbent dose of 20 g/L, contact time of 129.98 min, and particle size of 0.53 mm). Removals of 22% in chemical oxygen demand (COD) was obtained in this stage. Among the adsorption isotherm models analyzed, the Langmuir model fitted best to the experimental data with maximum adsorption capacity of 4.12 mg/g, and also the adsorption mechanism follows pseudo-second order model. The pretreated vinasse was undergone to an anaerobic digestion process in the second stage under mesophilic condition. After anaerobic digestion, a global removal of 84% in COD, and over 95% in phenols content were obtained. It was shown that, a combination of treatment method (i.e. banana peel biosorption and anaerobic digestion) is a promising option for simultaneous removal of phenol and COD from molasses vinasse under the stated conditions.
Ammonium Chloride Production and Optimization of Brine Ammoniation for Lime Removal in Leather Processing
(Addis Ababa University, 2014-06) Moreda, Michael; Kaba, Tassisa (PhD)
Leather industry occupies a place of prominence in Ethiopian economy in view of its massive potential for employment, growth and export. The need of import substituting leather processing chemicals from locally available feed stocks is an urgent matter both from economic and environmental point of view. One of the chemicals used in leather processing is ammonium chloride which is a deliming agent in Beam house operation. In this study, the production of ammonium chloride from proven available urea feed stocks ammonia, carbon dioxide and from the cheapest chlorine source sodium chloride which is readily available in Ethiopia, and its use and efficiency as a deliming chemical as compared to standard ammonium chloride is analyzed. A modified Solvay process approach was adopted in search of a route to the production of ammonium chloride locally. The method involves brine purification, ammoniated brine formation, carbonation of ammoniated brine, separation of sodium bicarbonate from ammonium chloride containing mother liquor, evaporation of ammonium chloride filtrate, cooling of the evaporated ammonium chloride filtrate to crystallize, centrifugation and drying of ammonium chloride which is collected as a white solid crystal of 98.5 - 99.5 wt.% NH4Cl. This preparation met the established specification for ammonium chloride of Indian Society for Testing and Materials (ISTM). The maximum yield of ammonium chloride (92.5%) was produced when the brine ammoniation reaction was carried out at a temperature of 100C, ammonium solution to saturated brine molar ratio of 2 and reaction time of 1 hour. Therefore, these values can be considered as optimal for ammonium chloride production using ammonium solution, dry ice and saturated brine in batch reactor. The reaction temperature was varied in the range of 100C - 200C, ammonium solution to saturated brine molar ratio was varied in the range of 1 – 3; and reaction time was varied in the range of 0.5 - 1.5 hours. Testing of the optimal product on leather met the IULTCS standards.
Anaerobic Co-Digestion of Slaughterhouse Wastewater with Water Hyacinth (Ecchornia Crassipes) For Biogas Production Using Rumen Fluid as Inoculum: Characterization and Parametric Optimization
(Addis Ababa University, 2021-10) Rakeb, Kifle; Zebene, Kiflie (PhD)
The purpose of the present study was to characterize and optimize the co-digestion of Slaughterhouse wastewater with Water Hyacinth (WH) for biogas production using rumen fluid as inoculum. The slaughterhouse wastewater and water hyacinth were first characterized to determine their potential for biogas production. Water Hyacinth reducing sugar content was determined (11.94 g/L) using dinitrosalicylic acid (DNSA). Co-digestions were carried out in batch reactors. The effects of substrate composition (ratio of WH to SWW), hydraulic retention time and pH on methane production and COD removal efficiency were investigated and optimized using RSM-Optimal (custom) design. Accordingly, the optimum methane production and COD removal efficiency were found to be 76.2% and 59.1%, respectively at HRT of 40 days, a substrate composition of 50%SWW: 50%WH and a pH of 7. Furthermore, the bio-digestate was investigated for fertilizer potential. Results show its nutrient values were below the FAO suggested values. FAO suggests a minimum of 5% sum (N+P+S) for an organic fertilizer. Results show that co-digestion of SWW with WH is promising way for producing biogas and simultaneously to control the spread of WH. In addition, it is suggested to blend the bio-digestate with organic manure for enhancement of fertilizer potential.
Analysis and Optimization of Para-Xylene Production Process From Sugarcane Bagasse
(AAU, 2018-06) Brhanu, Gebreslassie; Hundessa, Dessalegn (PhD)
Lignocellulosic biomass has a great potential for biofuel and fine chemical productions. This study focused on the effective conversion of the lignocellulosic biomasses, particularly sugarcane bagasse to the most valuable aromatic hydrocarbon called Para-xylene via two-step acid-catalyzed hydrolysis, dehydration, hydrogenation, and Diels-Alder cycloaddition reaction steps. Para-xylene is one of the most important aromatic hydrocarbons, which is used for the production of purified polyethylene terephthalate (PET), in which it is used for the production of world plastics. So, the production of fine chemicals from biomass helps to reduce the dependence of the imported oils as well as used to improve the overall economic and sustainability of the world. In this study, the effect of operating variables on the Diels-Alder cycloaddition reaction between the biomass-derived furan and the suitable dienophile, which is called Maleic anhydride, was investigated and optimized using the most reactive and selective Lewis acid catalyst (AlCl 3 ). In the Diels Alder cycloaddition reaction, the effects of reactant molar ratio, catalyst loading and reaction time on the conversion of DMF and the yield of dimethyl benzoic acid was investigated and optimized using Design expert®7 software. As the result, 41.4% conversion of DMF and 64.6% yield of dimethyl benzoic acid were obtained at the optimum values of the operating variables such as molar ratio of the reactant, catalyst loading and reaction time. And also, the effects of acid concentration and reaction time on the dehydration of dimethyl benzoic acid to Para-xylene were investigated, and 70.36% conversion of dimethyl benzoic acid and 49.66% yield of Para-xylene were obtained. In addition to this, the final product (Para-xylene) was analyzed using FTIR and GC-MS. As the result, the FTIR result is the same with the standard functional group of 1,4-dimethyl benzene, and 30.88% composition of Para-xylene were obtained using GC-MS.
Analysis of Fillers for Production of Alternative Building Materials Using Magnesia Cement
(Addis Ababa University, 2008-01) Tadele, Tamrat; Assefa, Berhanu (PhD)
Fillers, which are available in the country, are essential for the production of magnesia cement boards. These include pumice and lignocellulostic fillers such as bagasse, sawdust and coffee husk. While applying these fillers to produce the boards, their nature and performance should be studied. Magnesia cement was used as binding materials; varying boards were produced for different proportion fillers with fixed ratio of magnesium oxide and magnesium chloride. For the board produced, density, water absorption, and setting time as well as mechanical properties such as the compressive strength and the bending strength determined. In addition, the effects of different fillers on the properties of the board and production cost were examined. When the saw dust and coffee husk filler substituted the current used bagasse filler, the water absorption and setting time of the boards reduced. While the density, bending strength and compressive strength of the board increased. The mix ratio of fillers and pumice powder had also influence on the physical and mechanical property of the boards. The test results showed as the proportion of the pumice increased, the mechanical strength of the boards increased and the setting time of the cement paste reduced. The cost analysis showed that the saw dust board production cost was lower than coffee husk and bagasse board cost. While the production cost of the coffee husk board was slightly higher than others. viii In aim of production of filler boards as alternative building materials are, the cost comparison showed in the possibility of producing relatively low price than the hollow concrete blocks included finishing work cost.
Application of Hydro-Metallurgy (Wet Etching) To Recovery A Precise Metal (Gold) From A Wasted Printed Circuit Broad (WPCB): Case Study of Ministry of Information Communication and Technology (MICT)
(Addis Ababa University, 2017-11) Kidist, Wendium; Berhanu, Assefa (PhD)
This thesis research is undertaken with the main objective of assessing the existing e-waste management in Ethiopia by taking ministry of information and communication technology as a case study and to propose e-waste recycling approach (hydrometallurgy) to recover gold. To meet the research objectives a blend of qualitative and quantitative methods were used where unstructured key informant interviews, Observation of the e-waste disposal site from the selected govermental organization and computer recycling and refurbishment center (CRTC) at Kality were combined with Case study at laboratory scale hydro-metallurgy to recover gold from waste printed circuit boards (PCB).It is found that E-waste is expected to be a huge problem in the future, given the rise in consumption trend of the target institutions and the general importation trend of the country. There is high accumulation of old ICT equipment in the target institutions of the study. Parallel to that, The current trend of lifecycle management of this electronic waste at CRTC and at Addis Ababa University is out date and the precious metals like that of gold are not properly recycled.in addition by applying hydrometallurgical approach (wet etching), from a sample of 500 gm printed circuit board 1.66 gm of gold was recovered with mineral composition of 99.71% Au, 0.12% Ni,0.16% Cu. this research under takes an experimental procedure where, At the start of the experiment 20 gram of fingers was used for on batch. And added to on an empty beaker. The next step will be dilution of the hydrochloric acid, hydrochloric acid with the concentration of 35% will be diluted by adding 57 ml of water on the biker. Finally we can get hydrochloric acid with the concentration of 15% with a volume of 43 ml. next the addition of hydrogen per oxide which has a concentration of 15% with a volume of 50 ml and the reaction proceeds for 6hr after that The combination of hydrochloric acid and hydrogen per oxide will detached the gold fingers from the silicon chips and a film of gold fingers will float, finally Using kitchen strainer and a large coffee filter the gold foils will be filtered out of the acid peroxide solution. The results were obtained by taking Hydrochloric acid to hydrogen per oxide proportion(1:0.5,1:0.4,1:0.9),retention time( 6hr,12hr,21hr) and hydrochloric acid concentration of ( 5%,10%,15%) as factors and on the basses of the study the optimum conditions to get a maximum amount of gold (0.2455 gm) was HCl: H 2 O 2 proportion of (1:0.5), HCl concentration (10%) and retention tine (12hr) .In conclusion, to draft a solution and act accordingly, the government through its instruments should put a system in place.
Approach Towards High Performance Water Vapour Permeability Upper Leather from Goat Skin
(Addis Ababa University, 2014-09) Mekonnen, Bekele; Muralidharan, B (PhD); Das, B.N. (PhD); John, Sundar (Mr.)
The mechanism of increasing WVP Goat upper leather, the processes have been developed. These process developed during the project were, increased percentage of bating enzyme during bating process, increased the duration time of liming process, avoided the qubracho powder and acrylic syntan during retanning process, decreasing of synthetic fat liquor and instead used semi synthetic fat liquor, increased the percentage of degreaser during degreasing process, after wet blue for 2hrs treated the leather with 1% of urea and acetic acid. For each process, the physical properties such as WVP, tensile strength, percentage elongation at break, tear strength and grain crack were carried out. The result obtained from each process at crust and finished listed in chapter 4 in table form. The experiments carried out for both control and experiments for all experiments.
Approaches to Near Zero Utilization of Water in the Post tanning Operations of Leather Processing
(AAU, 2014-09) Solomon, Fessehaye; K J., Sreeram (PhD)
Any industrial activity would generate waste, whose form would be as solid, liquid and/or gas. While industrialization is important to a nation’s economy, the wellbeing of human kind is even more important. The conflict for water between mankind consumption and industrial activity is increasing day by day as the population is increasing. An industrial activity like leather processing is a water intensive process, with most of the industries consuming 35 L of water to process every kilogram of hide/skin. While it is easy to wish away an activity like leather processing, an analysis of the relevance of this industry to Nation building would reveal that this is the only industry that uses a byproduct of meat industry, viz., skin and converts it into a fashion commodity. In the transformation, a host of rural men and women are involved directly or indirectly. For the nation, it is a good source of export income. This research work is one of an out-of-the-box thinking of systematic reduction and utilize known concepts of recycle, reduce or recovery of used water from processing. For this, the methodology has relied upon the replacement of water with environmentally benign and clean/green solvent for transporting chemicals into the skin matrix instead. The work consists of identifying the appropriate solvent or solvent mixture that a) did not have any adverse effect on the fibre structure, b) where a significant number of leather auxiliaries could be dissolved or dispersed and c) could be easily recovered and reused. The combination of solvents was selected from amongst reported clean/green solvents and the solubility / stability of the auxiliary dispersions determined by the measurement of the zeta potential of the system. The initial interaction of the dispersed auxiliaries with skin matrix being one of adsorption, various models of adsorption can be fitted to understand the nature of binding. The physical and visual properties of developed leathers have also been compared.
Assesment of Maerua Subcordata Root As Biosorbent for The Removal of Cr (Vi) Ions From Tannery Waste Water
(Addis Ababa University, 2015-05) Berecha, Mesfin; Negusie, Agizew (PhD)
Chromium containing wastes are generated by industries such as leather tannery, electroplating, paint and pigment manufacturing. The form of Cr (VI) is responsible for human carcinogen as well as water and soil pollution. The main objective of the present study was to evaluate the possibility of using Maerua Subcordata as a Biosorbent for the removal of Cr (VI) from tannery waste water and aqueous solution. The study was conducted in Addis Ababa university Environmental science laboratory center and Ethiopian leather industry development institute laboratory center, from January to May, 2015. Maerua Subcordata was collected from South Omo Zone DasenechWoreda and cut in to small pieces, dried in the sunlight and grind to produce the powder, treated with H3PO4 (45%w/w). Physical characterization such as moisture content and bulk density of activated Maerua Subcordata was done and it was found low moisture content which indicates high quality of the biosorbent.The Biosorption of Cr (VI) from aqueous solution and real tannery waste water by activated Maerua Subcordata was studied. The biosorbent was characterized by FTIR spectroscopy and characterization of the Maerua Subcordata suggested the possible contribution of carboxyl and hydroxyl groups in Cr (VI) Biosorption. The Biosorption efficiency of the Maerua Subcordata was dependent on the pH of the Cr (VI) solution, with pH 3 being optimal. The removal rate of Cr (VI) ions increased with increase in contact time and remained constant after an equilibrium time of 60 min. The removal of Cr (VI) ions increased with increase in biosorbent concentration with the optimal biosorbent dosage at 125 mg/L. Both Langmuir and Freundlich model were followed by adsorption of Cr(VI) on activated MaeruaSubcordata. But Langmuir model best describes the adsorption data with coefficient of determination (r2) value 0.993.The maximum adsorption capacity obtained from Langmuir model is 4.54mg/g.The RL value obtained from Langmuir model shows the adsorption is favorable. When applying the biosorbent to real waste water 86.5% removal efficiency was obtained. The reduction in efficiency might be due to the presence of interfering ions which compete with Cr (VI) ion for Biosorption. Therefore, the study revealed that the activated Maerua Subcordata could be used as an excellent biosorbent for the removal of Cr (VI) chromium from Tannery wastewater and aqueous solution. Key words: Hexavalent chromium, Activated Maerua Subcordata, Biosorption
Assessment and Modeling of Surface Water Quality Dynamics in Awash River basin, Ethiopia
(Addis Ababa University, 2019) Amare, Shiberu; Zebene, Kiflie (Assoc. Prof.); Agizew, Nigussie (PhD) Co-Advisor
Awash River has the most important economic values in Ethiopia. However, it has been recognized as being impaired by high amount of various pollutants owing to waste released from different socio-economic activities in its basin since the basin encompasses the main urban, industrial and agricultural centers of the nation. However, investigation of pollution level of the basin is necessary for decision makers to safeguard Awash River and its end users, which has not been addressed yet. This research was therefore aimed at evaluating the status, assessing the spatial-temporal dynamics and modeling surface water quality dynamics in relation to different land use scenarios in Awash River basin. Status of water quality of Awash River was evaluated with respect to drinking and irrigation water uses by choosing 17 sample sites along the River based on accessibility and land use severity and sampling was done twice in each of the dry and wet seasons. Then both onsite and offsite water quality analyses were undertaken following standard procedures. After comparing different water quality indices in use todate, Canadian council of ministers of environment water quality index was applied to compute the water quality indices. The drinking and irrigation water quality indices of the upper basin were 34.79 and 46.39 respectively, which were in the poor and marginal categories of the Canadian water quality ranking. Similarly, the respective indices for the middle/lower basin, which were 32.25 and 62.78, lie in the same ranges of the ranking. Although the difference in the used dataset of the two cases and natural purification in the course of the River might contribute to the difference in WQI, it is generally conceivable that the water quality of the River is below the fair rank. To assess the spatial and temporal variation of water quality in the basin, means of the 9 years’ (2005-2013) water quality dataset of 19 parameters from 10 stations in the basin were used. After validating, normalizing and checking the sampling adequacy and internal consistency of the data, principal component analysis was computed and four principal components were generated. Factor loadings, correlations between variables and the principal factors as well as between sites and the principal factors were tabulated. Agglomerative hierarchical clustering done on the dataset resulted in four clusters based on similarity of water quality characteristics. The Mann-Kendall’s two tailed trend test detected temporal trends for total hardness in February over all sites and for most parameters in the basin in the 9 years period. Spatial analysis of the 14 sampling sites of the basin showed that as one moves from upper to lower parts of the basin, electrical conductivity, total hardness and chloride levels decrease in the dry season. However, total hardness slightly increases and total dissolved solids, chloride, and sulfate content decrease in the rainy season. Cl are maximized respectively at before Beseka and Beseka in both seasons and Beseka, before Beseka and Sodere spring are found to be important sites responsible for the spatial variation. - and EC/TDS/SO4 - To see the relation between land use/land cover (LULC) and water quality in the basin, LULC dynamics was assessed by using cloud-free LS 5 and 7 TM imageries of 1994, 2000 and 2014. The images were captured from EROS center of USGS GloVis viewer and classified by supervised classification coupled with maximum likelihood algorithm in ERDAS Imagine. The dominant LULC of the eight identified land use types were agriculture, barren land, and shrubland in the 3 years’ period. Built-up and water bodies were found to have increased and decreased respectively by about 147% and 63% as one goes from 1994 to 2014. Moreover, in line with the changes in land use specifically of urbanization and agricultural intensification from 2000 to 2014, around which water quality have been analyzed, the parameters EC, TDS, Alkalinity, TH, SO4 2- , and NH3 were found to increase monotonically. Mean values of water quality indicators such as EC, nitrate, and some anions have been compared in the agriculture-dominated, industry-dominated and urban-dominated land uses. As a result, EC within the urban and industrial land uses was found to be maximized. Nitrate, on the contrary, is observed to be higher in agriculture-dominated land uses and higher concentration of anions (bicarbonates and chlorides) and hardness have been generated from urbanized areas. + - , Na + , Cl , K This study also evaluated performance of the Soil and Water Assessment Tool (SWAT) by modeling nitrate and phosphate at the basin scale. First, the model was set up using digital elevation model (DEM), climate, soil, and land use data. Thereafter, overall performance of the model was assessed by linking its outputs to the Sequential Uncertainty FItting Version 2 (SUFI2) procedure of the SWAT Calibration and Uncertainty Program (SWAT-CUP). The most sensitive parameters for the flow and nutrients were identified using t-stat and p-values from global sensitivity analysis of the SWAT-CUP. The goodness-of-fit of the monthly calibration measured by coefficient of determination (R ), Nash-Sutcliffe Efficiency (NSE), and root mean square error-observations standard deviation ratio (RSR) were respectively 0.79, 0.64 and 0.60 for flow; 0.73, 0.71 and 0.54 for nitrate and 0.77, 0.76 and 0.49 for phosphate. During validation, R 2 2 , NSE and RSR were respectively 0.81, 0.52 and 0.70 for flow; 0.68, 0.63 and 0.61 for nitrate and 0.82, 0.81 and 0.44 for phosphate. The results suggested that the model is promising to predict nutrients in the basin. From the modeling, concentrations of nutrients were found to be both seasonally and spatially variable. Sub-basins 4, 8, 13, 21 and 39 were hotspots both in 1994 and 2014 with respect to exporting higher amounts TN and TP. From the temporal investigation of nutrients’ monthly averages in the period from 1997 to 2014 of sub-basin 3, the rainy months (March, July and August) export higher amounts. Basin-wide comparison of the monthly averages of nitrate, phosphate, TN and TP losses from the model simulations with the 2000 and 2014 LU’s indicate that the respective values were generally greater in 2014 than in 2000. From the trends of TN and TP for each of the 53 sub-basins in 1994, 2000 and 2014, slight reduction was observed for the year 2000 as compared to that in 1994. However, since the increment from 2000 to 2014 was significant, the overall trend from 1994 to 2014 was found to be positive (increasing). Results of the study have applications of filling the existing knowledge gap, facilitating informed decision making, using as a customizable framework for similar studies in other river basins of the nation.
The Assessment of Peanut shell and Chat stem as Alternative Energy Source for Cement Industries
(AAU, 2018-10) Birhan, Gebregziabher; Shimelis, Kebede (PhD)
Cement industries are one of the major energy-intensive industries and heavy polluting process. To reduce the energy cost and environmental impact, cement producers are currently using alternative fuels. This study analyzed the assessment of peanut shell and chat stem as alternative energy source for cement industries. The main objective of this study was to carbonized mixed of a peanut shell and chat stem. The parameters of carbonization process, which affect the calorific value such as temperature (350, 450 and, 450 o C), time (60, 90 and 120min) and mixing ratio (25, 50 and 75%) were optimized via Central Composite Design (CCD). All the necessary analysis that included physiochemical characteristics of peanut shell and chat stem, mixed carbonized and mixed carbonized pellet, then the results were compared with commercial coal. In addition, thermogravimetric analysis were examined the thermal property of peanut shell and chat stem. Based on the result, the optimal conditions were (temperature at 450 o C, time for 60min and mixed ratio 75%) with a maximum calorific value of 6552.6 Cal/g. However, the energy content of sample was comparable with coal, but it needs pellet for suitable storage, handling, transporting. Then the optimum mixed carbonized pellet with 10% of molasses, the calorie develop to 6838.19cal/g. The optimum mixed carbonized pellet showed a decrease in moisture content (2.87%), volatile content (30.75%), Hydrogen (2.95%) and Oxygen (26.19%) while the fixed carbon (57.57%), and carbon (70.86%) increased considerably. Therefore, in this study shows that the mixed carbonized pellet has potential replaced coal as an alternative energy source for cement production due to their calorific value at optimum carbonation condition.
Assessment of Photo-Fenton Process for The Removal Of Pesticide from Wastewater
(Addis Ababa University, 2019-12) Bikila, Firdissa; Solomon, Kiros (PhD)
The main purpose of this work was to study assessment of photo-Fenton process (Fe /H2O2/UV) for the removal of pesticide from wastewater. Synthetic wastewater from 2,4Dichlorophenoxyacetic was prepared and characterized for its organic matter content and also it PH and turbidity which has a significant effect on the degradation process. Box-Benkhen design response-surface methodology was developed to optimize photo-Fenton degradation of 2,4Dichlorophenoxyacetic in which UV light radiation was used as a source of light. The three variables considered in Box-Benkhen design model included initial 2,4-Dichlorophenoxyacetic [2,4-D], hydrogen peroxide [H2O2] and Ferrous iron [Fe 2+ ] concentrations. The removal efficiency was expressed in terms of total organic carbon (TOC) and chemical oxygen demand (COD) percentage removal. The optimum values of 94.7 mg/L 2,4-D, 22.78 mg/L Fe 2+ , 156.4 mg/L H2O2 were obtained by optimizing the variables using Box-Benkhen design that the data was analyzed after carrying out each experiment for 2 hours at room temperature. The photo-Fenton process led to 85% TOC removal and 96% COD removal thereby showing the effectiveness of using photo-Fenton process for the removal of pesticide from wastewater.
Assessment of the Current Solid Waste Management Practice: A Case Study of Dukem Town, Central Oromia Region, Ethiopia
(Addis Ababa University, 2024-06) Ikram Mohammed-Amin; Shimelis Kebede
Solid waste management is recognized as a global concern that impacts both individuals and governments. Insufficient waste management practices in cities, such as widespread waste dumping in water bodies and along roads and drainage canals, exacerbate sanitation issues in African nations, Ethiopia included. Ethiopia, categorized as a lowincome country, grapples with the repercussions of ineffective management of solid waste, especially in its swiftly urbanizing areas. Dukem is one of the town located in a central Oromia region of Ethiopia facing the problem. The primary objective of this study is to evaluate the present state of solid waste management in Dukem Town. Descriptive survey and Multi-stage sampling technique was employed. The samples were collected from 90 household and from different commercial activities in the study area. The collected samples were sorted into 11 components and measured. Organic wastes represent a significant proportion of the total Solid Waste produced and accounts for about 67.34%. The remaining waste is made up of dense plastic (0.92%), film plastics (5.67%), paper and cardboard (4.08%), metals (1%), special wastes (0.36%), textiles and shoes (1.3%), glass (1.97%), composite products (0.15%) and other wastes (17.21%). According to the study's findings, Dukem Town generates 0.209 kg of solid waste per person every day with a density of 287 Kg/m3. Material flow analysis can be applied in environmental research and it was used as a basis for analyzing and planning waste management and recycling systems and also to evaluate an existing solid waste management practice of Dukem. The analysis of the socio-economic effect evaluation of solid waste management strategies also looked at how it affected the content and amount of solid waste. Due to the wastes high organic content composting is good waste management option that has to be practiced, since there will be better chance of lowering the enormous volume of waste disposed away to disposal site as well as decreasing the Greenhouse gas emission. By composting 50% of the waste designated to the disposal site 39.5% of resource will be managed.
Assessment of the Current Solid Waste Management Practice; Case Study of Bishoftu Town, East Shewa Zone of the Oromia Region, Ethiopia
(Addis Ababa University, 2024-05) Mahelet Admassu; Birhanu Assefa (PhD)
The success of waste management requires reliable data on waste generation and composition, which is critical for making decisions about the best waste management system. There is currently no data on Municipal Solid Waste (MSW) generation and composition collected in Bishoftu town. In order to provide baseline data for the establishment of a municipal solid waste management system, the primary goal of this study is to analyse the rate of generation and composition of municipal solid waste. The samples were collected from the household from 4 Keble’s and from different commercial activities like hotels, resorts, restaurants and cafeterias, open market, super market and mini markets found in the town. The collected sample was sorted out in to various components. Subsequently, the weight of each component were measured and recorded. The daily generation of MSW works out to be 0.31 Kg /day/person with a density of 306 Kg/m3.The study results reveal that the MSW stream has the largest proportion of biodegradable waste (69 %) followed by other waste (18 %) containing ash material and different solid waste types. From the socio-economic analysis, middle socioeconomic group and lower socioeconomic group generate more waste due to more family members and energy type used for cooking while socioeconomic characteristics like education level, occupation, age, gender, and housing condition have no relationship with solid waste management practices. Understanding the movement of waste in an urban area is crucial for identifying the main problems and opportunities for improvement in the efficient handling of waste. Assessment instruments like material flow analysis (MFA), a technique that is widely used in waste management research, offer an organized and objective assessment procedure to best describe the waste management system, identify its strengths and weaknesses, and suggest feasible alternatives. In order to assess the current waste management strategy used by the City of Bishoftu, this study uses material flow analysis. Due to the waste's high organic content If waste management options such as composting and recycling are implemented in the future, there is a greater possibility of reducing the amount of waste stream that is disposed of in landfills as well as lowering greenhouse gas emissions, which is a current global issue. By composting 50 % of the waste designated to the disposal site 47.9 % of resource is managed which have an increment of 78.1 % than the current SWM practice and a total reduction of 35.35 % in GHG emission.
Ayka Addis Textile Wastewater Treatment by the Fenton’s Reagent
(Addis Ababa University, 2011-06) Soresa, Mekibib; Worku, Teshome (Eng)
Treatment of wastewater is one of the biggest challenges faced by textile manufacturers. One of the textile industries in Addis Ababa at Alem Gena, Ayka addis textile and investment group plc, is experiencing high concentration of COD and color in the final effluent, due to the absence of appropriate treatment facility, as a result of this the effluent wastewater exceeds the standard discharge limits. The use of conventional textile wastewater treatment processes becomes drastically challenged to environmental engineers with increasing more and more restrictive effluent quality by water authorities. Conventional treatment such as biological treatment discharges will no longer be tolerated as 53 % of 87 colors are identified as non-biodegradable. The purpose of this study was to investigate the suitability of using Fenton’s reagent for treatment of Ayka Addis textile effluent wastewater and reduction of COD and color from the wastewater. The oxidation experiments was carried out using Fenton’s reagent (hydrogen peroxide (H2O2) and ferrous sulphate (FeSO4.7H2O)), and to adjust the pH of the wastewater sample hydrochloric acid (HCl) and sodium hydroxide (NaOH) were used. In this work, optimum conditions such pH, reaction time and stirrer speed on COD and color removal efficiency were examined and after determination of the appropriate experimental conditions, the optimum dosages of Fenton’s reagent were determined, at the optimal treatment conditions and dosages a satisfactory results were obtained. It is found that the tested Ayka Addis textile wastewater revealed high susceptibility to treatment using a combined action of ferrous salts and hydrogen peroxide. The main characters of the wastewater, such as color and chemical oxygen demand (COD) were reduced by considerable amount. The result of this investigation shows a marked increase in degradation of pollutants by Fenton’s reagent oxidation. Keywords: Fenton’s reagent, textile wastewater treatment, advanced oxidation process

Browse

Browsing School of Chemical and Bio Engineering by Title

Results Per Page

Sort Options