Biochemical Engineering

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Development of Tomato Juice and Sauce From improved Varieties
(Addis Ababa University, 2009-11) Alemu, Ayele; Tefera, Nureligne (PhD)
The favorable climatic condition, the vast irrigation sources, the abundant labor and other factors of Ethiopia are viable for the production and processing of tomato and other fruits. The present study has been initiated to evaluate the existing manufacturing process, and test the suitability of three tomato varieties for juice and sauce production. This helped to see the technological advantages for the production of good quality products. Samples products in triplicate from each variety Bergad juice (BJ1, BJ2, BJ3), Miya juice (MJ1, MJ2, MJ3), Chali juice (CJ1, CJ2, CJ3), Bergad sauce (BS1, BS2, BS3), Miya sauce (MS1, MS2, MS3), and Chali sauce (CS1, CS2, CS3) were prepared and analyzed for their physicochemical characteristics. They were determined following standard methods. Texture was analyzed according to TA-plus NEXYGEN manual. Color was determined by LOVIBOND 3000 color comparator. Titration methods by 0.1N sodium hydroxide and phenolphthalein indicator were used for the determination of acidity. Abbe type refractometer was used at a temperature of 230C for TSS. The process parameters at Merti Agro-Processing plant were evaluated to test the suitability of improved varieties. The data obtained from the laboratory analysis were subjected to ANOVA using SPSS software. Bergad (Merti Variety) was used as a control. Means were then compared at 5% significance level. The results showed that Juices of improved varieties were not significantly different from the control in acidity and color. In fact, they registered high TSS than that of the control. The Flavor of Chali juice was preferred most and was not significantly different from the control. However there is a significant difference in NTSS, Miya and Chali scoring higher means but all sauces are not significantly different in acidity. Based on the findings a tomato juice manufacturing plant has been suggested that Miya variety can be used for both juice and sauce production, while Chali can be used only for sauce production.
Chemical Engineering Department Environmental Engineering Stream Anaerobic Co-Digstion of Sewage Sludge and Abattoir Wastes to Enhance Biogas Production
(Addis Ababa University, 2010-06) Aberra, Dida; Worku, Teshome (Eng)
Concerns about the managing of sewage sludge for an ever increasing trends of sewage sludge generation coupled with the complex sludge characteristics is a big challenge for Addis Ababa Water Supply Authority. Accumulation of large volumes of dried sludge (cake) in treatment compound has become common. Since sewage sludge contains toxic pollutants and disease-causing organisms and the failure to properly manage sewage sludge may have adverse effects on human health and the environment. As a result, the city water supply authority has to search for holistic and systematic ways of managing it. In this study, a lab scale batch anaerobic co-digestion of sewage sludge and abattoir wastes under mesophilic condition for 20 days was used to digest sewage sludge taken from Kaliti dump site and reduction in volume of the wastes as a result of anaerobic digestion, production of methane and soil conditioner potential were analyzed. Abattoir wastes were co-digested with sewage sludge so as to enhance its nutrient values. 100% SS, 80%SS:20%WA and 60%SS: 40%AW mix ratio were used to analysis the biogas productivities of different mix ratios and 33.8%, 48.3% and 56.9% methane were obtained for SS alone, 80%SS:20%AW and 60%SS: 40%AW respectively. Reductions in volume of the sludge after digestion were also seen as the mix ratio increases. The obtained results are generally consistent with the data from literature where co-digestion of sewage sludge with other substrates rather than abattoir wastes were used. Key words: Biogas, Sewage sludge, abattoir waste, co-digestion XII
Experimental Investigation on Performance Characteristics and Efficiency of Electric Injera Baking Pans „(Mitad)‟
(Addis Ababa University, 2011-11) Tafere, Awash; Assefa, Abebayehu (PhD)
Enjera baking is the most energy intensive activity in Ethiopia; and preparation of enjera is rather a long process relative to other Ethiopian food. The aim of this thesis work is to investigate the performance characteristics and efficiency of the electric baking pan („mitad‟) experimentally and to prove the efficiency of improved „mitad‟ is best. Experimentation and processing of data were performed to study the energy consumption cost and ways to increase the performance of the baking pan. Thermo-physical properties were determined quasi experimentally before, during, and after baking processes of the product („Enjera‟). Initial heating up and cyclic enjera baking time with its power consumption and heat loss analysis of the system were presented for performance comparison of the baking pans. Experiments were conducted to measure temperature profile during initial heating up and cyclic baking of the pans. Maximum energy losses are occurred at the bottom of conventional and improved baking pans with the efficiency of 52% and 75% respectively. Even though the efficiency of improved electric „mitad‟ was higher than the conventional one, still there was high energy loss due to poor insulation material. Performance improvement options of each baking pans can be made by increasing the number of cycles and density of the batter. This alternative can be increase the efficiency by 5-10% of the baking pans. Economic result illustrates that improved baking pan has higher initial capital investment than the conventional one; but they have lower operating costs. Then overall present worth of improved baking pan has lower cost than conventional baking pan. Finally, based on the points outlined above, improved electric „mitad‟ have an advantage over conventional electric „mitad‟ and our recommendation is to install improved baking pans in the kitchens of the Ethiopian house hold. Key words: Experimental investigation, Thermophysical Property, Heat Transfer Analysis
Study of Domestic Solid Waste Management in Jimma Town, Southwest Ethiopia
(Addis Ababa University, 2012-10) Tadesse, Dereje; Worku, Teshome (Associate.Professor)
Optimization of Process Parameters for the Extraction of Oil from Mango Seed Kernel (Mangifera indica) for Cosmetics Application
(2015-06) Kemal, Mustefa; Yimam, Abubeker (PhD)
The main aim of the study was to determine the optimum operating condition for the extraction of oil from mango seed kernel. For this, particle size range of 0.25 mm - 0.5 mm, 0.5 mm - 1.5 mm and 1.5 mm – 3 mm, solvent type hexane, ethanol and petroleum ether and extraction time of 2 hr, 4 hr and 6 hr were considered for optimization. A general factorial design was applied to investigate the effect of process variables on oil yield. Maximum oil yield of 84.81% was obtained for particle size range of 0.25 mm - 0.5 mm at extraction time of 6 hr and with solvent type hexane followed by a yield of 83.33% at particle size range 0.25 mm - 0.5 mm, solvent type petroleum ether and 6 hour extraction time. And minimum oil yield of 18.88% was obtained for particle size range 1.5 mm – 3 mm at extraction time of 2 hr and with solvent type ethanol. ANOVA analysis was showed significant effect of particle size, solvent type and extraction time on oil yield (P value < 0.05). When the particle size range decreased from 1.5 mm – 3 mm to 0.25 mm - 0.5 mm the oil yield increased from 64.07% to 84.81% for solvent type hexane and for 6 hr extraction time. As extraction time was increased from 2 hr to 6 hr the oil yield increased from 57.41% to 84.81% for solvent type hexane and particle size range 0.25 mm - 0.5 mm. Quadratic regression model equations were obtained to describe the effect of variables on the oil yield. The physicochemical properties (total phenolic content, unsaponifiable matter, iodine value, acid value, saponification value, moisture and volatile matter, pH, viscosity, refractive index and specific gravity) of the oil extracted under optimum condition were determined and compared to those of the commercial available mango kernel oil and Indian standards for mango kernel fat. It was found that the physicochemical properties are within the standard except the acid value which is slightly higher. The result also indicated that there is a presence of high unsaponefiable matter (3.85%) and phenolic content (115mg/g for ethanol extract, 83.2mg/g hexane extract and 79.6mg/g for petroleum extract) in the mango kernel oil (obtained from local variety) which makes the oil suitable for cosmetics application. Key words: Mango seed kernel oil, Total Phenolic content, Unsaponefiable matter, Extraction
Jam Development from Selected Varieties of Mango
(Addis Ababa University, 2016-10) Endayehu, Nega; Zegeye, Adamu (Mr)
Two mango varieties namely Kent and Neohera(NE1) were subjected to analysis and jam was manufactured. Mango pulp was extracted and cooked using pan kettles, and then sugar, citric acid, commercial pectin, and sodium benzoate were added during cooking. Mango jams were packed into glass jars then stored at room temperature (30±5ºC), refrigerator (5±2ºC) and deep freezer (-18ºC) for four months. The results revealed that Kent mango had the highest pulp content (72.9%) its pulp had the highest total soluble solids (17.0°Brix), highest acidity (0.56%) and lowest pH (3.54) while NE1 Mango had high reducing sugars (2.59%) and total sugars (10.85%). Mango jams were prepared and analyzed for physicochemical, microbial and sensory parameters at 30 days storage interval for 120 days. The sensory evaluation of mango jams tested at zero time (fresh) showed that Neohera(NE1) jam was superior in color and flavor, while Kent jam was superior in consistency and overall acceptability. The organoleptic composition of the two mango jams compared to the commercial jam showed that the kent mango jams are comparable to the highest quality jam in Ethiopia and better than the other imported commercial jam. No detectable yeast, mold and negligible total viable count were observed in all mango jam samples during storage period. A statistical model was used to optimize the factor levels for highest acceptability to produce Kent mango jam. Keywords: Jam, Mango, Optimization, Production.
Characterization and Optimization of Biodiesel from Cotton Seed Oil using Ethanol with egg shell CaO
(Addis Ababa University, 2017-06) Gebreyohannes, Nigisty; Woldeyes, Belay (Professor)
The demand of world energy increases from time to time, this leads to gradual depletion of petroleum reserves, petroleum price rising and increases environmental problems. Beside to the above problems Ethiopia has additional diesel transportation cost. These all problems has motivated the search for sustainable and environment-friendly alternative renewable biofuels such as biodiesel. Since, it is non-toxic and capable of fulfilling an increasing energy demand. In this study biodiesel was produced by transesterification reaction in the presence of CaO with 99.5% ethanol. The biodiesel production process includes CSO extraction and CaO catalyst preparation from chicken egg shell waste. Moreover, this study characterizes the Physico-chemical properties of CSO and ethyl ester according ASTM D6751 standards to use the FAEE as an alternative fuel for diesel engines. All of the measured Physico-chemical properties of the biodiesel was in the range of the international standards. Design expert 7.0.0 with Box-Behnken was applied to investigate the effect of reaction parameters such as, reaction temperature (70, 75 and 80oC), ethanol to oil molar ratio (6:1, 9:1 and 12:1) and catalyst loading (1, 2 and 3%) on the yield of biodiesel. Significance of the process variables were analyzed by ANOVA. RSM was applied to investigate the interaction effect of process variables on the yield of biodiesel and to find the optimum yield. As the result of RSM optimization, the optimum yield of biodiesel 97.65 % w/w were found at an optimum reaction temperature of 73.71 oC, ethanol to oil ratio of 10.12:1 and a catalyst loading of 1.84 wt% of oil. Keywords: Cottonseed oil, Trans esterification, CaO, Biodiesel & Optimization
Utilization of Duckweed as a Carbon Source for the Production of Lactic Acid
(AAU, 2017-06) Endriss, Ali; Eduardo, Ojito (Prof.)
Despite a great deal of research work on lactic acid fermentation in the past, the production of lactic acid from duckweed has yet to be investigated. In this study lactic acid was produced from duckweed thourgh existing technologies of saccharification/acid hydrolysis and fermentation of starch would been used for duckweed-to-lactic acid conversion. For this purpose, small fronds of duckweed plants was harvested, crushed and prepared into a solution. The duckweed slurry was subjected to acid hydrolysis. Then, fermentation of duckweed hydro-lysate was done in shake flasks using Lactobacillus plantarum species which was isolated from enset. The immediate solutions were anlysed by using UV-Spectrophotometer (concentration of lactic acid) and serial dilution methocd (viable cell count). Finally, the optimum operation conditions of fermentation (i.e. incubation time, pH and temperature) were determined by using design expert software (version 10.0.1). and the optimum incubation time, pH and temprature were 21 hours, 6.4 and 34 0 C respectively. The amount of lactic acid produced and number of viable cells at optimum operating conditions of fermentations were 15.6574g/L and 4.34004E+008.
Identification, Isolation and Characterization of Suitable Lactic Acid Bacterial Strain for Minimizing Fermentation Time of Kocho
(Addis Ababa University, 2017-10) Redae, Nuguse; Adamu, Zegeye (Assoc.Prof.)
Kocho is a traditional food prepared through fermentation of decorticated Enset in Southern Ethiopia. It has been produced for many years and is being consumed in the region. Various research findings were reported on Enset with major concerns such as food safety and security issues, microbial dynamics of enset fermentation, microbial spoilage and accompanying changes, biochemical changes during fermentation and the effect of altitude on microbial successions. However, gaps were observed during Kocho fermentation, involving lactic acid bacterial (LAB) strain for traditional Kocho fermentation, standardization and optimization of the process. Kocho fermentation has been done in underground pit for a minimum of four months. This long time of fermentation has become a problem of food insecurity, and its minimization is the main concern of this thesis research. Three Kocho samples (Month-1, Months-3 and Months-6) and three Enset trial varieties (Agade, Disho and Gimbo) were taken from Morsito Wereda of SNNP, Ethiopia. The temperature and pH of fermented mass samples (Month-1, Months-3 and Months-6) were measured and recorded as 32, 27 and 290C and 4.78, 4.47 and 4.39, respectively. From each of the three samples, 1mg was taken and serial dilution was prepared, thereafter 0.1ml from each serial dilution factor was inoculated to 54 petri plates and incubated at 25, 30 and 350C temperatures. Growth of mesophilic microbes was recorded from each plate. The results showed that colony forming units of microbes were the highest in Month-1 sample at the temperature of 300C. Based on morphological structure, color and size, LAB were identified, isolated, re-cultured and purified to single strain. White, small and round structure of the strain were stored at 40C. By using Enset trial variety samples as a source of carbon, broth media were prepared according to MRS composition. 30-35 CFU of the pure strain was inoculated to each broth medium, and lactic acid concentration was determined by pH meter for 36 days with 4 days interval at 35 and 300C incubation temperatures. Generally, pH dropped down linearly for both temperatures and for the three Enset trial variety samples up to 23rd day of fermentation and became constant (~pH=4.50) at 24-28th day and reached ~pH=5.30 at 36th day for all varieties. However, pH decreased faster at 350C for all Enset trial varieties, and Disho fermentation dropped faster for eight days than others, and long-delayed from 8-16th day. The pH and temperature of the experiment corresponded with pH and temperature that were recorded during sample collection of sample Month-6. The result showed that only 24-28 days are needed to get Kocho with good texture, fl
Syrup Clarification Using Flotation System with Optimized Dosages of Phosphate and Cationic Flocculant
(AAU, 2018-05) Kuma, Nacho; Adamu, Zegeye (Ass. Prof.)
Syrup is a clarified juice evaporated to approximately 65% dry solids in a stepwise evaporation process. This concentrated syrup is needed to clarify further before the final fractionation. All Ethiopian sugar factories are designed for the production of plantation white sugar (PWS) by double sulphitation system which is the main source of an increased residual sulphur dioxide in the final product. There is a significant interest in many sugar producing countries towards producing a higher quality plantation white sugar with lower color and lower residual sulphur dioxide content. A sugar with a lower color and lower residual sulphur dioxide values is achieved by replacing the syrup sulfitation process with syrup phosphatation and flocculation. The study was conducted to optimize the syrup clarification as the result of the effect of Talodura and Phosphate on reducing color, turbidity and viscosity using flotation system and there by modifying or reducing the sulfate content in the sugar. This increased sulfate is due to syrup double salfitation during syrup clarification at Wonji Sugar Factory. Since degree of clarification is dependent on the dose of Phosphate and Talodura flocculant, optimization of the doses was carried out against color, turbidity and reduction of viscosity. Design Expert 7 and JMP13 software were used to determine the common optimum doses. The range of levels of the P 2 O 5 used was 117.8 - 680 mg/L, and that of the Talodura was 7.2 - 12.8 mg/L. The optimum levels, 668 mg/L of P 2 O 5 and 12 mg/L of Talodura gave color and turbidity values of 9772 and 4669 ICUMSA respectively and a viscosity reduction of 39 %. Practicing the above optimum conditions at Wonji Sugar Factory could increase productivity and sugar quality.
Bioaccumulation of Cr(VI) from Tannery Wastewater Using Saccharomyces Cerevisiae
(Addis Ababa University, 2018-06) Tessafa, Abrham; Shegaw, Ahmed (Assoc.Prof.)
Chrome tanning is the most and widely used types of tanning process and the wastewater generated by these industries is a major source of chromium pollution in the form of Cr(III)&Cr(VI) which are released into the environment either after treated inefficiently or with no treatment and become a cause for many human health problem. Several researchers have published papers to find the solution for removal of Cr(VI) but at its low concentration and this research work investigates at high concentration of Cr(VI). Cell suspensions of S.cerevisiae at its exponential growth phase were added to 250ml plastic flasks of containing 50ml of YPD media at pH value of (3,5&8), initial Cr(VI) concentration of (5, 50&100mg/ml) and incubation time of(3,5&7 days) and shaken at 200rpm an from tannery wastewater using S.cerevisiae shows good result after Cr(VI)-contaminated wastewater has been treated at different treatment variables of pH, initial Cr(VI) concentration. Cr(VI) uptake efficiency of S.cerevisiae increases at low values of pH, Cr(VI) and incubation time and decreases at high values of these variables. And it can be conclude that Cr(VI)uptake efficiency is better at low values of the variables and the optimum conditions obtained by using the full factorial experimental design are pH value of 4.5, Cr(VI)concentration of 5mg/ml and incubation time of 5 days resulting 84.25 % theoretical Cr(VI) uptake efficiency . Cell viability test assay of this work shows the possibility of Cr (VI) removal at its high concentration using living cells that are tolerant to high concentration though the efficiency decreases as concentration increases due to inhibition. Bioaccumulation of Cr(VI) by the cell S.cerevisiae is analyzed by FTIR by comparing their IR spectrum of functional groups of the Cr(VI) free and Cr(VI) loaded S.cerevisiae cell wall that showed change of wavenumbers of biocomponents of cell wall of the two cells which confirms the binding of chromium ion with the functional groups of cell wall of S.cerevisiae and produces Cr complex compounds /precipitates. Freundlic equilibrium and pseudo second order kinetic model are used for expressing
io butanol Production from Brewery’s Spent Grain Hydrolysate by Clostridium/Eubacterium and Bacillus subtilis
(Addis Ababa University, 2018-06) Meron, Asteraye; Solomon, Kiros (PhD)
Butanol (butyl alcohol or n-butanol) is a four carbon straight chained alcohol which can be used as a liquid transportation biofuel. The objective of this study was production of bio butanol from brewery spent grain (BSG) which in effects to minimize energy cost and substituting nonrenewable energy by using renewable resources. The chemical and proximate compositions analysis was investigated. The moisture, ash, extractives, hemicellulose, lignin and cellulose contents were, 64.65, 4.2, 33.28, 17.79 and 17.87 wt. % respectively. The conversion of BSG to bio butanol can be achieved mainly by four process steps,pre-treatment, hydrolysis (dilute acid hydrolysis), fermentation and separation. Dilute acid hydrolysis was employed, because it is easy and productive process. Fermentation of the hydrolyzate was performed using 10 % v/v Clostridium/Eubacterium at 37 C temperature, pH 6.5 and 96 hr fermentation time for all samples. The experiment was designed by Box-Behnken Design (BBD) using Design expert 7.0.0 software with three factors to investigate the effect of (temperature, reaction time and acid concentration). Hydrolysis temperature was varied from 115°C to 135℃, reaction time was varied from 30 to 40 minutes and the acid concentration was varied from 1.5% to 2%. Significance of the process variables were analyzed using analysis of variance (ANOVA) and the quadratic model was fitted to the experimental results. Thus, the influence of all experimental variables, factors and interaction effects on the response was investigated. Among the investigated components hydrolysis temperature, reaction time, acid concentration, interaction between temperature and reaction time, interaction between temperature and acid concentration contributed a significant effect on the yield of bio butanol. As the result of RSM optimization, the best yield of total reducing sugar (TRS) and bio butanol were found at 127.42 0 C hydrolysis temperature, 34.32min reaction time and 1.65% w/w acid concentration. Under these conditions, 59.0 g/L total reducing sugar (TRS), 10.93 g/L biobutanol yield and 0.11 g/L.h of productivity were obtained. The optimized process variables were farther enhanced by co culturing Clostridium/Eubacterium and Bacillus subtilis. Different inoculum concentration ratios (10:1%, 10:3%, and 10:5% v/v) of Clostridium/Eubacterium to Bacillus subtilis) were used to ferment BSG hydrolysate. The results exhibited that the inoculum size of 10% Clostridium/Eubacterium with 1% Bacillus subtilis maximised the production of biobutanol to 13.76g/L and 0.14 g/L.h productivity.
Optimization of Parameters to Improve the Strength of Concrete Cube Using Bacteria Species
(AAU, 2018-06) Eman, Negash; Solomon, Kiros (PhD)
Concrete is the most commonly used building material, but the cracks in concrete create problem it was main reason for a decreased service life of concrete structures. Most research done used chemical method which not effective on cost and environmental. So, need of a new technology to overcome the bottle necking of concrete has led to the development of a very special concrete known as Bacterial Concrete. The objective of this thesis was optimizing of parameters to improve the strength of concrete using bacteria bacillus species (Bacillus subitilis, Sporosarcina pasteurii and Bacillus cibi) self-healing method. Proceed was the bacterial strains were obtained from Ethiopia Biodiversity Institute and for each bacterial growth in nutrient broth solution for 24-72 hour. Secondly, according to the mixing design twenty seven concrete mixes for each day and for each bacterial at C25 grades of concrete using water cement ratio 0.58, 0.53 and 0.45 and cement, fine aggregate and course aggregate contents of 360 kg / m 3, 800 kg / m 3 and 1087.5 kg / m 3 were prepared, respectively and tested in 7, 14 and 28 day. Significance of the process variables were analyzed using analysis of variance (ANOVA). Thus, the influence of all experimental variables, factors and interaction effects on the response was investigated. Dosage, time, water/cement ratio and in the case of bacteria Bacillus cibi use interaction between dosage and water cement ratio have significance effect on the compressive strength. As the result of RSM optimization, the best compressive strength were found on the 0.45 water cement ratio, 40 ml of dosage and the time after 14day. Also from the three bacterial Sporosarcina pasteurii selectable or give high compressive strength.
Production of Bioethanol from Brewery Spent Grain Using Cellulase Enzyme Hydrolysis
(Addis Ababa University, 2018-07) Emru, Yidnekew; Eduardo, Ojito (Prof.)
Bioethanol is a clear, colorless and mobile flammable liquid chemical compound with acceptable odour, and produced from biomass feed stocks through fermentation. The objective of this study was production of bioethanol from Barley spent grain by using cellulase enzyme hydrolysis. Decreasing of world petroleum reserves, fluctuation of petroleum price and environmental concerns, low yield cellulose acid hydrolysis and formation of inhibitory were the problem statement. Enzymatic hydrolysis method was used for cellulose hydrolysis, producing monomeric C6 sugars (glucose); enzymatic hydrolysis is more specific and high conversion rates can be achieved in long reaction times obtaining very high yields. Raw material characterization of BSG were, hemicelluloses content 28.4 %, cellulose content 27 %, and dry matter content 98.2 %. The aim of pretreatment is to disrupt recalcitrant structures of cellulosic biomass to make cellulose more accessible to the enzymes that convert carbohydrate polymers into fermentable sugars. The pretreated feedstock was mixed with 1.25 % (v/v) sulfuric acid solutions with a liquid-to-solid ratio of 20 %( w/w) and it was occurred on the temperature 121 ºC and time of 17 min, the severity factor coefficient was 0.198. Cellulase enzyme was produced from BSG using bacillus subtilus, under liquid state fermentation for 5 days at temperature of 37 ºC with pH of 5.0, in controlled incubator. For the enzyme hydrolysis, 26 full factorial central composite design (CCD) was applied to investigate the effect of temperature (40-50 ºC), pH (4.0-5.0), reaction time (24-72 hr.) and enzyme loading (1-2 %) using Design expert® 6 software. RSM was applied to investigate the interaction effect of hydrolysis process variables on the yield of ethanol from BSG. After hydrolysis process sugar content of the hydrolysate was quantified using spectrophotometer measuring its absorbance. Fermentation of the hydrolysate were performed 2.5 % Saccharomyces cerevisiae and 2.5 % fusarium oxysporum at 30 ºC temperature, pH 5.0 and 72 hr. fermentation time for all samples. Significance of the process variables were analyzed using analysis of variance. As the result of RSM optimization, the best yield of TRS was found at 40 ºC hydrolysis temperature, 4.5 PH, 48 hr. reaction time and 1.5 % v/v enzyme loading. Under these condition 96.55 %w/w and 53.68 % per 6.58 g dry barley spent grain of TRS and bio-ethanol respectively obtained.
Characterization and Treatment of Beseka Lake Water Quality Using Microbes to reduce Total Dissolved Solid (TDS) and Alkalinity
(Addis Ababa University, 2018-07) Yasin, Ahmed; Solomon, Kiros (PhD)
Water is one of the natural resource that used for irrigation, industrial, sanitation and other purpose that facilitate human activity. Lake Beseka is volcanically dammed, endorheic lake, which is located to the East direction, situated around 200 km from Addis Ababa, the capital city of Ethiopia. The Lake water is saline and alkaline with high concentration of fluoride so that the water could not be used for drinking and irrigation purpose. Different infrastructures such as a health center, high school, youth center, offices and others were affected by the lake flooding. So, this lake needs to be treatment. In present study, biological neutralization of saline- alkaline beseka lake water in the presence of glucose (carbohydrate) as carbon source was studied. To do so, determination of physiochemical characteristics of the lake water, which was pH, EC, TDS, HCO3 - , total alkalinity, chloride and fluoride were measured and also isolation of bacteria were carried out. In this study Bacillus alkalophilus bacteria was also used to compare its treatment performance with isolate (T1). Treatments of lake water sample at different pH, incubation time and inoculum size were monitored. Maximum removal of total alkalinity and TDS (Total Dissolved Solid) were observed at pH, incubation time and inoculum size of 9,72hr and 32ml respectively. Which is resulted in removal of total alkalinity; 774.669mg/l and TDS;1939.92mg/l for isolated (T1) and total alkalinity;779.631mg/l and TDS;1944.97mg/l for Bacillus alkalophilus from original value. Based on these findings, isolated (T1) bacteria were shown to be have good performance for biological treatment of beseka lake.
Extraction of Lectin from Banana Using Acid Solvent
(Addis Ababa University, 2018-11) Fatuma, Abiyu; Shimeles, Admasu (PhD)
Banana is a major tropical fruit crop distributed in more than 120 countries with an annual production of 102 million tones. Banana Lectin is a lectin from the jacalin-related lectin family isolated from the fruit of the bananas (Musa acuminate). It exists as a homodimer which are two identical kda (kilodalton) sub unit. The objective of the thesis was extraction of lectin from banana for glycoconjugates. A number of literatures were reviewed for extraction of lectin.Lectin was extracted from ripen and unripen banana. The protein was highly stable and binds to a certain carbohydrate structure. These heterogeneous class of carbohydrate-binding proteins or glycoproteins of non-immune origin are capable of specific recognition of, and reversible binding to, carbohydrates without altering their covalent structure. The maximum amount of lectin (3.6 mg) was found from ripen banana that socked in neutral pH, at 25 o C and 24 hours. And it was checked its glycoconjugates activity using KHB kit and agglutination was observed on the wall of the plate. As socking time increased from 12-36 hours the amount of lectin decreased. Large amount of lectin was observed in neutral pH than in acidic and basic solutions. Besides as temperature increased from 2530 o C, still amount of lectin decreased. This was due to the break-down of protein molecules in long socking time, acidic and basic solutions and high temperature.
Determine the Potency of Caffeine Degradation Microbes and Process Optimization
(Addis Ababa University, 2019-06) Zeynu, Shamil; Cespedes, Eduardo Ojito (Prof.)
Bioremediation being a problem solver for many different environmental and other major hazards, they play an important and cost effective role in the decaffeination process. Form collected environmental sample coffee husk. From CH caffeine can be eliminated. With this experimental work take two spp of microorganism that were bacillus subtilis and rhizobium from Ethiopia bio diversity institute, that can be capability of improving soil fertility. Could grow on the medium supplemented with 2.5g/L caffeine and could effectively degrade 2.5 g/L of caffeine in the liquid media as a sole source of carbon and nitrogen. Morphological and biochemical characteristics were maintained for re-affirmation the organism as bacillus subtilis and rhizobium. The degradation of caffeine capability was authenticated by growth curve. The next task were that those authenticated caffeine degrading bacteria applicable for conserving soil fertility by means of N-fix and p- solubilized potential then propagation and growth of those selective caffeine degrading bacteria was maintained by selective medium with and without supplement of 2.5g/l caffeine then optimized the factors that affecting cell growth with prepared broth with and without supplement of caffeine and determined interaction of each factor from experiment design software 6.0.8) the result would be temp; 35 o c, pH 7.07 incubation time 36hr from those optimal condition obtained maximum cell growth in number was 3.41995E+008 and 5.0707E+008 with and without caffeine respectively for bacillus subtilis and temp 34 o c, pH 6.6 and incubation time 28hrs optimum condition maximum cell growth 3.51146E+008 and 4.09131E+008 was obtained for rhizobium sp. of organism. That viable cell grown microorganism ready for applicable of as liquid bio fertilizer those were easiest way of production, handle, cost effective and keep soil health care method of production.
Optimization of Drying Parameters for “Moisture Reduced Teff Injera Making” Using Response Surface Methodology
(Addis Ababa University, 2019-06) Dessalegn, Abit; Eduardo Ojito, Cespedes (Prof.)
Teff Injera is the staple Ethiopian fermented bread processed from fermented tef [Eragrostis tef (Zucc.) Trotter] grain flour.” Dirkosh” is the Amharic name given to the dried /moisture reduced injera. The current potential need of the super food, Teff and its products like injera and its dried form, Dirkosh needs a scientific research that will increase its quality, healthy and market demand. Therefore, the objective of the study was to prepare and optimize the drying parameters of Dirkosh using computer controlled tray dryer. The selected drying parameters were (drying air temperature, air velocity and sample loading density) in response of the most quality parameters of the final dried injera/Dirkosh. The response variables were the final moisture content, drying time, color, texture, overall acceptability, water activity and drying rate. The optimization process done by using Box-Behnken Design, response surface methodology (RSM). Drying process factors ( (drying air temperature(55-65 C), air velocity(0.5-1.5m/s) and sample loading density(12kg/m o 2 )) were considered and made 15 experimental runs of Dirkosh drying including 3 replicates using RSM. The investigated responses were final moisture content(5.43), color(6.02), texture(6.23), overall acceptability(6.05), water activity(0.274) but drying time and drying rate were not significant model terms but it was possible to estimate the drying kinetics using the better drying process parameters. RSM with Box-Behnken Design was used to develop and optimize drying process factors in response of the dried injera. Moreover, both numerical and graphical optimizations were carried out to determine the optimum values of Dirkosh in terms significant model terms. The optimum process factors of drying process parameters were drying air temperature of 55 with a desirability of 0.65. The study showed that all the drying process factors were important parameters influencing the physicochemical and sensory qualities of Dirkosh.
Treatment of Waste Water Effluent from Coffee Industry using Anaerobic Mixed Culture Pseudomonas Florescence and Escherichia Coli Bacteria and with Gypsum: A Case in Dilla- Ethiopia
(Addis Ababa University, 2019-06) Fitsum, Ashenafi; Cespedes, Eduardo Ojito (Prof.)
Coffee processing industries generate huge amount of wastewater. The effluent is characterized by a lot of sludge, high amount of organic load and acidic nature due to fermentation process. Due to this, it contains high value of COD, BOD, TS and other contaminants. This effluent when disposed in natural water, it contaminates aquatic animals and plants environment. So, care has to be taken to ensure the quality of the releasing waters should be reduced below the prescribed standards. There are many physical and chemical treatment methods available for the removal of pollutants but all these methods have problems associated with secondary effluent, hazardous and harmful end products, high energy consuming, non-economic etc. These problems can be overcome by the use of biological treatment methods which are simple, eco-friendly and efficient where complete removal of the pollutants is possible. Cognizant of this, the researcher was initiated to study the treatment of wastewater effluent from coffee industry in the specific area by using anaerobic Pseudomonas florescence and Escherichia coli bacteria as mixed culture and with gypsum (CaSO4.2H2O). In this study, the wastewater value of BOD5, COD, TS and neutralization of the PH reduction was achieved. The results show that the treatment reduced BOD5, COD and TS from its initial concentration of 320.26 mg/l, 1261 mg/l, and 3545 mg/l to 35.66 mg/l, 97 mg/l and 68 mg/l respectively. The treatment in the study shows 87.74% reduced of BOD5 load, 92.02% reduced of COD and 98.01% reduced of TS from the initial load using optimization of the treatment method. Therefore, it can be concluded that mixed culture bacteria of Pseudomonas florescence and Escherichia coli in combination with gypsum as a new effective treatment having potential for BOD5, COD and TS reduce from the effluent treated. The mixed culture of microorganisms is capable to reduce the contaminants that made the approach cost effective, time saving compared with other results found by other authors without mixed culture. The microorganisms included in the study can be applied for the treatment of effluents containing the multiple contaminants.
Utilization of Coffee Husk as A Substrate for Vinegar Production Using Acetobacter Aceti Bacteria
(Addis Ababa University, 2019-06) Piniel, Belachew; Anuradha, Jabasingh (PhD)
Advancement in industrial biotechnology offer potential opportunities for the economic utilization of agro-industrial residues. Coffee husk is a fibrous by-product obtained during the processing of coffee cherries by dry process. These wastes cause pollution to the environment, unless treated properly. This study employs coffee husk as a substrate to produce acetic acid using acetobacter aceti bacteria in a submerged fermentation process. Vinegar was formulated after the production of acetic acid from coffee husk. Three factors; temperature, ethanol concentration and time were optimized by conducting 17 experiments according to the Design Expert Software 11, using the response surface methodology. The optimum acetic acid concentration (16.59%) was found at 33.76 ℃, 7.84% (ethanol concentration), and 68h respectively and this was analyzed using High Performance Liquid Chromatography (HPLC) followed by the formulation of vinegar to 5% acetic acid.

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