Kenya Industrial Research and Development Institute KIRDI

Nairobi, Kenya

Kenya Industrial Research and Development Institute KIRDI

Nairobi, Kenya
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Mwasiagi J.I.,Bahir Dar University | Mwasiagi J.I.,Moi University | Mwasiagi J.I.,Donghua University | Yu C.W.,Donghua University | And 4 more authors.
Fibres and Textiles in Eastern Europe | Year: 2014

Hibiscus sabdariffa L. (roselle) is grown in Kenya for its flower and calyx, which are used in the beverage industry. Roselle bast fibre has, however, not been commercially exploited. After harvesting the flowers and calyx the stem together with the bark is used as firewood. This paper reports the characteristics of bast fibres in Hibiscus sabdariffa L. (roselle) grown in Kenya. The bast fibre was characterised by studying its physical and chemical characteristics. The physical characteristics investigated included tensile properties, fineness and surface morphology. An investigation into the type of chemical ingredients present in the fibre was also undertaken. The data obtained in this study indicated that the roselle plant grown in Kenya can produce bast fibres of comparable properties to the kenaf grown in Asian countries. © 2014, Institute of Biopolymers and Chemical Fibres. All rights Reserved.

Mburu A.W.,Moi University | Mburu A.W.,Kenya Industrial Research and Development Institute KIRDI | Mwasiagi J.I.,Moi University | Mwasiagi J.I.,Bahir Dar University | Anino E.O.,University of Eldoret
Journal of the Textile Institute | Year: 2015

This study was conducted to establish optimal temperature, pH and incubation time for bacteria from gin trash, for enhancing wax removal during cotton bioscouring. Universal Rotatable Experimental Design was used for the process of optimisation and efficiency assessed by the percentage weight loss after solvent extraction of the treated fibres. Optimum wax of 0.765% out of 1.2% present in the fibres was removed at 45 °C, pH 8 within 1 h. Minitab 15 and Monte Carlos were used for the parameter modelling and sensitivity analysis. A second-order polynomial regression model was fitted and found adequate with a determination coefficient, R2, of 0.94032 (p < 0.005). At 45 °C, pH 8, maximum 0.747% wax was removed by the bacteria in pectinase treatment within 1 h. 0.752% wax was removed from bulkier treated fibres, without significant change in fibre strength. Temperature was found to be the most significant variable in the bacterial cotton wax removal. © 2015 The Textile Institute

Oloibiri V.,Ghent University | Oloibiri V.,Kenya Industrial Research and Development Institute KIRDI | Ufomba I.,Ghent University | Chys M.,Ghent University | And 3 more authors.
Waste Management | Year: 2015

The present work investigates the potential of coagulation-flocculation and ozonation to pretreat biologically stabilized landfill leachate before granular activated carbon (GAC) adsorption. Both iron (III) chloride (FeCl3) and polyaluminium chloride (PACl) are investigated as coagulants. Better organic matter removal is observed when leachate was treated with FeCl3. At a dose of 1mg FeCl3/mg CODo (CODo: initial COD content), the COD and α254 removal was 66% and 88%, respectively. Dosing 1mg PACl/mg CODo resulted in 44% COD and 72% α254 removal. The settle-ability of sludge generated by PACl leveled off at 252mL/g, while a better settle-ability of 154mL/g was obtained for FeCl3 after dosing 1mg coagulant/mg CODo. For ozonation, the percentage of COD and α254 removal increased as the initial COD concentration decreased. Respectively 44% COD and 77% α254 removal was observed at 112mg COD/L compared to 5% COD and 26% α254 removal at 1846mg COD/L. Subsequent activated carbon adsorption of ozonated, coagulated and untreated leachate resulted in 77%, 53% and 8% total COD removal after treatment of 6 bed volumes. Clearly showing the benefit of treating the leachate before GAC adsorption. Mathematical modeling of the experimental GAC adsorption data with Thomas and Yoon-Nelson models show that ozonation increases the adsorption capacity and breakthrough time of GAC by a factor of 2.5 compared to coagulation-flocculation. © 2015 Elsevier Ltd.

Were F.H.,Kenya Industrial Research and Development Institute KIRDI | Moturi M.C.,Kenya Industrial Research and Development Institute KIRDI | Gottesfeld P.,Occupational Knowledge International | Wafula G.A.,University of Nairobi | And 2 more authors.
Journal of Occupational and Environmental Hygiene | Year: 2014

The study evaluated airborne exposures and blood lead (BPb) levels in 233 production workers at six diverse industrial plants in Kenya. Blood and personal breathing zone air samples were collected and analyzed for lead (Pb) using atomic absorption spectroscopy. Blood pressure (BP) levels were measured using a standard mercury sphygmomanometer. The results indicated mean airborne Pb levels ± standard deviation (SD) as follows: 183.2 ± 53.6 μg/m3 in battery recycling, 133.5 ± 39.6 μg/m3 in battery manufacturing, 126.2 ± 39.9 μg/m3 in scrap metal welding, 76.3 ± 33.2 μg/m3 in paint manufacturing, 27.3 ± 12.1 μg/m3 in a leather manufacturing, and 5.5 ± 3.6 μg/m3 in a pharmaceutical plant. The mean airborne Pb levels exceeded the U.S. Occupational Safety and Health Administration (OSHA) 8-hr time-weighted average (TWA) permissible exposure limit (PEL) for Pb of 50 μg/m3 in the battery manufacturing, battery recycling, welding, and paint manufacturing plants. Similarly, mean BPb concentrations exceeded the American Conference of Governmental Industrial Hygienists (ACGIH®) biological exposure index (BEI) for Pb of 30 μg/dl. A significant positive association was observed between BPb and breathing zone air Pb (R2 = 0.73, P < 0.001). Approximately 30% of the production workers (N = 233) were in the hypertensive range with an average systolic and diastolic blood pressure (BP) of 134.7 ± 12.7 mmHg and 86.4 ± 8.9 mmHg, respectively. In the multivariate regression analysis, age, duration of work, airborne Pb and BPb levels were significantly associated (P < 0.05) with a change in BP. We recommend improved engineering controls, work practices, and personal hygiene to reduce Pb exposures. In addition, workers should undergo comprehensive medical surveillance to include BPb and BP testing, and airborne Pb assessments in all industries with significant lead exposures. © 2014 JOEH, LLC.

Kosambo-Ayoo L.M.,Kenya Industrial Research and Development Institute KIRDI | Bader M.,University of Hamburg | Loerz H.,University of Hamburg | Becker D.,University of Hamburg
African Journal of Biotechnology | Year: 2011

Sorghum (Sorghum bicolor (L.) Moench) is an important food and fodder crop. Fungal diseases such as anthracnose caused by Colletotrichum sublineolum reduce sorghum yields. Genetic transformation can be used to confer tolerance to plant diseases such as anthracnose. The tolerance can be developed by introducing genes encoding proteins such as chitinases and chitosanases that hydrolyse fungal cell wall. Chitinases endolytically hydrolyse the β-1,4-linkages of chitin whereas, chitosanases hydrolyse the β-1,4-linkages between N-acetyl-D-glucosamine and D-glucosamine residues in a partially acetylated chitin polymer. Particle bombardment was used to genetically transform a sorghum genotype, KAT 412, with chitinase (harchit) and chitosanase (harcho) genes isolated from Trichoderma harzianum. Transgenic sorghum plants, KOSA-1-3, that expressed the two anti-fungal genes were developed. Expression of harchit and harcho in the transformants was confirmed by quantitative real time PCR. In planta and ex planta C. sublineolum infection assays were carried out using one-week old seedlings to determine tolerance to anthracnose. Seedlings from a transgenic line, KOSA-1, were found to be significantly more tolerant to anthracnose than the parent wild type, KAT 412. The Transgenic line was further compared with other wild type sorghum cultivars. The comparison revealed a genotypedependent difference in anthracnose response. The Transgenic line KOSA-1 was found to be more tolerant than the sorghum line SDSH 513 but less tolerant than KAT L5. This demonstrated the existence of genetic diversity, which together with the transgenes, could be utilised to pyramid genes for higher tolerance to anthracnose. The two antifungal genes introduced into sorghum genome could be introgressed into other sorghum lines for fungal diseases resistance. © 2011 Academic Journals.

Were F.H.,University of Nairobi | Kamau G.N.,University of Nairobi | Shiundu P.M.,University of Nairobi | Wafula G.A.,University of Nairobi | Moturi C.M.,Kenya Industrial Research and Development Institute KIRDI
Journal of Occupational and Environmental Hygiene | Year: 2012

The concentration of airborne and blood lead (Pb) was assessed in a Pb acid battery recycling plant and in a Pb acid battery manufacturing plant in Kenya. In the recycling plant, full-shift area samples taken across 5 days in several production sections showed a mean value±standard deviation (SD) of 427 ± 124 μg/m 3, while area samples in the office area had a mean ± SD of 59.2 ± 22.7 μg/m 3. In the battery manufacturing plant, full-shift area samples taken across 5 days in several production areas showed a mean value ± SD of 349 ± 107 μg/m 3, while area samples in the office area had a mean ± SD of 55.2 ± 33.2 μg/m 3. All these mean values exceed the U.S. Occupational Safety and Health Administration's permissible exposure limit of 50 μg/m 3 as an 8-hr time-weighted average. In the battery recycling plant, production workers had a mean blood Pb level ± SD of 62.2 ± 12.7 μg/dL, and office workers had a mean blood Pb level ± SD of 43.4 ± 6.6 μg/dL. In the battery manufacturing plant, production workers had a mean blood Pb level ± SD of 59.5 ± 10.1 μg/dL, and office workers had a mean blood Pb level ± SD of 41.6 ± 7.4 μg/dL. All the measured blood Pb levels exceeded 30 μg/dL, which is the maximum blood Pb level recommended by the ACGIHR ®. Observations made in these facilities revealed numerous sources of Pb exposure due to inadequacies in engineering controls, work practices, respirator use, and personal hygiene.

Ogeya M.C.,Kenya Industrial Research and Development Institute KIRDI | Coatanea E.,Aalto University | Medyna G.,Aalto University
Proceedings of the International Conference on Engineering Design, ICED | Year: 2013

This article introduces a design approach integrating early design phase and model based engineering in order to develop innovative biomass gasifier system for rural communities in Africa. The need for such a systemic perspective is imposed by the imbrication of technical, ecological and cultural issues that cannot be ignored while designing new technology. The article proposes an integrated generic design theory approaches to discover and rank by order of importance system's variables and to single out most desired design parameters. A pre-design user requirement assessment was carried out to identify detailed stove's functions. Causal-ordering diagrams sketched for system's modelling. System functions were described graphically and synthesized through simple linear algebraic matrices. Contradictions in system functions were solved using Theory of Inventive Thinking (TRIZ 40). And system's optimization was done through simple Taguchi experimentation method. A two level L8 degree of freedom Taguchi table was used in the experimentation and optimization of the pyrolitic stove. The design approach was exemplified using the case of the "AKIBA" biomass stove.

Kelvin K.,Kenya Industrial Research and Development Institute KIRDI | Tole M.,Pwani University
Water, Air, and Soil Pollution | Year: 2011

Constructed wetlands have recently received considerable attention as low cost and efficient means of cleaning up many different types of wastewaters at secondary and tertiary levels. This is an environmentally sound method of wastewater treatment that does not use hazardous chemicals, and is based on the high productivity and nutrient removal capability of the wetland that strongly relies on its intricate ecosystem structure and function. Research work was conducted on a tropical constructed wetland to establish its capability to treat wastewater during the dry season. A comparison of its efficacy with that of conventional wastewater treatment plants was made on the basis of the measured water quality parameters. Temperature, pH, dissolved oxygen, and conductivity were measured in situ. Total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphorus, ammonia, and nitrites were analyzed in the laboratory. Fecal coliforms were enumerated and Escherichia coli counts were determined. The TSS values reduced from a mean of 102 mg/l at the influent point to 16 mg/l at the effluent point, depicting a reduction of 84.3%. Influent TDS averaged 847 mg/l, while the effluent averaged 783 mg/l. Dry season BOD5 levels were reduced from an average of 286 at the inlet point to 11 mg/l at the outlet representing a reduction efficiency of 96.2%. COD levels were reduced from a mean of 2,002.5 to 47.5 mg/l depicting a removal efficiency of 97.6%. Phosphorus was reduced from a mean of 14 to 11 mg/l representing a percentage removal of 21.4%. Levels of ammonia reduced from a mean of 61 at the influent point to 36 mg/l at the effluent point representing a percent reduction of 41.0%. There was a 99.99% reduction for both the fecal coliforms and E. coli counts. Conductivity of wastewater increased from 1.08 to 1.98 mS, while the pH increased from 6.23 at the inlet point to 7.99 at the outlet of the system. Temperature and dissolved oxygen measurements showed a diurnal variation. The dry season wastewater heavy metal concentrations were in the following ranges: Pb (0.7-6.9 ppm), Cr (0.2-0.5 ppm), Zn (0.1-2.3 ppm), Ni (0.1-1.3 ppm) with Cd and Cu not being detected in the wastewater streams. Overall, tropical constructed wetlands are effective in treating wastewater streams and they perform a lot better than the popularly used waste stabilization ponds. This paper recommends that they can be widely used within the tropics. © 2010 Springer Science+Business Media B.V.

Nalyanya K.M.,Egerton University | Migunde O.P.,Egerton University | Ngumbu R.G.,Egerton University | Onyuka A.,Kenya Industrial Research and Development Institute KIRDI | Rop R.K.,Egerton University
Journal of Thermal Analysis and Calorimetry | Year: 2016

The wide range of applications of collagen-based materials has triggered research interest especially on the effect of environmental factors in that these materials are exposed to during processing and application. As the applications of these collagenous materials continue to increase such as in the field of medicine, more studies are required to gain more insight into their properties. Collagen is a natural biopolymer whose structure is sensitive to ultraviolet (UV) radiations, which alters its mechanical properties. In this study, the influence of artificial UV irradiations, wavelength 254 nm, on the viscoelastic properties and dynamic viscosity of both pickled and tanned hide was investigated by dynamic mechanical analysis. The influence of tanning on the viscoelastic properties and dynamic viscosity was also investigated. Freshly flayed bovine hide was conventionally prepared to pickling stage and split into two identical halves along the backline. One half was tanned using chromium sulfate, while the other half was left at the pickled stage. Samples of appropriate dimensions from both the pickled and tanned hides were cut and irradiated with artificial UV light for different time duration of 6-30 h. The irradiated samples were then analyzed using the DMA in the multi-frequency mode. It was found that irradiation caused an increase in the storage modulus (E′) of pickled hide over the entire irradiation of 6 h followed by consistent decrease up to a duration of 30 h. Tanning caused an increase in tanδ that consistently decreased with the increase in the duration of irradiation. In addition, UV irradiation caused an increase in dynamic viscosity of pickled hide, but a decrease in tanned hide. The results show the predominant elastic nature of bovine hides as indicated by tanδ magnitudes less than a unit. © 2015 Akadémiai Kiadó, Budapest, Hungary.

Nalyanya K.M.,Egerton University | Rop R.K.,Egerton University | Onyuka A.,Kenya Industrial Research and Development Institute KIRDI | Migunde P.O.,Egerton University | Ngumbu R.G.,Egerton University
Journal of Applied Polymer Science | Year: 2016

Cowhide, a natural biopolymer of collagen, forms raw material for leather, biomaterials, and food, among others. Thermal and mechanical analysis was done using dynamic mechanical analyzer. Effect of tanning and natural solar radiations on the storage modulus, tan δ, and thermal stability of pickled and tanned cowhides has been investigated in the temperature range of 30-240C. Tanning has been shown to enhance thermal stability and storage modulus. However, tanning decreases its dissipative capability. Thermal stability of both tanned and pickled hide decreased with time of exposure to irradiation. Storage modulus dropped drastically within the initial 6 h of natural solar radiations before rising progressively with the subsequent 12, 18, and 24 h, although still lower than that for nonirradiated sample. Thermal-mechanical analysis proved to be a useful technique for assessing effect of tanning and natural solar radiations on cowhide. © 2015 Wiley Periodicals, Inc.

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