NRU :: Browsing by Author "Kizito, Simon"

Browsing by Author "Kizito, Simon"

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Effect of thermal shock on the grates of improved charcoal cook-stoves made from different materials
(Energy for Sustainable Development, 2021) Tumutegyereize, Peter; Muwanguzi, Simon; Ayaa, Fildah; Kizito, Simon; Wanyama, Joshua
From the current literature on cook stoves, it remains unclear on which is the best temper and the alternative soils that can be used in the production of charcoal cook-stoves that are resistant to thermal shock. To this end, a study was conducted to determine which soil type and mixing ratio that can produce the highest thermal shock resistance when used as grates. The grates made of clay, red and anthill soils each mixed with shale rock in ratios of 1:0; 1:1; and 3:1 were compared. The grates were fired and then heated in a furnace set at 400 °C for 1 h and subjected to two cooling treatments; rapid cooling by quenching inwater and cooling at ambient temperatures, for seven subsequent cycles after being heated. The shock resistance for all the grates made from different soil types and different mix ratios was measured based on crack initiation and propagation according to ASTM C1525-04 standards. The results showed that clay soil mixed with shale rock in the ratio of 3:1 had the highest thermal shock resistance with no crack initiation throughout the heating and cooling cycles, followed by anthill soil mixed with shale rock in the ratio of 1:1. Therefore, charcoal stove users and manufacturers can expect a better quality productwith high durability if shale rock is used to temper the cook-stoves in comparison to burnt bricks that are currently commonly used in Uganda. The method used in this work can be applied in other regions to come up with more material ratios that are resistant to thermal shock.
Evaluation of slow pyrolyzedwood and rice husks biochar for adsorption of ammonium nitrogen from piggery manure anaerobic digestate slurry
(Science of the Total Environment,, 2015) Kizito, Simon; Wu, Shubiao; Kirui, W. Kipkemoi; Lei, Ming; Lua, Qimin; Baha, Hamidou; Donga, Renjie
Due to its high adsorption capacity, the use of biochar to capture excess nutrients fromwastewater has become a central focus in environmental remediation studies. In this study, its potential use in adsorption and removal of ammonium in piggery manure anaerobic digestate slurry was investigated. The adsorbed amount of NH4 +-N (mg·g−1) and removal percentage as a function of adsorbent mass in solution, adsorbent particle size, NH4 +-N concentration in the effluent, contact time, pHand temperaturewere quantified in batch equilibriumand kinetics experiments. The maximum NH4 +-N adsorption from slurry at 1400 mg N·L−1 was 44.64 ± 0.602 mg·g−1 and 39.8 ± 0.54 mg·g−1 for wood and rice husk biochar, respectively. For both biochars, adsorption increased with increase in contact time, temperature, pH and NH4 +-N concentration but it decreased with increase in biochar particle size. Furthermore, the sorption process was endothermic and followed Langmuir (R2 = 0.995 and 0.998) and Pseudo-second order kinetic models (R2 = 0.998 and 0.999). Based on the removal amounts, we concluded that rice husk and wood biochar have potential to adsorb NH4 +-N from piggery manure anaerobic digestate slurry, and thus can be used as nutrient filters prior to discharge into water streams.
Nutrient recovery from pineapple waste through controlled batch and continuous vermicomposting systems
(Journal of Environmental Management, 2021) Zziwa, Ahamada; Jjagwe, Joseph; Kizito, Simon; Kabenge, Isa; Komakech, Allan John; Kayondo, Henry
The largest portion of pineapple peels and pulp generated from production points is disposed of haphazardly contributing to a number of environmental and health challenges. However, these wastes contain valuable plant nutrients that could be recovered to boost soil fertility, and increase agricultural production. This study evaluated the variation in physico-chemical parameters in batch and continuous vermicomposting systems as potential pathways for nutrient recovery from pineapple waste. The study compared the efficiency of waste reduction and nutrient recovery for batch (B), and continuous (C) vermicomposting systems during a 60-day period. The substrates were pineapple peels (PW), and cattle manure (CM) fed in a ratio of 4:1 (w/w). Control reactors were fed with 100% CM in both the feeding modes. Results indicated that waste degradation was 60%, and 54% while earthworm biomass increased by 57% and 129% for BPW, and CPW, respectively. pH significantly decreased with time in both systems. Total phosphorous increased with vermicomposting time with that of B being significantly higher than C systems. Nitrogen, potassium, and sodium significantly increased in the control experiments while the three elements significantly reduced for BPW, and CPW owing to high leachate production in the latter. The N, P, K, and C retention in vermicompost was 24.2%, 90.4%, 67.5%, 41.1%, and 32.6%, 91.2%, 79.3%, 46.1%, for BPW and CPW, respectively. Continuous systems produced higher earthworm biomass and retained more nutrients in vermicompost than batch systems, and can therefore, be recommended as better systems for pineapple waste vermicomposting.
Phosphate removal from aqueous solution using iron oxides: adsorption, desorption and regeneration characteristics
(Journal of Colloid and Interface Science, 2018) Ajmal, Zeeshan; Muhmood, Atif; Usman, Muhammad; Kizito, Simon; Lu, Jiaxin; Dong, Renjie; Wu, Shubiao
Dynamics of phosphate (PO4 3-) adsorption, desorption and regeneration characteristics of three lab-synthesized iron oxides, ferrihydrite (F), goethite (G), and magnetite (M) were evaluated in this study. Batch experiments were conducted to evaluate the impact of several adsorption parameters including adsorbent dosage, reaction time, temperature, pH, and ionic strength. The results showed that PO4 3- adsorption increased with reaction time and temperature while it decreased with an increase in solution pH. Adsorption isotherm data exhibited good agreement with the Freundlich and Langmuir model with maximum monolayer adsorption capacities of 66.6 mg·g-1 (F), 57.8 mg·g-1 (M), and 50.5 mg·g-1 (G). h u u Δ < ΔH > ΔS > demonstrating that PO4 3- adsorption onto tested minerals is endothermic, spontaneous, and disordered. The PO4 3- removal mostly occurred via electrostatic attraction between the sorbate and sorbent surfaces. Moreover, the PO4 3- sorption was reversible and could be desorbed at varying rates in both neutral and alkaline environments. The good desorption capacity has practical benefits for potential regeneration and re-use of the saturated particles in wastewater treatment systems.
Potential of densification of mango waste and effect of binders on produced briquettes
(Agricultural Engineering International: CIGR Journal, 2014) Katimbo, Abia; Kiggundu, Nicholas; Kizito, Simon; Kivumbi, Hussein B.; Tumutegyereize, Peter
In Uganda, agro-processing of fruits produces large volumes of agricultural wastes, much of which are not utilized but disposed in the landfill. This study explored the possibility of producing biomass briquettes from mango waste (seed covers) that could be used for energy supply in small factories and for domestic cooking. Mangoes were selected because of their abundance throughout the country and its high fiber content which is a good property for a raw material for briquetting. Dried mango seed covers were crushed to particles of size 2 mm and bonded with three different binders; starch, starch-clay soil, and starch-red soil. The best mixing ratios for briquettes were; 4:1 (seed-cover: starch), 9:2:1 (seed cover: starch: clay soil), and 16:4:1 (seed-cover: starch: red soil). The formed briquettes were subjected to several standard methods to verify their suitability as fuels. The briquette properties tested were moisture content, volatile matter, ash content, fixed carbon content, calorific value, compressive strength, and gas emissions. Results showed that briquettes bonded with only starch had higher fuel properties (p≤0.05) with low: moisture content (11.9%), volatile matter (16.0%), ash content (2.8%) and emissions (0.178% CO, 0.0021% (CH)X , 1.14% CO2 and no NOx); higher fixed carbon (69.3%), breaking strength (maximum force, 34 N and compressive stress, 273 N/mm2) and calorific values (16,140 kJ/kg) compared to starch-red soil and starch-clay soil briquettes. But after a linear regression analysis, results further showed that maximum force (R2 = 0.636) and ash content (R2 = 0.520) were good indicators of energy content of a particular briquette. However, more research is needed on using other binder types rather than cassava starch which is considered as food.
Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand
(Sustainability, 2019) Kizito, Simon; Luo, Hongzhen; Lu, Jiaxin; Bah, Hamidou; Dong, Renjie; Wu, Shubiao
Recycling and value-added utilization of agricultural residues through combining technologies such as anaerobic digestion and pyrolysis could double the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. This study assessed the beneficial application of biochar to soil to recycle digestate nutrients, improve soil quality, and reduce conventional chemical fertilizer. The addition of digestate-enriched biochar improved soil quality as it provided higher soil organic matter (232%–514%) and macronutrients (110%–230%) as opposed to the unenriched biochar and control treatments. Maize grown in soil amended with digestate-enriched biochar showed a significantly higher biomass yield compared to the control and non-enriched biochar treatments but was slightly lower than yields from chemical fertilizer treatments. The slightly lower yield (20%–25%) achieved from digestate-enriched biochar was attributed to slower mineralization and release of the adsorbed nutrients in the short term. However, digestate-enriched biochar could in the long term become more beneficial in sustaining soil fertility through maintaining high soil organic matter and the gradual release of micronutrients compared to conventional chemical fertilizer. Positive e ects on soil micronutrients, macronutrients, organic matter, and biomass yield indicates that enriched biochar could partly replace chemical fertilizers and promote organic farming in a circular economy concept.
Structural suitability of 10-year old Pinus caribaea timber with a forest fire history in farm buildings
(Agricultural Engineering International: CIGR Journal, 2020) Zziwa, Ahamada; Mukasa, Joseph; Kizito, Simon
Forest fires in pine and eucalyptus plantations are common in Uganda especially in the dry periods. In an event of fire gutting a nearly mature plantation, tree farmers usually try to reduce losses by extracting and lumbering the residual trees for use in agricultural buildings. However, there is no empirical data to guide material selection based on strength and structural integrity of the timbers from burnt plantations. Therefore, this study investigated the effect of fires on selected physical and strength properties of timber extracted from a 10-year old stand of Pinus caribaea that had been burnt. Test specimens were prepared and tested for Modulus of elasticity (MOE), Modulus of Rupture (MOR) and compression parallel to the grain using a Testometric AX M500 – 25KN Universal Testing Machine in accordance with ASTM D 198 and BS 373. For comparison purposes, structural size specimens from the same age stands that were unaffected by fire were concurrently tested. The data were statistically analyzed using one-way Analysis of Variance test. The results indicated that burnt trees had significantly lower density, MOE and MOR than that of the unburnt trees. It is recommended that timber extracted from burnt trees should not be used for high strength structural purposes but could rather be used in low strength construction works such as shuttering and ceiling works.
Treatment of anaerobic digested effluent in biochar-packed vertical flow constructed wetland columns: Role of media and tidal operation
(Science of the Total Environment, 2017) Kizito, Simon; Lv, Tao; Wua, Shubiao; Ajmal, Zeeshan; Luo, Hongzhen; Dong, Renjie
Three types of vertical flow constructed wetland columns (VFCWs), packed with corn cob biochar (CB-CW), wood biochar (WB-CW) and gravel (G-CW) under tidal flowoperations, were comparatively evaluated to investigate anaerobic digested effluent treatment performance and mechanisms. Itwas demonstrated that CB-CWand WB-CWprovide significantly higher removal efficiencies for organic matter (N59%), NH4 +-N (N76%), TN (N37%) and phosphorus (N71%), compared with G-CW (22%–49%). The higher pollutants removal ability of biocharpacked VFCWs was mainly attribute to the higher adsorption ability and microbial cultivation in the porous biochar media. Moreover, increasing the flooded/drained ratio from 4/8 h to 8/4 h of the tidal operation further improved around 10% of the removal of both organics and NH4 +-N for biochar-packed VFCWs. The phosphorus removal was dependent on the media adsorption capacities through the whole experiment. However, the NH4 +-N biodegradation by microbial communities was demonstrated to become the dominant removal mechanismin the long termtreatment,which compensated the decreased adsorption capacities of the media. The study supported that the use of biochar would increase the treatment performance and elongate the lifespan of CWs under tidal operation.
Views on Depression From Traditional Healing and Psychiatry Clinics in Uganda: Perspectives From Patients and Their Providers
(Journal of Cross-Cultural Psychology, 2017) Johnson, Laura R.; Chin, Eu Gene; Kajumba, Mayanja; Kizito, Simon; Bangirana, Paul
In Uganda, depression is a growing concern, yet mental health professionals are in short supply, and help is often sought from traditional healers. To develop an integrated system of care, we must understand sociocultural aspects of depression including beliefs about help seeking and treatment. In a mixed methods study, we used semi-structured interviews and self-report measures to assess depressed patients (N = 30) seeking treatment in traditional healing (n = 15) and psychiatry clinics (n = 15) near Kampala, Uganda. We assessed demographics, symptoms, treatment characteristics, and explanatory models (EMs) of depression (e.g., labeling the problem, cause, impact on life, best type of treatment). We predicted differences across treatment settings. To further explore EMs, we assessed differences in EMs of patients and their providers by interviewing patient–provider dyads (n = 8 dyads). Patients in both settings were similar in demographics, symptoms, perceived cause, seriousness, and impact of depression. However, patients at traditional clinics were more likely to desire herbal remedies, while those in psychiatry clinics were more likely to desire modern medication. Patient–provider dyads also had different treatment beliefs, with patients desiring financial assistance, social support, and medication, and providers more likely to suggest counseling or advice. The study highlights the need to understand diverse beliefs and treatment trajectories in a multicultural context.

Browsing by Author "Kizito, Simon"

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