Browsing by Author "Okure, Mackay A. E."

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    Decentralized opt 1 ions for faecal sludge management in urban slum 2 areas of Sub-Saharan Africa: A review of technologies, practices and 3 end-uses
    (Resources, Conservation and Recycling, 2015) Semiyaga, Swaib; Okure, Mackay A. E.; Niwagaba, Charles B.; Katukiza, Alex Y.; Kansiime, Frank
    Faecal sludge (FS), a product from on-site sanitation systems, poses a management challenge in densely populated urban slums of Sub-Saharan Africa (SSA). Currently, FS or its liquid fraction after dewatering is co-treated with sewage in conventional treatment plants. When dewatered, the solid stream is dried and stored further as the terminal treatment or is co-treated directly with organic solid wastes in composting or anaerobic digestion systems. To implement these, FS has to be collected and transported. Also, land is needed, but it is in most cases limited in slums or their vicinity. The collection and transport of FS from slums is costly due to lack of access, traffic congestion and long travel distances to treatment plants. Moreover, uncollected FS poses health risks and pollutes surface and/or ground water within slums. This review demonstrates that currently utilized technologies and practices fall short in various ways and discusses the possibility of minimizing FS management related costs, risks and pollution in urban slums by decentralized treatment and end-use. It also discusses the possible FS-derived end-products and their benefits to urban slum dwellers. Substitution of a part of natural materials (sand and clay) when building and/or biomass (firewood and charcoal) for cooking with FS derived end-products could multiply the benefits of improved sanitation to slum dwellers.
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    Enhancing Faecal Sludge Dewaterability and End use By Conditioning With Sawdust and Charcoal Dust
    (Environmental Technology, 2018) Semiyaga, Swaib; Okure, Mackay A. E.; Niwagaba, Charles B.; Nyenje, Philip M.; Kansiime, Frank
    Faecal sludge (FS) treatment in urban slums of low-income countries of sub-Saharan Africa is poor or non-existent. FS contains over 90% water and therefore dewatering it within slums decreases transport costs, facilitates local treatment and end-use. This study was designed to enhance the dewatering efficiency of FS, using two locally available physical conditioners (sawdust and charcoal dust), each applied at dosages of 0%, 25%, 50%, 75%, 100% and 125% TS. The optimum dosage for both conditioners occurred at 50% and 75% for cake moisture content and capillary suction time, respectively. The dewatering rate improved by 14.3% and 15.8%, whereas dewatering extent (% cake solids) improved by 22.9% and 35.7%, for sawdust and charcoal dust, respectively. The dewatering in FS conditioned with sawdust and charcoal dust was mainly governed by absorption and permeation (porosity), respectively. The FS calorific value improved (from 11.4 MJ kg−1) by 42% and 49% with 50% TS dosage of sawdust and charcoal dust, respectively. The FS structure also became porous after dewatering which hastens the subsequent drying and/or composting processes. Due to comparable performance in dewatering, sawdust or charcoal dust, whichever is locally available, is recommended to treat FS in low-income urban slum settlements.
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    "Experience from Rural Electrification in Uganda: A Case Study of a Husk Powered System in Tiribogo Village''
    (In 9th Sida Reg. Conf, 2014) Okure, Mackay A. E.; Musinguzi, Wilson; Wabwire, Andrew; Bagenda, Ssengonzi
    To address the need for electricity in some rural communities in Uganda with seasonal agricultural waste or biomass, we need a biomass to electricity conversion system. A low-cost biomass to electric energy conversion husk powered system was imported from the Husk Power Systems of India. The system was installed in 2012 in Tiribogo Village, Muduma Parish in Mpigi District supplying 32kWe power to an isolated power grid. The system has operated since October 2012 with a daily usage of 7 hours. The biomass flow rate of 30 kg/hr for maize cobs and 25 kg/hr for coffee husks. The power output measured was 34 kW with line voltage of 244 V/ 50 Hz and phase voltage 422 V with a power factor of 0.85 at the generation side. The specific fuel consumption was 0.88 kg/kWh for maize cobs and 0.74 kg/kWh for coffee husks. The system electrical efficiency was 20.5% for maize cobs and 30.2% for coffee husk. The solid waste products generated were 12% for maize cobs and 10% for coffee husks of the total biomass fuel put into the gasifier. A software business model was generated using RETScreen software, considering the total cost of inputs and cost sales, the unit cost of power was found to be US$ 0.259 (UGX 686/=). The business simple payback was 3.3 years for maize cobs and 3.4 years for coffee husks. The break even period for the business was found to be 6.2 years for maize cobs and 6.3 years for coffee husks respectively if all power generated is sold. The fact that maize cobs were offered free from the community with transport cost of USD 15 per ton and coffee husk were bought at a rate of USD 40 inclusive transport per ton caused the difference in the financial parameters. In conclusion the operation of a 32 kWe power plant was found satisfactory using the local biomass and it produced more power than the community could consume or buy at that time therefore it is recommended for the rural communities generating 7 tons of annually.
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    Simulation For Control Strategies Of Hybrid Wind/ Hydrogen Systems For Smart Grid Applications In Kampala And Tororo-Uganda
    (IJTD, 2016) Okure, Mackay A. E.; Ssali, Godfrey Ssajja; Jarall, Sad
    The production of electrolytic hydrogen using electricity generated from a non-polluting source is one of the strategies to promote access to sustainable energy in Africa. One of such system is the wind energy conversion system (WECs). This paper presents results of a system consisting of a wind turbine of 200 kW, an Electrolyzer, and a 3.5kW peak electric load connected to an electric grid required to produce 4-5kg of hydrogen per day. The electric grid is taken as large enough to serve as a back-up supply. Mathematical equations are derived for the interconnecting components of the system and programmed in MATLAB to simulate the operation and control strategies of the system. The model has been tested using wind speeds for Kampala City and Tororo Town in Uganda. This results show that it’s feasible to produce 4-5 kg of hydrogen from a non-polluting source. The smart grid monitors the hydrogen flow within storage and optimizes the flow of power from the wind generator and the electric grid to meet the hydrogen and load demand for the day. The paper demonstrates that such an integrated system has the potential to support remote investments in the production of electrolytic hydrogen from a non-polluting source for stationary and transportation activities.