Papers by Allan J Komakech
Sustainability, 2019
Growth in cattle population is associated with increased manure generation whose current manageme... more Growth in cattle population is associated with increased manure generation whose current management in low-income countries is associated with health and environmental problems as well as low utilization rates. This trend can be reversed by promoting better manure management technologies. This study assessed vermicomposting as one of the technologies to manage organic wastes, using the case study in Uganda. A vermicomposting system using cattle manure and earthworms (Eudrilus euginea) was monitored for one year with the harvesting of products (compost, earthworm biomass) after every three months. Vermicompost samples from the beginning of the experiment and after every harvest were analyzed for the following parameters: pH, ash content, volatile and total solids, nutrients N, P, K, and C. Emissions of CO2, CH4, NH3, and N2O were also measured. Material flow analysis was used to determine the flows and retention of nutrients within the system. Results showed that total solids, ash, N...
African Journal of Environmental Science and Technology, 2016
Inadequate information on physiochemical properties of faecal sludge leads to inappropriate desig... more Inadequate information on physiochemical properties of faecal sludge leads to inappropriate design of pit emptying devices and poor faecal sludge disposal contributing to environmental pollution. This study undertook a critical analysis of physiochemical properties of feacal sludge that influence design and performance of pit emptying devices and faecal sludge disposal for improved faecal sludge management in urban slums. The physiochemical properties determined were; Moisture content (MC), ash content (AC), total solids (TS), volatile solids (VS), nitrogen (N), phosphorous (P), potassium (K) and pH. Samples were collected from 55 unlined pits at depths of 0, 0.5, 1 and 1.5 m from pit surface. The unlined pits in this study were purposively selected from slums in Kampala. A sample of 300 g was sucked from each depth using a manual sampling tool and emptied into a plastic container. The container was then wrapped in a black plastic bag and transported in cooler boxes to the lab for analysis. The properties were subjected to Principal Component Analysis to isolate the critical parameters that affect pit emptying and faecal sludge disposal. The mean results were: MC of 86 ± 8.37%; TS of 0.14 ± 0.08 g/g wet sample; VS of 0.73 ± 0.32 g/g dry sample; pH of 8.0 ± 1.5; AC of 0.35± 0.18 g/g dry sample; TN of 3.5 ± 0.08%; K of 2.2± 0.13% and P of 1.4± 0.05%. It was concluded that physiochemical properties in Ugandan pits are comparable to those of global pits except for the acidic conditions at top surface in some pits, and higher moisture content in pits due to the high water table. PCA results showed that moisture content and total solids affected pit emptying techniques while fractional content of N, P and pH affect most choice of faecal sludge disposal technique.
Smart Agricultural Technology
Introduction Worldwide, the numerous challenges associated with inadequate access to safe drinkin... more Introduction Worldwide, the numerous challenges associated with inadequate access to safe drinking water are well known: 1.8 billion people use water contaminated with faecal pathogens [1] and 3 900 children die daily from diseases transmitted through unsafe water [2]. In Uganda, although piped water coverage has increased over the years, treatment of piped supplies is not guaranteed, and only 5 % of the population have access to a tap on their premises [3]. Residents without access to piped water use untreated sources, which are prone to contamination with enteric pathogens (Photo 1). As a result, 29 300 children die annually in Uganda from diarrhoeal diseases [4]. Ultrafiltration (UF) is a promising technology for decentralised water treatment in developing countries; yet, a major hindrance to long term operation of UF is membrane fouling. This leads to permeate flux losses, increased membrane cleaning routines and high operating costs. Several researchers have studied coagulation...
Agricultural Engineering International: The CIGR Journal, 2017
Soil exhaustion and nutrient depletion are major constraints to pineapple farming in Uganda. This... more Soil exhaustion and nutrient depletion are major constraints to pineapple farming in Uganda. This study explored potential for using on-farm waste from pineapple farming to conserve soil fertility and enhance agricultural productivity. Data collection was done using key informant interviews, focus group discussions, and a semi structured survey questionnaire administered to 109 randomly selected pineapple farmers and processors. The data was analysed in SPSS to generate descriptive statistics for selected variables followed by cross tabulation to explore linkages between the variables. Results indicate that farmers engaged in pineapple farming, have diverse socioeconomic backgrounds but activities engaged in are not significantly associated with socioeconomic variables examined except farming experience and gender. The major challenges faced by the farmers included soil exhaustion, lack of appropriate technologies, inappropriate pineapple waste management and decline in yield. It wa...
Waste Management, 2021
This study explored the production and evaluation of briquettes made from dried fecal sludge mixe... more This study explored the production and evaluation of briquettes made from dried fecal sludge mixed with fresh food waste as a dual strategy to solve energy poverty and poor sanitation problems in Ugandan slums. Cylindrical briquettes measuring 82 mm height by 76 mm diameter were produced from dried fecal sludge (FS) alone, and FS mixed separately with pineapple peels (FS + PP), charcoal fines (FS + CD), and bean husks (FS + BH) in a mix ratio of 50% FS: 50% biomass (wt/wt basis) using red soil as the binder. Physiochemical characteristics and fuel thermal efficiency of the briquettes were tested following ASTM standards and were compared to wood-derived charcoal and commonly traded briquettes on market in Uganda. The average moisture content was 5.1%. Bulk density was highest in FS briquettes (1.12 g/cm3) and lowest in FS + BH (0.847 g/cm3). Volatile matter (VM) was highest in FS + PP (39%) and lowest in FS alone (25.7%). The average ash content was 30.4%. FS + PP had the highest calorific value (17.92 MJ/kg) while FS alone had the lowest (6.19 MJ/kg). The highest burning rate was recorded in FS + CD briquettes (8 g/min) and was lowest in FS + PP (4 g/min). Based on the calculated burning rates and calorific values, the economic advantage calculations implied that blending one ton of dry FS with one ton of dry pineapple peels for fuel briquettes, and their use as a substitute could save consumers about USD 620 per ton of wood charcoal foregone.
Journal of Environmental Management, 2021
The largest portion of pineapple peels and pulp generated from production points is disposed of h... more 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. Credit author contribution statement Ahamada Zziwa: Principal investigator of the project, fund administrator, experimental design, final manuscript-review & editing. Joseph Jjagwe: Experimental design, data collection and analysis, Writingoriginal draft of the manuscript. Simon Kizito: Experimental design, Formal analysis, manuscript review & editing. Isa Kabenge: Experimental set up: Formal analysis, manuscript draft writing, review & editing. Allan John Komakech: Experimental design, manuscript preparation and reviews. Henry Kayondo: Data collection, routine monitoring and participation in manuscript preparation.
Journal of Cleaner Production, 2021
As many regions in sub-Saharan Africa, the border region of Kenya (KE) and Uganda (UG) has faced ... more As many regions in sub-Saharan Africa, the border region of Kenya (KE) and Uganda (UG) has faced a declining soil fertility for decades, resulting from soil erosion, intensely managed agricultural soils due to population pressure and small inputs of mineral and organic fertilizers. With limited financial means, farmers need measures and/or technologies that effectively reduce nutrient losses or increase inputs at a low cost. In this study, four such measures are in focus, namely erosion reduction practices, vermicomposting of animal manure, collection of human urine in jerry cans and, collection of human excreta in urine-diverting dry toilets. Current soil nutrient balances in five districts in the Sio-Malaba-Malakisi River Basin and the potential of these measures to reduce the soil nutrient deficit are studied using the method of material flow analysis and the software STAN. Furthermore, crop-nutrient-response functions are used to determine their potential impact on maize harvests. Overall, results reveal that there exists a non-negligible and exploitable potential of local resources to reduce the soil nutrient deficit, improve harvests and in turn food security of the smallholder farmers in the region. Soil nutrient deficits could be reduced by 20-30%, 23-42% and 9-15% for nitrogen (N), phosphorus (P) and potassium (K), respectively. Subsequently, maize harvests could be increased by 8-40%, depending on the applied technology and area. This research provides useful insights for agricultural extension workers, politicians and researchers alike, highlighting that simple and easily available technologies can harness similar amounts of nutrients as more complex and expensive ones if all specific technology-constraints are adequately incorporated in the analyses.
Livestock Science, 2021
Abstract The demand and cost of animal-based protein sources for broiler chickens production like... more Abstract The demand and cost of animal-based protein sources for broiler chickens production like fish meal has increased in many countries. An alternative protein source can be earthworm meal (EWM). A study was conducted to evaluate the effects of supplementing broiler chickens diets with EWM derived from dried Eudrilus eugeniae on growth performance, carcass attributes, and the meat quality of broiler chickens. The starter and finisher basal diets were formulated to contain 10% fish meal and it was replaced with 0, 1, 3, 5, and 7% EWM. For the experiment, 150 one-day-old broiler chickens were randomly assigned to the 5 diets with 3 pens per diet and 10 broiler chickens per pen. Based on the data recorded in the experiment, the body weight gain (BWG), and the feed intake (FI) were computed. At 6 wk of age, 3 broiler chickens were randomly selected from each pen to assess their organ weights and sensory characteristics. Overall, there was a quadratic and cubic effect on BWG when EWM supplementation was increased (P
Science of The Total Environment, 2020
Journal of Sustainable Bioenergy Systems, 2020
The current shortage of energy resources coupled with environmental degradation problems resultin... more The current shortage of energy resources coupled with environmental degradation problems resulting from deforestation in Uganda has contributed to increased demand for renewable energy resources including municipal organic solid waste and agricultural residues. However, organic waste from Municipal Solid Waste (MSW) may contain contaminants that are harmful to public health and the environment. This study determined the heavy metal concentration in MSW in Kampala City, Uganda. Also, the physicochemical properties of briquettes produced from the MSW were compared with charcoal. The waste samples were collected from residential, institutional and market areas over a period of two weeks. They were then analyzed for the presence of heavy metals. Briquettes were made from the bio-waste and were subjected to calorific and proximate analysis. Results indicated that the mean concentrations of Cd, Cr, Cu, Fe, and Pb were 1.25 mg/kg, 2.04 mg/kg, 38.2 mg/kg, 3.97 mg/kg and 1.99 mg/kg respectively while Hg was not detected. The calorific values of briquettes ranged from 8.9 to 15.3 MJ/kg and were lower than those of charcoal. Heavy metal concentrations in bio-waste collected were below the permissible acceptable limits. These findings indicate that the sampled MSW does not pose a health hazard arising from the presence of such heavy metals and therefore could be a safe source of renewable energy.
Science of The Total Environment, 2020
This study investigated the occurrence and removal in wastewater and water bodies in Nakivubo wet... more This study investigated the occurrence and removal in wastewater and water bodies in Nakivubo wetland area and Inner Murchison Bay, Lake Victoria, of common prescription and non-prescription pharmaceutically-active substances (PhACs) sold in Kampala city, Uganda. A questionnaire was sent to 20 pharmacies in Kampala, to identify the most commonly sold PhACs in the city. During two sampling campaigns, samples were collected from Bugolobi wastewater treatment plant (WWTP) influent and effluent and surface water samples from Nakivubo channel, Nakivubo wetland and Inner Murchison Bay. The concentrations of 28 PhACs, organic matter, solids and nutrients in water samples were analysed. Ciprofloxacin (antibiotic), cetirizine (anti-allergy), metformin (anti-diabetes), metronidazole (antibiotic) and omeprazole (gastric therapy) were reported by pharmacies to be the PhACs most commonly sold in the study area. Chemical analysis of water samples revealed that trimethoprim (antibiotic) and sulfamethoxazole (antibiotic) were the dominant PhACs in water from all sites except Lake Victoria. Other PhACs such as atenolol (anti-hypertensive), carbamazepine (anti-epileptic) and diclofenac (anti-inflammatory) were also found at all study sites except Lake Victoria. ∑PhACs in effluent from Bugolobi WWTP (13000-37,600 ng L-1) was higher than in the corresponding influent (4000-28,000 ng L-1), indicating poor removal of PhACs within the WWTP. ∑PhACs decreased by a factor of 2-6 between Bugolobi WWTP effluent and Nakivubo channel (5700 ng L-1), due to dilution and sorption to channel sediment, and by a factor of 1-3 between the Nakivubo channel and Nakivubo wetland (3900-5400 ng L-1), due to sorption to sediment and uptake by plants in the wetland. No detectable levels of PhACs were found in water from Lake Victoria. Overall, this investigation demonstrated that PhACs in wastewater enter Nakivubo water system. Thus, Bugolobi WWTP needs to be upgraded to improve PhACs removal from wastewater. Considering the high occurrence of antibiotics in the water system in Kampala, development and spread of antimicrobial resistance within the area should also be investigated.
Water SA, 2017
Occurrence and survival of pathogens in faecal sludge was investigated in unlined pit latrines at... more Occurrence and survival of pathogens in faecal sludge was investigated in unlined pit latrines at varying depths in peri-urban areas of Kampala city, Uganda. A total of 55 unlined pit latrines, 7 private and 8 rental unlined pit latrines were sampled in the first and second phases (representing the rainy season) and 40 pits in the third phase (representing dry season), and analysed for indicator organisms and pathogens from 4 pit latrine sludge layers, at depths of 0, 0.5, 1.0 and 1.5 m, following APHA standard methods. Physico-chemical parameters of the faecal sludge were also measured. Three sampling phases were undertaken to determine the effect of seasonal variation. Results indicate that the mean temperature and pH were 25.4 ± 1.14°C and 8.0 ± 1.5, respectively; and moisture content increased with pit sludge depth, except between Depths 3 and 4. Average moisture content was 86.3 ± 3%. The measured parameters varied significantly (P > 0.05) between seasons. The mean reduction in total coliforms, thermo-tolerant coliforms, E. coli, and faecal enterococci with sludge depth was significant at all depths (P < 0.05), but the least significant difference was not significant at depth levels of 1.0 m and 1.5 m. Salmonella was only detected at the top layer of faecal sludge in 60% of Phase 2 samples and in only 20% of the samples in Phase 3. About 200-4 100 eggs/g of strongyles were found in 98% of the samples and 100-1 600 eggs/g of ascarids in 55% of the samples. Temperature, pH and moisture content did not show a significant correlation with observed reductions of indicators and pathogens. With extrapolation of the generated regression models, a pit of 8 m can be recommended for reduction of bacteria. It is recommended that protective field gear be used during pit emptying and that faecal sludge treatment should be done to reduce pathogens before disposal into the environment.
Water Supply, 2019
Decentralized membrane-based water treatment represents an attractive and viable approach to safe... more Decentralized membrane-based water treatment represents an attractive and viable approach to safe water supply in low-income areas, but its widespread adoption requires cost-effective antifouling strategies. Although the antifouling mechanisms of Al-based coagulants have been widely investigated, there is little data about their impact on costs and treatment efficiency for decentralized membrane-based systems. In this study, a comparative assessment of two decentralized ultrafiltration (UF) units with and without polyaluminum chloride (PACl) coagulation was undertaken to evaluate the influence of coagulation on the fouling, water quality, and costs nexus. The results showed that PACl suppressed both total fouling and hydraulically irreversible fouling. A matched-pair analysis also revealed that PACl improved the permeate quality by enhancing the removal of particulates and dissolved organics. Compared with the conventional UF system, the hybrid coagulation–UF system contributed to a...
Science of The Total Environment, 2018
Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in ... more Occurrence and concentrations of 26 per-and polyfluoroalkyl substances (PFASs) were evaluated in wastewater, surface water, soil and crop plants (yam (Dioscorea spp.), maize (Zea mays) and sugarcane (Saccharum officinarum)) in Nakivubo wetland and Lake Victoria at Kampala, Uganda. ∑PFAS concentrations in effluent from Bugolobi wastewater treatment plant (WWTP) were higher (5.6-9.1 ng L −1) than in the corresponding influent (3.4-5.1 ng L −1), indicating poor removal of PFASs within the WWTP. ∑PFAS concentrations decreased by a factor of approximately five between Nakivubo channel (8.5-12 ng L −1) and Lake Victoria (1.0-2.5 ng L −1), due to dilution, sorption to sediment and uptake by plants in the wetland. ∑PFAS concentrations were within the range 1700-7900 pg g −1 dry weight (dw) in soil and 160 pg g −1 dw (maize cobs) to 380 pg g −1 dw (sugarcane stems) in plants. The dominant PFASs were perfluorohexanesulfonate (PFHxS) in wastewater, perfluorooctanoate (PFOA) in surface water, perfluorooctanesulfonate (PFOS) in soil and perfluoroheptanoate (PFHpA) and PFOA in different plant tissues, reflecting PFAS-specific partitioning behaviour in different matrices. Soil-water partitioning coefficient (log K d) in wetland soil under yam was lowest for short-chain PFHxA (1.9-2.3 L kg −1) and increased with increasing chain length to 2.8-3.1 L kg −1 for perfluoroundecanoate (PFUnDA) and 2.8-3.1 L kg −1 for perfluoroctanesulfonate (PFOS). The log K oc values ranged between 2.2 and 3.6 L kg −1 , with the highest log K oc estimated for long-chain perfluorocarbon PFASs (i.e. PFUnDA 3.2-3.5 L kg −1 and PFOS 3.2-3.6 L kg −1). The concentration ratio (CR) between plants and soil was b1 for all PFASs and plant species, with the highest CR estimated for PFHpA (0.65-0.67) in sugarcane stem and PFBS (0.53-0.59) in yam root.
Water Supply, 2017
In order to optimize the operating conditions for a combined polyaluminum chloride (PACl) coagula... more In order to optimize the operating conditions for a combined polyaluminum chloride (PACl) coagulation/flocculation and ultrafiltration process for treating potable water, the main, second order and interaction effects of PACl dose and flocculation retention time (FRT) on permeate turbidity, UV254 and membrane permeability were investigated using a 100 kDa hollow fiber membrane operated in the dead-end mode. A multilevel factorial design was used to determine the relevant ranges of the two factors for optimization. A 22 central composite design (CCD) was then used to develop mathematical correlation models for the optimum operating conditions. The main effect of PACl dose was the most significant factor on all the responses. For permeability, both the main effect of FRT and FRT–PACl dose interactions were found to be insignificant. The optimum PACl dose and FRT for the feed water were 20 mg/L and 14 min, respectively. Corresponding permeate turbidity, UV254 and permeability were 0.15...
Journal of Irrigation and Drainage Engineering, 2017
Policy makers in sub-Saharan African (SSA) countries have identified irrigation as a key ingredie... more Policy makers in sub-Saharan African (SSA) countries have identified irrigation as a key ingredient to boosting food security and income as well as a precursor for agricultural development. However, most SSA countries have hardly exploited their irrigation potential. The overarching aim of this paper is to critically examine factors constraining exploitation of irrigation potential in Uganda. Lessons learned from previous interventions and successes elsewhere from countries comparable to Uganda are drawn and future perspectives to guide effective irrigation planning and development are recommended. From this paper, it is evident that there is no single blanket solution to constraints of irrigation development in SSA. All strategies should be implemented in a holistic manner dictated by specific local conditions. The key to successful adoption of irrigation lies in building the national irrigation capacity, improving access to reliable water for irrigation in proximity of the farms, streamlining extension services for farmers, addressing economic aspects of irrigation, and streamlining land tenure systems and management. It is recommended to operationalize government policy on irrigation by developing national guidelines on irrigated agriculture.
Infection Ecology & Epidemiology, 2016
Background: Vermicomposting is a mesophilic process using earthworms to efficiently and at low co... more Background: Vermicomposting is a mesophilic process using earthworms to efficiently and at low cost process large volumes of organic waste. It has been suggested to not only increase soil fertility but also increase biomass of beneficial bacteria while reducing harmful bacteria. The aim of this study was to set up a strategy to investigate and characterise the viral as well as the bacterial composition of a vermicomposting system. Material and methods: The vermicomposting unit used in this study was placed at the Makerere University Agricultural Research Institute Kabanyolo on the outskirts of Kampala, Uganda, and was fed with 80% cattle manure and 20% food waste. On Day 172, the compost was terminated and compost samples were collected from three layers of the unit: the top, the middle and the bottom layer. A metagenomic approach was then applied to characterise the viral and bacterial composition of the vermicomposting system. Results and discussion: A high abundance and diversity of bacteria were identified. Proteobacteria was the largest phyla in the compost (mainly Alpha-, Gamma-and Betaproteobacteria), constituting almost 65% of the bacterial reads in the data sets. DNA samples from several possible pathogenic bacteria, such as Salmonella spp., Escherichia coli, Enterobacter spp., Enterococcus spp. and Clostridium spp, were detected in the vermicompost, suggesting that there might still be harmful bacteria in the vermicast. Phages constituted the main viral group; apart from phages, mainly insect viruses were identified. The only animal or human virus identified was kobuvirus. In summary, metagenomic analysis was shown to be an efficient technology to characterise the microbial composition of vermicast. The data from this study contribute to a better understanding of the microbes present in this kind of composting system and can help determine measures necessary for safe manure handling.
Journal of Environmental Management, 2016
Urban animal farming is becoming increasingly important in feeding the growing population of many... more Urban animal farming is becoming increasingly important in feeding the growing population of many sub-Saharan African cities. However, management of the animal manure generated is proving to be challenging due to space restrictions. Vermicomposting is one of the methods proposed to address this challenge. This study investigated the environmental performance of the vermicompost system by measuring the gaseous emissions generated from the system. In addition, the vermicompost system was compared with other manure management systems currently in use, using life cycle assessment (LCA) methodology. The emissions factors for the vermicompost system were found to be 10.8, 62.3 and 12.8 g/ Megagram biowaste for methane, nitrous oxide and ammonia, respectively. LCA showed satisfactory performance of vermicomposting in terms of global warming and eutrophication potential, although if the vermicompost generated is dumped, this could lead to increased eutrophication. However, this is still much lower than the eutrophication caused by open dumping of untreated manure.
Environmental Engineering Research, 2016
Conventional treatment techniques cannot meet the stringent modern water quality regulations eman... more Conventional treatment techniques cannot meet the stringent modern water quality regulations emanating from the need to provide high quality drinking water. Therefore, a number of studies have suggested low pressure membrane filtration as a worthwhile alternative. However, a major constraint to the extensive use of this technology in low and middle income countries is the high operating and maintenance costs caused by the inherent predisposition to membrane fouling. Notwithstanding, pretreatment of feed water using techniques such as coagulation, adsorption, oxidation and bio-filtration is believed to control fouling. In this review paper, the existing scientific knowledge on membrane fouling and pretreatment techniques for controlling fouling in low pressure membranes is analyzed with the aim of providing new and valuable insights into such techniques, as well as unveiling crucial issues noteworthy for further studies. Among the techniques reviewed, coagulation was observed to be the most cost-effective and will remain the most dominant in the coming years. Although oxidants and magnetic ion exchange resins can also control fouling, the propensity of oxidants to form health treating precursors and the high economic implications of magnetic ion exchange resins will hinder their adoption in developing countries.
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Papers by Allan J Komakech