SCALING UP THE OXYGENIC PHOTOGRANULE (OPG) WASTEWATER TREATMENT PROCESS

Photogranular biomass has yet to be utilized at large scale for wastewater treatment despite their potential to lower energy demand due to self-aerating capacity in addition to better process control compared to conventional technologies. An evaluation of critical driving factors affecting scaling up has yet to be undertaken. The current generation of oxygenic photogranules under hydrostatic conditions (a deviation from orthodox conditions creating other granules) limit seeding of larger reactors in time and scale. In addition, evaluating the photosynthetic productivity of granules which exist as closely commingled consortia with tightly coupled production and consumption processes, has yet to be undertaken. We experimentally evaluate the alternative generation of oxygenic photogranules under hydrodynamic conditions. The photochemical capacity of oxygenic photogranules under variable light conditions was also determined. Concomitantly, we evaluate the effects of light intensity on the performance of reactors of varying scales and the light demand therewith. Finally, granular physical attributes that impact hydrodynamic behaviour and interaction with the bulk fluid due to agitation were assessed. Oxygenic photogranules were formed only under some combinations of different pressures in 8 days, suggesting a ‘goldilocks zone’ of selection pressure interaction fostering granulation. Rapid generation of multiple granules would ease seeding of reactors higher volume reactors. OPGs phototrophic capacity was also found to increase with light intensity to a curvilinear maximum beyond which photoinhibition ensues. This implies the existence of light-limited operating conditions below maximal sunlight intensities. Photoelasticity was also observed for granules treated under different light stress with apparent adaptability to abiotic stresses. Moreover, the light dependency is influenced by reactor design and operation, allowing for recovery of the photosynthetic mechanism and selecting for different microbial dominance. This, in turn, affects different treatment metrics in rectors at a different scale. No linear relationship was observed between reactor performance and increasing light intensity while density, porosity and permeability were found to be in the range of other granular biomass. No spontaneous granulation has been recorded in conventional wastewater basins. We surmise that this could be due to a mismatch of conditions suppressing potential granulation. Altering the magnitudes of these o could potentially result in the formation of granular aggregates

Differences in the epidemiology of theileriosis on smallholder dairy farms in contrasting agro-ecological and grazing strata of highland Kenya

A prospective cohort study was conducted in five purposively-sampled agro-ecological zone (AEZ)-grazing system strata in Murang’a District, Kenya, between March 1995 and June 1996. The study strata were selected based on a preliminary characterization study to represent the widest range of risks to East Coast fever (ECF) in the District and included zero-grazing and open-grazing farms. In total, 225 calves from 188 smallholder farms were examined from birth to 6 months of age and visited within the first 2 weeks of life and thereafter at bi-weekly intervals for up to 14 visits. The purpose of the study was to characterize the differences in epidemiology (risks of infection, morbidity and mortality) and potential control of ECF between the selected strata. Evidence of Theileria parva infection was assessed by increased antibody levels as measured in an indirect ELISA assay by the percent positivity (PP) of serum samples relative to a strong positive reference serum. Sero-conversion risks of T. parva were highest in the open-grazing strata. Antibody prevalence in adult cattle and ECF morbidity and mortality risks were also highest in open-grazing strata. While different, all five AEZ-grazing strata were considered to be endemically unstable for ECF. East Coast fever challenge was low in all zero-grazing strata and this challenge is likely to remain low due to continuing intensification of smallholder farming in the central highlands. In the open-grazing strata, there was higher challenge and a greater impact of ECF. ILRI publication no.: 99017

Control of contagious bovine pleuropneumonia: knowledge, attitudes, perceptions and practices in Narok district of Kenya

CBPP is an important transboundary disease in sub-Saharan Africa whose control is urgent. Participatory data collection involving 52 focus group discussions in 37 village clusters and key informant interviews, a cross-sectional study involving 232 households and a post-vaccination follow up involving 203 households was carried out in 2006–2007 in Narok South district of Kenya. This was to investigate knowledge, attitudes, perceptions and practices (KAPP) associated with control of CBPP as well as the adverse post-vaccination reactions in animals in order to advice the control policy. The community perceived trans-boundary CBPP threat to their cattle. They had traditional disease coping mechanisms and were conversant with CBPP prevention and control with 49.8% (95%CI: 42.8–56.7%) giving priority to CBPP control. However, 12.9% (95%CI: 9.0–18.1%) of pastoralists had no knowledge of any prevention method and 10.0% (95%CI: 6.5–14.7%) would not know what to do or would do nothing in the event of an outbreak. Although 43.5% (95%CI: 37.1–50.2%) of pastoralists were treating CBPP cases with antimicrobials, 62.5% (95%CI: 52.1–71.7%) of them doubted the effectiveness of the treatments. Pastoralists perceived vaccination to be the solution to CBPP but vaccination was irregular due to unavailability of the vaccine. Vaccination was mainly to control outbreaks rather than preventive and exhibited adverse post-vaccination reactions among 70.4% (95%CI: 63.6–76.5%) of herds and 3.8% (95%CI: 3.5–4.2%) of animals. Consequently, nearly 25.2% (95%CI: 18.5–33.2%) of pastoralists may resist subsequent vaccinations against CBPP. Pastoralists preferred CBPP vaccination at certain times of the year and that it is combined with other vaccinations. In conclusion, pastoralists were not fully aware of the preventive measures and interventions and post-vaccination reactions may discourage subsequent CBPP vaccinations. Consequently there is need for monitoring and management of post vaccination reactions and awareness creation on CBPP prevention and interventions and their merits and demerits. CBPP vaccine was largely unavailable to the pastoralists and the preference of the pastoralists was for vaccination at specified times and vaccine combinations which makes it necessary to avail the vaccine in conformity with the pastoralists preferences. In addition, planning vaccinations should involve pastoralists and neighbouring countries. As the results cannot be generalized, further studies on CBPP control methods and their effectiveness are recommended

A review of electroencephalograms done at the Kenyatta National Hospital, Nairobi

Background: Electroencephalogram based studies done elsewhere suggest that epileptiform activity originates predominantly from the left cortical hemisphere. There is evidence that partial epilepsies (focal spike and wave epileptiform discharges on tracings) connotes focal;secondary structural cortical dysfunction.Studies seeking similar findings have not been done locally. Objective: To review electroencephalograms (BEGs) done at Kenyatta National Hospital (KNH); looking for various types of epileptiform discharges and their cerebral cortex of origin. Design: Retrospective observational study. Setting: Kenyatta National Hospital, Nairobi, Kenya- from January 1986 to June 2004 Results: A total10431EEG records were reviewed. Ninety Eight percent of referrals for EEG evaluation was for clinical differential diagnosis of epilepsy. AbnormalBEGs comprised 32.2% of the study population. Epileptiform abnormalities (i.e.focal spike and wave,generalized spike and wave and 3Hz spike and wave) discharges accounted for75.2% of all abnormal EEG waveform discharges.Of the epileptiform abnormalities, focal spike and wave discharges comprised 71%. Focal spike and wave discharge implies a possible secondary aetiology of epilepsy.The left cerebral hemisphere was the origin of 49.8% of focal spike and wave epileptiform EEG discharges. Multifocal loci in cerebral cortices (i.e. frontal, temporal and parietal) were the foci of origin of abnormal EEG waveforms in 69.9% of recordings. Conclusion: Focal spike and wave epileptiform discharges, with attendant likely secondary aetiology of epilepsy is predominantly evident in this study. It contrasts findings from western literature.The left cerebral hemisphere is more epileptogenic as is noted in other studies

Plasma and cerebrospinal proteomes from childre with cerebral malaria differ from those of children with other encephalopathies

Journal article published in The Journal of Infectious DiseasesClinical signs and symptoms of cerebral malaria in children are nonspecific and are seen in other common encephalopathies in malaria-endemic areas. This makes accurate diagnosis difficult in resource-poor settings. Novel malaria-specific diagnostic and prognostic methods are needed. We have used 2 proteomic strategies to identify differentially expressed proteins in plasma and cerebrospinal fluid from children with a diagnosis of cerebral malaria, compared with those with a diagnosis of malaria-slide-negative acute bacterial meningitis and other nonspecific encephalopathies. Here we report the presence of differentially expressed proteins in cerebral malaria in both plasma and cerebrospinal fluid that could be used to better understand pathogenesis and help develop more-specific diagnostic methods. In particular, we report the expression of 2 spectrin proteins that have known Plasmodium falciparum–binding partners involved in the stability of the infected red blood cell, suppressing further invasion and possibly enhancing the red blood cell’s ability to sequester in microvasculature.Clinical signs and symptoms of cerebral malaria in children are nonspecific and are seen in other common encephalopathies in malaria-endemic areas. This makes accurate diagnosis difficult in resource-poor settings. Novel malaria-specific diagnostic and prognostic methods are needed. We have used 2 proteomic strategies to identify differentially expressed proteins in plasma and cerebrospinal fluid from children with a diagnosis of cerebral malaria, compared with those with a diagnosis of malaria-slide-negative acute bacterial meningitis and other nonspecific encephalopathies. Here we report the presence of differentially expressed proteins in cerebral malaria in both plasma and cerebrospinal fluid that could be used to better understand pathogenesis and help develop more-specific diagnostic methods. In particular, we report the expression of 2 spectrin proteins that have known Plasmodium falciparum–binding partners involved in the stability of the infected red blood cell, suppressing further invasion and possibly enhancing the red blood cell’s ability to sequester in microvasculature

Activity Budget and Foraging Patterns of Nubian Giraffes (\u3cem\u3eGiraffa camelopardalis camelopardalis\u3c/em\u3e) in Lake Nakuru National Park, Kenya

How animals decide to spend their time has a key impact on their survival and reproduction. These behavioral decisions are shaped by ecological and environmental factors, such as seasonal changes. Foraging patterns show how an animal chooses to forage in its environment as influenced by resource availability, competition, and predation risk. Giraffe activity budget has been investigated in populations across Africa and found to be influenced by body size, diet composition, and sex. The activity budget and foraging patterns of Nubian giraffes vary considerably between ecosystems. The Nubian giraffe, a subspecies of the Northern giraffe species (Giraffa Camelopardalis) is a critically endangered population and occurs only within Kenya, Uganda, Ethiopia, and Southern Sudan. We performed 3 months of behavioral observation on a population of Nubian giraffes in Lake Nakuru National Park, Kenya, to assess seasonal activity budgets and foraging patterns. We found that in the wet and dry seasons giraffe spent approximately the same amount of time (53% and 57%, respectively) foraging. Movement and resting duration decreased slightly from dry to wet seasons 22% to 20% and 25% to 22% respectively. Across both seasons, Vachellia xanthophloea (67%), Maytenus senegalensis (19%), and Solanum incanum (9%) made up the bulk of giraffe\u27s diet. In the dry season, giraffes additionally foraged on Maerua triphylla (2%), Vachellia gerrardi (2%), and Grewia similis (1%); in the wet season, they added Vachellia abyssinica (2%) and Rhus natalensis (2%) to their diet. The most utilized browsing height was 3.5 meters (level 5), below their average height. Giraffes browse at lower heights after they consume the young shoots from the top of the bushes. Overall, seasonality did not appear to influence the Nubian giraffe\u27s activity budget or foraging patterns in LNNP. Planting perennial plants encourage uniform park resource use, boosts forage diversity, and minimizes Vachellia browsing pressure

High boost-ratio bidirectional converter for interfacing low-voltage battery energy storage system to a DC bus

Supply and demand mismatches in renewable energy systems are addressed by integrating battery banks. Selecting battery bank terminal voltage to match DC-bus voltage (350–450 V for single-phase AC loads), necessitates employing battery banks with long-string connections along with their attendant shortcomings. To employ short-string battery banks, high-boost-ratio bidirectional interfaces are required between the DC-bus and battery bank. Current literature lacks a single source where high-boost-ratio converters’ are categorised and their strengths and weaknesses identified. Comprehensive literature review is hence carried out to determine attributes of various high-boost-ratio DC–DC converters and also categorise them. The key attributes of a topology to interface battery storage to a DC-bus are determined. Based on these a bidirectional tapped-inductor boost converter emerges as the best candidate. Moreover, in order to regulate output voltage, voltage-gain versus duty-ratio characteristics should not be very steep. Since battery terminal voltage varies with state-of-charge, closed-loop control is necessary. Converter's small-signal transfer-functions are derived and a two-loop controller to regulate output voltage and inductor current while allowing bidirectional power flow designed. A novel bidirectional passive lossless snubber circuit is employed to clamp the voltage spikes across the active switches, without altering the normal operation of the converter.https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=4475725hj2019Electrical, Electronic and Computer Engineerin

Environmental predictors of bovine Eimeria infection in western Kenya

Eimeriosis is caused by a protozoan infection affecting most domestic animal species. Outbreaks in cattle are associated with various environmental factors in temperate climates but limited work has been done in tropical settings. The objective of this work was to determine the prevalence and environmental factors associated with bovine Eimeria spp. infection in a mixed farming area of western Kenya. A total of 983 cattle were sampled from 226 cattle-keeping households. Faecal samples were collected directly from the rectum via digital extraction and analysed for the presence of Eimeria spp. infection using the MacMaster technique. Individual and household level predictors of infection were explored using mixed effects logistic regression. The prevalence of individual animal Eimeria infection was 32.8% (95% CI 29.9–35.9). A positive linear relationship was found between risk of Eimeria infection and increasing temperature (OR = 1.4, 95% CI 1.06–1.86) and distance to areas at risk of flooding (OR = 1.49, 95% CI 1.17–1.91). There was weak evidence of non-linear relationship between Eimeria infection and the proportion of the area around a household that was classified as swamp (OR = 1.12, 95% CI 0.87–1.44; OR (quadratic term) = 0.85, 95% CI 0.73–1.00), and the sand content of the soil (OR = 1.18, 95% CI 0.91–1.53; OR (quadratic term) = 1.1, 95% CI 0.99–1.23). The risk of animal Eimeria spp. infection is influenced by a number of climatic and soil-associated conditions.</p

Implications on Livelihoods and the Environment of Uptake of Gasifier Cook Stoves among Kenya’s Rural Households

A majority of people in developing countries use biomass energy for cooking and heating due to its affordability, accessibility and convenience. However, unsustainable biomass use leads to forest degradation and climate change. Therefore, this study was carried out in Kwale County, Kenya, on the use of a biochar-producing gasifier cook stove and implications of its uptake on livelihoods and the environment. Fifty households were trained and issued with a gasifier for free. After 2–3 months of gasifier use, a survey was conducted to investigate the implications of its uptake. The direct impacts included reduced fuel consumption by 38%, reduced time spent in firewood collection, reduced expenditure on cooking fuel, diversification of cooking fuels, improved kitchen conditions and reduced time spent on cooking. The potential benefits included income generation, increased food production, reduced impacts on environment and climate change and reduced health problems. Improved biomass cook stoves can alleviate problems with current cooking methods, which include inefficient fuel use, health issues caused by smoke, and environmental problems. These benefits could contribute to development through alleviating poverty and hunger, promoting gender equality, enhancing good health and sustainable ecosystems and mitigating climate change. The study recommends the promotion of cleaner cooking stoves, particularly gasifiers, among households in rural areas while paying attention to user needs and preferences