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Optimization of arsenic(III) and mercury(II) removal from non-competitive and competitive sorption systems onto activated carbon
No full textA Thesis Submitted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Materials Science and Engineering of the Nelson Mandela African Institution of Science and TechnologyHeavy metals exist in the ecosystem both naturally and due to anthropogenic activities and as
recalcitrant pollutants; they are non-biodegradable and cause acute and chronic diseases to
human beings and many lifeforms. As a result, the removal of heavy metals from aqueous
systems using sorbent materials produced from agricultural wastes is one of the new innovative
treatment techniques. In this study, the biosorption and desorption characteristics of heavy
metal ions from non-competitive and competitive aqueous solutions onto hybrid granular
activated carbon produced from maize residues were investigated. The efficient sequestration
of As(III) and Hg(II) ions from both monocomponent and bicomponent synthetic wastewater
was found to show dependence on the physicochemical properties of the biosorbent and the
studied independent biosorption process factors. The regenerated biosorbent could be reused
up to the eighth cycle for the sequestration of As(III) and Hg(II) ions from the synthetic
wastewater without significantly losing its adsorptive properties. The applicability of the
biosorbent synthesized from the maize residues for the simultaneous decontamination of heavy
metals found in real industrial wastewater as a function of several biosorption factors showed
that the biosorbent could competitively decontaminate over 96% of As, Hg, Pb, Cd, and Cr in
100 mL textile wastewater in batch mode. The regeneration of the spent biosorbent using 0.10
M HCl showed that the biosorbent is capable of being recycled and reused severally for the
sequestration of As, Hg, Pb, Cd, and Cr from the textile wastewater and even up to the ten
cycles for a duration of 4 h. The optimization of the competitive removal of As and Hg ions in
the co-existence of other heavy metals in the textile wastewater by the CCD-RSM resulted in
maximum removal efficiencies of 97.72 and 99.99%, respectively. The characterization of the
hybrid granular activated carbon using SEM, TEM, XRD, BET, and FTIR showed that the
biosorbent surface characteristics could facilitate the removal of heavy metals from the non competitive and competitive biosorption media. The main biosorption mechanism of the heavy
metal ions on the biosorbent was mainly chemisorption involving surface complexation.
Therefore, this novel biosorbent is found to be promising and could effectively be employed
for heavy metals remediation in aquatic environments. The outcomes of this study are expected
to make a significant contribution to the design of low-cost and efficient industrial wastewater
treatment systems such as a dynamic batch rector for heavy metal removal using locally
available bio-adsorbents
Influence of land use on the abundance and spatial distribution of mosquito larvae of the Anopheles gambiae complex in a malaria expansion area in northern Tanzania
Get PDFThis research article was published by Hydrobiologia / Volume 851/2024In many countries, successful control of larval mosquito populations for malaria control is still hindered by poor knowledge of preferred breeding habitats and natural factors limiting larval abundance. In Africa, preferred breeding habitats for malaria mosquitoes vary regionally and for many regions, they are still not well known. Moreover, variables that limit abundance of larvae of malaria mosquitoes are still ambiguous and impacts of surrounding land use practices are unclear. To study this, we sampled mosquito larvae from 164 small ground habitats (SGHs) in the lake Manyara basin (LMB) in northern Tanzania, a malaria expansion area with diverse land use types. We found that Anopheles gambiae s.l. was the only malaria mosquito breeding in SGHs in the region and its abundance was positively affected by turbidity and proximity to human dwellings. SGHs appear to be the major breeding sites for An. gambiae s.l. in the LMB despite the presence of larger temporary ponds which support negligible numbers of this species. In this region, we recommend that control of malaria via control of population of larval An. gambiae s.l. should prioritize SGHs to optimize use of limited resources and avoid damage to the environment by targeting unimportant habitats
Sustaining indigenous Maasai Alalili silvo-pastoral conservation systems for improved community livelihood and biodiversity conservation in East African rangelands Elkana HezronID*, Issakwisa B. N
Get PDFThis research article was published by PLOS ONE, in 2024Alalili system is one among the fewest remnant African indigenous and local knowledge systems that is traditionally practiced by Maasai pastoral communities to conserve certain portions of rangeland resources such as pastures and water for subsequent grazing during dry seasons. Despite its existence, East African rangelands face diverse threats from tenure security, unsustainable practices, climate, and land-use change that are notably endangering the biodiversity, livelihoods, and ecosystems in the landscape. Like other indigenous conservation systems, the sustainability of Alalili systems is being threatened, as Maasai communities are in transition due to continuous socio-cultural transformations coupled with increased livestock and human populations. We aimed to capture and document the existing occurrence and potential of Alalili systems as a pathway to improve resilience and sustain both biodiversity conservation and community livelihoods in rangeland areas of northern Tanzania. A cross-sectional research design was applied with the adoption of both purposive and stratified random sampling techniques to distinctively characterize the Alalili systems by land use and tenure types. Our results identified the existence of both communal and private Alalili systems. Their sizes varied significantly across types (t = 4.4646, p < 0.001) and land uses (F = 3.806, df = 3, p = 0.0123). While many (82%) of these Alalili systems are found in the communal land, our observations show a re-practice of Alalili systems in the private land is considered largely a re-emerging strategy for securing pastures in the face of local and global change. More than half (73%) of Alalili systems were found within game-controlled areas with little representation (about 8%) in non-protected land. Therefore, their sustainability is threatened by anthropogenic and climatic pressures, making their persistence more vulnerable to extinction. We recommend mainstreaming these practices into core pasture production and management areas, facilitating their reinforcement into policy and practices
A Review on Degradation Improvement of Sisal Fiber by Alkali and Pozzolana for Cement Composite Materials
Get PDFThis research article was published by Journal of Natural Fibers, in 2024Sisal fiber employment in concrete improves its post-crack strength, but sisal
fiber degrades due to moisture and cement mineralization. Many researchers
used alkaline and pozzolanic techniques to treat sisal fiber in cement com-
posite materials. However, which treatment method is most effectively used
to modify sisal fiber for sustainable use in cementing materials has yet to be
well known. Therefore, this review highlights the effect of alkaline and
pozzolanic materials on sisal fiber treatment. The review of various studies
found employment of 1–1.5% of treated sisal fiber by alkaline or pozzolana
reduces workability and improves the mechanical properties, especially as
many authors found the treatment of sisal fiber by pozzolanic material
averagely improves compressive strength and splitting tensile strength of
cementing materials by 21.75% and 36.53%, while alkaline treatment 12.83%
and 14.92% respectively, compared to control mixture. Besides these, many
studies found the treatment of sisal by either alkaline or pozzolana signifi-
cantly lessens water absorption capacity, improves the thermal resistivity of
the fiber, improves fiber adhesion with the matrix, makes rougher micro-
structure of fiber surface. However, many studies reported alkaline treatment
to have drawbacks in the disposal of alkaline chemicals that increase envir-
onmental pollution, at high concentrations cause fiber deterioration, and
chemical production cost.
摘要
在混凝土中使用Sisal纤维提高了其裂缝后强度，但由于水分和水泥矿化而
降解. 许多研究人员使用碱性和火山灰技术处理水泥复合材料中的剑麻纤
维. 然而，哪种处理方法最有效地用于改性剑麻纤维，使其可持续地用于
胶结材料，目前尚不清楚. 因此，本文着重介绍了碱性和火山灰材料对剑
麻纤维处理的影响. 对各种研究的回顾发现，使用1-1.5%的经碱性或火山
灰处理的剑麻纤维可降低工作性并提高机械性能，特别是许多作者发现，
与对照混合物相比，用火山灰材料处理剑麻纤维平均可提高21.75%和
36.53%的胶凝材料抗压强度和劈拉强度，而碱性处理分别可提高12.83%
和14.92%. 除此之外，许多研究发现，用碱性或火山灰处理剑麻可以显著
降低吸水能力，提高纤维的热阻，提高纤维与基体的附着力，使纤维表面
微观结构更加粗糙. 然而，许多研究报告称，碱性处理在处理碱性化学品
方面存在缺陷，这会增加环境污染，导致纤维在高浓度下变质，化学品生
产成本
Review of the Current Status on Livestock Abortigenic Diseases Surveillance in Africa and Asia.
Get PDFThis article was published on March 8, 2024, and its Dio is doi:10.20944/preprints202403.0464.v. It is also available at the Nelson Mandela institute repositoryIntroduction: Livestock abortigenic agents, are microorganisms that lead to
premature foetal death and expulsion before completion of the gestation period, are common in
Africa and Asia. Abortion events cause economic losses by lowering reproduction (and hence
herd/flock sizes) and effects on milk production. Despite the importance of livestock production for
food security and livelihoods of millions of the world’s poorest communities, very little is known
about the scale, magnitude or causes of livestock abortion in Africa. The aim of this review was to
determine the current status of the burden of livestock abortion and surveillance measures adopted
for livestock abortigenic pathogens in Africa and Asia, and to explore feasible surveillance
technologies. Methodology: A systematic literature search was conducted using Preferred
Reporting of Systematic Reviews and Meta-analyses (PRISMA) guidelines in four databases for
studies published between 1 Jan 1990 and 31 July 2021 that reported epidemiological surveys of
livestock abortigenic pathogens in cattle, goats and sheep in Africa and Asia including; Brucella spp.,
Neospora caninum, Toxoplasma gondii, Rift valley fever virus, Coxiella burnetii, Chlamydia, Leptospira and
Bovine viral Diarrhoea Virus. A meta-analysis was used to estimate the species-specific prevalence of
the abortigenic diseases and the region where they were detected. Results: In the systematic
literature search, 48 full papers were included which in total included 50 species-specific
surveillance reports from Africa and 19 from Asia. Adjusted median seroprevalence calculations
estimated Brucella at 6.85% (range 1.2-11.6) of 9071 sheep, 3.35% (range 0.90-5.40) of 17,007 goats,
8.95% (range 0.50-63.60) of 171,733 cattle, Neospora at 6.80% (range 6.80 -6.80) of 555 sheep, 10.80
(range 10.80-10.80) of 185 goats, 12.65% (range 3.40- 25.60) of 3775 cattle, Toxoplasma at 27.50% (range
1.40 – 75.90) of 2284 sheep, 32.0% (range 20.00- 64.80) of 1226 goats, 7.50% (range 7.50 - 7.50) of 174
cattle, Coxiella at 9.20 (range 9.20 – 9.20) of 184 sheep, 24.20% (range 24.20-24.20) of 91 goats, 13.80%
(range 13.80-13.80) of 217 cattle, Rift valley fever virus at 7.70 (2.40-40.00) of 874 sheep, 20.95 (range
2.50-40.00) of 547 goats, 7.45% (range 3.60-11.30) of 309 cattle, Bovine viral diarrhea virus at 78.90
(range 78.90 – 78.90) of 398 cattle, Leptospira at 70.50 (range 70.50 – 70.50) of 373 cattle and
Chlamydia at 6.60 (6.60-6.60) of 803 sheep. We found that in most studies, 45 (89%) used serological
surveys, 1 (2%) used molecular and 1 (2%) reported to have used Mobile-phone based surveillance
approach. Three studies (6.25%) of the 48 included were embedded in the national surveillance
programs of the respective countries they were conducted, the majority 89% were stand-alone cross sectional studies. Conclusion: In conclusion, livestock abortigenic pathogens are still a burden in
many African and Asian countries
Database Privacy: Design of User Privacy Preserving Central Bank Digital Currency: A Case of Tanzania
Get PDFThis research article was published by INDIAN JOURNAL OF SCIENCE AND TECHNOLOGY,In 2024Objectives: This work aims to contribute towards Tanzanian Central Bank
Digital Currency (CBDC) users’ privacy preservation. It proposes the design of
a privacy preserving CBDC which might be issued by Tanzania’s Central Bank
(CB), the Bank of Tanzania (BoT), which is currently in CBDC research phase. The
work also aims to contribute to literature, the CBDC research being done by
BoT, other CBs and CBDC stakeholders around the world. Methods: By using
the Design Science Research (DSR) methodology, a privacy preserving CBDC
design suitable for Tanzania was proposed, demonstrated and evaluated. This
is the result of existing literature showing that different countries have different
CBDC designs due to their differences in contexts and purposes for CBDC
issuance. This consequently emphasized the fact that a CBDC design should
not be treated as a one-size fits all solution. Findings: As opposed to the
existing general and other country specific CBDC designs, we proposed a
privacy preserving CBDC design suitable for Tanzania by consulting literature
and taking into consideration the Tanzanian context. The design appears to
be promising Tanzanian CBDC users’ privacy preservation though further work
needs to be done. The work should not only be on practical evaluation of
the proposed design but also on other factors impacting the success of CBDC
projects. This will consequently further increase the success probability of
CBDC projects, hence the potential for practical realization of CBDC project
benefits. Novelty: Existing literature has shown that, considering the countries’
differences in context and CBDC issuance purposes, CBDC design should
not be treated as a generic solution thereby obliging the need for country-
specific CBDC designs. Consequently, the privacy preserving CBDC design
suitable specifically for Tanzania consists of and provides an outline of privacy
preserving interactions among the identified key Tanzanian CBDC participants
or actors. The actors are the BoT, the intermediaries (i.e., other banks and
payment service providers), Tanzania’s National Identification Authority (NIDA),
financial transactions violation detection engine, and the expected CBDC users
Flea infestation of rodent and their community structure in frequent and non-frequent plague outbreak areas in Mbulu district, northern Tanzania
Get PDFThis research article was published by ELSEVIER,2024Understanding rodent-ectoparasite interactions and the factors driving them is important in understanding the
epidemiology of diseases involving an arthropod vector. Fleas are the primary vector for Yersinia pestis, the
bacteria that causes plague and monitoring of flea population is essential for planning the potential mitigation
measures to prevent the disease outbreak. In this study, we investigated flea abundance, community structure
and the potential factors driving flea infestation in areas with frequent (persistent) and non-frequent plague (non-
persistent) outbreaks. We collected fleas from captured rodents in two villages with both forest and farm hab-
itats. We found 352 fleas belonging to 5 species with Dinopsyllus lypusus the most abundant overall (57.10%) and
Ctenophthalmus spp. the lowest (1.70%). There were no significant differences of flea abundance between study
localities, habitats and seasons (p > 0.05) but, flea infestation was significantly positively associated with the
persistent locality and with the short rain season (p < 0.05). Further, flea abundance increased significantly with
rodent body weight (p < 0.05). Furthermore, we found fleas broadly structured into two communities varying
between the dry, long rain and short rain seasons. These findings have important implications for public health,
as they may be used to assess and control the risks of plague transmission and other flea borne diseases in the
foci
Review of the Current Status on Livestock Abortigenic Diseases Surveillance in Africa and Asia
Get PDFThis article was published in the Journals Sustainability Volume 16, Issue 5, 2024Introduction: Livestock abortigenic agents, which are microorganisms that lead to
premature foetal death and expulsion before completion of the gestation period, are common in
Africa and Asia. Abortion events cause economic losses by lowering reproduction (and hence
herd/flock sizes) and effects on milk production. Despite the importance of livestock production for
food security and livelihoods of millions of the world’s poorest communities, very little is known
about the scale, magnitude or causes of livestock abortion in Africa. The aim of this review was to
determine the current status of the burden of livestock abortion and surveillance measures adopted
for livestock abortigenic pathogens in Africa and Asia, and to explore feasible surveillance
technologies. Methodology: A systematic literature search was conducted using Preferred
Reporting of Systematic Reviews and Meta-analyses (PRISMA) guidelines in four databases for
studies published between 1 Jan 1990 and 31 July 2021 that reported epidemiological surveys of
livestock abortigenic pathogens in cattle, goats and sheep in Africa and Asia including; Brucella spp.,
Neospora caninum, Toxoplasma gondii, Rift valley fever virus, Coxiella burnetii, Chlamydia, Leptospira and
Bovine viral Diarrhoea Virus. A meta-analysis was used to estimate the species-specific prevalence of
the abortigenic diseases and the region where they were detected. Results: In the systematic
literature search, 48 full papers were included which in total included 50 species-specific
surveillance reports from Africa and 19 from Asia. Adjusted median seroprevalence calculations
estimated Brucella at 6.85% (range 1.2-11.6) of 9071 sheep, 3.35% (range 0.90-5.40) of 17,007 goats,
8.95% (range 0.50-63.60) of 171,733 cattle, Neospora at 6.80% (range 6.80 -6.80) of 555 sheep, 10.80
(range 10.80-10.80) of 185 goats, 12.65% (range 3.40- 25.60) of 3775 cattle, Toxoplasma at 27.50% (range
1.40 – 75.90) of 2284 sheep, 32.0% (range 20.00- 64.80) of 1226 goats, 7.50% (range 7.50 - 7.50) of 174
cattle, Coxiella at 9.20 (range 9.20 – 9.20) of 184 sheep, 24.20% (range 24.20-24.20) of 91 goats, 13.80%
(range 13.80-13.80) of 217 cattle, Rift valley fever virus at 7.70 (2.40-40.00) of 874 sheep, 20.95 (range
2.50-40.00) of 547 goats, 7.45% (range 3.60-11.30) of 309 cattle, Bovine viral diarrhea virus at 78.90
(range 78.90 – 78.90) of 398 cattle, Leptospira at 70.50 (range 70.50 – 70.50) of 373 cattle and
Chlamydia at 6.60 (6.60-6.60) of 803 sheep. We found that most studies, 45 (89%) used serological
surveys, 1 (2%) used molecular and 1 (2%) reported to have used Mobile-phone based surveillance
approach. Three studies (6.25%) of the 48 included were embedded in the national surveillance
programs of the respective countries they were conducted, majority 89% were stand-alone cross-
sectional studies. Conclusion :In conclusion, livestock abortigenic pathogens are still a burden in
many African and Asian countries
Flea infestation of rodent and their community structure in frequent and non-frequent plague outbreak areas in Mbulu district, northern Tanzania
Get PDFThis Research article was Published by Elsevier, 2024Understanding rodent-ectoparasite interactions and the factors driving them is important in understanding the
epidemiology of diseases involving an arthropod vector. Fleas are the primary vector for Yersinia pestis, the
bacteria that causes plague and monitoring of flea population is essential for planning the potential mitigation
measures to prevent the disease outbreak. In this study, we investigated flea abundance, community structure
and the potential factors driving flea infestation in areas with frequent (persistent) and non-frequent plague (non-
persistent) outbreaks. We collected fleas from captured rodents in two villages with both forest and farm hab-
itats. We found 352 fleas belonging to 5 species with Dinopsyllus lypusus the most abundant overall (57.10%) and
Ctenophthalmus spp. the lowest (1.70%). There were no significant differences of flea abundance between study
localities, habitats and seasons (p > 0.05) but, flea infestation was significantly positively associated with the
persistent locality and with the short rain season (p < 0.05). Further, flea abundance increased significantly with
rodent body weight (p < 0.05). Furthermore, we found fleas broadly structured into two communities varying
between the dry, long rain and short rain seasons. These findings have important implications for public health,
as they may be used to assess and control the risks of plague transmission and other flea borne diseases in the
foci
Web-based freight forwarding system for logistics management: case study of Trueline Africa Limited in Kampala, Uganda
Get PDFFreight forwarding sector is moving from manual handling of freights to electronic freight
because of the ever-changing needs of technologies. The study aimed to develop a freight
forwarding web-based information system to manage logistics by automating manual processes
that enable electronic data exchange, accelerate processes, improve communication, facilitate
easy access to and retrieval of documents, enhance customer service, and drive efficiency and
profitability. In order to collect the data, the author employed both qualitative and quantitative
techniques, as well as the Extreme Programming (XP) system development methodology. The
developed system was tested and assessed using unit testing, integrated testing, and system
testing. By creating a survey questionnaire and distributing it to the system's end users, the
system was validated using the TAM with Trust. The verdicts showed that perceived usefulness,
perceived ease of use, and system acceptance are all influenced by trust, which is believed to
be a key component. Furthermore, it has been found that system usage and perceived utility
are greatly enhanced by perceived ease of use. The creation of this system has reduced errors,
work overload, operating expenses, and the likelihood of on-time item delivery. The author
advises using the Global Positioning System (GPS) for cargo tracking and visibility in
additional investigations, as well as integrating it with customs systems for compliance checks
and guaranteeing adherence to legal standards to lower the danger of fines and delays