Levels and spatial distribution of heavy metals in Lake Chilwa Catchment, Southern Malawi

The aim of this study was to assess the levels and distribution of heavy metals in Lake Chilwa and its catchment, and to understand the associated level of pollution. Water and sediment samples were collected from the lake and main inflowing rivers. A total of 23 surface water samples were sampled and analysed for pH, EC, Cu, Cr, Zn, Cd, Pb, As and Hg. Conductivity and pH were measured on-site with a Hanna portable multi meter, while metals were analysed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The pH was found within the alkaline range (7.87-10.13), while conductivity ranged from 97-390μS/cm. The following metals were detected in the water samples; Zn (6.24–1168.70 μg/L), Cu (BDL–47.83 μg/L), Pb (BDL–49.94 μg/L), Cr (0.22–33.05 μg/L), Ni (0.40–8.20 μg/L) and Cd (BDL–0.53 μg/L). Hg and As were not detected in all sampling locations. Strong positive correlations were observed between Cd and Pb (r = 0.70), Cu and Zn (r = 0.70), while Cd and Ni (r = 0.50), Pb and Ni (r = 0.41) showed mild correlations, suggesting similar sources of input. Sediments were sampled from 2 locations in the lake and the following metals were detected; Zn (66.13 mg/Kg), Pb (7.74 mg/Kg), Ni (35.39 mg/Kg), Cu (20.02 mg/Kg), Cr (54.81 mg/Kg) and As (1.0 mg/Kg). Mercury and arsenic were not detected from both sampling locations. The heavy metal pollution index ranged from 2.24 to 114.45. All points except Kachulu harbour had values far below the critical pollution index value of 100. The values observed were well below the tolerable limits recommended by the World Health Organisation (WHO) standard for potable water, except for Pb at Kachulu Bay (P19) which was above the limit. Concentrations of the metals in the rivers were low upstream and increased downstream. Highest values for most of the elements were observed from the lake. Though levels are low now, the persistent and cumulative properties of these elements would render them unsafe in the near future if proper controls are not enforced.Keywords: Heavy metals, Lake Chilwa, Water pollution, Water qualit

"I don't hesitate to use the left-over antibiotics for my child" practices and experiences with antibiotic use among caregivers of paediatric patients at Zomba central hospital in Malawi

BackgroundInappropriate use of antibiotics is among the major causes of the global emergency of antibiotic resistance among children. The problem of inappropriate use of antibiotics among children is of special concern because they are still developing immunological systems, hence they are susceptible to many infectious diseases. As such, they receive a considerable disproportional amount of antibiotics which exposes them to antibiotic resistance. This study explored the lived experiences of caregivers of children under the age of five years on the use of antibiotics at Zomba central hospital.ObjectiveThe main aim of this study was to explore the lived experiences of caregivers of children under the age of five years on antibiotic usage at Zomba Central Hospital, Zomba-Malawi.MethodologyThis was a descriptive qualitative study with a phenomenological approach to explore the lived experience of caregivers of paediatric patients on antibiotic usage from May 2019 to July 2020. The study used interview guides to conduct in-depth interviews with 16 caregivers and purposive sampling was used to select the participants from the children's ward. All interviews were audio-recorded and qualitative data was transcribed verbatim and thematically analysed manually to extract major themes and concepts on the subject matter.ResultsCaregivers had little knowledge about antibiotic use and its resistance. most caregivers use the antibiotics inappropriately through self-medication, use of left-over antibiotics, buying antibiotics without prescription, and sharing of antibiotics.ConclusionBased on the findings of this study, investment in public awareness and organising community-led interventions in antibiotic use related information is key to improve the quality use of antibiotics. The Government should focus on promoting interventions that lessen the indiscriminate use of antibiotics among the caregivers. Stringent laws need to be enforced by the government to restrict the access of antibiotics to parents without a prescription

Evaluation of the bright greenish yellow fluorescence test as a screening technique for aflatoxin-contaminated maize in Malawi

The bright greenish yellow fluorescence (BGYF) test has been used with varying success in screening for aflatoxins in maize. This test was applied to 180 maize samples collected from different markets within 12 districts of Malawi in order to evaluate its performance against high performance liquid chromatographic analysis. The number of BGYF grains in 2.5 kg unground samples ranged from 0 to 35 and about 49% of all tested samples had aflatoxin concentrations ranging from 1 to 382 mu g/kg. A total of 65 (36%) of the examined unground samples showed no BGYF. The European Commission recommends a false negative rate of less than 5% for a screening technique to be acceptable. In this study, four BGYF grains per 2.5 kg unground maize sample successfully indicated an aflatoxin contamination of >10 mu g/kg (10 mu g/kg being the maxium tolerable level proposed by the Common Market for Eastern and Southern Africa), with a 4.4% false negative rate. In this case, the amount of confirmatory analyses would be reduced by 63%, if the BGYF test was employed as a screening method. The screening technique therefore offers a practical tool for Malawi and possibly for the Sub-Saharan region

Opportunities and challenges associated with municipal solid waste disposal: A case study of Malawian cities

Malawi, as a developing country, faces serious environmental and health challenges associated with waste generation, transportation and disposal. Currently, available waste services rendered to the public are not sufficient to accommodate all residents in all cities due to rapid urban population growth. This paper highlights challenges that hinder effective municipal solid waste handling in Malawi. The literature survey has shown that existing dumping sites are in a bad state and do not meet the required standards, thereby posing danger to the diversity, ecological systems, environment and public health. Waste reduction through recycling of organic wastes into farmyard manure, plastic and metals exist on a small scale among some households and they are getting income. The challenges associated with municipal waste management are inadequate funding, lack of disposal infrastructure, weak enforcement of rules and regulations and the use of inappropriate vehicles for waste transportation. The activities such as the conversion of waste to energy, civic educating of residents, promoting recycling activities, expanding waste collection services to all residents and opening new engineered landfills and sufficient funding of municipalities would upscale waste management process

Copper oxide nanoparticles-loaded zeolite and its characteristics and antibacterial activities

In the present work, a simple and green co-precipitation method was used to prepare copper oxide-zeolite nanocomposites (CuO-zeolite NCs). The weight ratio (1, 3, 5, 8 and 10 wt%) of CuO nanoparticles (NPs) loaded into zeolite was investigated to obtain the optimum CuO distribution for antibacterial activities. The prepared CuO-zeolite NCs were characterized by ultraviolet-visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), and energy dispersive X-ray fluorescence spectrometry (EDXRF). The transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) revealed a uniform surface morphology of the CuO-zeolite NCs. The UV–vis spectrum of NCs showed absorption peaks between 230 and 280 nm for nano-CuO in the XRD patterns, and new peaks appeared between (36.56°–38.83°) related to the CuO. At weight ratio less than 10 wt%, the CuO nanoparticles loaded to the zeolite exhibited spherical shapes with average particle diameter of 6.5 nm measured by TEM and XRD. Antibacterial activities were tested against Gram-negative and Gram-positive bacteria. The obtained results showed that, CuO-zeolite NCs with 8 wt% CuO nanoparticles had the highest antibacterial activities against Bacillus Subtilis B29 and Salmonella Choleraesuis ATCC 10708, which can be attributed to the good dispersion of CuO NPs on the zeolite surface

Development of drug delivery systems based on layered hydroxides for nanomedicine

Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life

Synthesis and characterization of low-cost activated carbon prepared from Malawian baobab fruit shells by H3PO4 activation for removal of Cu(II) ions: equilibrium and kinetics studies

Abstract In this study, low-cost activated carbon (AC) prepared from baobab fruit shells by chemical activation using phosphoric acid was evaluated for the removal of Cu(II) ions from aqueous solution. The prepared activated carbon samples were characterized using N2-adsorption–desorption isotherms, SEM, FTIR, EDX and XRD analysis. The sample activated at 700 °C was chosen as our optimized sample because its physicochemical properties and BET results were similar to those of a commercial sample. The N2-adsorption–desorption results of the optimized sample revealed a BET surface area of 1089 m2/g, micropore volume of 0.3764 cm3/g, total pore volume of 0.4330 cm3/g and pore size of 1.45 nm. Operational parameters such as pH, initial copper concentration, contact time, adsorbent dosage and temperature were studied in a batch mode. Equilibrium data were obtained by testing the adsorption data using three different isotherm models: Langmuir, Freundlich and Dubinin–Radushkevish (D–R) models. It was found that the adsorption of copper correlated well with the Langmuir isotherm model with a maximum monolayer adsorption capacity of 3.0833 mg/g. The kinetics of the adsorption process was tested through pseudo-first-order and pseudo-second-order models. The pseudo-second-order kinetic model provided the best correlation for the experimental data studied. The adsorption followed chemisorption process. The study provided an effective use of baobab fruit shells as a valuable source of adsorbents for the removal of copper ions from aqueous solution. This study could add economic value to baobab fruit shells in Malawi, reduce disposal problems, and offer an economic source of AC to the AC users

Wastewater Clarification and Microbial Load Reduction Using Agro-Forestry and Agricultural Wastes

Five agro-wastes, namely: cassava peels, Irish potato peels, Jatropha curcas seeds, Moringa oleifera seeds and rice husks were investigated as plant-based coagulants for turbidity and microbial load removal from sewage wastewater. Moringa oleifera and Jatropha curcas seeds before usage were defatted with 95% ethanol and the active coagulating component was extracted with 1.0 M NaCl. For the other three agro-wastes, their ashes were evaluated for turbidity and microbial load removal. The ash was prepared through pyrolysis of the raw biomass at a temperature of 800 °C for 3 h. The effect of pH, coagulant dose, settling time on turbidity reduction was investigated using sewage wastewater with an initial turbidity of 464.11 ± 0.13 NTU. The microbial load removal of the coagulants was investigated using three media onto which 1 mL of treated wastewater was poured and streaks were made using sterile swabs and then incubated at 37 °C for 24 h. Jatropha curcas and rice husks ashes exhibited the maximum turbidity reduction of 97.0% and 95.0%, respectively at pH 2, whereas for Moringa oleifera, the highest turbidity removal (96.0%) was achieved between pH 6 and 10. Additionally, it was observed that the electrical conductivity and total dissolved solids of the clarified wastewater increased as the doses were increased for all coagulants due to inorganic salts contained in seeds. The microbial load understudy was successfully reduced in wastewater clarified with Jatropha curcas and rice husks ashes, contrary to Moringa oleifera that increased microbial load content. The raw biomass and ashes for cassava and Irish potato peels could not clarify sewage wastewater. The results from this study have demonstrated that plant-based materials used performed effectively in turbidity and bacteria removal from sewage wastewater. Keywords: Domestic Wastewater; Clarification; Agro-Wastes; Turbidity; Microbial Loa

A synchrotron radiation study of the hydrothermal synthesis of layered double hydroxides from MgO and Al2O3 slurries

The hydrothermal reaction of slurries containing MgO and Cp3 alumina has been investigated in situ using energy dispersive X-ray diffraction (EDXRD). A range of temperatures (100, 150, 180 and 240 °C) were studied. Kinetic data for the formation of the hydrotalcite-like Mg-Al layered double hydroxide (LDH) have been determined. At 100 °C the LDH is the predominant phase that is formed but at higher temperatures the impurity phases brucite and boehmite become more significant. The rate of reaction increases with temperature in agreement with Arrhenius behaviour and the LDH growth curves exhibit sigmoidal kinetics. The rate of formation of the LDH phase was found to be approximately equal to the rate of consumption of MgO, indicating that the mechanism of LDH formation is unlikely to proceed via a long-lasting intermediate phase. © The Royal Society of Chemistry 2007