Biosorption of fluoride ion from water using the seeds of the cabbage tree (Moringa stenopetala)

Conventional water treatment technologies for the removal of fluoride ion may not be feasible for developing countries due to their high investment and operational costs. The aim of this study was therefore, to investigate the fluoride biosorption potential of the seeds of the cabbage tree (Moringa stenopetala). The influence of Moringa dosage, pH, contact time, and initial concentration of fluoride ion was investigated. The maximum fluoride sorption capacity was found to be 1.32 mg.g-1 of dry weight of Moringa seeds at a biomass dosage of 2 g L-1, pH 7.00, initial fluoride ion concentration of 10 mg.L-1 and a contact time of 60 min. The fluoride level was reduced from 10 to 3.4 mg L-1. The adsorption of fluoride ion onto Moringa powder was best described by the pseudo-second-order kinetic model (R2 = 0.99). Theadsorption equilibrium data have been fitted well to Langmuir as well as Freundlich adsorption models (R2≥0.97 for both models). The distribution constant (Kd) and maximum adsorption capacity (Bmax) were significantly influenced by the amount of Moringa and equilibrium fluoride ion concentration (p<0.05). The desorption tests indicated that only 20% of the initially bound fluoride ion was regenerated, while the remaining 80% were bounded with the Moringa powder. This suggests that chemisorption was the possible mechanism of fluoride removal.Key words: Biosorption, chemisorption, desorption, fluoride, isotherm, Moringa stenopetala

Nasal and Hand Carriage Rate of Staphylococcus aureus among Food Handlers Working in Jimma Town, Southwest Ethiopia

BACKGROUND: Food handlers have been recognized to play a major role in the transmission of food borne diseases, contributing significantly to the global incidence and burden of the diseases. This study, therefore, aimed to assess the nasal and hand carriage of Staphylococcus aureus among food handlers in Jimma Town.METHODS: A community based cross sectional study was conducted from February to May 2017. Swab specimens from nasopharyngeal and hands of food handlers working in food establishments were collected for isolation and identification of S. aureus using standard bacteriological methods. Antimicrobial susceptibility test was done using disc diffusion method. Associations of selected variables for S. aureus colonization were determined using SPSS version 20 with p ≤ 0.05 taken as statistically significant.RESULTS: Among the 300 food handlers working in hotels and restaurants in Jimma Town, 86(28.7%) were colonized by S. aureus. The frequency of isolation of S. aureus from nose, hand and both parts (nose and hand) were 27(9%), 34(11.3%) and 25(8.3%), respectively. There was strong association (P=0.00336) between carriage rate of S. aureus and food handlers’ job category. The majority (90.7%) of the isolates were resistant to Penicillin and Ampicillin. Increased levels of sensitivity were observed against Ciprofloxacin (96.5%), Cefoxitin (95.3%) and Amoxicillin- Clavulanic Acid (94.2%).CONCLUSIONS: This study revealed a high prevalence of S. aureus carriers among food handlers and high antibacterial resistance towards commonly prescribed drugs, justifying the screening of food handlers to detect and treat carriers and protect restaurant customers from staphylococcal food poisoning.

Effect of human-induced environmental changes on bird diversity and abundance in natural wetlands of Southwest Ethiopia

The diversity and abundance of wetland birds have been threatened by increasing anthropogenic activities during recent decades. The objective of this study was to determine the effect of human-induced disturbance on bird species richness and abundance of natural wetlands in southwest Ethiopia. Bird surveys were performed at 56 locations during both the wet and dry seasons in 2010 and 2011. Generalized linear modeling (G) was used to correlate species richness with environmental variables. It was found that wetlands with low human disturbance were characterized by a higher richness (n > 10) of wetland dependent specialist birds (depending completely on wetlands for food and nesting) than the highly disturbed wetlands. However, for wetland-associated birds (those able to nest and feed in wetlands as well as in other habitats), there was no significant difference (P = 0.31) in species richness between disturbed and non-disturbed wetlands. The abundance of wetland dependent specialist birds was significantly affected (P < 0.001) by human disturbance, whereas the abundance of wetland associated birds was not (P = 0.39). Fifty-three percent of the variation in species richness of wetland dependent birds was explained by a combination of water depth, sludge depth, conductivity, chlorophyll a, total phosphorus, human disturbance and vegetation cover. It is recommended that anthropogenic activities should be minimized and controlled in and around these wetlands to conserve biodiversity

Using macroinvertebrates and birds to assess the environmental status of wetlands across different climatic zones in Southwestern Ethiopia

We investigated the variation in macroinvertebrate and bird fauna of 12 different freshwater wetlands located in three different climatic zones of southwestern Ethiopia. Data on macroinvertebrates, birds, physico-chemical water quality variables, human disturbance and vegetation cover were collected from 62 sampling sites during the dry and wet season of 2015. Generalized linear mixed models (GLMMs) were used to identify the most important variables explaining the variation in macroinvertebrates and birds. Twenty four percent of the variation in macroinvertebrate richness was explained by a combination of vegetation cover and dissolved oxygen, whereas 34% of the variation in macroinvertebrate abundance was explained by a combination of dissolved oxygen saturation, electric conductivity, total phosphorus and vegetation cover. A combination of water depth, dissolved oxygen, human disturbance and macroinvertebrate abundance explained about 34% and 31% of variation in bird species richness and abundance, respectively. Richness and abundance of macroinvertebrate and wetland dependent birds were significantly (P<0.05) different between wetlands. When investigating the ecological status of wetlands, local environmental conditions of wetland should be taken into account for the development of wetland conservation strategies

Water quality assessment of streams and wetlands in a fast growing East African city

The combination of rapid urbanization, industrialization, population growth, and low environmental awareness poses a major threat to worldwide valuable freshwater resources, which provide important ecosystem services to humans. There is an urgent need to monitor and assess these resources, as this information is indispensable for sustainable decision -making and management. In this context, we analyzed the chemical and ecological water quality of the riverine environment of a fast growing city in Southwest Ethiopia for which we proposed possible remediation options that were evaluated with an empirical model. The chemical and ecological water quality was assessed at 53 sampling locations using the oxygen Prati index and the ETHbios, which is a biotic index based on macroinvertebrates. In addition, a microbiological analysis was performed to estimate the degree of fecal contamination. Finally, we analyzed the relationship between the oxygen content and the organic pollution to simulate the effect of organics removal from waste streams on the chemical water quality. Our results showed that the average values for dissolved oxygen (4.2 mg DO.L-1) and nutrients (0.9 mg oPO(4)(3-) . L-1 and 12.8 mg TAN.L-1) exceeded international standards. Moreover, high turbidity levels revealed that land erosion is a severe problem in the region. Along the rivers, a significant increase in oxygen consumption and in nutrient concentrations was observed, indicating organic pollution originating from different diffuse and point sources of pollution. The lack of proper sanitation also led to exceedingly high abundances of fecal coliforms in the surface water (>320 MPN. mL(-1)). However, fecal contamination was strongly reduced (>92%) after the polluted river water passed Boye wetland, indicating the purification potential of natural wetlands and the importance of conserving and protecting those ecosystems. The simulation results of the model showed that water quality could be substantially improved if municipal, industrial, and institutional wastewater was efficiently collected and transported to a treatment facility. Waste stabilization ponds and constructed wetlands are highly promising techniques, as they provide a cheap, effective, reliable, and sustainable way to purify wastewater. It is advised that the environmental awareness of the people via sensitization, education, and law enforcement is increased, as this is essential for sustainable development

Sediment and nutrient retention capacity of natural riverine wetlands in Southwest Ethiopia

Although wetlands in temperate regions have been studied for their pollutant remediation potential, the sediment and nutrient retention capacity of natural wetlands in tropical environments remains understudied. In this study, a mass balance approach was used to estimate the amount of sediment and nutrients retained at 40 different study sites located in four natural riverine wetlands in Southwest Ethiopia. Awetu and Boye wetlands retained a substantial amount of total suspended solids (TSS) and nutrients whereas Kofe and Kito wetlands had a net release. Overall, the amount of TSS retained by the four wetlands was estimated to be 6266.5 kg/ha/day. On the other hand, the net retention of Total Organic Nitrogen (TON) and Total Phosphorous (TP) was estimated to be 37.6 kg/ha/day and 40.9 kg/ha/day, respectively. A stepwise multiple regression analysis revealed that anthropogenic activities such as farming, grazing, waste dumping and clay mining were the main variables that negatively affected the retention of TSS and nutrients. Farming alone explained 58% of the variation in TSS retention and cattle grazing explained 25% of the variation in TON retention. Therefore, watershed management interventions considering the mitigation of anthropogenic activities could be considered to reduce sediment and nutrient input and release

Environmental and biotic factors affecting freshwater snail intermediate hosts in the Ethiopian Rift Valley region

Background: Knowledge of the distribution and habitat preference of freshwater snail intermediate hosts can provide information to initiate and set-up effective snail control programmes. However, there is limited research conducted on the factors driving the occurrence and abundance of freshwater snail intermediate hosts in the Ethiopian Rift Valley. Hence, in this study, we investigated how environmental and biotic factors influence the occurrence and abundance of the snail intermediate hosts in Ethiopian Rift Valley region. Methods: Data on freshwater snails, physico-chemical water quality parameters, physical characteristics of habitat, predators and competitors, and anthropogenic activity variables were collected from 174 sampling sites during the wet season of 2017 and 2018. Generalized linear models were used to identify the main environmental and biotic factors affecting the occurrence and abundance of the snail species. Results: It was found that Bulinus globosus (31.7%) was the most abundant snail species followed by Lymnaea natalensis (21.6%), Lymnaea truncatula (15.1%) and Biomphalaria pfeifferi (14.6%). Generalized linear models indicated that physico-chemical parameters (water temperature, turbidity, chlorophyll-a, dissolved oxygen, chemical oxygen demand, alkalinity, calcium, magnesium, nitrate and ammonia), physical habitat characteristics (water depth, canopy cover, macrophyte cover and substrate type) and biotic factors (abundance of predators and competitors) were found to be the main variables determining the occurrence and abundance of snail species in the Ethiopian Rift Valley region. In terms of anthropogenic activities, human settlement, farming, bathing and swimming, clothes washing, grazing, drainage of land, car washing, boating, fishing and silviculture were also important variables determining the occurrence and abundance of snail species in the region. Conclusions: The findings reported herein suggest that integrated snail control strategies should be considered to control snails via protection of water bodies from disturbance by anthropogenic activities. In this way, it is possible to reduce the concentration of organic matter and dissolved ions in aquatic ecosystems which are conducive for the presence of snails

Bio-control of anopheles mosquito larvae using invertebrate predators to support human health programs in Ethiopia

Mosquitoes have been a nuisance and health threat to humans for centuries due to their ability to transmit different infectious diseases. Biological control methods have emerged as an alternative or complementary approach to contain vector populations in light of the current spread of insecticide resistance in mosquitoes. Thus, this study aimed to evaluate the predation efficacy of selected potential predators against Anopheles mosquito larvae. Potential invertebrate predators and Anopheles larvae were collected from natural habitats, mainly (temporary) wetlands and ponds in southwest Ethiopia and experiments were conducted under laboratory conditions. Optimal predation conditions with respect to larval instar, water volume and number of predators were determined for each of the seven studied predators. Data analyses were carried out using the Poisson regression model using one way ANOVA at the 5% significant level. The backswimmer (Notonectidae) was the most aggressive predator on Anopheles mosquito larvae with a daily mean predation of 71.5 larvae (95% CI: [65.04;78.59]). Our study shows that larval instar, water volume and number of predators have a significant effect on each predator, except for dragonflies (Libellulidae), with regard to the preference of the larval instar. A selection of mosquito predators has the potential to control Anopheles mosquito larvae, suggesting that they can be used as complementary approach in an integrated malaria vector control strategy

Measuring progress and projecting attainment on the basis of past trends of the health-related Sustainable Development Goals in 188 countries: an analysis from the Global Burden of Disease Study 2016

The UN’s Sustainable Development Goals (SDGs) are grounded in the global ambition of “leaving no one behind”. Understanding today’s gains and gaps for the health-related SDGs is essential for decision makers as they aim to improve the health of populations. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016), we measured 37 of the 50 health-related SDG indicators over the period 1990–2016 for 188 countries, and then on the basis of these past trends, we projected indicators to 2030