The Impact of Environmental Variables on Faecal Indicator Bacteria in the Betna River Basin, Bangladesh

Environmental variables influence Faecal Indicator Bacteria (FIB) in surface water. Understanding that influence is important, because presence of FIB, which are an indication of faecal contamination, means that harmful pathogens could be present that could also be influenced by environmental variables. Although some recent studies have focused on this topic, most of this work has been conducted in developed countries. Similar studies in developing countries and in a (sub)tropical climate are lacking. In this study we assess the influence of environmental variables on fluctuations in FIB concentrations of the Betna River in southwest Bangladesh that floods almost every year. Monthly water samples from five locations along Betna River were tested for FIB (E. coli and enterococci) in 2014–2015. A linear regression model was developed to assess the effect of the environmental variables on FIB concentrations. The study revealed increased FIB concentrations during wet weather conditions. Precipitation and water temperature were positively correlated with FIB concentrations. Water temperature was positively correlated, because the warm May to September period coincides with frequent precipitation. Precipitation increases manure release from land to surface water. The regression model explains nearly half of the variability in FIB concentrations (R2 of 0.46 for E. coli and 0.48 for enterococci). This study indicates that increased precipitation combined with higher water temperature, as is expected in this region with climate change, likely increases FIB concentrations. Waterborne pathogens are expected to respond similarly to these environmental changes, indicating that disease outbreaks could well become more frequent and severe.</p

Effect of cover design on moisture removal rate of a cabinet type solar dryer for food drying application

The development and investigation of efficient solar drier, particularly meant for drying vegetables and fruit is described in this paper. Considering the importance of solar drying three different types of natural convection cabinet solar dryers are constructed and their performance are evaluated at natural conditions. To do so moisture removal rate, moisture ratio of various foods (Apple, Banana, pineapple, Guava) are evaluated from 10AM to 4PM for many days in different season. After analysing the moisture removal rate of three different chambers it is appeared that total moisture removal of thin tube chimney type chamber is 44.5%, for attic space type chamber moisture removal is 33.3% and for natural draft chamber it is 58.9% in 6 hours. So, it is clear from this analysis that the performance of natural draft chamber is best than other two chambers and performance of attic space type chamber is worst. This is due to the reflection loss in inclined glass of attic space type dryer compared to other chambers. Besides, the performance of chimney chamber is better than attic space type chamber. It is also seen that moisture removal rate after 1pm is higher than before 1pm as solar irradiation was higher after 1 pm in best performance days. Besides, moisture removal rate of Pineapple is the highest as water level and porosity is so much high and for guava is the lowest as water level and porosity is low. Moisture removal rate of banana is higher than guava but lower than apple.</p

Biogas from mesophilic anaerobic digestion of cow dung using gelatin as additive

A research work was conducted to investigate the enhanced production ability of biogas from mesophilic anaerobic digestions of cow dung (CD) using gelatin as additive. Five laboratory scale digesters were constructed to digest cow dung, where one set up was used for digestion of cow dung without additive and the other set up were used for digestion with additive. Gelatin additive was added in the slurry of amount 0.29, 0,57, 0.85 and 1.14% (wt.). The digesters were made of glass conical flask of 1-liter capacity each. Cow dung was used 335 gm and water was used 365 gm in each experiment. In the slurry, total solid content was maintained 8% (wt.) for all the observations. The digesters were fed on batch basis. The digesters were operated at ambient temperatures of 26 - 35°C. The total gas yield was obtained about 14.4 L/kg CD for digestion without additive and about 65% more biogas for digestion with 0.29% gelatin additive. The retention time for digestion without additive was 38 days and with additive retention time varied between 24 and 52 days.</p

Performance Investigation of High Temperature Application of Molten Solar Salt Nanofluid in a Direct Absorption Solar Collector

Nanofluids have great potential in a wide range of fields including solar thermal applications, where molten salt nanofluids have shown great potential as a heat transfer fluid (HTF) for use in high temperature solar applications. However, no study has investigated the use of molten salt nanofluids as the HTF in direct absorption solar collector systems (DAC). In this study, a two dimensional CFD model of a direct absorption high temperature molten salt nanofluid concentrating solar receiver has been developed to investigate the effects design and operating variables on receiver performance. It has been found that the Carnot efficiency increases with increasing receiver length, solar concentration, increasing height and decreasing inlet velocity. When coupled to a power generation cycle, it is predicted that total system efficiency can exceed 40% when solar concentrations are greater than 100&times;. To impart more emphasis on the temperature rise of the receiver, an adjusted Carnot efficiency has been used in conjunction with the upper temperature limit of the nanofluid. The adjusted total efficiency also resulted in a peak efficiency for solar concentration, which decreased with decreasing volume fraction, implying that each receiver configuration has an optimal solar concentration

Manufacturing of a parabolic trough concentrating collector test rig and a 'LASER-Screen' technique for measuring actual focal length and light interceptance of the collector

A portable parabolic trough-concentrating solar collector test rig was designed, and fabricated using locally available materials and technique. A trough made of any materials and the energy collection element of any geometry with maximum aperture area of 80×100cm2 and 2.5×100cm2 respectively can be fitted readily in the support structure of the rig. A two-axis manual tracking system allows the rig to track the sun daily from east to west for every 5° interval, and seasonally from 50°North to 80°South for every 15°. In addition to this, actual focal length and light interceptance were investigated applying customised “LASER-Screen” technique. An average light interceptance of the rig for a 2.5 cm diameter absorber tube was measured to be 85.9%. The focal length of the 100 cm long test rig was found to be 18.167±1.35cm. The test rig will facilitate to investigate the energy potential in Chittagong region of Bangladesh

Sustainable food drying technologies based on renewable energy sources

Waste in the food supply chain is estimated to be about 30–40% of the total food production, which aggravates the world hunger and increases waste management burden and environmental impact. Despite the dire food scarcity, majority of this food waste takes place in developing countries because of the lack of appropriate and affordable preservation techniques. Traditional open sun drying is the most popular food-reservation technique to the local farmers due to near-zero capital cost and cheap labor cost. However, this method is highly energy intensive, unhygienic, and time demanding. The high energy consumption resulting from uncontrolled simultaneous heat, mass, and momentum transfer processes in traditional drying systems highlights the necessity of pursuing sustainability in drying process targeting reduced energy consumption, environmental and social impacts. This paper presents a comprehensive review on the sustainable food drying technologies based on renewable energy sources, with emphasis on the developing countries. It was observed that the integration of thermal energy storage with heat pump makes the integrated drying system more efficient, and dries food with better quality. Likewise, advanced integrated drying systems, such as, solar with microwave, and heat pump with microwave make the drying process more cost and quality competent. Finally, impact of resource distribution and governmental incentives for renewable energy use in sustainable drying is discussed

Higher gravidity and parity are associated with increased prevalence of metabolic syndrome among rural Bangladeshi women.

BACKGROUND: Parity increases the risk for coronary heart disease; however, its association with metabolic syndrome among women in low-income countries is still unknown. OBJECTIVE: This study investigates the association between parity or gravidity and metabolic syndrome in rural Bangladeshi women. METHODS: A cross-sectional study was conducted in 1,219 women aged 15-75 years from rural Bangladesh. Metabolic syndrome was defined according to the standard NCEP-ATP III criteria. Logistic regression was used to estimate the association between parity and gravidity and metabolic syndrome, with adjustment of potential confounding variables. RESULTS: Subjects with the highest gravidity (> = 4) had 1.66 times higher odds of having metabolic syndrome compared to those in the lowest gravidity (0-1) (P trend = 0.02). A similar association was found between parity and metabolic syndrome (P(trend) = 0.04), i.e., subjects in the highest parity (> = 4) had 1.65 times higher odds of having metabolic syndrome compared to those in the lowest parity (0-1). This positive association of parity and gravidity with metabolic syndrome was confined to pre-menopausal women (P(trend) <0.01). Among the components of metabolic syndrome only high blood pressure showed positive association with parity and gravidity (P(trend) = 0.01 and <0.001). Neither Parity nor gravidity was appreciably associated with other components of metabolic syndrome. CONCLUSIONS: Multi parity or gravidity may be a risk factor for metabolic syndrome

Higher Gravidity and Parity Are Associated with Increased Prevalence of Metabolic Syndrome among Rural Bangladeshi Women

10.1371/journal.pone.0068319PLoS ONE88e6831