Forced-convective cooling of citrus fruit: Package design

Optimisation of package design for citrus fruit is required to increase the throughput, by reducing the precooling time, and to enhance fruit quality by providing fast and uniform cooling without inducing chilling injury. The cooling performance of an existing container and of two new containers (Supervent and Ecopack), as stacked on a pallet, was evaluated experimentally and numerically with computational fluid dynamics (CFD). The accuracy of the CFD simulations was confirmed by a good agreement with experiments. The best cooling performance was found for Ecopack, but removing airflow short circuits in this container may enhance the cooling performance even more. Also with respect to uniformity of cooling of the fruit and the magnitude of the convective heat transfer coefficients, in a specific container and between different containers on the pallet, the Ecopack container performed best, followed by the Supervent and the standard container. The new container designs thus clearly showed significant improvements in cooling performance.     

Speciation of selected trace elements in three Ethiopian Rift Valley Lakes (Koka, Ziway, and Awassa) and their major inflows

The Ethiopian Rift Valley Lakes (ERVLs) are water resources which have considerable environmental, economic and cultural importance. However, there is an increasing concern that increasing human activities around these lakes and their main inflows can result in increased contamination of these water bodies. Information on total concentrations of some trace elements is available for these lakes and their inflows; however, data on the trace element speciation is lacking. Therefore, the objective of this study was to determine the low molecular mass (LMM) trace element species and also, evaluate the influence of flooding episodes on the LMM trace element fractions. At-site size and charge fractionation system was used for sampling of water from the lakes Koka, Ziway and Awassa and their main inflows during the dry and wet seasons. The results showed that chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb) in Lake Koka and its inflows as well as in Lake Ziway were predominantly present as HMM (high molecular mass, i.e., > 10 kDa) forms, while arsenic (As), selenium (Se), cadmium (Cd) were more mobile during the dry season. In Lake Awassa, all except Cr and Mn were predominantly found as LMM species (low molecular mass, i.e. < 10 kDa) which can be attributed to the high concentrations of LMM DOC (dissolved organic carbon). During the wet season, results from the Lake Koka and its inflows showed that all trace elements were predominantly associated with HMM forms such as colloids and particles, demonstrating that the mobility of elements was reduced during the wet season. The colloidal fraction of elements such as Cr, Ni, and Cd was also correlated with dissolved Fe. As the concentration of LMM trace element species are very low, the mobility, biological uptake and the potential environmental impact should be low.     

Ventilation system to minimize airborne bacteria, dust, humidity, and ammonia in calf nurseries.

We installed a ventilation system that minimizes airborne bacteria, dust, humidity, and ammonia levels; conserves animal heat during the winter months by precise control of the amount of fresh air admitted to the calf nursery; and prevents cross transfer of airborne pathogens between neighboring calves by providing uniform air distribution throughout the calf nursery. Because of the effectiveness of air filtration and uniform air distribution within the nurseries, respiratory problems of calves were reduced greatly. Airborne dust and bacteria as small as .5 mu were filtered from the air.     

Use of Sequencing Batch Reactor for Biological Denitrification of High Nitrate-Containing Water

The efficiency of a sequencing batch reactor in denitrification of drinking water with relatively high nitrate concentrations (40–250 mg∕L as N) was evaluated. Ethanol at a COD∕N of 2.00 was found sufficient to reduce nitrate concentrations to acceptable levels (<10 mg∕L as N). Within the first 6 min of reaction, nitrite accumulation in the range of 0.03–3.5 mg∕L as N was observed increasing with the increase of initial nitrate concentrations. In the first hour, nitrate removal was significantly high in the range of 85.7–91.5%. Anoxic reaction times of 3, 5, and 7 h were required for nitrate concentrations of 40–160, 200, and 250 mg∕L (as N) to achieve acceptable levels of nitrate and nitrite. Alkalinity of the denitrified water increased on average by 3.53 mg as CaCO3 for each milligram of nitrate reduced and pH increased from 7.3 to the range of 8 to 9. Idle times between the operation cycles, in the range of 1–14 h, had an insignificant effect on denitrification. Residual COD concentrations in the range of 5–15 mg∕L and sulfide concentrations (at initial nitrate concentrations ≥120 mg∕L as N) in the range of 0.2–0.4 mg∕L were recorded in the finished water. Elevated concentrations of COD in general are not advisable in drinking water, and specifically in this case, it could result in toxic sulfide formation in the treated water. There is a need to further study the optimization of the use of ethanol and polishing of the treated water. A sequencing batch reactor has the potential of being used as an alternative configuration for biological denitrification of drinking water.     

Removal of Pb(II) from aqueous media using adsorption onto polyaniline coated sisal fibers

Lead is one of the toxic metals that cause detrimental health disorders. Polyaniline (PAni) coated sisal fibers were prepared via in situ polymerization and used to remove Pb(II) from wastewater. PAni/SF was investigated on batch experiment to remove Pb(II) from wastewater as a function of contact time, pH, particle size, adsorbent, and adsorbate dose. Studies on kinetics revealed adsorption of Pb(II) obeyed pseudo second order. Adsorption equilibrium was suitably fitted in Langmuir isotherm with linear coefficient 0.99. Finally, PAni/SF composites show appreciable removal efficiency with a maximum adsorption capacity of 6.53 mg/g, consistent with adsorption capacity obtained from pseudo second order. J. VINYL ADDIT. TECHNOL., 25:189–197, 2019. © 2018 Society of Plastics Engineers     

Aspergillus and aflatoxin in groundnut (Arachis hypogaea L.) and groundnut cake in Eastern Ethiopia

This study was conducted to assess major Aspergillus species and aflatoxins associated with groundnut seeds and cake in Eastern Ethiopia and evaluate growers’ management practices. A total of 160 groundnut seed samples from farmers’ stores and 50 groundnut cake samples from cafe and restaurants were collected. Fungal isolation was done from groundnut seed samples. Aspergillus flavus was the dominant species followed by Aspergillus parasiticus. Aflatoxin analyses of groundnut seed samples were performed using ultra performance liquid chromatography; 22.5% and 41.3% of samples were positive, with total aflatoxin concentrations of 786 and 3135 ng g^?1 from 2013/2014 and 2014/2015 samples, respectively. The level of specific aflatoxin concentration varied between 0.1 and 2526 ng g^?1 for B₂ and B₁, respectively. Among contaminated samples of groundnut cake, 68% exhibited aflatoxin concentration below 20 ng g^?1, while as high as 158 ng g^?1 aflatoxin B₁ was recorded. The study confirms high contamination of groundnut products in East Ethiopia.     

Aflatoxin B1 and total fumonisin contamination and their producing fungi in fresh and stored sorghum grain in East Hararghe,Ethiopia

Natural contamination of sorghum grains by aflatoxin B₁ and total fumonisin and their producing toxigenic fungi has been studied. A total of 90 sorghum grain samples were collected from small-scale farmers’ threshing floors and 5–6 months later from underground pits during 2013 harvest from three districts of East Hararghe, Ethiopia. Mycotoxin analysis was done using enzyme-linked immunosorbent assay (ELISA). The limits of detection were in the range 0.01–0.03 μg kg^–1. The results revealed that all sorghum grain samples were contaminated with both Aspergillus and Fusarium species. Aflatoxin B₁ was detected at levels ranging from ?1 grain. There were marked variations in aflatoxin B₁ concentrations between fresh and stored samples, with much higher levels in the latter. Total fumonisin levels varied between 907 and 2041 µg kg^?1 grain across the samples. Lowest total fumonisin was recorded in freshly harvested sorghum grain samples. Sorghum is a main staple cereal in the studied districts and its consumption per day per person is high. Daily intake of low doses of mycotoxin-contaminated food stuff over a period of time could lead to chronic mycotoxicosis.     

Regional energy system optimization – Potential for a regional heat market

Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO₂ from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO₂ emissions from electricity production is important as the difference of emitted CO₂ between the accounting methods exceeds 650 kton/year for some scenarios.     

Adding clicks to bricks: a case study of e-commerce adoption by a Catalan small retailer

This paper explores why and how one small business adopted e-commerce. Understanding the importance of a chronological perspective, the paper first develops a conceptual model that explicitly incorporates both different stages of e-commerce functionality and the different phases of the e-commerce adoption process. It relates these to a set of adoption factors classified into contextual, organisational, managerial, and e-commerce-specific categories. The paper explores and illustrates the model with the case history of a wine retailing microenterprise based in Catalonia, Spain that ultimately failed. The presented model is found to provide a workable basis for analysis, and the findings demonstrate the way in which different factors affect different phases of the adoption process. More generally, it finds expected contextual factors such as competitors or customers to have little impact on adoption, which is affected more by informal processes and social relations. The paper ends by questioning the simplicity of progressive e-commerce models that fail to incorporate abandonment of the technology, and fail to account for the lack of business value that some e-commerce projects deliver. The case's chronological approach also identifies the path-dependent manner in which earlier decisions impact later e-commerce trajectories, with short-term, subjective decisions potentially constraining e-commerce in the longer term.