Numerical Simulation Investigation of a Double Skin Transpired Solar Air Collector

Transpired solar collectors (TSC) are one of the most popular solar thermal technologies for building façades. TSC use solar energy to heat the absorber surface, which transmits thermal energy to the ambient air. A variant of TSC, namely, a double skin transpired solar collector (DSTSC), has been analyzed in this paper, thus providing guide values and a technical point of view for engineers, architects, and constructors when designing such transpired solar collectors. Three important parameters were addressed in this study through numerical simulation: the influence of a separation plate introduced in a TSC, turning it into a DSTSC; the air layer thickness influence on the performance of the collector; and the influence of the used absorber materials for the separation plate material. Greater heat exchange efficiency was noticed for the DSTSC at every imposed airflow rate compared with the TSC. Regarding the thickness of the collector, the efficiency gradually increased when increasing the solar collector thickness until it reached a value of 20 cm, though not varying significantly at a thickness of 30 cm.

Heavy Metal and Trace Element Bioaccumulation in Muscle and Liver of the Merlu (Merluccius merluccius Linneaus, 1758) from the Gulf of Bejaia in Algeria

This preliminary study aims at assessing a contamination level of Bejaia Gulf by some Metallic Trace Elements (MTEs) such as zinc, iron, copper, nickel, lead and cadmium. The use of hake, Merluccius merluccius (Linneaus, 1758) as a bio-indicator of these heavy metals, made it possible to put in an obvious the presence of these micropollutants at the level of two target organs, the liver, detoxifying organ and the muscle, the most prized part by consumer. The MTE assays are performed using a Flame Atomic Absorption Spectrophotometer (FAAS). As for the fish contamination level, it is referred to the guide values of the WHO, FAO and Algerian recommendations. Within the framework of our study, the recorded values show that hake accumulates all metal pollutants being analyzed. Iron and zinc exhibit the highest concentration, the presence of nickel and copper were also recorded. Lead and cadmium have critical concentrations exceeding even Algerian standards. These results revealed no significant difference in both sexes and in both target organs. However, the study indicates considerable contamination in young fish with significant concentrations according to established standards. These data reveal that Merluccius merluccius is a bio-indicator of marine pollution in the Gulf of Bejaia.

Persistent Organic Pollutants and Metals in Atmospheric Deposition Rates around the Port-Industrial Area of Civitavecchia, Italy

In recent years, studies on climate change have focused on reducing greenhouse gas emissions emitted by various civil and industrial processes. This study highlights the importance of characterizing the total deposition rates of airborne particles (bulk atmospheric deposition) in the surroundings of an industrial area along the north cost of the Lazio Region in Italy, to deepen knowledge about the potential impact of emissions from the coal-fired thermoelectric (CTE) power plant and other possible sources existing in the surrounding area. Four sampling sites were identified, and the monitoring plan was performed a yearlong with monthly collecting observation. The deposition samples were collected monthly and processed for determining organic (polychlorinated dibenzo-para-dioxins, PCDDs; polychlorinated dibenzofurans, PCDFs; dioxin-like polychlorinated biphenyls, DL-PCBs; polycyclic aromatic hydrocarbons, PAHs) and inorganic (metals) substances. The samples were collected monthly and sent for chemical characterization. In Europe and Italy, no reference values have been given for the deposition rates of chemicals, while some European countries have determined reference/guide values to which the authors will refer in this study. Therefore, the analytical results show that the deposition rates for PCDD/Fs and DL-PCBs are lower with respects guide values defined by Germany and Belgium; PAHs values are in line with those measured in other rural-type sites, while for metals the analytical results show a situation between rural and urban area. The approach used in this study can help to identify reference values for Italy in deposition rates, with the aim both to characterize the dynamic of pollution in area with multiple risk factors and to describe and protect human health from environmental exposures caused by the contamination of the food chain.

Impacts of Agrochemicals on Water Quality Parameters in Aboisso Region (South-East of Cote d’Ivoire)

Aboisso region is experiencing unprecedented agricultural activities. Cultural techniques such as the use of insecticides are harming the quality of water. This study aims to assess the impact of insecticides on the water quality in the Aboisso region. Thirty-one (31) water points (10 surface water and 21 groundwater) were sampled. The determination of physicochemical parameters as well as the multi-residue method used for insecticides analysis in the samples allowed us to achieve our objective. The result of the physicochemical analysis shows that the temperature of groundwater (27.91°C) is higher than surface water temperature (26.77°C). These waters are mostly acidic with a slightly lower pH for groundwater (6.46) compared to surface water (6.54). The conductivity is higher in groundwater (average of 130.46 µS/cm) as opposed to surface water (average of 43.50 µS/cm). After applying the multi-residue method, the results reveal the presence of nine (9) active ingredients. In surface waters, all these molecules, except Lambda-cyhalothrin and Deltamethrin, exceed the WHO guide values (0.1 µg/L). The highest concentrations recorded concern ethyl parathion and profenofos (8.24 µg/L and 8.04 µg/L respectively). In groundwater, it is rather Parathion-methyl, Profenofos, Dimethoate, Chlorpyriphos-ethyl, Lambda-cyhalothrin and Deltamethrin that are often at below WHO standards. However, the present study reveals that all of the water samples analysed were polluted, owing to anthropogenic used of insecticides in the region, and other chemicals with high concentrations of parathion-ethyl: 8.24 µg/L and profenofos: 8.04 µg/L. These waters are therefore unfit for human consumption.

Air born bacteria evaluation in the kitchen air of restaurants in Babol City

Background and purpose: Bioaerosols enter into human body through various ways (inhalation, ingestion or skin absorption). The aim of this study was to investigate the type and density of the predominant bacteria in two seasons - cold and warm - in the kitchen air of restaurants. Materials and Methods: This descriptive cross-sectional study was conducted on the air of restaurants' kitchen in Babol. Sampling was performed by using a personal sampling pump with impinger tank using a flow rate of 4 l/min during 50 minutes. Counting the colonies in the air was determined in terms of CFU/m3 and the type of grown bacteria was identified using different tests, such as Gram staining and biochemical methods. Temperature and humidity were recorded at the time of sampling, too. Totally, 120 samples of bacteria were taken from the indoor air of kitchens with and without air conditioning. Results: The results showed that the highest and lowest densities of bacteria in cold season were 15 CFU/m3 and 63.7 CFU/m3, and in warm season, they were 19.6 CFU/m3 and 80 CFU/m3, respectively. The predominant bacteria were Gram-positive bacteria in the air of kitchen but Bacillus and Micrococcus were the most frequent. Conclusion: The results showed that due to humidity and the temperature (warmer), bacterial density was higher in summer than winter. The concentration of bacteria in the kitchen and restaurant was also less than WHO recommendation and guide values ACGIH (up to 500 CFU/m3), respectively. So, air quality was found to be good and acceptable in terms of the restaurant kitchen.

Filter Cassette Method for Analyzing Man-Made Vitreous Fibers Settled on Surfaces

A new method was developed to analyze the surface count of fibers in a variety of environments. The method entails sampling surfaces with the help of suction to a filter cassette holder containing a cellulose filter. The filters were collapsed using microwave digestion in dilute acid, and the fibers filtered to polycarbonate filters, gilded, and analyzed by scanning electron microscopy (SEM). The method was compared to traditional gel tape sampling as described in International Standards Organization (ISO) standard 16000-27, following analysis with phase contrast microscopy. The methods were compared in industrial environments and in office-type environments, with the concentration range studied spanning from 0.1 to 100,000 fibers/cm2. The methods yielded similar results (p < 0.05) in concentrations from 100 to 10,000 cfu/cm2, while the filter cassette method gave systematically higher results in high concentrations (>10,000 cfu/cm2) as well as in all office-type environments studied, where the fiber count ranged from 0.1 to 20 fibers/cm2. Consequently, we recommend using the new method in working environments where the surface count is more than 100 fibers/cm2, as well as in office-type environments where the fiber count is below 10 fibers/cm2. It should be noted, however, that a similar limit of quantitation as with the gel tape method (0.1 fibers/cm2) requires sampling a minimum area of 100 × 100 cm2 with the fiber cassette method. Using the filter cassette method will require new guide values to be formed for office-type environments, since the results are higher than with the gel tape method. Alternatively, if present guide values or limit values are to be used with the filter cassette method, conventions as to which fiber sizes to count should be set, since SEM analysis in any case will allow for including a larger size range than phase contrast microscopy (PM). We, however, recommend against such an approach, since fibers less than 1 µm in width may not be less harmful by inhalation than larger fibers.