Integrated multitrophic aquaculture (IMTA) as an environmentally friendly system for sustainable aquaculture: functionality,species, and application of biofloc technology (BFT)

Environmental Science and Pollution Research - Aquaculture is one of the fastest-growing industries in the world, and its prominent role has been proven in supplying food for the growing world...     

A comparison of standard k–ε and realizable k–ε turbulence models in curved and confluent channels

Environmental Fluid Mechanics - Bends and confluences are often observed in rivers, and one of the phenomena that characterize flows in open channel bends and confluences is secondary current....     

Rheological Investigation of Wood-Polypropylene Composites in Rotational Plate Rheometer

In this research work, the rheological properties of Wood-Plastic Composites (WPC) with some selected compositions are investigated. WPC is being recognized as a green composite that, in the past 20?years, has emerged to a commercial product. A study on rheological properties of these materials can give insight into the proper selection of composition and processing condition. Two grades of polypropylene (PP) with two different melt flow indexes (MFI) were selected to prepare WPCs with three different wood contents (50, 60 and 70?% wt.). Four types of rheological experiments were performed utilizing a rotational plate rheometer: (1) strain sweep, (2) frequency sweep, (3) temperature sweep and (4) steady shear rate sweep. The independent variables were chosen as wood content, MFI of polymer (two types), melt temperature, frequency or shear rate, the gap between the plates, and strain percentage. The strain sweep tests specified the linear and non-linear viscoelastic zones of each experiment. The results of frequency sweep experiments indicated that increasing the wood content and frequency and also decreasing the strain percentage and the gap distance, lead to an increase in the storage modulus. Regarding the loss modulus, wood percentage and the gap distance presented positive effects and strain percentage showed a negative effect. The behavior of complex viscosity was almost similar to that of the storage modulus but increasing the frequency caused a decrease in the complex viscosity. In case of temperature sweep experiments, it was observed that the rheological properties exhibit a rapid change near to a temperature of 160?°C. The results also showed that beyond this point, increasing the wood content and also MFI of polypropylene caused an increase in the storage modulus. The results of steady shear rate sweep experiments specified that increasing wood content and also decreasing the MFI of PP, the gap distance and shear rate lead to an increase in both viscosity and shear stress.     

A study on chemical properties of groundwater and soil in ophiolitic rocks in Firuzabad, east of Shahrood, Iran: with emphasis to heavy metal contamination

In order to assess the chemical properties of groundwater and soil in ophiolitic zone of Firuzabad, in east of Shahrood, Iran, 10 soil samples with regard to sensitive points (vicinity to mine, ophiolitic rocks, and villages) and 10 groundwater samples including nine samples from springs, and also one sample from a well in a village of the study area were taken. These samples were analyzed in laboratories using inductively coupled plasma method. The soil samples were also evaluated for grain size. The obtained results show that most of heavy and major elements were exceeding the permissible levels in soil and water samples in the study area. On the subject of soil quality, concentrations of elements Cr, Mn, Fe, Ca, Mg, Ca, Ni, and Zn are above permissible levels. Enrichment factor and index of geoaccumulation have been calculated for heavy and major elements of all soil samples. According to the obtained results, it may be argued that soil samples are contaminated in relation to the above-mentioned indices. Comparing the concentrations of elements with results of grain size analysis illustrates that the concentrations of Cr, Ni, Fe, Mg, and Co are positively correlated with sand fraction and the concentrations of Al, P, Mn, and Pb are directly proportional with clay fraction in soil samples. The study on water contamination suggests that concentrations of elements Cr, Ni, and Mg in groundwater samples of the study area are above the permissible levels. Some indices like metal index and heavy metal pollution index show that most of the water samples include heavy metal contamination.     

DRASTIC framework improvement using Stepwise Weight Assessment Ratio Analysis (SWARA) and combination of Genetic Algorithm and Entropy

Environmental Science and Pollution Research - Hybrid and integrated techniques can be used to investigate intrinsic uncertainties of the overlay and index groundwater vulnerability assessment...     

Application of Artificial Neural Networks to Predict Total Dissolved Solids at the Karaj Dam

We applied multilayer perceptron (MLP) and radial basis function (RBF) neural networks using data from two water quality monitoring stations at the Karaj Dam in Iran. Input data were calcium ions (Ca²⁺), magnesium ions (Mg²⁺), sodium ions (Na⁺), chloride ions (Cl^?), sulfate (), and pH, and the output data were total dissolved solids (TDS). An MLP with one hidden layer containing eight neurons was selected for the upstream water quality station using normalized input data. We developed a second MLP neural network for the downstream station with one hidden layer containing 10 neurons in the hidden layer using normalized input data. Considering applying normalized input data and one hidden layer, the coefficient of determination (R ²) and index of agreement (IA) between the observed and the predicted data for the upstream and downstream monitoring stations using the MLP neural networks were 0.985, 0.84, 0.99, and 0.92, respectively. The RBF neural network with 100 neurons in its hidden layer reached the minimum errors between the observed and the predicted results in upstream and downstream stations. The R ² between observed and predicted data for upstream and downstream monitoring stations for the RBF was 0.999 and 0.998, respectively. Data normalization improved the performance of the MLP neural networks. Sensitivity analysis indicated that magnesium is the most effective water quality parameter for predicting TDS, and sulfate is the second most effective water quality parameter affecting TDS prediction at the Karaj Dam.     

Performance of activated carbon coated graphite bipolar electrodes on capacitive deionization method for salinity reduction

• Graphite bipolar electrodes act as an appropriate bed for the CDI process. • Activated carbon Coating improves the application of the electrodes. • CDI is an environmentally friendly method to apply for brackish water. • Initial concentration is the most important parameter in the CDI method. • CDI process in a batch-mode setup needs more development. This research investigates a capacitive deionization method for salinity reduction in a batch reactor as a new approach for desalination. Reductions of cost and energy compared with conventional desalination methods are the significant advantages of this approach. In this research, experiments were performed with a pair of graphite bipolar electrodes that were coated with a one-gram activated carbon solution. After completing preliminary tests, the impacts of four parameters on electrical conductivity reduction, including (1) the initial concentration of feed solution, (2) the duration of the tests, (3) the applied voltage, and (4) the pH of the solution, were examined. The results show that the maximum efficiency of electrical conductivity reduction in this laboratory-scale reactor is about 55%. Furthermore, the effects of the initial concentration of feed solution are more significant than the other parameters. Thus, using the capacitive deionization method for water desalination with low and moderate salt concentrations (i.e., brackish water) is proposed as an affordable method. Compared with conventional desalination methods, capacitive deionization is not only more efficient but also potentially more environmentally friendly.     

Field application of SPME as a novel tool for occupational exposure assessment with inhalational anesthetics

Occupational exposure to inhalational anesthetics occurs routinely in operating rooms. It could induce serious health hazards and diseases. This exposure assessment is a crucial step in determining risks. In this study, a pen-shaped holder for solid-phase microextraction (SPME) sampler was successfully applied as a time-weighted average sampling tool for workshift exposure assessment of operation room staff to halothane. It proved to be very convenient for use in occupational environments such as operation rooms. Samples were analyzed by a gas chromatography-mass spectrometry. The validity of the SPME method was checked in real-world conditions with Occupational Safety and Health Administration (OSHA) 103 standard method for the determination of inhalational anesthetics. A good agreement between OSHA 103 and SPME methods was obtained and results demonstrated no statistically significant differences in anesthetic concentrations determined by the two analytical methods (p?≥?0.05). It is concluded that SPME in retracted mode could successfully be applied in occupational exposure assessment purposes.     

Long-term variations of water quality parameters in the Maroon River, Iran

Sixteen water quality parameters have been monitored at four stations located along the Maroon River during 1989?C2008. The trend analysis was performed on seasonal and annual time-scales using the Mann?CKendall test, the Sen??s slope estimator and the linear regression. The relationships of the water quality parameters to river discharge were also investigated. The statistical methods showed both positive and negative trends in annual water quality data. However, significant trends were detected by the statistical methods only in calcium, magnesium, sodium absorption ratio, pH, and turbidity series. The results indicated that the concentrations of the water quality parameters increased in spring and winter seasons, while the concentrations were diluted in summer and autumn seasons in the last two decades. Moreover, the highest numbers of significant trends were found in the spring and summer series, respectively. According to the regression analysis, most of the water quality parameters were negatively correlated with river discharge.     

Experimental study of rubber tire aggregates effect on compressive and dynamic load-bearing properties of cylindrical concrete specimens

Sustainable development has become a major focus for engineers and planners as part of their collective efforts in finding, developing and integrating environmental-friendly solutions for material recycling and waste management into design and construction of civil engineering infrastructure. In the past three decades, there has been an increase in recycling and application of waste materials into the concrete to decrease costs and improve material properties of the concrete. Significant growth in automobile manufacturing industry and increased rubber tire supply for vehicles suggested the application of waste tire particles as concrete aggregates to minimize the ecological footprint of the rubber tire waste due to its recycling process difficulties. In this paper, the effect of rubber tire particles on compressive and dynamic strength of concrete specimens with different particle percentiles was tested on more than 55 cylindrical specimens. To achieve the optimal mix design properties of rubber tire concrete specimens, both fine and coarse aggregates got replaced by fine and coarse rubber particles. Introduction of rubber tire particles as coarse and fine aggregate reduces the brittleness of the concrete and provides more flexible aggregate bonding which ultimately improves the dynamic resistance of the concrete. It increases the concrete workability and provides environmental-friendly and cost-effective solutions in using recycled materials for concrete construction applications.