Search results for: dissolved oxygen accumulation

Authors: Alla V. Goncharova, Tatyana A. Karpenyuk, Yana S. Tsurkan, Rosa U. Beisembaeva, Togzhan D. Mukasheva, Ludmila V. Ignatova, Ramza Z. Berzhanova

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In this work the effect of culturing conditions of filamentous fungi Penicillium raistrickii, Penicillium anatolicum, Fusarium sp. on biomass yield, the content of total lipids and fatty acids was studied. It has been established that in time the process of lipids accumulation correlated with biomass growth of cultures, reaching maximum values in stationary growth phase. Biomass yield and accumulation of general lipids was increased by adding zinc to the culture medium. The more intensive accumulation of biomass and general lipids was observed at temperature 18°C. Lowering the temperature of culturing has changed the ratio of saturated: Unsaturated fatty acids in the direction of increasing the latter.

Keywords: biomass, culturing conditions, fungi, fatty acids (FA), growth dynamics, lipids

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Authors: Maryam Ehsanpour, Majid Afkhami ‎

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This study investigated the presence of hydrocarbon pollution in industrial waste water sediments found in west coast of Bandar Abass (northern part of Hormoz strait). Therefore, six transects from west of the city were selected. Each transect consists of three stations intervals 100, 600 and 1100 meter from the low tide were sampled in both the summer and winter season (July and January 2009). Physical and chemical parameters of water, concentration of total petroleum hydrocarbons (TPH) and soil tissue deposition were evaluated according to standard procedures of MOOPAM. Average results of dissolved oxygen were 6.42 mg/l, temperature 26.31°C, pH 8.55, EC 54.47 ms/cm and salinity 35.98 g/l respectively. Results indicate that minimum, maximum and average concentration of total petroleum hydrocarbons (TPH) in sediments were, 60.18, 751.83, and 229.21 µg/kg respectively which are less than comparable studies in other parts of Persian Gulf.

Keywords: oil pollution, Bandar Abbas, costal sediments, TPH ‎

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Authors: Anastasiya Vouchak, Aliaksandr Volchak

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Belarus is not short of water. However, there is a problem of water quality. Its pollution has both natural and man-made origin. This research is based on data from State Water Cadastre of the Republic of Belarus registered from 1994 to 2014. We analyzed changes in such hydro-chemical criteria as concentration of ammonium ions, suspended matter, dissolved oxygen, oil-products, nitrites, phosphates in water, dichromate value, water impurity index, 5-day biochemical oxygen demand (BOD). Pollution of water with ammonium ions was observed in Belarus rivers of the Western Dvina, Polota, Schara, Usha, Muhavets, Berzina, Plissa, Svisloch, Pripiat, Yaselda in 2006-2014. The threshold limit value (TLV) was 1.5-3 times as much. Concentration of ammonia in the Berezina exceeded 3 – 5 times the TLVs in 2006-2010. Maximum excess of TLV was registered in the Svisloch (10 km downstream of Minsk) in 2006-2007. It was over 4 mg/dm³ whereas the norm is 0.39 mg/dm³. In 1997 there were ammonia pollution spots in the Dnieper, the Berezina, and the Svisloch Rivers. Since 2006 we have observed pollution spots in the Neman, Ross, Vilia, Sozh, Gorin Rivers, the Osipovichi and Soligorsk reservoirs. Dichromate value exceeds the TLVs in 40% cases. The most polluted waters are the Muhavets, Berezina, Pripiat, Yaselda, Gorin Rivers, the Vileyka and Soligorsk reservoirs. The Western Dvina, Neman, Viliya, Schara, Svisloch, and Plissa Rivers are less polluted. The Dnieper is the cleanest in this respect. In terms of BOD, water is polluted in the Neman, Muhavets, Svisloch, Yaselda, Gorin Rivers, the Osipovichi, Zaslavl, and Soligorsk reservoirs. The Western Dvina, Polota, Sozh, Iputs Rivers and Lake Naroch are not polluted in this respect. This criterion has been decreasing in 33 out of 42 cases. The least suspended matter is in the Berezina, Sozh, Iputs Rivers and Lake Naroch. The muddiest water is in the Neman, Usha, Svisloch, Pripyat, Yaselda Rivers, the Osipovichi and Soligorsk reservoirs. Water impurity index shows reduction of this criterion at all gauge stations. Multi-year average values predominantly (66.6%) correspond to the third class of water quality, i.e. moderately polluted. They include the Western Dvina, Ross, Usha, Muhavets, Dnieper, Berezina, Plissa, Iputs, Pripyat, Yaselda, Gorin Rivers, the Osipovichi and Soligorsk reservoirs. Water in the Svisloch River downstream of Minsk is of the forth quality class, i.e. most polluted. In the rest cases (33.3%) water is relatively clean. They include the Lidea, Schara, Viliya, Sozh Rivers, Lake Lukoml, Lake Naroch, Vileyka and Zaslavl reservoirs. Multi-year average values range from 7.0 to 9.5 mg О₂/dm³. The Yaselda has the least value - 6.7 mg О₂/dm³. A shortage of dissolved oxygen was found in the Berezina (2010), the Yaselda (2007), the Plissa (2011-2014), the Soligorsk reservoir (1996). Contamination of water with oil-products was observed everywhere in 1994-1999. Some spots were found in the Western Dvina, Vilia, Usha, Dnieper in 2003-2006, in the Svisloch in 2002-2012. We are observing gradual decrease of oil pollutants in surface water. The quality of 67 % surface water is referred to as moderately polluted.

Keywords: belarus, hydro-chemical criteria, water pollution, water quality

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Authors: Adesola O. Orimoloye, Mohammed N. Kajama, Edward Gobina

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Gas permeation of Oxygen [O2] and Nitrogen [N2] were investigated at room temperature using 15 and 6000nm pore diameter tubular commercial alumina ceramic membranes with pressure values ranging 1.00 to 2.50 bar. The flow rates of up to 2.59 and 2.77 l/min were achieved for O2 and N2 respectively. The ratio of O2/N2 flow rates were used to compute the O2/N2 selectivity. The experimental O2/N2 selectivity obtained for 15 nm was 1.05 while the 6000 nm indicated 0.95.

Keywords: gas separation, nitrogen, oxygen, selectivity

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Authors: Gurpreet Kaur, Manoj Kumar, Vandana Bhalla

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Strong acceptor-weak acceptor system FN-TPy has been designed and synthesized which undergoes solvent dependent self-assembly in mixed aqueous media to generate through space intermolecular charge transfer assemblies. The as prepared entropically favoured assemblies of FN-TPy exhibit excellent photostability and photosensitizing properties in the assembled state to activate aerial oxygen for efficient generation of reactive oxygen species (ROS) through Type-I and Type-II pathways. The FN-TPy assemblies exhibit excellent potential for regulated oxidation of alcohols and aldehydes under mild reaction conditions (visible light irradiation, aqueous media, room temperature) using aerial oxygen as the ‘oxidant’. The present study demonstrates the potential of FN-TPy assemblies to catalyze controlled oxidation of benzyl alcohol to benzaldehyde and to corresponding benzoic acid.

Keywords: oxidations, photosensitizer, reactive oxygen species, supramolecular assemblies, through space charge transfer.

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Authors: Atef M. Ghaleb, Mohamed Z. Ramadan, Khalid Saad Aljaloud

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The aim of this study is to assesses the lifting capabilities of persons experiencing hypoxia. It also examines the behavior of the physiological response induced through the lifting process related to changing in the hypoxia and lifting frequency variables. For this purpose, the study performed two consecutive tests by using; (1) training and acclimatization; and (2) an actual collection of data. A total of 10 male students from King Saud University, Kingdom of Saudi Arabia, were recruited in the study. A two-way repeated measures design, with two independent variables (ambient oxygen (15%, 18% and 21%)) and lifting frequency (1 lift/min and 4 lifts/min) and four dependent variables i.e., maximum acceptable weight of lift (MAWL), Electromyography (EMG) of four muscle groups (anterior deltoid, trapezius, biceps brachii, and erector spinae), rating of perceived exertion (RPE), and rating of oxygen feeling (ROF) were used in this study. The results show that lifting frequency has significantly impacted the MAWL and muscles’ activities. The oxygen content had a significant effect on the RPE and ROE. The study has revealed that acclimatization and training sessions significantly reduce the effect of the hypoxia on the human physiological parameters during the manual materials handling tasks.

Keywords: lifting capabilities, muscle activities, oxygen content, perceived exertion

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Authors: Nipun Manirajan, Heeralal Gargama, Sushil Guhe, Manoj Prabhakaran

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In railway industry, train sets are designed based on contractual requirements (mission profile), where reliability targets are measured in terms of mean distance between failures (MDBF). However, during the beginning of revenue services, trains do not achieve the designed mission profile distance (mileage) within the timeframe due to infrastructure constraints, scarcity of commuters or other operational challenges thereby not respecting the original design inputs. Since trains do not run sufficiently and do not achieve the designed mileage within the specified time, car builder has a risk of not achieving the contractual MDBF target. This paper proposes a constant failure rate based model to deal with the situations where mileage accumulation is not a part of the design mission profile. The model provides appropriate MDBF target to be demonstrated based on actual accumulated mileage. A case study of rolling stock running in the field is undertaken to analyze the failure data and MDBF target demonstration during low mileage accumulation. The results of case study prove that with the proposed method, reliability targets are achieved under low mileage accumulation.

Keywords: mean distance between failures, mileage-based reliability, reliability target appropriations, rolling stock reliability

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Authors: Boonsiri Dandumrongsin, Halis Simsek, Chaiwat Rongsayamanont

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Dissolved organic nitrogen (DON) is known as one of the persistence nitrogenous pollutant being originated from secondary treated effluent of municipal sewage treatment plant. However, effect of key system operating condition on the fate and behavior of residual DON in the treated effluent is still not known. This study aims to investigate effect of organic loading rate (OLR) on the residual level of DON in the biofilm reactor effluent. Synthetic municipal wastewater was fed into moving bed biofilm reactors at OLR of 1.6x10-3 and 3.2x10-3 kg SCOD/m3-d. The results showed higher organic removal efficiency was found in the reactor operating at higher OLR. However, DON was observed at higher value in the effluent of the higher OLR reactor than that of the lower OLR reactor evidencing a clear influence of OLR on the residual DON level in the treated effluent of the biofilm reactors. It is possible that the lower DON being observed in the reactor at lower OLR is likely to be a result of providing the microbe with the additional period for utilizing the refractory DON molecules during operation at lower organic loading. All the experiments were repeated using raw wastewaters and similar trend was obtained.

Keywords: dissolved organic nitrogen, hydraulic retention time, moving bed biofilm reactor, soluble microbial products

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Authors: Abimbola M. Enitan, Josiah Adeyemo, Sheena Kumari, Feroz M. Swalaha, Faizal Bux

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With the competing demand on water resources and water reuse, discharge of industrial effluents into the aquatic environment has become an important issue. Much attention has been placed on the impact of industrial wastewater on water bodies worldwide due to the accumulation of organic and inorganic matter in the receiving water bodies. The scope of the present work is to assess the physic-chemical composition of the wastewater produced from one of the brewery industry in South Africa. This is to estimate the environmental impact of its discharge into the receiving water bodies or the municipal treatment plant. The parameters monitored for the quantitative analysis of brewery wastewater include biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids, volatile suspended solids, ammonia, total oxidized nitrogen, nitrate, nitrite, phosphorus, and alkalinity content. In average, the COD concentration of the brewery effluent was 5340.97 mg/l with average pH values of 4.0 to 6.7. The BOD and the solids content of the wastewater from the brewery industry were high. This means that the effluent is very rich in organic content and its discharge into the water bodies or the municipal treatment plant could cause environmental pollution or damage the treatment plant. In addition, there were variations in the wastewater composition throughout the monitoring period. This might be as a result of different activities that take place during the production process, as well as the effects of the peak period of beer production on the water usage.

Keywords: Brewery wastewater, environmental pollution, industrial effluents, physic-chemical composition

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Authors: Ahsan Khan, Nazish Shah, Muhammad Salman

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The present study deals with the toxicological effects of copper, lead and chromium on brain and liver tissues of grass carp (Ctenopharyngodon idella). The average length of experimental fish was 8.5 ± 5.5 cm and weighed 9.5 ± 6.5 g. Grass carp was exposed to lethal concentration (LC₁₅) of copper, lead and chromium for 24, 48, 72 and 96 hours respectively. (LC₁₅) for copper was 1.5, 1.4, 1.2 and 1mgL⁻¹. Similarly, LC₁₅ of lead was 250, 235, 225 and 216mgL⁻¹ while (LC₁₅) for chromium was 25.5, 22.5, 20 and 18mgL⁻¹ respectively. During the time of exposure against various doses of heavy metals the grass carp showed some behavioral changes. In the initial stages of experiment, the rapid movements and gulping of air were observed. Several times the fish tried to jump to scat from the toxic median. In addition, the accumulation of heavy metals in different tissues of grass carp particularly in liver and brain tissues were observed. Lead was highly accumulated in brain tissue after the exposure of fish for 24 and 48 hours, while highly accumulated in liver tissues after the exposure of fish for 72 and 96 hours. Chromium was highly accumulated in the liver tissues after the exposure of fish for 24 hours while its accumulation was found highly in the brain tissues after the exposure of fish for 48, 72 and 96 hours. Similarly, accumulation of copper concentration was found highly in brain tissues after the exposure of 48 and 96 hours while its accumulation was high in liver tissues after the exposure of 24 and 72 hours. Comparatively maximum accumulation of lead was found in brain and liver tissues of grass carp followed by chromium and copper. Furthermore, accumulation of these metals caused many abnormalities like gliosis, destruction of cell, change in cell shape and shrinkage of cells in brain tissue while in liver tissues aggregation in hepatocytes, widen space between cells and also destruction of cell was observed. These experiments and observations can be useful to monitor the aquatic pollution and quality of aquatic environment system.

Keywords: brain, grass carp, liver, lethal concentration, toxicity

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Authors: Igor Svishchev, Kashif Choudhry

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Progress in advanced energy technologies is not feasible without understanding how engineering materials perform under extreme environmental conditions. The corrosion behaviour of Fe-Ni-Cr and Zr alloys has been systematically examined under high-temperature and supercritical water flow conditions. The changes in elemental release rate and dissolved gas concentration provide valuable insights into the mechanism of passivation by forming oxide films. A non-intrusive method for monitoring the extent of surface oxidation based on hydrogen release rate has been developed. This approach can be used for the on-line monitoring corrosion behavior of reactor materials without the need to interrupt the flow and remove corrosion coupons. Surface catalysed thermochemical reactions may generate sufficient hydrogen to have an effect on the accumulation of oxidizing species generated by radiolytic processes in the heat transport systems of the supercritical water cooled nuclear reactor.

Keywords: high-temperature corrosion, non-intrusive monitoring, reactor materials, supercritical water

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Authors: Guankai Lin, Wei Tong, Hong Zhu

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The electric current induced Joule heating effects have been investigated in La₀.₈Ba₀.₂MnO₃ ultrathin films deposited on LaAlO₃(001) single crystal substrate with smaller lattice constant by using the sol-gel method. By applying moderate bias currents (~ 10 mA), it is found that Joule self-heating simply gives rise to a temperature deviation between the thermostat and the test sample, but the intrinsic ρ(T) relationship measured at a low current (0.1 mA) changes little. However, it is noteworthy that the low-temperature transport behavior degrades from metallic to insulating state after applying higher bias currents ( > 31 mA) in a vacuum. Furthermore, metallic transport can be recovered by placing the degraded film in air. The results clearly suggest that the oxygen vacancy in the La₀.₈Ba₀.₂MnO₃ films is controllable in different atmospheres, particularly with the aid of the Joule self-heating. According to the SEM images, we attribute the controlled oxygen vacancy to the nano-sized labyrinth pattern of the films, where the large surface-to-volume ratio plays a curial role.

Keywords: controlling oxygen vacancy, joule self-heating, manganite, sol-gel method

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Authors: J. H. Park, R. H. Hwang, K. B. Yi

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Carbon Capture and Storage (CCS) is one of the important technology to reduce the CO₂ emission from large stationary sources such as a power plant. Among the carbon technologies for power plants, chemical looping combustion (CLC) has attracted much attention due to a higher thermal efficiency and a lower cost of electricity. A CLC process is consists of a fuel reactor and an air reactor which are interconnected fluidized bed reactor. In the fuel reactor, an oxygen carrier (OC) is reduced by fuel gas such as CH₄, H₂, CO. And the OC is send to air reactor and oxidized by air or O₂ gas. The oxidation and reduction reaction of OC occurs between the two reactors repeatedly. In the CLC system, high concentration of CO₂ can be easily obtained by steam condensation only from the fuel reactor. It is very important to understand the oxidation and reduction characteristics of oxygen carrier in the CLC system to determine the solids circulation rate between the air and fuel reactors, and the amount of solid bed materials. In this study, we have conducted the experiment and interpreted oxidation and reduction reaction characteristics via observing weight change of Ni-based oxygen carrier using the TGA with varying as concentration and temperature. Characterizations of the oxygen carrier were carried out with BET, SEM. The reaction rate increased with increasing the temperature and increasing the inlet gas concentration. We also compared experimental results and adapted basic reaction kinetic model (JMA model). JAM model is one of the nucleation and nuclei growth models, and this model can explain the delay time at the early part of reaction. As a result, the model data and experimental data agree over the arranged conversion and time with overall variance (R²) greater than 98%. Also, we calculated activation energy, pre-exponential factor, and reaction order through the Arrhenius plot and compared with previous Ni-based oxygen carriers.

Keywords: chemical looping combustion, kinetic, nickel-based, oxygen carrier, spray drying method

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Authors: Young Man Cho, Sang Hyun Kim

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Even though various management practices such as sediment dredging were attempted to improve water quality of Dongcheon located in Busan, the environmental condition of this stream was deteriorated. Therefore, Busan metropolitan city had pumped and diverted sea water to upstream of Dongcheon for several years. This study explored hydraulic characteristics of Dongcheon to configure the best management practice for ecological restoration and water quality improvement of a man-made urban stream. Intensive field investigation indicates that average flow velocities at depths of 20% and 80% from the water surface ranged 5 to 10 cm/s and 2 to 5 cm/s, respectively. Concentrations of dissolved oxygen for all depths were less than 0.25 mg/l during low tidal period. Even though density difference can be found along stream depth, density current seems rarely generated in Dongcheon. Short period of high tidal portion and shallow depths are responsible for well-mixing nature of Doncheon.

Keywords: hydraulic, tidal river, density current, sea water

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Authors: Mamdouh Y. Saleh, Gaber El Enany, Medhat H. Elzahar, Moustafa H. Omran

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The discharge limits of industrial wastewater effluents are subjected to regulations which are getting more restricted with time. A former research occurred in Port Said city studied the efficiency of treating industrial wastewater using the first stage (A-stage) of the multiple-stage plant (AB-system).From the results of this former research, the effluent treated wastewater has high rates of total dissolved solids (TDS) and chemical oxygen demand (COD). The purpose of this paper is to improve the treatment process in removing TDS and COD. So a pilot plant was constructed at wastewater pump station in the industrial area in the south of Port Said. Experimental work was divided into several groups adding powdered limestone with different dosages to wastewater, and for each group wastewater was filtered after being mixed with activated carbon. pH and TSS as variables were also studied. Significant removals of TDS and COD were observed in these experiments showing that using effective adsorbents can aid such removals to a large extent.

Keywords: adsorption, filtration, synthetic wastewater, TDS removal, COD removal

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Authors: Oliver Marunțălu, Elena Elisabeta Manea, Lăcrămioara Diana Robescu, Mihai Necșoiu, Gheorghe Lăzăroiu, Dana Andreya Bondrea

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In order to obtain efficient pollutants removal in small-scale wastewater treatment plants, uniform water flow has to be achieved. The experimental setup, designed for treating high-load wastewater (leachate), consists of two aerobic biological reactors and a lamellar settler. Both biological tanks were aerated by using three different types of aeration systems - perforated pipes, membrane air diffusers and tube ceramic diffusers. The possibility of homogenizing the water mass with each of the air diffusion systems was evaluated comparatively. The oxygen concentration was determined by optical sensors with data logging. The experimental data was analyzed comparatively for all three different air dispersion systems aiming to identify the oxygen concentration variation during different operational conditions. The Oxygenation Capacity was calculated for each of the three systems and used as performance and selection parameter. The global mass transfer coefficients were also evaluated as important tools in designing the aeration system. Even though using the tubular porous diffusers leads to higher oxygen concentration compared to the perforated pipe system (which provides medium-sized bubbles in the aqueous solution), it doesn’t achieve the threshold limit of 80% oxygen saturation in less than 30 minutes. The study has shown that the optimal solution for the studied configuration was the radial air diffusers which ensure an oxygen saturation of 80% in 20 minutes. An increment of the values was identified when the air flow was increased.

Keywords: flow, aeration, bioreactor, oxygen concentration

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Authors: A. Gharaei, R. Karami

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Rutilus frisii Kutum was exposed to various concentrations of mercuric chloride in water to determine its acute toxicity and bioaccumulation. We carried out ten treatments with three replicates and one control for each of the chemicals using the static O. E. C. D. method in 55-liter-tanks each containing 14 fingerlings. During the experiments, the average pH was recorded as 7.8, total hardness was measured to be 255 mg/l, the average water temperature was 27±1 degrees centigrade and dissolved oxygen was 7.2 mg/l. Mean LC50 values of Hgcl2 for juvenile R. frisii kutum with mean weight 1±0.2 gr were 0.102 and 0.86 mgHg/l at 24h and 96h, respectively. The bioaccumulation values during 24h in tissue, kidney, and gill were 1.55, 16.1, and 22.7 mgHg/l, respectively. So, these values during 96h were 2.8, 16.8, and 26.65 mgHg/l, respectively. The bioconcentration factors in tissue, kidney, and gill during 24h were 14.75, 153.39, and 216.11 and so during 96h were 33.8, 198.1, and 313.5 times. These results show that bioaccumulation was highest in the gill and then kidney and tissue, respectively. This study suggested that between mercury concentrations of water with bioaccumulation in tissue more than kidney and gill.

Keywords: HgCl2, LC5096h, bioaccumulation, Rutilus frisii Kutum, Caspian Sea

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Authors: Violina R. Angelova, Mariana N. Perifanova-Nemska, Galina P. Uzunova, Elitsa N. Kolentsova

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Comparative research has been conducted to allow us to determine the accumulation of heavy metals (Pb, Zn and Cd) in the vegetative and reproductive organs of safflower, and to identify the possibility of its growth on soils contaminated by heavy metals and efficacy for phytoremediation. The experiment was performed on an agricultural field contaminated by the Non-Ferrous-Metal Works (MFMW) near Plovdiv, Bulgaria. The experimental plots were situated at different distances (0.1, 0.5, 2.0, and 15 km) from the source of pollution. The contents of heavy metals in plant materials (roots, stems, leaves, seeds) were determined. The quality of safflower oils (heavy metals and fatty acid composition) was also determined. The quantitative measurements were carried out with inductively-coupled plasma (ICP). Safflower is a plant that is tolerant to heavy metals and can be referred to the hyperaccumulators of lead and cadmium and the accumulators of zinc. The plant can be successfully used in the phytoremediation of heavy metal contaminated soils. The processing of safflower seeds into oil and the use of the obtained oil will greatly reduce the cost of phytoremediation.

Keywords: heavy metals, accumulation, safflower, polluted soils, phytoremediation

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Authors: Thendiyath Roshni, Stefano Pagliara

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Block ramps (BR) or rock chutes are eco-friendly natural river restoration structures. BR are made of ramp of rocks and flows over BR develop turbulence and helps in the entrainment of ambient air. These act as natural aerators in river flow and therefore leads to oxygenation of water. As many of the hydraulic structures in rivers, hinders the natural path for aquatic habitat. However, flows over BR ascertains a natural rocky flow and ensures safe and natural movement for aquatic habitat. Hence, BR is considered as a better alternative for drop structures. As water quality is concerned, turbulent and aerated flows over BR or macro-roughness conditions improves aeration and thereby oxygenation. Hence, the objective of this paper is to study the oxygenation in the turbulent flows over BR. Experimental data were taken for a slope (S) of 27.5% for three discharges (Q = 9, 15 and 21 lps) conditions. Air concentration were measured with the help of air concentration probe for three different discharges in the uniform flow region. Oxygen concentration is deduced from the air concentration as ambient air is entrained in the flows over BR. Air concentration profiles and oxygen profiles are plotted in the uniform flow region for three discharges and found that air concentration and oxygen concentration does not show any remarkable variation in properties in the longitudinal profile in uniform flow region. An empirical relation is developed for finding the average oxygen concentration (Oₘ) for S = 27.5% in the uniform flow region for 9 < Q < 21 lps. The results show that as the discharge increases over BR, there is a reduction of oxygen concentration in the uniform flow region.

Keywords: aeration, block ramps, oxygenation, turbulent flows

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Authors: A. Alhelfi, B. Sunden

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Cavitation in cryogenic liquids is widely present in contemporary science. In the current study, we re-examine a previously validated acoustic cavitation model which was developed for a gas bubble in liquid water. Furthermore, simulations of cryogenic fluids including the thermal effect, the effect of acoustic pressure amplitude and the frequency of sound field on the bubble dynamics are presented. A gas bubble (Helium) in liquids Nitrogen, Oxygen and Hydrogen in an acoustic field at ambient pressure and low temperature is investigated numerically. The results reveal that the oscillation of the bubble in liquid Hydrogen fluctuates more than in liquids Oxygen and Nitrogen. The oscillation of the bubble in liquids Oxygen and Nitrogen is approximately similar.

Keywords: cryogenic liquids, cavitation, rocket engineering, ultrasound

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Authors: Hamad Almohamadi, Nabeel H. Alharthi, Abdulrahman Aljabri

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In this study, two-dimensional CuFeOx is deposited on nickel foam for the fabrication of electrocatalyst for oxygen evolution reaction (OER). The in-situ hydrothermal synthesis of CuFeOx in presence of aloe vera extract was found to yield unique nano-rose-like morphology which aided to improve the electrochemical surface area of the electrode. The phytochemical assisted synthesis of CuFeOx using 75% aloe vera extract resulted in improved OER electrocatalytic performance by attaining the overpotential of 310 mV for 50 mA cm−2 and 410 mV for 100 mA cm−2. The electrode also sustained robust stability throughout the 50 h of chronopotentiometry studies under alkaline electrolyte conditions, thus proving to be prospective electrode material for efficient OER in electrochemical water splitting.

Keywords: water splitting, phytochemicals, oxygen evaluation reaction, Tafel's slope, stability

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Authors: Abubakar Dikko

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The research investigates the causes of unemployment in Namibia, Nigeria and South Africa, and the role of Capital Accumulation in reducing the unemployment profile of these economies as proposed by the post-Keynesian economics. This is conducted through extensive review of literature on the NAIRU models and focused on the post-Keynesian view of unemployment within the NAIRU framework. The NAIRU (non-accelerating inflation rate of unemployment) model has become a dominant framework used in macroeconomic analysis of unemployment. The study views the post-Keynesian economics arguments that capital accumulation is a major determinant of unemployment. Unemployment remains the fundamental socio-economic challenge facing African economies. It has been a burden to citizens of those economies. Namibia, Nigeria and South Africa are great African nations battling with high unemployment rates. In 2013, the countries recorded high unemployment rates of 16.9%, 23.9% and 24.9% respectively. Most of the unemployed in these economies comprises of youth. Roughly about 40% working age South Africans has jobs, whereas in Nigeria and Namibia is less than that. Unemployment in Africa has wide implications on households which has led to extensive poverty and inequality, and created a rampant criminality. Recently in South Africa there has been a case of xenophobic attacks which were caused by the citizens of the country as a result of unemployment. The high unemployment rate in the country led the citizens to chase away foreigners in the country claiming that they have taken away their jobs. The study proposes that there is a strong relationship between capital accumulation and unemployment in Namibia, Nigeria and South Africa, and capital accumulation is responsible for high unemployment rates in these countries. For the economies to achieve steady state level of employment and satisfactory level of economic growth and development there is need for capital accumulation to take place. The countries in the study have been selected after a critical research and investigations. They are selected based on the following criteria; African economies with high unemployment rates above 15% and have about 40% of their workforce unemployed. This level of unemployment is the critical level of unemployment in Africa as expressed by International Labour Organization (ILO). The African countries with low level of capital accumulation. Adequate statistical measures have been employed using a time-series analysis in the study and the results revealed that capital accumulation is the main driver of unemployment performance in the chosen African countries. An increase in the accumulation of capital causes unemployment to reduce significantly. The results of the research work will be useful and relevant to federal governments and ministries, departments and agencies (MDAs) of Namibia, Nigeria and South Africa to resolve the issue of high and persistent unemployment rates in their economies which are great burden that slows growth and development of developing economies. Also, the result can be useful to World Bank, African Development Bank and International Labour Organization (ILO) in their further research and studies on how to tackle unemployment in developing and emerging economies.

Keywords: capital accumulation, unemployment, NAIRU, Post-Keynesian economics

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Authors: F. O. Arimoro, F. N. Okonkwo, R. B. Ikomi

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The environmental determinants structuring species richness has been generating interest recently but we still lack an understanding of these patterns in various regions (e.g. Afrotropical), and how seasons help to structure these patterns. Our aim was to assessed the environmental drivers importance in regulating species richness and community structure of fish species. The lchthyofauna assemblage of Warri River, Niger Delta area of Nigeria was studied between August 2013 and July 2014. A total of 1152 individuals representing 43 species in 23 families and 30 genera were caught. Of the 43 species recorded, 67.4%, 53.5% and 67.4% of the species occurred in Stations 1, 2 and 3 respectively. Eight taxa representing 18.6% of the total abundance were ubiquitous. The claroteid, Chrysichthys walkeri and the cichlid, Chromidotilapia guentheri were the most dominant species accounting for 19.2% and 6.0% respectively of the total catch. The species richness and general diversity were relatively higher in station 1 although Jaccard similarity index revealed that stations 1 and 3 were significantly similar while station 2 showed complete dissimilarity with stations 1 and 3. Canonical correspondence analysis indicated that dissolved oxygen, electrical conductivity, total nitrogen, Biochemical Oxygen demand and temperature were important variables structuring the overall fish assemblages. The presence of appreciable number of juveniles in this water body suggests that the Warri River is a breeding and nursery ground for fish species particularly those of brackish origin. These findings indicate that the water body is still useful as a good fishing ground for the rural communities and every effort should be put in place to ensure its protection and conservation for the production of healthy fish.

Keywords: Chrysichthys walkeri, fish communities, mangrove ecosystem, physicochemical parameters, Warri River

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Authors: Peihao Huang, Chun Zhao

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Thin-film transistors(TFTs) have the advantages of low power consumption, short reaction time, and have high research value in the field of semiconductors, based on this reason, people have focused on gallium oxide-indium oxide thin-film transistors, a relatively common thin-film transistor, elaborated and analyzed his production process, "aqueous solution method", explained the purpose of each step of operation, and finally explored the influence of potassium ions doped in the channel layer on the electrical properties of the device, as well as the effect of oxygen vacancies on its switching ratio and memory, and summarized the conclusions.

Keywords: aqueous solution, oxygen vacancies, switch ratio, thin-film transistor(TFT)

Procedia PDF Downloads 79

Authors: Nida Rizvi, Deeksha Katyal, Varun Joshi

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River Hindon is an important river catering the demand of highly populated rural and industrial cluster of western Uttar Pradesh, India. Water quality of river Hindon is deteriorating at an alarming rate due to various industrial, municipal and agricultural activities. The present study aimed at identifying the pollution sources and quantifying the degree to which these sources are responsible for the deteriorating water quality of the river. Various water quality parameters, like pH, temperature, electrical conductivity, total dissolved solids, total hardness, calcium, chloride, nitrate, sulphate, biological oxygen demand, chemical oxygen demand and total alkalinity were assessed. Water quality data obtained from eight study sites for one year has been subjected to the two multivariate techniques, namely, principal component analysis and cluster analysis. Principal component analysis was applied with the aim to find out spatial variability and to identify the sources responsible for the water quality of the river. Three Varifactors were obtained after varimax rotation of initial principal components using principal component analysis. Cluster analysis was carried out to classify sampling stations of certain similarity, which grouped eight different sites into two clusters. The study reveals that the anthropogenic influence (municipal, industrial, waste water and agricultural runoff) was the major source of river water pollution. Thus, this study illustrates the utility of multivariate statistical techniques for analysis and elucidation of multifaceted data sets, recognition of pollution sources/factors and understanding temporal/spatial variations in water quality for effective river water quality management.

Keywords: cluster analysis, multivariate statistical techniques, river Hindon, water quality

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Authors: Farhan Ali

Abstract:

Use of wastewater for growing vegetables has become a common practice around big cities. Wastewater contains organic material and inorganic elements essential for plant growth but also contain heavy metals, which may be lethal for animals and humans if their concentration increases than permissible limit. To monitor this situation, a survey was conducted to ascertain the addition of heavy metals into agricultural fields through wastewater irrigation and their translocation in to the edible parts of the vegetables. The study highlighted that there is a large accumulation of heavy metals in the soil, which is irrigated with industrial wastewater Laden and people consume vegetables grown in soil irrigated with sewage water to absorb a large amount of these metals. This accumulation of heavy metals in food cause possible health risks for the consumer. Regular monitoring of the levels of pathogens and heavy metals from the waste water drain which effluent are used for growing vegetables and other foodstuffs is essential to monitor excessive accumulation of these metals in the food chain.

Keywords: pathogens, wastewater, concentration, effluent

Procedia PDF Downloads 273

Authors: Zhao Bo

Abstract:

The TiO2-Na2SO3 and SiO2-Na2SO3 nano-fluids were prepared using ultrasonic dispertion method without any surfactant addition to study the influence of nano-fluids on the mass transfer during forced sulfite oxidation in a thermostatic stirred tank, and the kinetic viscosity of nano-fluids was measured. The influence of temperature (30 ℃ ~ 50 ℃), solid loading of fine particle (0 Kg/m³~1.0 Kg/m³), stirring speed (50 r/min ~ 400 r/min), and particle size (10 nm~100 nm) on the average oxygen absorption rate were investigated in detail. Both TiO2 nano-particles and SiO2 nano-particles could remarkably improve the gas-liquid mass transfer. Oxygen absorption enhancement factor increases with the increase of solid loading of nano-particles to a critical value and then decreases with further increase of solid loading under 30℃. Oxygen absorption rate together with absorption enhancement factor increases with stirring speed. However, oxygen absorption enhancement factor decreases with the increase of temperature due to aggregation of nano-particles. Further inherent relationship between particle size, loading, surface area, viscosity, stirring speed, temperature, adsorption, desorption, and mass transfer was discussed in depth by analyzing the interaction mechanism.

Keywords: fine particles, nano-fluid, mass transfer enhancement, solid loading

Procedia PDF Downloads 218

Authors: Branimir Skoric

Abstract:

Over the past two decades, number of international travels rose significantly in the United Kingdom and Worldwide in the shape of business travels and holiday travels as well. The fact that elderly people travel a lot, more than ever before increased the needs for medical evacuations (repatriations) back home if they fell ill abroad or had any kind of accident. This paper concerns medical evacuations of patients on the way back home to the United Kingdom (United Kingdom Residents) and their specific medical needs during short-haul or long-haul commercial scheduled flight and ground transportation to the final destination regardless whether it was hospital or usual place of residence. Particular medical need during medical evacuations is oxygen supply and it can be supplied via portable oxygen concentrator, pulse flow oxygenator or continuous free flow oxygenator depending on the main diagnosis and patient’s comorbidities. In this retrospective study, patients were divided into two groups. One group was consisted of patients suffering from cardio-respiratory diagnoses as primary illness. Another Group consisted of patients suffering from noncardiac illnesses who have other problems including any kind of physical injury. Needs for oxygen and type of supply were carefully considered in regards of duration of the flight, standard airline cabin pressure and results described in this retrospective study.

Keywords: commercial flight, elderly travellers, medical evacuations, oxygen

Procedia PDF Downloads 129

Authors: Adedolapo Ayoade, John the Beloved Dada

Abstract:

This study identified the phytoplankton assemblage of the Dandaru Lake (that received effluents from a zoological garden and hospital) as bioindicators of water quality. Physicochemical parameters including Dissolved Oxygen (DO), biochemical oxygen demand, nitrate, phosphate and heavy metals were also determined. Samples of water and plankton were collected once monthly from April to September, 2015 at five stations (I – V). The mean physicochemical parameters were within the limits of National Environmental Standards and Regulations Enforcement Agency (NESREA) and USEPA except Lead, 0.02 ± 0.08 mg/ L; Manganese, 0.46 ± 1.00 mg/ L and Zinc, 0.05 ± 0.17 mg/ L. Means of DO, alkalinity, and phosphate were significantly different between the stations at p < 0.05. While highest mean DO (6.88 ± 1.34 mg/L) was recorded in station I with less anthropogenic activities, highest phosphate concentration (0.28 ± 0.28 mg/L) occurred in station II, the entry point of wastewater from hospital and zoological garden. The 147 phytoplankton species found in the lake belonged to six classes: Chlorophyceae (50), Euglenophyceae (40), Bacillariophyceae (37), Cyanophyceae (17), Xanthophyceae and Chrysophyceae (3). The order of abundance for phytoplankton was Euglenophyceae (49.77%) > Bacillariophyceae (18.00%) > Cyanophyceae (17.39%) > Chlorophyceae (13.7%) > Xanthophyceae (1.06%) > Chrysophyceae (0.02%). The stations impacted with effluents were dominated by members of Euglenophyceae (Station III, 77.09%; IV, 50.55%) and Cyanophyceae (Station II, 27.7%; V, 32.57%). While station I was dominated by diatoms (57.98%). The species richness recorded was 0.32 – 4.49. Evenness index was highest in station I and least in station III. Generally, pollution tolerant species (Microcystis, Oscillatoria, Scenedesmus, Anabaena, and Euglena) showed greater density in areas impacted by human activities. The phytoplankton assemblage and comparatively low biotic diversity in Dandaru Lake could be attributed to perturbations in the water column that exerted selective effects on the biological assemblage.

Keywords: manmade lake, Nigeria, phytoplankton, water quality

Procedia PDF Downloads 233

Authors: Deybith Venegas-Rojas, Jens Budde, Dominik Nörz, Manfred Jücker, Hoc Khiem Trieu

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Microfluidics is a promising approach for biomedicine cell culture experiments with microfluidic bioreactors (MBR), which can provide high precision in volume and time control over mass transport and microenvironments in small-scale studies. Nevertheless, shear stress and oxygen concentration are important factors that affect the microenvironment and then the cell culture. It is presented a novel MBR design in which differences in geometry, shear stress, and oxygen concentration were studied and optimized for cell culture. The aim is to mimic the in vivo condition with biocompatible materials and continuous perfusion of nutrients, a healthy shear stress, and oxygen concentration. The design consists of a capture system of PDMS micropillars which keep cells in place, so it is not necessary any hydrogel or complicated scaffolds for cells immobilization. Besides, the design allows continuous supply with nutrients or even any other chemical for cell experimentation. Finite element method simulations were used to study and optimize the effect of parameters such as flow rate, shear stress, oxygen concentration, micropillars shape, and dimensions. The micropillars device was fabricated with microsystem technology such as soft-lithography, deep reactive ion etching, self-assembled monolayer, replica molding, and oxygen plasma bonding. Eight different geometries were fabricated and tested, with different flow rates according to the simulations. During the experiments, it was observed the effect of micropillars size, shape, and configuration for stability and shear stress control when increasing flow rate. The device was tested with several successful HepG2 3D cell cultures. With this MBR, the aforementioned parameters can be controlled in order to keep a healthy microenvironment according to specific necessities of different cell types, with no need of hydrogels and can be used for a wide range of experiments with cells.

Keywords: cell culture, micro-bioreactor, microfluidics, micropillars, oxygen concentration, shear stress

Procedia PDF Downloads 268