Search results for: nitrate leaching

Authors: M. Grifoni, G. Petruzzelli, M. Barbafieri, I. Rosellini, B. Pezzarossa, F. Pedron

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Evapotranspiration (ET) covers are an alternative cover system that utilizes water balance approach to maximize the ET process to reduce the contaminants leaching through the soil profile. Microcosm tests allow to identify in a short time the most suitable plant species to be used as alternative covers, their survival capacity, and simultaneously the transpiration and evaporation rate of the cover in a specific contaminated soil. This work shows the soil characterization and ET results of microcosm tests carried out on two contaminated soils by using Triticum durum and Helianthus annuus species. The data indicated that transpiration was higher than evaporation, supporting the use of plants as alternative cover at this contaminated site.

Keywords: contaminated sites, evapotranspiration cover, evapotranspiration, microcosm experiments

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Authors: K. L. Kabemba, R. F. Sandenberg

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The usual way to desorb gold is by elution with a hot concentrated alkaline solution of sodium cyanide. The high temperature is necessary because the dielectric constant of water decreases with increasing temperature hence the electrostatic forces between charcoal and the gold cyanide complex decreases. High alkalinity and a high concentration of cyanide are necessary for gold desorption because both OH- and CN- ions are preferentially adsorbed. The rate of elution increases with increasing anion concentration but decreases with increasing cation concentration that means the rate of elution passes through a maximum as the concentration of the eluting salt (NaCN, for example) is increased. The anion that gives the best results, the cyanide ion, decomposes fairly rapidly at elevated temperatures (40% in 6 hours, 90% in 24 hours at 95°C).

Keywords: caustic, cyanide, gold, temperature

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Authors: Hassan Baji, Chun-Qing Li, Wei Yang

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Water seepage is one of the most common causes of damage in tunnel structures, which can cause direct and indirect e.g. reinforcement corrosion and calcium leaching damages. Estimation of water seepage or inflow is one of the main challenges in probabilistic assessment of tunnels. The methodology proposed in this study is an attempt for mathematically modeling the water seepage in tunnel structures and further predicting its service life. Using the time-dependent reliability, water seepage is formulated as a failure mode, which can be used for prediction of service life. Application of the formulated seepage failure mode to a case study tunnel is presented.

Keywords: water seepage, tunnels, time-dependent reliability, service life

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Authors: Adriana Sosa, Susana Rincon, Chérif Ben, Diana Cabañas, Juan E. Ruiz, Alejandro Zepeda

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The complex chemical composition (mixtures of ammonium and recalcitrant compounds) of the effluents from the chemical, pharmaceutical and petrochemical industries represents a challenge in their biological treatment. This treatment involves nitrification process that can suffer an inhibition due to the presence of aromatic compounds giving as a result the decrease of the process efficiency. The inhibitory effects on nitrification in the presence of aromatic compounds have already been studied; however a few studies have considered the presence of phenolic compounds in the form of mixtures, which is the form that they are present in real context. For this reason, we realized a kinetic study on the nitrifying process in the presence of different concentrations of a mixture of phenol, o-cresol, m-cresol and p-cresol (0 - 320 mg C/L) in a sequencing batch reactor (SBR). Firstly, the nitrifying process was evaluated in absence of the phenolic mixture (control 1) in a SBR with 2 L working volume and 176 mg/L of nitrogen of microbial protein. Total oxidation of initial ammonium (efficiency; ENH4+ of 100 %) to nitrate (nitrifying yield; YNO3- of 0.95) were obtained with specific rates of ammonium consumption (qN-NH4+) and nitrate production (qN-NO3-) (of 1.11 ± 0.04 h-1 and 0.67 h-1 ± 0.11 respectively. During the phase of acclimation with 40 mg C/L of the phenolic mixture, an inhibitory effect on the nitrifying process was observed, provoking a decrease in ENH4+ and YNO3- (11 and 54 % respectively) as well as in the specific rates (89 y 46 % respectively), being the ammonia oxidizing bacteria (BAO) the most affected. However, in the next cycles without the phenolic mixture (control 2), the nitrifying consortium was able to recover its nitrifying capacity (ENH4+ = 100% and YNO3-=0.98). Afterwards the SBR was fed with 10 mg C/L of the phenolic mixture, obtaining and ENH4+ of 100%, YNO3- and qN-NH4+ 0.62 ± 0.006 and 0.13 ± 0.004 respectively, while the qN-NO3- was 0.49 ± 0.007. Moreover, with the increase of the phenolic concentrations (10-160 mg C/L) and the number of cycles the nitrifying consortium was able to oxidize the ammonia with ENH4+ of 100 % and YNO3- close to 1. However a decrease in the values of the nitrification specific rates and increase in the oxidation in phenolic compounds (70 to 94%) were observed. Finally, in the presence of 320 mg C/L, the nitrifying consortium was able to simultaneously oxidize the ammonia (ENH4+= 100%) and the phenolic mixture (p-cresol>phenol>m-cresol>o-cresol) being the o-cresol the most recalcitrant compound. In all the experiments the use of a SBR allowed a respiratory adaptation of the consortium to oxidize the phenolic mixture achieving greater adaptation of the nitrite-oxidizing bacteria (NOB) than in the ammonia-oxidizing bacteria (AOB).

Keywords: cresol, inhibition, nitrification, phenol, sequencing batch reactor

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Authors: Diana Puigserver Cuerda, Jofre Herrero Ferran, José M. Carmona Perez

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In the transition zone between aquifers and basal aquitards, DNAPL-pools of chlorinated solvents are more recalcitrant than at other depths in the aquifer. Although degradation of carbon tetrachloride (CT) and chloroform (CF) occurs in this zone, this is a slow process, which is why an adequate remediation strategy is necessary. The working hypothesis of this study is that the biostimulation of the transition zone of an aquifer contaminated by CT and CF can be an effective remediation strategy. This hypothesis has been tested in a site on an unconfined aquifer in which the major contaminants were CT and CF of industrial origin and where the hydrochemical background was rich in other compounds that can hinder natural attenuation of chloromethanes. Field studies and five laboratory microcosm experiments were carried out at the level of groundwater and sediments to identify: i) the degradation processes of CT and CF; ii) the structure of microbial communities; and iii) the microorganisms implicated on this degradation. For this, concentration of contaminants and co-contaminants (nitrate and sulfate), Compound Specific Isotope Analysis, molecular techniques (Denaturing Gradient Gel Electrophoresis) and clone library analysis were used. The main results were: i) degradation processes of CT and CF occurred in groundwater and in the lesser conductive sediments; ii) sulfate-reducing conditions in the transition zone were high and similar to those in the source of contamination; iii) two microorganisms (Azospira suillum and a bacterium of the Clostridiales order) were identified in the transition zone at the field and lab experiments that were compatible with the role of carrying out the reductive dechlorination of CT, CF and their degradation products (dichloromethane and chloromethane); iv) these two microorganisms were present at the high starting concentrations of the microcosm experiments (similar to those in the source of DNAPL) and continued being present until the last day of the lactate biostimulation; and v) the lactate biostimulation gave rise to the fastest and highest degradation rates and promoted the elimination of other electron acceptors (e.g. nitrate and sulfate). All these results are evidence that lactate biostimulation can be effective in remediating the source and plume, especially in the transition zone, and highlight the environmental relevance of the treatment of contaminated transition zones in industrial contexts similar to that studied.

Keywords: Azospira suillum, lactate biostimulation of carbon tetrachloride and chloroform, reductive dechlorination, transition zone between aquifer and aquitard

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Authors: Nisha Dhariwal, Anupama Sharma

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The synthesis of cellulose nanofibrils quaternized with 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride (CHPTAC) in NaOH/urea aqueous solution has been reported. Xylenol Orange (XO) has been used as an indicator for selective detection of Sn (II) ions, by its immobilization on quaternized cellulose membrane. The effects of pH, reagent concentration and reaction time on the immobilization of XO have also been studied. The linear response, limit of detection, and interference of other metal ions have also been studied and no significant interference has been observed. The optical chemical sensor displayed good durability and short response time with negligible leaching of the reagent.

Keywords: cellulose, chemical sensor, heavy metal ions, indicator immobilization

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Authors: Qian Li, Zhaoping Zhong

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Sewage sludge, a typical solid waste, has inevitably been produced in enormous quantities in China. Still worse, the amount of sewage sludge produced has been increasing due to rapid economic development and urbanization. Compared to the conventional method to treat sewage sludge, pyrolysis has been considered an economic and ecological technology because it can significantly reduce the sludge volume, completely kill pathogens, and produce valuable solid, gas, and liquid products. However, the large-scale utilization of sludge biochar has been limited due to the considerable risk posed by heavy metals in the sludge. Heavy metals enriched in pyrolytic biochar could be divided into exchangeable, reducible, oxidizable, and residual forms. The residual form of heavy metals is the most stable and cannot be used by organisms. Kaolin and zeolite are environmentally friendly inorganic minerals with a high surface area and heat resistance characteristics. So, they exhibit the enormous potential to immobilize heavy metals. In order to reduce the risk of leaching heavy metals in the pyrolysis biochar, this study pyrolyzed sewage sludge mixed with kaolin/zeolite in a small rotary kiln. The influences of additives and pyrolysis temperature on the leaching concentration and morphological transformation of heavy metals in pyrolysis biochar were investigated. The potential mechanism of stabilizing heavy metals in the co-pyrolysis of sludge blended with kaolin/zeolite was explained by scanning electron microscopy, X-ray diffraction, and specific surface area and porosity analysis. The European Community Bureau of Reference sequential extraction procedure has been applied to analyze the forms of heavy metals in sludge and pyrolysis biochar. All the concentrations of heavy metals were examined by flame atomic absorption spectrophotometry. Compared with the proportions of heavy metals associated with the F4 fraction in pyrolytic carbon prepared without additional agents, those in carbon obtained by co-pyrolysis of sludge and kaolin/zeolite increased. Increasing the additive dosage could improve the proportions of the stable fraction of various heavy metals in biochar. Kaolin exhibited a better effect on stabilizing heavy metals than zeolite. Aluminosilicate additives with excellent adsorption performance could capture more released heavy metals during sludge pyrolysis. Then heavy metal ions would react with the oxygen ions of additives to form silicate and aluminate, causing the conversion of heavy metals from unstable fractions (sulfate, chloride, etc.) to stable fractions (silicate, aluminate, etc.). This study reveals that the efficiency of stabilizing heavy metals depends on the formation of stable mineral compounds containing heavy metals in pyrolysis biochar.

Keywords: co-pyrolysis, heavy metals, immobilization mechanism, sewage sludge

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Authors: Danilo A. F. Fontes, Magaly A. M.Lyra, Maria L. C. Moura, Leslie R. M. Ferraz, Salvana P. M. Costa, Amanda C. Q. M. Vieira, Larissa A. Rolim, Giovanna C. R. M. Schver, Ping I. Lee, Severino Alves-Júnior, José L. Soares-Sobrinho, Pedro J. Rolim-Neto

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Efavirenz (EFV) is a first-choice drug in antiretroviral therapy with high efficacy in the treatment of infection by Human Immunodeficiency Virus, which causes Acquired Immune Deficiency Syndrome (AIDS). EFV has low solubility in water resulting in a decrease in the dissolution rate and, consequently, in its bioavailability. Among the technological alternatives to increase solubility, the Lamellar Double Hydroxides (LDH) have been applied in the development of systems with poorly water-soluble drugs. The use of analytical techniques such as X-Ray Diffraction (XRD), Infrared Spectroscopy (IR) and Differential Scanning Calorimetry (DSC) allowed the elucidation of drug interaction with the lamellar compounds. The objective of this work was to characterize and develop the binary systems with EFV and LDH in order to increase the solubility of the drug. The LDH-CaAl was synthesized by the method of co-precipitation from salt solutions of calcium nitrate and aluminum nitrate in basic medium. The systems EFV-LDH and their physical mixtures (PM) were obtained at different concentrations (5-60% of EFV) using the solvent technique described by Takahashi & Yamaguchi (1991). The characterization of the systems and the PM’s was performed by XRD techniques, IR, DSC and dissolution test under non-sink conditions. The results showed improvements in the solubility of EFV when associated with LDH, due to a possible change in its crystal structure and formation of an amorphous material. From the DSC results, one could see that the endothermic peak at 173°C, temperature that correspond to the melting process of EFZ in the crystal form, was present in the PM results. For the EFZ-LDH systems (with 5, 10 and 30% of drug loading), this peak was not observed. XRD profiles of the PM showed well-defined peaks for EFV. Analyzing the XRD patterns of the systems, it was found that the XRD profiles of all the systems showed complete attenuation of the characteristic peaks of the crystalline form of EFZ. The IR technique showed that, in the results of the PM, there was the appearance of one band and overlap of other bands, while the IR results of the systems with 5, 10 and 30% drug loading showed the disappearance of bands and a few others with reduced intensity. The dissolution test under non-sink conditions showed that systems with 5, 10 and 30% drug loading promoted a great increase in the solubility of EFV, but the system with 10% of drug loading was the only one that could keep substantial amount of drug in solution at different pHs.

Keywords: Efavirenz, Lamellar Double Hydroxides, Pharmaceutical Techonology, Solubility

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Authors: Finda A. Mahardika, Niken Aristyawati, Retno W. Damayanti

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Improvement technology needed to increase productivity of home industry that make herbal medicine is ginger washer tool. To solve this case, the writers develop existing technologies to create a tool that serves as a wash of ginger. This washer uses pedal tools to help the brush washer move. This tool is expected to produce ginger with good quality. In addition, this tool is also expected to be able to save time as well as water used when conducting the process of leaching. This tool is based on the size of the anthropometri people of Indonesia for the results of an ergonomic. The activities carried out by conducting a study of theory, experiment based on existing theories and make modifications based on the results obtained.

Keywords: ginger, ginger washer, technology, pedal

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Authors: Shashi Kant Verma, S. L. Sinha, D. K. Chandraker

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Numerical simulations of selected subchannel tracer (Potassium Nitrate) based experiments have been performed to study the capabilities of state-of-the-art of Computational Fluid Dynamics (CFD) codes. The Computational Fluid Dynamics (CFD) methodology can be useful for investigating the spacer effect on turbulent mixing to predict turbulent flow behavior such as Dimensionless mixing scalar distributions, radial velocity and vortices in the nuclear fuel assembly. A Gibson and Launder (GL) Reynolds stress model (RSM) has been selected as the primary turbulence model to be applied for the simulation case as it has been previously found reasonably accurate to predict flows inside rod bundles. As a comparison, the case is also simulated using a standard k-ε turbulence model that is widely used in industry. Despite being an isotropic turbulence model, it has also been used in the modeling of flow in rod bundles and to produce lateral velocities after thorough mixing of coolant fairly. Both these models have been solved numerically to find out fully developed isothermal turbulent flow in a 30º segment of a 54-rod bundle. Numerical simulation has been carried out for the study of natural mixing of a Tracer (Passive scalar) to characterize the growth of turbulent diffusion in an injected sub-channel and, afterwards on, cross-mixing between adjacent sub-channels. The mixing with water has been numerically studied by means of steady state CFD simulations with the commercial code STAR-CCM+. Flow enters into the computational domain through the mass inflow at the three subchannel faces. Turbulence intensity and hydraulic diameter of 1% and 5.9 mm respectively were used for the inlet. A passive scalar (Potassium nitrate) is injected through the mass fraction of 5.536 PPM at subchannel 2 (Upstream of the mixing section). Flow exited the domain through the pressure outlet boundary (0 Pa), and the reference pressure was 1 atm. Simulation results have been extracted at different locations of the mixing zone and downstream zone. The local mass fraction shows uniform mixing. The effect of the applied turbulence model is nearly negligible just before the outlet plane because the distributions look like almost identical and the flow is fully developed. On the other hand, quantitatively the dimensionless mixing scalar distributions change noticeably, which is visible in the different scale of the colour bars.

Keywords: single-phase flow, turbulent mixing, tracer, sub channel analysis

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Authors: J. Klofac, P. Bazant, I. Kuritka

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This work is focused on the preparation of polymeric blend composed of polyamide (PA) and polyvinyl alcohol (PVA) with the intention to explore its basic characteristics important for potential use in medicine, especially for drug delivery systems. PA brings brilliant mechanical properties to the blend while PVA is inevitable due to its water solubility. Blend with different PA/PVA ratios were prepared and the release study of PVA into the water was carried out in a time interval 0-48 hours via the gravimetric method. The weight decrease is caused by the leaching of PVA domains what can be also followed by the optical and scanning electron microscopy. In addition, the thermal properties and the miscibility of blend components were evaluated by the differential scanning calorimeter. On the bases of performed experiments, it was found that the kinetics, continuity development and micro structure features of PA/PVA blends is strongly dependent on the blend composition and miscibility of its components.

Keywords: releas study, polyvinyl alcohol, polyamide morphology, polymeric blend

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Authors: F. Ghafoori-Najafabadi, R. Sarraf-Mamoory, N. Riahi-Noori

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In this study, nanocrystalline CeO2-MgO powders were synthesized by combustion reactions using citric acid, ethylene glycol, and glycine as different fuels and nitrate as an oxidant. The powders obtained with different kinds of fuels are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The size and morphology of the particles and the extent of agglomeration in the powders were studied using SEM analysis. It is observed that the variation of fuel has an intense influence on the particle size and morphology of the resulting powder. X-ray diffraction revealed that any combined phases were observed, and that MgO and CeO2 phases were formed, separately.

Keywords: nanoparticle, combustion synthesis, CeO2-MgO, nano-powder

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Authors: N. Mohseni, S. Janitabar, S.J. Ahmadi, M. Roshanzamir, M. Thaghizadeh

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There has been proposed a technique for getting thorium dioxide mesoporous nanocrystalline. In this paper thorium dioxide powder was synthesized through the sol-gel method using hydrated thorium nitrate and ammonium hydroxide as starting materials and Triton X100 as surfactant. ThO2 gel was characterized by thermogravimetric (TG), and prepared ThO2 powder was subjected to scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emett-Teller (BET) analyses studies. Detailed analyses show that prepared powder consisted of phase with the space group Fm3m of thoria and its crystalline size was 27 nm. The thoria possesses 16.7 m2/g surface area and the pore volume and size calculated to be 0.0423 cc/g and 1.947 nm, respectively.

Keywords: mesoporous, nanocrystalline, sol-gel, thoria

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Authors: Nassima Khanfri, Ali Boucenna

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As metallic nanoparticles are increasingly used in many economic sectors, there is interest in the biological and environmental safety of their production. The main methods of synthesizing nanoparticales are chemical and physical approaches that are often expensive and potentially harmful to the environment. The present study is devoted to the possibility of the synthesis of silver nanoparticales and zinc oxide from silver nitrate and zinc acetate using basilica plant extracts. The products obtained are characterized by various analysis techniques, such as UV/V, XRD, MEB-EDX, FTIR, and RAMAN. These analyzes confirm the crystalline nature of AgNps and ZnONps. These crystalline powders having effective biological activities regarding the antioxidant and antibacterial, which could be used in several biological applications.

Keywords: green synthesis, bio-reduction, metals nan Oparticales, Plants extracts

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Authors: F. Madani, M. Doudi, L. Rahimzadeh Torabi

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The irregular consumption of current antibiotics contributes to an escalation in antibiotic resistance among urinary pathogens on a global scale. The objective of this research was to investigate the process of biologically synthesized silver nanoparticles through the utilization of Zataria multiflora extract. Additionally, the study aimed to evaluate the efficacy of these synthesized nanoparticles in inhibiting the growth of multi-drug resistant negative bacillus bacteria, which commonly contribute to urinary tract infections. The botanical specimen utilized in the current research investigation was Z. multiflora, and its extract was produced employing the Soxhlet extraction technique. The study examined the green synthesis conditions of silver nanoparticles by considering three key parameters: the quantity of extract used, the concentration of silver nitrate salt, and the temperature. The particle dimensions were ascertained using the Zetasizer technique. In order to identify synthesized Silver nanoparticles TEM, XRD, and FTIR methods were used. For evaluating the antibacterial effects of nanoparticles synthesized through a biological method, different concentrations of silver nanoparticles were studied on 140 cases of Multiple drug resistance (MDR) bacteria strains Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Proteus vulgaris,Citrobacter freundii, Acinetobacter bumanii and Pseudomonas aeruginosa, (each genus of bacteria, 20 samples), which all were MDR and cause urinary tract infections, for identification of bacteria were used of PCR test and laboratory methods (Agar well diffusion and Microdilution methods) to assess their sensitivity to Nanoparticles. The data were subjected to analysis using the statistical software SPSS, specifically employing nonparametric Kruskal-Wallis and Mann-Whitney tests. This study yielded noteworthy findings regarding the impacts of varying concentrations of silver nitrate, different quantities of Z. multiflora extract, and levels of temperature on nanoparticles. Specifically, it was observed that an increase in the concentration of silver nitrate, extract amount, and temperature resulted in a reduction in the size of the nanoparticles synthesized. However, the impact of the aforementioned factors on the index of particle diffusion was found to be statistically non-significant. According to the transmission electron microscopy (TEM) findings, the particles exhibited predominantly spherical morphology, with a diameter spanning from 25 to 50 nanometers. Nanoparticles in the examined sample. Nanocrystals of silver. FTIR method illustrated that the spectrums of Z. multiflora and synthesized nanoparticles had clear peaks in the ranges of 1500-2000, and 3500 - 4000. The obtained results of antibacterial effects of different concentrations of silver nanoparticles on according to agar well diffusion and microdilution method, biologically synthesized nanoparticles showed 1000 mg /ml highest and lowest mean inhibition zone diameter in E. coli, A. bumanii 23 and 15mm, respectively. MIC was observed for all of bacteria 125 mg/ml and for A. bumanii 250 mg/ml. Comparing the growth inhibitory effect of chemically synthesized the results obtained from the experiment indicated that both nanoparticles and biologically synthesized nanoparticles exhibit a notable growth inhibition effect. Specifically, the chemical method of synthesizing nanoparticles demonstrated the highest level of growth inhibition at a concentration of 62.5 mg/mL The present study demonstrated an inhibitory effect on bacterial growth, facilitating the causative factors of urine infection and multidrug resistance (MDR).

Keywords: multiple drug resistance, negative bacillus bacteria, urine infection, Zataria multiflora

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Authors: M. Tammaro, S. Manzo, J. Rimauro, A. Salluzzo, S. Schiavo

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The solar photovoltaic (PV) modules are considered to have a negligible environmental impact compared to the fossil energy. Therefore also the waste management and the corresponding potential environmental hazard needs to be considered. The case of the photovoltaic panel is unique because the time lag from the manufacturing to the decommissioning as waste usually takes 25-30 years. Then the environmental hazard associated with end life of PV panels has been largely related to their metal contents. The principal concern regards the presence of heavy metals as Cd in thin film (TF) modules or Pb and Cr in crystalline silicon (c-Si) panels. At the end of life of PV panels, these dangerous substances could be released in the environment, if special requirements for their disposal are not adopted. Nevertheless, in literature, only a few experimental study about metal emissions from silicon crystalline/thin film panels and the corresponding environmental effect are present. As part of a study funded by the Italian national consortium for the waste collection and recycling (COBAT), the present work was aimed to analyze experimentally the potential release into the environment of hazardous elements, particularly metals, from PV waste. In this paper, for the first time, eighteen releasable metals a large number of photovoltaic panels, by c-Si and TF, manufactured in the last 30 years, together with the environmental effects by a battery of ecotoxicological tests, were investigated. Leaching tests are conducted on the crushed samples of PV module. The test is conducted according to Italian and European Standard procedure for hazard assessment of the granular waste and of the sludge. The sample material is shaken for 24 hours in HDPE bottles with an overhead mixer Rotax 6.8 VELP at indoor temperature and using pure water (18 MΩ resistivity) as leaching solution. The liquid-to-solid ratio was 10 (L/S=10, i.e. 10 liters of water per kg of solid). The ecotoxicological tests were performed in the subsequent 24 hours. A battery of toxicity test with bacteria (Vibrio fisheri), algae (Pseudochirneriella subcapitata) and crustacea (Daphnia magna) was carried out on PV panel leachates obtained as previously described and immediately stored in dark and at 4°C until testing (in the next 24 hours). For understand the actual pollution load, a comparison with the current European and Italian benchmark limits was performed. The trend of leachable metal amount from panels in relation to manufacturing years was then highlighted in order to assess the environmental sustainability of PV technology over time. The experimental results were very heterogeneous and show that the photovoltaic panels could represent an environmental hazard. The experimental results showed that the amounts of some hazardous metals (Pb, Cr, Cd, Ni), for c-Si and TF, exceed the law limits and they are a clear indication of the potential environmental risk of photovoltaic panels "as a waste" without a proper management.

Keywords: photovoltaic panel, environment, ecotoxicity, metals emission

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Authors: Vasiliki Kolake, Christos Kavalaris, Sofia Megoudi, Maria Maxouri, Panagiotis A. Karas, Aris Kyparissis, Efi Levizou

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Conservation agriculture (CA), is a production system approach that can tackle the challenges of climate change mainly through facilitating carbon storage into the soil and increasing crop resilience. This is extremely important for the vulnerable Mediterranean agroecosystems, which already face adverse environmental conditions. The agronomic practices used in CA, i.e. permanent soil cover and no-tillage, result in reduced soil erosion and increased soil organic matter, preservation of water and improvement of quality and fertility of the soil in the long-term. Thus the functional characteristics and processes of the soil are considerably affected by the implementation of CA. The aim of the present work was to assess the effects of CA on soil nitrification potential and mycorrhizal colonization about the above-ground production in a wheat field. Two adjacent but independent field sites of 1.5ha each were used (Thessaly plain, Central Greece), comprising the no-till and conventional tillage treatments. The no-tillage site was covered by residues of the previous crop (cotton). Potential nitrification and the nitrate and ammonium content of the soil were measured at two different soil depths (3 and 15cm) at 20-days intervals throughout the growth period. Additionally, the leaf area index (LAI) was monitored at the same time-course. The mycorrhizal colonization was measured at the commencement and end of the experiment. At the final harvest, total yield and plant biomass were also recorded. The results indicate that wheat yield was considerably favored by CA practices, exhibiting a 42% increase compared to the conventional tillage treatment. The superior performance of the CA crop was also depicted in the above-ground plant biomass, where a 26% increase was recorded. LAI, which is considered a reliable growth index, did not show statistically significant differences between treatments throughout the growth period. On the contrary, significant differences were recorded in endomycorrhizal colonization one day before the final harvest, with CA plants exhibiting 20% colonization, while the conventional tillage plants hardly reached 1%. The on-going analyses of potential nitrification measurements, as well as nitrate and ammonium determination, will shed light on the effects of CA on key processes in the soil. These results will integrate the assessment of CA impact on certain below and above-ground processes during wheat cultivation under the Mediterranean climate.

Keywords: conservation agriculture, LAI, mycorrhizal colonization, potential nitrification, wheat, yield

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Authors: Marine Shavlakadze

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Hydroponic greenhouses systems (production of the artificial substrate without soil) are becoming popular in the world. Mostly the system is used to grow vegetables and berries. Different countries are taking action to participate in the development of hydroponic technology and solutions such as EU members, Turkey, Australia, New Zealand, Israel, Scandinavian countries, etc. Many vegetables and berries are grown by hydroponics in Europe. As a result of our research, we have obtained material containing manganese and nitrogen. It became possible to produce this fertilizer by means of one-stage thermal processing, using industrial waste containing manganese (ores and sludges) and mineral substance (ammonium nitrate) that exist in Georgia. The received material is usable as a micro-fertilizer with economic efficiency. It became possible to turn practically water-insoluble manganese dioxide substance into the soluble condition from industrial waste in an indirect way. The ability to use the material as a fertilizer is predetermined by its chemical and phase composition, as the amount of the active component of the material in relation to manganese is 30%. At the same time, the active component elements presented non-ballast sustained action compounds. The studies implemented in Poland and in Georgia by us have shown that the manganese-containing micro-fertilizer- Mn(NO₃)₂ can provide the plant with nitrate nitrogen, which is a form that can be used for plants, providing the economy and simplicity of the application of fertilizers. Given the fact that the application of the manganese-containing micro-fertilizers significantly increases the productivity and improves the quality of the big number of agricultural products, it is necessary to mention that it is recommended to introduce the manganese containing fertilizers into the following cultures: sugar beet, corn, potato, vegetables, vine grape, fruit, berries, and other cultures. Also, as a result of the study, it was established that the material obtained is the predominant fertilizer for vegetable cultures in the soil. Based on the positive results of the research, we consider it expedient to conduct research in hydroponic systems, which will enable us to provide plants the required amount of manganese; we also introduce nitrogen in solution and regulate the solution of pH, which is one of the main problems in hydroponic production. The findings of our research will be used in hydroponic greenhouse farms to increase the fertility of vegetable crops and, consequently, to get bountiful and high-quality harvests, which will promote the development of hydroponic greenhouses in Georgia as well as abroad.

Keywords: hydroponics, micro-fertilizers, manganese-containing materials, industrial wastes

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Authors: Martina Kovalcikova, Adriana Estokova

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Today, concrete belongs to the most frequently used materials in the civil engineering industry for many years. Consuming energy in cement industry is very high and CO₂ emissions generated during the production of Portland cement has serious environmental threatens. Therefore, utilization of pozzolanic material as a supplementary cementitious material has a direct relationship with the sustainable development. The paper presents the results of the comparative study of the resistance of the Slovak origin zeolite based cement composites with addition of silica fume exposed to the sulfate environment. The various aggressive media were used for the experiment: sulfuric acid with pH 4, distilled water and magnesium sulfate solution with a concentration of 3 g/L of SO₄²−. The laboratory experiment proceeded during 180 days under model conditions. The changes in the elemental concentrations of calcium and silicon in liquid leachates were observed.

Keywords: concrete, leaching, silica fume, sulfuric acid, zeolite

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Authors: Ali W. Alattabi, Khalid S. Hashim, Hassnen M. Jafer, Ali Alzeyadi

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This study was performed to optimise the react time (RT) and study its effects on the removal rates of nitrogen compounds in a sequencing batch reactor (SBR) treating synthetic industrial wastewater. The results showed that increasing the RT from 4 h to 10, 16 and 22 h significantly improved the nitrogen compounds’ removal efficiency, it was increased from 69.5% to 95%, 75.7 to 97% and from 54.2 to 80.1% for NH₃-N, NO₃-N and NO₂-N respectively. The results obtained from this study showed that the RT of 22 h was the optimum for nitrogen compounds removal efficiency.

Keywords: ammonia-nitrogen, retention time, nitrate, nitrite, sequencing batch reactor, sludge characteristics

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Authors: O. I. Ojo, W. B. R. Graham, I. W. Pishiria

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The quality of groundwater used for irrigation in Kebbi State, northwestern Nigeria was evaluated. Open-well, tube-well and borehole water samples were collected from various locations in the State. The water samples analyzed had pH values below the normal range for irrigation water and very low to moderate salinity (electrical conductivity 0.05-0.82 dS.m-1). The adjusted sodium adsorption ratio values in all the samples were also very low (<0.2), indicating very low sodicity hazards. However, irrigation water of very low salinity (<0.2dS.m-1) and low SAR can lead to problems of infiltration into soils. The Ca: Mg ratio (<1) in most of the samples may lead to Ca deficiency in soils after long term use. The nitrate concentration in most of the samples was high ranging from 4.5 to >50mg/L.

Keywords: ground water quality, irrigation, characteristics, soil drainage, salinity, Fadama

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Authors: Fatima Zahra Mahjoubi, Abderrahim Khalidi, Mohamed Abdennouri, Omar Cherkaoui, Noureddine Barka

Abstract:

Industrial effluents are one of the major causes of environmental pollution, especially effluents discharged from various dyestuff manufactures, plastic, and paper making industries. These effluents can give rise to certain hazards and environmental problems for their highly colored suspended organic solid. Dye effluents are not only aesthetic pollutants, but coloration of water by the dyes may affect photochemical activities in aquatic systems by reducing light penetration. It has been also reported that several commonly used dyes are carcinogenic and mutagenic for aquatic organisms. Therefore, removing dyes from effluents is of significant importance. Many adsorbent materials have been prepared in the removal of dyes from wastewater, including anionic clay or layered double hydroxyde. The zinc/aluminium (Zn-AlNO₃), magnesium/aluminium (Mg-AlNO₃) and nickel/aluminium (Ni-AlNO₃) layered double hydroxides (LDHs) were successfully synthesized via coprecipitation method. Samples were characterized by XRD, FTIR, TGA/DTA, TEM and pHPZC analysis. XRD patterns showed a basal spacing increase in the order of Zn-AlNO₃ (8.85Å)> Mg-AlNO₃ (7.95Å)> Ni-AlNO₃ (7.82Å). FTIR spectrum confirmed the presence of nitrate anions in the LDHs interlayer. The TEM images indicated that the Zn-AlNO3 presents circular to shaped particles with an average particle size of approximately 30 to 40 nm. Small plates assigned to sheets with hexagonal form were observed in the case of Mg-AlNO₃. Ni-AlNO₃ display nanostructured sphere in diameter between 5 and 10 nm. The LDHs were used as adsorbents for the removal of methyl orange (MO), as a model dye and for the treatment of an effluent generated by a textile factory. Adsorption experiments for MO were carried out as function of solution pH, contact time and initial dye concentration. Maximum adsorption was occurred at acidic solution pH. Kinetic data were tested using pseudo-first-order and pseudo-second-order kinetic models. The best fit was obtained with the pseudo-second-order kinetic model. Equilibrium data were correlated to Langmuir and Freundlich isotherm models. The best conditions for color and COD removal from textile effluent sample were obtained at lower values of pH. Total color removal was obtained with Mg-AlNO₃ and Ni-AlNO₃ LDHs. Reduction of COD to limits authorized by Moroccan standards was obtained with 0.5g/l LDHs dose.

Keywords: chemical oxygen demand, color removal, layered double hydroxides, textile wastewater treatment

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Authors: Saman Javadi, Mehdi Hashemy, Mohahammad Mahmoodi

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Vulnerability maps are employed as an important solution in order to handle entrance of pollution into the aquifers. The common way to provide vulnerability map is DRASTIC. Meanwhile, application of the method is not easy to apply for any aquifer due to choosing appropriate constant values of weights and ranks. In this study, a new approach using k-means clustering is applied to make vulnerability maps. Four features of depth to groundwater, hydraulic conductivity, recharge value and vadose zone were considered at the same time as features of clustering. Five regions are recognized out of the case study represent zones with different level of vulnerability. The finding results show that clustering provides a realistic vulnerability map so that, Pearson’s correlation coefficients between nitrate concentrations and clustering vulnerability is obtained 61%.

Keywords: clustering, data mining, groundwater, vulnerability assessment

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Authors: Aicha Bensouici, Assia Mili, Naouel Rdjem, Nacera Baali

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Copper oxide decorated reduced graphene oxide (GO) was obtained successfully using two steps route synthesis was used. Firstly, graphene oxide was obtained using a modified Hummers method by excluding sodium nitrate from starting materials. After washing-centrifugation routine pristine GO was decorated by copper oxide using a refluxation technique at 120°C during 2h, and an equal amount of GO and copper acetate was used. Three CuO-rGO nanocomposite samples types were obtained at 30min, 24h, and 7 day stirring time. TAC results show dose dependent behavior of CuO-rGO and confirm no influence of stirring time on antioxidant properties, 30min is considered as an optimal stirring condition.

Keywords: copper oxide, reduced graphene oxide, TAC, GO

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Authors: Hang Tran, Victor Brial, Luca Sorelli, Claudiane Ouellet-Plamondon, David Conciatori, Laurent Birry

Abstract:

Spend pot lining (SPL) is a by-product generated from primary aluminum production. SPL consists of two parts, the first cut is rich in carbonaceous materials, and the second cut is rich in aluminum and silicon oxides. After treating by the hydrometallurgical Low Caustic Leaching and Liming process, the refractory part of SPL becomes an inert material, called LCLL ash in this project. LCLL ash was calcined at different temperatures (800 and 1000°C) and Calcined LCLL ash ground as fines of cement and replacement a part of cement in concrete production. The effect of LCLL ash on the chemical properties, mechanical properties and fresh behavior of concrete was evaluated by isothermal calorimetry, compressive test, and slump test. These results were compared to the reference mixture.

Keywords: spend pot lining, concrete, cement, compressive strength, calorimetry

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Authors: Meena Marafi, Mohan S. Rana

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Catalysts play an important role in producing valuable fuel products in petroleum refining; but, due to feedstock’s impurities catalyst gets deactivated with carbon and metal deposition. The disposal of spent catalyst falls under the category of hazardous industrial waste that requires strict agreement with environmental regulations. The spent hydroprocessing catalyst contains Mo, V and Ni at high concentrations that have been found to be economically significant for recovery. Metal recovery process includes deoiling, decoking, grinding, dissolving and treatment with complexing leaching agent such as ethylene diamine tetra acetic acid (EDTA). The process conditions have been optimized as a function of time, temperature and EDTA concentration in presence of ultrasonic agitation. The results indicated that optimum condition established through this approach could recover 97%, 94% and 95% of the extracted Mo, V and Ni, respectively, while 95% EDTA was recovered after acid treatment.

Keywords: atmospheric residue desulfurization (ARDS), deactivation, hydrotreating, spent catalyst

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Authors: Naveed Ejaz, Liaqat Ali, Amer Nusair

Abstract:

Thermal barrier coatings (TBCs) serve as thermal barriers against the high temperature of the hot regions of the aircraft turbine engines keeping the surface of the turbine blades, vanes and combustion chamber at comparatively lower temperature. The life of these coatings depends on many in-service environmental factors. Among these factors, the behavior of the bond coat as well as the top coat at high temperature aggravated by the corrosive environments having S, V, Na and Cl plays a key role. The incorporation of the 5-15% CaZrO3 in YSZ coatings was studied after hot corrosion in vanadium oxide environment. It was observed that the reactivity of the V gradually switched from Y to Ca making CaV2O4 instead of YVO4; the percentage of CaV2O4 increased with the increase of CaZrO3 in YSZ. It eventually prevented leaching out of the Y from YSZ leaving the YSZ without any harmful phase change. The thermal insulation was found to be improved in case of CaZrO3 incorporated YSZ coatings as compared to only YSZ coating.

Keywords: hot corrosion, thermal barrier coatings, yttria stabilized zirconia, calcium zirconate

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Authors: M. Chiliza, H. P. Mbukwane, P Masita, H. Rutto

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Acid mine drainage (AMD) one of the main pollutants of water in many countries that have mining activities. AMD results from the oxidation of pyrite and other metal sulfides. When these metals gets exposed to moisture and oxygen, leaching takes place releasing sulphate and Iron. Acid drainage is often noted by 'yellow boy,' an orange-yellow substance that occurs when the pH of acidic mine-influenced water raises above pH 3, so that the previously dissolved iron precipitates out. The possibility of using environmentally friendly silane and phosphate based coatings on pyrite to remediate acid mine drainage and prevention at source was investigated. The results showed that both coatings reduced chemical oxidation of pyrite based on Fe and sulphate release. Furthermore, it was found that silane based coating performs better when coating synthesis take place in a basic hydrolysis than in an acidic state.

Keywords: acid mine drainage, pyrite, silane, phosphate

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Authors: A. Salemi Golezania, A. Sharifi Fateha

Abstract:

In this study a nano-composite catalyst was synthesized by incorporation of chromium into the framework of MCM-41 as a base catalyst. Mesoporous silica molecular sieves MCM-41 were synthesized under Hydrothermal Continues pH Adjusting Path Way. Then, MCM-41 was impregnated by chromium nitrate aqueous solution for several times under water aspiration. Raw powder was cured by heat treatment in vacuum furnace at 500°C. Phase formation, morphology and gas absorption properties of resulted materials were characterized by XRD, TEM and BET analysis, respectively. The results showed that high quality hexagonal meso structure as a matrix and Cr as a second phase has been formed with a narrow size pore diameter distribution and high surface area in Cr/MCM-41 nano-composite structure. The specific surface and total volume of porosity of the synthesized nanocomposite are obtained 931m^2/gr and 1.12 cm^3/gr, respectively.

Keywords: nano-catalyst, MCM-41, Cr/MCM-41, Marine Science and Engineering

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Authors: A. K. Singh, Chhotu Ram

Abstract:

The present work relates to the corrosivity of distillery effluent and corrosion performance of mild steel and stainless steels SS304L, SS316L, and 2205. The report presents the results and conclusions drawn on the basis of (i) electrochemical polarization tests performed in distillery effluent and laboratory prepared solutions having composition similar to that of the effluent (ii) the surface examination by scanning electron microscope (SEM) of the corroded steel samples. It is observed that pH and presence of chloride, phosphate, calcium, nitrite and nitrate in distillery effluent enhance corrosion, whereas presence of sulphate and potassium inhibits corrosion. Among the materials tested, mild steel is observed to experience maximum corrosion followed by stainless steels SS304L, SS316L, and 2205.

Keywords: corrosion, distillery effluent, electrochemical polarization, steel

Procedia PDF Downloads 384