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Kinetic Analysis for Biodesulfurization of Dibenzothiophene using R. rhodochrous Adsorbed on Silica

Abstract

Experimental biodesulfurization (BDS) data for dibenzothiophene (DBT) (1.0-7.0 mM) with Rhodococcus rhodochorus immobilized by adsorption on silica, were adjusted with liquid-film kinetic model (Fisher coefficient, F = 592.74 and probability value p << 0.05 and r 2 = 0.97). Simulations predict the presence of considerable amounts of DBT surrounding the particles, which would be available for the cells adsorbed on the surface of silica. The greatest percentage removal (50 %) was obtained for adsorbed cell system over the suspended bacterial cells (30 %), showing that sulfur substrates are more bioavailable when the bacterial cells are adsorbed on silica. The liquid-film modelling with diffusional effects provides proper theoretical basis to explain the BDS performance obtained using adsorbed cells.

Open access
Mushrooms as Biomonitors of Heavy Metals Contamination in Forest Areas

Abstract

The aim of the research was to assess the level of contamination with heavy metals (manganese, iron, nickel, copper, zinc, cadmium and lead) in two forest areas selected in different places in Poland: the first one in the Swietokrzyskie Province (forests of the Staporkow Forest Division) and the second one in the Opolskie Province (forests of the Kup Forest Division). The degree of contamination of these forest areas with analytes was found using edible large-fruited mushrooms naturally occurring there - the research was carried out using passive biomonitoring method. Heavy metals in mushrooms (separately in stems and hats) as well as in soil samples were determined by atomic absorption spectrometry with excitation in flame (F-AAS). The obtained results were interpreted by assessing the degree of contamination of forest areas on the basis of concentrations of heavy metals in mushrooms. The obtained results indicate an increased accumulation of heavy metals in hats than in mushrooms stems. On the basis of the obtained data, significant contamination of forest areas with selected heavy metals was also found. This is confirmed by the possibility of using mushrooms as biomonitors in passive biomonitoring of forest areas, which are heavy metal accumulators. In the interpretation of the test results, the phytocumuling factor (PF) was also used. The degree of accumulation of heavy metals, from given forest areas - from soil to mushrooms - was assessed on the basis of determined PF coefficients. In addition, good bioavailability of the analysed analytes by mushrooms was found. Additionally, on the basis of the conducted studies, the possibility of mushroom consumption was assessed - they are not suitable for consumption due to the fact that the permissible concentration standards of heavy metals contained in mushrooms were exceeded.

Open access
Soybean Seedlings Enriched with Iron and Magnesium - Impact on Germination, Growth and Antioxidant Properties

Abstract

Iron (Fe) and magnesium (Mg) deficiency in human diets is a widespread problem observed in various regions of the world. Insufficient Fe uptake results in the development of iron dependent anaemia and depressed physical and intellectual performance. In turn Mg deficiency is associated with alterations in neuromuscular and cardiovascular systems. An emerging alternative to traditional supplementation of these elements in the form of pills, liquids or effervescent tablets, is introduction of fortified food products. In present study we show that preincubation of soybean seeds in Fe and Mg solutions leads to elevated content of these elements in the seedlings. Importantly the pretreatment did not affect germination rate, seedlings growth or, with an exception of Fe supplementation at highest concentration, antioxidant capacity. The obtained results indicate that preincubation of seeds in Fe and Mg solutions may be a promising method of obtaining enriched soybean sprouts.

Open access
Active Moss Biomonitoring of Trace Elements Air Pollution in Chisinau, Republic of Moldova

Abstract

For the first time active moss biomonitoring was used to assess trace element deposition in the capital of the Republic of Moldova, Chisinau. Moss Sphagnum girgensohnii samples were exposed in bags at three sites of Chisinau from October, 2016 to March, 2017. The content of 30 elements: Na, Mg, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Br, Rb, Mo, Sr, Sb, Ba, La, Ce, Cs, Hf, Th, Cu, Cd, Pb, and U in the exposed and unexposed mosses was determined by neutron activation analysis and atomic absorption spectrometry. According to the relative accumulation factor, the most abundant elements in the samples were V, Cr, Fe, Ba, La, As, Sb, U, and Pb. Such elements as Cl, K, and Rb were depleted from the moss tissue during the time of exposure. Principal component analysis was used to identify and characterize different pollution sources. The obtained results indicate that the use of S. girgensohnii moss bags is a simple and inexpensive technique to monitor major and trace element content in the air of urban area.

Open access
Characteristics of Polymeric Ultrafiltration Membranes Produced with the Use of Graphene Oxide

Abstract

This article describes a method for producing polymeric membranes by adding carbon nanostructures in the form of graphene oxide (GO). The reference membrane (having typical composition) was formed via phase inversion, using polyvinylidene fluoride (PVDF) dissolved in dimethylacetamide (DMAC). The polymeric matrix was additionally enriched with a plasticizer, i.e. polyethylene glycol (PEG). Afterwards, graphene oxide ultrasonically dispersed in dimethylacetamide was added to basic matrix. The membranes were further compared with one another by measuring their contact angle and hydrodynamics. The results were compared with the literature reports. The transport properties of the membranes were assessed with experimental ultrafiltration equipment (KOCH Membrane System). Also, their permeate flux and mass transfer resistance were determined.

Open access
Detection of Wastewater Treatment Process Disturbances in Bioreactors Using the E-Nose Technology

Abstract

Wastewater treatment processes are subject to numerous disturbances during biological treatment of wastewater. In order to achieve and sustain suitable conditions of the process, basic wastewater parameters should be frequently monitored. While great improvements have been made in the automatization of treatment process, little is known about automatic measuring systems that can detect unusual process conditions in a bioreactor. Tracking these parameters can be difficult and the time required for the determination might vary from several minutes to few days. The objective of this study is to evaluate the use of an electronic nose in-house device (based on a non-selective gas sensor array) for the detection of process disturbances in a lab-scale sequencing batch reactor (SBR) during biological treatment of wastewater with activated sludge. Measurements were performed during a 12-hours working cycle. Continuous analyses of the headspace were performed using a sensor array based on the resistive Metal Oxide Semiconductor type (MOS) gas sensor. Based on the data obtained and the PCA analysis, this study showed that the e-nose technology can be used to predict or retrieve information about potential disruptions during wastewater processes using the e-nose technology.

Open access
The Effect of Cadmium on Oxidative Stress in Beta vulgaris

Abstract

As a heavy metal, cadmium has strongly toxic effects on plants and can induce oxidative stress. It is absorbed by the roots and transported to the stems and leaves. The aim of the study was to evaluate the effect of various concentrations of cadmium on the metabolic activity of Beta vulgaris and assess the dependence of these processes on the content of metal in the plants. To demonstrate the effect of cadmium on metabolism, protein and photosynthetic pigment content, lipid peroxidation, and the activity of enzymes specific for oxidative stress in roots and shoots were measured. Seeds of B. vulgaris were treated with different concentrations of Cd supplied via a CdCl2 solution: 0 (control), 200, 300 and 400 mg/dm3. Results of the present study revealed increased GPOX activity as cadmium concentration rose, while SOD activity was stimulated by a low Cd concentration (200 mg/dm3) and reduced by high levels of Cd. Based on the present findings, it can be concluded that GPOX in B. vulgaris played a more important role in ROS scavenging than SOD did and was able to reduce the level of lipid peroxidation in plants. Cadmium, in the concentration range used, did not show any significant effect on protein or photosynthetic pigment content.

Open access
Emission of Greenhouse Gases and Odorants from Pig Slurry - Effect on the Environment and Methods of its Reduction

Abstract

Pig slurry is classified as a natural liquid fertilizer, which is a heterogeneous mixture of urine, faeces, remnants of feed and technological water, used to remove excrement and maintain the hygiene of livestock housing. The storage and distribution of pig slurry on farmland affect the environment as they are associated with, among others, the emission of various types of gaseous pollutants, mainly CH4, CO2, N2O, NH3, H2S, and other odorants. Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) are greenhouse gases (GHGs) which contribute to climate change by increasing the greenhouse effect. Ammonia (NH3) and hydrogen sulfide (H2S) are malodorous gases responsible for the occurrence of odour nuisance which, due to their toxicity, may endanger the health and lives of humans and animals. NH3 also influences the increase of atmosphere and soil acidification. The article presents the environmental impact of greenhouse gases and odorous compounds emitted from pig slurry. Key gaseous atmospheric pollutants such as NH3, H2S, CH4, CO2 and N2O have been characterized. Furthermore, methods to reduce the emission of odours and GHGs from pig slurry during its storage and agricultural usage have been discussed.

Open access
Heavy Metal Adsorption by Dewatered Iron-Containing Waste Sludge

Abstract

Drinking water treatment plants produce significant amounts of waste sludge. In this study, removal of Nickel ion by use of wastewater sludge was aimed. The adsorption capability of waste sludge was optimized with varying physical parameters such as pH, adsorbent dosage, adsorbate concentration, contact time, shaking speed and temperature. Initial concentration was set as 25 mg/dm3, absorbent dose was set as 0.3 g/cm3, and temperature was set as 25 °C. Compliance of balance data with Langmuir, Freundlich, Temkin and D-R isotherm models was investigated. The highest R 2 values were obtained with Freundlich isotherm (R 2 = 0.92-0.95). Adsorption kinetics was analysed using pseudo-first order, pseudo-second order, Weber and Morris intraparticle diffusion and Elovich kinetic models, and the system was found to be in a better compliance with pseudo-second order kinetic model. Iron sludge was used as sorbent, and accordingly total iron ion measurements were carried out to determine its possible effects on water. Additionally, SEM, EDX, FTIR spectroscopy, XRD spectrum and atomic force microscope (AFM) measurements were conducted to determine the interaction between the sorbent and metal ions, in addition to characterization of the sorbent. As indicated by research results, drinking water treatment sludge proved to be a potential adsorbent for removal of nickel(II) ions from the solution.

Open access
Investigation of the Influence of Hydrogel Amendment on the Retention Capacities of Green Roofs

Abstract

Progressive economic development as well as urbanisation influence the characteristics of the stormwater runoff. Progressive sealing of drainage basin surface prompts the decrease of rainwater infiltration, thus increasing the runoff intensity. This results in an increase of flood risk. Thus, in urban areas the sustainable urban drainage systems (SUDS) are used in addition to the traditional sewer systems. The examples of SUDS strategy are, inter alia, the roofs covered with vegetation (the green roofs). The paper presents the results of research of retention capacities of 4 diverse green roof models with following growing media: (1) the typical green roof substrate without any additions, (2) the substrate with addition of about 1 % by weight of hydrogel (the cross-linked potassium polyacrylate), (3) the substrate with addition of about 0.25 % by weight of hydrogel, (4) the substrate with addition of expanded clay and perlite. The models did not have the vegetation layers in order to explore only the retention capacities of drainage layers and substrates. The aim of the first part of research was to investigate the retention capacities of green roof models after 1, 2, 6, 8 and 10 antecedent dry days. In the case of 1 and 2 antecedent dry days the best medium retention capacity had green roof model 2 (with substrate with addition of 1 % by weight of hydrogel), and the weakest medium retention capacity had green roof model 1 (without any additions). In the cases of precipitations which occurred after 6 as well as 8 and 10 antecedent dry days the best retention capacity had green roof model 3 (with addition of about 0.25 % by weight of hydrogel). The weakest retention capacity had in these cases green roof model 4 (with addition of expanded clay and perlite). The aim of the second part of research described in the paper was to investigate the retention capacities of green roof models during precipitations that occurred after long antecedent dry periods of time (34, 59 and 106 antecedent dry days). The substrates and drainage layers were air-dry directly before precipitations. The best retention capacity had in this case green roof model 3 (with the substrate with addition of about 0.25 % by weight of hydrogel). The second largest retention capacity had model 2 (with the substrate with addition of about 1 % by weight of hydrogel). The definitely weakest retention capacity had model 4 containing the substrate with addition of expanded clay and perlite. The results may indicate that the efficacy of hydrogel decreased over time probably due to its decay under the influence of solar radiation.

Open access