INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCE AND TECHNOLOGY (IJEST)
Year:2015 | Volume:12 | Issue:2|Papers Count:35

Biogenic iron oxides have been collected from a water stream and subsequently magnetically modified using water-based magnetic fluid. Both natural and magnetically modified materials have been characterized in detail using wavelength dispersive X-ray fluorescence spectrometry, X-ray powder diffraction, Mössbauer spectroscopy, electron microscopy and BET surface area measurements. The natural material is composed of 2-line ferrihydrite, forming hollow microtubules-sheaths of Leptothrix ochracea, and detrital components. As a result of the ferrofluid modification, maghemite nanoparticles were identified on the surface of the treated material. The active surface area of the bulk, magnetically-modified sample was 148 m2 g-1. The magnetically modified material was tested as inexpensive magnetically responsive adsorbent for the removal of selected organic xenobiotics, namely organic dyes, from aqueous solutions. The observed maximum adsorption capacities ranged between 34.3 and 97.8 mg of dye per 1 g of adsorbent.

The co-disposal of brine and fly ash has become a common practice in South African power utilities. This study focuses on the effects of the long-term fly ash-brine interaction on the chemical and mineralogical composition of fly ash and the quality of the brine solution after the interaction test. Long-term fly ash-brine interaction test was carried out by contacting fly ash and brine for a period of time varying from 1 week to 12 months under static and closed conditions. The results of the chemical composition of the brine decanted after the interaction test revealed that species such as B, Co, Cu, Pb, Mg, Mn, Zn, Cl and SO4 were removed to a certain extent from brine during the fly ash–brine interaction test while Al, Si, Ca, K, Ba, Sr, Fe, As, Cr and Mo were significantly leached out of the fly ash into the brine. The X-ray fluorescence results showed that the concentrations of Na, Mg, Cl and SO4 (as S) in the ash residues were somewhat higher than their concentrations in the fresh fly ash. Secondary mineral phases such as wairakite, charlesite, spinel and celestine which were missing in the X-ray diffraction analysis of the fresh fly ash were identified in the ash residues. This study shows that some species contained in the brine solution could be captured by the fly ash through secondary mineralization during co-disposal in a closed static environment, while many other elements could be significantly leached into the brine.

Synthetic organic compounds are hallmark of modern society. They are ubiquitous ranging from home, workplace to agriculture industry, which leads to their non-judicious dispensing into environment. Unfortunately most of them, especially polychlorinated biphenyls (PCBs), are deemed as persistent organic pollutants posing serious health risks to human. Hence, there is an alarming need of phasing out these chemicals and remediating contaminated sites in eco-friendly manner. Phytoremediation has emerged as a highly promising approach which capitalizes on plants and their associated microorganisms for removal of pollutants from targeted sites. Plant root exudations and secondary metabolites efficiently orchestrate selective recruitment of potential PCB-degrading microbial consortia within the rhizosphere and inside plant tissues. Structural analogy between organic contaminants and secondary plant metabolites (SPMEs) renders possible uptake and subsequent degradation of pollutants by microorganisms. Present review is focused on potential role of plant root exudates and SPMEs in structuring and orchestrating remediation of PCBs within rhizosphere and inside plant tissues. Also, recent developments in tools and techniques to study remediation of organic contaminants with special reference to PCBs are addressed.

This study was conducted to determine the single and combined effects of cadmium (Cd) exposure at different concentrations and durations on biological responses in Gammarus pulex. The animals were exposed to 4, 8, 16 or 32 mg l-1 of CdCl2 for 24, 48, 72 or 96 h, respectively. Cd accumulation, protein content, malondialdehyde content (MDA) and three antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were studied. The results were analyzed with two-way analysis of variance (two-way ANOVA) to assess the significance of the effects of exposure concentration and duration and their combined effects. The highest accumulation of Cd was found as 15.07 mg g-1 at 32 mg l-1 and 96-h Cd exposure. There was a significant correlation between accumulated Cd concentration and MDA and protein content and GPx activity. Although there was no significant synergistic effect of duration and concentration on Cd accumulation, a significant synergy of duration and concentration was observed in all other studied parameters. Interestingly, with the exception of GPx activity, the effect of concentration was greater than the effect of duration for all studied parameters. GPx activity showed that duration had a greater effect than concentration. Additionally, both SOD and GPx are more effective than CAT during Cd stress. The results of this study may be useful for understanding the relationship between organisms and environmental toxins.

Wash-off experiments of three Cu-based fungicides were conducted with a single raindrop simulator with known drop size and fall height. Losses were quantified as total Cu (CuT), in solution (CuL), and particulate (CuP). Cu wash-off time course was modeled for two different drop sizes using a stochastic model based on the cumulative detachment by random scattered raindrop impacts. In other set of experiments, the influence of raindrop size, fall height, and fungicide dose was analyzed statistically by means of a full factorial design. Most Cu was lost as particles sized from 0.3 to 1 mm. The stochastic model gave good estimations with two detachment performance levels. The best-fitting model parameters were as follows: the single element area covered by one impact (1.7 and 0.38 cm2 for the large and small raindrop, respectively), the average number of repeated drop impacts on one single element area that exhaust non-rainfast fungicide (4.2 ± 3.0 small drops and 2.5 ± 0.5 large drops for the high performance level, low performance level needed 30 ± 10 large drops and 40 ± 88 small drops), and the mass washed-off by a single-drop impact (from 1.27 ± 0.2 mg Cu to 3 ± 1 ng Cu per impact). Factorial design showed the dosage was the most influential factor in the three fungicide formulations. The model can help to estimate fungicide losses in field from rainfall and canopy properties. However, the particulate/soluble loss ratio cannot be predicted by the model since both the particle detachment and solubilization were not clearly related with the raindrop energy.

Hydrocarbons are widespread in the environment, but because of the massive utilization of petroleum products, they are nowadays strongly involved in environmental pollution. Bioremediation is the obliging technology for the treatment of hydrocarbon-contaminated sites. Therefore, to investigate the potential of petrochemical hydrocarbon (HC)-degrading indigenous microorganisms in wastewater samples collected from Fajr petrochemical wastewater treatment plants, a strain of Acinetobacter baumannii was isolated from this hydrocarbon-contaminated wastewater and examined for its ability to utilize hexadecane. This strain was capable to grow on n-hexadecane as the sole source of carbon and energy. The ability of the isolate to degrade n-hexadecane was assessed by growth assays and gas chromatography/mass spectrometry analysis. Using GC analysis, it was shown that the strain KSS1060 was able to degrade 62 % of n-hexadecane within 6 days, which mostly (51.6 %) occurred within the first 24 h. Identification of this hexadecane-degrader bacterium was carried out using 16S rDNA sequence analysis. Additionally, characterization of chemical composition of wastewater samples by the use of gas chromatography/mass spectrometry analysis indicated the presence of Hexanal, Benzene methanol, Indanol, 1,2-benzenedicarboxylic acid diethyl ester, diisobutyl phthalate, and Phenol,4,4′-(1-methylethylidene) in the major constituents of wastewater. In conclusion, this study can focus on more cost-efficient applications of native bacterial strains for the large-scale biodegradation of wastewater samples from petrochemical plant in industry, where it causes disturbing problems due to its harmful effects on different organisms and human beings.

A considerable economic and environmental need exists for the further development of degradable plastic polyhydroxyalkanoates (PHAs), which are produced by bacteria. However, the production cost of this bioplastic, manufactured using conventional technologies, is several times higher than that of petrochemical-based plastics. This is a major obstacle for the industrial production of PHA bioplastic for non-medical use. The aim of this review is to evaluate suitable methods for the significant reduction in bioplastic production costs. The study findings are as follows: (1) The organic fraction of municipal solid waste can be used as a raw material through acidogenic fermentation; (2) non-aseptic cultivation using mixed bacterial culture can significantly reduce the production cost; (3) biotechnology of bacterial cultivation should ensure selection of PHA-accumulating strains; (4) applications of PHA-containing material in both construction industry and agriculture do not require expensive extraction of PHAs from bacterial biomass. The implementation of the above findings in the current manufacturing process of PHA-containing bioplastic would significantly reduce production costs, thereby rendering PHA-containing bioplastic an economically viable and environmentally friendly alternative to petrochemical-based plastics.

Tannery-affected surface soils from 72 sampling sites from industrial area of Sialkot district, Pakistan, were collected and analyzed for nine physicochemical parameters, nine heavy metals, and four macro-nutrients. Most of the soils were poor in organic matter (0.11–2.98 %), basic in nature with pH (7.1-10.6) and electrical conductivity (1.2-17.9 mS/cm). Mean concentration of total dissolved solids, Cl1-, alkalinity, NO 3 1 -N, salinity, and PO4 3- was 3,093 mg/L, 6,587, 3,929, 301.3, 10.3, and 1.7 mg/kg. The results showed that concentration of macro-nutrients was in the order: Na>Mg>K>Ca whereas heavy metals followed the order: Cr>Fe>Ni>Mn>Cu>Zn>Co>Pb>Cd. Factor analysis based on principal component analysis, cluster analysis, and correlation analysis identified contribution of metals from tannery effluents, agrochemicals, automobiles exhaust, and natural weathering processes. Tannery-affected soils were enriched with Cd followed by Cr, Pb, Ni, Cu, Co, Zn, and Mn. Geo-accumulation index (I geo) classified the soil samples in unpolluted to moderately polluted categories. Metal pollution index provided better estimation of heavy metal pollution as compared to pollution load index. Ecological risk index showed high potential ecological risk associated with Cd and Cr with mean concentrations above respective average shale/background values. The results are useful for heavy metals source identification, enrichment, risk assessment, and management of tannery-affected soils and can contribute to monitoring programs at regional levels.

Biosorption characteristics of Pb (II) ions from aqueous solution were studied using some residues of solvent-extracted Otostegia persica known as goldar residue biomass. The effects of contact time (0–120 min), the initial pH 3–8, biomass dosage (0.53-2.6 g/L) and the initial lead concentration (5-25 mg/L) on biosorption were investigated. The maximum adsorption capacity of 17.3 mg/g at pH 5.5, the initial lead concentration of 25 mg/L and goldar residue biomass dosage of 1.06 g/L were obtained. The results of equilibrium adsorption were studied through different isotherm models of Langmuir, Freundlich, Temkin, Halsey, Scachard and Dubinin-Radushkevich. Different kinetic models including pseudo-first-order, pseudo-second-order and intraparticle diffusion were applied. The pseudo-second order described the adsorption kinetics data properly. Thermodynamic investigation at temperatures ranging from 25 to 45oC showed a reduction in both the possibility of adsorption and randomness at the solid–solution interface of goldar residue. Fourier transforms infrared analysis confirmed the presence of several functional groups on the surface of the goldarresidue biomass during lead adsorption. O. persica residue biomass showed good properties to use as a new biosorbent for removal of low concentrations of lead ions from water.

The kinetics and thermodynamics of the biosorption of textile dye Congo Red on anaerobic activated sulfidogenic sludge were examined. The influence of different adsorption parameters such as pH, temperature, contact time and initial dye concentrations on the biosorption capacity was also investigated. The sulfidogenic sludge showed a maximum biosorption density of 238.90 mg dye/g cell for Congo Red at an initial dye concentration of 1,000 mg/L, pH 3.5 and 22oC, which is higher than that of many other adsorbents reported in the literature. The biosorption processes obeyed the Langmuir isotherm and exhibited pseudo-second-order rate kinetics. The thermodynamic parameters indicated the spontaneous and exothermic nature of Congo Red biosorption. The Fourier transform infrared spectra revealed the dye interaction with the biomass. Scanning electron microscopy showed significant changes in the surface morphology of the sludge after dye biosorption. These results showed that sulfidogenic sludge biomass is an attractive alternative low-cost biosorbent for the removal of the dye from aqueous media.

Based on the recently discovered peroxidase-like activity, cupric oxide nanoparticles with diameters about 6 nm were synthesized and used to remove phenol from aqueous solution. As a kind of peroxidase mimetic substance, cupric oxide nanoparticles can be used as a promising catalyst for the total oxidation of phenol in aqueous solutions by peroxidation, which therefore avoids the need of secondary treatments. The mechanism study suggested that cupric oxide nanoparticles could catalyze hydrogen peroxide to form hydroxyl free radicals, which were mainly responsible for the removal of phenol. The catalytic conditions for the phenol degradation were extensively optimized among a range of pH as well as initial concentration of catalyst, H2O2 and phenol. High degradation efficiency of phenol can be achieved in relatively wide pH range from 3 to 7. Under optimized conditions, phenol (0.25 g/l) can be eliminated completely in 35 min. It can be potentially applied in treating the industrial wastewaters.

Cyanide is a simple nitrogenous compound that arises from both anthropogenic and natural sources. Plants vary considerably in their physiological and biochemical responses to different species of exogenous cyanides from reduced growth to inhibition on enzymatic activities. Also, great differences in uptake, assimilation and toxicity between free cyanide and iron cyanide have been observed. Unlike botanical uptake of free cyanide chiefly achieved by simple diffusion, iron cyanides have long been considered membrane impermeable and a protein-mediated uptake mode has been proposed. Biological fate of cyanides in plant materials is highly dependent on speciation of cyanides present. Natural development of degradation of free cyanide in plants is very obvious, where the b-cyanoalanine pathway has been widely distributed in higher plants and the production of asparagine and aspartate associated with cyanide assimilation is suggestive. Because phyto-dissociation of iron cyanides into free cyanide in plant materials is not a mandatory process involved in phyto-assimilation, plants probably metabolized them through an undiscovered degradation pathway rather than the b -cyanoalanine pathway. Available information shows phyto-assimilation of endogenous cyanide into nitrogen metabolism; however, additional efforts to fully elucidate presence of essential enzymes involved and their proteomic or DNA expression quantitatively are needed to prove and clarify phyto-benefits of assimilation of exogenous cyanide in plant nutrition.

The influent type of organic matter (dissolved or particulate) on the characteristics of two subsurface wastewater infiltration systems (SWISs) was investigated. One of the SWISs was fed with dissolved organic matter (glucose, assumed to be readily biodegradable) and the other with particulate organic matter (starch, assumed to be slowly biodegradable). Results showed that both biofilm growth and particle accumulation in substrate could reduce the effective porosity and infiltration rate of SWIS, especially for the high organic matter concentration wastewater. The reduction in effective porosity and infiltration rate was primarily caused by organic particle accumulation. The contribution of the accumulated organic particle to the process of clogging was greater than that of biofilm growth and the clogging mainly occurred in the upper layer in starch-fed systems. The SWISs fed with glucose were not clogged till the end of experiments. The hydraulic retention time (HRT) increased with time in start-up period and was almost invariable after mature in glucose-fed systems; in starch-fed systems, clogging of substrate prolonged the HRT. The two identical experimental SWISs were almost equal efficiencies for the removal of chemical oxygen demand (COD). The removal efficiencies of COD were not influenced by clogging under the experimental conditions. Ammonia N removal efficiency was higher in glucose-fed systems than that in starch-fed systems.

The current study deals with evaluation of biosorption feasibility for removal of Cu (II) and Zn (II) by hybrid immobilized biosorbent of Pleurotus sajor-caju and Jasmine sambac. Batch adsorption experiments were carried out to assess the effect of pH, initial metal concentration, biomass dose, temperature and time. The biosorption efficiency of Cu (II) and Zn (II) ions for hybrid immobilized biosorbent increases with rising pH values. The hybrid immobilized biosorbent illustrated the highest biosorption capability at pH 5 for Cu (II), 6 for Zn (II), at 0.05 g/100 mL dose and 100 mg/L initial metal concentration of both ions. Uptake kinetics followed the pseudo-second-order model and equilibrium was described by Langmuir and Freundlich isotherms. Adsorption ratios of Cu (II) and Zn (II) were best fitted to Langmuir isotherm. The best temperature for ion uptake was found to be 30oC.

The combination of liquid chromatography coupled to mass spectrometry (LC–MS) and acute toxicity studies with Daphnia magna was used to elucidate the water stability of the cytostatic compounds, mitoxantrone and chlorambucil, and their transformation products (TPs). Both compounds were rapidly degraded in water with the subsequent formation of bioactive TPs. Mitoxantrone suffered a rapid change in its conformation with the formation of four toxic TPs, which were unaltered and stable in water along the 2-day studied period. LC-MS analyses were allowed to identify the conformational changes of mitoxantrone that included the loss of the two amino alcohols (N-ethylethanolamina) [C4H10NO]+, the loss of N-ethylethanolamina [C4H10NO]+ and N-methylethanolamina [C3H8NO]+, the loss of CH2OH from the original molecule and the formation of mitoxantrone dicarboxilic acid. Chlorambucil was also rapidly degraded in water loosing a hydroxyl group and forming a bioactive TP that further degraded within the following 12 h. The degradation of chlorambucil was also related to an exponential loss of toxic activity towards D. magna survival. The present results indicate that LC–MS methods should target TPs since field concentrations of these compounds measured in water may not reflect their toxicity.

An environment friendly arsenic removal technique from contaminated soil with high iron content has been studied. A natural surfactant extracted from soapnut fruit, phosphate solution and their mixture was used separately as extractants. The mixture was most effective in desorbing arsenic, attaining above 70 % efficiency in the pH range of 4-5. Desorption kinetics followed Elovich model. Micellar solubilization by soapnut and arsenic exchange mechanism by phosphate are the probable mechanisms behind arsenic desorption. Sequential extraction reveals that the mixed soapnut–phosphate system is effective in desorbing arsenic associated with amphoteric–Fe-oxide forms. No chemical change to the wash solutions was observed by Fourier transform-infrared spectra. Soil:solution ratio, surfactant and phosphate concentrations were found to affect the arsenic desorption process. Addition of phosphate boosted the performance of soapnut solution considerably. Response surface methodology approach predicted up to 80 % desorption of arsenic from soil when treated with a mixture of  »1.5 % soapnut, »100 mM phosphate at a soil:solution ratio of 1:30.

Natural radioactivity is responsible for most of the total radiation dose received by human population. Geological materials used in building industry usually become contaminated with naturally occurring radioactive materials. They are used as mixtures in building industry (kaolin, zircon, frit, feldspar) or mechanically processed and used for covering floors and walls of the rooms (granite). In this paper, activity concentrations of 226Ra, 232Th and 40K in 6 kaolin, 11 zircon, 18 granite, 3 marble, 6 sand, 4 perlite, 4 feldspar, 5 korund and 1 frit samples imported in Serbia were determined by gamma-ray spectrometry. Activity concentration index, dose rate and annual effective dose were calculated for each of the investigated samples. Measurement of an external gamma dose rate by using a commonly available radiation survey meter can give some indication of the need for further investigations. The absorbed dose rate and annual effective doses for workers in the ceramic industry “Keramika Kanjiza Plus” in Serbia working with granite are determined.

Heteropneustes fossilis were subjected to 41.89 mg L-1 of azadirachtin for short-term exposure (96 h) and 10.47 mg L-1 of azadirachtin for long-term exposure (28 days). The fish were killed on 24, 48, 72 and 96 h in short-term and 7, 14, 21 and 28 days in long-term experiment. Corpuscles of Stannius (CS) were fixed on these time intervals. CS remain unchanged till 72 h in short-term azadirachtin exposure. Accumulation of granules has been noticed in the aldehyde fuchsin (AF)-positive cells at 96 h. The nuclear volume of these cells remains unchanged. The AF-negative cells of CS of azadirachtin-exposed fish exhibit a slight increase in their nuclear volume after 96 h. In long-term exposure, the CS remain unchanged up to day 14. Increased granulation in the AF-positive cells has been noticed following 21-day exposure. Moreover, the nuclear volumes of these cells show a significant decrease. Heavy accumulation of AF-positive granules and few degenerating cells are also noticed at 28 day in azadirachtin-exposed H. fossilis.

The adsorption of As (III) from aqueous solutions using naturally occurring and modified Algerian montmorillonites has been investigated as a function of contact time, pH, and temperature. Kinetic studies reveal that uptake of As (III) ions is rapid within the first 3 h, and it slows down thereafter. Equilibrium studies show that As (III) shows the highest affinity toward acidic montmorillonite even at very low concentration of arsenic. The kinetics of As (III) adsorption on all montmorillonites used is well described by a pseudo-second-order chemical reaction model, which indicates that the adsorption process of these species is likely to be chemisorption. Adsorption isotherms of As (III) fitted the Langmuir and Freundlich isotherm models well. The adsorption of As (III) is pH-dependent obtaining an optimal adsorption at pH 5. From the thermodynamic parameters, it is concluded that the process is exothermic, spontaneous, and favorable. The results suggest that M1, M2, and acidic-M2 could be used as low-cost and effective filtering materials for removal of arsenic from water.

The performance of 1,1,1,2-tetrafluoroethane or HFC-134a decomposition and the formation of byproducts in a dielectric barrier discharge plasma reactor were studied with different packing systems such as a-Al2O3 (porous and nonporous), g-Al2O3 (porous) and ZrO2 (nonporous). Experimental variables such as reactor temperature, initial HFC-134a concentration and oxygen levels were chosen for the performance analysis. Among the packing systems, the porous g-Al2O3and a-Al2O3 decomposed HFC-134a much more effectively than the nonporous a-Al2O3 and ZrO2. The combination of the plasma with the porous g-Al2O3 was found to cover a wide range of initial concentration. The decomposition efficiency tended to increase with the addition of oxygen up to 2 %, but further increase in the oxygen led to a decrease. As well as carbon oxides (CO2 and CO), significant amounts of unwanted byproducts such as COF2 and CF4 were also identified in the effluent gas with the nonporous a-Al2O3 and ZrO2. On the contrary, with the porous g-Al2O3 and a-Al2O3, such unwanted byproducts were considerably suppressed, enhancing the formation of CO2 and CO.

In view of the significant hydrological and ecological role of wetlands, an analysis was made on the impact of land use and land cover dynamics on the spatial status of Zhalong wetland, a Ramsar site located downstream of Wuyuer River Basin in Northeast China. The impact assessment analyzed multi-temporal changes in the upstream land use/land cover characteristics of the wetland watershed using remote sensing data of Landsat MSS/TM. The multi-temporal land use/land cover statistics revealed that significant changes have taken place in the Wuyuer River Basin. In response to these upstream land use/cover changes, the marsh landscape in Zhalong wetland has showed changes in spatial extension, landscape pattern, and water quality characteristics. The major impacts have resulted from construction of a reservoir and water diversion engineering that has altered the wetland hydrological conditions and reduced the spatial distribution of the marsh landscape. In addition, inputs of agricultural nutrients, and industrial and human wastes from the upper catchments have resulted in increased signs of eutrophication. This study suggests that effective wetland hydrological restoration measures are needed to avoid further deterioration of this internationally important ecosystem.

On-site sanitation provisions in urban slums rarely prioritise grey water management, yet it forms the largest fraction of wastewater. This study was carried out to characterise grey water and quantify its pollutant loads in Bwaise III (Uganda) and to provide data for grey water management in urban slums of developing countries. Samples were collected for analysis from ten representative households as well as from four tertiary drains and the main drainage channel for 7 months in two dry seasons. Grey water production was found to comprise 85 % of the domestic water consumption. The chemical oxygen demand (COD) concentration in the grey water generated by laundry, in the kitchen and in the bathroom was 9,225 ± 1,200 mg L-1, 71,250 ± 1,011 mg L-1 and 4,675 ± 750 mg L-1, while the BOD5 (biochemical oxygen demand) to COD ratio was 0.24 ± 0.05, 0.33 ± 0.08 and 0.31 ± 0.07, respectively. The maximum concentration of Escherichia coli and total coliforms was 2.05 × 107 cfu (100 mL) -1 and 1.75 × 108 cfu (100 mL) -1, respectively, in grey water from the bathroom, while that of Salmonella spp. was 7.32 × 106 cfu (100 mL) -1 from laundry. Analysis of variance (ANOVA) showed a significant difference in the concentration of COD, total suspended solids (TSS), total organic carbon (TOC), dissolved organic carbon (DOC), total phosphorus (TP), sodium adsorption ratio (SAR), oil and grease, and Salmonella spp. in grey water from laundry, bathroom and kitchen (p < 0.05). The high loads of COD (>500 kg day-1), TSS (>200 kg day-1), nutrients (8.3 kg TKN day-1and 1.4 kg TP day-1) and microorganisms (106 to 109cfu c-1 day-1) originating from grey water in Bwaise III show that grey water poses a threat to the environment and a risk to human health in urban slums. Therefore, there is a need to prioritise grey water treatment in urban slums of developing countries to achieve adequate sanitation.

In a municipal solid waste (MSW) compost field, Kochia scoparia, an easy-to-grow weed plant, gradually invaded the experiment site and became the dominant species after 4 years’ succession. Ethylenediaminetetraacetic acid (EDTA) solution at five rates 0, 25, 50 mmol L-1, 25 mmol L-1 + 1 g L-1 ammonium sulfate (NH4)2SO4, and 50 mmol L-1 + 1 g L-1 (NH4)2SO4 was added to the tested plant root medium. The effects of EDTA and (NH4)2SO4 on Pb and Cr distribution in K.scoparia were investigated. Results suggested that plant biomass increased greatly with height, showing an “inversion pyramid” pattern in spatial structure. At the level of 50 mmol L-1EDTA, single additions and combined additions with (NH4)2SO4 increased Pb and Cr concentrations in plant shoots at different heights. Lead and Cr uptakes increased toward the top of the shoot. Combined application of 50 mmol L-1 EDTA and (NH4)2SO4 increased Pb uptakes by 21.6, 19.2, 111.3, 124.3, and 154.0 % in 0-30, 30-60, 60-90, 90-120, and over 120 cm spatial shoots, respectively, as compared to those of controls. The increment for Cr uptake was 244.5, 281.7, 100.0, 77.2, and 187.4 %. The relationship between Pb and Cr concentrations in plant shoots and spatial height was found to be positively linear and statistically significant at 1 % level at 50 mmol L-1 EDTA alone and 25 mmol L-1 EDTA together with (NH4)2SO4. Results presented here indicated that K. scoparia had potential in removal of Pb and Cr from MSW compost with the combined application of EDTA and (NH4)2SO4.

The aim of the study was to investigate the degradation kinetics of tetracycline antibiotic by nanosized titanium dioxide under ultraviolet irradiation. Enhancement of photocatalysis by addition of Hydrogen peroxide was also evaluated. Various experimental parameters such as initial tetracycline concentrations, initial titanium dioxide concentration, initial pH, reaction times, initial Hydrogen peroxide concentrations, as well as water matrix using ultrapure water, drinking water and secondary effluent were investigated. The initial rate of photocatalytic degradation of tetracycline well fitted the Langmuir–Hinshelwood kinetic model (R 2 = 0.9926) with a reaction rate constant of 1.4 mg/L min. The degradation rate depended on initial tetracycline concentration and initial pH. The degradation rate also increased with higher titanium dioxide density and reached a plateau at titanium dioxide concentration of 1.0 g/L. The tetracycline degradation rate was higher in drinking water compared to ultrapure water. The addition of Hydrogen peroxide to titanium dioxide suspension significantly enhanced the tetracycline degradation rate and substantially reduced the time required to degrade 100 % of tetracycline. Changes of chemical oxygen demand values during photolysis indicated that tetracycline transformed into intermediate products without complete mineralization. The ultraviolet visible spectra obtained before and after ultraviolet irradiation in the presence of titanium dioxide can indicate the formation of 4a,12a-anhydro-4-oxo-4- dimethylaminotetracycline.

Aliphatics (n-alkanes) and polycyclic aromatic hydrocarbons (PAHs) were measured in surface sediments collected from 12 sampling points (P1-P12) of sewage discharge to the sea from the wastewater treatment plant of Cortiou (France). Total n-alkanes and PAHs concentrations ranged from 34 to 2,155 and 696 to 10,700 μg kg-1, respectively. Some specific hydrocarbon indexes suggested that terrestrial biogenic inputs are predominant compared to marine sources and that pyrolytic sources derived from wood and biomass combustion contribute to PAHs in the surface sediments. Total linear alkyl benzenes in Cortiou sediments ranged from 42.9 to 502.3 mg kg-1. Low internal and external (I/E) isomers ratio (P0) suggests that inadequately treated sewage is discharged into the marine environment while some environmental processes might change I/E ratios during transport seaward (P1-P12). The high contaminant levels followed by the cumulative concentration of several compounds may lead to elevated toxicity levels in the sediments.

Metallic iron is present in the waste left when granite blocks are cut. Thus, the purpose of this study was to characterize this waste using chemical and particle size analyses. To achieve this, X-ray diffraction and scanning electron microscopy coupled with electron back-scattered diffraction were used. To find the method with the best metallic iron recovery from the waste of ornamental rock, three distinct methods were examined: magnetic separation, table concentration and cyclone processing. The first method involved three steps: (1) use of a wet high-intensity magnetic separator, where only the equipment’s remaining magnetic field was present; (2) the material from the first step was then submitted to separation again, this time using a magnet for rare earth particles; and (3) this material after two separation processes was finally submitted to ferromagnetic separation. The second method used a concentration table set at various inclinations, oscillation frequencies and wash flow rates. Meanwhile, for the third method, the cyclone tests, only the water pressure was varied. After each test, a chemical analysis was performed to determine the metallic iron present in each sample. The tests revealed that magnetic separation presents the best results. Using this technique, a ferrous concentrate with 93 % metallic iron content and a granite concentrate with only 0.6 % metallic iron were obtained. On the other hand, in the table concentrator tests, the ferrous concentrate only had a metallic concentration of 13.6 %. In separation by the cyclone processing, the product barely contained metallic iron (7.2 % maximum).

Uncertainty is inherent in watershed modeling but it is not fully acknowledged in model applications. This review focuses on uncertainty issues related to the Soil and Water Assessment Tool (SWAT) model, which is one of the most useful tools for simulating nonpoint source (NPS) pollution processes. We considered numerous studies that addressed three types of uncertainty in detail, i.e., the model inputs, parameters, and model structure. It has been shown that rainfall data, in terms of the spatial rainfall variability and the accuracy of the measured data, play a key role in the accuracy of the SWAT model. Geographic information system inputs, including the digital elevation model, land use map, and soil type map, have also been identified as key sources of input errors. With respect to the parameter uncertainty and model structural uncertainty, it is anticipated that the complex, nonlinear structure, and numerous parameters included in the SWAT model may lead to a failure to identify parameters, as well as equifinality phenomenon. We also compared some widely used uncertainty analysis methods, such as the generalized likelihood uncertainty estimation and first-order error analysis, to provide reliable guidance for the application of the SWAT model. This study benefits a wide range of researchers, who are concerned with uncertainty issues in NPS pollution modeling, and it provides insights into the application of watershed models in the development of watershed programs.

An attempt to synthesize an active photocatalyst for 2-methyl-4-chlorophenoxyacetic acid removal has been accomplished. Black light (main emission wavelength at 365 nm) photocatalytic experiments with bare and N-doped titania have been carried out, and the results compared to those obtained in the presence of titania Degussa P-25. Doping percentage and calcination temperature influences have been investigated in photocatalytic runs using pure and commercial 2-methyl-4-chlorophenoxyacetic acid. In no case, the results obtained with synthesized titania improved the activity of P-25. Some kinetic tests allowed for the proposal of a pseudoempirical reaction mechanism capable of acceptably simulating the process in the presence of P-25. From the proposed mechanism, the roles played by hydroxyl, peroxyl and organic radicals have been suggested.

The recovery of phosphorus from wastewater has gathered strength due to its acceptance as a sustainable method for solving wastewater treatment plant struvite problems and the low global reserves of phosphorus ore. Although the chemistry and successful operation of phosphorus recovery plants are well documented, there still exists opportunity to reduce and optimize the use of external resources, such as magnesium, that is required for the nutrient recovery. One of the primary operational costs arises from the need for external magnesium addition, and therefore, the proper (and timely) detection of the element is necessary. In this study, methods were tested which could provide information, on-site, on the rate of application of the element and its concentration in the various water matrices. A method was developed that utilizes the combined use of pH and conductivity to determine the amount of external magnesium that needs to be added to a water sample. The amount required was determined by locating a transition point in the pH-conductivity-external magnesium added graph and the phosphate concentration in the water. For each mole of phosphorus removed, the molar ratio of Mg:P was 1.3-2.0 at the transition point. The magnesium concentration in the water matrix was also determined by the hardness test method; this method was found to be suitable for quick, on-site testing.

This study investigated health risk reduction in a drinking water treatment plant of Nanjing City (China) based on chemical detection of 22 semi-volatile organic compounds (SVOCs) and 24 metallic elements in source water and drinking water during 2009-2011. Chemical analysis showed that 15 SVOCs and 9 metals were present in the water. Health risk assessment revealed that hazard quotient of each pollutant and hazard index (HI) of all the detectable pollutants were below 1.00, indicating that the chemicals posed negligible non-carcinogenic risk to local residents. Benzo (a) pyrene may induce carcinogenic risk since its risk index via both oral and dermal exposure exceeded the safety level (1.00E-6), but other SVOCs induced no carcinogenic risk. Total HI of the SVOCs was 1.08E-3 for the source water and 1.56E-3 for the drinking water, suggesting that the used conventional treatment processes (coagulation/sedimentation, sand filtration and chlorine disinfection) cannot effectively reduce the non-carcinogenic risk. The source water had higher carcinogenic risk than the drinking water, but risk index of the drinking water still exceeded 1.00E-6. This study might serve as a basis for health risk assessment of drinking water and also as a benchmark for the authorities to reduce health risk arising from trace-level hazardous pollutants.

The present study provides an electrocoagulation process for the removal of lead from water using magnesium and galvanized iron as anode and cathode, respectively. The various operating parameters such as the effect of initial pH, current density, electrode configuration, inter-electrode distance, co-existing ions and temperature on the removal efficiency of lead were studied. The results showed that the maximum removal efficiency of 99.3 % at a pH of 7.0 was achieved at a current density 0.8 A/dm2 with an energy consumption of 0.72 kWh/m3. The experimental data were fitted with several adsorption isotherm models to describe the electrocoagulation process. The adsorption of lead preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. In addition, the adsorption kinetic studies showed that the electrocoagulation process was best described using the second-order kinetic model at various current densities. Thermodynamic parameters, including the Gibbs free energy, enthalpy and entropy, indicated that the lead adsorption of water on magnesium hydroxides was feasible, spontaneous and endothermic.

Membrane bioreactors (MBRs) are rapidly becoming the technology of choice over conventional activated sludge treatment systems due to their smaller footprint, reduced sludge production, rapid start-up of biological processes, complete removal of suspended solids and better effluent quality. The retention of sufficient amount of slow-growing nitrifiers makes it feasible for the MBRs to achieve strong tolerance against the shock loads with stable and highly efficient nitrogen removal. Various studies have focused on the ecophysiology of nitrifiers in MBRs as well as their distinctive operational parameters as well as their impact on the selection and activity of nitrifying community. Several techniques have been employed over the years to understand the nitrifying community and their interaction within the MBR system, which led to its modification from the initial design. This review focuses on the identification of optimal operational and environmental conditions for efficient nitrification in MBRs. The advantages and limitations of different techniques employed for investigating the nitrifying communities in MBRs are also emphasized.

Flow unsteadiness in flood events has a significant effect on the structure of the flow field and motion of sediment particles, thereby affecting dispersion of pollutants and river ecology. The aim of the present article was to evaluate state-of-the-art research efforts concerning flow characteristics and sediment transport in unsteady flow condition. The paper is organized in four sections: The first section deals with the unsteady parameters which affect sediment transport. In the second section, the flow characteristics in unsteady open channel flow are presented. Different studies showed that the flow characteristics which affect sediment transport including velocity distribution or shear stress during passage of a hydrograph differ from steady flow condition. In addition, measurements during passage of a hydrograph show that turbulence intensity is generally larger in the rising limb of the hydrograph rather than in the falling limb. This causes the peak of sediment load and pollutants occur during the rising limb of the storm hydrograph. The third and forth sections deal with bed load and suspended load in unsteady flow condition, respectively. Studies show that the methods which are based on steady flow conditions generally underestimate the sediment transport rates in unsteady flows. The larger the unsteadiness, the bigger is the difference. Finally, with considering different findings from previous studies, suggestions are presented for further research.

The monthly total amount of dust fall, as well as its chemical and physical characteristics, was systematically investigated in Shuwaikh city, Kuwait. Dust samples were collected on a monthly basis for the entire year of 2009 and analyzed in the laboratory for water-soluble and water-insoluble matter. Water-insoluble matter represented the major portion of the total annual dust. ANOVAs showed significant temporal variation in the concentration of dust fall over the months (p < 0.05). Higher dust deposits were encountered between June and August and ranged from 76.4 to 97.6 ± 2.5 (SD) ton km-2 month-1, where dusty winds and low humidity are a common attribute in such arid areas. The main three soluble matter species measured are nitrate, sulfate, and chloride, and sulfate was found to be the most abundant inorganic species, ranging from 0.72 ± 0.13 to 4.1 ± 0.3 ton km-2 month-1. Major insoluble matter species measured are ash, silica, combustible, and tarry. Ash, silica, and combustible account for 63, 19, and 17.8 % of total insoluble dust, and 58.4, 17.7, and 16.6 % of total dust, respectively. Particle size distribution was also investigated, and results showed that dust particles >7 mm were the highest concentration of falling dust. Metrological conditions were found to play a vital role in temporal variations in falling dust.

The atmospheric impact of stack emissions from a power plant (tri-generator and boilers) that will be installed in an urban area in the central Po valley (Northern Italy), characterized by calm wind events, is studied and compared with the impact of the existing plant (conventional boilers). Both the plants are supplied by methane gas. The atmospheric dispersion of NOx emitted is simulated, both in the current and future scenario, by the software package ARIA INDUSTRY. The NOx emission rates are set equal to the regulatory emission limits for existing and future boilers, while the tri-generation system emission rates are set equal to the emission limits certified by the system manufacturer. The simulation periods focus over the 2010 winter season. The simulation estimates the impact of NOx emissions on air quality (vertical concentration profiles and concentration maps at the ground) in the urban area close to the plant. The future power plant impact on air quality results lower than the impact of the existing plant, even if the yearly total mass of pollutants emitted in atmosphere from the new power plant is higher than from the existing plant. The emissions of conventional boilers result the main responsible of the air pollution at the ground in the future scenario.