Removal of petroleum hydrocarbon (PHC) contamination that is hazardous and often prevalent in soils would benefit from a rapid detection technique. Visible and near-infrared spectroscopy (VIS-NIRS) has a large potential as a rapid detection technique for PHC in soils. Nevertheless, the combined influence of oil concentration, moisture content and clay content on soil reflectance spectra and the accuracy of the technique have yet received little attention. The objective of this study was to investigate the combined influence of oil concentration and moisture and clay contents on the spectral characteristics of diesel-contaminated soils and the quality of calibration models developed for polycyclic aromatic hydrocarbons (PAH) in soils using VIS-NIRS. With partial least-squares regression data from a systematic experimental design using 150 artificially contaminated soil samples, results showed that soil diffuse reflectance decreased with increasing oil concentration, clay and moisture contents. The trend was less defined in relation to moisture and clay due mainly to the interaction effects of the soil matrices as mediated by the oil. The PAH partial least squares cross-validation showed best performance with the lowest oil concentration and clay content at 20 % moisture with r ² of 0.89, root mean square error of prediction of 0.201 mg/kg and ratio of the standard error of prediction to the standard deviation of the reference data in the validation set of 2.75. Analysis of variance showed that the interaction effects of oil concentration, moisture and/or clay content significantly (p < 0.05) affected the quality of the PAH models.

The triazole fungicide epoxiconazole is extensively used to control fungi on crops and may present some potential risk from runoff on coastal ecosystems located close to agricultural areas. Phytotoxicity assessments were conducted on the marine diatom Chaetoceros calcitrans using both the active ingredient and its formulated product (Opus). The 3-day EC₅₀ using cell count was 2.31 mg/L for epoxiconazole active ingredient and 2.9 μg/L for epoxiconazole-formulated. The fungicide produced an increase of cellular volume, pigment (chlorophylls a, c, and carotenoids) content, ATP synthesis, and rates of photosynthesis and respiration. Progressive algal cell recovery from epoxiconazole effects occurred after 3 days, with the increasing cell density. Differences in cell age, light, and nutrient composition induced changes in epoxiconazole sensitivity. Since these parameters affect cellular division rates, the cellular density is an important parameter in toxicity tests.

Pressure gradients during uniform fluid flow in porous media are traditionally assumed to be linear. Thus, pressure loss across a sample of porous medium is assumed directly proportional to the thickness of the sample. In this study, measurements of pressure gradients inside coarse granular (2-18 mm particle size) porous media during steady gas flow were carried out. The results showed that pressure variation with distance in the porous media was nonlinear near the inlet (where pressure gradients were higher) but became linear at greater distances (with a lower gradient). This indicates that the pressure loss in porous media consists of two components: (1) a linear pressure gradient and (2) an initial pressure loss near the inlet. This initial pressure loss is also known from hydraulics in tubes as a minor loss and is associated with abrupt changes in the flow field such as narrowings and bends. The results further indicated that the minor loss depends on the particle size and particle size distribution in a manner similar to that of the linear pressure gradient. There is, thus, a close relation between these two components. In porous media, the minor loss is not instantaneous at the inlet point but happens over some distance starting upstream from the inlet and ending some distance downstream. © 2013 Springer Science+Business Media Dordrecht.

Two cadmium-resistant bacteria, Ralstonia sp. TAK1 and Arthrobacter sp. TM6, produced exopolymers that promoted cadmium solubilization in contaminated soil. The enhancement of cadmium uptake and accumulation in a monocot (Vetiveria nemoralis, vetiver grass) and a dicot (Ocimum gratissimum, African basil) was investigated in a greenhouse study. Compared with the uninoculated control, Ralstonia sp. TAK1 and Arthrobacter sp. TM6 increased cadmium accumulation in the roots and shoots of V. nemoralis. These cadmium-resistant bacteria increased the cadmium content of whole V. nemoralis plants similarly to ethylenediaminetetraacetic acid (EDTA) treatment alone. In contrast, only Arthrobacter sp. TM6 enhanced cadmium accumulation in the roots and shoots of O. gratissimum. The highest cadmium content of whole O. gratissimum plants was observed when the plant was treated with EDTA following treatment with Arthrobacter sp. TM6. The phytoextraction coefficient and translocation factor (TF) of bacteria-inoculated V. nemoralis were higher than those of O. gratissimum. Arthrobacter sp. TM6 increased the phytoextraction coefficients and TFs in V. nemoralis and O. gratissimum. These results indicate that Arthrobacter sp. TM6 and both tested plant species promote cadmium phytoextraction in contaminated soil.

A titanium mesostructure was synthesized, and its surface was subsequently modified by adsorbing phosphate. The modified structure was later investigated for photocatalytic activity against the organic contaminant 2,4,6-trichlorophenol with UV irradiation. This research found that the effects of calcination temperature, phosphate concentration for surface modification, amine grafting as a function, and initial pH condition contributed to the enhanced degradation rate of the chlorinated phenol. The results of this study demonstrated an increased photocatalytic degradation rate for 2,4,6-trichlorophenol under the following conditions: (1) titanium mesostructure calcined at 600 °C; (2) adsorption from a 100 mg/L as PO₄-P solution; (3) an amine-functionalized titanium mesostructure synthesized with the molar ration of 1:0.5 (titanium mesostructure: amine group); and (4) acidic condition (pH 4) to promote efficient adsorption of phosphate. This research indicates that phosphate removal and enhanced degradation of organic contaminants could be carried out simultaneously in sewage treatment.

Large quantities of pollutants such as phthalocyanine which are difficult to degrade by conventional techniques are discharged by the textile industry. Advanced oxidation processes have been shown to be capable of degrading organic compounds and removing colour from the industrial wastewater. In this research, the hydrogen peroxide (H2O2)/UV process under different operative variables has been checked using a photoreactor lab plant to analyse its behaviour in the removal of colour and chemical oxygen demand of synthetic textile wastewater with a pigment named phthalo blue 36:3 (C.I. PB15:3). Different pH and H2O2 concentrations were tested to find the better conditions for the UV/H2O2 process suitable for this kind of pollution; this was carried out as an initial study of the operative variables for the scale-up of this technology. The research has shown that with pH 7 and 5 g/L of H2O2, this process can get an organic matter removal higher than 89 % and a colour removal near 70 %. Different kinetic models of organic matter removal have been checked to analyse and predict the influence of time on the process to model similar conditions of pollution. The high correlation between empirical and theoretical data model was pseudofirst order (R 2 = 0.989 ± 0.007). © 2013 Springer Science+Business Media Dordrecht.

There are growing concerns about the increasing trends of emerging micropollutants in the environment due to their potential negative impacts on natural ecosystems and humans. This has attracted attention from both governmental and non-governmental organisations worldwide. Pharmaceuticals, personal care products, and endocrine disruptors are continuously being released consciously or unconsciously into water sources due to poor regulatory frameworks especially in the developing countries. The effects of these contaminants are poorly known. They are not easily biodegradable and have become an environmental nuisance and public health issue. This has heightened the risk of exposure to their deleterious effects in such countries where the majority of the population are still struggling to have access to good quality drinking water supplies and better sanitation. With the rising fear of short- and long-term impacts of the ever-increasing number of persistent recalcitrant organic compounds accumulating in the environment, their removal is gradually becoming an issue to the water treatment industry. Hence, there is a need to develop functional techniques for the management of water contaminated by these emerging contaminants so as to increase the availability and access to safe and good-quality drinking water. We conducted a narrative review on these emerging micropollutants and examined their various documented sources, effects, as well as recent techniques for their effective removal. This becomes necessary due to the increasing occurrence of these pollutants in the aquatic and terrestrial environment. These levels are expected to further increase in the coming years as a consequence of the ever-increasing population density which undoubtedly characterizes developing economies. Our findings show that the present reported treatment techniques in the literature such as biological oxidation/biodegradation, coagulation/flocculation, ozonation, electrodialysis, reverse osmosis, sedimentation, filtration, and activated carbon were not designed for removal of these newly identified contaminants, and as such, the techniques are not sufficient and unable to completely degrade the compounds. We therefore recommended the need for concerted efforts to develop better techniques, especially combined advanced oxidative methods to address the shortcomings of and growing challenge to current practices.

This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydrocarbon-contaminated soil. Surfactants and efficacy of oxidant activation as well as the treatability of contaminated soil were assessed. The surfactant VeruSOL-3 with a critical micelle concentration (CMC) of 5.5 g/L was selected. Based on the results, activated oxidations by sodium persulphate and hydrogen peroxide were able to effectively destroy target organic compounds in emulsion and soil. The destruction of total petroleum hydrocarbon (TPH) in emulsion was completed in 14 days and polycyclic aromatic hydrocarbons (PAHs) in excess of 96 %. Green nanoiron was much more active than other activators in emulsion. The data also indicates that oxidation using activators was much less pronounced in soil matrices. However, it is expected that given sufficient dose and treatment time, a higher destruction rate in the contaminated soil can be achieved. The study showed that the remediation of target organic contaminants (TPH, PAH) in soil by S-ISCO using activated sodium persulphate is feasible. © 2013 Springer Science+Business Media Dordrecht.

Nitrate addition stimulated sulfide oxidation by increasing the activity of nitrate-reducing sulfide-oxidizing bacteria (NR-SOB), decreasing the concentration of dissolved H2S in the water phase and, consequently, its release to the atmosphere of a pilot-scale anaerobic bioreactor. The effect of four different concentrations of nitrate (0.12, 0.24, 0.50, and 1.00 mM) was investigated for a period of 3 days in relation to sulfide concentration in two bioreactors set up at Guadalete wastewater treatment plant (Jerez de la Frontera, Spain). Physicochemical variables were measured in water and air, and the activity of bacteria implicated in the sulfur and nitrogen cycles was analyzed in the biofilms and in the water phase of the bioreactors. Biofilms were a net source of sulfide for the water and gas phases (7.22±5.3 μmol S-1) in the absence of nitrate dosing. Addition of nitrate resulted in a quick (within 3 h) decrease of sulfide both in the water and atmospheric phases. Sulfide elimination efficiency in the water phase increased with nitrate concentrations following the Michaelis-Menten kinetics (Ks=0.63 mM NO3-). The end of nitrate addition resulted in a recovery or increase of initial net sulfide production in about 3 h. Addition of nitrate increased the activity of NR-SOB and decreased the activity of sulfate-reducing bacteria. Results confirmed the role of NR-SOB on hydrogen sulfide consumption coupled with nitrate reduction and sulfate recycling, revealing Sulfurimonas denitrificans and Paracoccus denitrificans as NR-SOB of great importance in this process. © Springer Science+Business Media Dordrecht 2013.

Uptake, bioaccumulation, and assimilation of ferricyanide by three different species of willows was investigated. Intact prerooted weeping willows (Salix babylonica L.), Hankow willows (Salix matsudana Koidz), and hybrid willows (S. matsudana Koidz × alba L.) were grown hydroponically and treated with ferricyanide at 25.0 ± 0.5 °C for 144 h. Willows without leaves were also investigated as a treatment to quantify effect of transpiration on transport and assimilation of ferricyanide. Dissociation of ferricyanide to free cyanide in solution in absence of light was negligible. Phytotransport of ferricyanide was apparent. The phytoremoval rate of ferricyanide obtained varied with willow species (p < 0.05). Remarkable decreases in the removal rate were detected with the trees without leaves compared with the intact trees (p < 0.01). Due to small amounts of the applied ferricyanide recovered in plant materials, ferricyanide removed from the hydroponic solution was largely assimilated by plants. Transpiration stream concentration factor (TSCF) was also estimated using the content of iron (Fe). These information suggests that phytodegradation is a major process involved in botanical assimilation of ferricyanide through an undefined degradation pathway.