Coal mine methane is a significant greenhouse gas source as well as a potential lost energy resource if not effectively used. In recent years, mine ventilation air (MVA) capture and use has become a key element of research and development due to comparatively larger methane emissions by MVA than other coal mine sources. Technologies have been evaluated to treat the low methane concentrations in MVA such as thermal-based technologies or processing by biofiltration. This review initially considers the techniques available for treating the low methane concentrations encountered in MVA, after which it focuses on developments in biofiltration systems. Biofiltration represents a simple, energy-efficient, and cheap alternative to oxidize methane from MVA. Major factors influencing biofilter performance along with knowledge gaps in relation to its application to MVA are identified and discussed.

Some Pseudomonas fluorescens strains, consistently isolated from the rhizosphere of wild plants grown in a soil that was highly polluted with illegal waste of smelter residues, were utilised for Mirabilis jalapa seed bioinoculation to verify their effects on seed germination and on promoting a higher heavy metal accumulation in the plant rhizosphere and/or uptake in the leaves. The high content of heavy metals in the soil induced a decrease in either the leaf dry weight or photosynthetic pigment concentration during all vegetative phase of M. jalapa. Bioinoculation with P. fluorescens strains significantly increased the germination of seeds and the root length in the contaminated soil. In some bacterial strain/seed combination, bioinoculation significantly increased the accumulation of heavy metals in M. jalapa rhizosphere. For Cd, the concentration of this metal in the rhizospheres of bioinoculated plants ranged from 270 to 910 μg g-1 of dry weight compared with 200 μg g-1 of dry weight for the non-coated plants. Two P. fluorescens strains, AA27 and MO49, which were isolated from Artemisia annua and Melilotus officinalis, respectively, induced a significantly higher rhizosphere availability also for Cr, Cu, Ni and Zn. However, despite the relevant accumulation of the heavy metals in the plant rhizosphere, generally the metal uptake into the leaves was rather low. Both analysis of variance and principal component analysis confirmed this finding. However, one P. fluorescens strain, CD1, which was isolated from the multi-metal accumulator Cynodon dactylon, significantly promoted the M. jalapa leaf uptake for Cr, Cu and Zn. The plant metal uptake assessment, confirmed the per se capability of M. jalapa to effectively uptake Cd (30 %) and Cu (12.72 %) from the rhizosphere to the leaves, whereas the uptake for the other metals was low: Ni (2.66 %), Zn (2.46 %), Cr (1.75 %), Pb (0.73 %). © 2013 Springer Science+Business Media Dordrecht.

There are significant concerns about the impact of heavy metal contamination in soils as a consequence of urbanisation and industrialisation in developing countries. Routine chemical analysis of soils is used to measure the total concentration of metals from point source or diffuse activities, but this fails to put in context the bioavailability of the analyte or the potential toxicity of multiple contaminants. Bacterial biosensors provide a useful tool for assessing the toxicity of the bioavailable fraction of heavy metals in soils and for complementing chemical analysis. There are few examples of genuine environmental applications of biosensors for pollutant diagnosis. This study applied constitutively marked biosensors (which were comprehensively characterised) to soils collected from across Northern China (60,000 km²). The biosensors were responsive to soils impacted by As, Cd, Cr, Cu, Hg, Pb, and Zn when compared to ‘uncontaminated controls’. The response of the biosensor correlated with individual (or groups of) metals related to their concentration and source. The geo-accumulation index (I gₑₒ) assisted in explaining the biosensor response. The constitutively marked biosensors offered a focussed understanding of analyte bioavailability and placed in a relevant context the elemental analysis. When matrix-matched control samples can be collected, then such a biosensor procedure (as adopted here) is applicable to contrasting soils exposed to a wide range of contaminants. Biosensor applications complemented routine soil chemical analysis for this regional-scale study.

Two Co oxide catalysts supported on natural zeolites from Indonesia (INZ) and Australia (ANZ) were prepared and used to activate peroxymonosulphate for degradation of aqueous phenol. The two catalysts were characterized by several techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS) and N2 adsorption. It was found that Co/INZ and Co/ANZ are effective in activation of peroxymonosulphate to produce sulphate radicals for phenol degradation. Co/INZ and Co/ANZ could remove phenol up to 100 and 70 %, respectively, at the conditions of 25 ppm phenol (500 mL), 0.2 g catalyst, 1 g oxone and 25 C. Several parameters such as amount of catalyst loading, phenol concentration, oxidant concentration and temperature were found to be the key factors influencing phenol degradation. A pseudo first order would fit to phenol degradation kinetics, and the activation energies on Co/INZ and Co/ANZ were obtained as 52.4 and 61.3 kJ/mol, respectively. © 2013 Springer Science+Business Media Dordrecht.

In this study, residues of passion fruit skin were examined as biosorbent materials, evaluating their capacity to adsorb lead(II) ions in in natura skin (SK-N) and two modified skins, with NaOH (SK-S) and with NaOH and citric acid (SK-SCA). The biomass characterization was done through Fourier transform infrared spectroscopy which confirmed the chemical modification by a peak at 1,730 cm⁻¹. Also, scanning electron microscopy analyses were done, where the increase of residue roughness was observed after the modification. And finally, the values of point of zero charge were determined and were lower than 5.5 for all residues. In the experiments of adsorption in function of pH, it was verified that after pH 4, the adsorbed amount was practically constant. Regarding the necessary time to reach equilibrium, the value that was found was approximately 170 min, and kinetics followed the behavior described by the pseudo-second-order equation. The maximum adsorption capacity was 204 mg g⁻¹ for the SK-SCA biomass. The residues followed Langmuir adsorption model. Through thermodynamic parameters, it was verified that adsorption occurs spontaneously due to the negative values of Gibbs' energy. Moreover, desorption studies showed that adsorbed ions may be recovered in two cycles. Thus, due to the high adsorption capacity of lead ions, passion fruit skin can be utilized in filters to retain this metal in the future.

Adsorption of fluoroquinolone antibiotics using sludge-derived biochar made of various wastewater sludges was investigated. The sludge-derived biochar had relatively large Brunauer–Emmet–Teller specific surface areas that were beyond 110.0 m² g⁻¹ except the biochar made from the sludge collected from traditional sludge drying bed. The mesopore capacity was more than 57 % of the total pore capacity of all sludge-derived biochar except that made from the sludge dried through traditional sludge drying bed technique. High adsorption capacity of sludge-derived biochar was observed with a highest adsorption capacity of 19.80 ± 0.40 mg g⁻¹. High correlation between the adsorption capacity of sludge-derived biochar and the volatile content in the sludge source was observed. The Freundlich model (r ² values were in the range of 0.961–0.998) yielded the best fit with the experimental data of all the produced biochar. Fluoroquinolone antibiotics were readily adsorbed onto sludge-derived biochar. These findings suggest a new approach for the pollution control of fluoroquinolone antibiotics using low-cost sludge-derived biochar.

We study the adsorption and desorption of chromium on two soils (a forest soil and a vineyard soil), both individually or after being combined with ground mussel shell, and on various materials (mussel shell, pyritic material from a dump site, and slate processing fines). The adsorption capacity depends mainly on the initial Cr concentration, on the pH, and on the abundance of noncrystalline Fe. The highest adsorption percentage (94 %) corresponds to the pyritic material, which also shows very low desorption rates (1.4 %), has the lowest pH, and has the highest concentration of noncrystalline Fe. The adsorption isotherms in most cases fit the Freundlich and Lineal models, rather than the Langmuir model, with no easily predictable maximum for chromium adsorption.

In this paper, we report on a field experiment being carried out in a Typic Eutrorthox. The experiment was initiated in the 1997–98 agricultural season as a randomized block design with four treatments (0, 5, 10, and 20 t ha⁻¹) of sewage sludge and five replicates. Compound soil samples were obtained from 20 subsamples collected at depths of 0–0.1 and 0.1–0.2 m. Cu, Fe, Mn, and Zn concentrations were extracted with DTPA pH 7.3; 0.1 mol L⁻¹ HCl, Mehlich-I, Mehlich-III, and 0.01 mol L⁻¹ CaCl₂. Metal concentrations were determined via atomic absorption spectrometry. Diagnostic leaves and the whole above-ground portion of plants were collected to determine Cu, Fe, Mn, and Zn concentrations extracted by nitric–perchloric digestion and later determined via atomic absorption spectrometry. Sewage sludge application caused increases in the concentrations of soil Cu, Fe, and Mn in samples taken from the 0–0.1 m depth evaluated by the extractants Mehlich-I, Mehlich-III, 0.01 mol L⁻¹ HCl and DTPA pH 7.3. None of the extractants provided efficient estimates of changes in Mn concentrations. The acid extractants extracted more Cu, Fe, Mn, and Zn than the saline and chelating solutions. The highest concentrations of Cu, Fe, and Zn were obtained with Mehlich-III, while the highest concentrations of Mn were obtained with HCl. We did not observe a correlation between the extractants and the concentrations of elements in the diagnostic leaves nor in the tissues of the whole maize plant (Zea mays L.).

The present work explores the sorption capacity of an inexpensive and highly available agricultural waste, rice husk, to remove mercury using realistic concentrations of this metal. The efficiency of the process was evaluated for two initial Hg(II) concentrations, one representing the maximum value for Hg discharges from industrial sectors (0.05 mg L-1), and the other ten times higher. A very small amount of rice husk (0.25 and 0.50 g L-1) was able to reduce the Hg(II) levels in more than 80 % for an initial concentration of 0.05 mg L-1 and in more than 90 % for 0.50 mg L-1, corresponding to residual concentrations of Hg(II) of 0.048 and 0.009 mg L-1, respectively. The biosorvent was reused in further cleaning treatments, maintaining the efficiency and high performance. The sorption kinetics of the Hg-rice husk system is well fitted by the Elovich model and the diffusion models suggested that, depending on the initial Hg(II) concentrations, the sorption process can be controlled by intraparticle diffusion or by both film and intraparticle diffusion. The equilibrium data are well described by the linear isotherm and the distribution coefficient found was 36.1 L g-1. © 2013 Springer Science+Business Media Dordrecht.

The development of human society entails increased industrial activity and consequently the release of a large number of chemical substances including solvents, detergents and pharmaceutical products which reach water bodies through the discharge of industrial effluents, damaging the organisms living in these ecosystems. This study aimed to determine oxidative stress induced on the common carp Cyprinus carpio by effluent from a pharmaceutical plant that manufactures nonsteroidal anti-inflammatory drugs. The median lethal concentration and subsequently the lowest observed adverse effect level were determined. Carp were exposed to the latter value (0.1173 %) for different exposure periods (12, 24, 48, 72 and 96 h), and the following biomarkers were evaluated in gill, brain, liver and blood: hydroperoxide content (HPC), lipid peroxidation (LPX), protein carbonyl content (PCC), and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Statistically significant increases with respect to the control group (P < 0.05) were observed in HPC, LPX and PCC particularly in gill of effluent-exposed specimens. SOD, CAT and GPx activity in gill also increased with respect to the control group. This particular industrial effluent is therefore concluded to induce oxidative stress on C. carpio, this damage being most evident in gill. © 2013 Springer Science+Business Media Dordrecht.