A serial enrichment culture has been grown in an alkaline Fe(III)-citrate-containing medium from an initial inoculum from a soil layer beneath a chromium ore processing residue (COPR) disposal site where Cr(III) is accumulating from Cr(VI) containing leachate. This culture is dominated by two bacterial genera in the order Clostridiales, Tissierella, and an unnamed Clostridium XI subgroup. This paper investigates the growth characteristics of the culture when Cr(VI) is added to the growth medium and when aquifer sand is substituted for Fe(III)-citrate. The aim is to determine how the availability and chemical form of Fe(III) affects the growth of the bacterial consortium, to determine the impact of Cr(VI) on growth, and thus attempt to understand the factors that are controlling Cr(III) accumulation beneath the COPR site. The culture can grow fermentatively at pH 9.2, but growth is stronger when it is associated with Fe(III) reduction. It can withstand Cr(VI) in the medium, but growth only occurs once Cr(VI) is removed from solution. Cr(VI) reduced the abundance of Tissierella sp. in the culture, whereas the Clostridium XI sp. was Cr(VI) tolerant. In contrast, growth with solid phase Fe(III)-oxyhydroxides (present as coatings on aquifer sand) favoured the Tissierella C sp., possibly because it produces riboflavin as an extracellular electron shuttling compound allowing more efficient electron transfer to solid Fe(III) phases. Thus, it is suggested that bacterially mediated Cr(III) reduction in the soil beneath the COPR site is dependent on Fe(III) reduction to sustain the bacterial community.

In this study, the samples of the spatial soil and organs of the grapevine (Vitis vinifera) cultivar Tamjanika were collected from the selected zones near the Mining and Smelting Complex Bor (East Serbia). They were analyzed by ICP-OES to determine the content of Cu, Zn, Pb, As, Cd, and Ni with the aim of ascertaining if these data may help in the assessment and improvement of the quality of environment in polluted areas such as Bor and its surrounding area. The results obtained from the calculated biological and enrichment factors, as well as from the Pearson correlation study and hierarchical cluster analysis confirmed that very useful information is recorded in plant organs: root, stem, leaves, and fruit. Yet, when the atmospheric pollution is the sphere of interest, the most informative data are found in unwashed leaves. The results of this study indicated also that the investigated plant species has some highly effective strategies involved in tolerance to the stress induced by heavy metals, which makes it an excellent candidate for phytostabilization purposes. Planting of this grapevine cultivar can be recommended in all areas that are severely polluted with heavy metals.

SrCO₃ was formed and added as a carrier into copper-based catalyst (CuZnAl catalyst) prepared by hydrothermal method before the catalyst incorporates with HZSM-5. The CuZnAlSr catalyst was characterized by SEM, BET, XRD, IR, and activity-evaluation system in a fixed-bed tubular reactor equipped with chromatograph (GC). The conversion of CO₂ reaches 30.30 %, and the overall yield of methanol and dimethyl ether is 27.80 %. Catalytic property as to CO₂ conversion has only slight decrease even up to 150 h of reaction time. The addition of SrCO₃ enhanced the activity of the catalyst through providing a tridimensional frame and electron transfer bridge.

The intensive pig production has been causing huge amounts of pig slurry with high content of potential pollutants. However, there is a lack of information on the efficiency of combined techniques applied to pig slurry purification. The objective of this research was to assess the pollutant removal efficiency and pathogenic microorganism decrease using mechanical treatments, phytoextraction, and microalgae bioremediation. The purification system was located in the southeast of Spain. Physico-chemical and microbiological parameters were studied in each module of treatment. We observed significant declines for total suspended solids (89 %), settleable solids (100 %), chemical oxygen demand (91 %), biochemical oxygen demand (90 %), total phosphorus (97 %), copper (96 %), zinc (92 %), total nitrogen (89 %), total coliforms (78 %), fecal coliforms (70 %), fecal streptococcus (75 %), Salmonella, Shigella, and Escherichia coli (100 %) in the final effluent of the combined purification system. This survey pointed out the effectiveness of phytoextraction and bioremediation treatments. The results indicated the high efficiency of the purification system, minimizing environmental and human risks.

Chelating reagents impregnated or incorporated into solid sorbents have been widely used in the preconcentration of metal species. In this work, polystyrene-divinylbenzene functionalized with 2-hydroxyacetophenone was used for the preconcentration and determination of cadmium, cobalt, and nickel in sediment samples by flame atomic absorption spectrometry. The sorbent was characterized by infrared spectroscopy and scanning electron microscopy. The influence of variables on the extraction of the metal ions was studied. Under optimized conditions, the method showed enrichment factors of 20 (Cd), 37 (Co), and 32 (Ni) and detection limits of 0.1 (Cd), 0.8 (Co), and 0.6 μg L⁻¹(Ni). The accuracy of the method was tested by analysis of a certified reference material composed of inorganics in marine sediment (NIST 2702). The method was applied to the determination of cadmium, cobalt, and nickel in real sediment samples. Cadmium and cobalt were not found in the sediment samples. Nickel was found in two samples (5.2 and 8.2 μg g⁻¹).

The sorption behavior of cobalt by a sodium-modified zeolite-rich tuff was investigated using cobalt solutions prepared with water from the cooling system of a nuclear reactor. The sorption kinetics shows that the equilibrium was reached in less than 20 h. The isotherms showed that the sorption capacity of the sodium-modified zeolite-rich tuff for cobalt was 20.73 mg/g at 60 °C. The pH affects the sorption capacity of the sodium-modified zeolite-rich tuff for cobalt. The sorption capacity of the sodium-modified zeolite-rich tuff for cobalt was higher using nuclear purity water than water from other aqueous matrices.

Several laccases from different sources have been used in dye decolourization processes. However, only in a reduced number of studies have efforts been done to identify the metabolites produced by the enzymatic treatment as well as to evaluate the toxicity of degradation products. Taking these gaps into account, the objective of this work was to use a laccase from Ganoderma lucidum in the decolourization of the synthetic dye Congo red (C.I. No. 22120, Direct Red 28), largely used in the textile industry. After 6 h of treatment at pH 4.0 and 40 °C, the enzyme was able to decolourize 80 % of Congo red. Fourier transform infrared spectroscopy (FTIR), photoacoustic spectroscopy (PAS) and mass spectrometry allow concluding that laccase effectively changed the structure of Congo red, reducing the colour by modifying the chromophore groups and other parts of the molecule. Several degradation products with m/z ⁺ ranging from 298 to 745 were identified. It is proposed that the first degradation step could be an asymmetric cleavage of the azo bond present in the Congo red structure forming the intermediate with m/z ⁺ 298. The results also suggest a reduction in the toxicity of Congo red after laccase treatment, as indicated by the lettuce seed germination model. In conclusion, G. lucidum laccase could be used in a novel azo dye bioremediation strategy.

Here, we report on the ability of two different water treatment residues, a Fe-based (Fe-WTR) and an Al-based (Al-WTR) ones, to accumulate Cd(II) and Zn(II) from aqueous solutions at different pH values (pH 4.5, 5.5, and 7.0). Fe-WTR showed a greater Zn(II) and Cd(II) sorption capacity than Al-WTR at all the pH values investigated, in particular at pH 7.0 (e.g., ∼0.200 and ∼0.100 mmol g⁻¹ of Me(II) sorbed by Fe- and Al-WTR at pH 7.0, respectively). The greater capacity of the Fe-WTR to accumulate Me(II) seems to be linked to its higher content of iron and manganese ions and to its higher CEC value compared to Al-WTR. The role of the inorganic and organic fractions of WTRs in metal sorption was also assessed. A higher affinity of Cd(II) with respect to Zn(II) toward functional groups of the organic matter of both WTRs was observed, while Zn(II) showed a stronger association with the inorganic phases. The sorption of both metal ions appeared mainly governed by the formation of inner-sphere surface complexes with the inorganic and organic phases of WTRs, as suggested by the sequential extraction data.

Pig farms have achieved importance in the last few decades from the perspective of environment protection as a consequence of the intensive rearing systems in livestock production. Ammonia (NH₃) and greenhouse gases (GHG), such as methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O), are emitted from slurry storage at farm prior to land application, but little is known about these losses under on-farm conditions in Spain. This study assessed the influence of management and environmental parameters on NH₃ and GHG emissions from slurry storage in spring and autumn. Gas emissions were measured in a commercial pig-fattening farm from two lagoons (1000 and 768 m³ capacity, respectively) during 30 days by the floating dynamic chamber system in spring and autumn 2011 (average temperature 19 and 9 °C, respectively). Low NH₃ and CH₄ emissions were registered in spring (range 10–406 and 3–17 mg m⁻² min⁻¹, respectively) probably as a result of low pH values of stored slurry (6.5 to 7.0) and rainfall. High variability on NH₃, CH₄, and CO₂ emissions was observed as a result of differences in temperature and rainfall. No NH₃ emission and low CH₄ and CO₂ emissions were observed in autumn (average 1.2 ± 0.9 and 27 ± 22 mg m⁻² min⁻¹, respectively). Slurry loading operations increased NH₃ losses from storage.

Microbial Cr(VI) reduction is a significant process in detoxification of Cr(VI) pollution. In this study, a new Cr(VI)-reducing bacterial strain, Cr-4, was isolated from soil around the chromium-containing slag. The analysis of the 16S ribosomal RNA (rRNA) gene sequence revealed that the newly isolated strain was closely related to Bacillus anthracis. The response to Cr(VI) stress and reduction capacity of the isolate were investigated. Cell growth decreased with the increase of Cr(VI) concentration. Cell morphology varied and cell growth was inhibited remarkably in the presence of 125 mg/L Cr(VI). The strain grew well and removed Cr(VI) effectively at a Cr(VI) concentration lower than 50 mg/L. Cr(VI)-reducing activity was inhibited by Zn²⁺, while significantly stimulated by Cu²⁺. The activity of Cr(VI) reduction by cell-free extract was demonstrated. Total chromium analysis and the energy-dispersive X-ray analysis (EDAX) spectrum revealed that Cr(VI) removal was caused mainly by microbial reduction rather than by biosorption and the main part of the reduced Cr(III) existed as soluble form in solutions.