The aim of the present work was to determine the effect of the simultaneous adsorption of lead(II)-cadmium(II), lead(II)-phenol, and cadmium(II)-phenol by activated carbon cloths (ACCs). Three commercial ACCs were characterized and tested for individual metal adsorption, and competitive adsorption experiments were carried out with the best ACC (AW1104). The specific surface areas of all ACCs were >1000 m²/g, yet only AW1104 presented a high content of acidic sites (1.0 meq/g). Competitive adsorption experiments indicate that cadmium uptake is strongly affected by the presence of lead. This can be attributed either to a more favorable hydroxyl complexation of Pb(II) (that adsorbs strongly),or to the smallest hydrated radius of the Pb(II) molecule (that more easily diffuses). On the contrary, lead uptake was not considerably decreased in the presence of an equimolar cadmium concentration, indicating that AW1104 is more selective for Pb(II) than for Cd(II). Also, the presence of phenol causes a decrease in the heavy metal adsorption capacity, especially for cadmium (40 %). The former might be due to adsorbed phenol, which creates steric hindrance for cations to adsorb on specific oxygenated groups on the ACC. On the other hand, when heavy metals adsorb on the ACC surface, they stabilize the repulsive forces on the surface of the ACC for phenol adsorption, resulting in an increase of the adsorption capacity.

Chemical methods have been used for the remediation of arsenic (As)-contaminated water; however, ecological consequences of these methods have not been properly addressed. The present study evaluated the effects of the Fe-oxide-coated sand (IOCS) remediation method on As toxicity to freshwater organisms (Lemna disperma, Chlorella sp. CE-35, and Ceriodaphnia cf. dubia). The As removal efficiency by IOCS decreased substantially with time. The IOCS remediation method was less effective at suppressing the toxicity of Asⱽ than Asᴵᴵᴵ to L. disperma but was highly effective in reducing both the Asᴵᴵᴵ and Asⱽ toxicity to C. cf. dubia. The growth of Chlorella sp. was significantly higher (p < 0.05) in remediated and pre-remediated water than in controls (non-As-contaminated filtered Colo River water) for Asᴵᴵᴵ, while the opposite was observed for Asⱽ, indicating that Asⱽ is more toxic than Asᴵᴵᴵ to this microalga. Although the IOCS can efficiently remove As from contaminated water, residual As and other constituents (e.g. Fe, nitrate) in the remediated water had a significant effect on freshwater organisms.

Copper hydrotalcites with and without adsorbed chlorophyllin exhibit a bactericidal effect that depends on the copper release and the basicity, which can be tuned through the chlorophyllin adsorption. The prepared solids performed well for the elimination of Escherichia coli, Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus bacteria. The results showed that the copper-containing hydrotalcite with the adsorbed chlorophyllin is the most active material. Wastewaters from a metal industry were treated with these hybrid compounds, and the bactericidal effect was comparable with the results reported using more complex methods such as photocatalysis. Furthermore, one main advantage of these hybrid compounds is its low human toxicity compared with silver-containing materials.

Enteric viruses enter surface waters through discharge of sewage treatment plants. They have a high environmental resistance and persistence and have low infectious doses. The aim of this study was to investigate the efficiency of polishing pond in the removal of viruses and bacteria. The samples were taken approximately once a week at the influent of secondary treatment (n = 39), effluent of secondary treatment (n = 39), and polishing pond (tertiary treatment, n = 29). Human adenoviruses (HAdV) were detected in 82–100 % of wastewater samples, whereas 62–79 % of the samples were positive for human polyomavirus (HPyV). The median concentrations ranged from 6.8 × 10³ genome equivalents/l (HAdV) to 6.0 × 10³ genome equivalents/l (HPyV). The concentration of HAdV and HPyV did not change significantly during the wastewater treatment. For somatic coliphages and bacteria an overall reduction of 1.84–2.65 log₁₀ has been detected. Based on the data collected, this type of tertiary treatment achieved a significant reduction in bacteria and phages, but not for viruses.

Bacteria that harbor the mer operon in their genome are able to enzymatically reduce mercury (II) to the volatile form of mercury Hg (0). Detoxification of contaminated waste by using these bacteria may be an alternative to conventional methods for mercury removal. Residual glycerol from the biodiesel industry can be used as a carbon source to accelerate the process. This work shows for the first time the feasibility of using residual glycerol as a carbon source for Hg removal by bacteria prospected from contaminated environments. Eight bacterial isolates were able to remove mercury and degrade glycerol in mineral medium and residual glycerol. Mercury removal was monitored by atomic absorption spectroscopy and glycerol degradation by high performance liquid chromatography. The best results of mercury removal and glycerol degradation were obtained using isolates of Serratia marcescens M25C (85 and 100 %), Klebsiella pneumoniae PLB (90 and 100 %), Klebsiella oxytoca (90 and 100 %), and Arthrobacter sp. U3 (80 and 75 %), with addition of 0.5 g L⁻¹ yeast extract. The Arthrobacter sp. U3 isolate is common in soils and has proven to be a promising candidate for environment applications due to its low pathogenicity and higher Hg removal and glycerol degradation rates.

A wide variety of application of nanoparticles (NPs) in recent years has raised their possible entrance into the environment so that can affect living components of ecosystems. There is no comparative study on the long-term effects of a wide range of concentrations of NPs, related bulk particles (BPs), and corresponding metal ions on different traits of the plants. The present study has investigated comparative effects of zinc oxide (ZnO) NPs, ZnO BPs, and zinc ions (Zn²⁺) on rapeseed (Brassica napus L.) after long-term exposure to a wide range of concentrations. The inhibitory effects of treatments on the growth of B. napus were in the order Zn²⁺ >> ZnO BPs > ZnO NPs. Results showed the significant changes in the antioxidant enzyme activities, total chlorophyll, soluble proteins, proline, and soluble sugars of the leaves in response to the treatments. However, total phenolic compounds were not affected significantly by any treatment. Overall, in the present study, the toxicity of ZnO NPs on B. napus was lower than those of Zn²⁺ or ZnO BPs. Results indicate that adverse effects of ZnO NPs or BPs on B. napus may be due in part to the toxic effects of Zn²⁺ ions dissolution, probably induced by root exudates, or due o the physical interaction of ZnO particles with roots and induction of structural and functional disorders.

A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.

Calcium alginate beads entrapping a mixture of Fe(0) and nanosized magnetite (NMT) were prepared and evaluated for their capability to reduce nitrate in groundwater. Microscopic and spectroscopic analyses of the beads revealed that clusters of Fe(0)/NMT were entirely embedded in alginate polymer matrix containing a large number of carboxylic and hydroxyl functional groups. The extent of nitrate reduction increased with increasing content of Fe(0) and NMT in the beads, but there was a critical NMT mass limit relative to Fe(0) mass where no further increase in nitrate reduction occurred. The beads showed slower nitrate reduction kinetics than bare Fe(0)/NMT but had comparable capacity in overall nitrate removal. Nitrate reduction increased proportionally with an increase in bead dosage to give a maximum removal of 94.5 % at 37.5 g L⁻¹ in 48 h. Nitrate reduction with 50 g L⁻¹ beads achieved completion of two reduction cycles in 72 h to reduce 2.19 mM nitrate to less than 0.71 mM (10 mg-N L⁻¹) in each cycle. The overall results demonstrated that the beads developed in this study have a potential utility in remediation of nitrate in groundwater.

Nanoscale zero valent iron (NZVI) supported on beta zeolite was synthesized by refined method for the removal of Sb(III) and characterized with TEM-EDX, XRD, XPS, BET, and Zetasizer. The results showed that NZVI existed as apparent ones doping on surface of beta zeolite (average size 20–40 nm) and fine ones formed in structure of beta zeolite (<1 nm). Compared to NZVI, NZVI-zeolite showed enhanced antimony removal ability and higher iron efficiency due to its better dispersibility and smaller size. Adsorption and reduction ability of iron played main roles in the antimony removal. The removal isotherm was better fitted by Freundlich model. According to XPS analysis, reduction of Sb(III) happened rapidly and Sb(0) took more than 80 % in final products, which was higher compared with NZI. Iron transformation accompanied with antimony removal was identified by XRD and XPS, which caused antimony reduction and facilitate further immobilization of removed antimony. The iron oxides encapsulated antimony in their own structure and beta zeolite which they adhere. The theoretical model about the process was proposed to illustrate NZVI-zeolite enhanced antimony removal ability.

Dioxins are a group of persistent organic pollutants with varying degrees of toxicity. To determine the effects of polychlorinated dibenzo-p-dioxins pollution on soil nutrition, soil carbon dioxide (CO₂) emission, and plant growth, soils and mung bean seedlings were experimentally subjected to 1,2,3,7,8-pentachlorodibenzo-para-dioxin (PeCDD). The results showed that: (i) Low dose of PeCDD treatments led to a significant decrease in the soil organic matter content and an increase in the hydrolyzable nitrogen content, while the contents of available phosphorus and exchangeable potassium decreased significantly at high doses of PeCDD (≥20 ng kg⁻¹). (ii) The soil CO₂release rate was gradually increased from treatments with 10 to 20 ng kg⁻¹PeCDD, but decreased significantly with 30 ng kg⁻¹PeCDD treatment after 25 days exposure. With prolonged exposure time, the soil CO₂emission after all treatments declined heavily, along with the difference among different treatments. (iii) Low dose of 10 ng kg⁻¹PeCDD resulted in significant reductions of malondialdehyde (MDA) content and electrolyte leakage conductivity and increases in the contents of chlorophyll and soluble protein and fresh biomass of mung bean seedlings. On the contrary, high doses of PeCDD (≥20 ng kg⁻¹) treatments showed opposite effects on the above parameters of seedling growth. The results suggested that high doses of PeCDD contamination (≥20 ng kg⁻¹) posed potential negative effects on the cycling processes of soil nutrients, which were probably due to the inhibitory on soil microbial activity, and induced phytotoxicity on seedling growth, although slight stimulations of soil microbial activity and mung bean seedling growth were found at low doses of PeCDD. Therefore, more efforts are needed to ensure the dioxin contamination below the toxic concentration of 20 ng TEQ kg⁻¹in farmland soil.