Chloride leaching from air pollution control residues solidified using ground granulated blast furnace slag

Ground granulated blast furnace slag (ggbs) has been used to solidify air pollution control (APC) residues obtained from a major UK energy-from-waste plant. Samples were prepared with ggbs additions between 10 and 50 wt% of total dry mass and water/solids ratios between 0.35 and 0.80. Consistence, setting time, compressive strength and leaching characteristics have been investigated. Results indicated that the highly alkaline nature of APC residues due to the presence of free lime can be used to activate ggbs hydration reactions. Increasing ggbs additions and reducing the water content resulted in increased compressive strengths, with 50 wt% ggbs samples having average 28 d strengths of 20.6 MPa. Leaching tests indicate low physical encapsulation and minimal chemical fixation of chloride in ggbs solidified APC residues. The results suggest that more than 50 wt% ggbs additions would be required to treat APC residues to meet the current waste acceptance criteria limits for chloride.     

Increased thyroid volume, prevalence of thyroid antibodies and impaired fasting glucose in young adults from organochlorine cocktail polluted area: outcome of transgenerational transmission?

In 137 females (F) and 94 males (M) aged 21-35 years from organochlorines (OCs) polluted area (POLL) increased thyroid volume (ThV), prevalence of antibodies to thyroperoxidase (TPOab), thyrotropin receptor (TRab) and of impaired fasting glucose (IFG) was found compared to 116 F and 107 M from background pollution area (BCGR). In F and M from POLL also strikingly increased level of PCBs, DDE and HCB was found. Such findings were compared to the generation of their parents aged 41-55 years consisting of 320F/213M from POLL and 406F/231M from BCGR. However, in spite of strikingly lower level of those OCs in young adults from POLL, they showed about the same prevalence of adverse health signs as the old generation. From such reason 44 young F and 40 young M with lowest PCBs level from POLL were selected to obtain nearly the same PCB level as found in all young F and M from BCGR. In such PCB adjusted groups the prevalence of TPOab, TRab, IFG and increased ThV was still significantly higher than that in all young subjects from BCGR. At the same time, also the level of DDE and HCB in such PCBs adjusted groups was considerably lower. It was concluded that such adverse effects in young adults from POLL possibly did not result from their actual OCs levels, but very likely from their exposure to high OCs levels of their mothers during their prenatal and perinatal life. Thus, the data may be compatible with present views on transgenerational transmission of endocrine disruptors action.     

Recent advances in the photocatalytic reduction of carbon dioxide

Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO₂, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO₂ emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO₂ capture, storage and utilization. For instance, photocatalytic reduction of CO₂ into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO₂. Then we review the photocatalytic conversion of CO₂ by TiO₂, modified TiO₂ and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO₂ photocatalytic reduction are presented.     

Biosorbents for solid-phase extraction of toxic elements in waters

Some trace metals are highly toxic for the environment. There is therefore a need for reliable methods for the determination of metals at trace levels. To this end, new sample pretreatment methods such as separation, preconcentration and speciation prior to the determination of metal ions have developed rapidly. Biosorption has become a major tool for solid-phase extraction methods. This review covers selected biosorbents such as algae, bacteria, filamentous fungi and yeasts, as new sorbents used in the solid-phase extraction of metal ions from various water sample matrices. A survey of the literature over 2004-2014 shows possible applications of selected new sorbents available for use in trace metal analysis in waters using solidphase extraction. We highlight the preconcentration of the toxic elements prior to their determination by atomic spectrometry.     

Redox processes in water remediation

Groundwater is the main source of drinking water and water for agricultural and industrial usage. Therefore, groundwater contamination is prevented and contaminated groundwater is remediated to protect public health and the environment. Methods to remediate groundwater contamination have been recently developed. The use of redox processes in water remediation technologies has not been properly reviewed. Numerous water remediation technologies, such as ultrasonication, bioremediation, electrokinetics and nanotechnology, are closely related to redox processes. Redox processes control the chemical speciation, bioavailability, toxicity, mobility and adsorption of water pollutants in environment. Here, we review (1) general introduction of redox processes, (2) applicability of redox processes in water remediation, and (3) catalytic enhancement of redox potentials to explore its wide applicability in environmental remediation.     

High boron removal by functionalized magnesium ferrite nanopowders

Hydroxyl-enriched materials are promising boron adsorbents. However, the use of these materials is hampered by issues of separation, recovery, and selectivity, notably due to the presence of interfering ions. Therefore, we synthesized here a cheap magnetic nanopowder, which was further functionalized with polyvinyl alcohol and glycidol to produce boron-selective adsorbents. We studied their selectivity and removal efficiency using batch and fixed-bed systems. Sorption was studied at both concentrated and trace amounts of boron. Results show that nanopowders have 5.3–6.5 nm pore sizes and 145–203 m²/g surface areas, using Brunauer–Emmett–Teller analysis. Polyvinyl alcohol-functionalized particles removed 93 % of boron at 5 mg/L at pH 7 in 30 min, whereas only 68 % of boron was removed by glycidol-functionalized particles. However, at higher boron concentration, of 50 mg/L, glycidol-functionalized particles showed higher adsorption affinity of 68.9 mg/g. We conclude that internal hydroxyl groups of polyvinyl alcohol-functionalized particles are less accessible at higher boron concentration. This is the first report on magnesium ferrites for boron recovery. The spent adsorbents were separated easily from the aqueous media by an external magnet and repeatedly used. Overall, our findings demonstrated that the hydroxyl-enriched magnetic nanopowders are a better alternative to the existing boron adsorbents regarding magnetic separation, reusability, and selectivity.     

High amounts of free aromatic amino acids in the protein-like fluorescence of water-dissolved organic matter

Fluorescence spectroscopy is widely used to study water pollution. The fluorescence of water natural organic matter can be classified into two groups: the protein-like fluorescence originating from aromatic amino acids and the humic fluorescence originating from humic substances. Actually, the precise molecular origin of the protein-like fluorescence is unknown because this fluorescence may be caused by either free amino acids, peptides or proteins. Therefore, we studied the molecular origin of the protein-like fluorescence of Suwannee River natural organic matter and fractions A, B and C + D obtained by size exclusion chromatography/polyacrylamide gel electrophoresis. Fractions were analyzed by reversed-phase high-performance liquid chromatography. The electrophoretic mobilities of fractions varied in the order C + D > B > A and the molecular size in the opposite order. Our results show that the protein-like fluorescence is almost exclusively located in high molecular size fraction A and medium molecular size fraction B. Retention times and fluorescence emission spectra of authentic free aromatic amino acids tyrosine and tryptophan were identical with the retention times and emission spectra of several chromatographic peaks of fractions A and B. More than 50 % of the protein-like fluorescence is due to free aromatic amino acids incorporated in water natural organic matter.     

Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

Water pollution by pharmaceutically active compounds is an emerging issue. Toxicological studies reveal that pharmaceuticals are indeed toxic for living organisms. The lack of suitable treatment technology for the complete removal of pharmaceuticals is therefore a major challenge. Advanced oxidation processes are emerging removal techniques that have many advantages versus conventional technologies. Many studies indicate that advanced oxidation processes, either in single or in combination with other degradation techniques, can enhance the degradation of pharmaceuticals in aqueous solutions. Here, we review the degradation of pharmaceuticals by sonolysis, an oxidation processes using ultrasound. In this technique, hydroxyl radicals are generated by pyrolytic cleavage of water molecules. We review the influence of operational parameters, additives and hybrid techniques on the degradation of pharmaceuticals. The maximum degradation of organic compounds was observed in the frequency range of 100–1000 kHz, which is in the high-frequency medium-power ultrasound. Even though almost all the experiments presented more than 90 % removal and good biodegradability of the target compound, good mineralization and the toxicity removal were hardly achieved. The efficiency of the degradation varies with water matrixes and varying pH. Major pathways of degradation are hydroxylation, dehalogenation, demethylation, decarboxylation, deamination, etc. More hybrid techniques have to be developed to scale up the application of ultrasound.