Chrysotile asbestos is progressively converted into a non-fibrous amorphous material by the chelating action of lichen metabolites

A natural deactivation of chrysotile asbestos occurs on serpentinite rocks where lichens selectively grow on the fibres and secrete metabolites, including oxalic acid, which, in the long term, turn the fibres into a non-toxic amorphous material.     

Technologies,challenges and perspectives of biogas production within an agricultural context. The case of China and Africa

Environment, Development and Sustainability - The use of fossil fuels in modern economies has been a success because of the low cost of fossil resources. However, the depletion of fossil reserves,...     

Five years of formaldehyde and acetaldehyde monitoring in the Rio de Janeiro downtown area – Brazil

The fuel matrix used in Brazil is unique around the world. The intensive use of hydrated ethanol, gasohol (gasoline with 25% v/v of ethanol), compressed natural gas (CNG), and biodiesel leads to a peculiar composition of the urban atmosphere. From 1998 to 2002 an increase in formaldehyde levels was observed and since then, a reduction. This work presents a monitoring campaign that was executed from March 2004 to February 2009 by sampling at early morning on every sunny Wednesday for a total of 183 samples. The results indicate a strong reduction in formaldehyde levels from 2004 (average of 135.8 μg m^?3 with SD 28.4 μg m^?3) to 2009 (average of 49.3 μg m^?3 with SD 27.4 μg m^?3). The levels of acetaldehyde showed a slight reduction from 2004 (average of 34.9 μg m^?3 with SD 8.0 μg m^?3) to 2009 (average of 26.8 μg m^?3 with SD 11.5 μg m^?3). Comparing the results with the concurrent evolution of the fleet and of fuel composition indicates that the observed formaldehyde levels could be associated with the increase in ethanol use and in CNG use by engines with improved technology over the first converted CNG engines. Modelling studies using the OZIPR trajectory model and the SAPRC chemical mechanism indicate that formaldehyde is the main ozone precursor in Rio de Janeiro and acetaldehyde is the forth one.     

Monitoring of sources and atmospheric processes controlling air quality in an urban Mediterranean environment

Different monitoring parameters (PM mass concentrations, number–size distribution, black carbon, gaseous pollutants, and chemical composition, among others) are currently used in air quality studies. Urban aerosols are the result of several sources and atmospheric processes, which suggests that a single monitoring technique is insufficient to quantitatively evaluate all of them.This study assesses the suitability of a number of monitoring techniques (PM mass concentrations, number and size distribution of ultra-fine particles, levels of gaseous pollutants, and a complete chemical characterization of PM₁₀ and PM_2.5) by examining the response of those techniques to the different emission sources and/or atmospheric processes affecting an urban Mediterranean area (Barcelona, NE Spain).The results of this work reveal that the PM mass, the number concentration and the chemical composition give different, but complementary, information. Whereas the mineral matter, a key atmospheric aerosol component across the Mediterranean, is not properly quantitatively assessed by measuring sub-micrometric particles, the monitoring of the number concentration is indispensable to interpret the origin of specific aerosol episodes. Furthermore, the chemical composition yields very relevant information to deduce the causes of specific pollution episodes.The number concentration of ultra-fine particles in urban areas is strongly dependent upon vehicle exhaust emissions, which may cause adverse health impacts. Moreover, urban Mediterranean environments are favourable to produce nucleation-mode particles (<20 nm) with photochemical origin. In those cases, these particles are expected to be of high solubility and consequently their toxicity may differ from that of traffic-generated ultra-fine particles. Thus, the use of a single monitoring parameter to evaluate the health effects seems to be not enough.     

Peracetic acid disinfection: a feasible alternative to wastewater chlorination.

The paper summarizes the results of a bench-scale study to evaluate the feasibility of using peracetic acid (PAA) as a substitute for sodium hypochlorite both for discharge into surface water and for agricultural reuse. Trials were carried out with increasing doses (1, 2, 3, 5, 10, and 15 mg/L) and contact times (6, 12, 18, 36, 42, and 54 minutes) to study disinfectant decay and bacterial removal and regrowth, using fecal coliform and Escherichia coli (E. coli) as process efficiency indicators. Peracetic acid decay kinetics was evaluated in tap water and wastewater; in both cases, PAA decays according to first-order kinetics with respect to time, and a correlation was found between PAA oxidative initial consumption and wastewater characteristics. The PAA disinfection efficiency was correlated with operating parameters (active concentration and contact time), testing different kinetic models. Two data groups displaying a different behavior on the basis of initial active concentration ranges (1 to 2 mg/L and 5 to 15 mg/L, respectively) can be outlined. Both groups had a "tailing-off" inactivation curve with respect to time, but the second one showed a greater inactivation rate. Moreover, the effect of contact time was greater at the lower doses. Hom's model, used separately for the two data groups, was found to best fit experimental data, and the disinfectant active concentration appears to be the main factor affecting log-survival ratios. Moreover, the S-model better explains the initial resistance of E. coli, especially at low active concentrations (< 2 mg/L) and short contact times (< 12 minutes). Microbial counts, performed by both traditional methods and flow cytometry, immediately and 5 hours after sample collection (both with or without residual PAA inactivation), showed that no appreciable regrowth took place after 5 hours, neither for coliform group bacteria, nor for total heterotrophic bacteria.     

Survey on fluoride, bromide and chloride contents in public drinking water supplies in Sicily (Italy)

Six hundred and sixty-seven water samples were collected from public drinking water supplies in Sicily and analysed for electric conductivity and for their Cl(-), Br(-) and F(-) contents. The samples were, as far as possible, collected evenly over the entire territory with an average sampling density of about one sample for every 7,600 inhabitants. The contents of Cl(-) and Br(-), ranging between 5.53 and 1,302 mg/l and between <0.025 and 4.76 mg/l respectively, correlated well with the electric conductivity, a parameter used as a proxy for water salinity. The highest values were found both along the NW and SE coasts, which we attributed to seawater contamination, and in the central part of Sicily, which we attributed to evaporitic rock dissolution. The fluoride concentrations ranged from 0.023 to 3.28 mg/l, while the highest values (only three exceeding the maximum admissible concentration of 1.5 mg/l) generally correlated either with the presence in the area of crystalline (volcanic or metamorphic) or evaporitic rocks or with contamination from hydrothermal activity. Apart from these limited cases of exceeding F(-) levels, the waters of public drinking water supplies in Sicily can be considered safe for human consumption for the analysed parameters. Some limited concern could arise from the intake of bromide-rich waters (about 3% exceeding 1 mg/l) because of the potential formation of dangerous disinfection by-products.     

Adsorption of pharmaceutical compounds and an endocrine disruptor from aqueous solutions by carbon materials

Adsorption has been used to study the removal of atenolol, caffeine, diclofenac and isoproturon, pharmaceutical compounds as emerging contaminants and an endocrine disruptor from ultrapure water and a municipal wastewater treatment plant effluent with three carbonaceous materials: activated carbon, multiwalled carbon nanotubes and carbon nanofibers. The adsorption capacities were studied in the temperature range of 25-65°C and pH range from 3 to 9. Several model isotherms were used to model the adsorption equilibrium data. Also, the competitive adsorption was evaluated.     

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Piracicaba River (São Paulo, Brazil)

A long-term study was conducted to evaluate Piracicaba River water (São Paulo state, Brazil) using different methodologies and organisms. During 1 year (February 2011 to January 2012), water samples were collected monthly at six different locations and exposed under laboratory conditions to the microcrustaceans Ceriodaphnia dubia and Ceriodaphnia silvestrii for 7 days and to the fish Danio rerio for 4 days to evaluate effects on reproduction and on gill morphology, respectively. Physical–chemical parameters of the water were also measured. Physical–chemical characteristics demonstrated decreasing water quality from upstream to downstream of the river. Effects on the reproduction of C. dubia and C. silvestrii were observed in 3 months (February and March 2011 and January 2012) and occurred in samples collected close to industrialized cities like Americana and Piracicaba. Evaluation of the gills showed normal function of the organ during all months, except in February, September, and October for some locations.     

Determination of Sulfur Oxides in the Flue Gases of the Pulping Processes

The body of information presented in this paper is directed to the operating personnel and process engineers employed in the power and recovery departments of a chemical pulping operation. The proper evaluation of the total analytical and sampling system (TASS), to be used in the determination of sulfur oxides is as important as a proper analytical and recording system (ARS). The presence of other sulfur gaseous compounds and particulates could greatly influence the results of the determination.

The analytical method employed determines sulfur dioxide and trioxide from an aliquot of the trapping solution, 3% hydrogen peroxide and 8 0% isopropyl alcohol respectively. The aliquot is titrated with barium perchlorate in the presence of Thorin indicator. The results of evaluating the method indicated negligible interference from the presence of hydrogen sulfide, mercaptans and nitrogen oxides. A blank correction of 15 parts per million (ppm) is recommended whenever 100 ppm of hydrogen sulfide or more are simultaneously present in the gas stream. Particulaies are shown to interfere either by addition or subtraction. Sulfate particulates that will add to the determination must be removed, but in doing so, care must be exerted to avoid surface-contacting conditions that promote reaction between carbonates and the sulfur oxides. The integrated method of sampling and analysis will permit determinations from a flue gas with sulfur oxides concentrations of 30 ppm and above. The relative standard deviation improves from 10% at 100 ppm SO₂ to 2.6% at 1000 ppm SO₂. In both cases, sulfides were present.