Evaluation of the effects of PFAS soil adsorption and transformation in the presence of divalent cations under ambient conditions

A bench‐scale study was conducted to evaluate the effect of divalent cations on the adsorption of perfluoroalkyl and polyfluoroalkyl substances (PFAS) onto soil particles. The study entailed batch testing of a synthetic soil mixture under a range of Epsom salt (soluble magnesium sulfate heptahydrate) concentrations. The synthetic soil was produced using a mix of sand, silt, clay, and organic matter that then was mixed and saturated with water collected from a PFAS‐impacted water source. The results indicate that variable concentrations of magnesium (divalent cation) had a minor effect on the sorption of perfluorooctane sulfonate with the highest sorption occurring in the strongest solution of Epsom salt. An unanticipated result of the test involved apparent biomediated transformation of polyfluorinated alkylated sulfonates (fluorotelomers or FTS) to perfluorooctanoic acid, perfluoroheptanoic acid (PFHpA), and perfluorononanoic acid. We believe this is the first time the complete transformation of 6:2 FTS to PFHpA has been observed and reported under ambient surface water‐like conditions within 6 months, a relatively short timeframe.     

Measurement of BTEX (benzene,toluene, ethybenzene,and xylene) levels at urban and semirural areas of Algiers City using passive air samplers

The study presents the levels of air pollution by aromatic organic compounds BTEX (benzene, toluene, ethylbenzene, o-, m-, and p-xylenes) in the city of Algiers. The sampling was carried out using Radiello passive sampler. Three sampling campaigns were carried out in roadside, tunnel, urban background, and semirural sites in Algiers. In order to determine the diurnal mean levels of air pollution by BTEX to which people are exposed, a modified passive sampler was used for the first time. In addition, monitoring of pollution inside vehicles was also made. In the spring of 2009, more than 27 samplings were carried out. In the background and road traffic sites the Radiello sampler was exposed for 7 days, whereas the time exposure was reduced to 1 day in the case of the vehicle as well as the tunnel. The results indicate that average benzene concentrations in the roadside and inside vehicle exceed largely the limit value of 5 μg m^?3 established by the European Community (EC). On the other hand, it has been noticed that the concentration levels of other BTEX are relatively high. Also, in order to identify the origin of emission sources, ratios and correlations between the BTEX species have been highlighted. This study shows that road traffic remains the main source of many local emission in Algiers.

Implications The vehicle fleet in Algeria is growing rapidly since the 1990s following economic growth and is responsible for the increasing air pollution in large cities. Because there are no data collection of BTEX carried out by national air quality network, all environmental and transportation policies are based on European emissions standards, but national emission standards are currently not in place. This work will contribute to the analysis of real emissions of BTEX in Algiers, for the development of management and for assessment of population exposure variation depending on the location in the city of Algiers.     

Preparation of aluminium-magnesium alloys and some valuable salts from used beverage cans

The purpose of this work is to recover standard aluminium-magnesium alloy(s) and some valuable salts from used beverage cans (UBCs). The suggested method updated the current recycling technology by augmenting removal of the coating paint, decreasing magnesium loss during melting process and improving hydrochloric acid leaching of the formed slag. Iron impurity present in the leaching solution, was removed by oxidation using oxygen gas or hydrogen peroxide and filtered as goethite. Results obtained revealed that a mixture of methyl ethyl ketone/dimethyl formamide entirely removes the paint coating at room temperature. The process compares favorably to the current methods involving firing or swell peeling. The coating decomposes to titanium dioxide by heating at 750 degrees C for 30 min. Standard compositions of Al-Mg alloys are formulated using secondary magnesium. The extent of recovery (R) of these alloy(s) is a function of the melting time and temperature and type of the flux. The maximum (R) value amounts to 94.4%. Sodium borate/chloride mix decreases magnesium loss to a minimum. The extent of leaching valuable salts from the slag increases with increasing the molarity, stoichiometric ratio and leaching temperature of the acid used. Removal of iron is a function of the potential of the oxidation process. Stannous chloride has been recovered from the recovered and dried salts by distillation at 700-750 degrees C.     

Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps

This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 degrees C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 degrees C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 degrees C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.     

On-board measurement of emissions from liquefied petroleum gas, gasoline and diesel powered passenger cars in Algeria

On-board measurements of unit emissions of CO,HC,NOx and CO2 were conducted on 17 private cars powered by different types of fuels including gasoline,dual gasoline–liquefied petroleum gas(LPG),gasoline,and diesel. The tests performed revealed the effect of LPG injection technology on unit emissions and made it possible to compare the measured emissions to the European Artemis emission model. A sequential multipoint injection LPG kit with no catalyst installed was found to be the most efficient pollutant reduction device for all of the pollutants,with the exception of the NOx. Specific test results for a sub-group of LPG vehicles revealed that LPG-fueled engines with no catalyst cannot compete with catalyzed gasoline and diesel engines. Vehicle age does not appear to be a determining parameter with regard to vehicle pollutant emissions. A fuel switch to LPG offers many advantages as far as pollutant emissions are concerned,due to LPG's intrinsic characteristics.However,these advantages are being rapidly offset by the strong development of both gasoline and diesel engine technologies and catalyst converters. The LPG's performance on a chassis dynamometer under real driving conditions was better than expected. The enforcement of pollutant emission standards in developing countries is an important step towards introducing clean technology and reducing vehicle emissions.     

Recyclables recovery of europium and yttrium metals and some salts from spent fluorescent lamps

Europium and yttrium metals and some valuable salts were recovered from the powder coating the inner surface of the glass tubes of fluorescent lamps. The tubes were broken under 30% aqueous acetone to avoid emission of mercury vapor to the atmosphere, and the powder was collected by brushing. Metals available in the powder were pressure leached using sulfuric/nitric acid mixture. Sulphate salt of europium and yttrium so obtained was converted to thiocyanate. Trimethyl-benzylammonium chloride solvent was used to selectively extract Eu and Y from the thiocyanate solution. The metal loaded in the organic solvent was recovered by N-tributylphosphate in 1M nitric acid to produce nitrate salts of Eu and Y. Europium nitrate was separated from yttrium nitrate by dissolving in ethyl alcohol. The isolated powder contained 1.62% europium oxide, 1.65% yttrium oxide, 34.48% calcium sulphate, 61.52% Ca orthophosphate and 0.65% other impurity metals by weight. Autoclave digestion of the powder in the acid mixture for 4h at approximately 125 degrees C and 5 MPa dissolved 96.4% of the yttrium and 92.8% of the europium. Conversion of the sulphate to thiocyanate is favoured at low temperature. Extraction of Eu and Y from the thiocyanate solution attained its maximum at approximately 80 degrees C. N-tributylphosphate in 1N nitric acid at 125 degrees C achieved a stripping extent of 99%. Thermal reduction using hydrogen gas at 850 degrees C and 1575 degrees C produced europium and yttrium metals, respectively. A metal separation factor of 9.4 was achieved. Economic estimation revealed that the suggested method seemed feasible for industrial applications.     

On-board emission measurement of high-loaded light-duty vehicles in Algeria

A sample of eight private gasoline and diesel conventional light-duty vehicles (LDVs) in use with various ages, carrying a load of 460 kg, were tested on a representative trip in the traffic flow of the city of Blida to obtain emission factors representing the actual use conditions of Algerian LDVs. The gas sampling system (mini-constant volume sampling) as well as the analyzers are carried on-board the vehicle. Around 55 tests were conducted during 3 months covering more than 480 km under various real driving conditions. The mean speed downtown is about 16.1 km/hr with a rather low acceleration, an average of 0.60 m/sec2. For each test, kinematics are recorded as well as the analysis of the four emitted pollutants carbon dioxide, carbon monoxide, oxides of nitrogen, and total hydrocarbons. Emission factors were evaluated according to speed for each category of gasoline and diesel engines. The influence of some parameters such as cold/hot start, age of vehicle and its state of maintenance are discussed. Results are compared with the European database ARTEMIS for comparable vehicles. These measurements contribute to the development of unit emission of the vehicles used in Algeria, which are necessary for the calculation of emission inventory of pollutants and greenhouse gases from the road transportation sector. The unit emissions constitute a tool of decisionmaking aid regarding the conception of new regulations of vehicle control and inspection in Algeria and even in similar developing countries.     

Per‐ and polyfluoroalkyl substances in environmental sampling products: Fact or fiction?

Can per‐ and polyfluoroalkyl substances (PFAS) be transferred from the common field and other commercial products during sampling? Special handling and care are always advised when collecting samples for PFAS analysis to avoid sample contamination. The potential presence of PFAS in common consumer products and in equipment typically used to collect environmental samples, coupled with the need for very low reporting limits heightens this concern. In this paper, the authors investigate what the potential for cross‐contamination is from a number of commonly used products, with the emphasis on evaluating what the possible worst‐case scenario for cross‐contamination could be. Polytetrafluoroethylene (PTFE), low‐density polyethylene (LDPE), and high‐density polyethylene (HDPE) tubing, pump bladders, and other materials are evaluated along with associated products such as aluminum foil and plastic storage bags. In the experimental design of this study, the products themselves are not analyzed directly for PFAS. Rather, a series of experiments are performed utilizing a leaching procedure to evaluate the potential for cross‐contamination and false‐positive environmental sampling results. This study was performed in a series of experimental batches over the course of a 1‐year period. Analytical results are presented along with experimental observations and recommendations.     

Estimation of the intrinsic maximum substrate utilization rate using batch reactors with denitrifying biofilm: a proposed methodology.

A method for estimation of the maximum substrate utilization rate (q(max)) using batch reactors with denitrification biofilm was introduced and compared with the traditional method of using batch reactors with suspended growth for q(max) estimation. The values of q(max) obtained from the suspended-growth reactors (0.69 to 0.71 g N/g volatile suspended solids [VSS] x d) and from the attached-biomass reactors (0.74 to 0.85 g N/g VSS x d) are similar and within the range of the values reported in the literature (0.23 to 2.88 g N/g VSS x d). Therefore, the intrinsic kinetic parameter, q(max), can be obtained using attached-growth batch reactors, if the effectiveness factor, eta, is approximately equal to 1 and the bulk concentration of the rate-limiting substrate, C, is much higher than the half-velocity constant, K(S). The attached-growth batch reactor method is unique, because the biomass used in the batch tests is the same as that present in the parent reactor under investigation.