Removal of toluene vapour from air stream using a biofilter packed with polyurethane foam

Biodegradation of toluene vapour was investigated for 168 days in a polyurethane packed biofilter inoculated with a mixed microbial population. Biofilter consisted of five square cross-section modular units each of size 0.16 m × 0.16 m × 0.20 m and filled with the polyurethane foam cubes up to a height of 0.15 m. Inlet concentration of toluene was varied from 0.04 to 2.5 g m^?3 and the volumetric flow rate of toluene loaded air from 0.06 to 0.90 m³ h^?1.Depending upon initial loading rates, removal efficiency ranging from 68.2 to 99.9% and elimination capacity ranging from 10.85 to 90.48 g h^?1 m^?3 were observed during steady state operations. More than 90% removal efficiency was observed up to an inlet loading rate of 76.3 g h^?1 m^?3. High carbon recovery (>90%) indicated effective biodegradation in the bed. Low variation of pH (7.2–8.8) and pressure drop (45.8–76.3 Pa) was observed. The stability of the biomass was evident from the fast response of the biofilter to shutdown and restartup.     

Characterization of heavy metals in fly ash from municipal solid waste incinerators in Shanghai

This study aims to develop a methodology for analysis of characteristics of heavy metals in MSWI fly ash. It performed analysis of composition of heavy metals, leaching toxicity, leaching behavior as a function of pH, specification distribution and corresponding mineral components of residue derived from each step of the sequential extraction. It is found that content of heavy metals follows the sequence of Zn > Pb > Cu > Cr > As > Ni > Cd approximately Hg in both plants, and that total heavy metals account for less than 1% by mass of fly ash. Major hazardous heavy metals in fly ash are As, Cd, Hg, Pb and Zn, whose leaching ratios exceed the limit value described in hazardous waste identification standard. Measured leaching results of Cu, Pb and Zn are essentially consistent with the simulated results at pH between 0 and 13. Content of calcium-silicates, alumino-silicates and glass phases in residue derived from sequential extraction procedure increases steadily from the first step to the fifth step of the sequential extraction procedure. Cu, As, Cr, Hg, Cd, and Ni, relatively stable under strong basic conditions, can be leached out under strong acidic conditions, while Zn and Pb tend to be leached out under both strong acidic and basic conditions.     

Association between safety leading indicators and safety climate levels

ObjectivesThe aim of this study was to evaluate the association of leading indicators for occupational health and safety, particularly safety inspections and non-compliances, with safety climate levels.MethodsNordic Occupational Safety Climate Assessment Questionnaire was employed to evaluate safety climate in cross-sectional design. The geographically diverse population of the inspection body made it possible to conduct the survey across 10 provinces in Iran. 89 completed questionnaires were obtained with a response rate of 47%. Except for management safety justice, the internal consistency of other six dimensions was found to be acceptable (α ≥ 0.7).ResultsMean scores of dimensions ranged from 3.50 in trust in the efficacy of safety systems (SD = 0.38) to 2.98 in workers' safety priority and risk non-acceptance (SD = 0.47). Tukey HSD tests indicated a statistically significant difference of mean scores among groups undergoing different number of safety inspections and those receiving different number of non-compliances (p < 0.05), with no significant differences based on safety training man-hours and sessions (p > 0.05). Spearman's rank-order correlation showed no relationship between work experience and number of non-compliances (correlation coefficient = − 0.04, p > 0.05) and between safety training man-hours and number of non-compliances (correlation coefficient = − 0.15, p > 0.05).ConclusionsOur results indicate that safety climate levels are influenced by number of safety inspections and the resultant non-compliances.Practical applicationsFindings suggest that safety non-compliances detected as a result of conducting safety inspections could be used to monitor the safety climate state. Establishing plans to conduct scheduled safety inspections and recording findings in the form of safety non-compliance and monitoring their trend could be used to monitor levels of safety climate.     

Degradation of Rhodamine B by an electrochemical ozone generating system consist of a Ti anode coated with nanocomposite of Sn–Sb–Ni oxide

An ozonation process was performed using a recycled electrochemical ozone generator system. A titanium based electrode, coated with nanocomposite of Sn–Sb–Ni was applied as anode in a laboratory-made electrochemical reactor. A constant flow rate of 192 mg/h of generated ozone was entered to an ozonation reactor to contact with a typical target pollutant, i.e., Rhodamine B (Rh.B) molecules in aqueous solution. Four operational parameters such as: initial dye concentration, pH, temperature and the contact time were evaluated for the ozonation process. Experimental findings revealed that for a solution of 8 mg/L of the dye, the degradation efficiency could reach to 99.5% after 30 min at pH 3.7 and temperature of 45 °C as the optimum conditions. Kinetic studies showed that a second order equation can describe the ozonation adequately well under different temperatures. Also, considering to the importance of process simulation, a three-layered feed forward back propagation artificial neural network model was developed. Sensitivity analysis indicated order of the operational parameter's relative importance on the model output as: time ≫ pH > Rh . B initial concentration > temperature.     

Fatal and serious injuries related to vulnerable road users in Canada

IntroductionThe goals of this study were to analyze possible trends of fatal and serious injuries related to vulnerable road users in Canada (pedestrians, cyclists and motorcyclists) from 1990 to 2012 and the role of alcohol and drugs in these cases. Drugs have rarely been documented with respect to vulnerable road users.MethodThe Traffic Injury Research Foundation's National Fatality and Serious Injury Databases and the Public Health Agency of Canada's Canadian Hospitals Injury Reporting and Prevention Program databases were used. Numbers and rates of fatalities and serious injuries among vulnerable road users were analyzed and regression models were used to assess changes over time.ResultsThe analyses show that while the absolute number of fatalities and the rate per 100,000 population among vulnerable road users may be decreasing, no such trends are apparent when looking at the proportions of these road user fatalities out of all motor-vehicle fatalities. The trend for the proportion of motorcyclist fatalities is significantly increasing (coef. = 0.16, p < 0.001). The elderly (76 years or older) are overrepresented among pedestrian fatalities, and serious injuries (they represent 18.5% of all pedestrian fatalities but only 5.8% of the population), while those 15 years or younger are overrepresented among cyclists (they represent 23.3% of cyclist fatalities but 19.5% of the population), and those 16 to 25 years old are overrepresented among motorcyclists (27.2% of motorcyclists fatalities and 13.6% of population). Alcohol and drug use among fatally injured vulnerable road users were significant problems, especially among pedestrians. Among fatally injured pedestrians tested for alcohol and drugs, 39.7% and 43.4% tested positive, respectively.ConclusionsWith the promotion of walking and cycling as forms of exercise and the popularity of motorcycling, the safety of vulnerable road users is an important issue. The results corroborate previous research and extend our understanding about the influence of alcohol and drugs in vulnerable road user injuries.Practical applicationsThese findings can help better inform prevention and mitigation initiatives for vulnerable road users.     

Preparation of iodine doped titanium dioxide to photodegrade aqueous bisphenol A under visible light

Highly photoactive iodine-doped titanium dioxide (I-doped TiO₂) photocatalysts were synthesized to degrade aqueous bisphenol A (BPA) under irradiation by visible light and sunlight. The band gap energies of TiO₂ and I-doped TiO₂ (I/Ti mole ratio = 0.5%) were 3.01 and 3.04, and the BPA photodegradation rate constants were 1.61, and 5.11 h⁻¹, respectively. The most probable reaction mechanism was proposed to involve IO₄⁻ and IO₃⁻ as electron acceptors that generate an inductive effect, increasing the photocatalytic efficiency of TiO₂. Results indicated that I-doped TiO₂ not only acted favorably as a photocatalyst, but also exhibited considerable mineralization effects. In addition, a recycling test after ten experiments demonstrated the stability and reusability of the photocatalyst.     

The electrocoagulation/flotation study: The removal of heavy metals from the waste fountain solution

The objective of this study was to investigate the possibility of heavy metals (copper, zinc and nickel) removal from the waste fountain solution by the electrocoagulation/flotation (ECF) treatment. After the printing process, the fountain solution changes its composition due to direct contact with different printing materials (plates, inks, etc.) and becomes enriched with metals. The effect of operational parameters, such as electrode materials and combinations, current density, interelectrode distance and operating time, was studied. Also, response surface methodology (RSM) was applied to evaluate the effect of main operational variables and to get a balanced removal efficiency of metals from waste fountain solution by ECF treatment. The iron/iron electrode combination yields a higher percentage of copper and zinc removal efficiency (>95% and >80%, respectively), while for nickel the aluminum/iron and iron/aluminum electrode combinations (>95 and >85%, respectively) proved to be more successful. The optimum interelectrode distance was 1.0 cm (for copper) and 1.5 cm (for zinc and nickel) for all current densities. Heavy metal removal efficiency increases with the increase of electrolysis time for all electrode combinations. Also, the increase of current density improves the ECF removal efficiency. Based on the results obtained through RSM, the optimized parameters for the ECF waste fountain solution treatment for metal removal were identified as: Fe(−)/Al(+) electrode with interelectrode distance of 1.5 cm, operating time of 60 min and current density of 8 mA cm⁻². Overall, the ECF treatment was proven very efficient in the removal of heavy metals from the waste fountain solution under optimum conditions.     

pH-conditioning for simultaneous removal of arsenic and iron ions from groundwater

The effects of some commonly used pH conditioners, viz., lime, banana ash, the carbonate and the bicarbonate of sodium and potassium and their binary mixture, on simultaneous removal of arsenic and iron ions from water have been studied. KHCO₃ has been found to be the most suitable pH conditioner for the purpose. About 80 mg/L KHCO₃ can remove both arsenate and iron ions from initial 250 μg/L and 20 mg/L to below their respective guideline values of the WHO for drinking water, retaining the final pH in the acceptable range for drinking. The simultaneous removal of arsenate and iron by the pH-conditioners decreases in the order: Lime > KHCO₃ > NaHCO₃ > K₂CO₃ > Na₂CO₃ > ash. However, lime requires post-treatment correction of highly alkaline pH. The arsenate ion is removed predominantly through goethite or ferrihydrite in the presence of the bicarbonates and through ferric hydroxide in the presence of the more alkaline pH-conditioners. KHCO₃ is more advantageous over the more basic substances including NaHCO₃, because with it, one not only needs the smallest dose but also can avoid careful adjustment of the dose for regulating the initial and the final pH. The paper clearly demonstrates the potential of KHCO₃ to substitute the currently used pH-conditioners, viz., ash, lime and NaHCO₃ for simultaneous removal of arsenate and iron ions.     

Evaluation of membrane bioreactor for hypersaline oily wastewater treatment

Produced water is a significant waste stream generated in association with oil and gas production. It contains high concentrations of hydrocarbon constituents and different salts. In this study, a membrane sequencing batch reactor (MSBR) was used to treat synthetic and real produced water. The MSBR was evaluated in terms of biodegradation of hydrocarbons in the synthetic produced water with various organic loading rates (OLR) (0.281, 0.563, 1.124, 2.248, and 3.372 kg COD/(m³ day)), cycle time (12, 24, and 48 h), and membrane performance. The effects of salt concentrations at different total dissolved solids (TDS) (35,000, 50,000, 100,000, 150,000, 200,000, and 250,000 mg/L) on biological treatment of the pollutants in the synthetic and real wastewater were studied. At an OLR of 1.124 kg COD/(m³ day), an HRT of 48 h and TDS of 35,000 mg/L, removal efficiencies of 97.5%, 97.2%, and 98.9% of COD, total organic carbon (TOC), and oil and grease (O&G), respectively were achieved. For the real produced water, removal rates of 86.2%, 90.8%, and 90% were obtained for the same conditions. However, with increasing salt content, the COD-removal efficiencies of the synthetic and real produced water were reduced to 90.4% and 17.7%, respectively at the highest TDS.     

Evaluation of an in-vehicle monitoring system (IVMS) to reduce risky driving behaviors in commercial drivers: Comparison of in-cab warning lights and supervisory coaching with videos of driving behavior

ProblemRoadway incidents are the leading cause of work-related death in the United States.MethodsThe objective of this research was to evaluate whether two types of feedback from a commercially available in-vehicle monitoring system (IVMS) would reduce the incidence of risky driving behaviors in drivers from two companies. IVMS were installed in 315 vehicles representing the industries of local truck transportation and oil and gas support operations, and data were collected over an approximate two-year period in intervention and control groups. In one period, intervention group drivers were given feedback from in-cab warning lights from an IVMS that indicated occurrence of harsh vehicle maneuvers. In another period, intervention group drivers viewed video recordings of their risky driving behaviors with supervisors, and were coached by supervisors on safe driving practices.ResultsRisky driving behaviors declined significantly more during the period with coaching plus instant feedback with lights in comparison to the period with lights-only feedback (ORadj = 0.61 95% CI 0.43–0.86; Holm-adjusted p = 0.035) and the control group (ORadj = 0.52 95% CI 0.33–0.82; Holm-adjusted p = 0.032). Lights-only feedback was not found to be significantly different than the control group's decline from baseline (ORadj = 0.86 95% CI 0.51–1.43; Holm-adjusted p > 0.05).ConclusionsThe largest decline in the rate of risky driving behaviors occurred when feedback included both supervisory coaching and lights.Practical applicationsSupervisory coaching is an effective form of feedback to improve driving habits in the workplace. The potential advantages and limitations of this IVMS-based intervention program are discussed.     

Ion exchange membrane-assisted electro-activation of aqueous solutions: Effect of the operating parameters on solutions properties and system electric resistance

The properties of electro-activated (EA) aqueous solutions as well as the dynamics of their changes were considered in the current study using aqueous solutions of NaCl and NaHCO₃. The concentrations of the salt solutions were 0.5, 0.25, 0.125 and 0.05 M. The tests were performed at the DC current densities of 25, 37.5, and 50 Å/m². The electro-activation reactor consisted of three individual cells assembled together and separated by anion-exchange (AEM) and cation-exchange (CEM) membranes. During the experiments, four configurations of the membrane placements and solutions concentrations were studied. The obtained results showed the dynamics of the electro-activation process that allows obtaining electro-activated solutions with targeted properties such as pH and oxydo-reduction potential (ORP). It was possible to obtain electro-activated solutions at the anodic side (acid anolyte) with pH of 3.0, 3.5, and 4.0 and ORP of +1100 ± 15 mV when NaCl solution was used as electrolyte. Furthermore, several types of electro-activated solutions with high redox potential (ORP = +921 ± 12 mV) and neutral pH (6.48 ± 0.05) were obtained on the anode side when sodium carbonate was used. At the same time, two types of solutions, one with acid pH (2.14 ± 0.14) and the other one with alkaline pH (10.46 ± 0.03) with ORP = +689 ± 10 and 110 ± 21 mV, respectively, were obtained in the central compartment which considered as electro-activated solutions obtained by means of noncontact electro-activation.     

Application of Modified Carbon Anodes in Microbial Fuel Cells

The effect of different carbon anodes was examined in a new design of single chambered microbial fuel cell (SCMFC). The new cell design used a low-cost hydrophilic membrane to replace costly proton exchange membranes and carbon felt and a range of carbon and modified carbon anodes were investigated. The fuel for the SCMFC was brewery wastewater which was diluted with domestic wastewater and the presented microflora acts as a source of electro-active bacteria. The membrane acts as a separator between the anode chamber and an air cathode and allows the transfer of ions based on the wastewater's natural conductivity. The air cathode was carbon black (Ketjen Black EC 300J) which was deposited (1 mg cm⁻² concentration) directly onto the surface of the separator (one side of the membrane). Steady state polarization demonstrated maximum power densities of up to 30 mW m⁻² and a steady state power density of 20 mW cm⁻² at a current density of 110 mA m⁻² was achieved. The best performing anodes were made from carbon modified with quinone/quinoid groups. With unmodified graphite felt (the control anode material) as anode, the maximal power density obtained was 9.5 mW m⁻².     

Using a cluster randomized controlled trial to determine the effects of intervention of battery and hardwired smoke alarms in New South Wales,Australia: Home fire safety checks pilot program

IntroductionIn 2014, Fire & Rescue New South Wales piloted the delivery of its home fire safety checks program (HFSC) aimed at engaging and educating targeted top “at risk” groups to prevent and prepare for fire. This pilot study aimed to assess the effectiveness of smoke alarms using a cluster randomized controlled trial.MethodsSurvey questionnaires were distributed to the households that had participated in the HFSC program (intervention group). A separate survey questionnaire was distributed to the control group that was identified with similar characteristics to the intervention group in the same suburb. To adjust for potential clustering effects, generalized estimation equations with a log link were used.ResultsMultivariable analyses revealed that battery and hardwired smoking alarm usage increased by 9% and 3% respectively among the intervention group compared to the control group. Females were more likely to install battery smoke alarms than males. Respondents who possessed a certificate or diploma (AOR = 1.31, 95% CI 1.00–1.70, P = 0.047) and those who were educated up to years 8–12 (AOR = 1.32, 95% CI 1.06–1.64, P = 0.012) were significantly more likely to install battery smoke alarms than those who completed bachelor degrees. Conversely, holders of a certificate or diploma and people who were educated up to years 8–12 were 31% (AOR = 0.69, 95% CI 0.52–0.93, P = 0.014) and 24% (AOR = 0.76, 95% CI 0.60–0.95, P = 0.015) significantly less likely to install a hardwired smoke alarm compared to those who completed bachelor degrees.ConclusionsThis pilot study provided evidence of the benefit of the HFSC in New South Wales. Practical Applications: Fire safety intervention programs, like HFSC, need to be targeted to male adults with lower level of schooling even when they are aware of their risks.     

Raising the speed limit from 75 to 80 mph on Utah rural interstates: Effects on vehicle speeds and speed variance

IntroductionIn November 2010 and October 2013, Utah increased speed limits on sections of rural interstates from 75 to 80 mph. Effects on vehicle speeds and speed variance were examined.MethodsSpeeds were measured in May 2010 and May 2014 within the new 80 mph zones, and at a nearby spillover site and at more distant control sites where speed limits remained 75 mph. Log-linear regression models estimated percentage changes in speed variance and mean speeds for passenger vehicles and large trucks associated with the speed limit increase. Logistic regression models estimated effects on the probability of passenger vehicles exceeding 80, 85, or 90 mph and large trucks exceeding 80 mph.ResultsWithin the 80 mph zones and at the spillover location in 2014, mean passenger vehicle speeds were significantly higher (4.1% and 3.5%, respectively), as were the probabilities that passenger vehicles exceeded 80 mph (122.3% and 88.5%, respectively), than would have been expected without the speed limit increase. Probabilities that passenger vehicles exceeded 85 and 90 mph were non-significantly higher than expected within the 80 mph zones. For large trucks, the mean speed and probability of exceeding 80 mph were higher than expected within the 80 mph zones. Only the increase in mean speed was significant. Raising the speed limit was associated with non-significant increases in speed variance.ConclusionsThe study adds to the wealth of evidence that increasing speed limits leads to higher travel speeds and an increased probability of exceeding the new speed limit. Results moreover contradict the claim that increasing speed limits reduces speed variance.Practical applicationsAlthough the estimated increases in mean vehicle speeds may appear modest, prior research suggests such increases would be associated with substantial increases in fatal or injury crashes. This should be considered by lawmakers considering increasing speed limits.     

Risk factors associated with sick leave due to work-related injuries in Dutch farmers: an exploratory case-control study

Using data from an insurance company, the occurrence of sick leave among Dutch farmers due to work-related injuries, and the epidemiological risk factors were investigated. In this case-control study the cases had filed a sick leave claim for work-related injury from 1998–2001 and the controls had not filed any claim in this period. Most (74%) of all injuries were work-related. The most frequent types of injury (63%) were bruises, sprains/strains and fractures. Multivariable logistic regression analysis showed that farmers working in dairy farming (OR=2.6) or pig husbandry (OR=2.7), older farmers (OR=1.48 per 10 years) and smokers (OR=1.7) were at increased risk. Within dairy farming, a significant factor was contact with cows (OR=1.7 per 500 h); within pig husbandry, working > 60 h per week was a significant factor (OR=2.2). The population attributable risk was 24% for elimination of smoking, 23% for halving the number of hours' contact with cows in dairy farming and 18% for elimination of a working duration > 60 h per week in pig husbandry. Effective measures to prevent sick leave might be raising awareness that older farmers and smokers are at increased risk, and a focus on the risks of working with animals.     

Boron removal from produced water using electrocoagulation

Produced water is the largest wastestream of oil and gas exploration but its chemical composition hinders its beneficial use. Effective treatment and reuse of produced water can mitigate scarcity of fresh water, especially in arid areas. Presence of inorganic compounds such as boron in produced water renders its beneficial use difficult. In this study, boron removal from produced water was investigated. Synthetic wastewater was prepared simulating the range of boron concentrations in produced water. Four operating parameters pH (3–11), charge loading (1200–3600 Ah/m³), contact time (15–90 min) and concentration (10–30 mg/L) were selected and their optimum conditions investigated. The obtained optimum conditions were applied to treat real produced water. Residual boron concentration of 0.3 mg/L was obtained from initial boron concentration of 15 mg/L in real produced water at optimum conditions of pH 7, charge loading 2400 Ah/m³ and contact time 90 min. Boron adsorption could be represented by Langmuir and Freundlich isotherm models. Electrocoagulation can be used for the effective removal of boron from produced water.     

Simultaneous photocatalytic treatment of Cr(VI), Ni(II) and SDBS in aqueous solutions: Evaluation of removal efficiency and energy consumption

Simultaneous photocatalytic reduction of poisonous Cr(VI) and Ni(II) ions, coupled with photocatalytic oxidation of sodium dodecyl benzene sulfonate (SDBS) were studied with a trace amount of commercial titania nanoparticles and by means of a direct-photo-irradiation reactor. The co-presence of metal ions and SDBS causes metal ions reduction as well as SDBS oxidation to enhance and energy efficiency to improve. XRD, XPS and FTIR analysis were used to characterize TiO₂ particles before and after usage with the aim of evaluating the mechanism of reactions. The effect of major operating parameters, pH and temperature, was investigated. Under conditions of [Cr(VI)]₀ = [Ni(II)]₀ = 5 mg/L, [SDBS]₀ = 10 mg/L, [TiO₂] = 40 mg/L, pH 6 and T = 35 °C; the removal efficiencies of 55.4%, 71.2% and 57.2% were obtained, respectively, for Cr(VI) and Ni(II) reduction, as well as for SDBS oxidation, after 110 min operation. The relevant kinetic model jointed with the Arrhenius equation was introduced. Pseudo-first-order reactions are relevant. Energy consumption (electrical and thermal) evaluations revealed that operations at higher temperatures provide significant cost reduction. Meantime, a criterion was proposed for a consistent assessment of this kind of processes.     

Explosion behavior of n-alkane/nitrous oxide mixtures

The explosion properties of alkane/nitrous oxide mixtures were investigated and were compared with those of the corresponding alkane/oxygen and alkane/air mixtures. The explosion properties were characterized by three parameters: the explosion limit, explosion pressure, and deflagration index. For the same alkane, the order of the lower explosion limits (LELs) of the mixtures was found to be alkane/oxygen ≈ alkane/air > alkane/nitrous oxide. In addition, the mixtures containing nitrous oxide tended to exhibit higher explosion pressures than the corresponding mixtures containing oxygen under fuel-lean conditions. The Burgess–Wheeler law was also observed to hold for the mixtures containing nitrous oxide.