Application of constructed wetlands for wastewater treatment in tropical and subtropical regions (2000-2013)

Constructed wetlands(CWs) have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural(environmental)systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice,applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand(BOD) and total suspended solid(TSS) was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid(TSS)(91.3%), chemical oxygen demand(COD)(84.3%), and nitrogen(i.e.,80.7% for ammonium(NH)4-N, 80.8% for nitrate(NO)3-N, and 75.4% for total nitrogen(TN))as compared to other wetland systems. Vertical subsurface flow(VSSF) CWs removed TSS(84.9%), BOD(87.6%), and nitrogen(i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN)more efficiently than horizontal subsurface flow(HSSF) CWs, while HSSF CWs(69.8%)showed better total phosphorus(TP) removal compared to VSSF CWs(60.1%). Floating treatment wetlands(FTWs) showed comparable removal efficiencies for BOD(70.7%),NH4-N(63.6%), and TP(44.8%) to free water surface(FWS) CW systems.     

Modeling human exposures to air pollution control (APC) residues released from landfills in England and Wales

Human exposures to air pollution control (APC) residues released from 6 landfills were modeled and assessed. Following a qualitative risk characterisation, direct and indirect exposures were quantified. Site-specific air dispersion modeling was conducted for PM(10), PCDDs/PCDFs, Pb, Cd, As and Cr(VI) concentrations at the closest residential points of exposure for 4 landfill sites accepting, in total, 75% w/w of the APC residues disposed of in 2000-2001 (UK). Inhalation risks, assessed by reference to air quality standards at residential exposure points, were assessed as insignificant. Preliminary modeling suggested that indirect exposures from PCDDs/PCDFs at the 95th percentile level for the site where APC deposition rates were highest could potentially exceed the tolerable daily soil intake (TDSI) but this warrants further study given the model limitations. These results offer an initial screen of the significance of potential risks from APC disposal, which is of value in addressing concerns about the uncertainty of potential risks to human health from bulk APC disposal at strategic locations.     

The relative contribution of visual and auditory cues to environmental perception

This study assesses the relative dominance of vision and hearing in judgments of environments, and examines whether the sound sensitivity of the judge alters relative sensory dominance. Six sets of four composite (auditory-plus-visual) videotaped environmental displays were created from unisensory visual and auditory components with known levels of evoked affect. These displays, in a 2 (high, low) × 2 (high, low) Pleasure and/or Arousal format, were presented to 70 participants. The results indicate that visual cues dominate auditory cues in judgments of Pleasure, but that the degree of dominance is highly variable. Arousal judgments were not consistently related to visual or auditory cues. Sound sensitivity does not appear to influence the relative dominance of vision.     

Equilibrium studies for the sorption of lead from effluents using chitosan

The sorption of lead ions from aqueous solution onto chitosan has been studied. Equilibrium studies have been carried out to determine the capacity of chitosan for lead ions. The effects of solution pH and chitosan particle size on the sorption capacity have been studied.The experimental data were analyzed using three equilibrium isotherm correlations, namely, Langmuir, Freundlich and Redlich-Peterson equations. The linear correlation coefficients were determined for each isotherm and the Freundlich provided the best fit. In addition, error functions have been used to determine the alternative single component equilibrium isotherm parameters by non-linear regression due to the inherent bias in using the correlation coefficient from the linearization. This technique enables the "best fit" isotherm parameters to be used in the equilibrium equations for the sorption of lead ions on chitosan within the limits and assumptions of the various error analysis methods.     

Heavy Metal Contents and Magnetic Properties of Playground Dust in Hong Kong

This study examined the levels of seven heavy metals (namelyzinc, copper, cadmium, chromium, lead, manganese and iron) andtheir associations with magnetic properties in playground dustof Hong Kong. Results showed that the playground dust containedhigh concentrations of Zn (mean = 1883 g g^-1), Cu(mean = 143 g g^-1) and Cr (mean = 263 g g^-1).Qualitative examination of dust samples under microscope indicated local traffic as one of the important pollutant sources. Magnetic measurements indicated that these anthropogenicpollutants mainly consisted of coarse-grained multidomain (MD) ferrimagnetic minerals. Superparamagnetic (SP), stable single domain (SSD) ferrimagnetic grains and non-ferrimagnetic mineralswere present in relatively small amounts. Significant correlations between heavy metals and various magnetic parametersindicated a strong affinity of heavy metals to magnetic minerals hence pointed out the potential of magnetic properties for simpleand rapid proxy indications of heavy metal pollution in playground dust.     

An investigation on biological stability of product water generated by lab-scale and pilot-scale distillation systems

Material Disposal Area G is the primary low-levelradioactive waste disposal site at Los Alamos NationalLaboratory, New Mexico, and is adjacent to Pueblo of SanIldefonso lands. Pueblo residents and Los Alamos scientists areconcerned about radiological doses resulting from uptake of AreaG radionuclides by mule deer (Odocoileus hemionus) andRocky Mountain elk (Cervus elaphus), then consumption ofdeer and elk meat by humans. Tissue samples were collected fromdeer and elk accidentally killed near Area G and were analyzedfor ³H, ⁹⁰Sr, total U, ²³⁸Pu, ^{239, 240}Pu,²⁴¹Am, and ¹³⁷Cs. These data were used to estimatehuman doses based on meat consumption of 23 kg y^-1. Humandoses were also modeled using RESRAD, and dose rates to deer andelk were estimated with a screening model. Dose estimates tohumans from tissue consumption were 2.9 × 10^-3 mSv y^-1and 1.6 × 10^-3 mSv y^-1 from deer and elk, respectively,and RESRAD dose estimates were of the same order of magnitude. Estimated dose rates to deer and elk were 2.1 × 10^-4 mGyd^-1 and 4.7 × 10^-4 mGy d^-1, respectively. Allestimated doses were significantly less than established exposurelimits or guidelines.     

The relationship between recruitment processes, familiarity, trust, perceived risk and safety

Introduction and Method

Participants′ perceptions of the safety-related aspects of their organization′s recruitment processes were examined, as were their perceptions of safety aspects associated with new recruits.

Results

One hundred and fifty-four professional fire fighters indicated the trust they held in the safety-related aspects of their organizations′ selection and pre-start training. Perceived trust in pre-start training was negatively correlated (r = -.24, p < .01) with the risk associated with new recruits, and positively correlated (r = .50, p < .01) with ratings of trust in recruits to immediately work safely. Furthermore, trust in recruits to immediately work safely was negatively correlated (r = -.21, p < .01) with crews′ safety behavior toward recruits.

Conclusions

These results are interpreted as particularly dangerous for workers, as new recruits lack familiarity with aspects of their new workplace that cannot be addressed by either selection or pre-start training, making them a risk.

Impact on Industry

Organizations should actively identify new recruits, and encourage existing team members not to immediately trust new recruits to work safely.     

Occupational embeddedness and job performance

While researchers have recently focused their attention on organizational embeddedness, occupational embeddedness has received little theoretical and empirical attention. Using multisource data on 162 employees in multiple jobs and organizations, we found that occupational embeddedness is positively related to both task performance and creativity and is negatively related to counterproductive work behavior, even after controlling for the effects of organizational embeddedness. In addition, we found that trait affect moderated the relationships of occupational embeddedness to job performance. Occupational embeddedness was more strongly related to counterproductive work behavior when trait negative affect was high, while occupational embeddedness was more strongly related to both citizenship behavior and creativity when trait positive affect was high. Results also indicated that the various components of occupational embeddedness had different effects on job outcomes. Fit had a strong positive effect on core task performance, links had a positive effect on creativity, and sacrifice had a small positive effect on citizenship behavior. The article concludes with a discussion of implications for future research and management practice. Copyright © 2009 John Wiley & Sons, Ltd.     

Catalytic Activity of Biomorphic α-MoO(3) in the Degradation of Methyl Violet Dye

A network of fibers comprising orthorhombic molybdenum trioxide (α-MoO(3)) crystals were synthesized using paper as template via a biomorphic approach. The template was completely removed by annealing the sample at 600°C for 5?min. Monoclinic MoO(3) was formed and consequently converted into orthorhombic α-MoO(3) after prolonged annealing. Three milligrams of the biomorphic α-MoO(3) could degrade up to 90% of a methyl violet aqueous solution with a concentration of 20?mg/L under normal visible light. The size of the α-MoO(3) grains and the porosity of the biomorphic sample affected catalytic performance.