Qualitatively and quantitatively assessing the aggregation ability of sludge during aerobic granulation process combined XDLVO theory with physicochemical properties

Inexact mechanism of aerobic granulation still impedes optimization and application of aerobic granules. In this study, the extended Derjaguin, Landau, Verwey, and Overbeek(XDLVO) theory and physicochemical properties were combined to assess the aggregation ability of sludge during aerobic granulation process qualitatively and quantitatively. Results show that relative hydrophobicity of sludge and polysaccharide content of extracellular polymeric substances(EPS) increased, while electronegativity of sludge decreased during acclimation phase. After 20 days' acclimation, small granules began to form due to high aggregation ability of sludge. Since then, coexisted flocs and granules possessed distinct physicochemical properties during granulation and maturation phase. The relative hydrophobicity decreased while electronegativity increased for flocs, whereas that for granules presented reverse trend. Through analyzing the interaction energy using the XDLVO theory, small granules tended to self-grow rather than self-aggregate or attach of flocs due to poor aggregation ability between flocs and granules during the granulation phase. Besides, remaining flocs were unlikely to self-aggregate owing to poor aggregation ability, low hydrophobicity and high electronegativity.     

RETRACTED ARTICLE: Consequences of health risk assessment of wastewater irrigation in Pakistan

Statement of Retraction

We, the Editors and Publisher of Toxicological & Environmental Chemistry, have retracted the following article:

Maria Sabeen, Qaisar Mahmood, Abdol Ghaffar Ebadi, Zulfiqar Ahmad Bhatti, Faridullah, Muhammad Irshad, Allauddin Kakar, Muhammad Bilal, Hafiz Muhammad Arshad and Naeem Shahid, ‘Consequences of health risk assessment of wastewater irrigation in Pakistan Israel Affairs’, Toxicological & Environmental Chemistry, 2019, DOI: 10.1080/02772248.2019.1619335

The article is retracted due to the oversights that were made during peer review process that resulted in the article being published online in error. Further review from independent reviewers was sought. This confirmed that the central findings and methodology of the study in question are unreliable and therefore unsuitable for publication.

We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions.

The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as “Retracted”.     

Routinization of job context and job content as related to employees' quality of working life: A study of Canadian nurses

The literature on routinization of work is both ambiguous and equivocal when its impact on quality of working life is considered. The classical management literature suggests that routinization of work has a positive influence on individual performance and by implication on the quality of working life resulting from the overall prosperity generated. However, more recent literature on job characteristics and job design argues that routinization of work has a negative impact on individual performance as it suppresses creative expression on the job. This paper suggests that these mixed findings are due to an inadequate theoretical grasp of the concept of routinization and presents empirical evidence which attempts to clarify the ambiguity. Data were collected from 1148 nurses working in anglophone hospitals in the greater Montreal area in the form of a field survey questionnaire. The results indicated that nurses who worked routine shifts perceived higher levels of quality of working life compared to those on non-routine shifts. The results also indicated that nurses who experienced high routinization in job content perceived lower levels of quality of working life compared to those nurses who experienced low routinization in job content. Implications of these findings for future research are discussed.     

Shiftwork and department-type related to job stress,work attitudes and behavioral intentions: A study of nurses

The present study examined the relationship of shiftwork and department-type with employees' job stress, stressors, work attitudes and behavioral intention. Data were collected by means of a structured questionnaire from nurses (N = 1148) working in eight hospitals in a large, metropolitan city in eastern Canada. One-way ANOVA, MANOVA and two-way ANOVA were used to analyze data. Results generally support the prediction that nurses working on fixed shifts were better off than nurses working on rotating shifts in terms of the dependent variables of the present study. The prediction that nurses working in non-intensive care departments were better off than nurses working in intensive care departments received mixed support at best. A few interaction effects of shiftwork × department-type on dependent variables were also noted. The impact of socio-demographic variables — age, marital status, cultural background (English- versus French-speaking) — on the above relationships were also analyzed. Results are discussed in light of the previous empirical evidence on shiftwork and department-type.     

STATUS AND PROSPECTS OF KAREZ IRRIGATION1

ABSTRACT: The karez is a traditional irrigation water source, consisting of hand-dug horizontal wells, that is still used in parts of South Asia, the Middle East, and North Africa. This paper describes the construction, management, and current problems of karez irrigation systems based on investigations conducted in Baluchistan Province, Pakistan. While karezes have served irrigation needs well in the past, they are now threatened by high costs of labor for construction and maintenance, and by the encroachment of tubewells which lower the water tables on which the karez systems depend. Possible methods for improving karez performance and needs for research are discussed.     

VALUING IRRIGATION WATER IN PUNJAB PROVINCE,PAKISTAN: A LINEAR PROGRAMMING APPROACH1

ABSTRACT: Linear programming models of a representative farm in a district of Pakistan's Punjab Province are formulated for the purpose of estimating the value of irrigation water. The models provide for choices among several irrigation levels for each potential crop. Solutions of the model for several water supply situations provide the basis for approximating the total, average, and marginal values of irrigation water. Prices for important crops in Pakistan are controlled at levels below their levels elsewhere in the world, so models are specified for both financial (domestic price) and economic (world price) scenarios. The value of water to society (its economic value) is high relative to the costs of some generally available water-augmenting investments, while financial values, which measure water management and allocation incentives faced by farmers, are less than the corresponding economic values. At current water supply levels, incremental returns to added water estimated from the economic model would justify investments in water-saving or water-augmenting technologies, while such a decision would be barely attractive assuming financial prices. While present government commodity price policies may serve to protect low-income and non-farm members of the population, they also inhibit farmer investments to increase the productivity of scarce irrigation water.     

Mimic Enzyme Based Cellulose Nanocrystals/PVA Nanocomposite Membranes for Enrichment of Biogas as a Natural Gas Substitute

Journal of Polymers and the Environment - Nanocomposite membranes promoted by mimic enzyme was developed and optimized for biogas upgrading at moderately high pressure applications up to...     

Measurement of metal bioaccessibility in vegetables to improve human exposure assessments: field study of soil–plant–atmosphere transfers in urban areas,South China

The quality of cultivated consumed vegetables in relation to environmental pollution is a crucial issue for urban and peri-urban areas, which host the majority of people at the global scale. In order to evaluate the fate of metals in urban soil–plant–atmosphere systems and their consequences on human exposure, a field study was conducted at two different sites near a waste incinerator (site A) and a highway (site B). Metal concentrations were measured in the soil, settled atmospheric particulate matter (PM) and vegetables. A risk assessment was performed using both total and bioaccessible metal concentrations in vegetables. Total metal concentrations in PM were (mg kg^?1): (site A) 417 Cr, 354 Cu, 931 Zn, 6.3 Cd and 168 Pb; (site B) 145 Cr, 444 Cu, 3289 Zn, 2.9 Cd and 396 Pb. Several total soil Cd and Pb concentrations exceeded China’s Environmental Quality Standards. At both sites, there was significant metal enrichment from the atmosphere to the leafy vegetables (correlation between Pb concentrations in PM and leaves: r = 0.52, p < 0.05) which depended on the plant species. Total Cr, Cd and Pb concentrations in vegetables were therefore above or just under the maximum limit levels for foodstuffs according to Chinese and European Commission regulations. High metal bioaccessibility in the vegetables (60–79 %, with maximum value for Cd) was also observed. The bioaccessible hazard index was only above 1 for site B, due to moderate Pb and Cd pollution from the highway. In contrast, site A was considered as relatively safe for urban agriculture.     

PBDEs and PCDD/Fs in surface soil taken from the Taizhou e-waste recycling area,China

The emerging issue of electronic wastes (e-waste) and the associated environmental problems has gained considerable attention from the scientific community in recent decades. In the present study, the levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the surface soil obtained from the Taizhou e-waste recycling area of China were investigated. Also the correlation among these chemicals and previously published data of heavy metals, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls was analysed. We determined that the pollution levels of eight PBDEs congeners were serious, ranging from 27.9 to 3128.4 μg/kg. The concentration of PCDD/Fs was in the range of 218.3–3122.2 pg/g with a mean value of 659.5 pg/g. The PBDEs were not well-correlated with organic pollutants (PAHs and PCBs) in soil, whereas PCDD/Fs exhibited a significant positive correlation with the PCBs. The higher levels of persistent organic pollutants may pose potential adverse effects to soil quality and human beings and needs to be properly managed and remediated.