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Sustainable management of leachate produced from the dumpsite is one of the major concerns in developing countries Aquatic plants such as duckweed have the potential to remove pollutants from wastewater which can also be cost-effective and feasible options for leachate treatment. Therefore, the objective of our present study was to examine the growth and nutrient removal efficiency of duckweed (Lemna minor) on leachate. Three tests were performed each by growing lemna minor on synthetic leachate under controlled conditions and on dumpsite leachate under natural conditions. During each test, duckweed was grown in 300 ml plastic containers with a surface area of 25.8 cm2. About 60 mg of fresh mass of duckweed was grown on 250 ml leachate at an internal depth of 9.5 cm. Results revealed that, in comparison to synthetic leachate, duckweed removed Chemical Oxygen Demand (COD), nitrogen (N), and phosphorous (P) more efficiently from dumpsite leachate under natural climatic conditions. However, the amounts of N and P absorbed into duckweed body mass were about 16% and 35% respectively more at synthetic leachate under controlled conditions. Maximum growth rate of duckweed (7.03 g m-2 day-1) was also observed for synthetic leachate in comparison to the growth rate of 4.87 g m-2 day-1 at dumpsite leachate. Results of this study provide a useful interpretation of duckweed growth and nutrient removal dynamics from leachate under natural and laboratory conditions.

The heavy metals, such as Cr(VI), Pb(II) and Cd(II), in aqueous solutions are toxic even at trace levels and have caused adverse health impacts on human beings. Hence the removal of these heavy metals from the aqueous environment is important to protect biodiversity, hydrosphere ecosystems, and human beings. In this study, magnetic Nickel-Ferrite Nanoparticles (NFNs) were synthesized by co-precipitation method and characterized using X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Field Emission Scanning Electronic Microscopy (FE-SEM) techniques in order to confirm the crystalline structure, composition and morphology of the NFN’s, these were then used as adsorbent for the removal of Cr(VI), Pb(II) and Cd(II) from wastewater. The adsorption parameters under study were pH, dose and contact time. The values for optimum removal through batch-adsorption were investigated at different parameters (pH 3–7, dose: 10, 20, 30, 40 and 50 mg and contact time: 30, 60, 90, and 120 min). Removal efficiencies of Cr(VI), Pb(II) and Cd(II) were obtained 89%, 79% and 87% respectively under optimal conditions. It was found that the kinetics followed the pseudo second order model for the removal of heavy metals using Nickel ferrite nanoparticles.

Pakistan, an agricultural country, raises 146.5 million commercial and domestic poultry birds, which generate around 544,831 tons of waste per year. This waste finds its final disposal in agricultural land as soil fertilizer or disposal site amendment. The usage of poultry litter for this purpose is uncontrolled, which results in environmental degradation such as emission of greenhouse gases, e.g., methane. However, alternative options such as thermochemical conversion of poultry litter can offer better solutions where this waste can be used as a low-cost carbon source for the synthesis of Multiwalled Carbon Nanotubes (MWCNTs). In this study, efforts were made to utilize this cheap and plentiful carbon source for the synthesis of CNTs in the presence of Ni/Mo/MgO as a catalyst, through pyrolysis. For a better yield of carbon product, the optimum ratio for the catalysts (Ni/Mo/MgO) was found to be 4:0.2:1. Furthermore, the process parameters were also optimized for better carbon yield. A good yield of CNTs resulted from a pyrolysis time of 12 min, a temperature of 825 °C, and a catalyst weight of 100 mg. The structure and morphology of the produced nanotubes were confirmed through X-ray Diffractometer (X-RD) and Scanning Electron Microscopy (SEM). The environmental application of the nanotubes was tested in a synthetic chromium solution in the lab using a batch experiment. Different experimental conditions (pH, adsorbent dosage, and contact time) were optimized to improve the adsorption of Cr (VI) by carbon nanotubes and a UV-Visible spectrophotometer was used at 540 nm to measure the absorbance of Cr (VI). The results showed that up to 81.83% of Cr (VI) removal was achieved by using 8 mg of CNTs at pH 3 with 400 rpm at 180 min of contact time. Thus, it was concluded that poultry litter can be a useful source for the synthesis of MWCNTs and thereby removal of Cr (VI) from industrial tanneries’ wastewater.

The intensive search of new and cleaner energy catches interest in recent years due to huge consumption of fossil fuels coupled with the challenge of energy and environmental sustainability. Production of renewable and environmentally benign energy from locally available raw materials is coming in the frontline. In this work, conversion of the combined biomass (cotton gin trash, cow manure, and Microalgae [Nannochloropsis oculata]) through batch pyrolysis has been investigated. The effect of temperature to the production of energy fuels such as bio-oil, char, and biogas have been simulated considering the yield and energy content as responses. Result of the investigation generally revealed that the proportions of the different biomass did not significantly affect the product yield and energy recovery. Significant effect of temperature is evident in the simulation result of energy recovery whereby maximum conversion was achieved at 400°C for char (91 wt%), 600°C for syngas (22 wt%), and 551°C for bio-oil (48 wt%). Overall energy conversion efficiency of 75.5% was obtained at 589°C in which 15.6 MJ/kg of mixed biomass will be elevated to pyrolysis products.

PurposeUsing conservation of resources theory (COR), the authors test the combined effects of cynicism and psychological capital on counterproductive work behaviors (CWBs) mediated through emotional exhaustion.Design/methodology/approachThe authors use a time-lagged independent source sample (N = 181) consisting of employee–peer dyads from service industry in Pakistan.FindingsModerated mediated regression analyses indicated that emotional exhaustion mediates the relationship between organizational cynicism and counterproductive work behaviors. Psychological capital moderates the relationship between organizational cynicism and emotional exhaustion such that organizational cynicism is positively related to exhaustion when psychological capital is low. Furthermore, conditional indirect effects show that emotional exhaustion mediates the relationship between organizational cynicism and counterproductive work behaviors only when employees' psychological capital is low.Originality/valueThe study suggests new mechanisms and boundary conditions through which cynicism triggers CWBs. The authors discuss the implications of the study’s findings and suggest possible directions for future research.

[This corrects the article DOI: 10.1371/journal.pone.0152230.].

Purpose It is commonly observed in trainings that all trainees do not get satisfied with the performance of the trainer. The usual way to increase the satisfaction of trainees is a stress on improving task communication of the trainer. It is based on the assumption that effective task communication essentially fosters training effectiveness. This study aims to provide preliminary evidence that effective task communication can also obstruct training effectiveness besides promoting it. To achieve this objective, the authors hypothesized a dual-process model of training effectiveness based on uncertainty reduction theory. Design/methodology/approach This was a field study in which the authors collected time-lagged data from seven trainings. The trainings were designed to impart technical knowledge of multilevel analyses to professional social science researchers. Confirmatory factor analysis for ordinal indicators was used to test the measurement properties of the model and scales. Structural equation modeling for ordinal indicators was used to test hypotheses. Findings This study provided evidence of an overall positive effect of the trainer’s task communication on the trainee’s communication satisfaction. A complex mediation analysis also revealed the existence of two opposite psychological processes. While the first process transmitted the positive effect of task communication to communication satisfaction, the other process diminished this positive effect. Implications for the theory and practice of training are discussed. Originality/value Training scholars and practitioners universally believe that an effective task communication of trainers essentially promotes training effectiveness. This study has provided empirical evidence that this assumption is an incomplete picture of a complex reality that requires further investigation.

Grasses have been used widely to remediate contaminants present in domestic wastewater, but leachate generated from municipal solid waste that usually contain some concentrations of heavy metals has never been reported to be treated with grasses, especially Rhodes grass. A series of experiments was performed to investigate the contaminant uptake from municipal solid waste leachate by Chloris gayana (Rhodes grass) grown in combination with two commonly available grass varieties namely Vetiveria zizanioides (Vetiver grass) and Pennisetum purpureum (Elephant grass). Leachate used for the experiments had high values for chemical oxygen demand (5 g/L), pH (8.5), electrical conductivity (9.0 mS/cm), nitrates (182.1 mg/L), phosphates 6.4 mg/L along with heavy metals i.e. copper, zinc and manganese. Different dilutions of leachate ranging from 0 to 100% were applied in batches and their result showed that collectively all the grasses reduced overall contaminant concentrations. These were reported for chemical oxygen demand, electrical conductivity, nitrates, and phosphates reduced up to 67, 94, 94, and 73%, respectively. Metals uptake by grasses also showed a significant decrease in applied dose i.e. zinc (97%), copper (89%), and manganese (89%). Plant analysis showed that all grasses showed preference to heavy metals uptake e.g. Rhodes grass favoured up taking zinc, Elephant grass for copper and Vetiver grass preferred manganese. Overall growth performance of Rhodes grass was better in dilute leachate, whereas in more concentrated leachate, Rhodes grass did not perform better and production of biomass decreased. In Vetiver grass, root and shoot lengths decreased with increasing leachate strength, but the biomass did not change significantly.

Sustainable management of leachate produced from the dumpsite is one of the major concerns in developing countries Aquatic plants such as duckweed have the potential to remove pollutants from wastewater which can also be cost-effective and feasible options for leachate treatment. Therefore, the objective of our present study was to examine the growth and nutrient removal efficiency of duckweed (Lemna minor) on leachate. Three tests were performed each by growing lemna minor on synthetic leachate under controlled conditions and on dumpsite leachate under natural conditions. During each test, duckweed was grown in 300 ml plastic containers with a surface area of 25.8 cm.sup.2 . About 60 mg of fresh mass of duckweed was grown on 250 ml leachate at an internal depth of 9.5 cm. Results revealed that, in comparison to synthetic leachate, duckweed removed Chemical Oxygen Demand (COD), nitrogen (N), and phosphorous (P) more efficiently from dumpsite leachate under natural climatic conditions. However, the amounts of N and P absorbed into duckweed body mass were about 16% and 35% respectively more at synthetic leachate under controlled conditions. Maximum growth rate of duckweed (7.03 g m.sup.-2 day.sup.-1) was also observed for synthetic leachate in comparison to the growth rate of 4.87 g m.sup.-2 day.sup.-1 at dumpsite leachate. Results of this study provide a useful interpretation of duckweed growth and nutrient removal dynamics from leachate under natural and laboratory conditions.

In Pakistan, awareness regarding harmful effects of air pollution is minimal. There is absolutely no control on air emissions by industrialists and factory owners. Industrial activity is one of the major causes of the ambient air quality’s deterioration in the country. It has not been possible to assess the magnitude of industrial air pollution, as there is limited data available. Pakistan has responded to its environmental problems by passing laws and establishing environmental protection institutions. But in spite of all these measures, many aspects of environmental degradation have remained uncontrolled and under regulated. In addition to NOx and SOx, which are the major air pollutants, H₂S Gas, with a characteristic rotten egg smell and having an extremely low odour threshold (0.0004 ppm) and high toxicity, is also of a great environmental concern. 300 pm concentrations of H₂S in the air can result in death after long term exposures, while concentrations up to 2000 ppm for only a few minutes may be fatal for humans. Out of the 10,652 producible oil wells in Michigan, USA, 1,360 wells had H₂S levels exceeding 300 ppm. Keeping in view the poor response of the industrialists in Pakistan towards environmental laws and regulations, this study focuses on developing a technique for in-situ treatment of H₂S Gas at high temperatures by using TiO₂ nanoparticles, so that simultaneous destruction of this gas could be investigated for brick kilns, power generation and gasification processes which are carried out at high temperatures. Initial experimental results in the lab have shown a decrease of 99% in the gas concentrations. This technique is likely to help in the in-situ treatment of H₂S gas, resulting in considerable abatement of air pollution in Pakistan without installing any new device or changing the existing practices of exhaust gases by the industrialists.