468 research outputs found

    Next generation bioreactor models for wastewater treatment systems by means of detailed combined modelling of mixing and biokinetics

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    Wastewater treatment plants (WWTP) are needed to treat municipal wastewater to reduce the impact of pollutants on the environment and the ambient nature. The discharge of treated wastewater and the disposal of sludge from treatment plants treating domestic or industrial wastewater are subject to regulations imposed by the authorities. Moreover, during the wastewater treatment process greenhouse gas emissions are produced. These emissions from WWTPs are a matter of growing concern. The increased importance of wastewater treatment has led to development of mathematical models for optimization and design of wastewater treatment plants. WWTP modelling entails the modelling of the biological reactions (biokinetics) and underlying flow physics of the bioreactors (hydrodynamics). Currently, to model the hydrodynamics of a bioreactor, the tanks-in-series (TIS) modelling approach, which at best can model the flow variations in one direction, is widely used. These models assume a bioreactor as a series of completely mixed tanks and, hence, ignore any variation in the concentrations stemming from the design of a bioreactor or operational conditions. Therefore, these models eventually need rigorous calibration efforts to match measurements. This calibration is generally performed by manipulating kinetic parameters such as half saturation indices (K-values). The calibrated models are then used to assess or formulate different control strategies which includes the determination of an appropriate sensor location and a well-chosen setpoint for the controllers. In addition, the calibrated models are then extrapolated to predict the WWTP performance under different dynamic conditions (diurnal and dry/wet weather conditions) assuming that the flow patterns remain unchanged. In this thesis, it is hypothesised and confirmed that the bioreactors are not at all completely mixed and, hence, current models wrongfully calibrate the kinetic parameters by correcting for the errors induced by the over-simplified modelling of mixing. Consequently, the need for re-calibration arises at different operational conditions due to the limitation of the current models to incorporate changes in operational conditions. The thesis comprises of four parts. The first part provides the detailed account of CFD (computational fluid dynamics) modelling of WWTPs. Second part is about integration of CFD hydrodynamic models with the biokinetic models to evaluate the impact of mixing on the process performance. Third part is about model reduction, where detailed knowledge gained from the CFD-biokinetic modelling is used to develop simple but spatially localized compartmental model. The fourth part provides the insight about impact of mixing on the TIS model calibrations. In the first part, detailed CFD hydrodynamic modelling of a bioreactor of Eindhoven WWTP is performed. The impact of reactor configuration and process conditions on gas dispersion is observed. Potential regions of poor mixing are identified. The different flow patterns are discussed in detail. Similarly, hydrodynamic modelling of an oxidation ditch (OD) of La Bisbal d’Empordà WWTP is performed. The OD is equipped with four surface aerators (rotors). The impact of 2-rotor and 4-rotor strategy on the flow patterns is observed and discussed in detail. In the second part, the CFD hydrodynamic model of Eindhoven WWTP is extended by integrating it with bio-kinetic models, firstly with ASM1 and secondly with ASMG1. The impact of local mixing conditions on the dissolved oxygen (DO) and ammonium concentrations is observed and described. Regions of poor mixing are observed and hence their impact on overall process heterogeneity is discussed. The impact of DO variations on the nitrous oxide concentrations is also observed and it is shown that low DO concentrations tend to increase the nitrous oxide production. Similarly, the OD is also extended with a bio-kinetic model i.e. the ASM1 model. It is observed that the surface aerators have an inherent operational limitation and the DO concentrations at the bottom are very low (nearly anoxic). In the third part, the compartmental modelling (CM) was setup based on the DO concentrations using CFD-biokinetic model. A novel idea of cumulative species distribution (CSDs) to quantify the variations is introduced here as well. The CSDs serve as a decision support tool for the CM. A detailed stepwise procedure for the compartmentalisation is provided. Based on the procedure, the CMs are developed for both case studies. The CMs are also developed for different conditions and it is found that the CM network is different under varying conditions. Therefore, an idea of dynamic compartmental model is suggested at the end. Furthermore, this part also illustrates the impact of sensor location on the controller performance using a compartmental model. It is found that the controller’s performance highly depends on the sensor location and setpoint. An optimal sensor location can improve the effluent quality at reduced cost. In the last part, the impact of mixing on a CSTR based model calibration is shown. It is shown that the TIS models predict different estimated values under different mixing conditions. Therefore, it is important to take into account the mixing conditions before performing calibrations. The impact of sensor locations on the TIS model calibrations is also shown. The TIS model calibrations vary significantly if the sensor location for data collection are changed. It is concluded that this thesis has demonstrated the ability of CFD-biokinetic modelling to evaluate the process more accurately. Tthe derivation of a compartmental model has also provided the solution of high computational demands, commonly attributed to CFD modelling

    Impact of Exposure to Political Campaigns of Major Political Parties (PML-N, PTI & PPP) on Viewers’ Participation in Electoral Process

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    The General Elections 2013 in Pakistan under much tensed circumstance have utmost importance not only for Pakistan but also have vital significance for the major active players of the world. This study was designed to explore and document the exposure to political campaigns launched through television during general elections 2013 and its impact on viewers’ political participation. Survey research design was adopted to find out the viewers’ use of mass media and explore the factors behind a specific voting decision on them. The population-the whole university students-- was divided into two strata: natural sciences vs social sciences. From each strata 160 students, male and female students from BS and MA programs were taken as the unit of analysis. Stratified method for the specification of the demographic characteristics was adopted. 320 viewers were interviewed by using purposive sampling method through the questionnaire. The results figured out that most respondents (50.5%) used to watch television very frequently. Findings reveal that 54.5% viewers usually preferred to watch GEO TV. Results demonstrate that a significant number of viewers (60.5%) prefer to watch Discussions programs on TV during political campaigns. Viewers point of view reveal that 41% viewers think PML(N) launched most effective political campaign on television. Findings show that 45% respondents casted vote in favor of PML (N) and followed by PTI (32%), PPP (17%) and others (6%). Keywords: Politics, Election Campaigns, Television, Electoral Proces

    ORGANIZATIONAL JUSTICE AND EMPLOYEE’S JOB DISSATISFACTION: A MODERATING ROLE OF PSYCHOLOGICAL EMPOWERMENT

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    This investigation focuses on measuring the perception ofemployees regarding organizational justice (OJ) and jobdissatisfaction in the presence of interactive effect of psychological empowerment. The data have been collected from the employees of private universities in Lahore division using cluster sampling through random approach. The results of this investigation reveal that OJ has a negative association with the level of job dissatisfaction in the workplace. Moreover, the moderating role of psychological empowerment has weakened the negative relationship between OJ and the level of job dissatisfaction. There is scant literature found on the relationship between OJ and job dissatisfaction especially in the presence of interactive effect of psychological empowerment in the developed and the developing countries

    Determinant’s of Job Satisfaction & Employee Turnover in Pakistan Paint Industry

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    Purpose The aim of this research is to identify the factors that affect job satisfaction and turnover in the “Paint Industry” of Pakistan. Specifically, the study seeks to examine the relative effects of demographic and environmental factors on job satisfaction and turnover among the employees of such industries. Design/methodology/approach A scale development process was used. The first stage was a review of the literature on the determinants of job satisfaction in order to generate a pool of items that reflect job satisfaction along with turnover construct. A list of items was then gathered to cover all facets of job satisfaction and turnover. In?depth interviews and thorough questionnaires were employed to generate additional items. Findings Overall, the findings show that in an Eastern culture such as the Pakistan, especially in the Paint Industry, internal factors play a more important role as the determinant’s of job satisfaction or dissatisfaction that can lead to high or conversely, low turnover. Originality/value Given the importance of understanding the determinants of job satisfaction and turnover coupled with the dire need to fill the niche of research on the topic in our country; this study is of great importance to both academia and practitioners in the Paint Industry of Pakistan

    Interprofessional Education: A Basic Need of Healthcare Department in Pakistan

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    Inter professional education (IPE) is the core concept of healthcare department in most of the developed countries on both student and professional level. There is no objection on its necessity. Top ranking universities of the world, especially of developed countries are working on IPE. But some of developing countries like Pakistan are almost unaware of this concept. No one is having the basic concept of IPE, except few, and they are not practicing in IPE so far. Talking about Punjab, there is no awareness for the concept of IPE. It is the need of our healthcare department that we must introduce IPE to improve healthcare quality. This survey was conducted to check the readiness for IPE among pharm D and MBBS students in different institutes of medicine and pharmacy of Lahore. Team went to different pharmacy and medical colleges and asked the students to fill in a questionnaire having 19 items, which was rated by the students on Likert scale. The result shows a conflict in the opinion of pharmacy and medical students. Team also interviewed the respondents shortly. This interview showed many reasons explained by medical students for their response but the most prominent one was the superiority complex. The need of the hour is to introduce IPE in universities for changing the attitude of medical students towards IPE

    Biomarkers for impending risk of osteoporosis in premenopausal women

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    Objective: To compare \u27cytokines\u27 and \u27bone turnover markers\u27 in pre- and post-menopausal women and identify their relationship with bone mineral density (BMD) in both groups. Study Design: A cross-sectional study.Place and duration of study: Department of Biological & Biomedical Sciences, The Aga Khan University, Karachi, Pakistan, from June 2017 to August 2019.Methodology: Groups comprised of healthy premenopausal and postmenopausal women from the general population belonging to different ethnic groups and socio-economic status. Serum cytokines and bone turnover markers were assessed by solid-phase immunoassays, BMD (gm /cm2)] measurement was performed by dual-energy X-ray absorptiometry at the hip, lumbar spine, and proximal femur. Results were interpreted as a sum of T scores calculated by BMD of the above-mentioned sites.Results: Cytokines and bone turnover markers were significantly high in post-menopausal women (p\u3c0.001). A negative correlation (r = 0.32) of TNF α with BMD (total T scores) observed in premenopausal women was found to be significant, however, no significant association of BMD was detected in post-menopausal women.Conclusion: There is an increase in the production of cytokines and bone turnover markers after menopause. TNF-α follows this usual pattern of increase in post-menopausal women and can predict impending bone loss and osteopenia in premenopausal females. Therefore, estimation of this cytokine in pre-menopausal women can give a fair indication of a decline in BMD, bone health, and risk of future osteoporosis. Key Words: Bone mineral density, Cytokines, Bone turnover markers, Osteoporosis
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