278 research outputs found
Optimization of Wastewater Treatment Process in a Bioreactor Through Hydrodynamic-biokinetic Modeling and Experimental Studies
No full textMembrane bioreactor has emerged as one of the leading technologies for treating municipal and industrial wastewater due to its efficiency in producing high-quality effluents. One of the significant challenges in bioreactors is the high energy and operating costs. The diffused aeration process of a bioreactor is the most energy-intensive operation amounting to 45-75% of the plant energy costs. This study attempts to optimize the wastewater treatment (WWT) process in a bioreactor through modeling and experimental studies. The overall aim is to develop efficient models which can be used to reduce the treatment costs of the WWT process while increasing the treatment efficiency.
As a first objective, a multiphase mixture computational fluid dynamics (CFD) model was developed using k- turbulence closure equations and a discrete population balance model (PBM) add-on with specific bubble classes to predict the oxygen mass transfer in synthetic water. The validated model was extended for sensitivity analysis for a diffused aeration system in a bench-scale aeration tank. Results show that the volumetric oxygen mass transfer coefficient increased by 15 %, with a decrease in air bubble size by 10 %. In a diffuse aeration system, the air bubbles had a wider distribution, with a larger diameter near the bottom of the bioreactor, and narrow distribution, with a smaller bubble size at the top of the bioreactor.
As a second objective, an integrated model was developed by combining the multiphase CFD model, the PBM sub-model, an activated sludge submodel, and a combined extracellular polymeric substance (EPS) – soluble microbial product (SMP) (CES) submodel to investigate the oxygen uptake rate, the aeration efficiency, and treatment efficiency in bioreactors. Three different scale bioreactors, namely, i) case 1- laboratory, ii) case 2 – pilot, and iii) case 3- full-scale system, were studied. The model predictions on water quality were validated well with the experimental results. The validated model was used for sensitivity analysis to identify optimum conditions. The maximum percentage reduction in chemical oxygen demand and total nitrogen were 17 % and 18 %, respectively, for case 3. Also, a reduction of 32 % in the cost of aeration was observed when the bubble size was reduced to 5 mm (from the current value of 7 mm).
The third objective focused on developing a multiphase CFD – porous- CES model to investigate the effect of hydrodynamics on biofouling and the effect of the EPS and SMP on the cake layer formation. The developed model was validated with experimental observations from the laboratory-scale ultrafiltration hollow fiber membrane setup. Observations showed that as the filtration time increased, the transmembrane pressure (TMP) increased, and the permeate flux decreased. Furthermore, in experimental set 2 (synthetic wastewater with sludge seeding), the effect of cake deposition on TMP and permeate flux was 17% and 1.5% higher, respectively, compared to experimental set 1 (synthetic wastewater with yeast sludge). The validated model was then used to investigate the sensitivity of the CES submodel by comparing it with the sectional resistance submodel. It was observed that the sectional resistance model underpredicted the mass of cake deposited by 13 % and overpredicted the limiting flux by 4 %. The results suggest the importance of accounting for the influence of EPS and SMP on the cake layer formation and biofouling.
The fourth objective of this thesis reports a BioWin©- ASM for optimizing the biological nutrient removal (BNR) in a 55 million liters per day sewage treatment plant (STP). The proposed modification was to incorporate an intermediate virtual anoxic zone to achieve simultaneous nitrification-denitrification and total dissolved phosphorus (TDP as PO4) removal. The hydraulic residence time (HRT), dissolved oxygen (DO), and mixed liquor suspended solids (MLSS) of the bioreactor were varied to identify the optimum operating conditions. The optimum DO and MLSS levels were identified as 4 mg/L and 4000 mg/L, respectively, and the optimum HRT was found to be 2 h. in the aeration zone, 1 h. in anoxic, and 3 h. in the reaeration zone. Implementing these modifications in the STP, with minimal operational interventions and no capital costs, improved its performance as predicted by the model. The total nitrogen and TDP (as PO4) reduced from 20 mg/L to 8 mg/L and 3.5 mg/L to 0.9 mg/L, respectively, and met the revised discharge standards. This intervention gave a cost saving of approximately 5.6 million USD.
This work has demonstrated that the numerical models can be successfully used to optimize the treatment efficiency while reducing the capital (membrane replacement) costs and operating (aeration) costs of a bioreactor. The time and efforts required for identifying the optimum conditions through numerical modeling are significantly less than physically characterizing the bioreactor (and varying the conditions to optimize them)
Bibliographics for the 983 eprints in the live archives of E-LIS : trends and status report up to 7th July 2004, based on author-self-archiving metadata
No full textThe priority for ideas and philosophy related to "Network Theory" have been traced back and documented by Braun(2004),and credit goes to Karinthy(1929).The IT has empowered to realise it, as the most practical phenomena and it is no more a humour. The OAI (Open Archives Initiatives)and ACIS (Academic Contributor Information System)are progressive in the direction ,which may lead to realise the "Collective Genius" at global level. Focus of present study is on Author-Self-Archiving (A-S-A)Metadata of the 983 Eprints in the Live Archives of the E-LIS (EPrints of Library and Information Science),which were approved till 7th July 2004.The A-S-A Metadata was used for librametric analysis. Self-explanatory bibliographics are illustrated.The highlights include: Conference papers (34%); highest approval, June 2004 (28%); published archives (76%);not refereed (52%); not in public domain (60%); highest self-archiving-author (De Robbio, Antonella).The Nos. of EPrints having single JITA domain specifications were: Theoretical and general aspects of libraries and information(27); Information use and sociology of information(80);Users,literacy and reading(13);Libraries as physical collections(30);Publishing and legal issues(57);Management(13);Industry, profession and education(36);Information sources, supports, channels(113) ; Information treatment for information services, Information functions and techniques (101); Technical services libraries, archives and museums(25); Housing technologies(1); Information technology and library technology(92); and Inter-domainery (395) i.e. having specifications of two or more than two JITA classes
Refinement of solutions to the linear complimentarity problem
No full textNash equilibrium;game theaory;matrices
Recent Trends in Value Addition in Coffee
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
In vitro bio-activity studies on Antioxidant Enriched Mixed fruit Jam
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Recent trends in soft beverages
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Numerical modelling of oxygen mass transfer in diffused aeration systems: A CFD-PBM approach
No full text•Multiphase CFD model coupled with discrete PBM equation.•Effective air bubble size reduces with height of water column.•Bubbles have a wide distribution, with larger diameter near bottom.•Bubbles have a narrow distribution with small bubble size at the top.•Higher H/B ratio result in increased rate of DO saturation at fixed airflow rate.
The diffused aeration process is the most energy-intensive operation of bioreactor treatment, amounting to 45–75 % of the plant energy costs. To improve its efficiency, it is essential to measure the oxygen transfer rate from the aerators to wastewater. In this study, a multiphase mixture computational fluid dynamics (CFD) model is developed using k-ε turbulence closure equations along with a discrete population balance model (PBM) add-on with specific bubble classes, to predict the oxygen mass transfer. The transfer of oxygen species from air to water is modeled using the species transport model. The PBM is used to analyze the formation, growth, breakage, and coalescence of air bubbles. The validated model is then extended for sensitivity analysis for a diffused aeration system in a bench-scale aeration tank. Results show that, the volumetric oxygen mass transfer coefficient increases by 15 %, with a decrease of air bubble size by 10 %. The air bubbles have a wider distribution, with a larger diameter near the bottom of the bioreactor and a narrow distribution with a smaller bubble size at the top. Results show that, in the bioreactor, the dissolved oxygen concentration reaches the equilibrium or saturation value when the height by breadth ratio is 2.5 and does not increase further with increase in height of the water column. Also, the air bubble size of 6 mm was the efficient bubble size for a fixed airflow rate of 1.45 m3 h−1
Scientometric portrait of Nobel laureate Leland H. Hartwell
No full textLeland H. Hartwell was honoured with the Nobel Prize in Physiology or Medicine (2001) at his 62 years age and at 41 years of research publishing career. The first contribution of the author was in 1961 at the age of 22. The number of his contributions in a year peaked in 1997 when it touched 8. He had 108 publications during 1961 – 2001 in domains: Molecular Biology of Cell Cycle Regulation (43), Genetics of Cell Division (48), Genomic Re-arrangement and DNA Repair (9), Molecular Genetics of Yeast Cell Fission (5), and Drug Target Interaction (3) which were analysed for authorship pattern with his 101 collaborators. Most active researchers having number of publications with Leland H. Hartwell were : Weinert, T. A. (10), Garvik, B. M. (8), McLaughlin, C. S. (8), Jenness, D. D. (5). His productivity coefficient was 0.76 which clearly indicates that his productivity increased after 50 percentile age. Highest collaboration coefficient (1) for Leland H. Hartwell was found during 1963-1965, 1968-1969, 1977, 1981-1983, 1985-1990, 1996 and 1998-2001. Journals have been the most preferred channel of communication where, as many as 96 papers out of 108 have been published. The core journals publishing his papers were: Cell (14), Genetics (12), Mol. Cell Biol. (8), J. Bactariol. (7), J. Cell Biol. ( 7), Science (7) J. Mol. Biol.(6), Exp. Cell Res. (5), and Proc. Nat. Acad. Sci.(5). Publication density is 2.63 and Publication concentration is 14.63. Most prolific keywords in titles of publications were: Saccharomyces cerevisiae , Yeast , Cell division cycle , RAD9, DNA Damage , Genes , Cell cycle, Genetic control , Check point (s) , Cell division , Mutant of Yeast
Preferential Regulatory T-Cell Generation from Memory CD4+ T-Cells Is Deficient During Acute Exacerbation of Multiple Sclerosis
No full textThe general metadata -- e.g., title, author, abstract, subject headings, etc. -- is publicly available, but access to the submitted files is restricted to UT Southwestern campus access and/or authorized UT Southwestern users.Multiple sclerosis (MS) is an immune-mediated disease with reported defects in thymic T-cell output. Thymically-derived natural regulatory T-cells (nTregs) play a vital role in suppressing autoimmune responses. We have previously shown that, in humans, all activated T-cells attain transient FOXP3 expression that correlates with suppressive ability. In fact, peripheral generation of induced Tregs (iTregs) is likely the dominant source of regulatory cells in healthy adults and even more so in MS patients. Through the use of a sensitive flow-based suppression assay, we observed that memory and naïve CD4+CD25-FOXP3- T-cells both developed regulatory ability subsequent to a variety of activating stimuli. This suppressive ability was greater than that observed in nTregs and not explained by exhaustion of nutrients or competition for APCs. While blockade of activation using anti-IL-2, CTLA-4 Ig, anti-TGF-β, indomethacin or cyclosporin A did not affect iTreg generation, methotrexate preempted the induction of regulatory ability. Moreover, irradiation of iTregs also abrogated regulatory function. Interestingly, memory-derived CD25+ iTregs displayed significantly greater activation-induced FOXP3 induction compared to naïve counterparts, and exhibited significantly enhanced suppressive function per cell. Furthermore, the CD25- fraction of activated memory-derived iTregs also demonstrated regulatory function not observed in naïve counterparts. In particular, this induced regulatory population was present in both healthy controls and quiescent MS patients, but deficient during MS acute exacerbation. These studies suggest that iTreg development and function may vary dependent on precursor origin, and that clinical recovery from exacerbation to ix quiescence in MS is associated with a restoration of function in memory-derived CD4+CD25-FOXP3- Tregs
Scientometric Dimensions of Innovation Communication Productivity of the Chemistry Division at Bhabha Atomic Research Centre
No full textScientrometric analysis of 1733 papers published by the teams comprising total of 926 participating scientists at Chemistry Division of Bhabha Atomic Research Centre (BARC) during 1970-1999 in the domains: Radiation & Photochemistry and Chemical Dynamics (649), Solid State Studies (558), Inorganic, Structural and Materials Chemistry (460) and Theoretical Chemistry (66) were analysed for yearwise productivity, authorship pattern and collaboration. The highest number of publicationsin a year were 98 and 104 produced in 1989 and 1996 respectively. Average number of publications per year were 57.76. Highest collaboration coefficient 1.0 was in 1977 and 1999.
The authors with most prolific publications were J. P. Mittal (204), R. M. Iyer (190), J. V. Yakhmi (156), V. K. Jain (106), Hari Mohan (96), K. N. Rao (92), I. K. Gopalakrishnan (80), P. N. Moorthy (78), T. Mukherjee (77), and S. K. Kulshreshtha (74).
The core journals preferred for publishing with high number of publications were: Indian Journal of chemistry - A (96), Radiation Physics and Chemistry (92), Chemical Physics Letters (67), Journal of Physical Chemistry (59) and Indian Journal of Chemistry (45). Publication concentration was (28.57%) and publication density was (5.48). Top ranking journals publishing chemistry division,BARC publications were from UK (471), India (326), The Netherlands (302), USA (277) and Switzerland (104)
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