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CFD applications to water and wastewater treatment

  • 1.  CFD applications to water and wastewater treatment

    Posted 06-11-2014 05:22 PM
    Hello EWRI Colleagues, 

    I just graduated from a PhD program in Civil and Environmental Engineering at University of South Florida. In my PhD study, I studied disinfection process for water treatment and stabilized pond for wastewater treatment using computational fluid dynamics (CFD). CFD technology has been prevalent in aerospace engineering and mechanical engineering for many decades. But it was not popular in environmental engineering until recently. During a literature review, I noticed that there are more researchers outside the United States (e.g., Canada, UK, Germany, and France etc.) concerning improving the performance of disinfection tank and willing to explore the disinfection process using modeling tools (mostly CFD). I think it is an interesting phenomenon. But it may not be true. Please correct me if you happen to have a better knowledge in this field. Any other comments are also welcome.

    Thanks,

    Jie

    -------------------------------------------
    Jie (Jay) Zhang, Ph.D.
    Department of Civil and Environmental Engineering
    University of South Florida
    Tampa FL
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  • 2.  RE: CFD applications to water and wastewater treatment

    Posted 07-30-2014 08:48 AM
    Jay, congratulations on completing your PhD degree and welcome to the practice and teaching of civil and environmental engineering. As your District 5 Director I visited your outstanding program and faculty a few years ago. Your graduation indicates all is well with your program.

    I recall computational fluid dynamics models being used to design and analyze unit wastewater and drinking water treatment processes at least back to the 1990s, in Australia at Cook University in Townsend, then for a sedimentation basin as I recall. The faculty were protegees of Jorg Imberger from the University of Western AU research program on stratified reservoirs.

    The key to use has always been a well defined purpose and a means by which a PE can establish the calculations are necessary, useful and accurate. You have completed your terminal degree so perhaps your practice and teaching will help provide the guidance on when and how to use computational fluid mechanics. You and like-minded environmental engineers could propose an EWRI task committee to define the need and then write the Manual of Practice to support the use of these very flexible models in practice where needed.

    Looking forward to your contributions to the profession.

    -------------------------------------------
    Steven McCutcheon Ph.D., P.E., D.WRE, F.EWRI, M.ASCE
    Nat Expert, Sr Envir Engr
    Athens GA
    (706) 543-6972(706) 543-6972
    -------------------------------------------




  • 3.  RE: CFD applications to water and wastewater treatment

    Posted 07-31-2014 09:26 AM
    Jay, Congratulations as well, I have never heard of CFD using in analyzing drinking water and wastewater...do happen have any articles or journals about this modeling? I would love to read up....


    Thanks,
    Rishabh

    -------------------------------------------
    Rishabh Iyer Aff.M.ASCE
    Engineer
    TRC Environmental
    Lowell MA
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  • 4.  RE: CFD applications to water and wastewater treatment

    Posted 08-01-2014 11:38 AM
    Hi Rishabh, thanks! There are a lot of papers on CFD applications to water and wastewater treatment. But since you haven't read one, I'd suggest you read some review paper first. The links below are some recent literature reviews of CFD applications to disinfection and membrane for water treatment. I think you may have an interest in reading them. 
    Rauen, W. B., Angeloudis, A., & Falconer, R. A. (2012). Appraisal of chlorine contact tank modelling practices. Water research46(18), 5834-5847.
    http://www.sciencedirect.com/science/article/pii/S0043135412006008

    Zhang, J., Tejada-Martínez, A. E., & Zhang, Q. (2014). Developments in computational fluid dynamics-based modeling for disinfection technologies over the last two decades: A review. Environmental Modelling & Software58, 71-85.
    Ghidossi, R., Veyret, D., & Moulin, P. (2006). Computational fluid dynamics applied to membranes: State of the art and opportunities. Chemical Engineering and Processing: Process Intensification45(6), 437-454.

    Jay

    -------------------------------------------
    Jie (Jay) Zhang A.M.ASCE
    University of South Florida
    Tampa FL
    http://jiez.weebly.com/
    -------------------------------------------




  • 5.  RE: CFD applications to water and wastewater treatment

    Posted 08-01-2014 11:38 AM
    Thank you Dr McCutcheon, your advice of writing a manual of practice is exactly my future plan. And currently I am searching for the best group and the best place where I can carry out this plan. 

    I have seen that CFD has been included in some guidelines such as 
    Shilton, A. & Harrison, J. 2003 Guidelines for the Hydraulic Design of Waste Stabilisation Ponds. Massey University, New Zealand. http://www.bvsde.paho.org/bvsacd/agua2003/hidra.pdf 

    And Tsungchu (George) Chien from California Department of Public Health also provided me some useful information:
    U.S. EPA mentioned CFD briefly as one of the possible solutions of improving mixing in the Stage 2 DBPR OEL , p.6-5 (http://www.epa.gov/ogwdw/disinfection/stage2/pdfs/draft_guide_stage2_operationalevaluation.pdf)
    Water Research Foundation did a research of CFD of UV reactor several years ago (http://www.waterrf.org/PublicReportLibrary/4107.pdf)

    I love exploring in this area and will continue promoting CFD applications to environmental engineering.

    Thank you again for your concerns.

    Jay

    -------------------------------------------
    Jie (Jay) Zhang A.M.ASCE
    University of South Florida
    Tampa FL
    http://jiez.weebly.com/
    -------------------------------------------




  • 6.  RE: CFD applications to water and wastewater treatment

    Posted 08-05-2014 09:46 AM

    My hearty congratulations for getting Ph.D
    -------------------------------------------
    D. Thangaraj M.ASCE
    Executive Engineer
    Subramaniapuram TN
    914371 235488
    -------------------------------------------




  • 7.  RE: CFD applications to water and wastewater treatment

    Posted 08-05-2014 09:47 AM
    Hi Jay
    I tried to post something similar the other day but just couldn't find it posted, so I am doing this again. In a nutshell, the attached paper illustrated a case of applying CFD to an aeration tank and comparing the results to experimental data.

    The only problem is the inherent assumption of constant bubble size, and the requirement to measure bubble sizes in experiment before any comparison of simulated and observed data can be made.

    Although it is not currently possible to estimate bubble size as it is dependent on the orifice of discharge and other things, it is possible to develop a relationship of bubble size with depth for a stream of rising bubbles. The phenomenon of bubble size variation with depth in a column of liquid (water) obeys the universal gas law, as well as Dalton's Law and Henry's Law; and, although the position of bubbles depends upon the hydrodynamics of the liquid and gas flows, the size of bubbles is always under good regulations by those physical laws.

    The ASCE is currently updating the Standard Guidelines for In-Process Oxygen Transfer Testing (ASCE/EWRI-18-96) which sets standards for measuring oxygen transfer efficiency (OTE) of aeration equipment. If CFD is a valid method, it can be incorporated into this Standard.

    Would you be interested in assisting developing a mechanistic model and then incorporating such model into CFD simulation? If it works, it will be a revolutionary breakthrough and would translate into huge economic savings in the operation of a WWTP.
    Regards,
    JL

    -------------------------------------------
    Johnny Lee P.Eng, CP, M.ASCE
    Kitchener ON
    1519 8948591
    -------------------------------------------




  • 8.  RE: CFD applications to water and wastewater treatment

    Posted 10-27-2014 07:32 PM
    Hi Johnny, 

    Thanks for responding to this post. 

    I also encountered such a bubble problem in modeling disinfection since gas bubbles exist in ozone disinfection as well. But I neglected the effect of gas phase as the majority of previous studies did for two reasons: 1) to reduce the complexity and computational cost; 2) the impact of gas flow on water flow in full-scale disinfection tanks is negligible since the ratio of gas flow rate to water flow rate is small (1%~3%).

    Actually predicting bubble size and growth has been studied in multi-phase flow modeling for a while. Note that multi-phase flow modeling is an important branch of computational fluid dynamics (CFD). Attached is an examples of the papers on modeling bubble growth using CFD. The Darton model mentioned in this paper is a semi-empirical model for bubble growth in fluidized beds proposed by Darton et al. (1977). However I haven't seen a study on modeling bubble growth in aeration using CFD. So I think It is definitely an interesting topic to develop a mechanistic model for bubble growth in aeration and then incorporate it into CFD simulation. Although I may not have time to do it by myself now, I would like to provide some help in terms of suggestions and comments if you happen to have someone working on it. I believe it could be a good topic for a thesis or dissertation. 

    Thanks,

    Jay

    -------------------------------------------
    Jie Zhang A.M.ASCE
    University of South Florida
    Tampa FL
    http://jiez.weebly.com/
    -------------------------------------------




  • 9.  RE: CFD applications to water and wastewater treatment

    Posted 10-28-2014 12:25 PM

    Hi Jay
    Thanks for your continuing interest in this pursuit. Right now I am aiming to publish my findings in the Journal of Environmental Engineering and my deadline is Nov 6th (See following email from the Editor copied over). I am hoping it will be published shortly after the peers' review.

    Unlike ozone disinfection, bubble growth is critical for effective oxygen transfer. As Bewtra et al. long ago determined:"The amount of oxygen transfer depends upon the size of the air bubble, the number of air bubbles present in the liquid, the concentration gradient, and the overall diffusion coefficient during the ascent of the bubble." Boyle's Law states that for a fixed mass of gas, the gas volume is inversely proportional to the pressure at a constant temperature. Hence, in a 17 foot tank, a conserved bubble would experience a 50% increase in volume while rising. This increase in interfacial area tremendously affect the transfer rate and must be modeled correctly. Once this thesis paper is published you should be able to see if my derivation is valid, and decide whether such model can be incorporated into CFD.

    I will keep you posted.

    Thanks
    JL
    Ref.:  Ms. No. EEENG-2080
    Mathematical Formula for Oxygen Transfer Scale-up in Subsurface Aeration
    Johnny Lee, M.Sc.

    Dear Mr. Lee,

    Your Technical Paper, listed above, has completed a review for publication in ASCE's Journal of Environmental Engineering. The editor has requested that a revised manuscript be prepared based on the reviewers' evaluations (shown at the end of this email) and submitted for re-review by 11/06/2014.


    Please submit the revised manuscript and a detailed response to the reviewers' criticisms by logging onto the Editorial Management system at http://jrneeeng.edmgr.com/ and clicking on the "Submissions Needing Revision" link.

    Be advised that the editor may request further revision or decline your revised version if all of the reviewers' comments have not been adequately addressed.


    Comments from the Editor and Reviewers can be found below.

    We look forward to receiving your revised manuscript.

    Sincerely,

    Jennifer Chapman
    Editorial Coordinator

    Reviewers' comments:

    Editor: Based on our recent email correspondence with the author, we are returning this manuscript to the author for revision prior to conducting any further review.  We are also forwarding comments from one reviewer noted below for consideration by the author. If the authors wish to revise and resubmit a manuscript, then please prepare a completely new submission.  Thank you.


    Reviewer #2: This paper presents original work that is interesting.
    However, it is not written in a format consistent with the journal and this makes it difficult to follow.  All of the equations need to be re-formatted to a style consistent with journal conventions and all variables clearly defined.  The text also must be revised as it is too informal (e.g. use of personal pronouns).
    -------------------------------------------
    Johnny Lee P.Eng, CP, M.ASCE
    Kitchener ON
    1519 8948591
    -------------------------------------------




  • 10.  RE: CFD applications to water and wastewater treatment