Dear Hopewelll

I have requested Prof Geoffrey Simate at Wits to give you his comments to your question.

John

I would start learning the R language.  This will provide you with a free software with dramatically more utility and ease of use than working with VB. 

Why use visual basic for simulating a waste water treatment plant?

You need to use a format process simulation package like HYSYS from AspenTech Corporation. This software can model all the equipment used in the plant and has complete thermodynamics models that will help you perform your mass and energy balances in this system.

You can download a trial copy of HYSYS from:

aspentech.com

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

Try to program in MatLab - simulink instead to program in VB or use hydromantis gps-x, a specific  package to simulate wastewater treatment plant. 

Leonardo

Hopewell,

You should be able to call a excel spreadsheet/Visual basic  program from all three versions of Hysys  (KBC, Honeywell and Aspen).  That will probably make it more acceptable for others to use but probably won't make it any more accurate. What functionality are you trying to get from the simulator that you can't do in excel?  Hysys based simulators are very good for sizing pumps , compressors etc. and they can also do the reactor modelling in an environment that is easier for others to use and the thermodynamic calcs are much easier to do in the Hysys environment. 

Simpler and easier to do an Excel spreadsheet.  You also have tools at your fingertips for analysis of the data you are using, and it is transportable.

I love spreadsheets and that's what I've been using throughout my masters. However I wanted to put this on a simulation software. Thank you for all your inputs.

Buy a verified simulation software package, but I recommend using an Excel spreadsheet to confirm specific conditions for steady state conditions of importance, since it will be an important check on the suitability of your simulation results. Remember "all models are wrong; they are just interesting". 

Harlan,

Please explain what you mean by all models are wrong. The models I'm using have been validated and well researched.

Hopewell,    

All models are wrong but most models are useful is a very useful phrase to remember.  There may indeed be a few models that are always right but that just proves that the statement itself is only a model like most other models that is useful but not always right.  

Good models usually are a good depiction of what they are modeling but in my experience they are never perfect.  Even models that have serious flaws can be very useful over the range of data where they were developed.  But be cautious when you try to make prediction outside of the range a model has been developed over because most "Models" in reality are just glorified curve fits,  the best you could do with the information available. Very useful but not perfect

I should know I've developed thousands of models during my career - most of them are quite useful but I'm pretty sure I have never developed one that is perfect.

Thank you Rick.  

If I may, the one "simulation" model that is correct is "reality" in real time.  Reality never repeats itself; although, some repetitions seem close.  "Reality" is tough to emulate, especially the non linear kind, and all simulation models use approximations with explicit and implicit devices for convergence when non linearity is involved. As Rick has pointed out, these devices are often simply data expressed in curves or algorithms developed from past predictions.  By virtue of the first premise concerning the non repeat-ability of reality, this in itself makes the results wrong.  As another factor, even the tools for monitoring for the inputs to the models are often +/-25% error.

Simulation models are in my view useful to evaluate "what if scenarios", to give predictions in process decisions for systems, or even simple life choices. These models, however may also cause large errors, which in turn can cause wrongful thinking and disasters.  Verify and check your simulation model with a steady state mass balance model calibrated using known conditions and results. This is the same as saying, know how to calculate the solutions by hand in standard engineering practice.before you use a model.

Thank you,

I fully understand what you mean now. Any way we'll never fully understand what these bacteria are doing in these bio-processes. I agree the models are not perfect, they just help us understand the system, and design  and also to operate the system. To that degree they are important to us as bio-process engineers. Our aim is to understand the system, to design it and operate it and these steady state and dynamic models are just as sufficient to meeting our objectives. But I'd be careful to say they are wrong when I do not know the real answer :) :) very thoughtful and useful information there, thank you very much. 

i agree with Kelly answer

You may enhance substantially the Excel spreadsheet capability to perform simulations with macros written in VBA (Visual Basic for Applications). Years ago, I used that strategy for a study on the energetic optimization and adaptive control of aerobic fermenters:

Thesis Controlo do Oxigénio Dissolvido em Fermentadores para Minimi...

Carlos,

I believe your resource could be very useful to me if it was in English. thanks 

Old-style BASIC code is available, but written so that it may be simplest to start from scratch!

Pascal code is also available for ASM1 and may be a better starting point. There is some Fortran code in the COST 682 report comparing different wastewater process simulators for use with the IWA Benchmark model #1.

I agree with comment of Dudley above

Go to Sourceforge.

Search for Killarney.

This is an unfinished wastewater flowsheet package, with code for ASM1, ASM2 and ASM3.

Thank you everyone,

I have got a hold of WEST and it provides a very good modelling environment and that's what I'm using to do my research. thank you 

If you wanted a packaged system you could have looked at STOAT, which I help develop :-) It is has the advantage of being free. However, WEST in principle is easier to customise if you need to include the behaviour of specific chemicals.

Jeremy,

Thank you :) thank you for the valuable contribution you've made in the water research community. I will have a look at it. 

I will go through your publications, you've written on very interesting and hot topics.