WRc STOAT: Tutorials Guide

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A useful tutorials guide for the WRc STOAT wastewater modelling software. This contains several tutorials to help new users get accustomed to creating and running models of wastewater treatment plants. It is suitable for use with beginners and intermediate users of STOAT versions 4 and 5.


<p>Copyright WRc plc</p> <p>The contents of this manual and the accompanying software are the copyright of WRc plc and all rights are reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of WRc plc. The information contained in this manual is confidential and restricted to authorised users only. This manual and the accompanying software are supplied in good faith. While WRc plc have taken all reasonable care to ensure that the product is error-free, WRc plc accepts no liability for any damage, consequential or otherwise, that may be caused by the use of either this manual or the software.</p> <p>TABLE OF CONTENTS</p> <p>1 2. 2.1 2.2 2.3 2.4 2.5 3. 3.1 3.2 3.3 3.4 4. 4.1 4.2 4.3 4.4 5. 5.1 5.2 5.3 5.4 6. 6.1 6.2 6.3 6.4 7. 7.1 7.2 8. 8.1 8.2</p> <p>INTRODUCTION GETTING STARTED CREATING A NEW SEWAGE WORKS RE-USING AN EXISTING SEWAGE WORKS CREATING A NEW RUN SELECTING REPORTING OPTIONS COMPLETING A RUN TUTORIAL 1: A SIMPLE WORKS BUILDING A SIMPLE ACTIVATED SLUDGE WORKS RUNNING THE SIMULATION LOOKING AT YOUR RESULTS SUGGESTIONS FOR FURTHER SIMULATIONS TUTORIAL 2: NUTRIENT REMOVAL BUILDING THE WORKS ADDING MIXED LIQUOR RECYCLES RUNNING THE SIMULATION SUGGESTIONS FOR FURTHER SIMULATIONS TUTORIAL 3: STORM TANKS, PRIMARY TANKS, ACTIVATED SLUDGE AND TRICKLING FILTER BUILDING THE WORKS CONSTRUCTING A STORM RUNNING THE SIMULATION SUGGESTIONS FOR FURTHER WORK TUTORIAL 4: A MORE COMPLEX WORKS BUILDING THE WORKS PROGRAMMING A CHANGE RUNNING THE SIMULATION SUGGESTIONS FOR FURTHER SIMULATIONS TUTORIAL 5: USING THE PID CONTROLLER TO MAINTAIN A CONSTANT WETTING RATE ON A TRICKLING FILTER BUILDING THE WORKS RUNNING THE SIMULATION TUTORIAL 6: USING SENSITIVITY ANALYSIS FUNCTION WITHIN STOAT BUILDING THE WORKS AND RUNNING THE FIRST SIMULATION CARRYING OUT THE SENSITIVITY ANALYSIS</p> <p>1 2 2 4 4 6 7 8 8 10 19 20 22 22 23 26 31</p> <p>32 32 33 35 37 38 38 39 42 42</p> <p>43 43 44</p> <p>51 51 53</p> <p>9. 9.1 9.2 9.3 9.4 9.5 10. 10.1 10.2 10.3</p> <p>TUTORIAL 7 PRIMARY SEDIMENTATION AND NITRIFYING TRICKLING FILTER BUILDING TRICKLING FILTER WORKS GENERATING INFLUENT FILE TUTORIAL 7A: RUNNING SIMULATIONS/LOOKING AT RESULTS TUTORIAL 7B: RUNNING SIMULATIONS/LOOKING AT RESULTS SUGGESTIONS FOR FURTHER WORK TUTORIAL 8 - SEQUENCING BATCH REACTOR BUILDING SBR WORKS GENERATING THE INFLUENT FILE RUNNING SIMULATIONS AND LOOKING AT THE RESULTS</p> <p>57 57 58 60 63 67 68 68 69 70</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>STOAT TUTORIALS GUIDE</p> <p>1.</p> <p>INTRODUCTION</p> <p>This guide is intended to take you through using STOAT, by building and running a series of example sewage works. If you have a specific requirement for STOAT, and would like to see this covered by the tutorials for other users, please contact us and we will prepare one. The structure of this guide is: Section 2 covers common material on using STOAT. The subsequent sections present a range of worked examples: Section 3 covers the modelling of a simple activated sludge works. Section 4 extends this works to model nutrient removal. Section 5 removes the nutrient removal option and extends the works to use a tertiary biological filter for nitrification. Section 6 extends the simple sewage works of Section 4 to multiple parallel trains and describes the effect of losing 2 aeration lanes for maintenance purposes. Section 7 uses a PID controller to continuously adjust the flowrate to a filter to achieve a constant wetting rate on the filter. Section 8 describes the use of the Sensitivity Analysis algorithm within STOAT to assess the effect of varying the settling velocity in a primary tank. Section 9 covers the use of the Original BOD model for trickling filters and compares these results with the new biofilm growth model (COD) within STOAT. Section 10 gives a tutorial showing how to set up and run an SBR model.</p> <p>1</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>2.</p> <p>GETTING STARTED</p> <p>Start STOAT by double-clicking the STOAT icon from the Windows Program Manager. When STOAT has loaded you are presented with a blank screen with five menu options, 'File', Edit, Options, Tools and Help. Select 'File.' If you are starting a tutorial for the first time select 'New Works'; if you are continuing a tutorial from where you left, select 'Open Works.'</p> <p>The 'New Works' option asks you to give a name for the works. We suggest that you use the names 'Tutorial 1', 'Tutorial 2' and so on. When you wish to use a tutorial again it will then be easier to select the right tutorial. 2.1 CREATING A NEW SEWAGE WORKS</p> <p>'New Works' presents you with a blank drawing board, on which you can build up the description of your sewage works. From the Process Toolbox you can select which process you want to add to the drawing board. Having selected the process, and keeping the left mouse button depressed, move the icon onto the drawing board and position it where you want. Releasing the mouse button 'drops' the selected process onto the drawing board. You can repeat this for all the processes that you want.</p> <p>The Top Menu This is the drawing board</p> <p>The Processes Toolbox</p> <p>2</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>Every process has some stub lines marking influent and effluent connections, generally with influents on the left of the icon and effluents on the right. You connect the processes by placing the mouse pointer over the OUTPUT stub, when the pointer will change to a cross-hair symbol. Depending on the resolution of your screen, and the choice of mouse pointer colour, the cross-hair may appear as a cross-hair or as a fat cross; the fat cross may be coloured black or white. Pressing the left mouse button down, move the mouse to the INPUT stub on the process that you want to connect. When you are over the connection the pointer will change from a cross-hair to a 'chain-link'. Release the mouse button. The connection ('stream') between the two processes has now been established. To ensure that a connection has been made to each required stub, RIGHT click on the process and choose Connectivity from the menu which appears.</p> <p>Each stream must have a stream number assigned as in the screen shot above.</p> <p>If any stream name is blank at this point you must reconnect the stream to the process. This is shown in the above screen shot. If you have made a mistake you can select and then delete the stream by right-clicking on the stream; you can also delete processes in the same way. You do not have to complete putting all the processes in place before connecting processes; you can add processes and streams at any time. Having created your sewage works you will need to save the configuration before you can proceed any further. Select 'Save Works' from the 'File' menu.</p> <p>3</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>2.2</p> <p>RE-USING AN EXISTING SEWAGE WORKS</p> <p>Selecting 'File' and then 'Open Works' will present you with a list of existing works. (If nothing appears on the screen, then you have no works to choose from.) Select the works that you wish to use. On the screen will first appear the drawing board, and then the works layout will be drawn. If this is the works that you wish to model you can now select from the 'File' menu either to start a new run, or to complete an existing run. If you select 'Open run' you are presented with a list of all the runs that you have saved for that works. If a run has been completed you are not able to run it again, but you can view any of the data that was saved as part of the run. You can use this works as the base for a new works, deleting processes that you do not wish to study, and adding new processes. You must then save the results as a new works. There will now be no runs associated with the works all the runs having been associated with a works of different geometry. If you limit your changes to dimensions, keeping geometry the same, this is still treated as a new works. You will be asked to save the works before you can create any new runs, and you will have lost the initial conditions associated with the previous works. To keep the initial conditions of a previous run when you have only changed the dimensions of a works and had to save it as a New Works complete the following series of commands: Open Works New Run Save Works As Save Run As Select the works you wish to change Make the changes to the dimensions (not the geometry) Assign new name to the modified works Assign run name</p> <p>You will now have the new works with the modified dimensions but with the initial conditions from the previous Works. 2.3 CREATING A NEW RUN</p> <p>From the 'File' menu select 'New run'. If you have not correctly built the Works and are missing some streams you will be presented with the following error message depending on which process the fault is at. You should check the connectivity for the process and re-connect the streams as described in Section 2.1.</p> <p>Assuming the works has been correctly built, you will then be prompted for a name for the run, and what you want to use for initial conditions.</p> <p>4</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>There are three types of initial conditions that can be used in any run: 1. 2. 3. Specified by you (the cold start). Taken as the same initial conditions as used in a previous run (allowing you to carry out sensitivity or comparability studies). Use the end conditions from a previous run (allowing you to continue the simulation with calculated, rather than estimated, initial conditions).</p> <p>Following this you will be asked for details about the duration of the run.</p> <p>5</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>When specifying the simulation time the start time is fixed if you have chosen to use the initial conditions from a previous run. You can change the simulation length, specifying your required end time in DD/MM/YY HH:MM format. You will be warned if you have typed in an illegal date or time. The other piece of information you must supply is how frequently you want output. STOAT has no restrictions on the maximum output frequency but the default is 1 hour. You can also set other simulation parameters, such as the average sewage temperature (used by the activated sludge and biological filter models); the BOD equivalent of 1 g of biomass solids and volatile (but non-biomass) solids; and then numerical controls, such as the choice of integration method and accuracy. We recommend that you leave these as the default values, changing only the temperature. You can now set up the sewage works conditions for the run. You can do this for each process by right-clicking with the mouse on the process, where you will be offered a menu of the conditions that you can change. Changing any of the process data under 'Name and dimensions' defines a new sewage works. You can change any of the other data at the start of the run, and you can change any of the 'Operational' data during the course of the run, or program STOAT to have the changes made automatically for you. 2.4 SELECTING REPORTING OPTIONS</p> <p>By right-clicking on a STREAM you can select what you would like displayed.</p> <p>Select Reporting Options and the following screen is displayed:</p> <p>You can decide if you want data for the stream stored (Save Results) for future use, and if you want to look at the results as they are calculated ('In-simulation reporting'). If you want in-simulation reporting you can then select what components you would like to have displayed from the two options 'Simple determinands' and 'Advanced determinands'.</p> <p>6</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>Simple determinands are the common sewage components, while advanced gives you access to all the stream components in STOAT. You can select determinands from both the simple and advanced options, and they will all be displayed on the same graph. We recommend you do not choose to look at every determinand for every stream, as the result is more information than you can use during the simulation. Select a subset that represents where you expect to be interested. Because you can save the data for all the streams you can carry out a full post-mortem at the end of the run. You can also select how you want the results displayed from 'Report View. The default is as a graph, but you also have the option to have the results as a table, or as summary statistics (mean, maximum, minimum over the course of the simulation) or various combinations of these. Generally the most useful is the simple graphical display. You can change the report type during the simulation by selecting the report you want to change, then from the 'Window' menu selecting 'Display results as', which presents you with the same set of reporting types. Changing the display type during the simulation may corrupt the display. (Whether you get a corrupted display will depend primarily on the number of profiles that you have chosen to display.) You can easily fix this by minimising then restoring the display select the required window, double-click on the 'minimise' symbol (the downarrow in the top right-hand corner); then double-click on the minimised icon that will appear at the base of the STOAT window to restore the window, and clear any corruption of the display. 2.5 COMPLETING A RUN</p> <p>When you have entered all your data save the run. Then run the simulation. This ensures that should you have any problems during the run that you can start again. You start the run by selecting the 'Run' button symbol. You can pause the simulation with the 'Pause' button to make changes to the operational parameters, and then continue the simulation with 'Play. Selecting 'Stop' will stop the simulation you will not be able to continue afterwards with 'Play.</p> <p>Simulation start Simulation end</p> <p>Simulation time Elapsed tim</p> <p>Run name</p> <p>Run</p> <p>Stop Pause</p> <p>Progress monito</p> <p>When the run is finished, and assuming you are happy with the outcome, then again save the run. This preserves the results for you to examine later. If you are not happy with the outcome, or if STOAT encountered errors during the simulation, close the run from the 'File' menu and then open the run. Because you remembered to save the run before beginning the numerical calculations you can retrieve your starting point. Having done this you make whatever changes you feel are required, save the result, and then again begin to run the simulation. You can repeat this cycle until you are satisfied with the results, when you can then save the run. Once a completed run has been saved you can no longer make any changes to it. You can create a new run that will take either its initial conditions from either the initial or final conditions of previously completed runs.</p> <p>7</p> <p>WRc plc</p> <p>Tutorials Guide</p> <p>3.</p> <p>TUTORIAL 1: A SIMPLE WORKS</p> <p>This tutorial covers the modelling of a simple works comprising a sewage influent, primary tank and an activated sludge tank. 3.1 BUILDING A SIMPLE ACTIVATED SLUDGE WORKS</p> <p>Start by creating a new works. From the 'File' menu select...</p>