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Welcome to the September 2008 Newsletter distributed by MOSTforWATER !
The Newsletter is aimed at:
sharing experiences in the use of WEST® as the prime tool for modeling and simulation in water quality
advertising the most recent developments in the software and the models as well as meetings, courses, conferences that may be of interest for WEST® users.
"I see this Newsletter as a way to boost communication amongst WEST® users, directly through professional and academic links.
It is also an opportunity for me to stress that MOSTforWATER offers consultancy to maximize your results and reduce your modeling efforts in order to achieve your objectives (meeting standards at minimal total costs)."
(Dirk Van der Stede, CEO - director)
GENERAL INFORMATION
EVENTS
TECHNICAL ARTICLES
Simple user interfaces for complex wastewater treatment simulators
A dynamic model of the Lethabo cooling circuit
NEWS FROM SCIENTIFIC SUPPORT CENTERS
Course of wastewater engineering at TU Berlin
MSc dissertation at UKZN
PRODUCT INFORMATION
New MBR model
User tips: continuity check
GENERAL INFORMATION
- Website
In developing WEST® and customers communication, all care has been put into ensuring that users receive sufficient information to enable them to obtain the most out of their dynamic modeling and simulation exercise.
In this context, the FAQ section of the MOSTforWATER website plays an important role and has received a make-over and now contains several items categorized as follows:
- About MOSTforWATER: provides general information on the company and the services that you can request.
- Installation: discusses installation issues.
- Documentation: explains where you can find extensive documentation on the use of WEST.
- Software: contains a list of general questions that users often seem to be struggling with and of common error messages that may be displayed.
- Modeling: addresses specific modeling issues that are not related to a specific software.
These categories summarize the most relevant support issues that WEST® users have addressed to us in the last months and will therefore be a valuable source of information for basic (and for some advanced) troubleshooting.
Please, always check the FAQ’s if you have questions regarding the use of WEST®: should you not find a satisfying answer, do not hesitate to address your questions to our Customer Support.
- Welcome to Lorenzo Benedetti
We gladly announce that Lorenzo Benedetti joined the MOSTforWATER team!
Lorenzo received his MSc in Environmental Engineering in 1999 at the University of Florence (Italy) with a thesis on a case study of WWTP and river models integration.
He then worked for three years as a consultant in Italy and abroad (for UN programs) on several water-related issues. In 2003 he joined the BIOMATH research group at Ghent University (Belgium) to receive in 2006 a PhD under the supervision of Prof. Peter Vanrolleghem, dealing with WWTP design and upgrade, real time control, uncertainty assessment and integrated urban water system modeling.
At MOSTforWATER, Lorenzo will primarily help in developing and applying the tools, methods and consultancy used in integrated modeling and uncertainty analysis. He will still conduct scientific research at Ghent University and at the Technical University of Denmark (DTU) in Copenhagen.
- New generation of WEST®
MOSTforWATER is very excited to announce the new generation of the WEST® Product Suite. This new release that will be launched in November 2008 combines the state-of-the-art software technology with ease of use.
The new product suite is user-oriented and has been devised to meet the specific user requirements.
- WESTforDESIGN
Advanced dynamic modeling and simulation to enhance your design process
- WESTforOPERATORS
Easy-to-use dynamic modeling and simulation to assist your operational decisions
- WESTforOPTIMIZATION
Cutting edge dynamic modeling and simulation to support your process optimization efforts
- WESTforAUTOMATION
Seamless integration of dynamic modeling and simulation in your process automation applications
- WESTforIUWS
Powerful dynamic modeling and simulation for your Integrated Urban Water Systems
The overall concept remains "write once, run anywhere" (WORA): so each stage from design to operation, process optimization, upgrading and automation can use the results of previous modeling steps.
- New Head of BIOMATH (Ghent, University)
As of October 1st 2008, Dr Ingmar Nopens will be in charge of the BIOMATH research group at Ghent University.
Dr Nopens holds a MSc in Bio-engineering (1999) and a PhD in Applied Biological Sciences - Environmental Technology (2005), both obtained at Ghent University.
During his MSc, he worked on the combined respirometric-titrimetric model and set-up for improved parameter estimation of respirometric experimental datasets.
For his PhD, he focused on the development of the Population Balance Model (PBM) framework for biological applications, being activated sludge flocculation.
During a subsequent three year post-doc at BIOMATH, he worked on several topics. Core focus was on the integration of PBM in computational fluid dynamics (CFD) for both settlers and membrane bioreactors (MBR). Next to this, he was, among other things, involved in developing biological and filtration models for MBR, PBM-CFD modeling of anaerobic MBR, finalization of the Benchmark Simulation Model nr.2 (BSM2) and more specifically the model interfaces and ring testing, development of a sand filtration model, model calibration of full-scale treatment plants, etc.
All the aforementioned has equipped him with sound knowledge on both the methodological and application-oriented aspects of model-based bioprocess analysis and optimization.
The mission of BIOMATH, i.e. "Model-based bioprocess analysis and optimisation" will be maintained, however, the emphasis of the research might shift in the future as current projects fade out and new projects are started up.
EVENTS
The following events took place since the previous Newsletter was released.
- WEST® training course (5-6 May 2008, Gent, Belgium)
The "Introduction to model-based optimization of wastewater treatment plants" course was held at BIOMATH (Ghent University).
It targeted WEST® users with no or little experience of the software, and potential customers, such as engineering companies in the field of wastewater and sanitation that may be interested in learning about the capabilities of WEST®.
Participants (consultants and academics from Europe and China) appreciated mostly the practical exercises, on dynamic simulations, scenario analysis and model calibration, that complemented the first half-day of theoretical explanations.
The following topics were covered: guidelines for WWTP modeling; dynamic simulation (with exercises); scenario analysis (with exercises); model calibration (with exercises); case studies: model-based optimization and model calibration of WWTPs.
Similar courses will be offered in the future on a regular basis.
Should your Company or University be interested in a WEST® training program, please contact us and we will assist you.
- 1st IWA/WEF wastewater modeling seminar (1-3 June 2008, Mont Sainte-Anne, Canada)
This conference was the ideal successor of the Kollekolle (Denmark) seminars, the first one presenting the ASM1 model in 1985 and the last one being in 2001.
It was organized by modelEAU, a research team within the Civil Engineering department of the Université Laval (Québec, Canada) which is focused on development and use of quantitative, model-based methodologies.
The conference had a quite unusual format which in fact proved very effective:
- it was limited to 120 invited people, 85 % of which actively contributed to its preparation;
- it was focused on developing new ideas and generating consensus, with 10 workshops, 8 break-out sessions and ‘only’ 12 oral presentations, with lots of discussion time;
- it favored a mix of academics, consultants, software and equipment suppliers and plant operators;
- it succeeded in the ambition to bring North-American and European experts together.
The first day, Sunday, the attendees were evenly assigned to workshops, in which a chairman shortly introduced the topic and the rest of the time was allocated to an open discussion: the outcome of each workshop was then presented to the rest of the audience in Monday’s plenary session.
The following workshops were organized: Modeling accuracy - dealing with uncertainties; Recent advances in clarifier modeling; Anaerobic digestion modeling - current practice and areas for development; Integrating biofilm models into whole wastewater treatment plant simulators - expectations, applicability, accuracy and future improvements; Towards practical guidance for wastewater treatment modeling studies - draft guidelines from the IWA Good Modelling Practice Task Group; Models in teaching and training; Towards commonality in wastewater characterization for activated sludge modeling; Challenges in membrane bioreactor modeling; Use of plant-wide models in WWTP design - from steady-state to dynamic models; Experience with models and knowledge-based systems for plant operations.
Two major groups of topics emerged from the seminar:
- new model extensions and modeling concepts, i.e. metabolic modeling and multi-step nitrification/denitrification process modeling
- good modeling practice, specifically the use of existing models in consultancy, teaching and training.
Eight break-out sessions were organized in which smaller groups of particularly motivated people met to discuss topics raised during the seminar.
The following topics were discussed: Micropollutants; Endogenous processes; Greenhouse gas generation; Particle size modeling in clarifiers and membrane systems; Updating model nomenclature; Chemical and biological phosphorus removal; and The use of on-line data for model calibration.
with other organizations, such as Black&Veatch, CDM, CH2M-Hill, MWH and VEOLIA.
The next WWTmod conference is already being prepared and will take place around March 2010.
- MBR Summer School (15-17 July 2008, Ghent, Belgium)
The Summer School on Modelling Membrane Bioreactor Processes was hosted at Ghent University under the organization of BIOMATH and supported by the Marie Curie Early Stage Research Training Project MBR-Train financed by the European Commission.
35 participants, mainly PhD students from 16 different countries and four continents attended the summer school providing an excellent platform for networking besides acquiring a deeper knowledge of different aspects of MBR modeling.
Among the topics that were highlighted were basic and advanced biological process modeling of MBR and introduction to data acquisition, process control, computational fluid dynamics (CFD) and population balance models (PBM). Some practical CFD applications for MBR were given as well.
In addition, hands-on exercises with the latest available biological and filtration models using the modeling and simulation platform WEST® allowed the participants to apply the acquired knowledge to a practical case.
The event was closed with a half day technical visit to the full scale MBR wastewater treatment plant Schilde operated by Aquafin.
The following events are scheduled for the upcoming months.
TECHNICAL ARTICLES
Every issue of the Newsletter will give visibility, within the WEST® community, to some interesting scientific and technical work that involved the use of WEST®.
It is not the intention to set high standards in terms of scientific content of the articles: the main objective is to prove the flexibility and wide range of possible applications of WEST®.
Every issue will present "technical communications" prepared by WEST® users: so you are invited to submit your contribution as well as your remarks and suggestions to make this initiative effective for the largest portion of WEST® users possible.
Simple user interfaces for complex wastewater treatment simulators [download pdf]
by: C. Lilburne, M. Burns, D. Batstone, S. Stevenson, S. Jennings and K. O’Halloran (Australia)
The Advanced Water Management Centre ( AWMC) at The University of Queensland is currently working with Gold Coast Water (Queensland, Australia) to produce WEST-based custom applications for simulation of their wastewater treatment plants. One of the major projects is a training interface, consisting of a Visual Basic front end, using the WEST® API (application programming interface) to link to a WEST® model.
Key outputs and controls can be accessed and displayed in a similar manner to that which is displayed on a plants SCADA system, and much of the models complexity is hidden, providing a realistic, but accessible simulator, suitable for operators to use.
This paper illustrates the application to the Beenleigh Wastewater Treatment Plant (Beenleigh, 4207, Brisbane, Australia).
PROCESS DESCRIPTION AND MODEL
This plant has classically been a challenge to operate, due to highly variable loading, strict license limits and a substantial contribution from industrial sources. It is designed for a load of 60,000 person equivalents and currently operates at approximately 90% capacity.
Although it is designed as a Bio-Denipho system, it is currently operated with the two ditches in series (as opposed to parallel). The first ditch, which is preceded by an anaerobic zone, is operated largely aerobically and is aerated by brush surface aerators. The second ditch is predominantly an anoxic fraction.
The complex underlying model was developed by M. Burns and D. Batstone in WEST® and is based on the standard ASM2D which includes phosphorus removal.
THE INTERFACE
The current interface (programmed in Citect) allows operators to monitor the plant in real-time, view historical data and make changes to the way the plant operates. Specifically, for the bioreactor section, operators are given a stylised ‘birds-eye-view’ of the two ditches ( Figure 1) and are able to view the temperature, pH and dissolved oxygen readings at various points (corresponding to the location of sensors), as well as online ammonia, nitrate and phosphorus concentrations in the effluent.
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Figure 1 - Beenleigh WWTP current CITECT control system.
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The interface has two main purposes: to control the simulation and to gather and present data from the simulation. Controlling the simulation involves starting and stopping the simulation, and changing inputs (including control system set-points) while the simulation is running. Gathering data means repeatedly reading the current variable values (DO, TSS, VSS etc), storing them and presenting them on the screen as graphs or numerical values when required. Operational staff can then use these “what if” scenarios to predict potentially variable influent quality on process performance. This in turn allows them to respond with key operational control measures to counter the predicted impact, hence increasing their knowledge of control options under varying circumstances.
In the first ditch, each aerator can be individually set to ‘always on’, ‘always off’ or to ‘control’. In the latter mode, the aerators will be turned on or off based on the dissolved oxygen concentrations measured in the ditch. There are rules in place which dictate the order in which the control system will activate or shutdown the aerators. Different DO set-point limits are implemented throughout the day to cope with different diurnal loads on the plant.
Figure 2 shows the start-up screen that users see when the program opens.
Conceivably, any parameters or variables included in the model can be accessed through the WEST® API and changed using the interface, and the data being displayed is not limited to what is normally available to operators, which also aid in understanding the process and the plant.
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Figure 2 - Overview of the training interface.
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CONCLUSIONS
Initial response from the operators has been very positive, with strong recognition of the key outputs, and informed feedback, without substantial explanation of the design. On-going work is focusing on finalizing the interface, attempting to calibrate the underlying model to current operations, and will assess whether the operators can use the model to gain some more value in excess of their already extensive experience.
For those operational staff that are relatively new to the industry or a particular plant, this tool, may accelerate their learning curve by exposing them to a wide variety of potential operating scenarios that otherwise they may only be exposed to over a longer period of time.
A dynamic model of the Lethabo cooling circuit [download pdf]
by: R. Jean, C.J. Brouckaert and C. A Buckley (South Africa)
The Lethabo Power Station, situated near Vereeniging in South Africa has a generating capacity of 3600 MW. It is one of 13 coal-fired power stations operated by ESKOM, the South African power utility. Most of these are open evaporative cooling systems in which cooling water that is passed through the steam condensers system discharges heat to the environment via evaporative cooling towers. To minimize water consumption, the cooled water is recirculated, however this leads to a concentration of dissolved impurities in the circulating water. The Lethabo cooling circuit typically takes in about 140 ML/d, of which 120 ML/d is evaporated; the remaining 20 ML/d is disposed of by spraying onto the coal ash heaps.
In a situation with a varying circulating flow rate and make-up water flow, the operator of a cooling system has to deal with two major problems:
- Scale formation, caused by the increased concentrations and the rise in temperature of the cooling water as it passes through the heat exchange equipment.
- Corrosion of the metal surfaces of the heat exchange equipment.
Avoiding these problems requires careful management of the water chemistry in the circuit. The main instruments employed for this purpose are lime softening (precipitation of calcium carbonate and magnesium hydroxide) and reverse osmosis.
The system is large and dynamic, affected by the power demand and weather conditions. The power station is associated with an open cast coal mine on its boundary which supplied the coal, and uses the cooling circuit to dispose of contaminated mine water in order to protect the environment, which adds to the complexity of the water management.
The Pollution Research Group at the University of kwaZulu-Natal was commissioned by ESKOM to develop a model of the cooling water circuits to help in addressing some of these problems.
At this time the project has reached point where a prototype model has been developed and tested against data gathered over a period of a month. It is planned to use the model initially as a training tool for operators, to help them understand the complex interactions which occur in the circuit, and then, as experience is gained in its use, to extend it to problem solving investigations, and possibly even online monitoring. However using it online will require a major upgrade to the plant instrumentation, so this is still a remote prospect.
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Figure 3 - Schematic diagram of the Lethabo Power station.
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A mathematical model with the following features was developed in WEST®:
1. A chemical speciation model which represents the main inorganic ionic species found in cooling water, and their reactions. The ionic components included are H+, Na+, Ca++, Mg++, OH-,CO3=, HCO3-, Cl-, and SO4=. The reactions between these components that are represented are ionic equilibria (including calculation of pH and alkalinity), precipitation of CaCO3 and Mg(OH)2, and CO2 exchange with the atmosphere. At present complexation by organics has not been included, because of lack of reliable data to base the model on.
2. A mass balance model which considers the flow rates and compositions of water entering the cooling circuit, together with evaporation and water treatment processes, to simulate the evolution of the cooling circuit chemistry with time.
The model was validated and calibrated in two main steps:
- The chemistry model was validated by comparing its outputs with those of the US EPA speciation program MINTEQA2 using analytic data from the Lethabo cooling circuit as input.
- The complete flow and chemistry model was run using as input a month’s record of operating data (December 2003) for the circuit.
THE CHEMICAL MODEL
The chemical reactions are divided into two groups, the extremely fast aqueous phase ionic reactions, and the relatively slow interphase reactions, which consist of solid precipitation/dissolution reactions and absorbtion/desorbtion of gaseous CO2. To avoid the problems of a stiff set of differential equations, the fast ionic reactions are modeled using an algebraic equilibrium formulation in an external subroutine, while the interphase reactions are modeled using a standard WEST® kinetic formulation ( Figure 4).
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Figure 4 - The chemical model.
Note that only a small portion of the aqueous carbon dioxide exists as carbonic acid (less than 0.3% at 25°C): then we define H2CO30 as = CO2(aq) + H2CO3.
Gas concentrations are given as partial pressure; e.g. atmospheric PCO2 = 10-3.5)
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For the fast aqueous ionic reactions, the mass balance components are Haq, Mgaq, Caaq, CO3aq, and SO4aq (total concentrations of the relevant components). The WEST® solver keeps track of the 5 mass balance components Haq, Mgaq, Caaq, CO3aq, and SO4aq, i.e. they are regarded as species by WEST®. At each time step, their values are passed to the subroutine which solves iteratively for the ionic species the equilibrium relationships. All the ionic concentrations are then returned to the solver as algebraic variables.
The chemistry model has ‘switches’ which allow certain reactions (precipitation, carbon dioxide exchange with the atmosphere) to be allowed or disallowed.
INPUT PREPROCESSOR
The use of total concentrations as state variables, particularly in the case of Haq and CO3aq, presents a practical problem in that the laboratory water analyses that provide input data do not measure these directly. Instead, pH and alkalinity are determined. To convert the laboratory analyses into variables which can be input to the model, the chemical speciation model has to be run in reverse.
The problem is complicated by the fact that any precipitated carbonates present in a water sample will re-dissolve during the alkalinity titration, and contribute to the alkalinity value. To assist the preparation of input files for the model, a pre-processor has been developed which uses a constrained regression procedure to find a set of total ionic concentrations which most closely matches the laboratory analysis. The constraint that has to be met is the overall electroneutrality of the solution.
UNIT OPERATION MODELS
Most of the cooling circuit can be represented using standard WEST® unit operation models: mixed reactors, buffer tanks, splitters and combiners.
However three new unit operations were required: the cooling tower, the reverse osmosis plant and the ‘mixing unit’ ( Figure 5).
The cooling tower and the reverse osmosis units were modeled very simply as mass balance units (plus an energy balance for the cooling tower) using performance coefficients based on historical plant data.
Thus the cooling tower model has an evaporation rate and wind drift loss rate related to the power generation load, and the reverse osmosis model has salt rejection and water recovery coefficients based on measured performance data.
The mixing unit was modeled as completely mixed tank and used for the CO2 exchange, precipitation and condenser units (visible in Figure 5).
All the other units are standard, including valves and controllers - with minor adjustments to accommodate the new model category.
The main elements that are being regulated are the fraction of the circulating water load which goes through the treatment plant and the lime dose, to control pH and alkalinity. There is also a controller for the pH of the water fed to the reverse osmosis plant, and for the makeup of fresh water to the circuit.
THE IMMEDIATE FUTURE
The next step that is planned is to hold a workshop with ESKOM personnel to establish in greater detail how they intend to use the model in the initial phase as a training tool, and how it should be adapted to best suit their requirements.
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Figure 5 - WEST® configuration of the prototype model.
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NEWS FROM SCIENTIFIC SUPPORT CENTERS
The WEST® Scientific Support Centers (SSC) are constantly not only using WEST® in various applications but also striving to improve its capabilities, to extend the model library, to disseminate the knowledge of WEST® among students and engineers.
Wastewater Engineering Course at TU Berlin
For the past three years, the undergraduate course in "Wastewater Engineering" at the department department of Environmental Process Engineering of the Technical University of Berlin (Germany) has been complemented with a combined laboratory and computer simulation course, in which approximately 30 students each year are taught not only classical plant design, but also biological and physical reaction kinetics through the aid of dynamic simulations.
The software in use is WEST®.
Starting with an empty Petersen matrix, a reaction model for hetero- and autotrophic biomass growth, endogenous respiration and decay is implemented step-by-step. Aeration kinetics are introduced alongside and apportioned to fine tune the mass transfer coefficient for changing airflows.
With the implemented reaction model, the students will have to:
- build a virtual plant and run dynamic simulations under changing influent conditions
- identify the limiting parameters for insufficient effluent concentrations
- develop an optimal plant design, by looking at tank volumes and operational costs.
The next step is the examination of activated sludge from a local WWTP of Berlin in a laboratory-scale reactor. Several parameters are measured over a long period of time and especially the oxygen consumption is examined during outgassing experiments.
These experiments are then simulated in WEST®.
The last step is the discussion of made assumptions during the model built-up and the application of the simulation results on the real WWTP.
MSc Dissertation at UKZN
A dissertation entitled "Modeling of the Marianridge Wastewater Treatment Plant" was submitted by Mr F.T.Mhlanga for the MSc Eng degree in Chemical Engineering at the University of kwaZulu-Natal.
In the framework of a larger project aimed at investigating the impact of industrial effluents on activated sludge wastewater facilities in the Greater Durban Area (South Africa), he set up a mathematical model (based on the ASM3) of the small Marianridge WWTP which treats an average flow rate of 8,000 m3/d of mixed municipal and industrial (30 %) wastewater containing a large proportion of textile effluent.
WEST® was essentially used to calibrate the parameters of the ASM3 in two stages: first, a parameter optimization was carried out to fit the results of laboratory-scale respirometric tests; then, a sensitivity analysis and subsequent parameter estimation were carried out to fit historical data on COD and ammonia.
The model will be used (probably with some modification) as a platform to evaluate the impact of effluents from specific factories on the plant’s ability to treat the mixed wastewater to meet the requirements for discharge to the environment. This information is intended to guide the specification of effluent discharge permit conditions for the factories.
PRODUCT INFORMATION
This section of the Newsletter is intended to address practical issues in the use of WEST®. In every issue, new models will be illustrated, advances in the software discussed and small technical topics discussed that may have been object of frequent questions by the users.
New MBR model
In the context of a recent MBR Summer School organized by BIOMATH (Ghent University), a practical case-study was worked out and the standard WEST® 3.7.5 modelbase slightly extended to allow for some advanced simulation for this MBR plant.
A basic MBR configuration consists of an MBR unit and a buffer tank - this latter provides the storage capacity for the permeate that has to be used as backwashing liquid.
Firstly, a new model for a pump-controlled buffer tank was added to the modelbase.
The base in which the outflow is controlled by a pump was therefore modified to accommodate a second outflow to mimic the backwash flow. This second outflow can be controlled externally.
With this first modification, it was possible to set up a steady-state simulation, i.e. in which the membrane surface (which is otherwise a function of the desired permeate flow rate, hence of the influent flow rate) is constant throughout the simulation.
A second modification was necessary, to allow for describing a commonly used strategy in which the membrane surface can adapt to the flow rate being treated (in practice, modules are taken in or out of operation) and therefore to allow for dynamic simulations. A new model for a controller was added to the modelbase whereby the output is converted to the output via a linear transformation.
This is evidently not a very realistic controller for this type of application, since in the practice the membrane surface changes discontinuously, due to membrane modules being turned on or off.
The model however proved sufficient to demonstrate the applicability of the WEST® MBR model to a realistic scenario ( Figure 6).
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Figure 6 - Dynamic simulation with the WEST® MBR model (the configuration in the inset).
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User tips: continuity check
The continuity check is a valuable tool for model verification, whereby the conservation of elemental components, electrons (or COD) and net electrical charges is verified.
where:
vij denotes the stoichiometric coefficient for the model component i in the process j
fci is the conversion factor between the model component i and the element c
N is the number of model components for the specific category.
The set of conversion factors (collectively termed continuity matrix) is calculated stoichiometrically. For instance, the conversion factor of nitrate to COD is:
based on the following stoichiometry
For the standard categories of the WEST® modelbase, the following "elements" are pre-defined: COD, nitrogen (N), phosphorus (P), net electric charge (Charge), mass of the total suspended solids (TSS) and theoretical oxygen demand (ThOD).
Elements can be defined by the user and processes can be selectively included in the computation.
The objective of a continuity check is that all continuity equations be zero for all elements: values greater or smaller than zero for a given element would indicate that the element be formed or destroyed which in turns would suggest an error in the implementation of the biochemical system (unless some components are taken into account implicitly).
STEP-BY-STEP PROCEDURE
- Go to the Petersen Matrix editor (within the Model Editor tool)
- In the Matrix menu, select the Continuity Check Settings option: the corresponding dialog will pop up:
- The Factors tab is a visual representation of the continuity matrix, in which Elements can be added or removed (through the corresponding buttons in the toolbar) and enabled or disabled for the calculation
- A continuity factor is required for every element included in the calculation and for each model component. The factors may be selected from the list of model parameters (through the drop-down menu) or by entering a number (Figure 7)
- A continuity matrix can be imported from an existing .wcf file. The continuity matrices for all the base categories (ASM1, ASM2, ASM3 and ASM3P_EAWAG) are provided in the standard model library:
C:\Documents and Settings\...\ContinuityCheck\
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Figure 7 - Continuity check settings.
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- The Calculation tab allows the user to specify the precision (interval around the zero) for the continuity calculation and to enable or disable a process for the calculation
- The settings can be saved in a .wcf file or simply confirmed, by pressing the OK button
- To run the continuity check, press the Continuity Check button on the toolbar.
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