Approaches for Modeling Complex Processes through Integration of GoldSim and Specialized Supporting Models Ted Eary MWH Americas, Inc. Fort Collins, Colorado GoldSim 2007 User Conference, San Francisco

1. Submodel Abstraction & Incorporation 2. Independent Models linked through inputs and/or outputs 3. Direct Linkage Integration Approaches

Approach 1: Submodel Abstraction & Incorporation Output Input GoldSim Model Simplified Submodel ( Specific Process: solubility, reaction kinetics, runoff, infiltration, evaporation, …) Geochemistry Hydrology Limnology Climate etc… Specialized Supporting Models Data or abstracted submodel

Example: Water Treatment Plant Acid Water Neutralizers, flocculants, polishing agents, filtration, aeration, etc. Sludge Clean Water Problem: How much sludge will be produced?

Know: Sludge mass ≈ function(amount of chemicals added, time, pH, etc.) Solution: Develop submodels of specific processes from a combination of experimental data and theoretical calculations (e.g., supporting models). Create Lookup Table elements for GoldSim Approach for Submodel Incorporation pHFe mg/LAl, mg/LZn, mg/L E-028.6E E-023.0E E-031.3E E-032.0E-043.6E E-042.4E-043.0E E-046.7E-042.3E E-042.1E-032.3E E-046.6E-032.9E E-042.1E-028.5E E-046.6E-026.4E E-032.1E-016.3E-01 Gypsum Zinc Aluminum Iron

Solubilities are defined in the fluid properties element as Lookup Table functions, i.e., individual submodels. GoldSim Model of Water Treatment System

Some Results Total Sludge Lime Added Influent Effluent pH Lime Tank Aeration Tank Concentration, mg/L Time, days Tonnes

Submodel Abstraction & Incorporation Advantages Advantages Simple relationships focused on the most important processes Simple relationships focused on the most important processes Can use a combination of empirical and theoretical approaches Can use a combination of empirical and theoretical approaches Disadvantages Disadvantages Potentially limited range of applicability Potentially limited range of applicability Abstraction may make it difficult to understand relationships Abstraction may make it difficult to understand relationships

Approach 2: Independent Models Sequentially Linked through Inputs and/or Outputs Supporting Model (e.g., Geochemistry, Hydrology, Limnology, etc…) Input Output to Excel GoldSim Model Output (Excel) Input from Excel GoldSim Model Output (Excel) Input Supporting Model (e.g., Geochemistry, Hydrology, Limnology, etc…) Input Output

Example: Solution Mixing Chemistry Mixing and Reactions Alkaline pH, Clean water, Constant flow rate Acidic pH, High metal water, Runoff (variable flow rate) Problem: How to calculate solution chemistry after mixing and reactions?

Know: Mixed solution chemistry is a function(mixing proportions of two solutions – one acidic and one alkaline). Solution: Use the independent supporting model to calculate all possible outcomes and put the results in an Excel worksheet ( e.g., 1% acidic + 99%alkaline, 2% acidic + 98% alkaline, 3% acidic + 97% alkaline, etc……) Import the data from Excel into a Lookup Table element. Define an index in GoldSim to retrieve the appropriate mixed solution composition. Approach Specialized Supporting Model Main Model GoldSim (Water Balance) PHREEQC (chemistry) Output (Excel) Input from Excel

GoldSim Model (Details in next slide)

Chemistry Lookup Table (TableOfMixFractionChemistries) Species across Mixing Index down

Some Results Mixing Only Mixing and Reaction Al: Mixing Fe: Mixing Al: Mixing and Reaction Fe: Mixing and Reaction

Independent Models Advantages Advantages Easy to set up and runEasy to set up and run Leverage most of the capabilities of the independent supporting models with careful designLeverage most of the capabilities of the independent supporting models with careful design Disadvantages Disadvantages Limited to representing either the starting point or ending pointLimited to representing either the starting point or ending point Need to understand the system very well to make sure that the supporting model represents all possible inputs or outcomesNeed to understand the system very well to make sure that the supporting model represents all possible inputs or outcomes

Approach 3: Direct Linkage Input GoldSim Model Supporting Model (e.g., Geochemistry, Hydrology, GIS, Chemical Processing,…) Input Output Data transfer for every time step. Two approaches: Excel (Spreadsheet Element) Dynamic Link Library (External DLL Element)

DLL Data Flow Between GoldSim and the External Model GoldSim Model Supporting Model Output External DLL Element DLL Functions  Receive and format input data  Run Supporting Model  Get Output from Supporting Model  Return output to GoldSim Each time step External DLL Program

Same Example: Solution Mixing Chemistry Mixing and Reactions Alkaline pH, Clean water, Constant flow rate Acidic pH, High metal water, Runoff (variable flow rate) Problem: How to calculate solution chemistry after mixing and reactions? Solution: Use DLL to link to the PHREEQC geochemical model.

GoldSim Model DLL Element

Inside the DLL Interface tab Inputs to external DLL Outputs from external DLL

Some Results Mixing Only Mixing and Reaction Al: Mixing Fe: Mixing Al: Mixing and Reaction Fe: Mixing and Reaction

Direct Linkage through Dynamic Link Libraries (DLLs) Advantages Advantages Supporting model used each time stepSupporting model used each time step Leverage most of the capabilities of the independent supporting modelsLeverage most of the capabilities of the independent supporting models Disadvantages Disadvantages Execution time increasedExecution time increased Custom software code needed to construct the correct interface to the supporting modelCustom software code needed to construct the correct interface to the supporting model

Relative Speed (Solution Mixing, 5-year, 1-day time step) Mechanism GoldSim Execution Time Lookup Table 1-2 sec DLL – External Element 5 min 9 sec Excel-Spreadsheet Element 25 min 59 sec

Summary Many ways to model complex processes; Many ways to model complex processes; Advantages and disadvantages for each approach; and Advantages and disadvantages for each approach; and Choice of approach depends on the system simulated and goals of the model. Choice of approach depends on the system simulated and goals of the model.

Thanks Examples available for downloads: Model ID: 57 – Linking Geochemical Codes to GoldSim Model ID:69 - Simulation of Water Treatment for Acid Mine Drainage Model ID:70 - Calculating the Solubility Using Equilibrium Chemistry (Go Rockies Beat Red Sox) Early geochemists describe the first dirt molecule