Phreeqc is a software developed by the USGS written in C++ capable of modeling a variety of aqueous geochemical processes such as mixing of waters, modeling equilibrium between solid and aqueous phase, modeling impact of temperature, calculation of element concentration among others.
Hatarilabs has developed an applied and unique course of Phreeqc integrated with an online platform Aquifer App that can run, parse and provide Phreeqc output as tables and figures. The platform also allows exporting model data for further analysis with other Python libraries on a Jupyter notebook. The course also offers a brief explanation of the most common Phreeqc keywords when they are implemented on the simulations.
Trainer
Saul Montoya M.Sc.
Saul Montoya M.Sc. is a Hydrogeologist and Numerical Modeler. Mr. Montoya is a Civil Engineer graduated from the Catholic University in Lima with postgraduate studies in Management and Engineering of Water Resources (WAREM Program) from Stuttgart University – Germany with mention in Groundwater Engineering and Hydroinformatics. Mr Montoya has a strong analytical capacity for the interpretation, conceptualization and modeling of the surface and underground water cycle and their interaction.
He is in charge of numerical modeling for contaminant transport and remediation systems of contaminated sites. Inside his hydrological and hydrogeological investigations Mr. Montoya has developed a holistic comprehension of the water cycle, understanding and quantifying the main hydrological dynamic process of precipitation, runoff, evaporation and recharge to the groundwater system.
Over the last 9 years Saul has developed 2 websites for knowledge sharing in water resources: www.gidahatari.com (Spanish) and www.hatarilabs.com (English) that have become relevant due to its applied tutorials on groundwater modeling, spatial analysis and computational fluid mechanics.
This example covers the simulation of the distribution of species in seawater and the saturation of a set of minerals. In order to demonstrate the capabilities of Phreeqc to simulate new elements, uranium is added to the solution by specifying keywords and with the use of the wateq4f database. The example cover all these cases:Speciate seawater specifying redox reactions.Speciate seawater with calculation of density and pe.Speciate seawater with uranium in the solution and defining phases.Speciate seawater with uranium using the Water4f database.
This session covers two exercises on geochemical modeling:An applied example of chemical speciation modeling in Aquifer App of brines from a salt lake on the Tibetan Plateau in China that has Lithium in concentrations close to 250 mg.The second example covers the solubility of gypsum and anhydrite related to temperature. Concentrations and saturation indexes are analyzed for batch reactions in Aquifer App, to analyze the trend of saturation indices for given phases a Python script is performed from the downloaded data.
Examples that show the Phreeqc capabilities to mix water from different origins. In this session we will cover two applied examples of groundwater mixing with surface water.An example of freshwater mixing with seawater for the Biscayne Aquifer, Florida, USA on equal parts and the original and final concentrations and saturations are analyzed with Aquifer App.Example that shows the mixing of pure water in equilibrium with calcite and co2 that is mixed with seawater. Mixing is specified as percentages and the resulting solution is then equilibrated with calcite and dolomite.
Irreversible reactions can be simulated on Phreeqc through the REACTION keyword. This session develop two applied examples of irreversible reactions:Simulation of reactive barriers of elemental iron to reduce groundwater constituents in-situ. Comparison among the element molalities and the precipitated phases along the different reactions.Applied example of Phreeqc for the simulation of irreversible reactions in the oxidation of pyrite. Pyrite, calcite, and goethite are allowed to dissolve in equilibrium and partial pressure of CO2 is maintained at 10E-3.5. Two species: O2 and NaCl are added into the solution in five different relative proportions of a given concentration.
This session covers two types of geochemical simulation: sorption and reaction kinetics. These simulation are implemented with the EXCHANGE and KINETICS keywords.The first example uses the cation ion exchange approach where only the EXCHANGE keyword is used because EXCHANGE_MASTER_SPECIES and EXCHANGE_SPECIES are included in WATEQ4F.dat database. The model output is downloaded as csv files and the solution composition and description are calculated and compared before and after the exchange.The second example shows the use of reaction kinetics for the time dependent calcite dissolution where reaction rates are given by a small BASIC program. The example defines a Python function that lists the molarity and saturation of Calcite and plots those values for the different times defined as batch reactions.
This session will cover two applied cases of geochemical modeling with Phreeqc and Aquifer App.The first example covers the water treatment of a sulfur spring with concentration of 16.67 mg/L that is equilibrium with O2 and can precipitate aluminum hydroxide and iron hydroxide. Comparison of the initial and final sulfur concentrations as well as the related phases are analyzed through Aquifer App.The last example covers the case of nitrate reduction with methanol. A solution with nitrite concentration of 100 mg/L is reacted by adding different molalities of methanol from 0.1 to 100 mmol. Nitrite concentrations are explored on Aquifer App and further nitrate concentration vs methanol plots are developed with Python scripts.
