Simulating pH effects in an algal‐growth hydrodynamics model1 |
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Authors: | Scott C. James Vijayasarathi Janardhanam David T. Hanson |
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Affiliation: | 1. Sandia National Laboratories, Thermal/Fluid Science and Engineering, , Livermore, CA, 94551‐0969 USA;2. Exponent Inc., , Irvine, California, 92618 USA;3. Department of Physics & Astronomy, University of New Mexico, , Albuquerque, New Mexico, 87131‐0001 USA;4. Department of Biology, University of New Mexico, , Albuquerque, New Mexico, 87131‐0001 USA |
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Abstract: | Models and numerical simulations are relatively inexpensive tools that can be used to enhance economic competitiveness through operation and system optimization to minimize energy and resource consumption, while maximizing algal oil yield. This work uses modified versions of the U.S. Environmental Protection Agency's Environmental Fluid Dynamics Code (EFDC) in conjunction with the U.S. Army Corp of Engineers' water‐quality code (CE‐QUAL) to simulate flow hydrodynamics coupled to algal growth kinetics. The model allows the flexibility of manipulating a host of variables associated with algal growth such as temperature, light intensity, and nutrient availability. pH of the medium is a newly added operational parameter governing algal growth that affects algal photosynthesis, differential availability of inorganic forms of carbon, enzyme activity in algae cell walls, and oil production rates. A single‐layer algal‐growth/hydrodynamic model without pH limitation was verified by comparing solution curves of algal biomass and phosphorus concentrations to an analytical solution. Media pH, now included in the model as a growth‐limiting factor, can be entered as a measured value or calculated based on CO2 concentrations. Upon adding the ability to limit growth due to pH, physically reasonable results have been obtained from the model both with and without pH limitation. When the model was used to simulate algal growth from a pond experiment in the greenhouse, a least‐squares fitting technique yielded a maximum algal production (subsequently modulated by limitation factors) of 1.05 d?1. Overall, the measured and simulated biomass concentrations in the greenhouse pond were in close agreement. |
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Keywords: | biofuels CE‐QUAL CO2 EFDC modeling algae growth pH effects |
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