Simulation study on algal dynamics under different hydrodynamic conditions

Algae growth is affected by both their physiological characteristics and the external driving factors, including light, temperature and nutrients. The nutrients released from sediment resuspension under hydrodynamic forces, impose significant effects on algae growth. In this study, an experiment of Taihu algal dynamics under different simulated hydrodynamic conditions was carried out in an ecologic tank. The experiment was conducted using water and sediments collected from Taihu under three different hydrodynamic conditions: static, slow water flow, and fast water flow. Based on the experimental data, an algal growth model was developed using the PHREEQC simulating package and incorporating observed biochemical and ecological kinetics. Quantitative relations between the releases of nitrogen/phosphorus nutrients and the water flow velocity were incorporated in the model based on the results from laboratory experiments of nutrient release from sediments in an annular tank. Detailed calibration and verification of the model parameters were carried out based on the experimental results. The calculated values fitted well with the data, suggesting that the developed model represents the dynamic growth of algae reasonably well. This model may be used to study the mechanisms of algae bloom in Taihu.