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Project title:


Thermodynamic assessment of the ecological impact of excess nitrogen and phosphorus in recreational water bodies supplemented by reclaimed water


Project leader:


Luo Li


Reclaimed water use for the supplementation of a water body potentially increases the problem of eutrophication caused by excess nutrient. The occurrence of eutrophication is influenced by many factors. Thus, quantitative evaluation of the ecological impact of nutrients is faced with many problems. Based on the idea that the ecological impact of any contamination is the state change of the thermodynamic equilibrium of a water system from, this project studied the thermodynamic assessment of the ecological impact of excess nutrients. By studying the processes involved in the conversion of nitrogen and uptake of phosphorus by typical algae in the water body, the principle of the conversion of nutrients to biomass was identified. Consequently, a model of algae growth was proposed. For analysis of photosynthesis and energy transformation processes of a typical algae growth cycle, the biomass energy storage characteristics of algae cells were revealed. A model for the calculation of energy consumption for algae growth was established. Afterward, by studying the thermodynamic characteristics and principle of entropy balance of algae growth, a method for the calculation of entropy increase under conditions of nitrogen and phosphorus limitations were proposed. Finally, combined with the process analysis of a water body supplemented by reclaimed water, a model for thermodynamic assessment was established, which was applied and verified. The results provide new approaches and methodologies for environmental impact assessment and regulation of the ecological utilization of reclaimed water.