Water Quality Modeling Using For Algae Bloom Control In Wujiang River System-China

This thesis explores a specific environmental issue that often accompanies rapid economic developments, namely nutrient over-enrichment problem - also referred to as eutrophication. It more specifically focuses on studies and analyses of water quality modeling in the Wujiang river system, which has itself been facing eutrophication problems. The author examines the causes and effects of eutrophication on the water environment and analyzes different cases in which various methods were employed successfully or unsuccessfully to mitigate such a problem. This analysis is done so as to provide realistic alternatives in the management of rehabilitation programs for water systems.In order to do so, the author proceeded with the following methodology. First, an analysis of water quality simulation (WASP5) was conducted on the main pollutants (NH3-N and CODcr) in the Wujiang River system. Then, a detailed framework of the hydrodynamics and the water quality was conducted. The thesis emphasizes the most efficient ways to prevent eutrophication. One of them is the reduction of effluent pollutant load from wastewater plant and runoff from agriculture and communities in order to meet the concentration level III, as prescribed by Chinese authorities. With these levels of concentrations, a percentage of reduction was estimated at 40% and 75% for COD_Cr and NH₃-N respectively.After having performed the water quality simulation and established the quantity of pollutant reduction required, this thesis assesses potential solutions to reduce the predominant pollutant in the Wujiang River system, namely NH₃-N - since N represents the main factor affecting the growth of algae. However, the author also took into account that, in addition to high levels of NH₃-N, current effluent from PS of pollution are other major factors that tend to exacerbate problems of eutrophication in the Wujiang river system - specifically the propagation of algae bloom populations. Based on these findings and considerations, this paper briefly discusses some examples of physical, biological, and chemical techniques that have been employed for algal bloom control in water bodies and that could potentially be used in the context of the Wujiang River system. Thus, the author suggests some measures such as biomanipulation (internal control) and-artificial wetland (external control) as suitable techniques to address the problem of algal bloom control in the Wujiang river system.