An optimization model of sewage discharge in an urban wetland based on the multi-objective wolf pack algorithm.

The Longfeng Wetland of Daqing City in China was taken as the research object to determine a reasonable sewage reduction scheme and resolve the pollution of urban wetland ecosystems. First, the main pollutants, including dichromate oxidizability (COD), ammonia nitrogen (NH-N), total phosphorus (TP), and petroleum, were selected as indices. A two-dimensional hydrodynamic and water quality coupling model was established using MIKE 21. An optimal regulation method to improve the water quality of the wetland was then proposed following the numerical simulation method, and a multi-objective optimization model is established. The model establishes two objective functions based on wetland pollutant and water quality requirements. The model's constraints include hydrodynamic conditions and water quality conditions, and it considers the control point of the sewage concentration, sewage outfall processing capacity, depth of treatment, and changes in the water cycle. The wolf pack algorithm is introduced to resolve the multi-objective problem of sewage outfall optimization, and an optimal sewage scheme is obtained. According to the results of the scheme, some measures are proposed to manage the pollutants in urban wetland waters.