A Study of the Planning of Water Pollution Control for Second Songhua River in China

The paper takes the Second Songhua River as an object for research and selects Thomas's BOD-DO stable model as the initial structure on the basis of overall investigations and analyses on water pollution in every reach. In view of the characteristics of the river being located at the north, values k’₁, k’₂ and k’₃ in dry season of winter were determined and calculated, and a series analyses have been made. The self-purification ability of the river and the total elimination amount of the main pollutants BOD₅ were also calculated. In order to minimize the required cost, we distributed the cost to the main pollution sources, which are to be controlled. We firstly set a cost function of sewage treatment plant by series design and calculated the related cost parameters, then calculated two kinds of optimal distributing models of BOD₅ elimination, which were a mathematical model of extreme value of conditions and a matrix mathematical model. Now they have been applied to the practical pollution control plan for the Second Songhua River.