Technical economic analysis of stabilization ponds

Employing stabilization pond systems to treat wastewater has the advantages of being economical of energy, easy to operate, and low in operation costs. However, stabilization pond systems have the problem of occupying large areas of land. Therefore, only after an overall technical economic analysis is made can an assessment be made of whether it is feasible to employ a stabilization pond systems to treat wastewater. During the period of the Seventh Five-year Plan of China, the “Study on the Technology of Stabilization Ponds” was set as one of the national scientific and technological key items. Seven experimental bases were established ranging from the north down to the south of China. With the great numbers of operational data obtained from both these bases and the existing stabilization pond systems, an analysis of the composition of the capital outlay in the stabilization pond system construction was made. The analysis shows that the land purchase cost accounts for approximately 60% of the capital outlay in construction and is the most important influencing factor. A comparison between the various costs of stabilization pond systems and those of conventional sewage treatment plant was made. Thereupon two new parameters were put forward: “equal capital land cost” and “upper limit of feasible land cost”. At the same time, a nationwide isogram of these two parameters was plotted. This isogram may be useful for preliminary design and planning purposes, and may be helpful to the users to assess comparatively easily whether its feasible to employ stabilization pond system.