The objective of the installation and operation of wastewater treatment systems is to assure an environmentally friendly effluent quality meeting the determined border values. The high costs for construction, maintenance and operation of conventional treatment systems exert economic (and social) pressure, even in developing countries. Therefore, all over the world engineers look for creative, cost-effective and environmentally sound ways to control water pollution. Wastewater technology has been improved substantially during the last few decades.

When selecting a wastewater system, initially many processes are theoretically competitive. To determine the most economical alternative a cost-effectiveness-analysis including investment costs and operation costs has to be conducted [Tsagirakis et al, 2003; Medina, 2005]. For example a simple treatment system with low investment costs may have high operational expenses and therefore will be the alternative with the highest total costs.

An evaluation done early during the design process has the advantage of providing an early warning if an alternative design is too costly relative to the available resources, saving the trouble of preparing final designs for those technologies that are outsides the bounds of affordability. The evaluation can be seen as an early screening of the options, which have passed the basic tests of technical and social feasibility.

This module will give detailed information about operation costs for wastewater treatment systems. The main components, which are affecting the extend of operation costs, are identified.