Economic feasibility assessments represent a key issue for selecting which wastewater treatment processes should be implemented. The few applications that exist focus on the positive economic value of
externalities, overlooking the existence of negative externalities. However, wastewater treatment plants
(WWTPs) consume a significant amount of energy, contributing to climate change. In this context, as a
pioneering approach, greenhouse gas emissions (GHG) have been incorporated as a negative externality
of wastewater treatment. Within this framework, this study aims to compare the economic feasibility of
five technologies, both intensive and extensive, for small communities. The results show that both the
investment and operation costs are higher for intensive than for extensive technologies. Moreover,
significant differences in the value of negative externalities were observed. This study demonstrates that
from an economic perspective, constructed wetland is the most suitable option for treating wastewater
in small agglomerations.
