Wastewater directly impacts individuals’ health; hence, this topic is always a flame to motivate scientists to research treatment solutions. In terms of economy and infrastructure, building wastewater treatment systems is a significant and prominent challenge and problem in developing countries. Therefore, to construct a foundation for determining wastewater treatment solutions and building their management systems, we have proposed a lightweight ontology for wastewater treatment (WT) management. In particular, we concentrate on the keys of Biological Methodologies because these approaches are suitable for the environment and topography of Vietnam, especially at low cost. Accordingly, we pay attention to implementing this modeling by analyzing and classifying the primary biological and geographical features to serve in searching WT companies. Moreover, we leverage description logic that underlies the web ontology language OWL2-EL for representation, reasoning, and querying WT ontology-based modeling.