French reed bed as a solution to minimize the operational and maintenance costs of wastewater treatment from a small settlement: An Italian example

Abstract

French Reed Bed (FRB) is a particular constructed wetland (CW) solution which receives raw wastewater. Data from the full-scale FRB wastewater treatment plant of Castelluccio di Norcia (center of Italy) were collected to show the FRB capability to minimize the operational and management (O & M) costs. The system was designed to treat wastewater variable from 200 person equivalent (PE) in off-season up to 1000 PE. Data from 2014 up to 2016 showed high removal efficiency in line with French experiences with FRBs. An interview was conducted with the Water Utility to estimate the operational and maintenance (O & M) costs faced by the WWTP, which allowed us to detail the O & M costs for energy consumption, water quality samples, and personnel for inspection. Other O & M expenditure items were estimated on the basis of parametric costs from the executive design. The FRB O & M costs in euro for 500-1000 PE (6-11 €; PE-1 year-1) resulted from 5 to 13 lower in comparison to those reported for classical activated sludge systems in an Italian context (45-90 · year-1). The low O & M costs are mainly due to the limited energy consumed and to the minimized costs of sludge management.