RISCLE Wastewater Treatment Plant, Riscle, Occitanie, France

RISCLE is a wastewater treatment plant located in Riscle, a commune in the Gers department of Occitanie, southern France. The facility serves a population of approximately 2,100 residents and is situated near the Adour River basin, which flows through the region. As a municipal plant, it plays a key role in managing local wastewater for this small agglomeration. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 2,500 m³/day and a current discharge volume of 374.64 m³/day, the facility operates well below its capacity, indicating room for future growth or seasonal variations. Advanced treatment typically includes nutrient removal, reducing the environmental impact on receiving waters. Treated effluent from RISCLE is discharged into the local watershed, which ultimately drains into the Adour River and then into the Bay of Biscay (Atlantic Ocean). The plant's advanced treatment helps protect downstream aquatic ecosystems, including the Adour's diverse fish populations and migratory species. Its inland location reduces direct marine discharge risks, but the plant's performance is still critical for maintaining water quality in the region's rivers.

RISCLE's treated wastewater enters the local tributaries of the Adour River, which flows westward through the Gers and Landes departments before reaching the Bay of Biscay. The Adour basin supports diverse aquatic life, including Atlantic salmon and European eel, and is an important migratory corridor. The plant's advanced treatment helps minimize nutrient loading and protects downstream habitats from eutrophication.