BELIN BELIET 2 Wastewater Treatment Plant, Belin-Béliet, Nouvelle-Aquitaine

BELIN BELIET 2 is a municipal wastewater treatment plant located in Belin-Béliet, a commune in the Gironde department of Nouvelle-Aquitaine, southwestern France. The plant serves a small population of 832 residents and has a designed capacity of 2,000 cubic meters per day, with an average discharge volume of 148.43 m³/day. As a secondary treatment facility, BELIN BELIET 2 operates under the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires secondary treatment for agglomerations with a population equivalent (PE) between 2,000 and 10,000. Although the plant's population served is below this threshold, the directive's framework ensures that discharges meet quality standards for biochemical oxygen demand and suspended solids. The plant's treated effluent is discharged into the local watershed, which ultimately drains into the Arcachon Bay via the Leyre River and its tributaries. The Arcachon Bay is a semi-enclosed marine ecosystem that supports extensive seagrass beds, shellfish farming, and migratory bird populations. The plant's secondary treatment helps protect this ecologically sensitive coastal environment from nutrient pollution and organic loading.

The treated effluent from BELIN BELIET 2 enters the local stream network, which flows into the Leyre River and then into the Arcachon Bay, a large coastal lagoon on the Atlantic coast of France. The bay is a vital nursery for fish and supports oyster and mussel aquaculture. Nutrient inputs from wastewater must be carefully managed to prevent eutrophication, which can harm seagrass meadows and disrupt the bay's ecological balance.