Ejido Libertad Número Dos Wastewater Treatment Plant, Culiacán, Sinaloa

Ejido Libertad Número Dos is a municipal wastewater treatment plant located in the community of Ejido Libertad Número Dos (Píramo Viejo), within the municipality of Culiacán, Sinaloa, Mexico. The plant serves a small population of 821 residents, reflecting its role in a rural or peri-urban setting. As a secondary treatment facility, it provides biological treatment to reduce organic pollutants and suspended solids before discharge. The plant has a designed capacity of 86.40 cubic meters per day and currently treats an average of 77.76 cubic meters daily, operating below its full capacity. In Mexico, wastewater treatment plants of this scale are regulated under the National Water Law (Ley de Aguas Nacionales) and must comply with official standards (NOM-001-SEMARNAT-1996) that set maximum permissible limits for contaminants in treated wastewater. Secondary treatment is the minimum required for most municipal discharges to protect water quality. The treated effluent is discharged into local water bodies that ultimately drain into the Pacific Ocean via the Sinaloa River basin. The plant's operation helps reduce pollution loads in the region's waterways, supporting downstream ecosystems and agricultural water use. Its location more than 10 km from the coast reduces direct marine impact, but it still contributes to the overall health of the coastal watershed.

The plant discharges into the Sinaloa River basin, which flows into the Pacific Ocean near the Gulf of California. This region supports diverse aquatic life, including fish and migratory birds, and is important for local agriculture and fisheries. The secondary treatment process reduces organic matter and pathogens, helping to maintain water quality in downstream rivers and coastal areas.