BIO 400 Wastewater Treatment Plant, Skrīveru pagasts, Aizkraukles novads, Latvia

BIO 400 is a wastewater treatment facility located in Skrīveru pagasts, within Aizkraukles novads, Latvia. The plant serves a population of 434 and operates with secondary treatment, which is appropriate for small agglomerations under the EU Urban Waste Water Treatment Directive (91/271/EEC). The plant has a designed capacity of 3,000 m³/day, with a current discharge volume of 74.93 m³/day, indicating significant spare capacity. As a secondary treatment plant, BIO 400 provides biological treatment to reduce organic matter and suspended solids. Under the EU UWWTD, secondary treatment is the minimum requirement for all inland agglomerations above 2,000 population equivalent, though smaller plants like this one may also be subject to national regulations. The plant's low discharge volume relative to its design capacity suggests it is well-sized for future growth or seasonal variations. The treated effluent from BIO 400 is discharged into the local watershed, which ultimately drains into the Daugava River basin. The Daugava River flows through Latvia and into the Baltic Sea, supporting diverse aquatic ecosystems. The plant's inland location, over 50 km from the coast, reduces direct marine impact, but its discharge contributes to the overall water quality in the Daugava basin.

BIO 400 discharges into the Daugava River basin, which flows through Latvia and into the Baltic Sea. The Daugava is a major river supporting diverse fish populations and migratory species. The Baltic Sea is sensitive to eutrophication, making nutrient management important for all discharges in the basin.