TP 670 of Pyhasalmi - Advanced Wastewater Treatment in Pyhäsalmi, Finland

TP 670 of Pyhasalmi is a wastewater treatment plant located in Pyhäsalmi, within the municipality of Pyhäjärvi in the Pohjois-Pohjanmaa region of Finland. The plant serves a population of approximately 4,600, making it a small to medium-sized facility in the Finnish wastewater network. The plant employs advanced treatment processes, which go beyond the secondary treatment standard required by the EU Urban Waste Water Treatment Directive (91/271/EEC). For agglomerations of this size, Finnish regulations typically mandate nutrient removal to protect sensitive water bodies, and advanced treatment ensures high removal rates for organic matter, nitrogen, and phosphorus. The treated effluent is discharged into the local watershed, which ultimately drains into the Baltic Sea via the Pyhäjoki river system. The Baltic Sea is a brackish and ecologically sensitive sea with eutrophication challenges, making nutrient removal critical. The plant's advanced treatment helps reduce the nutrient load entering this vulnerable marine environment.

The plant discharges into the Pyhäjoki river basin, which flows into the Bothnian Bay of the Baltic Sea. The Baltic Sea is a semi-enclosed brackish sea highly susceptible to eutrophication from nutrient inputs. Advanced treatment at this plant helps mitigate phosphorus and nitrogen loads, supporting the ecological health of downstream aquatic habitats and the coastal zone.