Horizoni heitveepuhasti - Closed Secondary Treatment Plant in Kehra linn, Estonia

Horizoni heitveepuhasti is a wastewater treatment plant located in Kehra linn, within Anija vald, Harju maakond, Estonia. The plant was designed to serve the local population and industrial areas, with a substantial capacity of 115,000 m³/day. It is situated inland, more than 10 km from the coast, and its operations were regulated under Estonian environmental law, which aligns with EU directives. The plant provided secondary treatment, a standard level for municipal wastewater in Estonia under the EU Urban Waste Water Treatment Directive (91/271/EEC). This directive requires secondary treatment for agglomerations of this scale, ensuring the reduction of organic matter and suspended solids. The plant's closure may reflect upgrades or consolidation of regional infrastructure. The treated effluent was discharged into local water bodies, likely contributing to the Soodla River or nearby streams. These waters flow into the Gulf of Finland via the Jägala River, supporting diverse aquatic ecosystems. The plant's operation helped protect downstream environments, including the Baltic Sea, from nutrient pollution.

The plant's discharge likely entered the Soodla River, a tributary of the Jägala River, which flows into the Gulf of Finland, part of the Baltic Sea. The Baltic Sea is a brackish, semi-enclosed sea sensitive to eutrophication from nutrient inputs. The secondary treatment at Horizoni heitveepuhasti would have reduced organic pollutants, but nutrient removal may have been limited, depending on specific permit conditions. The surrounding area includes forests and agricultural land, with the plant playing a role in maintaining local water quality.