Estonia, Kolgaküla

Kolgaküla (Kolco) is an ancient village, which was first mentioned in written records in 1290. The population of Kolgaküla is around 185, with 64% of working age, 21% under age 18 and 15% over age 65. The village is sparsely populated, the density being 0.1 persons per hectare. 

The village crosses Baltic Klint. The bare fields of the alvar are windy and poor, and the berm of the klint is partially covered with hazelnut trees in a mixed forest, surrounding mostly by pine and spruce forests. Forests account for about 65% and agricultural areas 33% of the total area of Kolgaküla. The river Valgejõgi borders the village on one side, on the other side lies a marshy and dense spruce forest as well as Lake Lohja and a flooded clay quarry.

Situation before technological changes

The pilot object is the separate sewage treatment system for two apartment houses (33 inhabitants in total). The existing wastewater treatment system (BIO-50 and 2 oxidation ponds) constructed at the end of the 1970s was mainly designed for organic matter removal.

The  wastewater biological treatment solution (BIO-50), is no longer working properly and currently not used. Thus, wastewater is directly discharged into the oxidation ponds (2500 m²) and discharged into Punsu creek.

After construction of the new sewage treatment facility, the treated effluent will be also discharged into Puntsu creek. It should be noted, that in Kolgaküla, groundwater is unprotected or weakly protected in most of the local municipality’s territory.

What happens in the pilot

Kuusalu Municipality initiated the renovation of outdated wastewater treatment facilities. Kuusalu Soojus OÜ will realise the construction and provide maintenance for the new WWTP. Tallinn University of Technology will help other partners by providing knowhow in how to design and construct advanced biological wastewater treatment system (sequencing batch reactor (SBR), activated sludge process) in order to efficiently remove the organic load, decrease the load of nutrients into the environment, and bring the general quality of the effluent into compliance with the national regulations.

Construction of new WWTP and renovation of local pipelines was conducted in February 2018 and adjustment of the SBR operation should be completed in April-May 2018.

TTÜ is responsible for monitoring the efficacy of new treatment system as well as the environmental status of Puntsu creek by conducting water analyses before and after the renovation.