Estonia, Valkla

Valkla is an ancient village. In 1241 it was registered in written records that there were 40 “smoke” in the village. Today, the village population is around 480, incl. 145 Valkla Social Welfare House residents. Seventy percent of the population is of working age, 13% are under age 18 and 17% over age 65.

The area of Valkla is 1676 hectares. Agricultural areas account for about 62% and forests for about 37% of the total. Valkla creek flows through the village and ends up in the Gulf of Finland (Kolga Gulf). The creek is 12.5 km long and the catchment area is 46.5 km², most of which is located in the Valkla area. The village is sparsely populated with a population density of 0.3 persons per hectare.

Situation before technological changes

The pilot object is the sewage treatment system of two apartment buildings (49 inhabitants). The wastewater biological treatment system (EKE-B 21) constructed in the beginning of the 1970s mainly for organic matter removal is outdated. Thus, the households’ sewage is collected into concrete holding tank and gully-emptier trucks transport it to the nearest WWTP twice a week.

After construction of the new wastewater treatment facility, the treated effluent will be discharged into Valkla creek. Notably, in the village, groundwater is unprotected or weakly protected in most of locality. Moreover, Valkla creek is a salmonid waterbody and the mouth of the creek is a protected area.

Current state of the pilot

The renovation of the outdated wastewater treatment facilities was initiated by Kuusalu Municipality and realised by Kuusalu Soojus OÜ. TTÜ helped other partners by providing knowhow in how to design and construct an advanced biological wastewater treatment system (sequencing batch reactors (SBR), activated sludge process) in order to provide efficient organic load removal, decrease the amount of nutrients loaded into the environment, and bring the general quality of the effluent into compliance with national regulations.

Construction of new WWTP and renovation of local pipelines was conducted in November 2017 and adjustment of the SBR operation was completed in March 2018.

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