Small-scale wastewater treatment systems: governance, efficiency, resources recovery, environment contamination risks and innovative solutions for processes optimization
pipe discharging wastewater into the environment plus logos

Project information

Project duration


Funded by

European Structural and Investment Funds - INTERREG

Funding amount

776 503 EUR

Project coordinator

University of Oulu

Contact information

Project leader

Contact person

Project description

Project goals

  • To examine the governing principles of wastewater treatment systems not connected to sewage networks in Finland, Sweden and Norway as a means to highlight practices, strategies and regulations with the best outcomes in relation to environmental protection as well as social-economical and sustainable development.
  • To increase the available knowledge and thus our capabilities to estimate the purification efficiency of small-scale wastewater treatment systems and the risks of environmental contamination from discharged pollutants (regulated and unregulated substances) in northern regions.
  • To test and develop innovative engineering solutions for improving the removal of target substances (N and selected micropollutants) in small-scale wastewater treatment systems as well as to evaluate environmentally feasible options for resources recovery from sanitation systems in Nordic regions.

Project Partners and Work Packages

  • University of Oulu (OU, Water, Energy and Environmental Engineering research unit, Project leader, Finland),
  • Luleå University of Technology (LTU, Department of Civil, Environmental and Natural Resources Engineering, Sweden) and
  • Finnish Environment Institute (SYKE, Laboratory Centre, Freshwater Centre and Centre for Sustainable Consumption and Production, Finland).


New Event!

The ON-SITE project is ending and the methodologies and findings of the research conducted during the project will be presented in an ONLINE seminar.

Date: 29/03/2022

Time: 13:00 to 15:30 (UTC +2:00)

Seminar program

You can register for the seminar using the link: https://link.webropol.com/s/onsiteSeminar

Past Events!

Finnish speakers joined the project partners and representatives of several stakeholder groups for a morning of experience sharing and discussions on the topic of sanitation systems outside the sewage network!

You can find the material for the seminar presentation (Finnish) in the links below

Viemäriverkoston ulkopuolisia jätevesijärjestelmiä koskevat säännökset ja strategiat: Kuinka olemme tässä? Ari Kangas Neuvotteleva virkamies Ympäristöministeriö

Viemäriverkoston ulkopuolisten jätevesijärjestelmien hallinta Suomessa: Sääntely verrattuna tilanteeseen kentällä Vuokko Laukka Suomen ympäristökeskus, SYKE

Viemäriverkoston ulkopuoliset jätevesijärjestelmät: Kuntien vastuut ja haasteet Lakimies Marko Nurmikolu, Kuntaliitto

Miten kunnassa pärjätään hajajätevesien kanssa? Merja Talvitie, Hulevesi-insinööri, kadut ja liikenne, Oulun kaupunki

Pienten jätevesijärjestelmien toiminta: Tilastollisen analyysin tuloksia laajan mittausaineiston perusteella Suomessa ja Ruotsissa Väitöskirjatutkija Juho Kinnunen, Oulun yliopisto

Ravinteet ja haitta-aineet viemäriverkon ulkopuolisista jätevesijärjestelmistä ja niiden mahdolliset ympäristövaikutukset: Case Vähäjärvi Väitöskirjatutkija Juho Kinnunen, Oulun yliopisto

Tehdasvalmisteisten jätevesien puhdistusjärjestelmien kehitys, käyttö ja tehokkuus arno Huhta (Product manager), Pipelife Finland Oy.

Governance of on-site sanitation


Governance of on-site sanitation in Finland, Sweden and Norway

The governing principles and practices of wastewater treatment systems not connected to sewage networks in Finland, Sweden, and Norway were investigated. The extensive information gathered via legislation and literature review, stakeholders interviews, and expert analysis was combined in a report published in the Finish Environment Institute report series in February 2022 which can be assessed online via the link.


The report is in English and has abstracts in Finnish, Swedish and Norwegian languages.

On-Site Units Efficiency and Impact

  • Existing on-site small-scale wastewater treatment systems in Northern Finland and Northern Sweden (e.g., households, small communities and tourist centers) are being monitored (9 sites in Sweden and 14 in Finland).
  • Sites have been selected in a cooperative effort of the proposal’s partner institutions, environmental authorities, local communities and units producers (suppliers).
  • Inflow (when possible) and outflow water samples from different units are taken regularly and analyzed for nutrient, organic matter, solids and pathogen content.
  • Factors affecting on-site units efficiency is investigated via extensive analysis on data available from different projects studying decentralized wastewater treatment in Finland and Sweden containing over 1300 analysis results of over 400 different individual sites sampled.


Sensitive locations are selected and the on-site wastewater treatment units and surrounding environment are monitored extensively to evaluate the environmental impacts. Selected units, soil, water (surface water and/or groundwater depending on the site) and sediment samples are taken to evaluate the environmental impact of discharged contaminants. Two sites have been studied, 1 in Sweden and 1 in Finland.

Study Sites

Vähäjärvi Lake, Kokkola, Finland.

Vähäjärvi is a shallow lake and the turnover time of water is relatively long making the accumulation of nutrients more probable. Based on aerial photographs, vegetation cover can reach around 30 % of the lake surface during late summer. This is hindering the recreational use of the lake severely together with the accumulation of sediments on the bottom of the lake. Several on-site wastewater treatment systems are in use around the lake shores. The area was selected as the study site for WP4 of the project where possible environmental impacts of discharges from on-site treatment systems are investigated.


Elisangela Heiderscheidt (UO, project manager)


Inga Herrmann (LTU)


Nilivaara Ritva (SYKE)