Sweco is exploring receipt and utilisation options for septic tank and cesspool sludge in Southwest Finland

The region of Southwest Finland is seeking to establish itself as an environmental pioneer and ensure the cleanliness of the water systems and the archipelago in the area.

Southwest Finland has decided to make the transition to the centralised transportation of wastewater sludge generated by housing in sparsely populated areas. The analyses prepared so far indicate that a substantial amount of sludge ends up outside official treatment locations each year. Untreated sludge that ends up in the environment is increasing the nutrient load in the Baltic Sea and nearby water systems significantly.

“The Southwest Finland Waste Management Committee has decided that, as of 1 January 2020, the septic tank and cesspool sludge generated in the operating area will be received by Lounais-Suomen Jätehuolto Oy according to the rate confirmed by the Committee. A decision has also been made regarding a phased transition to municipality-organised waste transportation between 2021 and 2026, in accordance with the Waste Act,” says Jyri Metsäranta, production manager at Lounais-Suomen Jätehuolto Oy, which is owned by the municipalities in the region.

This decision makes Southwest Finland one of the pioneers with regard to the management of sludge materials outside the sewer network. This furthers the municipalities’ own environmental goals and ensures that Southwest Finland is taking care of its special responsibility for the cleanliness of the water systems and archipelago in the area.

Sweco is preparing a survey on the arrangement of collection and treatment

Sweco is currently working on a survey that will specify the sludge volumes and explore the possibilities for organising transportation and treatment. Within the operating area formed by 17 municipalities, there are some 45,000 properties outside the centralised sewer network.

“Our intention is to explore the options for the receipt and utilisation of septic tank and cesspool sludge that are under the responsibility of the municipality. The aim is to build a comprehensive collection network and ensure that the sludge is utilised cost efficiently and in accordance with the principles of the circular economy. Appropriate sludge management is key in the efforts to reduce the nutrient load on the Baltic Sea,” Jyri Metsänranta says, in reference to the goals of the survey.

Antti Ryynänen, who is Sweco’s project manager for the analysis efforts, is excited about the tasks at hand.

“For us at Sweco, it’s important to be involved in the development of more sustainable societies. We’ve put together a multidisciplinary in-house project team here at Sweco, including geographic data specialists, experts in wastewater sludge collection and treatment processes, and professionals in the field of traffic and logistics,” Ryynänen explains.

“Significant amounts of sludge end up outside collection sites in Southwest Finland and other parts of Finland. Centralised transport arrangements will facilitate development and the utilisation of sludge in a way that promotes environmental protection and the circular economy,” Ryynänen adds.

Municipally organised transport by 2026

For Lounais-Suomen Jätehuolto Oy, the survey is an element in charting the overall situation and planning optimal contract areas, after which the competitive bidding for transport solutions will be planned. The invitation to tender for the first contract area will most likely be published in the summer of 2020.

Of the municipalities in the region, Kemiönsaari has been using municipally-organised sludge transport since 2013. Centralised sludge transport is intended to begin in all municipalities within the operating area in phases between 2021–2026.