Wastewater treatment plant in Uppsala, Sweden

Wastewater treatment plant in Uppsala, Sweden. Photo: SEI.

About one-third of all sludge generated in Sweden is currently spread on farmland, which makes it the most common form of sewage sludge management in Sweden. The practice is also expanding, growing 36% from 2014–2016. Most of the rest is reused as landscaping soil or to cap old landfill sites.

In 2018, a Swedish government inquiry was set up to explore how to implement a ban on the decades-old practice of spreading sewage sludge on farmland and set new requirements for recycling the phosphorus found in sludge. The ban was portrayed as a means to both reduce the environmental and food safety risks of direct sludge application and accelerate the transition to a complete circular economy for phosphorus, a vital plant nutrient and finite mineral – both laudable goals.

When the inquiry reported its findings in January 2020, it recommended two alternatives: a complete ban on all agricultural and other reuse options or a limited ban on reuse, allowing sludge to be spread on farmland if it meets strict quality standards (but not landscaping or landfill capping).

Both options included new quantitative targets for recycling of phosphorus and would impose significant – though different – costs on Swedish municipalities, which are responsible for wastewater management.

“This brief uses the inquiry’s recommendations to look at the impact that national policy directives can have on speeding up the transition to a circular economy and their implications on the ground – including the potential risks for cities like Uppsala, which has invested heavily in reuse – of being a frontrunner in sustainability policy.”

Policy recommendations

The following policy recommendations are offered as a guide for discussions on coming national policy between national and local officials.

  • As most experts have stated in reaction to the inquiry report, the second option – the continued use of sludge on farmland, but with stricter quality standards – is preferable.
  • Protect upstream work such as that under REVAQ, whose value in reducing pollution at the source has been proved by Uppsala and other municipal operators.
  • Ensure municipalities have sufficient time to implement whatever new policy is chosen and as far as possible support efforts to build new markets for sludge and/or phosphorus reuse.
  • Remember that not all sludge is equal. Sewage sludge can have different attributes pertaining to composition and potential contamination, depending on the inputs and the treatment processes used by the treatment plant.
  • Broaden the focus beyond phosphorus. Notably, the organic matter in sludge is valuable for soil improvement, but is obviously lost during incineration. Policy recommendations should leave space for technology options that exploit the full range of societal value contained in sludge.

This brief is part of a series of three briefs describing real-world examples of policies or programmes intended to accelerate implementation of ecotechnologies that reduce nutrient losses, and encourage nutrient reuse in the three BONUS RETURN case study basins: Fyrisån (Sweden), Vantaanjoki (Finland) and Słupia (Poland).